Melatonin ameliorates Aβ42‐induced alteration of βAPP‐processing secretases via the melatonin receptor through the Pin1/GSK3β/NF‐κB pathway in SH‐SY5Y cells J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-08 Vorapin Chinchalongporn; Mayuri Shukla; Piyarat Govitrapong
Melatonin is involved in the physiological regulation of the β‐amyloid precursor protein (βAPP)‐cleaving secretases which are responsible for generation of the neurotoxic amyloid beta (Aβ) peptide, one of the hallmarks of Alzheimer's disease (AD) pathology. In this study, we aimed to determine the underlying mechanisms of this regulation under pathological conditions. We establish that melatonin prevents Aβ42‐induced downregulation of a disintegrin and metalloproteinase domain‐containing protein 10 (ADAM10) as well as upregulation of β‐site APP‐cleaving enzyme 1 (BACE1) and presenilin 1 (PS1) in SH‐SY5Y cell cultures. We also demonstrate that the intrinsic mechanisms of the observed effects occurred via regulation of nuclear factor kappa‐light‐chain‐enhancer of activated B cells (NF‐κB) and glycogen synthase kinase (GSK)‐3β as melatonin reversed Aβ42‐induced upregulation and nuclear translocation of NF‐κBp65 as well as activation of GSK3β via its receptor activation. Furthermore, specific blocking of the NF‐κB and GSK3β pathways partially abrogated the Aβ42‐induced reduction in the BACE1 and PS1 levels. In addition, GSK3β blockage affected α‐secretase cleavage and modulated nuclear translocation of NF‐κB. Importantly, our study for the first time shows that peptidyl‐prolyl cis‐trans isomerase NIMA‐interacting 1 (Pin1) is a crucial target of melatonin. The compromised levels and/or genetic variation of Pin1 are associated with age‐dependent tau and Aβ pathologies and neuronal degeneration. Interestingly, melatonin alleviated the Aβ42‐induced reduction of nuclear Pin1 levels and preserved the functional integrity of this isomerase. Our findings illustrate that melatonin attenuates Aβ42‐induced alterations of βAPP‐cleaving secretases possibly via the Pin1/GSK3β/NF‐κB pathway.
Melatonin‐mediated inhibition of Cav3.2 T‐type Ca2+ channels induces sensory neuronal hypoexcitability through the novel protein kinase C‐eta isoform J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-08 Yuan Zhang; Heyi Ji; Jiangong Wang; Yufang Sun; Zhiyuan Qian; Xinghong Jiang; Terrance P. Snutch; Yangang Sun; Jin Tao
Recent studies implicate melatonin in the antinociceptive activity of sensory neurons. However, the underlying mechanisms are still largely unknown. Here, we identify a critical role of melatonin in functionally regulating Cav3.2 T‐type Ca2+ channels (T‐type channel) in trigeminal ganglion (TG) neurons. Melatonin inhibited T‐type channels in small TG neurons via the melatonin receptor 2 (MT2 receptor) and a pertussis toxin‐sensitive G‐protein pathway. Immunoprecipitation analyses revealed that the intracellular subunit of the MT2 receptor coprecipitated with Gαo. Both shRNA‐mediated knockdown of Gαo and intracellular application of QEHA peptide abolished the inhibitory effects of melatonin. Protein kinase C (PKC) antagonists abolished the melatonin‐induced T‐type channel response, whereas inhibition of conventional PKC isoforms elicited no effect. Furthermore, application of melatonin increased membrane abundance of PKC‐eta (PKCη) while antagonism of PKCη or shRNA targeting PKCη prevented the melatonin‐mediated effects. In a heterologous expression system, activation of MT2 receptor strongly inhibited Cav3.2 T‐type channel currents but had no effect on Cav3.1 and Cav3.3 current amplitudes. The selective Cav3.2 response was PKCη dependent and was accompanied by a negative shift in the steady‐state inactivation curve. Furthermore, melatonin decreased the action potential firing rate of small TG neurons and attenuated the mechanical hypersensitivity in a mouse model of complete Freund's adjuvant‐induced inflammatory pain. These actions were inhibited by T‐type channel blockade. Together, our results demonstrated that melatonin inhibits Cav3.2 T‐type channel activity through the MT2 receptor coupled to novel Gβγ‐mediated PKCη signaling, subsequently decreasing the membrane excitability of TG neurons and pain hypersensitivity in mice.
A unified model of melatonin, 6‐sulfatoxymelatonin, and sleep dynamics J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-08 Romesh G. Abeysuriya; Steven W. Lockley; Peter A. Robinson; Svetlana Postnova
A biophysical model of the key aspects of melatonin synthesis and excretion has been developed, which is able to predict experimental dynamics of melatonin in plasma and saliva, and of its urinary metabolite 6‐sulfatoxymelatonin (aMT6s). This new model is coupled to an established model of arousal dynamics, which predicts sleep and circadian dynamics based on light exposure and times of wakefulness. The combined model thus predicts melatonin levels over the sleep‐wake/dark‐light cycle and enables prediction of melatonin‐based circadian phase markers, such as dim light melatonin onset (DLMO) and aMT6s acrophase under conditions of normal sleep and circadian misalignment. The model is calibrated and tested against group average data from 10 published experimental studies and is found to reproduce quantitatively the key dynamics of melatonin and aMT6s, including the timing of release and amplitude, as well as response to controlled lighting and shift work.
Melatonin attenuated retinal neovascularization and neuroglial dysfunction by inhibition of HIF‐1α‐VEGF pathway in oxygen‐induced retinopathy mice J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-08 Yue Xu; Xi Lu; Yaguang Hu; Boyu Yang; Ching‐Kit Tsui; Shanshan Yu; Lin Lu; Xiaoling Liang
Retinopathy of prematurity (ROP) is a retinopathy characterized by retinal neovascularization (RNV) occurring in preterm infants treated with high concentrations of oxygen and may lead to blindness in severe cases. Currently, anti‐VEGF therapy is a major treatment for ROP, but it is costly and may cause serious complications. The previous study has demonstrated that melatonin exerted neuroprotective effect against retinal ganglion cell death induced by hypoxia in neonatal rats. However, whether melatonin is anti‐angiogenic and neuroglial protective in the progression of ROP remains unknown. Thus, this study was to investigate the effect of melatonin on RNV and neuroglia in the retina of oxygen‐induced retinopathy (OIR) mice. The results showed a reduction in retinal vascular leakage in OIR mice after melatonin treatment. Besides, the size of retinal neovascular and avascular areas, the number of preretinal neovascular cell nuclei, and the number of proliferative vascular endothelial cells within the neovascular area were significantly decreased in mice treated with melatonin. After oxygen‐induced injury, the density of astrocytes was decreased, accompanied by morphologic and functional changes of astrocytes. Besides, retinal microglia were also activated. Meanwhile, the levels of inflammatory factors were elevated. However, these pathologic processes were all hindered by melatonin treatment. Furthermore, HIF‐1α‐VEGF pathway was activated in the retina of OIR mice, yet was suppressed in melatonin‐treated OIR mice retinas. In conclusion, melatonin prevented pathologic neovascularization, protected neuroglial cells, and exerts anti‐inflammation effect via inhibition of HIF‐1α‐VEGF pathway in OIR retinas, suggesting that melatonin could be a promising therapeutic agent for ROP.
Increase in motility and invasiveness of MCF7 cancer cells induced by nicotine is abolished by melatonin through inhibition of ERK phosphorylation J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-08 Sara Proietti; Angela Catizone; Maria Grazia Masiello; Simona Dinicola; Gianmarco Fabrizi; Mirko Minini; Giulia Ricci; Roberto Verna; Russel J. Reiter; Alessandra Cucina; Mariano Bizzarri
Through activation of the ERK pathway, nicotine, in both normal MCF‐10A and low‐malignant breast cancer cells (MCF7), promotes increased motility and invasiveness. Melatonin antagonizes both these effects by inhibiting almost completely ERK phosphorylation. As melatonin has no effect on nonstimulated cells, it is likely that melatonin can counteract ERK activation only downstream of nicotine‐induced activation. This finding suggests that melatonin hampers ERK phosphorylation presumably by targeting a still unknown intermediate factor that connects nicotine stimulation to ERK phosphorylation. Furthermore, downstream of ERK activation, melatonin significantly reduces fascin and calpain activation while restoring normal vinculin levels. Melatonin also counteracts nicotine effects by reshaping the overall cytoskeleton architecture and abolishing invasive membrane protrusion. In addition, melatonin decreases nicotine‐dependent ROCK1/ROCK2 activation, thus further inhibiting cell contractility and motility. Melatonin actions are most likely attributable to ERK inhibition, although melatonin could display other ERK‐independent effects, namely through a direct modulation of additional molecular and structural factors, including coronin, cofilin, and cytoskeleton components.
Melatonin increases brown adipose tissue mass and function in Zücker diabetic fatty rats: implications for obesity control J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-06 Gumersindo Fernández Vázquez; Russel J. Reiter; Ahmad Agil
Melatonin limits obesity in rodents without affecting food intake and activity, suggesting a thermogenic effect. Previously we demonstrated that melatonin browns subcutaneous fat in Zücker diabetic fatty (ZDF) rats. Other works pointed to melatonin as a signal that increases brown adipose tissue (BAT) mass and function in rodents. However, direct proof of thermogenic properties (uncoupled mitochondria) of the newly recruited BAT in response to melatonin is still lacking. Therefore, in the present work we investigated if melatonin recruits thermogenic BAT in ZDF rats. Zücker lean (ZL) and ZDF animals were subdivided into two groups, control (C) and treated with oral melatonin (M) for 6 weeks. Mitochondrial mass, activity of citrate synthase (CS) and respiratory chain complexes I and IV were lower in C‐ZDF than in C‐ZL animals (P < 0.001). Melatonin treatment increased BAT weight in ZDF rats (P < 0.001). Also, it rose mitochondrial mass (P < 0.01) and activities of CS and complexes I and IV (P < 0.001) in both, ZDF and ZL rats. Uncoupling protein 1 (UCP1) mRNA and protein were 50% lower in BAT from obese rats. Also, guanosine diphosphate (GDP) binding was lower in ZDF than in lean rats (P< 0.01). Melatonin treatment of obese rats restored the expression of UCP1 and GDP binding to levels of lean rats, and sensitized the thermogenic response to cold exposure. These data demonstrated that melatonin recruits thermogenic BAT in ZDF rats. This may contribute to melatonin′s control of body weight and its metabolic benefits.
Melatonin attenuates smoking‐induced hyperglycemia via preserving insulin secretion and hepatic glycogen synthesis in rats J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-13 Tianjia Li; Leng Ni; Zhewei Zhao; Xinnong Liu; Zhichao Lai; Xiao Di; Zhibo Xie; Xitao Song; Xuebin Wang; Rui Zhang; Changwei Liu
Epidemiology survey indicated that cigarette smoking is a risk factor of diabetes. However, the precise mechanisms remain to be clarified. In the current study, we found that smoking caused metabolic malfunctions on pancreas and liver in experimental animal model. These were indicated by hyperglycemia, increased serum hemoglobin A1c level and decreased insulin secretion, inhibition of liver glycogen synthase (LGS) and hepatic glycogen synthesis. Mechanistic studies revealed that all these alterations were caused by the inflammatory reaction and reactive oxygen species (ROS) induced by the smoking. Melatonin treatment significantly preserved the functions of both pancreas and liver by reducing β cells apoptosis, CD68‐cell infiltration, ROS production and caspase‐3 expression. The siRNA‐knockdown model identified that the protective effects of melatonin were mediated by melatonin receptor‐2 (MT2). The current study uncovered potentially underling mechanisms related to the association between smoking and diabetes. In addition, it is, for first time, to report that melatonin effectively protects against smoking induced glucose metabolic alterations and the signal transduction pathway of melatonin is mainly mediated by its MT2 receptor. These observations provide solid evidence for clinically use of melatonin to reduce smoking related diabetes and the therapeutic regimens are absent currently.
Mitochondrial cytochrome P450 (CYP) 1B1 is responsible for melatonin‐induced apoptosis in neural cancer cells J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-17 Zhenlong Yu; Xiangge Tian; Yuling Peng; Zheng Sun; Chao Wang; Ning Tang; Bin Li; Yuqing Jian; Wei Wang; Xiaokui Huo; Xiaochi Ma
Melatonin is an endogenous indoleamine with a wide range of biological functions in the various organisms from bacteria to mammals. Evidence indicates that melatonin facilitates apoptosis in cancer cells and enhances the anti‐tumor activity of chemotherapy in animals and clinical studies. However, the melatonin metabolism and the key metabolic targets in cancer cells still remain unknown. In this study, U118 and SH‐SY5Y tumor cell lines were used to investigate the metabolic pathways of melatonin in cancer cells. Interestingly, the inhibitory effect of melatonin on proliferation in SH‐SY5Y cells is more potent than that in U118 cells. In contrast, this inhibitory effect on the normal cells is absent. The antitumor effects of melatonin are positively associated with its metabolite N‐acetylserotonin (NAS). Unexpectedly, CYP1B1 is, for first time, identified to localize in the mitochondria of tumor cells, and it metabolizes melatonin to form NAS in situ, which subsequently triggers mitochondria‐dependent apoptosis in cancer cells. In normal cells, NAS does not induce apoptosis. A remarkable individual variation on CYP1B1expression was also detected in human tumor tissue. These findings provide the novel mechanisms regarding the anti‐tumor effects of melatonin in the level of mitochondria. Thus, we hypothesize that CYP1B1 overexpression in mitochondria would significantly enhance the anti‐tumor effects of melatonin. Mitochondrial CYP1B1 can potentially serve as a specific target to modify the therapeutic and biological effects of melatonin on cancer patients.
