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  • Osteoprotegerin promotes intimal hyperplasia and contributes to in-stent restenosis: Role of an αVβ3/FAK dependent YAP pathway
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2020-01-17
    Yuhu He; Pu Zou; Yufei Lu; Daile Jia; Xuping Li; Hui Yang; Liang Tang; Zhaowei Zhu; Tao Tu; Shi Tai; Yichao Xiao; Mingxian Chen; Lin Lu; Shenghua Zhou
  • Dissection of heterocellular cross-talk in vascularized cardiac tissue mimetics
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-19
    Julian Uwe Gabriel Wagner; Minh Duc Pham; Luka Nicin; Marie Hammer; Katharina Bottermann; Ting Yuan; Rahul Sharma; David John; Marion Muhly-Reinholz; Lukas Tombor; Martin Hardt; Josef Madl; Stefanie Dimmeler; Jaya Krishnan
  • Oxidative stress contributes to vascular calcification in patients with chronic kidney disease
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-19
    Mei Huang; Li Zheng; Hui Xu; Damu Tang; Lizhen Lin; Jin Zhang; Cuifang Li; Wei Wang; Qiongjing Yuan; Lijian Tao; Zunlong Ye

    Vascular calcification (VC) is a major cause of mortality in patients with chronic kidney disease (CKD). While elevations in serum phosphorus contribute to VC, we provide evidence here for a major role of oxidative stress (OS) in VC pathogenesis without an apparent increase in serum phosphorus in early CKD. In a rat model for stage 5 CKD (CKD5), we observed 1) robust increases of VC and OS, 2) significant reductions of smooth muscle 22 alpha (SM22α) and calponin, and 3) upregulations in Runt-related transcription factor 2 (RUNX2) and collagen I in vascular smooth muscle cells (VSMCs). Inhibition of OS using MnTMPyP dramatically reduced these events without normalization of hyperphosphatemia. In CKD5 patients with VC (n = 11) but not in those without VC (n = 13), OS was significantly elevated. While the serum levels of calcium and phosphate were not altered in the animal model for early stage CKD (ECKD), OS, VC, SM22α, calponin, RUNX2, collagen I and NADPH oxidase 1 (NOX1) in VSMCs were all significantly changed. More importantly, serum (5%) derived from patients with ECKD (n = 30) or CKD5 (n = 30) induced SM22α and calponin downregulation, and RUNX2, collagen I, NOX1 upregulation along with a robust elevation of OS and calcium deposition in primary rat VSMCs. These alterations were all reduced by MnTMPyP, ML171 (a NOX1 inhibitor), and U0126 (an inhibitor of Erk signaling). Collectively, we provide a comprehensive set of evidence supporting an important role of OS in promoting VC development in CKD patients (particularly in those with ECKD); this was at least in part through induction of osteoblastic transition in VSMCs which may involve the Erk singling. Our research thus suggests that reductions in OS may prevent VC in CKD patients.

  • Genetic and functional implications of an exonic TRIM55 variant in heart failure
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-19
    Juho Heliste; Himanshu Chheda; Ilkka Paatero; Tiina A. Salminen; Yevhen Akimov; Jere Paavola; Klaus Elenius; Tero Aittokallio
  • Atorvastatin protects cardiomyocyte from doxorubicin toxicity by modulating survivin expression through FOXO1 inhibition
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-19
    Jaewon Oh; Beom Seob Lee; Gibbeum Lim; Heejung Lim; Chan Joo Lee; Sungha Park; Sang-Hak Lee; Ji Hyung Chung; Seok-Min Kang

    Background Survivin has an anti-apoptotic effect against anthracycline-induced cardiotoxicity. Clinically, statin use is associated with a lower risk for heart failure in breast cancer patients with anthracycline chemotherapy. So, the purpose of our study was to investigate whether survivin mediates the protective effect of statin against anthracycline-induced cardiotoxicity. Methods Mice were treated once a week with 5 mg/kg doxorubicin for 4 weeks with or without atorvastatin 20 mg/kg every day then heart tissues were analyzed. Molecular and cellular biology analyses were performed with H9c2 cell lysates. Results Doxorubicin suppressed survivin expression via activation of FOXO1 in H9c2 cardiomyocytes. Whereas, atorvastatin inhibited FOXO1 by increasing phosphorylation and inhibiting nuclear localization. Doxorubicin induced FOXO1 binding to STAT3 and prevented STAT3 from interacting with Sp1. However, atorvastatin inhibited these interactions and stabilized STAT3/Sp1 transcription complex. Chromatin immunoprecipitation analysis demonstrated that doxorubicin decreased STAT3/Sp1 complex binding to survivin promoter, whereas atorvastatin stabilized this binding. In mouse model, atorvastatin rescued doxorubicin-induced reduction of survivin expression and of heart function measured by cardiac magnetic resonance imaging. Conclusions Our study suggested a new pathophysiologic mechanism that survivin mediated protective effect of atorvastatin against doxorubicin-induced cardiotoxicity via FOXO1/STAT3/Sp1 transcriptional network.

  • Progranulin deficiency leads to enhanced age-related cardiac hypertrophy through complement C1q-induced β-catenin activation
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-19
    Yinghong Zhu; Tohru Ohama; Ryota Kawase; Jiuyang Chang; Hiroyasu Inui; Kotaro Kanno; Takeshi Okada; Daisaku Masuda; Masahiro Koseki; Makoto Nishida; Yasushi Sakata; Shizuya Yamashita

    Aims Age-related cardiac hypertrophy and subsequent heart failure are predicted to become increasingly serious problems in aging populations. Progranulin (PGRN) deficiency is known to be associated with accelerated aging in the brain. We aimed to evaluate the effects of PGRN deficiency on cardiac aging, including left ventricular hypertrophy. Methods and results Echocardiography was performed on wild-type (WT) and PGRN-knockout (KO) mice every 3 months from 3 to 18 months of age. Compared to that of WT mice, PGRN KO mice exhibited age-dependent cardiac hypertrophy and cardiac dysfunction at 18 months. Morphological analyses showed that the heart weight to tibia length ratio and cross-sectional area of cardiomyocytes at 18 months were significantly increased in PGRN KO mice relative to those in WT mice. Furthermore, accumulation of lipofuscin and increases in senescence markers were observed in the hearts of PGRN KO mice, suggesting that PGRN deficiency led to enhanced aging of the heart. Enhanced complement C1q (C1q) and activated β-catenin protein expression levels were also observed in the hearts of aged PGRN KO mice. Treatment of PGRN-deficient cardiomyocytes with C1q caused β-catenin activation and cardiac hypertrophy. Blocking C1q-induced β-catenin activation in PGRN-depleted cardiomyocytes attenuated hypertrophic changes. Finally, we showed that C1 inhibitor treatment reduced cardiac hypertrophy and dysfunction in old KO mice, possibly by reducing β-catenin activation. These results suggest that C1q is a crucial regulator of cardiac hypertrophy induced by PGRN ablation. Conclusion The present study demonstrates that PGRN deficiency enhances age-related cardiac hypertrophy via C1q-induced β-catenin activation. PGRN is a potential therapeutic target to prevent cardiac hypertrophy and dysfunction.

  • Crucial role of NLRP3 inflammasome in a murine model of Kawasaki disease
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    Fumiya Anzai, Sachiko Watanabe, Hiroaki Kimura, Ryo Kamata, Tadayoshi Karasawa, Takanori Komada, Jun Nakamura, Noriko Nagi-miura, Naohito Ohno, Yasuchika Takeishi, Masafumi Takahashi
  • Ca2+/calmodulin-dependent protein kinase II is essential in hyperacute pressure overload
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    Maria J. Baier, Susanne Klatt, Karin P. Hammer, Lars S. Maier, Adam G. Rokita

    Background Activation of Ca2+/calmodulin-dependent protein kinase II (CaMKII) is established as a central intracellular trigger for various cardiac pathologies such as hypertrophy, heart failure or arrhythmias in animals and humans suggesting CaMKII as a promising target protein for future medical treatments. However, the physiological role of CaMKII is scarcely well defined. Aim & methods To investigate the role of CaMKII in hyperacute pressure overload, we evaluated the effects of pressure overload induced by transverse aortic constriction (TAC) on survival, cardiac function, protein expression and excitation-contraction coupling (ECC) in female WT littermate vs. AC3-I mice 2 days after TAC (2d post TAC). AC3-I mice express the CaMKII inhibitor autocamtide-3 related inhibitory peptide (AiP) under the control of the α-myosin heavy chain promotor in the heart. Results CaMKII activation is significantly increased in WT TAC vs. sham mice 2d post TAC. Interestingly, survival is significantly reduced in AC3-I animals within the first five days after TAC compared to WT TAC littermates, while systolic cardiac function is markedly reduced in AC3-I TAC vs. AC3-I sham mice, but preserved in WT TAC vs. WT sham mice. Proteins regulating ECC such as ryanodine receptors (RyR2) and phospholamban (PLB) are hypophosphorylated at their CaMKII phosphorylation site in AC3-I TAC mice, but hyperphosphorylated in WT TAC mice compared to controls. In isolated cardiomyocytes fractional shortening is significantly impaired in AC3-I compared to WT mice 2d post TAC, and CaMKII incubation with AiP mimics the AC3-I phenotype in cardiomyocytes from WT TAC mice in vitro. In summary, this suggests cardiac dysfunction due to CaMKII inhibition as a potential cause of increased mortality in AC3-I TAC mice. However, proarrhythmic spontaneous Ca2+ release events (SCR) appear less frequent in cardiomyocytes from AC3-I TAC mice than in WT TAC mice. Conclusions Our data indicate that excessive CaMKII inhibition as present in AC3-I transgenic mice leads to an impaired adaptation of ECC to hyperacute pressure overload resulting in diminished cardiac contractility and increased death. Thus, our data suggest that in pressure overload the activation of CaMKII is a pivotal, but previously unknown part of hyperacute stress physiology in the heart, while CaMKII inhibition, albeit potentially antiarrhythmic, can be detrimental. This should be taken into account for future studies with CaMKII inhibitors as therapeutic agents.

  • Inhibition of DRG-TRPV1 upregulation in myocardial ischemia contributes to exogenous cardioprotection
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    ShijinXu, Yan Xu, Xueying Cheng, Cheng Huang, Yonglu Pan, Shiyun Jin, Wei Xiong, Li Zhang, Shufang He, Ye Zhang

    Myocardium ischemia-reperfusion injury (IRI) is the major cause of postoperative cardiac dysfunction. While intrathecal morphine preconditioning (ITMP) can reduce IRI in animals, the molecular processes underlying IRI and ITMP remain elusive. Transient receptor potential vanilloid type 1 (TRPV1)is highly expressed in cardiac sensory neurons and has a crucial role in detecting myocardial ischemia. This study aimed to determine the role of up-regulated dorsal root ganglion (DRG)-TRPV1 in IRI and whether its inhibition contributes to ITMP-induced cardioprotection. Animal model of IRI was established by left coronary artery occlusion (30 min) and reperfusion (2 h) in rats. Intrathecal intubation was prepared for morphine preconditioning, TRPV1-shRNA or selective TRPV1 antagonist administration. After IRI, both protein and phosphorylation levels of TRPV1 were significantly increased, and the immunofluorescence intensity of TRPV1 was increased and colocalized with μ-opioid receptors in DRG. Intrathecal pre-administration of either TRPV1-shRNA or TRPV1 antagonist significantly reduced myocardial injury and the upregulation of TRPV1 in DRG induced by IRI. Simultaneously, ITMP significantly suppressed TRPV1 protein expression and phosphorylation in DRG, as well as the heart infarct size and arrhythmia score caused by IRI. The suppression of TRPV1 elevation and activation by ITMP were reversed by intrathecal injection of the selective μ receptor antagonist. Furthermore, IRI elevated DRG cAMP, while intrathecal administration of the selective cAMP-PKA inhibitor reduced myocardial injury. Finally, we showed that activation of opioid receptor by morphine inhibited PKA activator-induced TRPV1 channel activity at the cellular level. These findings suggest that the elevation and activation of TRPV1 in DRG during myocardial ischemia-reperfusion might be responsible for cardiac injury. ITMP exerts cardioprotection by inhibiting DRG-TRPV1 activity via modulation cAMP. Therefore, inhibition of TRPV1 upregulation in DRG might be used as a novel therapeutic mechanism for myocardium ischemia-reperfusion injury.