Melatonin protects against defects induced by deoxynivalenol during mouse oocyte maturation J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-17 Mei Lan; Jun Han; Meng‐Hao Pan; Xiang Wan; Zhen‐Nan Pan; Shao‐Chen Sun
Deoxynivalenol (DON) is one of the most prevalent Fusarium mycotoxins in feedstuff and food. DON causes detrimental effects on human and animal reproductive systems by inducing oxidative stress and apoptosis. While melatonin is a multifunctional endogenous hormone which plays crucial roles in the development of animal germ cells and embryos as a robust deoxidizer. In present study, we explored the effects of melatonin on the DON‐exposure mouse oocytes. Our in vitro and in vivo results showed that DON adversely affected mouse oocyte maturation and early embryo cleavage, while melatonin administration ameliorated the toxic effects of DON. DON exposure disrupted the meiotic spindle formation and kinetochore‐microtubule attachment, which induced aneuploidy in oocytes. This might be through DON effects on the acetylated‐tubulin level. Moreover, we found that DON exposure caused the alteration of DNA and histone methylation level, which might affect early embryo cleavage. The toxic effects of DON on oocytes might be through its induction of oxidative stress‐mediated early apoptosis. While the treatment with melatonin significantly ameliorated these phenotypes in DON‐exposed mouse oocytes. Collectively, our results indicated the protection effects of melatonin against defects induced by DON during mouse oocyte meiotic maturation.
Distribution and density of melatonin receptors in human main pancreatic islet cell types J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-21 Juliane Zibolka; Ivonne Bazwinsky‐Wutschke; Eckhard Mühlbauer; Elmar Peschke
Recent investigations of our group established that melatonin modulates hormone secretion of pancreatic islets via melatonin receptor types MT1 and MT2. Expression of MT1 and MT2 has been shown in mouse, rat and human pancreatic islets as well as in the β‐, α‐ and δ‐cell lines INS‐1, αTC1.9 and QGP‐1. In view of these earlier investigations, the present study was performed to analyze in detail the distribution and density of melatonin receptors on the main islet cell types in human pancreatic tissue obtained from non‐diabetic and type 2 diabetic patients. Immunohistochemical analysis established the presence of MT1 and MT2 in β‐, α‐ and δ‐cells, but notably, with differences in receptor density. In general, the lowest MT1 and MT2 receptor density was measured in α‐cells compared to the two other cell types. In type 2 diabetic islets, MT1 and MT2 receptor density was increased in δ‐cells compared to normoglycemic controls. In human islets in batch culture of a non‐diabetic donor an increase of somatostatin secretion was observed under melatonin treatment while in islets of a type 2 diabetic donor an inhibitory influence could be observed, especially in the presence of 5.5 mM glucose. These data suggest: i) cell‐type specific density of MT1 and MT2 receptors in human pancreatic islets, which should be considered in context of the hormone secretion of islets, ii) the influence of diabetes on density of MT1 and MT2 as well as iii) the differential impact of melatonin on somatostatin secretion of non‐diabetic and type 2 diabetic islets.
Systemic and transdermal melatonin administration prevents neuropathology in response to perinatal asphyxia in newborn lambs J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-21 James D S Aridas; Tamara Yawno; Amy E Sutherland; Ilias Nitsos; Michael Ditchfield; Flora Y Wong; Rod W Hunt; Michael C Fahey; Atul Malhotra; Euan M Wallace; Graham Jenkin; Suzanne L Miller
Perinatal asphyxia remains a principal cause of infant mortality and long term neurological morbidity, particularly in low resource countries. No neuroprotective interventions are currently available. Melatonin (MLT), a potent antioxidant, anti‐inflammatory, and anti‐apoptotic agent offers promise as an intravenous (IV) or transdermal therapy to protect the brain. We aimed to determine the effect of melatonin (IV or transdermal patch) on neuropathology in a lamb model of perinatal asphyxia. Asphyxia was induced in newborn lambs via umbilical cord occlusion at birth. Animals were randomly allocated to melatonin commencing 30 minutes after birth (60 mg in 24h; IV or transdermal patch). Brain magnetic resonance spectroscopy (MRS) was undertaken at 12 and 72h. Animals (control n=9; control+MLT n=6; asphyxia n=16; asphyxia+MLT [IV n=14; patch n=4]) were euthanized at 72h and CSF and brains collected for analysis. Asphyxia resulted in severe acidosis (pH 6.9±0.0; lactate 9±2 mmol/L) and altered determinants of encephalopathy. MRS lactate:N‐acetyl aspartate ratio was 2.5‐fold higher in asphyxia lambs compared with controls at 12h, and three‐fold higher at 72h (p<0.05). Melatonin prevented this rise (3.5‐fold reduced vs asphyxia; p=0.02). Asphyxia significantly increased brain white and gray matter apoptotic cell death (activated caspase‐3), lipid peroxidation (4HNE), and neuroinflammation (IBA‐1). These changes were significantly mitigated by both IV or patch melatonin. Systemic or transdermal neonatal melatonin administration, significantly reduces the neuropathology and encephalopathy signs associated with perinatal asphyxia. A simple melatonin patch, administered soon after birth, may improve outcome in infants affected by asphyxia, especially in low resource settings.
Melatonin activate FIS1, DYN1 and DYN2 Plasmodium falciparum related‐genes for mitochondria fission: mitoemerald‐GFP as a tool to visualize mitochondria structure J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-26 Pedro Scarpelli; Giulliana Tessarin Almeida; Kênia Lopes Viçoso; Wania Rezende Lima; Lucas Borges Pereira; Kamila Anna Meissner; Carsten Wrenger; Anna Rafaello; Rosario Rizzuto; Tullio Pozzan; Celia R. S. Garcia
Malaria causes millions of deaths worldwide and is considered a huge burden to underdeveloped countries. The number of cases with resistance to all antimalarials is continuously increasing, making the identification of novel drugs a very urgent necessity. A potentially very interesting target for novel therapeutic intervention is the parasite mitochondrion. In this work we studied in P. falciparum three genes coding for proteins homologues of the mammalian FIS1 (Mitochondrial Fission Protein 1) and DRP1 (Dynamin Related Protein 1) involved in mitochondrial fission. We studied the expression of P. falciparum genes that show ample sequence and structural homologies with the mammalian counterparts, namely FIS1, DYN1 and DYN2. The encoded proteins are characterized by a distinct pattern of expression throughout the erythrocytic cycle of Plasmodium falciparum and their mRNAs are modulated by treating the parasite with the host hormone melatonin. We have previously reported that the knock out of the Plasmodium gene that codes for protein kinase 7 is essential for melatonin sensing. We here show that PfPk7 knockout results in major alterations of mitochondrial fission genes expression when compared to wild type parasites, and no change in fission protein expression upon treatment with the host hormone. Finally we have compared the morphological characteristics(using MitoTracker Red CMX Ros. and oxygen consumption properties of P. falciparum mitochondria in wild type parasites and PfPk7 Knockout strains. A novel GFP construct targeted to the mitochondrial matrix to wild type parasites was also developed to visualize Plasmodium falciparum mitochondria. We here show that, the functional characteristics of P. falciparum are profoundly altered in cells lacking protein kinase 7, suggesting that this enzyme plays a major role in the control of mitochondrial morphogenesis and maturation during the intra erythrocyte cell cycle progression.
LIM homeobox transcription factor Isl1 is required for melatonin synthesis in the pig pineal gland J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-26 Jinglin Zhang; Jingtao Qiu; Yewen Zhou; Yue Wang; Hongjiao Li; Taojie Zhang; Ying Jiang; Kemian Gou; Sheng Cui
Melatonin is a key hormone that regulates circadian rhythms, metabolism and reproduction. However, the mechanisms of melatonin synthesis and secretion have not been fully defined. The purpose of this study was to investigate the functions of the LIM homeobox transcription factor Isl1 in regulating melatonin synthesis and secretion in porcine pineal gland. We found that Isl1 is highly expressed in the melatonin producing cells in the porcine pineal gland. Further functional studies demonstrate that Isl1 knockdown in cultured primary porcine pinealocytes results in the decline of melatonin and arylalkylamine N‐acetyltransferase (Aanat) mRNA levels by 29.2% and 72.2% respectively, whereas Isl1 overexpression raised by 1.3‐fold and 2.7‐fold. In addition, the enhancing effect of norepinephrine (NE) on melatonin synthesis was abolished by Isl1 knockdown. The in vivo intracerebroventricular NE injections upregulate Isl1 mRNA and protein levels by about 3‐fold and 4.5‐fold in the porcine pineal gland. We then examined the changes of Isl1 expression in the pineal gland and global melatonin levels throughout the day. The results show that Isl1 protein level at 24:00 is 2.5‐fold higher than that at 12:00, which is parallel to melatonin levels. We further found that Isl1 increases the activity of Aanat promoter, and the effect of NE on Isl1 expression was blocked by an ERK inhibitor. Collectively, the results presented here demonstrate that Isl1 positively modulates melatonin synthesis by targeting Aanat, via the ERK signaling pathway of NE. These suggest that Isl1 plays important roles in maintaining the daily circadian rhythm.
Role of MTNR1A and PITX1 coexpression in protecting tubular epithelial cells in membranous nephropathy J. Pineal. Res. (IF 10.391) Pub Date : 2018-02-26 Yen‐Sung Huang; Kuo‐Cheng Lu; Tai‐Kuang Chao; Jin‐Shuen Chen; Ann Chen; Cheng‐Yi Guo; Hsin‐Yi Hsieh; Hsiu‐Ming Shih; Huey‐Kang Sytwu; Chia‐Chao Wu
Membranous nephropathy (MN), a type of glomerular nephritis, is one of the most common causes of nephrotic syndrome in adults. Although it is known that melatonin plays a protective role in MN, the role of melatonin receptors in the pathophysiology of MN is unclear. Using an experimental MN model and clinical MN specimens, we studied melatonin receptor expression and found that melatonin receptor 1A (MTNR1A) expression was significantly downregulated in renal tubular epithelial cells. Molecular studies showed that the transcription factor pituitary homeobox‐1 (PITX1) promoted MTNR1A expression via direct binding to its promoter. Treatment of a human tubular cell line with albumin to induce injury resulted in the stable reduction of MTNR1A and PITX1 expression. PITX1 levels were significantly downregulated in tubular epithelial cells from mice MN kidneys and MN renal specimens. Knockdown of MTNR1A, PITX1, or cyclic adenosine monophosphate‐responsive element‐binding protein (CREB) decreased E‐cadherin (CDH1) expression, but upregulated Per2 and α‐smooth muscle actin (αSMA) expression. Blockade of the MTNR1A receptor with luzindole in MN mice further impaired renal function; this was accompanied by CDH1 downregulation and Per2 and αSMA upregulation. Together, our results suggest that in injured tissue, decreased PITX1 expression at the MTNR1A promoter regions leads to decreased levels of MTNR1A in renal tubular epithelial cells, which increases the future risk of MN.
Melatonin‐mediated miR‐526b‐3p and miR‐590‐5p upregulation promotes chondrogenic differentiation of human mesenchymal stem cells J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-01 Zizhao Wu; Xianjian Qiu; Bo Gao; Chengjie Lian; Yan Peng; Anjing Liang; Caixia Xu; Wenjie Gao; Liangming Zhang; Peiqiang Su; Limin Rong; Dongsheng Huang
Bone marrow‐derived mesenchymal stem cells (BMSCs), with inherent chondrogenic differentiation potential, appear to be ideally suited for therapeutic use in cartilage regeneration. Accumulating evidence has demonstrated that melatonin can promote chondrogenic differentiation in human BMSCs. However, little is known about the mechanism. MicroRNAs (miRNAs) have been shown to regulate the differentiation of BMSCs, but their roles in melatonin‐promoted chondrogenic differentiation have not been characterized. Here, we demonstrate that melatonin promoted chondrogenic differentiation of human BMSCs via upregulation of miR‐526b‐3p and miR‐590‐5p. Mechanistically, the elevated miR‐526b‐3p and miR‐590‐5p enhanced SMAD1 phosphorylation by targeting SMAD7. Additionally, administration of miR‐526b‐3p mimics or miR‐590‐5p mimics successfully promoted the chondrogenic differentiation of human BMSCs. Collectively, our study suggests that modification of BMSCs using melatonin or miRNA transduction could be an effective therapy for cartilage damage and degeneration.
Exogenous melatonin protects small‐for‐size liver grafts by promoting monocyte infiltration and releases interleukin‐6 J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-05 Zhuolun Song; Bostjan Humar; Anurag Gupta; Eleonora Maurizio; Nathalie Borgeaud; Rolf Graf; Pierre‐Alain Clavien; Yinghua Tian
Defective regeneration of small‐for‐size (SFS) liver remnants and partial grafts remains a key limiting factor in the application of liver surgery and transplantation. Exogenous melatonin (MLT) has protective effects on hepatic ischemia reperfusion injury (IRI), but its influence on graft regeneration is unknown. The aim of the study is to investigate the role of MLT in IRI and graft regeneration in settings of partial liver transplantation. We established three mouse models to study hepatic IRI and regeneration associated with partial liver transplantation: (I) IR+PH group: 60 min liver ischemia (IR) plus 2/3 hepatectomy (PH); (II) IR+exPH group: 60 min liver IR plus extended hepatectomy (exPH) associated with the SFS syndrome; (III) SFS‐LT group: Arterialized 30% SFS liver transplant. Each group was divided into MLT or vehicle‐treated subgroups. Hepatic injury, inflammatory signatures, liver regeneration, and animal survival rates were assessed. MLT reduced liver injury, enhanced liver regeneration, and promoted interleukin (IL) 6, IL10, and tumor necrosis factor‐α release by infiltrating, inflammatory Ly6C+ F4/80+ monocytes in the IR+PH group. MLT‐induced IL6 significantly improved hepatic microcirculation and survival in the IR+exPH model. In the SFS‐LT group, MLT promoted graft regeneration and increased recipient survival along with increased IL6/GP130‐STAT3 signaling. In IL6‐/‐ mice, MLT failed to promote liver recovery, which could be restored through recombinant IL6. In the IR+exPH and SFS‐LT groups, inhibition of the IL6 co‐receptor GP130 through SC144 abolished the beneficial effects of MLT. MLT ameliorates SFS liver graft IRI and restores regeneration through monocyte‐released IL6 and downstream IL6/GP130‐STAT3 signaling.
Melatonin biosynthesis enzymes recruit WRKY transcription factors to regulate melatonin accumulation and transcriptional activity on W‐box in cassava J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-12 Yunxie Wei; Guoyin Liu; Yanli Chang; Daozhe Lin; Russel J. Reiter; Chaozu He; Haitao Shi
Melatonin is widely involved in growth, development and stress responses in plants. Although the melatonin synthesis enzymes have been identified in various plants, their interacting proteins remain unknown. Herein, overexpression of tryptophan decarboxylase 2 (MeTDC2)‐interacting proteins, N‐acetylserotonin O‐methyltransferase 2 (MeASMT2) interacting proteins, and N‐acetylserotonin O‐methyltransferase 3 (MeASMT3) in cassava leaf protoplasts resulted in more melatonin than when other enzymes were overexpressed. Through yeast two‐hybrid, 14 MeTDC2‐interacting proteins, 24 MeASMT2 interacting proteins, and 9 MeASMT3‐interacting proteins were identified. Notably, we highlighted MeWRKY20 and MeWRKY75 as common interacting proteins of the three enzymes, as evidenced by yeast two‐hybrid, and in vivo bimolecular fluorescence complementation (BiFC). Moreover, co‐overexpression of MeTDC2/MeASMT2/3 with MeWRKY20/75 in cassava leaf protoplasts did not only activated the transcriptional activities of MeWRKY20 and MeWRKY75 on W‐box, but also induced the effects of MeTDC2, MeASMT2/3 on endogenous melatonin levels. Taken together, three melatonin synthesis enzymes (MeTDC2, MeASMT2/3) interact with MeWRKY20/75 to form a protein complex in cassava. This information significantly extends the knowledge of the complex modulation of plant melatonin signaling.
The environmental neurotoxin β‐N‐methylamino‐L‐alanine (BMAA) inhibits melatonin synthesis in primary pinealocytes and a rat model J. Pineal. Res. (IF 10.391) Pub Date : 2018-03-12 Paula Pierozan; Marie Andersson; Ingvar Brandt; Oskar Karlsson
The environmental neurotoxin β‐N‐methylamino‐L‐alanine (BMAA) is a glutamate receptor agonist that can induce oxidative stress and has been implicated as a possible risk factor for neurodegenerative disease. Detection of BMAA in mussels, crustaceans and fish, illustrates that the sources of human exposure to this toxin are more abundant than previously anticipated. The aim of this study was to determine uptake of BMAA in the pineal gland and subsequent effects on melatonin production in primary pinealocyte cultures and a rat model. Autoradiographic imaging of ten‐day‐old male rats revealed a high and selective uptake in the pineal gland at 30 min to 24 h after 14C‐L‐BMAA administration (0.68 mg/kg). Primary pinealocyte cultures exposed to 0.05‐3 mM BMAA showed a 57‐93% decrease in melatonin synthesis in vitro. Both the metabotropic glutamate receptor 3 (mGluR3) antagonist Ly341495 and the protein kinase C (PKC) activator phorbol‐12‐myristate‐13‐acetate, prevented the decrease in melatonin secretion, suggesting that BMAA inhibits melatonin synthesis by mGluR3 activation and PKC inhibition. Serum analysis revealed a 45% decrease in melatonin concentration in neonatal rats assessed two weeks after BMAA administration (460 mg/kg) and confirmed an inhibition of melatonin synthesis in vivo. Given that melatonin is a most important neuroprotective molecule in the brain, the etiology of BMAA‐induced neurodegeneration may include mechanisms beyond direct excitotoxicity and oxidative stress.
Melatonin and serotonin: Mediators in the symphony of plant morphogenesis J. Pineal. Res. (IF 10.391) Pub Date : 2018-01-11 Lauren A. E. Erland, Mukund R. Shukla, Amritpal S. Singh, Susan J. Murch, Praveen K. Saxena
Abstract Melatonin and serotonin are important signaling and stress mitigating molecules that play important roles across growth and development in plants. Despite many well-documented responses, a systematic investigation of the entire metabolic pathway (tryptophan, tryptamine, and N-acetylserotonin) does not exist, leaving many open questions. The objective of this study was to determine the responses of Hypericum perforatum (L.) to melatonin, serotonin, and their metabolic precursors. Two well-characterized germplasm lines (#4 and 112) created by mutation and a haploid breeding program were compared to wild type to identify specific responses. Germplasm line 4 has lower regenerative and photosynthetic capacity than either wild type or line 112, and there are documented significant differences in the chemistry and physiology of lines 4 and 112. Supplementation of the culture media with tryptophan, tryptamine, N-acetylserotonin, serotonin, or melatonin partially reversed the regenerative recalcitrance and growth impairment of the germplasm lines. Quantification of phytohormones revealed crosstalk between the indoleamines and related phytohormones including cytokinin, salicylic acid, and abscisic acid. We hypothesize that melatonin and serotonin function in coordination with their metabolites in a cascade of phytochemical responses including multiple pathways and phytohormone networks to direct morphogenesis and protect photosynthesis in H. perforatum.
Inhibiting MT2-TFE3-dependent autophagy enhances melatonin-induced apoptosis in tongue squamous cell carcinoma J. Pineal. Res. (IF 10.391) Pub Date : 2018-01-11 Tengfei Fan, Huifeng Pi, Min Li, Zhenhu Ren, Zhijing He, Feiya Zhu, Li Tian, Manyu Tu, Jia Xie, Mengyu Liu, Yuming Li, Miduo Tan, Gaoming Li, Weijia Qing, Russel J. Reiter, Zhengping Yu, Hanjiang Wu, Zhou Zhou
Abstract Autophagy modulation is a potential therapeutic strategy for tongue squamous cell carcinoma (TSCC). Melatonin possesses significant anticarcinogenic activity. However, whether melatonin induces autophagy and its roles in cell death in TSCC are unclear. Herein, we show that melatonin induced significant apoptosis in the TSCC cell line Cal27. Apart from the induction of apoptosis, we demonstrated that melatonin-induced autophagic flux in Cal27 cells as evidenced by the formation of GFP-LC3 puncta, and the upregulation of LC3-II and downregulation of SQSTM1/P62. Moreover, pharmacological or genetic blockage of autophagy enhanced melatonin-induced apoptosis, indicating a cytoprotective role of autophagy in melatonin-treated Cal27 cells. Mechanistically, melatonin induced TFE3(Ser321) dephosphorylation, subsequently activated TFE3 nuclear translocation, and increased TFE3 reporter activity, which contributed to the expression of autophagy-related genes and lysosomal biogenesis. Luzindole, a melatonin membrane receptor blocker, or MT2-siRNA partially blocked the ability of melatonin to promote mTORC1/TFE3 signaling. Furthermore, we verified in a xenograft mouse model that melatonin with hydroxychloroquine or TFE3-siRNA exerted a synergistic antitumor effect by inhibiting autophagy. Importantly, TFE3 expression positively correlated with TSCC development and poor prognosis in patients. Collectively, we demonstrated that the melatonin-induced increase in TFE3-dependent autophagy is mediated through the melatonin membrane receptor in TSCC. These data also suggest that blocking melatonin membrane receptor-TFE3-dependent autophagy to enhance the activity of melatonin warrants further attention as a treatment strategy for TSCC.
Melatonin alleviates weanling stress in mice: Involvement of intestinal microbiota J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-20 Wenkai Ren, Peng Wang, Jiameng Yan, Gang Liu, Benhua Zeng, Tarique Hussain, Can Peng, Jie Yin, Tiejun Li, Hong Wei, Guoqiang Zhu, Russel J. Reiter, Bie Tan, Yulong Yin
Abstract Melatonin influences intestinal microbiota and the pathogenesis of various diseases. This study was conducted to explore whether melatonin alleviates weanling stress through intestinal microbiota in a weanling mouse model. Melatonin supplementation in weanling mice (provided in the drinking water at a dosage of 0.2 mg/mL for 2 weeks) significantly improved body weight gain (1.4 ± 0.03 g/day in melatonin group vs 1.2 ± 0.06 g/day in control group) and intestinal morphology (ie, villus length, crypt depth, and villus to crypt ratio), but had little effect on the proliferation or apoptosis of intestinal cells, the numbers of Paneth cells and goblet cells, as well as the expression of makers related to enterocytes (sucrase) and endocrine cells (chromogranin A and peptide YY) in the ileum. Melatonin supplementation had little effect on serum levels of amino acids or stress-related parameters (eg, SOD, TNF-α, and angiotensin I). 16S rRNA sequencing suggested that melatonin supplementation increased the richness indices of intestinal microbiota (observed species, Chao 1, and ACE) and shaped the composition of intestinal microbiota (eg, increase in the abundance of Lactobacillus [19 ± 3% in melatonin group vs 6 ± 2% in control group]), which was demonstrated using an ex vivo proliferation assay and colonic loop proliferation assay. Melatonin supplementation also significantly influenced the metabolism of intestinal microbiota, such as amino acid metabolism and drug metabolism. More importantly, in antibiotic-treated weanling mice and germ-free weanling mice, melatonin failed to affect body weight gain or intestinal morphology. Melatonin significantly reduced (by about 60%) the bacterial load in enterotoxigenic Escherichia coli (ETEC)-infected weanling mice, but had little effect on ETEC load in antibiotic-pretreated animals. In conclusion, melatonin affects body weight gain, intestinal morphology, and intestinal ETEC infection through intestinal microbiota in weanling mice. The findings highlight the importance of intestinal microbiota in mediating the various physiological functions of melatonin in the host.
Melatonin prevents endothelial cell pyroptosis via regulation of long noncoding RNA MEG3/miR-223/NLRP3 axis J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-20 Yong Zhang, Xin Liu, Xue Bai, Yuan Lin, Zhange Li, Jiangbo Fu, Mingqi Li, Tong Zhao, Huan Yang, Ranchen Xu, Jiamin Li, Jin Ju, Benzhi Cai, Chaoqian Xu, Baofeng Yang
Abstract Atherosclerosis (AS) is an inflammatory disease linked to endothelial dysfunction. Melatonin is reported to possess substantial anti-inflammatory properties, which has proven to be effective in AS. Emerging literature suggests that pyroptosis plays a critical role during AS progression. However, whether pyroptosis contributes to endothelial dysfunction and the underlying molecular mechanisms remained unexploited. This study was designed to investigate the antipyroptotic effects of melatonin in atherosclerotic endothelium and to elucidate the potential mechanisms. In this study, high-fat diet (HFD)-treated ApoE−/− mice were used as an atherosclerotic animal model. We found intragastric administration of melatonin for 12 weeks markedly reduced the atherosclerotic plaque in aorta. Meanwhile, melatonin also attenuated the expression of pyroptosis-related genes, including NLRP3, ASC, cleaved caspase1, NF-κB/GSDMD, GSDMD N-termini, IL-1β, and IL-18 in aortic endothelium of melatonin-treated animals. Consistent antipyroptotic effects were also observed in ox-LDL-treated human aortic endothelial cells (HAECs). We found that lncRNA MEG3 enhanced pyroptosis in HAECs. Moreover, MEG3 acted as an endogenous sponge by sequence complementarity to suppress the function of miR-223 and to increase NLRP3 expression and enhance endothelial cell pyroptosis. Furthermore, knockdown of miR-223 blocked the antipyroptotic actions of melatonin in ox-LDL-treated HAECs. Together, our results suggest that melatonin prevents endothelial cell pyroptosis via MEG3/miR-223/NLRP3 axis in atherosclerosis, and therefore, melatonin replacement might be considered a new strategy for protecting endothelium against pyroptosis, thereby for the treatment of atherosclerosis associated with pyroptosis.
Protection of melatonin in experimental models of newborn hypoxic-ischemic brain injury through MT1 receptor J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-23 Bharati Sinha, Qiaofeng Wu, Wei Li, Yanyang Tu, Ana C. Sirianni, Yanchun Chen, Jiying Jiang, Xinmu Zhang, Wu Chen, Shuanhu Zhou, Russel J. Reiter, Simon M. Manning, Nirav J. Patel, Ali M. Aziz-Sultan, Terrie E. Inder, Robert M. Friedlander, Jianfang Fu, Xin Wang
Abstract The function of melatonin as a protective agent against newborn hypoxic-ischemic (H-I) brain injury is not yet well studied, and the mechanisms by which melatonin causes neuroprotection in neurological diseases are still evolving. This study was designed to investigate whether expression of MT1 receptors is reduced in newborn H-I brain injury and whether the protective action of melatonin is by alterations of the MT1 receptors. We demonstrated that there was significant reduction in MT1 receptors in ischemic brain of mouse pups in vivo following H-I brain injury and that melatonin offers neuroprotection through upregulation of MT1 receptors. The role of MT1 receptors was further supported by observation of increased mortality in MT1 knockout mice following H-I brain injury and the reversal of the inhibitory role of melatonin on mitochondrial cell death pathways by the melatonin receptor antagonist, luzindole. These data demonstrate that melatonin mediates its neuroprotective effect in mouse models of newborn H-I brain injury, at least in part, by the restoration of MT1 receptors, the inhibition of mitochondrial cell death pathways and the suppression of astrocytic and microglial activation.