  • Angiotensin peptide synthesis and cyclic nucleotide modulation in sympathetic stellate ganglia
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    E.N. Bardsley, O.C. Neely, D.J. Paterson

    Chronically elevated angiotensin II is a widely-established contributor to hypertension and heart failure via its action on the kidneys and vasculature. It also augments the activity of peripheral sympathetic nerves through activation of presynaptic angiotensin II receptors, thus contributing to sympathetic over-activity. Although some cells can synthesis angiotensin II locally, it is not known if this machinery is present in neurons closely coupled to the heart. Using a combination of RNA sequencing and quantitative real-time polymerase chain reaction, we demonstrate evidence for a renin-angiotensin synthesis pathway within human and rat sympathetic stellate ganglia, where significant alterations were observed in the spontaneously hypertensive rat stellate ganglia compared with Wistar stellates. We also used Förster Resonance Energy Transfer to demonstrate that administration of angiotensin II and angiotensin 1–7 peptides significantly elevate cyclic guanosine monophosphate in the rat stellate ganglia. Whether the release of angiotensin peptides from the sympathetic stellate ganglia alters neurotransmission and/or exacerbates cardiac dysfunction in states associated with sympathetic over activity remains to be established.

  • In vitro and in vivo cardioprotective and metabolic efficacy of vitamin E TPGS/Apelin
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    Patricia Leme Goto, Mathieu Cinato, Fadi Merachli, Bohdana Vons, Tony Jimenez, Dimitri Marsal, Nika Todua, Halina Loy, Yohan Santin, Stéphanie Cassel, Muriel Blanzat, Helene Tronchere, Christophe Dejugnat, Oksana Kunduzova, Frederic Boal

    Aims Apelin and vitamin E have been proposed as signaling molecules, but their synergistic role is unknown. The aim of this work was to develop vitamin E TPGS/Apelin system to test their cardioprotective and metabolic efficacy in vitro and in vivo. Methods FDA-approved surfactant D-α-tocopheryl polyethylene glycol 1000 succinate (TPGS-1000) and Apelin complex were characterized by physico-chemical methods (CMC determination, dynamic light scattering and circular dichroism). In vitro studies were carried out on H9C2 cardiomyoblasts and isolated murine cardiomyocytes. In vivo studies were performed in isoproterenol- and high-fat diet-induced cardiac remodeling models in mice. Results We found that vitamin E TPGS/Apelin provide cardioprotective and metabolic efficacy in vitro and in vivo. In vitro studies revealed that vitamin E TPGS/Apelin reduces hypoxia-induced mitochondrial ROS production in cultured cardiomyocytes and H9C2 cardiomyoblasts. In addition, vitamin E TPGS/Apelin confers apoptotic response to hypoxic stress in cells. In a mouse model of isoproterenol-induced cardiac injury, TPGS is not able to affect cardiac remodeling, however combination of vitamin E TPGS and Apelin counteracts myocardial apoptosis, oxidative stress, hypertrophy and fibrosis. Furthermore, combination treatment attenuated obesity-induced cardiometabolic and fibrotic remodeling in mice. Conclusion Together, our data demonstrated the therapeutic benefits of vitamin E TPGS/Apelin complex to combat cardiovascular and metabolic disorders.

  • Defining decreased protein succinylation of failing human cardiac myofibrils in ischemic cardiomyopathy
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-10
    Hadi R. Ali, Cole R. Michel, Ying H. Lin, Timothy A. McKinsey, Mark Y. Jeong, Amrut V. Ambardekar, Joseph C. Cleveland, Richard Reisdorph, Nichole Reisdorph, Kathleen C. Woulfe, Kristofer S. Fritz

    Succinylation is a post-translational modification of protein lysine residues with succinyl groups derived from succinyl CoA. Succinylation is considered a significant post-translational modification with the potential to impact protein function which is highly conserved across numerous species. The role of succinylation in the heart, especially in heart failure and myofibril mechanics, remains largely unexplored. Mechanical parameters were measured in myofibrils isolated from failing hearts of ischemic cardiomyopathy patients and non-failing donor controls. We employed mass spectrometry to quantify differential protein expression in myofibrils from failing ischemic cardiomyopathy hearts compared to non-failing hearts. In addition, we combined peptide enrichment by immunoprecipitation with liquid chromatography tandem mass spectrometry to quantitatively analyze succinylated lysine residues in these myofibrils. Several key parameters of sarcomeric mechanical interactions were altered in myofibrils isolated from failing ischemic cardiomyopathy hearts, including lower resting tension and a faster rate of activation. Of the 100 differentially expressed proteins, 46 showed increased expression in ischemic heart failure, while 54 demonstrated decreased expression in ischemic heart failure. Our quantitative succinylome analysis identified a total of 572 unique succinylated lysine sites located on 181 proteins, with 307 significantly changed succinylation events. We found that 297 succinyl-Lys demonstrated decreased succinylation on 104 proteins, while 10 residues demonstrated increased succinylation on 4 proteins. Investigating succinyl CoA generation, enzyme activity assays demonstrated that α-ketoglutarate dehydrogenase and succinate dehydrogenase activities were significantly decreased in ischemic heart failure. An activity assay for succinyl CoA synthetase demonstrated a significant increase in ischemic heart failure. Taken together, our findings support the hypothesis that succinyl CoA production is decreased and succinyl CoA turnover is increased in ischemic heart failure, potentially resulting in an overall decrease in the mitochondrial succinyl CoA pool, which may contribute to decreased myofibril protein succinylation in heart failure.

  • Leukocyte profiles across the cardiovascular disease continuum a population-based cohort study
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-12-06
    Hilde E. Groot, Irene V. van Blokland, Erik Lipsic, Jacco C. Karper, Pim van der Harst

    Introduction Inflammation plays a pivotal role across all stadia of the cardiovascular disease (CVD) continuum, i.e. non-obstructive coronary artery disease (CAD), myocardial infarction (MI), and ischemic heart failure (iHF). However, inflammation across CVD continuum has not been studied yet within one population. Therefore, we mapped leukocyte profiles across the continuum within the UK Biobank. Methods The UK Biobank cohort study includes >500,000 participants aged 40 to 70 years who were recruited from 22 assessment centers across the United Kingdom from 2006 to 2010. A total of 333,218 individuals with available laboratory measurements at baseline were included in this study. These consisted of controls and individuals who had progression of CVD during follow-up (i.e. who developed CAD, MI, or iHF during follow-up). We investigated whether leukocytes and subtypes of leukocytes at baseline differed among the CVD continuum. Furthermore, we studied the possible interactions between sex and CVD on leukocytes. Results Of 333,218 individuals, 325,054 (97.5%) individuals were categorized as controls, and 8164 (2.5%) individuals had progression of CVD during follow-up. Of those 8164 individuals, 4552 (1.4%) developed CAD during follow-up, 2839 (0.9%) MI, and 773 (0.2%) in iHF. Compared to controls, mean leukocyte levels at baseline increased across the CVD continuum from 6.8·109 cells/L (SD 1.7·109 cells/L) to 7.7·109 cells/L (SD 1.9·109 cells/L) (Ptrend = 2.19·10−132) in individuals who developed iHF. This increase mainly depended on an increase in neutrophils. Furthermore, controls with leukocyte levels in the highest quartile at baseline had a 1.44 higher chance of being diagnosed with CAD during follow-up compared with individuals with leukocyte levels in lower quartiles (OR 1.44, 95% CI 1.34–1.56 P = 9.63·10−21). A similar increased change was observed for neutrophils, lymphocytes, monocytes, and eosinophils. There was a significant interaction between sex and CVD continuum on lymphocytes (P = 8.49·10−5). Conclusion Overall leukocyte count increased across the CVD continuum, which mainly depended on the increase in neutrophil count. High leukocytes in individuals not having CAD at baseline were predictive for the development of CAD during follow-up. Women had a greater increase of lymphocytes across the CVD continuum compared to men. Understanding which cells are key players in which stadium, could serve as a starting point for the identification of new potential therapeutic targets in CVD.

  • PKCβII specifically regulates KCNQ1/KCNE1 channel membrane localization
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-27
    Chen Braun, Xiaorong Xu Parks, Haani Qudsi, Coeli M. Lopes

    The slow voltage-gated potassium channel (IKs) is composed of the KCNQ1 and KCNE1 subunits and is one of the major repolarizing currents in the heart. Activation of protein kinase C (PKC) has been linked to cardiac arrhythmias. Although PKC has been shown to be a regulator of a number of cardiac channels, including IKs, little is known about regulation of the channel by specific isoforms of PKC. Here we studied the role of different PKC isoforms on IKs channel membrane localization and function. Our studies focused on PKC isoforms that translocate to the plasma membrane in response to Gq-coupled receptor (GqPCR) stimulation: PKCα, PKCβI, PKCβII and PKCε. Prolonged stimulation of GqPCRs has been shown to decrease IKs membrane expression, but the specific role of each PKC isoform is unclear. Here we show that stimulation of calcium-dependent isoforms of PKC (cPKC) but not PKCε mimic receptor activation. In addition, we show that general PKCβ (LY-333531) and PKCβII inhibitors but not PKCα or PKCβI inhibitors blocked the effect of cPKC on the KCNQ1/KCNE1 channel. PKCβ inhibitors also blocked GqPCR-mediated decrease in channel membrane expression in cardiomyocytes. Direct activation of PKCβII using constitutively active PKCβII construct mimicked agonist-induced decrease in membrane expression and channel function, while dominant negative PKCβII showed no effect. This suggests that the KCNQ1/KCNE1 channel was not regulated by basal levels of PKCβII activity. Our results indicate that PKCβII is a specific regulator of IKs membrane localization. PKCβII expression and activation are strongly increased in many disease states, including heart disease and diabetes. Thus, our results suggest that PKCβII inhibition may protect against acquired QT prolongation associated with heart disease.