Melatonin improves the fertilization capacity and developmental ability of bovine oocytes by regulating cytoplasmic maturation events J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-11 Xue-Ming Zhao, Na Wang, Hai-Sheng Hao, Chong-Yang Li, Ya-Han Zhao, Chang-Liang Yan, Hao-Yu Wang, Wei-Hua Du, Dong Wang, Yan Liu, Yun-Wei Pang, Hua-Bin Zhu
Abstract Melatonin is a well-characterized antioxidant that has been successfully used to protect oocytes from reactive oxygen species during in vitro maturation (IVM), resulting in improved fertilization capacity and development ability. However, the mechanism via which melatonin improves oocyte fertilization capacity and development ability remains to be determined. Here, we studied the effects of melatonin on cytoplasmic maturation of bovine oocytes. In the present study, bovine oocytes were cultured in IVM medium supplemented with 0, 10–7, 10–9, and 10−11 mol/L melatonin, and the cytoplasmic maturation parameters of MII oocytes after IVM were investigated, including redistribution of organelles (mitochondria, cortical granules [CGs], and endoplasmic reticulum [ER]), intracellular glutathione (GSH) and ATP levels, expression of endogenous antioxidant genes (Cat, Sod1, and GPx), and fertilization-related events (IP3R1 distribution and expression of CD9 and Juno). Our results showed that melatonin significantly improved the cytoplasmic maturation of bovine oocytes by improving the normal distribution of organelles, increasing intracellular GSH and ATP levels, enhancing antioxidant gene expression levels, and modulating fertilization-related events, all of which resulted in increased fertilization capacity and developmental ability. Meanwhile, melatonin also increased the mRNA and protein expression levels of the Tet1 gene and decreased the Dnmt1 gene mRNA and protein levels in bovine oocytes, indicating that melatonin regulates the expression of the detected genes via demethylation. These findings shed insights into the potential mechanisms by which melatonin improves oocyte quality during IVM.
Dynamin-related protein 1-mediated mitochondrial fission contributes to post-traumatic cardiac dysfunction in rats and the protective effect of melatonin J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-11 Mingge Ding, Jiao Ning, Na Feng, Zeyang Li, Zhenhua Liu, Yuanbo Wang, Yueming Wang, Xing Li, Cong Huo, Xin Jia, Rong Xu, Feng Fu, Xiaoming Wang, Jianming Pei
Abstract Mechanical trauma (MT) causes myocardial injury and cardiac dysfunction. However, the underlying mechanism remains largely unclear. This study investigated the role of mitochondrial dynamics in post-traumatic cardiac dysfunction and the protective effects of melatonin. Adult male Sprague Dawley rats were subjected to 5-minute rotations (200 revolutions at a rate of 40 rpm) to induce MT model. Melatonin was administrated intraperitoneally 5 minute after MT. Mitochondrial morphology, myocardial injury, and cardiac function were determined in vivo. There was smaller size of mitochondria and increased number of mitochondria per μm2 in the hearts after MT when the secondary myocardial injury was induced. Melatonin treatment at the dose of 30 mg/kg reduced serine 616 phosphorylation of Drp1 and inhibited mitochondrial Drp1 translocation and mitochondrial fission in the hearts of rats subjected to MT, which contributed to the reduction of myocardial injury and the improvement of cardiac function. In vitro, H9c2 cells cultured in 20% traumatic plasma (TP) for 12 hour showed enhanced mitochondrial fission, mitochondrial membrane potential (∆Ψm) loss, mitochondrial cytochrome c release, and decreased mitochondrial complex I-IV activities. Pretreatment with melatonin (100 μmol/L) efficiently inhibited TP-induced mitochondrial fission, ∆Ψm loss, cytochrome c release, and improved mitochondrial function. Melatonin's protective effects were attributed to its role in suppressing plasma TNF-α overproduction, which was responsible for Drp1-mediated mitochondrial fission. Taken together, our results demonstrate for the first time that abnormal mitochondrial dynamics is involved in post-traumatic cardiac dysfunction. Melatonin has significant pharmacological potential in protecting against MT-induced cardiac dysfunction by preventing excessive mitochondrial fission.
Effects of melatonin on fatty liver disease: The role of NR4A1/DNA-PKcs/p53 pathway, mitochondrial fission, and mitophagy J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-23 Hao Zhou, Wenjuan Du, Ye Li, Chen Shi, Nan Hu, Sai Ma, Weihu Wang, Jun Ren
Abstract Mitochondrial dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) through poorly defined mechanisms. Melatonin supplementation has been found to protect liver function in diabetes and obesity. Here, we intensively explored the role and mechanism of melatonin in the development of NAFLD. We demonstrated that the onset of diet-induced NAFLD greatly caused NR4A1 upregulation in hepatocytes, leading to the activation of DNA-PKcs and p53. On the one hand, p53 aided Drp1 migration in the mitochondria and consequently drove mitochondrial fission. On the other hand, p53 repressed Bnip3 transcription and expression, resulting in mitophagy arrest. The excessive fission and deficient mitophagy dramatically mediated mitochondrial dysfunction, including extensive mPTP opening, reduction in mitochondrial potential, oxidative stress, calcium overload, mitochondrial respiratory collapse, and ATP shortage. However, genetic deletion of NR4A1 or DNA-PKcs could definitively reverse NAFLD progression and the mitochondrial dysfunction. Similarly, melatonin supplementation could robustly reduce the damage to liver and mitochondrial structure and function in NAFLD. Mechanistically, melatonin halted fission but recovered mitophagy via blockade of NR4A1/DNA-PKcs/p53 pathway, finally improving mitochondrial and liver function in the setting of NAFLD. Our results identify NR4A1/DNA-PKcs/p53 pathway as the novel molecular mechanism underlying the pathogenesis of NAFLD via regulation of Drp1-mediated mitochondrial fission and Bnip3-related mitophagy. Meanwhile, we also confirm that melatonin has the ability to cut off the NR4A1/DNA-PKcs/p53 pathway, which confers a protective advantage to hepatocytes and mitochondria. The manipulation of NR4A1/DNA-PKcs/p53 pathway by melatonin highlights a new entry point for treating NAFLD.
Protective role of melatonin in cardiac ischemia-reperfusion injury: from pathogenesis to targeted therapy J. Pineal. Res. (IF 10.391) Pub Date : 2018-01-24 Hao Zhou, Qiang Ma, Pingjun Zhu, Jun Ren, Russel J. Reiter, Yundai Chen
Abstract Acute myocardial infarction (MI) is a major cause of mortality and disability worldwide. In patients with MI, the treatment option for reducing acute myocardial ischemic injury and limiting MI size is timely and effective myocardial reperfusion using either thombolytic therapy or primary percutaneous coronary intervention (PCI). However, the procedure of reperfusion itself induces cardiomyocyte death, known as myocardial reperfusion injury, for which there is still no effective therapy. Recent evidence has depicted a promising role of melatonin, which possesses powerful anti-oxidative and anti-inflammatory properties, in the prevention of ischemia-reperfusion (IR) injury and the protection against cardiomyocyte death. A number of reports explored the mechanism of action behind melatonin-induced beneficial effects against myocardial IR injury. In this review, we summarize the research progress related to IR injury and discuss the unique actions of melatonin as a protective agent. Furthermore, the possible mechanisms responsible for the myocardial benefits of melatonin against reperfusion injury are listed with the prospect of the use of melatonin in clinical application. This article is protected by copyright. All rights reserved.
Melatonin redirects carbohydrates metabolism during sugar starvation in plant cells J. Pineal. Res. (IF 10.391) Pub Date : 2018-01-02 Agnieszka Kobylińska, Sławomir Borek, Małgorzata M. Posmyk
Abstract Recent studies have shown that melatonin is an important molecule in plant physiology. It seems that the most important is that melatonin efficacy eliminates oxidative stress (direct and indirect antioxidant) and moreover induce plant stress reaction and switch on different defence strategies (preventively and interventively actions). In this report the impact of exogenous melatonin on carbohydrate metabolism in Nicotiana tabacum L. line Bright Yellow 2 (BY-2) suspension cells during sugar starvation was examined. We analysed starch concentration, α-amylase and PEPCK activity as well as proteolytic activity in culture media. It has been shown that BY-2 cell treatment with 200 nM of melatonin, improved viability of sugar-starved cells. It was correlated with higher starch content and phosphoenolpyruvate carboxykinase (PEPCK) activity. The obtained results revealed that exogenous melatonin under specific conditions (stress) can play regulatory role in sugar metabolism and it may modulate carbohydrate concentration in etiolated BY-2 cells. Moreover, our results confirmed the hypothesis that if the starch is synthesized even in sugar-starved cells, it is highly probable that melatonin shifts the BY-2 cell metabolism on gluconeogenesis pathway and allows for synthesis of carbohydrates from non-sugar precursors i.e. amino acids. This points to another defence strategy that was induced by exogenous melatonin applied in plants to overcome adverse environmental conditions. This article is protected by copyright. All rights reserved.
Biological Effects of Melatonin on Osteoblast/Osteoclast Co-cultures, Bone and Quality of Life: implications of a role for MT2 melatonin receptors, MEK1/2 and MEK5 in melatonin-mediated osteoblastogenesis J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-28 Sifat Maria, Rebekah M. Samsonraj, Fahima Munmun, Jessica Glas, Maria Silvestros, Mary P. Kotlarczyk, Ryan Rylands, Amel Dudakovic, Andre J. van Wijnen, Larry T. Enderby, Holly Lassila, Bala Dodda, Vicki L. Davis, Judy Balk, Matt Burow, Bruce A. Bunnell, Paula A. Witt-Enderby
Abstract The Melatonin Osteoporosis Prevention Study (MOPS) demonstrated that nightly melatonin resulted in a time-dependent decrease in equilibrium ratios of serum osteoclasts and osteoblasts in perimenopausal women. This study examines mechanisms related to the ratios of osteoblasts and osteoclasts using co-culture models (transwell or layered) of human mesenchymal stem cell (MSCs) and human peripheral blood monocytes (PBMCs). Human MSCs/PBMCs co-cultures exposed to melatonin in osteogenic (OS+) medium for 21 days induced osteoblast differentiation and mineralization; however, only in layered co-cultures did melatonin inhibit osteoclastogenesis. Melatonin effects were mediated through MT2 melatonin receptors, MEK1/2 and MEK5. In layered but not transwell co-cultures, melatonin increased OPG:RANKL ratios by inhibiting RANKL, suggesting that contact with osteoclasts during osteoblastogenesis inhibits RANKL secretion. Melatonin modulated expression of ERK1/2, ERK5, β1 integrin, GLUT4 and IRβ expression that was dependent upon the type of co-culture; however, in both cultures, melatonin increased RUNX2 and decreased PPARγ expression, indicating a role for metabolic processes that control osteogenic versus adipogenic cell fates of MSCs. Furthermore, melatonin also has osteoblast-inducing effects on human adipose-derived MSCs. In vivo, one-year nightly melatonin (15mg/L) given to neu female mice in their drinking water, increased pErk1/2, pErk5, Runx2 and Opg and Rankl levels in bone consistent with melatonin's already reported bone-enhancing effects. Finally, analysis of daily logs from the MOPS demonstrated a significant improvement in mood and perhaps sleep quality in women receiving melatonin vs. placebo. The osteoblast-inducing, bone-enhancing effects of melatonin and improvement in quality of life suggests that melatonin is a safe and effective bone loss therapy. This article is protected by copyright. All rights reserved.
Prophylactic Supplement with Melatonin Successfully Suppresses the Pathogenesis of Periodontitis through Normalizing RANKL/OPG Ratio and Depressing the TLR4/MyD88 Signaling Pathway J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-23 Ting-Yi Renn, Yung-Kai Huang, Sheng-Wei Feng, Hsiao-Wei Wang, Wei-Fang Lee, Che-Tong Lin, Thierry Burnouf, Li-You Chen, Pan-Fu Kao, Hung-Ming Chang
Abstract Periodontitis (PD) is an inflammatory disease characterized by gingival inflammation and resorption of alveolar bone. Impaired receptor activator of nuclear factor-kappa B ligand/osteoprotegerin (RANKL/OPG) signaling caused by enhanced production of pro-inflammatory cytokines plays an essential role in the pathogenesis of PD. Considering melatonin possesses significant anti-inflammatory property, present study aims to determine whether prophylactic treatment with melatonin would effectively normalize RANKL/OPG signaling, depress toll-like receptor 4/myeloid differentiation factor 88 (TLR4/MyD88) mediated pro-inflammatory cytokine activation, and successfully suppress the pathogenesis of PD. PD was induced in adult rats by placing the ligature at molar subgingival regions. Fourteen days before PD induction, 10, 50, or 100 mg/kg of melatonin were intraperitoneally injected for consecutive 28 days. Biochemical and enzyme-linked immunosorbent assay were used to detect TLR4/MyD88 activity, RANKL, OPG, interleukin 1β, interleukin 6, and tumor necrosis factor-α levels, respectively. The extent of bone loss, bone mineral intensity, and calcium intensity were further evaluated by scanning electron microscopy, micro-computed tomography and energy-dispersive X-ray spectroscopy. Results indicated that high RANKL/OPG ratio, TLR4/MyD88 activity and pro-inflammatory cytokine levels were detected following PD. Impaired biochemical findings paralleled well with severe bone loss and reduced calcium intensity. However, in rats pre-treated with melatonin, all above parameters were successfully returned to nearly normal levels with maximal change observed in rats receiving 100 mg/kg. As prophylactic treatment with melatonin effectively normalizes RANKL/OPG signaling by depressing TLR4/MyD88 mediated pro-inflammatory cytokine production, dietary supplement with melatonin may serve as an advanced strategy to strengthen oral health to counteract PD-induced destructive damage. This article is protected by copyright. All rights reserved.
Nocturnal activation of melatonin receptor type 1 signaling modulates diurnal insulin sensitivity via regulation of PI3K activity J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-16 Sharon Owino, Aida Sánchez-Bretaño, Cynthia Tchio, Erika Cecon, Angeliki Karamitri, Julie Dam, Ralf Jockers, Giuseppe Piccione, Hye Lim Noh, Taekyoon Kim, Jason K. Kim, Kenkichi Baba, Gianluca Tosini
Recent genetic studies have highlighted the potential involvement of melatonin receptor 1 (MT1) and melatonin receptor 2 (MT2) in the pathogenesis of type 2 diabetes. Here we report that mice lacking MT1 (MT1 KO) tend to accumulate more fat mass than WT mice and exhibit marked systemic insulin resistance. Additional experiments revealed that the main insulin signaling pathway affected by the loss of MT1 was the activation of phosphatidylinositol-3-kinase (PI3K). Transcripts of both catalytic and regulatory subunits of PI3K were strongly down-regulated within MT1 KO mice. Moreover, the suppression of nocturnal melatonin levels within WT mice, by exposing mice to constant light, resulted in impaired PI3K activity and insulin resistance during the day, similar to what was observed in MT1 KO mice. Inversely, administration of melatonin to WT mice exposed to constant light, was sufficient and necessary to restore insulin mediated PI3K activity and insulin sensitivity. Hence our data demonstrate that the activation of MT1 signaling at night modulates insulin sensitivity during the day via the regulation of the PI3K transcription and activity. Lastly we provide evidence that decreased expression of MTNR1A (MT1) in the liver of diabetic individuals is associated with poorly controlled diabetes. This article is protected by copyright. All rights reserved.
Combination of melatonin and rapamycin for head and neck cancer therapy: Suppression of AKT/mTOR pathway activation, and activation of mitophagy and apoptosis via mitochondrial function regulation J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-16 Ying-Qiang Shen, Ana Guerra-Librero, Beatriz I Fernandez-Gil, Javier Florido, Sergio García-López, Laura Martinez-Ruiz, Miguel Mendivil-Perez, Viviana Soto-Mercado, Darío Acuña-Castroviejo, Hector Ortega-Arellano, Victor Carriel, María E Diaz-Casado, Russel J Reiter, Iryna Rusanova, Ana Nieto, Luis C López, Germaine Escames
Head and neck squamous cell carcinoma (HNSCC) clearly involves activation of the Akt mammalian target of rapamycin (mTOR) signalling pathway. However, the effectiveness of treatment with the mTOR inhibitor rapamycin is often limited by chemoresistance. Melatonin suppresses neoplastic growth via different mechanisms in a variety of tumours. In the present study, we aimed to elucidate the effects of melatonin on rapamycin-induced HNSCC cell death, and to identify potential cross-talk pathways. We analysed the dose-dependent effects of melatonin in rapamycin-treated HNSCC cell lines (Cal-27 and SCC-9). These cells were treated with 0.1, 0.5, or 1 mM melatonin combined with 20 nM rapamycin. We further examined the potential synergistic effects of melatonin with rapamycin in Cal-27 xenograft mice. Relationships between inhibition of the mTOR pathway, reactive oxygen species (ROS), and apoptosis and mitophagy reportedly increased the cytotoxic effects of rapamycin in HNSCC. Our results demonstrated that combined treatment with rapamycin and melatonin blocked the negative feedback loop from the specific downstream effector of mTOR activation S6K1 to Akt signalling, which decreased cell viability, proliferation, and clonogenic capacity. Interestingly, combined treatment with rapamycin and melatonin induced changes in mitochondrial function, which were associated with increased ROS production, increasing apoptosis and mitophagy. This led to increase cell death and cellular differentiation. Our data further indicated that melatonin administration reduced rapamycin-associated toxicity to healthy cells. Overall, our findings suggested that melatonin could be used as an adjuvant agent with rapamycin, improving effectiveness while minimizing its side effects. This article is protected by copyright. All rights reserved.
Rice histone deacetylase 10 and Arabidopsis histone deacetylase 14 genes encode N-acetylserotonin deacetylase, which catalyzes conversion of N-acetylserotonin into serotonin, a reverse reaction for melatonin biosynthesis in plants J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-16 Kyungjin Lee, Hyoung Yool Lee, Kyoungwhan Back
In plants, melatonin production is strictly regulated, unlike the production of its precursor, serotonin, which is highly inducible in response to stimuli, such as senescence and pathogen exposure. Exogenous serotonin treatment does not greatly induce the production of N-acetylserotonin (NAS) and melatonin in plants, which suggests the possible existence of one or more regulatory genes in the pathway for the biosynthesis of melatonin from serotonin. In this report, we found that NAS was rapidly and abundantly converted into serotonin in rice seedlings, indicating the presence of an N-acetylserotonin deacetylase (ASDAC). To clone the putative ASDAC gene, we screened four genes that were known as histone deacetylase (HDAC) genes, but encoded proteins targeted into chloroplasts or mitochondria rather than nuclei. Of four recombinant Escherichia coli strains expressing these genes, one E. coli strain expressing the rice HDAC10 gene was found to be capable of producing serotonin in response to treatment with NAS. The recombinant purified rice HDAC10 (OsHDAC10) protein exhibited ASDAC enzyme activity toward NAS, N-acetyltyramine (NAT), N-acetyltryptamine, and melatonin, with the highest ASDAC activity for NAT. In addition, its Arabidopsis ortholog, AtHDAC14, showed similar ASDAC activity to that of OsHDAC10. Both OsHDAC10 and AtHDAC14 were found to be expressed in chloroplasts. Phylogenetic analysis indicated that ASDAC homologs were present in archaea, but not in cyanobacteria, which differs from the distribution of serotonin N-acetyltransferase (SNAT). This suggests that SNAT and ASDAC may have evolved differently from ancestral eukaryotic cells. This article is protected by copyright. All rights reserved.
Melatonin prevents hypochlorous acid mediated cyanocobalamin destruction and cyanogen chloride generation J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-16 Roohi Jeelani, Dhiman Maitra, Charalampos Chatzicharalampous, Syed Najeemuddin, Robert T. Morris, Husam M. Abu-Soud
Hypochlorous acid (HOCl) is a potent cytotoxic oxidant generated by the enzyme myeloperoxidase (MPO) in the presence of hydrogen peroxide (H2O2) and chloride (Cl-). Elevated levels of HOCl play an important role in various pathological conditions through oxidative modification of several biomolecules. Recently, we have highlighted the ability of HOCl to mediate the destruction of the metal-ion derivatives of tetrapyrrole macrocyclic rings such as hemoproteins and vitamin B12 (VB12) derivatives. Destruction of cyanocobalamin, a common pharmacological form of VB12 mediated by HOCl, results in the generation of toxic molecular products such as chlorinated derivatives, corrin ring cleavage products, the toxic blood agents cyanide (CN-) and cyanogen chloride (CNCl), and redox active free cobalt. Here, we show that melatonin prevents HOCl-mediated cyanocobalamin destruction, using a combination of UV-Vis spectrophotometry, HPLC analysis, and colorimetric CNCl assay. Identification of several melatonin oxidation products suggests that the protective role of melatonin against HOCl-mediated cyanocobalamin destruction and subsequent CNCl generation is at the expense of melatonin oxidation. Collectively, this work highlights that, in addition to acting as an antioxidant and as a MPO inhibitor, melatonin can also prevent VB12 deficiency in inflammatory conditions such as cardiovascular and neurodegenerative diseases, among many others. This article is protected by copyright. All rights reserved.
Melatonin improves the meiotic maturation of porcine oocytes by reducing endoplasmic reticulum stress during in vitro maturation J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-04 Hyo-Jin Park, Jae-Young Park, Jin-Woo Kim, Seul-Gi Yang, Jae-Min Jung, Min-Ji Kim, Man-Jong Kang, Young Ho Cho, Gabbine Wee, Hee-Young Yang, Bong-Seok Song, Sun-Uk Kim, Deog-Bon Koo
Under endoplasmic reticulum (ER)-stress conditions, the unfolded protein response (UPR) generates a defense mechanism in mammalian cells. The regulation of UPR signaling is important in oocyte maturation, embryo development, and female reproduction of pigs. Recent studies have shown that melatonin plays an important role as an antioxidant to improve pig oocyte maturation. However, there is no report on the role of melatonin in the regulation of UPR signaling and ER-stress during in vitro maturation (IVM) of porcine oocytes. Therefore, the objective of this study was to investigate the antioxidative effects of melatonin on porcine oocyte maturation through the regulation of ER-stress and UPR signaling. We investigated the changes in the mRNA/protein expression levels of three UPR signal genes (Bip/Grp78, ATF4, P90/50ATF6, sXbp1, and CHOP) on oocytes, cumulus cells, and cumulus-oocyte complexes (COCs) during IVM (metaphase I; 22 hours and metaphase II; 44 hours) by Western blot and reverse transcription-polymerase chain reaction analysis. Treatment with the ER-stress inducer, tunicamycin (Tm), significantly increased expression of UPR markers. Additionally, cumulus cell expansion and meiotic maturation of oocytes were reduced in COCs of Tm-treated groups (1, 5, and 10 μg/mL). We confirmed the reducing effects of melatonin (0.1 μmol/L) on ER-stress after pretreatment with Tm (5 μg/mL; 22 hours) in maturing COCs. Addition of melatonin (0.1 μmol/L) to Tm-pretreated COCs recovered meiotic maturation rates and expression of most UPR markers. In conclusion, we confirmed a role for melatonin in the modulation of UPR signal pathways and reducing ER-stress during IVM of porcine oocytes.
RAV transcription factors are essential for disease resistance against cassava bacterial blight via activation of melatonin biosynthesis genes J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-04 Yunxie Wei, Yanli Chang, Hongqiu Zeng, Guoyin Liu, Chaozu He, Haitao Shi
With 1 AP2 domain and 1 B3 domain, 7 MeRAVs in apetala2/ethylene response factor (AP2/ERF) gene family have been identified in cassava. However, the in vivo roles of these remain unknown. Gene expression assays showed that the transcripts of MeRAVs were commonly regulated after Xanthomonas axonopodis pv manihotis (Xam) and MeRAVs were specifically located in plant cell nuclei. Through virus-induced gene silencing (VIGS) in cassava, we found that MeRAV1 and MeRAV2 are essential for plant disease resistance against cassava bacterial blight, as shown by the bacterial propagation of Xam in plant leaves. Through VIGS in cassava leaves and overexpression in cassava leave protoplasts, we found that MeRAV1 and MeRAV2 positively regulated melatonin biosynthesis genes and the endogenous melatonin level. Further investigation showed that MeRAV1 and MeRAV2 are direct transcriptional activators of 3 melatonin biosynthesis genes in cassava, as evidenced by chromatin immunoprecipitation-PCR in cassava leaf protoplasts and electrophoretic mobility shift assay. Moreover, cassava melatonin biosynthesis genes also positively regulated plant disease resistance. Taken together, this study identified MeRAV1 and MeRAV2 as common and upstream transcription factors of melatonin synthesis genes in cassava and revealed a model of MeRAV1 and MeRAV2-melatonin biosynthesis genes-melatonin level in plant disease resistance against cassava bacterial blight.
Melatonin alleviates low PS I-limited carbon assimilation under elevated CO2 and enhances the cold tolerance of offspring in chlorophyll b-deficient mutant wheat J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-04 Xiangnan Li, Marian Brestic, Dun-Xian Tan, Marek Zivcak, Xiancan Zhu, Shengqun Liu, Fengbin Song, Russel J. Reiter, Fulai Liu
Melatonin is involved in the regulation of carbohydrate metabolism and induction of cold tolerance in plants. The objective of this study was to investigate the roles of melatonin in modulation of carbon assimilation of wild-type wheat and the Chl b-deficient mutant ANK32B in response to elevated CO2 concentration ([CO2]) and the transgenerational effects of application of exogenous melatonin (hereafter identified as melatonin priming) on the cold tolerance in offspring. The results showed that the melatonin priming enhanced the carbon assimilation in ANK32B under elevated [CO2], via boosting the activities of ATPase and sucrose synthesis and maintaining a relatively higher level of total chlorophyll concentration in leaves. In addition, melatonin priming in maternal plants at grain filling promoted the seed germination in offspring by accelerating the starch degradation and improved the cold tolerance of seedlings through activating the antioxidant enzymes and enhancing the photosynthetic electron transport efficiency. These findings suggest the important roles of melatonin in plant response to future climate change, indicating that the melatonin priming at grain filling in maternal plants could be an effective approach to improve cold tolerance of wheat offspring at seedling stage.
Melatonin alleviates adipose inflammation through elevating α-ketoglutarate and diverting adipose-derived exosomes to macrophages in mice J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-04 Zhenjiang Liu, Lu Gan, Tiantian Zhang, Qian Ren, Chao Sun
Obesity is associated with macrophage infiltration and metabolic inflammation, both of which promote metabolic disease progression. Melatonin is reported to possess anti-inflammatory properties by inhibiting inflammatory response of adipocytes and macrophages activation. However, the effects of melatonin on the communication between adipocytes and macrophages during adipose inflammation remain elusive. Here, we demonstrated melatonin alleviated inflammation and elevated α-ketoglutarate (αKG) level in adipose tissue of obese mice. Mitochondrial isocitrate dehydrogenase 2 (Idh2) mRNA level was also elevated by melatonin in adipocytes leading to increase αKG level. Further analysis revealed αKG was the target for melatonin inhibition of adipose inflammation. Moreover, sirtuin 1 (Sirt1) physically interacted with IDH2 and formed a complex to increase the circadian amplitude of Idh2 and αKG content in melatonin-inhibited adipose inflammation. Notably, melatonin promoted exosomes secretion from adipocyte and increased adipose-derived exosomal αKG level. Our results also confirmed that melatonin alleviated adipocyte inflammation and increased ratio of M2 to M1 macrophages by transporting of exosomal αKG to macrophages and promoting TET-mediated DNA demethylation. Furthermore, exosomal αKG attenuated signal transducers and activators of transduction-3 (STAT3)/NF-κB signal by its receptor oxoglutarate receptor 1 (OXGR1) in adipocytes. Melatonin also attenuated adipose inflammation and deceased macrophage number in chronic jet-lag mice. In summary, our results demonstrate melatonin alleviates metabolic inflammation by increasing cellular and exosomal αKG level in adipose tissue. Our data reveal a novel function of melatonin on adipocytes and macrophages communication, suggesting a new potential therapy for melatonin to prevent and treat obesity caused systemic inflammatory disease.