  • Plasma signature of apoptotic microvesicles is associated with endothelial dysfunction and plaque rupture in acute coronary syndromes
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-27
    Effimia Zacharia, Alexios S. Antonopoulos, Evangelos Oikonomou, Nikolaos Papageorgiou, Zoi Pallantza, Antigoni Miliou, Vasiliki Chara Mystakidi, Spyridon Simantiris, Anastasios Kriebardis, Nikolaos Orologas, Eftychia Valasiadi, Spyridon Papaioannou, Nikolaos Galiatsatos, Charalambos Antoniades, Dimitris Tousoulis

    Objective Circulating microvesicles (MV) are surrogate biomarkers of atherosclerosis. However, their role in acute coronary syndromes (ACS) has not been fully elucidated yet. We sought to examine the association of circulating apoptotic MVs with ACS pathophysiology. Approach and results One hundred and fifty-three patients (n = 153) were included in the study; 49 patients with ST-elevation myocardial infarction (STEMI), 35 with non-STEMI (NSTEMI), 38 with unstable angina, 15 with stable coronary artery disease and 16 control individuals. Flow cytometry analysis was used to quantify circulating apoptotic/non-apoptotic (phospatidyloserine+/phospatidyloserine−) endothelial cell (EMV), red blood cell (RMV) and platelet (PMV) derived MV. Flow-mediated dilatation (FMD) of the brachial artery was assessed by ultrasound to estimate endothelial function. The inflammatory profile was assessed by serum C-reactive protein (hsCRP) levels. Apoptotic only (but not non-apoptotic) MV were increased in patients with ACS (EMV, P = 2.32 × 10−9; RMV, P = .0019; PMV, P = .01). Hierarchical clustering of the total population of ACS patients (n = 122) by circulating levels of phospatidyloserine+ EMV, RMV and PMV identified two discreet clusters of patients without any differences in traditional risk factors, but significant differences in brachial FMD (5.2% (2.5) vs. 4.1% (2.3), P < .05) that remained significant after adjustment for co-variates. The prevalence of STEMI, a surrogate for plaque rupture and vessel thrombotic occlusion, was significantly higher in the patient cluster with impaired endothelial function (60% vs 32%, P = .016, adjusted odds ratio for STEMI, 3.041, 95%CI, 1.160 to 7.968, p = .024). Conclusion Our findings indicate that the circulating levels of apoptotic MV are increased in ACS patients and their plasma profiles associate with endothelial dysfunction and thrombotic complications in ACS patients.

  • Multinucleated polyploid cardiomyocytes undergo an enhanced adaptability to hypoxia via mitophagy
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-26
    Yun-Han Jiang, Hai-Long Wang, Jin Peng, Yu Zhu, Hua-Gang Zhang, Fu-Qin Tang, Zhao Jian, Ying-Bin Xiao
  • A-kinase anchoring protein 1 (AKAP1) and its role in some cardiovascular diseases
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-26
    Wenwen Marin

    A-kinase anchoring proteins (AKAPs) play crucial roles in regulating compartmentalized multi-protein signaling networks related to PKA-mediated phosphorylation. The mitochondrial AKAP - AKAP1 proteins are enriched in heart and play cardiac protective roles. This review aims to thoroughly summarize AKAP1 variants from their sequence features to the structure-function relationships between AKAP1 and its binding partners, as well as the molecular mechanisms of AKAP1 in cardiac hypertrophy, hypoxia-induced myocardial infarction and endothelial cells dysfunction, suggesting AKAP1 as a candidate for cardiovascular therapy.

  • Cellular cross-talks in the diseased and aging heart
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-26
    Julian U.G. Wagner, Stefanie Dimmeler

    Communication between cells is an important, evolutionarily conserved mechanism which enables the coordinated function of multicellular organisms. Heterogeneity within cell populations drive a remarkable network of cellular cross-talk that allows the heart to function as an integrated unit with distinct tasks allocated to sub-specialized cells. During diseases and aging, cells acquire an overt disordered state that significantly contributes to an altered cellular cross-talk and hence drive cardiac remodeling processes and cardiovascular diseases. However, adaptive mechanisms, and phenotypic changes in subpopulations of cells (e.g. reparative macrophages or fibroblasts) can also contribute to repair and regeneration. In this article, we review the cellular cross-talks between immune cells, endothelial cells, fibroblasts and cardiomyocytes that control heart failure by contributing to cardiac dysfunction and aging, or by mediating repair and regeneration of the heart after injury.

  • 更新日期:2019-11-21
  • The role of endothelial miRNAs in myocardial biology and disease
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-20
    Jente R.A. Boen, Andreas B. Gevaert, Gilles W. De Keulenaer, Emeline M. Van Craenenbroeck, Vincent F.M. Segers

    The myocardium is a highly structured pluricellular tissue which is governed by an intricate network of intercellular communication. Endothelial cells are the most abundant cell type in the myocardium and exert crucial roles in both healthy myocardium and during myocardial disease. In the last decade, microRNAs have emerged as new actors in the regulation of cellular function in almost every cell type. Here, we review recent evidence on the regulatory function of different microRNAs expressed in endothelial cells, also called endothelial microRNAs, in healthy and diseased myocardium. Endothelial microRNA emerged as modulators of angiogenesis in the myocardium, they are implicated in the paracrine role of endothelial cells in regulating cardiac contractility and homeostasis, and interfere in the crosstalk between endothelial cells and cardiomyocytes.

  • Potential targets for intervention against doxorubicin-induced cardiotoxicity based on genetic studies: a systematic review of the literature
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-18
    Yan Chen, Tianyang Huang, Wei Shi, Jiansong Fang, Hongkuan Deng, Guozhen Cui

    Cardiotoxicity is a well-known adverse effect of doxorubicin (Dox) administration, but the underlying molecular mechanism of this effect is not fully understood. Over the past two decades, considerable efforts have focused on the potential molecular targets of cardiotoxicity in the hope that novel targeted therapies will be generated to attenuate Dox-induced cardiotoxicity. Here, we provide a comprehensive overview of genetically modified animals that show enhanced or reduced susceptibility to the cardiotoxic effects of Dox. We focused on the process by which the molecules involved in DNA damage, oxidative stress, apoptosis, autophagy and necrosis are affected in the presence of Dox. We also present a protein-protein interaction network and explain the contribution of the components to the process of Dox-induced cardiotoxicity. More importantly, data from the literature have indicated that PI3Kγ and Rac1 are potential targets with therapeutic advantages in cancer therapy; molecules that target these proteins can simultaneously attenuate Dox-induced cardiotoxicity and enhance its anticancer activity. This review highlights the potential molecular targets that are critical regulators involved in Dox-mediated cardiotoxicity, thus providing further insight into the development of potential treatment strategies to prevent the cardiotoxic effects and enhance the anticancer efficiency of Dox in cancer patients.

  • Conversion of human cardiac progenitor cells into cardiac pacemaker-like cells
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-10-31
    Suchi Raghunathan, Jose Francisco Islas, Brandon Mistretta, Dinakar Iyer, Liheng Shi, Preethi H. Gunaratne, Gladys Ko, Robert J. Schwartz, Bradley K. McConnell

    We used a screening strategy to test for reprogramming factors for the conversion of human cardiac progenitor cells (CPCs) into Pacemaker-like cells. Human transcription factors SHOX2, TBX3, TBX5, TBX18, and the channel protein HCN2, were transiently induced as single factors and in trio combinations into CPCs, first transduced with the connexin 30.2 (CX30.2) mCherry reporter. Following screens for reporter CX30.2 mCherry gene activation and FACS enrichment, we observed the definitive expression of many pacemaker specific genes; including, CX30.2, KCNN4, HCN4, HCN3, HCN1, and SCN3b. These findings suggest that the SHOX2, HCN2, and TBX5 (SHT5) combination of transcription factors is a much better candidate in driving the CPCs into Pacemaker-like cells than other combinations and single transcription factors. Additionally, single-cell RNA sequencing of SHT5 mCherry+ cells revealed cellular enrichment of pacemaker specific genes including TBX3, KCNN4, CX30.2, and BMP2, as well as pacemaker specific potassium and calcium channels (KCND2, KCNK2, and CACNB1). In addition, similar to human and mouse sinoatrial node (SAN) studies, we also observed the down-regulation of NKX2.5. Patch-clamp recordings of the converted Pacemaker-like cells exhibited HCN currents demonstrated the functional characteristic of pacemaker cells. These studies will facilitate the development of an optimal Pacemaker-like cell-based therapy within failing hearts through the recovery of SAN dysfunction.

  • 更新日期:2019-11-18
  • Viral expression of a SERCA2a-activating PLB mutant improves calcium cycling and synchronicity in dilated cardiomyopathic hiPSC-CMs
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-18
    Daniel R. Stroik, Delaine K. Ceholski, Philip A. Bidwell, Justyna Mleczko, Paul F. Thanel, Forum Kamdar, Joseph M. Autry, Razvan L. Cornea, David D. Thomas

    There is increasing momentum toward the development of gene therapy for heart failure (HF) that is defined by impaired calcium (Ca2+) transport and reduced contractility. We have used FRET (fluorescence resonance energy transfer) between fluorescently-tagged SERCA2a (the cardiac Ca2+ pump) and PLB (phospholamban, ventricular peptide inhibitor of SERCA) to test directly the effectiveness of loss-of-inhibition/gain-of-binding (LOI/GOB) PLB mutants (PLBM) that were engineered to compete with the binding of inhibitory wild-type PLB (PLBWT). Our therapeutic strategy is to relieve PLBWT inhibition of SERCA2a by using the reserve adrenergic capacity mediated by PLB to enhance cardiac contractility. Using a FRET assay, we determined that the combination of a LOI PLB mutation (L31A) and a GOB PLB mutation (I40A) results in a novel engineered LOI/GOB PLBM (L31A/I40A) that effectively competes with PLBWT binding to cardiac SERCA2a in HEK293-6E cells. We demonstrated that co-expression of PLBM enhances SERCA Ca-ATPase activity by increasing enzyme Ca2+ affinity (1/KCa) in PLBWT-inhibited HEK cell homogenates. For an initial assessment of PLBM physiological effectiveness, we used human induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs) from a healthy individual. In this system, we observed that adeno-associated virus 2 (rAAV2)-driven expression of PLBM enhances the amplitude of SR Ca2+ release and the rate of SR Ca2+ re-uptake. To assess therapeutic potential, we used a hiPSC-CM model of dilated cardiomyopathy (DCM) containing PLB mutation R14del, where we observed that rAAV2-driven expression of PLBM rescues arrhythmic Ca2+ transients and alleviates decreased Ca2+ transport. Thus, we propose that PLBM transgene expression is a promising gene therapy strategy that directly targets the underlying pathophysiology of abnormal Ca2+ transport and thus contractility in underlying systolic heart failure.

  • Mitochondrial thioredoxin-2 maintains HCN4 expression and prevents oxidative stress-mediated sick sinus syndrome
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-18
    Bicheng Yang, Yanrui Huang, Haifeng Zhang, Yan Huang, Huanjiao Jenny Zhou, Lawrence Young, Haipeng Xiao, Wang Min
  • The involvement of post-translational modifications in cardiovascular pathologies: Focus on SUMOylation, neddylation, succinylation, and prenylation
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-18
    Jinning Gao, Kai Shao, Xiatian Chen, Zhe Li, Ziqian Liu, Zhongjie Yu, Lynn Htet Htet Aung, Yin Wang, Peifeng Li

    Cardiovascular disease (CVD) is one of the most threatening diseases to human health and life, and the number of patients is increasing year by year. Thus, it is of great significance to study the pathogenesis, prevention and treatment of CVDs. The occurrence and development of CVDs involve dynamic, complex and delicate intracellular processes and the pathogenesis is not entirely clear. In contrast to genetic mutations, most of the protein post-translational modifications (PTMs) are reversible, and can affect the activity, stability, subcellular localization, protein-protein interaction etc., of the substrate targets, emerging as key mediators of a number of CVD progression. Under pathological conditions, the PTMs undergo aberrant balances which cause changes of the substrate target proteins in expression level, localization and capacity to activate downstream signaling pathways. Therefore, new approaches can be created aiming to correct the abnormal PTM alterations in treating CVDs. This review summarizes some of the more recent advances in PTMs, focusing on SUMOylation, neddylation, succinylation, and prenylation, and the effect of these modifications on cardiovascular function and progression, which may provide potential targets for future therapeutics.