Neuroprotective effects of melatonin on amphetamine-induced dopaminergic fiber degeneration in the hippocampus of postnatal rats J. Pineal. Res. (IF 10.391) Pub Date : 2017-12-04 Tanawan Leeboonngam, Ratchadaporn Pramong, Kwankanit Sae-ung, Piyarat Govitrapong, Pansiri Phansuwan-Pujito
Chronic amphetamine (AMPH) abuse leads to damage of the hippocampus, the brain area associated with learning and memory process. Previous results have shown that AMPH-induced dopamine neurotransmitter release, reactive oxygen species formation, and degenerative protein aggregation lead to neuronal death. Melatonin, a powerful antioxidant, plays a role as a neuroprotective agent. The objective of this study was to investigate whether the protective effect of melatonin on AMPH-induced hippocampal damage in the postnatal rat acts through the dopaminergic pathway. Four-day-old postnatal rats were subcutaneously injected with 5-10 mg/kg AMPH and pretreated with 10 mg/kg melatonin prior to AMPH exposure for seven days. The results showed that melatonin decreased the AMPH-induced hippocampal neuronal degeneration in the dentate gyrus, CA1, and CA3. Melatonin attenuated the reduction in the expression of hippocampal synaptophysin, PSD-95, α-synuclein, and N-methyl-D-aspartate (NMDA) receptor protein and mRNA caused by AMPH. Melatonin attenuated the AMPH-induced reduction in dopamine transporter (DAT) protein expression in the hippocampus and the reduction in mRNA expression in the ventral tegmental area (VTA). Immunofluorescence demonstrated that melatonin not only prevented the AMPH-induced loss of DAT and NMDA receptor but also prevented AMPH-induced α-synuclein overexpression in the dentate gyrus, CA1, and CA3. Melatonin decreased the AMPH-induced reduction in the protein and mRNA of the NMDA receptor downstream signaling molecule, calcium/calmodulin-dependent protein kinase II (CaMKII), and the melatonin receptors (MT1 and MT2). This study showed that melatonin prevented AMPH-induced toxicity in the hippocampus of postnatal rats possibly via its antioxidative effect and mitochondrial protection.
Protection of melatonin in experimental models of newborn hypoxic-ischemic brain injury through MT1 receptor J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-23 Bharati Sinha, Qiaofeng Wu, Wei Li, Yanyang Tu, Ana C. Sirianni, Yanchun Chen, Jiying Jiang, Xinmu Zhang, Wu Chen, Shuanhu Zhou, Russel J. Reiter, Simon M. Manning, Nirav J. Patel, Ali M. Aziz-Sultan, Terrie E. Inder, Robert M. Friedlander, Jianfang Fu, Xin Wang
The function of melatonin as a protective agent against newborn hypoxic-ischemic (H-I) brain injury is not yet well studied, and the mechanisms by which melatonin causes neuroprotection in neurological diseases are still evolving. This study was designed to investigate whether expression of MT1 receptors is reduced in newborn H-I brain injury and whether the protective action of melatonin is by alterations of the MT1 receptors. We demonstrated that there was significant reduction in MT1 receptors in ischemic brain of mouse pups in vivo following H-I brain injury and that melatonin offers neuroprotection through upregulation of MT1 receptors. The role of MT1 receptors was further supported by observation of increased mortality in MT1 knockout mice following H-I brain injury and the reversal of the inhibitory role of melatonin on mitochondrial cell death pathways by the melatonin receptor antagonist, luzindole. These data demonstrate that melatonin mediates its neuroprotective effect in mouse models of newborn H-I brain injury, at least in part, by the restoration of MT1 receptors, the inhibition of mitochondrial cell death pathways and the suppression of astrocytic and microglial activation.
Effects of melatonin on fatty liver disease: The role of NR4A1/DNA-PKcs/p53 pathway, mitochondrial fission, and mitophagy J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-23 Hao Zhou, Wenjuan Du, Ye Li, Chen Shi, Nan Hu, Sai Ma, Weihu Wang, Jun Ren
Mitochondrial dysfunction has been implicated in the pathogenesis of nonalcoholic fatty liver disease (NAFLD) through poorly defined mechanisms. Melatonin supplementation has been found to protect liver function in diabetes and obesity. Here, we intensively explored the role and mechanism of melatonin in the development of NAFLD. We demonstrated that the onset of diet-induced NAFLD greatly caused NR4A1 upregulation in hepatocytes, leading to the activation of DNA-PKcs and p53. On the one hand, p53 aided Drp1 migration in the mitochondria and consequently drove mitochondrial fission. On the other hand, p53 repressed Bnip3 transcription and expression, resulting in mitophagy arrest. The excessive fission and deficient mitophagy dramatically mediated mitochondrial dysfunction, including extensive mPTP opening, reduction in mitochondrial potential, oxidative stress, calcium overload, mitochondrial respiratory collapse, and ATP shortage. However, genetic deletion of NR4A1 or DNA-PKcs could definitively reverse NAFLD progression and the mitochondrial dysfunction. Similarly, melatonin supplementation could robustly reduce the damage to liver and mitochondrial structure and function in NAFLD. Mechanistically, melatonin halted fission but recovered mitophagy via blockade of NR4A1/DNA-PKcs/p53 pathway, finally improving mitochondrial and liver function in the setting of NAFLD. Our results identify NR4A1/DNA-PKcs/p53 pathway as the novel molecular mechanism underlying the pathogenesis of NAFLD via regulation of Drp1-mediated mitochondrial fission and Bnip3-related mitophagy. Meanwhile, we also confirm that melatonin has the ability to cut off the NR4A1/DNA-PKcs/p53 pathway, which confers a protective advantage to hepatocytes and mitochondria. The manipulation of NR4A1/DNA-PKcs/p53 pathway by melatonin highlights a new entry point for treating NAFLD.
Melatonin improves the fertilization capacity and developmental ability of bovine oocytes by regulating cytoplasmic maturation events J. Pineal. Res. (IF 10.391) Pub Date : 2017-10-11 Xue-Ming Zhao, Na Wang, Hai-Sheng Hao, Chong-Yang Li, Ya-Han Zhao, Chang-Liang Yan, Hao-Yu Wang, Wei-Hua Du, Dong Wang, Yan Liu, Yun-Wei Pang, Hua-Bin Zhu
Melatonin is a well-characterized antioxidant that has been successfully used to protect oocytes from reactive oxygen species during in vitro maturation (IVM), resulting in improved fertilization capacity and development ability. However, the mechanism via which melatonin improves oocyte fertilization capacity and development ability remains to be determined. Here, we studied the effects of melatonin on cytoplasmic maturation of bovine oocytes. In the present study, bovine oocytes were cultured in IVM medium supplemented with 0, 10–7, 10–9, and 10−11 mol/L melatonin, and the cytoplasmic maturation parameters of MII oocytes after IVM were investigated, including redistribution of organelles (mitochondria, cortical granules [CGs], and endoplasmic reticulum [ER]), intracellular glutathione (GSH) and ATP levels, expression of endogenous antioxidant genes (Cat, Sod1, and GPx), and fertilization-related events (IP3R1 distribution and expression of CD9 and Juno). Our results showed that melatonin significantly improved the cytoplasmic maturation of bovine oocytes by improving the normal distribution of organelles, increasing intracellular GSH and ATP levels, enhancing antioxidant gene expression levels, and modulating fertilization-related events, all of which resulted in increased fertilization capacity and developmental ability. Meanwhile, melatonin also increased the mRNA and protein expression levels of the Tet1 gene and decreased the Dnmt1 gene mRNA and protein levels in bovine oocytes, indicating that melatonin regulates the expression of the detected genes via demethylation. These findings shed insights into the potential mechanisms by which melatonin improves oocyte quality during IVM.
Melatonin limits paclitaxel-induced mitochondrial dysfunction in vitro and protects against paclitaxel-induced neuropathic pain in the rat J. Pineal. Res. (IF 10.391) Pub Date : 2017-09-22 Helen F. Galley, Barry McCormick, Kirsten L. Wilson, Damon A. Lowes, Lesley Colvin, Carole Torsney
Chemotherapy-induced neuropathic pain is a debilitating and common side effect of cancer treatment. Mitochondrial dysfunction associated with oxidative stress in peripheral nerves has been implicated in the underlying mechanism. We investigated the potential of melatonin, a potent antioxidant that preferentially acts within mitochondria, to reduce mitochondrial damage and neuropathic pain resulting from the chemotherapeutic drug paclitaxel. In vitro, paclitaxel caused a 50% reduction in mitochondrial membrane potential and metabolic rate, independent of concentration (20-100 μmol/L). Mitochondrial volume was increased dose-dependently by paclitaxel (200% increase at 100 μmol/L). These effects were prevented by co-treatment with 1 μmol/L melatonin. Paclitaxel cytotoxicity against cancer cells was not affected by co-exposure to 1 μmol/L melatonin of either the breast cancer cell line MCF-7 or the ovarian carcinoma cell line A2780. In a rat model of paclitaxel-induced painful peripheral neuropathy, pretreatment with oral melatonin (5/10/50 mg/kg), given as a daily bolus dose, was protective, dose-dependently limiting development of mechanical hypersensitivity (19/43/47% difference from paclitaxel control, respectively). Melatonin (10 mg/kg/day) was similarly effective when administered continuously in drinking water (39% difference). Melatonin also reduced paclitaxel-induced elevated 8-isoprostane F2α levels in peripheral nerves (by 22% in sciatic; 41% in saphenous) and limited paclitaxel-induced reduction in C-fibre activity-dependent slowing (by 64%). Notably, melatonin limited the development of mechanical hypersensitivity in both male and female animals (by 50/41%, respectively), and an additive effect was found when melatonin was given with the current treatment, duloxetine (75/62% difference, respectively). Melatonin is therefore a potential treatment to limit the development of painful neuropathy resulting from chemotherapy treatment.
Melatonin limits paclitaxel-induced mitochondrial dysfunction in vitro and protects against paclitaxel-induced neuropathic pain in the rat J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-22 Helen F. Galley, Barry McCormick, Kirsten L. Wilson, Damon A. Lowes, Lesley Colvin, Carole Torsney
Chemotherapy-induced neuropathic pain is a debilitating and common side effect of cancer treatment. Mitochondrial dysfunction associated with oxidative stress in peripheral nerves has been implicated in the underlying mechanism. We investigated the potential of melatonin, a potent antioxidant that preferentially acts within mitochondria, to reduce mitochondrial damage and neuropathic pain resulting from the chemotherapeutic drug paclitaxel. In vitro, paclitaxel caused a 50% reduction of mitochondrial membrane potential and metabolic rate, independent of concentration (20-100μM). Mitochondrial volume was increased dose-dependently by paclitaxel (200% increase at 100μM). These effects were prevented by co-treatment with 1μM melatonin. Paclitaxel cytotoxicity against cancer cells was not affected by co-exposure to 1μM melatonin of either the breast cancer cell line MCF-7, or the ovarian carcinoma cell line A2780. In a rat model of paclitaxel-induced painful peripheral neuropathy, pre-treatment with oral melatonin (5/10/50mg/kg), given as a daily bolus dose, was protective, dose-dependently limiting development of mechanical hypersensitivity (19/43/47% difference from paclitaxel control, respectively). Melatonin (10mg/kg/day) was similarly effective when administered continuously in drinking water (39% difference). Melatonin also reduced paclitaxel-induced elevated 8-isoprostane F2α levels in peripheral nerves (by 22% in sciatic; 41% in saphenous) and limited paclitaxel-induced reduction of C fibre activity-dependent slowing (by 64%). Notably melatonin limited the development of mechanical hypersensitivity in both male and female animals (by 50/41%, respectively) and an additive effect was found when melatonin was given with the current treatment, duloxetine (75/62% difference, respectively). Melatonin is therefore a potential treatment to limit the development of painful neuropathy resulting from chemotherapy treatment.
Maternal administration of melatonin exerts short- and long-term neuroprotective effects on the offspring from lipopolysaccharide-treated mice J. Pineal. Res. (IF 10.391) Pub Date : 2017-09-06 Ana Paula Domínguez Rubio, Fernando Correa, Julieta Aisemberg, Damián Dorfman, María Victoria Bariani, Ruth Estela Rosenstein, María Zorrilla Zubilete, Ana María Franchi
Preterm birth is a major contributor to early and delayed physical and cognitive impairment. Epidemiological and experimental data indicate that maternal infections are a significant and preventable cause of preterm birth. Recently, melatonin has been suggested to exert neuroprotective effects in several models of brain injury. Here, we sought to investigate whether the administration of melatonin is able to prevent lipopolysaccharide (LPS)-induced fetal brain damage in a model of LPS-induced preterm labor. For this purpose, 15-day pregnant BALB/c mice received intraperitoneally 2 doses of LPS or vehicle: the first one at 10:00 hours (0.26 mg/kg) and the second at 13:00 hours (0.52 mg/kg). On day 14 of pregnancy, a group of mice was subcutaneously implanted with a pellet of 25 mg melatonin. This experimental protocol resulted in 100% of preterm birth and pup death in the LPS group and a 50% of term birth and pup survival in the melatonin + LPS group. In the absence of melatonin, fetuses from LPS-treated mothers showed histological signs of brain damage, microglial/macrophage activation, and higher levels of IL-1β, inducible nitric oxide synthase (NOS), and neuronal NOS mRNAs as well as increased histone acetyltransferase activity and histone H3 hyperacetylation. In contrast, antenatal administration of melatonin prevented LPS-induced fetal brain damage. Moreover, when behavioral traits were analyzed in the offspring from control, melatonin, and melatonin + LPS, no significant differences were found, suggesting that melatonin prevented LPS-induced long-term neurodevelopmental impairments. Collectively, our results suggest that melatonin could be a new therapeutic tool to prevent fetal brain damage and its long-term consequences induced by maternal inflammation.