  • Homocysteine accelerates atherosclerosis by inhibiting scavenger receptor class B member1 via DNMT3b/SP1 pathway
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-14
    Wei Guo, Huiping Zhang, Anning Yang, Pengjun Ma, Lei Sun, Mei Deng, Caiyan Mao, Jiantuan Xiong, Jianmin Sun, Nan Wang, Shengchao Ma, Lihong Nie, Yideng Jiang

    Homocysteine (Hcy) is an independent risk factor for atherosclerosis, which is characterized by lipid accumulation in the atherosclerotic plaque. Increasing evidence supports that as the main receptor of high-density lipoprotein, scavenger receptor class B member 1 (SCARB1) is protective against atherosclerosis. However, the underlying mechanism regarding it in Hcy-mediated atherosclerosis remains unclear. Here, we found the remarkable inhibition of SCARB1 expression in atherosclerotic plaque and Hcy-treated foam cells, whereas overexpression of SCARB1 can suppress lipid accumulation in foam cells following Hcy treatment. Analysis of SCARB1 promoter showed that no significant change of methylation level was observed both in vivo and in vitro under Hcy treatment. Moreover, it was found that the negative regulation of DNMT3b on SCARB1 was due to the decreased recruitment of SP1 to SCARB1 promoter. Thus, we concluded that inhibition of SCARB1 expression induced by DNMT3b at least partly accelerated Hcy-mediated atherosclerosis through promoting lipid accumulation in foam cells, which was attributed to the decreased binding of SP1 to SCARB1 promoter. In our point, these findings will provide novel insight into an epigenetic mechanism for atherosclerosis.

  • Programmed death-ligand 1 triggers PASMCs pyroptosis and pulmonary vascular fibrosis in pulmonary hypertension
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2019-11-14
    Min Zhang, Wei Xin, Yang Yu, Xinying Yang, Cui Ma, Hongyue Zhang, Ying Liu, Xijuan Zhao, Xue Guan, Xiaoying Wang, Daling Zhu

    Pyroptosis is a pro-inflammatory form of programmed cell death, whose genesis directly depended on caspase-1 activation. Pulmonary hypertension (PH) is a disease characterized, in part, by vascular fibrosis. Up to now, there is no report on the relationship between pyroptosis and vascular fibrosis in PH. Here, we confirmed that pyroptosis had occurred in the media of pulmonary arteries in two PH rat models and hypoxic human pulmonary arterial smooth muscle cells (hPASMCs). Caspase-1 inhibition attenuated the pathogenesis of PH, as assessed by vascular remodeling, right ventricular systolic pressure, right ventricle hypertrophy and hemodynamic parameters of pulmonary vasculature. Moreover, caspase-1 inhibition suppressed pulmonary vascular fibrosis as demonstrated by Masson staining, as well as immunohistochemistry and Western blot analysis of fibrillar collagen. In addition, Programmed death-ligand 1 (PD-L1) was markedly increased in PH, which was regulated by the transcription factor STAT1. Furthermore, PD-L1 knockdown in hPASMCs repressed the onset of hypoxia-induced pyroptosis and fibrosis. Overall, these data identify a critical STAT1-dependent posttranscriptional modification that promotes PD-L1 expression in the pyroptosis of PASMCs to modulate pulmonary vascular fibrosis and accelerate the progression of PH.

  • Stimulus specific changes of energy metabolism in hypertrophied heart.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2009-05-20
    S Rimbaud,H Sanchez,A Garnier,D Fortin,X Bigard,V Veksler,R Ventura-Clapier

    Cardiac energy metabolism is a determinant of the response to hypertrophic stimuli. To investigate how it responds to physiological or pathological stimuli, we compared the energetic status in models of hypertrophy induced by physiological stimuli (pregnancy or treadmill running) and by pathological stimulus (spontaneously hypertensive rats, SHR) in 15 week-old female rats, leading to a 10% cardiac hypertrophy. Late stage of compensated hypertrophy was also studied in 25 week-old SHR (35% of hypertrophy). Markers of cardiac remodelling did not follow a unique pattern of expression: in trained rats, only ANF was increased; in gravid rats, calcineurin activation and BNP expression were reduced while beta-MHC expression was enhanced; all markers were clearly up-regulated in 25 week-old SHR. Respiration of permeabilized fibers revealed a 17% increase in oxidative capacity in trained rats only. Mitochondrial enzyme activities, expression of the master regulator PGC-1alpha and mitochondrial transcription factor A, and content of mitochondrial DNA were not consistently changed, suggesting that compensated hypertrophy does not involve alterations of mitochondrial biogenesis. Mitochondrial fatty acid utilization tended to increase in trained rats and decreased by 14% in 15 week-old SHR. Expression of markers of lipid oxidation, PPARalpha and its down-stream targets MCAD and CPTI, was up-regulated after training and tended to decrease in gravid and 15 week-old SHR rats. Taken together these results show that there is no univocal pattern of cardiac adaptation in response to physiological or pathological hypertrophic stimuli, suggesting that other factors could play a role in determining adaptation of energy metabolism to increased workload.

  • CRNK gene transfer improves function and reverses the myosin heavy chain isoenzyme switch during post-myocardial infarction left ventricular remodeling.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2008-05-23
    Davin L Hart,Maria C Heidkamp,Rekha Iyengar,Kalpana Vijayan,Erika L Szotek,John A Barakat,Marysa Leya,Marcus Henze,Karie Scrogin,Kyle K Henderson,Allen M Samarel

    PYK2 is a Ca(2+)-dependent, nonreceptor protein tyrosine kinase that is involved in the induction of left ventricular hypertrophy (LVH) and its transition to heart failure. We and others have previously investigated PYK2's function in vitro using cultured neonatal and adult rat ventricular myocytes as model systems. However, the function of PYK2 in the in vivo adult heart remains unclear. Here we evaluate the effect of PYK2 inhibition following myocardial infarction (MI) using adenoviral (Adv) overexpression of the C-terminal domain of PYK2, known as CRNK. First we demonstrate that CRNK functions as a dominant-negative inhibitor of PYK2-dependent signaling, presumably by displacing PYK2 from focal adhesions and costameres. Then, male Sprague-Dawley rats (~300 g) underwent permanent left anterior descending coronary artery ligation. One wk post-MI, either Adv-GFP (n=34) or Adv-CRNK (n=28) was administered (10(10) pfu, 0.1 ml) via catheter-based, Optison-mediated gene transfer. LV structure and function were evaluated by echocardiography 1 and 3 wk after gene transfer, and LV tissue was analyzed by real-time RT-PCR and Western blotting. CRNK overexpression was readily detected by Western blotting 1 wk following gene transfer. Adv-CRNK improved overall survival (P=0.03; Logrank Test) and LV fractional shortening (23+/-2% vs. 31+/-2% for Adv-GFP vs. Adv-CRNK infected animals, respectively; P<0.05). Whereas MI hearts exhibited increased beta-, and decreased alpha-myosin heavy chain (MHC) mRNA expression characteristic of LVH, Adv-CRNK reversed the MHC isoenzyme switch (3.3+/-1.4 fold increase in alpha MHC; 0.4+/-0.1 fold decrease in beta MHC; P<0.05 for both). In summary, CRNK gene transfer improves survival, increases LV function, and alters MHC gene expression suggesting an attenuation of LV remodeling post-MI.

  • TGF-beta1 induces cardiac hypertrophic responses via PKC-dependent ATF-2 activation.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2005-08-30
    Joong-Yeon Lim,Sung Joon Park,Ha-Young Hwang,Eun Jung Park,Jae Hwan Nam,Joon Kim,Sang Ick Park

    Several reports have suggested that the TAK1-MKK3/6-p38MAPK signaling axis is important for TGF-beta-related cardiac hypertrophy. Despite this, the effects of exogenous TGF-beta on cardiac hypertrophy and associated signaling mechanisms have not been demonstrated directly. Moreover, the roles of the signaling mechanisms involved in cardiac hypertrophy (TAK1 upstream and p38MAPK downstream) remain unclear. In this study, we investigated the potential involvement of protein kinase C and activating transcription factor-2 in TGF-beta1-induced cardiac hypertrophic responses in cultured neonatal rat ventricular cardiomyocytes. TGF-beta1 treatment resulted in upregulation of mRNA expression or promoter activities of beta-myosin heavy chain, atrial natriuretic factor, and brain natriuretic peptide, and increased myocyte protein content, cell size, and sarcomeric organization. These are all characteristic hallmarks of cardiac hypertrophy. PKC was found to be involved throughout the signaling system, and it was shown that it acts by mediating upstream TAK1 activation and leads to ATF-2 activation. PKC-dependent ATF-2 activation was shown to be involved in TGF-beta1-induced cardiac hypertrophic responses. The PKC inhibitors, GO6976 and GF109203X, completely blocked TGF-beta1-induced TAK1 kinase activity and subsequent downstream signaling pathways including ATF-2 phosphorylation, leading to suppression of ATF-2 transcriptional activity. This inhibitory effect was reflected in cardiac hypertrophic responses such as inhibitions of beta-MHC gene induction and ANF promoter activity. Our results suggest that PKC is involved in TGF-beta1-induced cardiac hypertrophic responses in our cell culture system and that ATF-2 activation plays a role.

  • Non-nuclear estrogen receptor alpha activation in endothelium reduces cardiac ischemia-reperfusion injury in mice.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2017-05-02
    Sara Menazza,Junhui Sun,Swathi Appachi,Ken L Chambliss,Sung Hoon Kim,Angel Aponte,Sohaib Khan,John A Katzenellenbogen,Benita S Katzenellenbogen,Philip W Shaul,Elizabeth Murphy

    Steroid hormone receptors including estrogen receptors (ER) classically function as ligand-regulated transcription factors. However, estrogens also elicit cellular effects through binding to extra-nuclear ER (ERα, ERβ, and G protein-coupled ER or GPER) that are coupled to kinases. How extra-nuclear ER actions impact cardiac ischemia-reperfusion (I/R) injury is unknown. We treated ovariectomized wild-type female mice with estradiol or an estrogen-dendrimer conjugate (EDC), which selectively activates extra-nuclear ER, or vehicle interventions for two weeks. I/R injury was then evaluated in isolated Langendorff perfused hearts. Two weeks of treatment with estradiol significantly decreased infarct size and improved post-ischemic contractile function. Similarly, EDC treatment significantly decreased infarct size and increased post-ischemic functional recovery compared to vehicle-treated hearts. EDC also caused an increase in myocardial protein S-nitrosylation, consistent with previous studies showing a role for this post-translational modification in cardioprotection. In further support of a role for S-nitrosylation, inhibition of nitric oxide synthase, but not soluble guanylyl cyclase blocked the EDC mediated protection. The administration of ICI182,780, which is an agonist of G-protein coupled estrogen receptor (GPER) and an antagonist of ERα and ERβ, did not result in protection; however, ICI182,780 significantly blocked EDC-mediated cardioprotection, indicating participation of ERα and/or ERβ. In studies determining the specific ER subtype and cellular target involved, EDC decreased infarct size and improved functional recovery in mice lacking ERα in cardiomyocytes. In contrast, protection was lost in mice deficient in endothelial cell ERα. Thus, extra-nuclear ERα activation in endothelium reduces cardiac I/R injury in mice, and this likely entails increased protein S-nitrosylation. Since EDC does not stimulate uterine growth, in the clinical setting EDC-like compounds may provide myocardial protection without undesired uterotrophic and cancer-promoting effects.