Melatonin ameliorates hypoglycemic stress-induced brain endothelial tight junction injury by inhibiting protein nitration of TP53-induced glycolysis and apoptosis regulator J. Pineal. Res. (IF 10.391) Pub Date : 2017-09-06 Cheng-kun Wang, Muhammad Masood Ahmed, Quan Jiang, Nan-nan Lu, Chao Tan, Yin-ping Gao, Qaisar Mahmood, Dan-yang Chen, Kohji Fukunaga, Mei Li, Zhong Chen, Christopher S. Wilcox, Ying-mei Lu, Zheng-hong Qin, Feng Han
Severe hypoglycemia has a detrimental impact on the cerebrovasculature, but the molecular events that lead to the disruption of the integrity of the tight junctions remain unclear. Here, we report that the microvessel integrity was dramatically compromised (59.41% of wild-type mice) in TP53-induced glycolysis and apoptosis regulator (TIGAR) transgenic mice stressed by hypoglycemia. Melatonin, a potent antioxidant, protects against hypoglycemic stress-induced brain endothelial tight junction injury in the dosage of 400 nmol/L in vitro. FRET (fluorescence resonance energy transfer) imaging data of endothelial cells stressed by low glucose revealed that TIGAR couples with calmodulin to promote TIGAR tyrosine nitration. A tyrosine 92 mutation interferes with the TIGAR-dependent NADPH generation (55.60% decreased) and abolishes its protective effect on tight junctions in human brain microvascular endothelial cells. We further demonstrate that the low-glucose-induced disruption of occludin and Caludin5 as well as activation of autophagy was abrogated by melatonin-mediated blockade of nitrosative stress in vitro. Collectively, we provide information on the detailed molecular mechanisms for the protective actions of melatonin on brain endothelial tight junctions and suggest that this indole has translational potential for severe hypoglycemia-induced neurovascular damage.
Cadmium-induced melatonin synthesis in rice requires light, hydrogen peroxide, and nitric oxide: Key regulatory roles for tryptophan decarboxylase and caffeic acid O-methyltransferase J. Pineal. Res. (IF 10.391) Pub Date : 2017-09-06 Kyungjin Lee, Geun-Hee Choi, Kyoungwhan Back
In plants, melatonin production is induced by stimuli such as cold and drought, and cadmium (Cd) is the best elicitor of melatonin production in rice. However, the mechanism by which Cd induces melatonin synthesis in plants remains unknown. We challenged rice seedlings with Cd under different light conditions and found that continuous light produced the highest levels of melatonin, while continuous dark failed to induce melatonin production. Transcriptional and translational induction of tryptophan decarboxylase contributed to the light induction of melatonin during Cd treatment, whereas the protein level of light-induced caffeic acid O-methyltransferase (COMT) was decreased by Cd treatment. In analogy, COMT enzyme activity was inhibited in vitro by Cd in a dose-dependent manner. Notably, the Cd-induced melatonin synthesis was significantly impaired by treatment with either an H2O2 production inhibitor (DPI) or an NO scavenger (cPTIO). The combination of both inhibitors almost completely abolished Cd-induced melatonin synthesis, suggesting an absolute requirement for H2O2 and NO. However, neither serotonin nor N-acetylserotonin (NAS) was induced by H2O2 alone. In contrast, NO significantly induced serotonin production but not NAS or melatonin production. This indicated that serotonin did not enter chloroplasts, where serotonin N-acetyltransferase (SNAT) is constitutively expressed. This suggests that chloroplastidic SNAT expression prevents increased melatonin production after exposure to stress, ultimately leading to the maintenance of a steady-state melatonin level inside cells.
Melatonin reduces inflammatory response in peripheral T helper lymphocytes from relapsing-remitting multiple sclerosis patients J. Pineal. Res. (IF 10.391) Pub Date : 2017-09-06 Nuria Álvarez-Sánchez, Ivan Cruz-Chamorro, María Díaz-Sánchez, Helia Sarmiento-Soto, Pablo Medrano-Campillo, Alicia Martínez-López, Patricia J. Lardone, Juan M. Guerrero, Antonio Carrillo-Vico
Multiple sclerosis (MS) is a neuroinflammatory disease of the central nervous system in which the immune system plays a central role. In particular, effector populations such as T helper (Th) 1, Th9, Th17, and Th22 cells are involved in disease development, whereas T regulatory cells (Tregs) are associated with the resolution of the disease. Melatonin levels are impaired in patients with MS, and exogenous melatonin ameliorates the disease in MS animal models by modulating the Th1/Th17/Treg responses and also improves quality of life and several symptoms in patients with MS. However, no study has examined melatonin's effect on T cells from relapsing-remitting MS (RR-MS) patients. Therefore, the objectives of the present study were to evaluate the effects of the in vitro administration of melatonin to peripheral blood mononuclear cells (PBMCs) from 64 RR-MS patients and 64 sex- and age-matched healthy subjects on Th1, Th9, Th17, Th22, and Treg responses and to analyze the expression of the melatonin effector/receptor system in these cells. Melatonin decreased Th1 and Th22 responses in patients, whereas it did not affect the Th17 and Treg subsets. Melatonin also promoted skewing toward a more protective cytokine microenvironment, as shown by an increased anti-inflammatory/Th1 ratio. Furthermore, for the first time, we describe the overexpression of the melatonin effector/receptor system in PBMCs from patients with MS; this alteration might be relevant to the disease because acetylserotonin O-methyltransferase expression significantly correlates with disease progression and T effector/regulatory responses in patients. Therefore, our data suggest that melatonin may be an effective treatment for MS.
Melatonin suppresses platelet activation and function against cardiac ischemia/reperfusion injury via PPARγ/FUNDC1/mitophagy pathways J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-21 Hao Zhou, Dandan Li, Pingjun Zhu, Shunying Hu, Nan Hu, Sai Ma, Ying Zhang, Tianwen Han, Jun Ren, Feng Cao, Yundai Chen
Platelet activation is a major (patho-) physiological mechanism that underlies ischemia/reperfusion (I/R) injury. In this study, we explored the molecular signals for platelet hyperactivity and investigated the beneficial effects of melatonin on platelet reactivity in response to I/R injury. After reperfusion, peroxisome proliferator-activated receptor γ (PPARγ) was progressively downregulated in patients with acute myocardial infarction undergoing coronary artery bypass grafting (CABG) surgery and in mice with I/R injury model. Loss of PPARγ was closely associated with FUN14 domain containing 1 (FUNDC1) dephosphorylation and mitophagy activation, leading to increased mitochondrial electron transport chain complex (ETC.) activity, enhanced mitochondrial respiratory function, and elevated ATP production. The improved mitochondrial function strongly contributed to platelet aggregation, spreading, expression of P-selectin, and final formation of micro-thromboses, eventually resulting in myocardial dysfunction and microvascular structural destruction. However, melatonin powerfully suppressed platelet activation via restoration of the PPARγ content in platelets, which subsequently blocked FUNDC1-required mitophagy, mitochondrial energy production, platelet hyperactivity, and cardiac I/R injury. In contrast, genetic ablation of PPARγ in platelet abolished the beneficial effects of melatonin on mitophagy, mitochondrial ATP supply, and platelet activation. Our results lay the foundation for the molecular mechanism of platelet activation in response to I/R injury and highlight that the manipulation of the PPARγ/FUNDC1/mitophagy pathway by melatonin could be a novel strategy for cardioprotection in the setting of cardiac I/R injury.
Melatonin protects against the pathological cardiac hypertrophy induced by transverse aortic constriction through activating PGC-1β: In vivo and in vitro studies J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-16 Mengen Zhai, Zhenhua Liu, Bin Zhang, Lin Jing, Buying Li, Kaifeng Li, Xiuju Chen, Meng Zhang, Bo Yu, Kai Ren, Yang Yang, Wei Yi, Jian Yang, Jincheng Liu, Dinghua Yi, Hongliang Liang, Zhenxiao Jin, Russel J. Reiter, Weixun Duan, Shiqiang Yu
Melatonin, a circadian molecule secreted by the pineal gland, confers a protective role against cardiac hypertrophy induced by hyperthyroidism, chronic hypoxia, and isoproterenol. However, its role against pressure overload-induced cardiac hypertrophy and the underlying mechanisms remains elusive. In this study, we investigated the pharmacological effects of melatonin on pathological cardiac hypertrophy induced by transverse aortic constriction (TAC). Male C57BL/6 mice underwent TAC or sham surgery at day 0 and were then treated with melatonin (20 mg/kg/day, via drinking water) for 4 or 8 weeks. The 8-week survival rate following TAC surgery was significantly increased by melatonin. Melatonin treatment for 8 weeks markedly ameliorated cardiac hypertrophy. Compared with the TAC group, melatonin treatment for both 4 and 8 weeks reduced pulmonary congestion, upregulated the expression level of α-myosin heavy chain, downregulated the expression level of β-myosin heavy chain and atrial natriuretic peptide, and attenuated the degree of cardiac fibrosis. In addition, melatonin treatment slowed the deterioration of cardiac contractile function caused by pressure overload. These effects of melatonin were accompanied by a significant upregulation in the expression of peroxisome proliferator-activated receptor-gamma co-activator-1 beta (PGC-1β) and the inhibition of oxidative stress. In vitro studies showed that melatonin also protects against angiotensin II-induced cardiomyocyte hypertrophy and oxidative stress, which were largely abolished by knocking down the expression of PGC-1β using small interfering RNA. In summary, our results demonstrate that melatonin protects against pathological cardiac hypertrophy induced by pressure overload through activating PGC-1β.
Melatonin inhibits nucleus pulposus (NP) cell proliferation and extracellular matrix (ECM) remodeling via the melatonin membrane receptors mediated PI3K-Akt pathway J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-16 Zheng Li, Xingye Li, Chong Chen, Matthew T. V. Chan, William Ka Kei Wu, Jianxiong Shen
Pinealectomy in vertebrates accelerated intervertebral disk degeneration (IDD). However, the potential mechanisms, particularly melatonin's role, are still to be clarified. In this study, for first time, melatonin membrane receptors of MT1 and MT2 were found to be present in the human intervertebral disk tissues and nucleus pulposus (NP) cells, respectively. Melatonin treatment significantly inhibited NP cell proliferation in dose-dependent manner. Accordingly, melatonin down-regulated gene expression of cyclin D1, PCNA, matrix metallopeptidase-3, and matrix metallopeptidase-9 and upregulated gene expression of collagen type II alpha 1 chain and aggrecan in NP cells. These effects of melatonin were blocked by luzindole, a nonspecific melatonin membrane receptor antagonist. Signaling pathway analysis indicated that in the intervertebral disk tissues and NP cells, melatonin acted on MT1/2 and subsequently reduced phosphorylation of phosphoinositide 3-kinase p85 regulatory subunit, phosphoinositide-dependent kinase-1, and Akt. The results indicate that melatonin is a crucial regulator of NP cell function and plays a vital role in prevention of IDD.
Melatonin impedes Tet1-dependent mGluR5 promoter demethylation to relieve pain J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-16 Ming-Chun Hsieh, Yu-Cheng Ho, Cheng-Yuan Lai, Dylan Chou, Hsueh-Hsiao Wang, Gin-Den Chen, Tzer-Bin Lin, Hsien-Yu Peng
Melatonin (N-acetyl-5-methoxytryptamine)/MT2 receptor-dependent epigenetic modification represents a novel pathway in the treatment of neuropathic pain. Because spinal ten-eleven translocation methylcytosine dioxygenase 1 (Tet1)-dependent epigenetic demethylation has recently been linked to pain hypersensitivity, we hypothesized that melatonin/MT2-dependent analgesia involves spinal Tet1-dependent demethylation. Here, we showed that spinal Tet1 gene transfer by intrathecal delivery of Tet1-encoding vectors to naïve rats produced profound and long-lasting nociceptive hypersensitivity. In addition, enhanced Tet1 expression, Tet1-metabotropic glutamate receptor subtype 5 (mGluR5) promoter coupling, demethylation at the mGluR5 promoter, and mGluR5 expression in dorsal horn neurons were observed. Rats subjected to spinal nerve ligation and intraplantar complete Freund's adjuvant injection displayed tactile allodynia and behavioral hyperalgesia associated with similar changes in the dorsal horn. Notably, intrathecal melatonin injection reversed the protein expression, protein-promoter coupling, promoter demethylation, and pain hypersensitivity induced by Tet1 gene transfer, spinal nerve ligation, and intraplantar complete Freund's adjuvant injection. All the effects caused by melatonin were blocked by pretreatment with a MT2 receptor-selective antagonist. In conclusion, melatonin relieves pain by impeding Tet1-dependent demethylation of mGluR5 in dorsal horn neurons through the MT2 receptor. Our findings link melatonin/MT2 signaling to Tet1-dependent epigenetic demethylation of nociceptive genes for the first time and suggest melatonin as a promising therapy for the treatment of pain.
Rapid modulation of the silent information regulator 1 by melatonin after hypoxia-ischemia in the neonatal rat brain J. Pineal. Res. (IF 10.391) Pub Date : 2017-08-07 Silvia Carloni, Giulia Riparini, Giuseppe Buonocore, Walter Balduini
Increasing evidence indicates that melatonin possesses protective effects toward different kinds of damage in various organs, including the brain. In a neonatal model of hypoxia-ischemia (HI), melatonin was neuroprotective and preserved the expression of the silent information regulator 1 (SIRT1) 24 hours after the insult. This study aimed to gain more insight into the role of SIRT1 in the protective effect of melatonin after HI by studying the early (1 hour) modulation of SIRT1 and its downstream targets, and the consequences on necrosis, apoptosis, autophagy, and glial cell activation. We found that melatonin administered 5 minutes after the ischemic insult significantly reduced necrotic cell death assessed 1 hour after its administration. In parallel, we found a reduced activation of the early phases of intrinsic apoptosis, detected by reduced BAX translocation to the mitochondria and preservation of the mitochondrial expression of cytochrome C, indicating a reduced outer mitochondrial membrane permeabilization in the melatonin-treated ischemic animals. These effects were concomitant to increased expression and activity of SIRT1, reduced expression and acetylation of p53, and increased autophagy activation. Melatonin also reduced HI-induced glial cells activation. SIRT1 was expressed in neurons after HI and melatonin but not in reactive glial cells expressing GFAP. Colocalization between SIRT1 and GFAP was found in some cells in control conditions. In summary, our results provide more insight into the connection between SIRT1 and melatonin in neuroprotection. The possibility that melatonin-induced SIRT1 activity might contribute to differentiate neuronal progenitor cells during the neurodegenerative process needs to be further investigated.
Synergistic effect of melatonin and ghrelin in preventing cisplatin-induced ovarian damage via regulation of FOXO3a phosphorylation and binding to the p27Kip1 promoter in primordial follicles J. Pineal. Res. (IF 10.391) Pub Date : 2017-07-18 Hoon Jang, Younghwa Na, Kwonho Hong, Sangho Lee, Sohyeon Moon, Minha Cho, Miseon Park, Ok-Hee Lee, Eun Mi Chang, Dong Ryul Lee, Jung Jae Ko, Woo Sik Lee, Youngsok Choi
Premature ovarian failure during chemotherapy is a serious problem for young women with cancer. To preserve the fertility of these patients, approaches to prevent chemotherapy-induced ovarian failure are needed. In a previous study, we reported that melatonin treatment prevents the depletion of the dormant follicle pool via repression of the simultaneous activation of dormant primordial follicles by cisplatin. However, melatonin's protective effect was only partial and thus insufficient. In this study, we found that the hormone ghrelin enhances the protective effect of melatonin against cisplatin-induced ovarian failure in mouse model. Co-administration of melatonin and ghrelin more effectively prevented cisplatin-induced follicle disruption. Simultaneous treatment with melatonin and ghrelin almost restored the number of primordial follicles and the corpus luteum in cisplatin-treated ovaries, compared with single administration. We found melatonin and ghrelin receptors on the cell membrane of premature oocytes of primordial follicles. In addition, melatonin and ghrelin co-administration inhibited the cisplatin-induced phosphorylation of PTEN and FOXO3a that induces cytoplasmic translocation of FOXO3a. Inhibition of FOXO3a phosphorylation by melatonin and ghrelin increased the binding affinity of FOXO3a for the p27Kip1 promoter in primordial follicles. Co-administration of melatonin and ghrelin in cisplatin-treated ovaries restored the expression of p27Kip1, which is critical for retention of the dormant status of primordial follicles. In conclusion, these findings suggest that melatonin and ghrelin co-administration is suitable for use as a fertoprotective adjuvant therapy during cisplatin chemotherapy in young female cancer patients.
Melatonin reduces endoplasmic reticulum stress and corneal dystrophy-associated TGFBIp through activation of endoplasmic reticulum-associated protein degradation J. Pineal. Res. (IF 10.391) Pub Date : 2017-07-18 Seung-il Choi, Eunhee Lee, Begum Akuzum, Jang Bin Jeong, Yong-Sun Maeng, Tae-im Kim, Eung Kweon Kim
Endoplasmic reticulum (ER) stress is emerging as a factor for the pathogenesis of granular corneal dystrophy type 2 (GCD2). This study was designed to investigate the molecular mechanisms underlying the protective effects of melatonin on ER stress in GCD2. Our results showed that GCD2 corneal fibroblasts were more susceptible to ER stress-induced death than were wild-type cells. Melatonin significantly inhibited GCD2 corneal cell death, caspase-3 activation, and poly (ADP-ribose) polymerase 1 cleavage caused by the ER stress inducer, tunicamycin. Under ER stress, melatonin significantly suppressed the induction of immunoglobulin heavy-chain-binding protein (BiP) and activation of inositol-requiring enzyme 1α (IRE1α), and their downstream target, alternative splicing of X-box binding protein 1(XBP1). Notably, the reduction in BiP and IRE1α by melatonin was suppressed by the ubiquitin-proteasome inhibitor, MG132, but not by the autophagy inhibitor, bafilomycin A1, indicating involvement of the ER-associated protein degradation (ERAD) system. Melatonin treatment reduced the levels of transforming growth factor-β-induced protein (TGFBIp) significantly, and this reduction was suppressed by MG132. We also found reduced mRNA expression of the ERAD system components HRD1 and SEL1L, and a reduced level of SEL1L protein in GCD2 cells. Interestingly, melatonin treatments enhanced SEL1L levels and suppressed the inhibition of SEL1L N-glycosylation caused by tunicamycin. In conclusion, this study provides new insights into the mechanisms by which melatonin confers its protective actions during ER stress. The results also indicate that melatonin might have potential as a therapeutic agent for ER stress-related diseases including GCD2.
Melatonin protects against maternal obesity-associated oxidative stress and meiotic defects in oocytes via the SIRT3-SOD2-dependent pathway J. Pineal. Res. (IF 10.391) Pub Date : 2017-07-18 Longsen Han, Haichao Wang, Ling Li, Xiaoyan Li, Juan Ge, Russel J. Reiter, Qiang Wang
Maternal obesity in humans is associated with poor outcomes across the reproductive spectrum. Emerging evidence indicates that these defects are likely attributed to factors within the oocyte. Although various molecules and pathways may contribute to impaired oocyte quality, prevention of fertility issues associated with maternal obesity is a challenge. Using mice fed a high-fat diet (HFD) as an obesity model, we document spindle disorganization, chromosome misalignment, and elevated reactive oxygen species (ROS) levels in oocytes from obese mice. Oral administration of melatonin to HFD mice not only reduces ROS generation, but also prevents spindle/chromosome anomalies in oocytes, consequently promoting the developmental potential of early embryos. Consistent with this finding, we find that melatonin supplement during in vitro maturation also markedly attenuates oxidative stress and meiotic defects in HFD oocytes. Finally, by performing morpholino knockdown and acetylation-mimetic mutant overexpression assays, we reveal that melatonin ameliorates maternal obesity-induced defective phenotypes in oocytes through the SIRT3-SOD2-dependent mechanism. In sum, our data uncover the marked beneficial effects of melatonin on oocyte quality from obese females; this opens a new area for optimizing culture system as well as fertility management.
Plant mitochondria synthesize melatonin and enhance the tolerance of plants to drought stress J. Pineal. Res. (IF 10.391) Pub Date : 2017-07-17 Lin Wang, Chao Feng, Xiaodong Zheng, Yan Guo, Fangfang Zhou, Dongqian Shan, Xuan Liu, Jin Kong
Synthesis of melatonin in mitochondria was reported in animals. However, there is no report on whether plant mitochondria also produce melatonin. Herein, we show that plant mitochondria are a major site for melatonin synthesis. In an in vitro study, isolated apple mitochondria had the capacity to generate melatonin. Subcellular localization analysis documented that an apple SNAT isoform, MzSNAT5, was localized in the mitochondria of both Arabidopsis protoplasts and apple callus cells. The kinetic analysis revealed that the recombinant MzSNAT5 protein exhibited high enzymatic activity to catalyze serotonin to N-acetylserotonin with the Km and Vmax of 55 μmol/L and 0.909 pmol/min/mg protein at 35°C, respectively; this pathway functioned over a wide range of temperatures from 5 to 75°C. In an in vivo study, MzSNAT5 was drought inducible. The transgenic Arabidopsis ectopically expressing MzSNAT5 elevated the melatonin level and, hence, enhanced drought tolerance. The mechanistic study indicated that the ectopically expressing MzSNAT5 allows plant mitochondria to increase melatonin synthesis. As a potent free radical scavenger, melatonin reduces the oxidative stress caused by the elevated reactive oxygen species which are generated under drought stress in plants. Our findings provide evidence that engineered melatonin-enriched plants exhibit enhanced oxidative tolerance.
Melatonin delays photoreceptor degeneration in a mouse model of autosomal recessive retinitis pigmentosa J. Pineal. Res. (IF 10.391) Pub Date : 2017-06-20 Xiao-Jian Xu, Shu-Min Wang, Ying Jin, Yun-Tao Hu, Kang Feng, Zhi-Zhong Ma
Retinitis pigmentosa (RP) comprises a group of incurable inherited retinal degenerations. Targeting common processes, instead of mutation-specific treatment, has proven to be an innovative strategy to combat debilitating retinal degeneration. Growing evidence indicates that melatonin possesses a potent activity against neurodegenerative disorders by mitigating cell damage associated with apoptosis and inflammation. Given the pleiotropic role of melatonin in central nervous system, the aim of the present study was to investigate whether melatonin would afford protection against retinal degeneration in autosomal recessive RP (arRP). Rd10, a well-characterized murine model of human arRP, received daily intraperitoneal injection of melatonin (15 mg/kg) between postnatal day (P) 13 and P30. Retinas treated with melatonin or vehicle were harvested for analysis at P30 and P45, respectively. The findings showed that melatonin could dampen the photoreceptors death and delay consequent retinal degeneration. We also observed that melatonin weakened the expression of glial fibrillary acidic protein (GFAP) in Müller cells. Additionally, melatonin could alleviate retinal inflammatory response visualized by IBA1 staining, which was further corroborated by downregulation of inflammation-related genes, such as tumor necrosis factor alpha (Tnf-α), chemokine (C-C motif) ligand 2 (Ccl2), and chemokine (C-X-C motif) ligand 10 (Cxcl10). These data revealed that melatonin could ameliorate retinal degeneration through potentially attenuating apoptosis, reactive gliosis, and microglial activation in rd10 mice. Moreover, these results suggest melatonin as a promising agent improving photoreceptors survival in human RP.
Melatonin protects bone marrow mesenchymal stem cells against iron overload-induced aberrant differentiation and senescence J. Pineal. Res. (IF 10.391) Pub Date : 2017-06-20 Fan Yang, Lei Yang, Yuan Li, Gege Yan, Chao Feng, Tianyi Liu, Rui Gong, Ye Yuan, Ning Wang, Elina Idiiatullina, Timur Bikkuzin, Valentin Pavlov, Yang Li, Chaorun Dong, Dawei Wang, Yang Cao, Zhenbo Han, Lai Zhang, Qi Huang, Fengzhi Ding, Zhengang Bi, Benzhi Cai
Bone marrow mesenchymal stem cells (BMSCs) are an expandable population of stem cells which can differentiate into osteoblasts, chondrocytes and adipocytes. Dysfunction of BMSCs in response to pathological stimuli contributes to bone diseases. Melatonin, a hormone secreted from pineal gland, has been proved to be an important mediator in bone formation and mineralization. The aim of this study was to investigate whether melatonin protected against iron overload-induced dysfunction of BMSCs and its underlying mechanisms. Here, we found that iron overload induced by ferric ammonium citrate (FAC) caused irregularly morphological changes and markedly reduced the viability in BMSCs. Consistently, osteogenic differentiation of BMSCs was significantly inhibited by iron overload, but melatonin treatment rescued osteogenic differentiation of BMSCs. Furthermore, exposure to FAC led to the senescence in BMSCs, which was attenuated by melatonin as well. Meanwhile, melatonin was able to counter the reduction in cell proliferation by iron overload in BMSCs. In addition, protective effects of melatonin on iron overload-induced dysfunction of BMSCs were abolished by its inhibitor luzindole. Also, melatonin protected BMSCs against iron overload-induced ROS accumulation and membrane potential depolarization. Further study uncovered that melatonin inhibited the upregulation of p53, ERK and p38 protein expressions in BMSCs with iron overload. Collectively, melatonin plays a protective role in iron overload-induced osteogenic differentiation dysfunction and senescence through blocking ROS accumulation and p53/ERK/p38 activation.
Melatonin influences the sonic hedgehog signaling pathway in porcine cumulus oocyte complexes J. Pineal. Res. (IF 10.391) Pub Date : 2017-06-09 Sanghoon Lee, Jun-Xue Jin, Anukul Taweechaipaisankul, Geon A. Kim, Curie Ahn, Byeong Chun Lee
Melatonin, which is synthesized in the pineal gland and peripheral reproductive organs, has antioxidant properties and regulates physiological processes. It is well known that melatonin affects in vitro maturation (IVM) of oocytes and embryonic development in many species. However, beneficial effects of melatonin on IVM have been explained mainly by indirect antioxidant effects and little information is available on the underlying mechanism by which melatonin directly acts on porcine cumulus oocyte complexes (COCs). Sonic hedgehog (Shh) signaling is important for follicle development, oocyte maturation, and embryo development, and there may be a relationship between melatonin and Shh signaling. To examine this, we designed three groups: (i) control, (ii) melatonin (10−9 mol/L), and (iii) melatonin with cyclopamine (2 μmol/L; Shh signaling inhibitor). The aim of this study was to investigate the effects of these agents on cumulus expansion, oocyte maturation, embryo development after parthenogenetic activation (PA), gene expression in cumulus cells, oocytes and blastocysts, and protein expression in COCs. Melatonin significantly increased the proportion of COCs exhibiting complete cumulus expansion (degree 4), PA blastocyst formation rates, and total cell numbers, which were inhibited by addition of cyclopamine. Simultaneously, the expression of cumulus expansion-related genes (Ptgs1, Ptgs2, and Has2) and Shh signaling-related genes (Shh, Pthc1, Smo, and Gli1) and proteins (Ptch1, Smo, and Gli1) in cumulus cells was upregulated in the melatonin-treated group, and these effects were also inhibited by cyclopamine. In conclusion, our results suggest that Shh signaling mediates effects of melatonin to improve porcine cumulus expansion and subsequent embryo development.
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