  • Calreticulin secures calcium-dependent nuclear pore competency required for cardiogenesis.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2016-01-31
    Randolph S Faustino,Atta Behfar,Jody Groenendyk,Saranya P Wyles,Nicolas Niederlander,Santiago Reyes,Michel Puceat,Marek Michalak,Andre Terzic,Carmen Perez-Terzic

    Calreticulin deficiency causes myocardial developmental defects that culminate in an embryonic lethal phenotype. Recent studies have linked loss of this calcium binding chaperone to failure in myofibrillogenesis through an as yet undefined mechanism. The purpose of the present study was to identify cellular processes corrupted by calreticulin deficiency that precipitate dysregulation of cardiac myofibrillogenesis related to acquisition of cardiac phenotype. In an embryonic stem cell knockout model, calreticulin deficit (crt(-/-)) compromised nucleocytoplasmic transport of nuclear localization signal-dependent and independent pathways, disrupting nuclear import of the cardiac transcription factor MEF2C. The expression of nucleoporins and associated nuclear transport proteins in derived crt(-/-) cardiomyocytes revealed an abnormal nuclear pore complex (NPC) configuration. Altered protein content in crt(-/-) cells resulted in remodeled NPC architecture that caused decreased pore diameter and diminished probability of central channel occupancy versus wild type counterparts. Ionophore treatment of impaired calcium handling in crt(-/-) cells corrected nuclear pore microarchitecture and rescued nuclear import resulting in normalized myofibrillogenesis. Thus, calreticulin deficiency alters nuclear pore function and structure, impeding myofibrillogenesis in nascent cardiomyocytes through a calcium dependent mechanism. This essential role of calreticulin in nucleocytoplasmic communication competency ties its regulatory action with proficiency of cardiac myofibrillogenesis essential for proper cardiac development.

  • Subcellular localization of Na/K-ATPase isoforms in ventricular myocytes.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2017-06-08
    Garrick K Yuen,Samuel Galice,Donald M Bers

    The sodium/potassium ATPase (NKA) is essential for establishing the normal intracellular [Na+] and [K+] and transmembrane gradients that are essential for many cellular functions, including cardiac electrophysiology and contractility. Different NKA isoforms exhibit differential expression levels, cellular localization, and function in different tissues and species. Prior work has indicated that the NKA-α1 isoform is quantitatively predominant in cardiac myocytes, but that the α2 isoform is preferentially concentrated in the transverse tubules (TT), possibly at junctions with the sarcoplasmic reticulum (SR) where α2 may preferentially modulate cardiac contractility. Here we measured subcellular localization of NKA-α1 and α2 using super-resolution microscopy (STED and STORM) and isoform-selective antibodies in mouse ventricular myocytes. We confirm the preferential localization of NKA-α2 in TT vs. surface sarcolemma, but also show that α2 is relatively excluded from longitudinal TT elements. In contrast NKA-α1 is relatively uniformly expressed in all three sarcolemmal regions. We also tested the hypothesis that NKA-α2 (vs. α1) is preferentially concentrated at SR junctional sites near ryanodine receptors (RyR2). The results refute this hypothesis, in that NKA-α1 and α2 were equally close to RyR2 at the TT, with no preferential NKA isoform localization near RyR2. We conclude that in contrast to relatively uniform NKA-α1 distribution, NKA-α2 is preferentially concentrated in the truly transverse (and not longitudinal) TT elements. However, NKA-α2 does not preferentially cluster at RyR2 junctions, so the TT NKA-α2 concentration may suffice for preferential effects of NKA-α2 inhibition on cardiac contractility.

  • β-Adrenergic induced SR Ca2+ leak is mediated by an Epac-NOS pathway.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2017-05-10
    Laëtitia Pereira,Dan J Bare,Samuel Galice,Thomas R Shannon,Donald M Bers

    Cardiac β-adrenergic receptors (β-AR) and Ca2+-Calmodulin dependent protein kinase (CaMKII) regulate both physiological and pathophysiological Ca2+ signaling. Elevated diastolic Ca2+ leak from the sarcoplasmic reticulum (SR) contributes to contractile dysfunction in heart failure and to arrhythmogenesis. β-AR activation is known to increase SR Ca2+ leak via CaMKII-dependent phosphorylation of the ryanodine receptor. Two independent and reportedly parallel pathways have been implicated in this β-AR-CaMKII cascade, one involving exchange protein directly activated by cAMP (Epac2) and another involving nitric oxide synthase 1 (NOS1). Here we tested whether Epac and NOS function in a single series pathway to increase β-AR induced and CaMKII-dependent SR Ca2+ leak. Leak was measured as both Ca2+ spark frequency and tetracaine-induced shifts in SR Ca2+, in mouse and rabbit ventricular myocytes. Direct Epac activation by 8-CPT (8-(4-chlorophenylthio)-2'-O-methyl-cAMP) mimicked β-AR-induced SR Ca2+ leak, and both were blocked by NOS inhibition. The same was true for myocyte CaMKII activation (assessed via a FRET-based reporter) and ryanodine receptor phosphorylation. Inhibitor and phosphorylation studies also implicated phosphoinositide 3-kinase (PI3K) and protein kinase B (Akt) downstream of Epac and above NOS activation in this pathway. We conclude that these two independently characterized parallel pathways function mainly via a single series arrangement (β-AR-cAMP-Epac-PI3K-Akt-NOS1-CaMKII) to mediate increased SR Ca2+ leak. Thus, for β-AR activation the cAMP-PKA branch effects inotropy and lusitropy (by effects on Ca2+ current and SR Ca2+-ATPase), this cAMP-Epac-NOS pathway increases pathological diastolic SR Ca2+leak. This pathway distinction may allow novel SR Ca2+ leak therapeutic targeting in treatment of arrhythmias in heart failure that spare the inotropic and lusitropic effects of the PKA branch.

  • Corrigendum to "Chronic β-adrenergic stimulation reverses depressed Ca handling in mice overexpressing inhibitor-2 of protein phosphatase 1" [J Mol Cell Cardiol 125 (2018) 195-204].
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : null
    Uwe Kirchhefer,Elke Hammer,Alexander Heinick,Thomas Herpertz,Gunnar Isensee,Frank U Müller,Joachim Neumann,Jan S Schulte,Kirsten Schulte,Matthias D Seidl,Peter Boknik

  • Expression of multiple KCNE genes in human heart may enable variable modulation of I(Ks).
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2005-02-09
    Andrew L Lundquist,Lauren J Manderfield,Carlos G Vanoye,Christopher S Rogers,Brian S Donahue,Paul A Chang,Davis C Drinkwater,Katherine T Murray,Alfred L George

    Voltage-gated potassium (K(V)) channels are modulated by at least three distinct classes of proteins including the KCNE family of single transmembrane accessory subunits. In the human genome, KCNE proteins are encoded by five genes designated KCNE1 through KCNE5. KCNE1 associates with KCNQ1 in vitro to generate a potassium current closely resembling the slowly activating delayed rectifier (I(Ks)). Other KCNE proteins also affect the activity of heterologously expressed KCNQ1. To investigate the potential physiological relevance of this gene family in human heart, we examined the relative expression of KCNQ1 and all five KCNE genes in samples derived from normal tissues representing major regions of human heart by real-time, quantitative RT-PCR. KCNE genes are expressed in human heart with a relative abundance ranking of KCNE1 > KCNE4 > KCNE5 approximately KCNE3 >> KCNE2. In situ hybridization revealed prominent expression of KCNE1 and KCNE3-5 in human atrial myocytes. In cardiomyopathic hearts, expression of KCNE1, KCNE3, KCNE4, and KCNQ1 was significantly increased, while KCNE2 and KCNE5 exhibited reduced expression. In a cell line stably expressing KCNQ1 and KCNE1, transient expression of KCNE3, KCNE4, or KCNE5 significantly altered I(Ks) current profiles. Even in the presence of additional KCNE1, KCNE4 and KCNE5 exert dominant effects on I(Ks). Although KCNE1 is the predominant KCNE family member expressed in human heart, the abundance of other KCNE transcripts including potential KCNQ1 suppressors (KCNE4 and KCNE5) and their altered expression patterns in disease lead us to speculate that a balance of KCNE accessory subunits may be important for cardiac K(V) channel function.

  • Impaired mitophagy facilitates mitochondrial damage in Danon disease.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2017-05-21
    Sherin I Hashem,Anne N Murphy,Ajit S Divakaruni,Matthew L Klos,Bradley C Nelson,Emily C Gault,Teisha J Rowland,Cynthia N Perry,Yusu Gu,Nancy D Dalton,William H Bradford,Eric J Devaney,Kirk L Peterson,Kenneth L Jones,Matthew R G Taylor,Ju Chen,Neil C Chi,Eric D Adler

    RATIONALE Lysosomal associated membrane protein type-2 (LAMP-2) is a highly conserved, ubiquitous protein that is critical for autophagic flux. Loss of function mutations in the LAMP-2 gene cause Danon disease, a rare X-linked disorder characterized by developmental delay, skeletal muscle weakness, and severe cardiomyopathy. We previously found that human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from Danon patients exhibited significant mitochondrial oxidative stress and apoptosis. Understanding how loss of LAMP-2 expression leads to cardiomyocyte dysfunction and heart failure has important implications for the treatment of Danon disease as well as a variety of other cardiac disorders associated with impaired autophagy. OBJECTIVE Elucidate the pathophysiology of cardiac dysfunction in Danon disease. METHODS AND RESULTS We created hiPSCs from two patients with Danon disease and differentiated those cells into hiPSC-CMs using well-established protocols. Danon hiPSC-CMs demonstrated an accumulation of damaged mitochondria, disrupted mitophagic flux, depressed mitochondrial respiratory capacity, and abnormal gene expression of key mitochondrial pathways. Restoring the expression of LAMP-2B, the most abundant LAMP-2 isoform in the heart, rescued mitophagic flux as well as mitochondrial health and bioenergetics. To confirm our findings in vivo, we evaluated Lamp-2 knockout (KO) mice. Impaired autophagic flux was noted in the Lamp-2 KO mice compared to WT reporter mice, as well as an increased number of abnormal mitochondria, evidence of incomplete mitophagy, and impaired mitochondrial respiration. Physiologically, Lamp-2 KO mice demonstrated early features of contractile dysfunction without overt heart failure, indicating that the metabolic abnormalities associated with Danon disease precede the development of end-stage disease and are not merely part of the secondary changes associated with heart failure. CONCLUSIONS Incomplete mitophagic flux and mitochondrial dysfunction are noted in both in vitro and in vivo models of Danon disease, and proceed overt cardiac contractile dysfunction. This suggests that impaired mitochondrial clearance may be central to the pathogenesis of disease and a potential target for therapeutic intervention.

  • Single-target RNA interference for the blockade of multiple interacting proinflammatory and profibrotic pathways in cardiac fibroblasts.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2013-11-19
    Juliane Tank,Diana Lindner,Xiaomin Wang,Andrea Stroux,Leona Gilke,Martina Gast,Christin Zietsch,Carsten Skurk,Carmen Scheibenbogen,Karin Klingel,Dirk Lassner,Uwe Kühl,Heinz-Peter Schultheiss,Dirk Westermann,Wolfgang Poller

    Therapeutic targets of broad relevance are likely located in pathogenic pathways common to disorders of various etiologies. Screening for targets of this type revealed CCN genes to be consistently upregulated in multiple cardiomyopathies. We developed RNA interference (RNAi) to silence CCN2 and found this single-target approach to block multiple proinflammatory and profibrotic pathways in activated primary cardiac fibroblasts (PCFBs). The RNAi-strategy was developed in murine PCFBs and then investigated in "individual" human PCFBs grown from human endomyocardial biopsies (EMBs). Screening of short hairpin RNA (shRNA) sequences for high silencing efficacy and specificity yielded RNAi adenovectors silencing CCN2 in murine or human PCFBs, respectively. Comparison of RNAi with CCN2-modulating microRNA (miR) vectors expressing miR-30c or miR-133b showed higher efficacy of RNAi. In murine PCFBs, CCN2 silencing resulted in strongly reduced expression of stretch-induced chemokines (Ccl2, Ccl7, Ccl8), matrix metalloproteinases (MMP2, MMP9), extracellular matrix (Col3a1), and a cell-to-cell contact protein (Cx43), suggesting multiple signal pathways to be linked to CCN2. Immune cell chemotaxis towards CCN2-depleted PCFBs was significantly reduced. We demonstrate here that this RNAi strategy is technically applicable to "individual" human PCFBs, too, but that these display individually strikingly different responses to CCN2 depletion. Either genomically encoded factors or stable epigenetic modification may explain different responses between individual PCFBs. The new RNAi approach addresses a key regulator protein induced in cardiomyopathies. Investigation of this and other molecular therapies in individual human PCBFs may help to dissect differential pathogenic processes between otherwise similar disease entities and individuals.

  • Endothelin-1 induces connective tissue growth factor expression in cardiomyocytes.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2008-12-30
    Anna Grazia Recchia,Elisabetta Filice,Daniela Pellegrino,Aldo Dobrina,Maria Carmela Cerra,Marcello Maggiolini

    Endothelin (ET)-1 is a vasoconstrictor involved in cardiovascular diseases. Connective tissue growth factor/CCN2 (CTGF) is a fibrotic mediator overexpressed in human atherosclerotic lesions, myocardial infarction, and hypertension. In different cell types CTGF regulates cell proliferation/apoptosis, migration, and extracellular matrix (ECM) accumulation and plays important roles in angiogenesis, chondrogenesis, osteogenesis, tissue repair, cancer and fibrosis. In the present study, we investigated the ET-1 signaling which triggers CTGF expression in cultured adult mouse atrial-muscle HL-1 cells used as a model system. ET-1 activated the CTGF promoter and induced CTGF expression at both mRNA and protein levels. Real-time PCR analysis revealed CTGF induction also in isolated rat heart preparations perfused with ET-1. Several intracellular signals elicited by ET-1 via ET receptors and even Epidermal Growth Factor Receptor (EGFR) contributed to the up-regulation of CTGF, including ERK activation and induction of the AP-1 components c-fos and c-jun, as also evaluated by ChIP analysis. Moreover, in cells treated with ET-1 the expression of ECM component decorin was abolished by CTGF silencing, indicating that CTGF is involved in ET-1 induced ECM accumulation not only in a direct manner but also through downstream effectors. Collectively, our data indicate that CTGF could be a mediator of the profibrotic effects of ET-1 in cardiomyocytes. CTGF inhibitors should be considered in setting a comprehensive pharmacological approach towards ET-1 induced cardiovascular diseases.

  • Gene expression signals involved in ischemic injury, extracellular matrix composition and fibrosis defined by global mRNA profiling of the human left ventricular myocardium.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2007-03-09
    Anders Gabrielsen,Patrick R Lawler,Wang Yongzhong,Daniel Steinbrüchel,Dimo Blagoja,Gabrielle Paulsson-Berne,Jens Kastrup,Göran K Hansson

    Gene expression signals involved in ischemic injury, extracellular matrix composition and fibrosis defined by global mRNA profiling of the human left ventricular myocardium. The mechanism(s) by which acute and chronic myocardial ischemia translate into the characteristic features of ischemic cardiomyopathy is unresolved at present. We hypothesized that such translation relates to modification of specific gene expression programs during acute and chronic ischemic insults to the myocardium. Global mRNA expression profiles by Affymetrix HG_U133A GeneChip analysis on 33 samples was performed on non-failing human left ventricular myocardium during acute and chronic ischemia in 6 patients undergoing coronary artery by-pass grafting. Results were confirmed by real-time quantitative RT-PCR in 14 patients and supported by histology and immunohistochemistry analyses. Acute ischemia elicited an acute inflammatory response including IL-6, IL-8, MCP-1, VCAM-1 and CYR-61 with an attenuated increase of IL-6 and IL-8 in chronic ischemic myocardium compared to normal myocardium. High mRNA expression of connective tissue growth factor (CTGF) was present in chronic ischemic myocardium with a high degree of correlation between CTGF and mRNA expression of specific genes (e.g. thrombospondin 4, collagen type Ialpha2, versican, adlican, latent transforming growth factor beta binding protein 2 and fibronectin) involved in extracellular matrix remodelling. In conclusion, acute inflammatory induction (e.g. IL-8, IL-6, VCAM-1 and MCP-1) and an acute phase CCN family gene with effects on matrix interactions (CYR-61) might play important roles in the coupling between acute ischemic episodes and chronic myocardial remodelling. In addition, the findings support an important role of CTGF signalling in chronic extracellular matrix remodelling in chronic coronary artery disease.

  • The development of cardiac fibrosis in low tissue factor mice is gender-dependent and is associated with differential regulation of urokinase plasminogen activator.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2007-01-20
    Darren R Davis,Kate Wilson,Melissa J Sam,Sean E Kennedy,Nigel Mackman,John A Charlesworth,Jonathan H Erlich

    Tissue factor (TF) initiates the protease coagulation cascade in response to tissue injury. Homozygous deficiency of murine TF results in embryonic lethality, which is rescued by low-level expression of human TF. These low-TF mice have been shown to develop cardiac fibrosis. We tested the hypothesis that the development of cardiac fibrosis in low-TF mice results from dysregulated protease expression and is affected by gender. Mice were divided into the age groups 2-5, 6-12, 13-18 and 19+ weeks. Fibrosis was assessed by trichrome staining. Protease expression was measured in male and female mice by RT-PCR for mRNA and zymography, ELISA or immunoblot for protein. Urokinase plasminogen activator (uPA) activity was determined by zymography and chromogenic substrate assay. A marked gender effect was noted for the development of fibrosis, with interstitial collagen deposition occurring from 9 weeks in male low-TF mice, but not until 19 weeks in low-TF females. This delayed onset in females was accompanied by delayed up-regulation of molecular markers of injury. Matrix metalloproteinase (MMP)-3 and tissue inhibitor of metalloproteinase (TIMP)-1 expression were up-regulated in the hearts of male low-TF mice from 6 to 12 weeks and in females from 19 weeks. MMP/TIMP dysregulation was not seen prior to cardiac fibrosis and did not appear to explain the gender differences. However, uPA expression and activity were down-regulated prior to cardiac fibrosis in low-TF females, but were up-regulated in age-matched males. This suggests that the down-regulation of uPA in female low-TF mice protects them from more severe cardiac fibrosis.

  • 更新日期:2019-11-01
  • CTGF expression is induced by TGF- beta in cardiac fibroblasts and cardiac myocytes: a potential role in heart fibrosis.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2000-10-03
    M M Chen,A Lam,J A Abraham,G F Schreiner,A H Joly

    Connective tissue growth factor (CTGF) is a cysteine-rich protein induced by transforming growth factor beta (TGF- beta) in connective tissue cells. CTGF can trigger many of the cellular processes underlying fibrosis, such as cell proliferation, adhesion, migration and the synthesis of extracellular matrix; however, its role in acute and chronic cardiac injury is not fully understood. Here, we show that TGF- beta is a specific inducer of CTGF expression in both cardiac fibroblasts and cardiac myocytes. The activity of a CTGF promoter-based reporter construct correlated with endogenous CTGF expression, suggesting that TGF- beta induces CTGF expression most likely by activating its promoter. Upregulation of CTGF coincided with an increase in fibronectin, collagen type I and plasminogen activator inhibitor-1 production. Forskolin, a stimulator of cyclic AMP, blocked TGF- beta induced CTGF expression and reduced the basal level of CTGF, whereas an inhibitor that blocks the MAP kinase signaling pathway (PD 98059) significantly enhanced TGF- beta induced CTGF expression. Furthermore, we found that both TGF- beta and CTGF mRNAs were significantly elevated in the left ventricles and septa of rat hearts 2-16 weeks following myocardial infarction. This correlated well with concomitant increases in fibronectin, and type I and type III collagen mRNA levels in these animal hearts. Significant upregulation of CTGF was also detected in human heart samples derived from patients diagnosed with cardiac ischemia. Based on these findings, we propose that CTGF is an important mediator of TGF- beta signaling in the heart and abnormal expression of this gene could be used as a diagnostic marker for cardiac fibrosis.

  • Adjusted analysis.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2018-05-20
    Paul H Lee

  • Not low hanging but still sweet: Metabolic proteomes in cardiovascular disease.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-11-28
    Emma Monte,Rachel Lopez,Thomas M Vondriska

    The application of proteomics in biology and medicine has reached a moment of truth. The demand of biologists for transformative insights into how cells work, plus the mandate of basic science research to ultimately impact clinical medicine, crystallize as a test on the rigor and reproducibility of any 'omics measurement. Studies like that by Boylston et al. indicate that proteomics can pass that test.

  • Genetic variants associated with risk of atrial fibrillation regulate expression of PITX2, CAV1, MYOZ1, C9orf3 and FANCC.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-06-16
    Ruairidh I R Martin,Mahsa Sheikhali Babaei,Mun-Kit Choy,W Andrew Owens,Timothy J A Chico,Daniel Keenan,Nizar Yonan,Mauro Santibáñez Koref,Bernard D Keavney

    Genome-wide association studies (GWAS) have identified genetic variants in a number of chromosomal regions that are associated with atrial fibrillation (AF). The mechanisms underlying these associations are unknown, but are likely to involve effects of the risk haplotypes on expression of neighbouring genes. To investigate the association between genetic variants at AF-associated loci and expression of nearby candidate genes in human atrial tissue and peripheral blood. Right atrial appendage (RAA) samples were collected from 122 patients undergoing cardiac surgery, of these, 12 patients also had left atrial appendage samples taken. 22 patients had a history of AF. Peripheral blood samples were collected from 405 patients undergoing diagnostic cardiac catheterisation. In order to tag genetic variation at each of nine loci, a total of 367 single nucleotide polymorphisms (SNPs) were genotyped using the Sequenom platform. Total expression of 16 candidate genes in the nine AF-associated regions was measured by quantitative PCR. The relative expression of each allele of the candidate genes was measured on the Sequenom platform using one or more transcribed SNPs to distinguish between alleles in heterozygotes. We tested association between the SNPs of interest and gene expression using total gene expression (integrating cis and trans acting sources of variation), and allelic expression ratios (specific for cis acting influences), in atrial tissue and peripheral blood. We adjusted for multiple comparisons using a Bonferroni approach. In subsidiary analyses, we compared the expression of candidate genes between patients with and without a history of AF. Total expression of 15 transcripts of 14 genes and allelic expression ratio of 14 transcripts of 14 genes in genomic regions associated with AF were measured in right atrial appendage tissue. 8 of these transcripts were also expressed in peripheral blood. Risk alleles at AF-associated SNPs were associated in cis with an increased expression of PITX2a (2.01-fold, p=6.5×10(-4)); and with decreased expression of MYOZ1 (0.39 fold; p=5.5×10(-15)), CAV1 (0.89 fold; p=5.9×10(-8)), C9orf3 (0.91 fold; 1.5×10(-5)), and FANCC (0.94-fold; p=8.9×10(-8)) in right atrial appendage. Of these five genes, only CAV1 was expressed in peripheral blood; association between the same AF risk alleles and lower expression of CAV1 was confirmed (0.91 fold decrease; p=4.2×10(-5)). A history of AF was also associated with a decrease in expression of CAV1 in both right and left atria (0.84 and 0.85 fold, respectively; p=0.03), congruent with the magnitude of the effect of the risk SNP on expression, and independent of genotype. The analyses in peripheral blood showed association between AF risk SNPs and decreased expression of KCNN3 (0.85-fold; p=2.1×10(-4)); and increased expression of SYNE2 (1.12-fold; p=7.5×10(-24)); however, these associations were not detectable in atrial tissue. We identified novel cis-acting associations in atrial tissue between AF risk SNPs and increased expression of PITX2a/b; and decreased expression of CAV1 (an association also seen in peripheral blood), C9orf3 and FANCC. We also confirmed a previously described association between AF risk variants and MYOZ1 expression. Analyses of peripheral blood illustrated tissue-specificity of cardiac eQTLs and highlight the need for larger-scale genome-wide eQTL studies in cardiac tissue. Our results suggest novel aetiological roles for genes in four AF-associated genomic regions.

  • Phosphorylation and function of cardiac myosin binding protein-C in health and disease.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2009-12-08
    David Barefield,Sakthivel Sadayappan

    During the past 5 years there has been an increasing body of literature describing the roles cardiac myosin binding protein C (cMyBP-C) phosphorylation play in regulating cardiac function and heart failure. cMyBP-C is a sarcomeric thick filament protein that interacts with titin, myosin and actin to regulate sarcomeric assembly, structure and function. Elucidating the function of cMyBP-C is clinically important because mutations in this protein have been linked to cardiomyopathy in more than sixty million people worldwide. One function of cMyBP-C is to regulate cross-bridge formation through dynamic phosphorylation by protein kinase A, protein kinase C and Ca(2+)-calmodulin-activated kinase II, suggesting that cMyBP-C phosphorylation serves as a highly coordinated point of contractile regulation. Moreover, dephosphorylation of cMyBP-C, which accelerates its degradation, has been shown to associate with the development of heart failure in mouse models and in humans. Strikingly, cMyBP-C phosphorylation presents a potential target for therapeutic development as protection against ischemic-reperfusion injury, which has been demonstrated in mouse hearts. Also, emerging evidence suggests that cMyBP-C has the potential to be used as a biomarker for diagnosing myocardial infarction. Although many aspects of cMyBP-C phosphorylation and function remain poorly understood, cMyBP-C and its phosphorylation states have significant promise as a target for therapy and for providing a better understanding of the mechanics of heart function during health and disease. In this review we discuss the most recent findings with respect to cMyBP-C phosphorylation and function and determine potential future directions to better understand the functional role of cMyBP-C and phosphorylation in sarcomeric structure, myocardial contractility and cardioprotection.

  • Novel large-particle FACS purification of adult ventricular myocytes reveals accumulation of myosin and actin disproportionate to cell size and proteome in normal post-weaning development.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2017-08-07
    Javier E López,Janhavi Sharma,Jorge Avila,Taylor S Wood,Jonathan E VanDyke,Bridget McLaughlin,Craig K Abbey,Andrew Wong,Bat-Erdene Myagmar,Philip M Swigart,Paul C Simpson,Nipavan Chiamvimonvat

    RATIONALE Quantifying cellular proteins in ventricular myocytes (MCs) is challenging due to tissue heterogeneity and the variety of cell sizes in the heart. In post-weaning cardiac ontogeny, rod-shaped MCs make up the majority of the cardiac mass while remaining a minority of cardiac cells in number. Current biochemical analyses of cardiac proteins do not correlate well the content of MC-specific proteins to cell type or size in normally developing tissue. OBJECTIVE To develop a new large-particle fluorescent-activated cell sorting (LP-FACS) strategy for the purification of adult rod-shaped MCs. This approach is developed to enable growth-scaled measurements per-cell of the MC proteome and sarcomeric proteins (i.e. myosin heavy chain (MyHC) and alpha-actin (α-actin)) content. METHODS AND RESULTS Individual cardiac cells were isolated from 21 to 94days old mice. An LP-FACS jet-in-air system with a 200-μm nozzle was defined for the first time to purify adult MCs. Cell-type specific immunophenotyping and sorting yielded ≥95% purity of adult MCs independently of cell morphology and size. This approach excluded other cell types and tissue contaminants from further analysis. MC proteome, MyHC and α-actin proteins were measured in linear biochemical assays normalized to cell numbers. Using the allometric coefficient α, we scaled the MC-specific rate of protein accumulation to growth post-weaning. MC-specific volumes (α=1.02) and global protein accumulation (α=0.94) were proportional (i.e. isometric) to body mass. In contrast, MyHC and α-actin accumulated at a much greater rate (i.e. hyperallometric) than body mass (α=1.79 and 2.19 respectively) and MC volumes (α=1.76 and 1.45 respectively). CONCLUSION Changes in MC proteome and cell volumes measured in LP-FACS purified MCs are proportional to body mass post-weaning. Oppositely, MyHC and α-actin are concentrated more rapidly than what would be expected from MC proteome accumulation, cell enlargement, or animal growth alone. LP-FACS provides a new standard for adult MC purification and an approach to scale the biochemical content of specific proteins or group of proteins per cell in enlarging MCs.

  • Ca(2+)/calmodulin-activated phosphodiesterase 1A is highly expressed in rabbit cardiac sinoatrial nodal cells and regulates pacemaker function.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2016-07-02
    Yevgeniya O Lukyanenko,Antoine Younes,Alexey E Lyashkov,Kirill V Tarasov,Daniel R Riordon,Joonho Lee,Syevda G Sirenko,Evgeny Kobrinsky,Bruce Ziman,Yelena S Tarasova,Magdalena Juhaszova,Steven J Sollott,David R Graham,Edward G Lakatta

    Constitutive Ca(2+)/calmodulin (CaM)-activation of adenylyl cyclases (ACs) types 1 and 8 in sinoatrial nodal cells (SANC) generates cAMP within lipid-raft-rich microdomains to initiate cAMP-protein kinase A (PKA) signaling, that regulates basal state rhythmic action potential firing of these cells. Mounting evidence in other cell types points to a balance between Ca(2+)-activated counteracting enzymes, ACs and phosphodiesterases (PDEs) within these cells. We hypothesized that the expression and activity of Ca(2+)/CaM-activated PDE Type 1A is higher in SANC than in other cardiac cell types. We found that PDE1A protein expression was 5-fold higher in sinoatrial nodal tissue than in left ventricle, and its mRNA expression was 12-fold greater in the corresponding isolated cells. PDE1 activity (nimodipine-sensitive) accounted for 39% of the total PDE activity in SANC lysates, compared to only 4% in left ventricular cardiomyocytes (LVC). Additionally, total PDE activity in SANC lysates was lowest (10%) in lipid-raft-rich and highest (76%) in lipid-raft-poor fractions (equilibrium sedimentation on a sucrose density gradient). In intact cells PDE1A immunolabeling was not localized to the cell surface membrane (structured illumination microscopy imaging), but located approximately within about 150nm inside of immunolabeling of hyperpolarization-activated cyclic nucleotide-gated potassium channels (HCN4), which reside within lipid-raft-rich microenvironments. In permeabilized SANC, in which surface membrane ion channels are not functional, nimodipine increased spontaneous SR Ca(2+) cycling. PDE1A mRNA silencing in HL-1 cells increased the spontaneous beating rate, reduced the cAMP, and increased cGMP levels in response to IBMX, a broad spectrum PDE inhibitor (detected via fluorescence resonance energy transfer microscopy). We conclude that signaling via cAMP generated by Ca(2+)/CaM-activated AC in SANC lipid raft domains is limited by cAMP degradation by Ca(2+)/CaM-activated PDE1A in non-lipid raft domains. This suggests that local gradients of [Ca(2+)]-CaM or different AC and PDE1A affinity regulate both cAMP production and its degradation, and this balance determines the intensity of Ca(2+)-AC-cAMP-PKA signaling that drives SANC pacemaker function.

  • Targeting acid sphingomyelinase reduces cardiac ceramide accumulation in the post-ischemic heart.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2016-03-02
    Martina Klevstig,Marcus Ståhlman,Annika Lundqvist,Margareta Scharin Täng,Per Fogelstrand,Martin Adiels,Linda Andersson,Richard Kolesnick,Anders Jeppsson,Jan Borén,Malin C Levin

    Ceramide accumulation is known to accompany acute myocardial ischemia, but its role in the pathogenesis of ischemic heart disease is unclear. In this study, we aimed to determine how ceramides accumulate in the ischemic heart and to determine if cardiac function following ischemia can be improved by reducing ceramide accumulation. To investigate the association between ceramide accumulation and heart function, we analyzed myocardial left ventricle biopsies from subjects with chronic ischemia and found that ceramide levels were higher in biopsies from subjects with reduced heart function. Ceramides are produced by either de novo synthesis or hydrolysis of sphingomyelin catalyzed by acid and/or neutral sphingomyelinase. We used cultured HL-1 cardiomyocytes to investigate these pathways and showed that acid sphingomyelinase activity rather than neutral sphingomyelinase activity or de novo sphingolipid synthesis was important for hypoxia-induced ceramide accumulation. We also used mice with a partial deficiency in acid sphingomyelinase (Smpd1(+/-) mice) to investigate if limiting ceramide accumulation under ischemic conditions would have a beneficial effect on heart function and survival. Although we showed that cardiac ceramide accumulation was reduced in Smpd1(+/-) mice 24h after an induced myocardial infarction, this reduction was not accompanied by an improvement in heart function or survival. Our findings show that accumulation of cardiac ceramides in the post-ischemic heart is mediated by acid sphingomyelinase. However, targeting ceramide accumulation in the ischemic heart may not be a beneficial treatment strategy.

  • Fibroblast-myocyte coupling in the heart: Potential relevance for therapeutic interventions.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2016-01-18
    Emily Ongstad,Peter Kohl

    Cardiac myocyte-fibroblast electrotonic coupling is a well-established fact in vitro. Indirect evidence of its presence in vivo exists, but few functional studies have been published. This review describes the current knowledge of fibroblast-myocyte electrical signaling in the heart. Further research is needed to understand the frequency and extent of heterocellular interactions in vivo in order to gain a better understanding of their relevance in healthy and diseased myocardium. It is hoped that associated insight into myocyte-fibroblast coupling in the heart may lead to the discovery of novel therapeutic targets and the development of agents for improving outcomes of myocardial scarring and fibrosis.

  • Low shear stress induces M1 macrophage polarization in murine thin-cap atherosclerotic plaques.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-11-03
    Anusha N Seneviratne,Jennifer E Cole,Michael E Goddard,Inhye Park,Zahra Mohri,Stephen Sansom,Irina Udalova,Rob Krams,Claudia Monaco

    Macrophages, a significant component of atherosclerotic plaques vulnerable to acute complications, can be pro-inflammatory (designated M1), regulatory (M2), lipid- (Mox) or Heme-induced (Mhem). We showed previously that low (LSS) and oscillatory (OSS) shear stress cause thin-cap fibroatheroma and stable smooth muscle cell-rich plaque formation respectively in ApoE-knockout (ApoE(-/-)) mice. Here we investigated whether different shear stress conditions relate to specific changes in macrophage polarization and plaque morphology by applying a shear stress-altering cast to the carotid arteries of high fat-fed ApoE(-/-) mice. The M1 markers iNOS and IRF5 were highly expressed in macrophage-rich areas of LSS lesions compared to OSS lesions 6weeks after cast placement, while the M2 marker Arginase-1, and Mox/Mhem markers HO-1 and CD163 were elevated in OSS lesions. Our data indicates shear stress could be an important determinant of macrophage polarization in atherosclerosis, with low shear promoting M1 programming.

  • Characterization of the cardiac succinylome and its role in ischemia-reperfusion injury.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-09-22
    Jennifer A Boylston,Junhui Sun,Yong Chen,Marjan Gucek,Michael N Sack,Elizabeth Murphy

    Succinylation refers to modification of lysine residues with succinyl groups donated by succinyl-CoA. Sirtuin5 (Sirt5) is a mitochondrial NAD(+)-dependent deacylase that catalyzes the removal of succinyl groups from proteins. Sirt5 and protein succinylation are conserved across species, suggesting functional importance of the modification. Sirt5 loss impacts liver metabolism but the role of succinylation in the heart has not been explored. We combined affinity enrichment with proteomics and mass spectrometry to analyze total succinylated lysine content of mitochondria isolated from WT and Sirt5(-/-) mouse hearts. We identified 887 succinylated lysine residues in 184 proteins. 44 peptides (5 proteins) occurred uniquely in WT samples, 289 (46 proteins) in Sirt5(-/-) samples, and 554 (133 proteins) were common to both groups. The 46 unique proteins in Sirt5(-/-) heart participate in metabolic processes such as fatty acid β-oxidation (Eci2) and branched chain amino acid catabolism, and include respiratory chain proteins (Ndufa7, 12, 13, Dhsa). We performed label-free analysis of the peptides common to WT and Sirt5(-/-) hearts. 16 peptides from 9 proteins were significantly increased in Sirt5(-/-) by at least 30%. The adenine nucleotide transporter 1 showed the highest increase in succinylation in Sirt5(-/-) (108.4 fold). The data indicate that succinylation is widespread in the heart and enriched in metabolic pathways. We examined whether the loss of Sirt5 would impact ischemia-reperfusion (I/R) injury and we found an increase in infarct size in Sirt5(-/-) hearts compared to WT littermates (68.5(+)/-1.1% Sirt5(-/-) vs 39.6(+)/(-) 6.8% WT) following 20min of ischemia and 90-min reperfusion. We further demonstrate that I/R injury in Sirt5(-/-) heart is restored to WT levels by pretreatment with dimethyl malonate, a competitive inhibitor of succinate dehydrogenase (SDH), implicating alteration in SDH activity as causative of the injury.

  • Real-time relationship between PKA biochemical signal network dynamics and increased action potential firing rate in heart pacemaker cells: Kinetics of PKA activation in heart pacemaker cells.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-08-05
    Yael Yaniv,Ambhighainath Ganesan,Dongmei Yang,Bruce D Ziman,Alexey E Lyashkov,Andre Levchenko,Jin Zhang,Edward G Lakatta

    cAMP-PKA protein kinase is a key nodal signaling pathway that regulates a wide range of heart pacemaker cell functions. These functions are predicted to be involved in regulation of spontaneous action potential (AP) generation of these cells. Here we investigate if the kinetics and stoichiometry of increase in PKA activity match the increase in AP firing rate in response to β-adrenergic receptor (β-AR) stimulation or phosphodiesterase (PDE) inhibition, that alters the AP firing rate of heart sinoatrial pacemaker cells. In cultured adult rabbit pacemaker cells infected with an adenovirus expressing the FRET sensor AKAR3, the EC50 in response to graded increases in the intensity of β-AR stimulation (by Isoproterenol) the magnitude of the increases in PKA activity and the spontaneous AP firing rate were similar (0.4±0.1nM vs. 0.6±0.15nM, respectively). Moreover, the kinetics (t1/2) of the increases in PKA activity and spontaneous AP firing rate in response to β-AR stimulation or PDE inhibition were tightly linked. We characterized the system rate-limiting biochemical reactions by integrating these experimentally derived data into a mechanistic-computational model. Model simulations predicted that phospholamban phosphorylation is a potent target of the increase in PKA activity that links to increase in spontaneous AP firing rate. In summary, the kinetics and stoichiometry of increases in PKA activity in response to a physiological (β-AR stimulation) or pharmacological (PDE inhibitor) stimuli match those of changes in the AP firing rate. Thus Ca(2+)-cAMP/PKA-dependent phosphorylation limits the rate and magnitude of increase in spontaneous AP firing rate.

  • Assessment of cardiac function in mice lacking the mitochondrial calcium uniporter.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-06-10
    Kira M Holmström,Xin Pan,Julia C Liu,Sara Menazza,Jie Liu,Tiffany T Nguyen,Haihui Pan,Randi J Parks,Stasia Anderson,Audrey Noguchi,Danielle Springer,Elizabeth Murphy,Toren Finkel

    Mitochondrial calcium is thought to play an important role in the regulation of cardiac bioenergetics and function. The entry of calcium into the mitochondrial matrix requires that the divalent cation pass through the inner mitochondrial membrane via a specialized pore known as the mitochondrial calcium uniporter (MCU). Here, we use mice deficient of MCU expression to rigorously assess the role of mitochondrial calcium in cardiac function. Mitochondria isolated from MCU(-/-) mice have reduced matrix calcium levels, impaired calcium uptake and a defect in calcium-stimulated respiration. Nonetheless, we find that the absence of MCU expression does not affect basal cardiac function at either 12 or 20months of age. Moreover, the physiological response of MCU(-/-) mice to isoproterenol challenge or transverse aortic constriction appears similar to control mice. Thus, while mitochondria derived from MCU(-/-) mice have markedly impaired mitochondrial calcium handling, the hearts of these animals surprisingly appear to function relatively normally under basal conditions and during stress.

  • So! What's aging? Is cardiovascular aging a disease?
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-04-15
    Edward G Lakatta

    "Inside every old person is a young person wondering what happened." So, what is aging? Aging is a manifestation of progressive, time-dependent failure of molecular mechanisms that create disorder within a system of DNA and its environment (nuclear, cytosolic, tissue, organ, organism, other organisms, society, terra firma, atmosphere, universe). Continuous signaling, transmitted with different kinetics across each of these environments, confers a "mutual enslavement" that creates ordered functions among the components within the system. Accrual of this molecular disorder over time, i.e. during aging, causes progressive changes in the structure and function of the heart and arteries that are quite similar in humans, non-human primates, rabbits and rats that compromise cardiovascular reserve function, and confer a marked risk for incident cardiovascular disease. Nearly all aspects of signaling within the DNA environment system within the heart and arteries become disordered with advancing age: Signals change, as does sensing of the signals, transmission of signals and responses to signals, impaired cell renewal, changes in the proteome due to alterations in genomic transcription, mRNA translation, and proteostasis. The density of some molecules becomes reduced, and post-translational modifications, e.g. oxidation and nitration phosphorylation, lead to altered misfolding and disordered molecular interactions. The stoichiometry and kinetics of enzymatic and those reactions which underlie crucial cardiac and vascular cell functions and robust reserve mechanisms that remove damaged organelles and proteins deteriorate. The CV cells generate an inflammatory defense in an attempt to limit the molecular disorder. The resultant proinflammatory milieu is not executed by "professional" inflammatory cells (i.e. white blood cells), however, but by activation of renin-angiotensin-aldosterone endothelin signaling cascades that leads to endothelial and vascular smooth muscle and cardiac cells' phenotype shifts, resulting in production of inflammatory cytokines. Progressive molecular disorder within the heart and arteries over time leads to an excessive allostatic load on the CV system, that results in an increase and "overshoot" in the inflammatory defense signaling. This age-associated molecular disorder-induced inflammation that accrues in the heart and arteries does not, itself, cause clinical signs or symptoms of CVD. Clinical signs and symptoms of these CVDs begin to emerge, however, when the age-associated inflammation in the heart and arteries exceeds a threshold. Thus, an emerging school of thought is that accelerated age-associated alterations within the heart and arteries, per se, ought to be considered to be a type of CVD, because the molecular disorder and the inflammatory milieu it creates within the heart and arteries with advancing age are the roots of the pathophysiology of most cardiovascular diseases, e.g. athersclerosis and hypertension. Because many effects of aging on the CV system can be delayed or attenuated by changes in lifestyle, e.g. diet and exercise, or by presently available drugs, e.g. those that suppress Ang II signaling, CV aging is a promising frontier in preventive cardiology that is not only ripe for, but also in dire need of attention! There is an urgency to incorporate the concept of cardiovascular aging as a disease into clinical medicine. But, sadly, the reality of the age-associated molecular disorder within the heart and ateries has, for the most part, been kept outside of mainstream clinical medicine. This article is part of a Special Issue entitled CV Aging.

  • Age-associated pro-inflammatory remodeling and functional phenotype in the heart and large arteries.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-02-11
    Mingyi Wang,Ajay M Shah

    The aging population is increasing dramatically. Aging-associated stress simultaneously drives proinflammatory remodeling, involving angiotensin II and other factors, in both the heart and large arteries. The structural remodeling and functional changes that occur with aging include cardiac and vascular wall stiffening, systolic hypertension and suboptimal ventricular-arterial coupling, features that are often clinically silent and thus termed a silent syndrome. These age-related effects are the result of responses initiated by cardiovascular proinflammatory cells. Local proinflammatory signals are coupled between the heart and arteries due to common mechanical and humoral messengers within a closed circulating system. Thus, targeting proinflammatory signaling molecules would be a promising approach to improve age-associated suboptimal ventricular-arterial coupling, a major predisposing factor for the pathogenesis of clinical cardiovascular events such as heart failure.

  • Noncoding RNA in age-related cardiovascular diseases.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2015-02-03
    Simona Greco,Myriam Gorospe,Fabio Martelli

    Eukaryotic gene expression is tightly regulated transcriptionally and post-transcriptionally by a host of noncoding (nc)RNAs. The best-studied class of short ncRNAs, microRNAs, mainly repress gene expression post-transcriptionally. Long noncoding (lnc)RNAs, which comprise RNAs differing widely in length and function, can regulate gene transcription as well as post-transcriptional mRNA fate. Collectively, ncRNAs affect a broad range of age-related physiologic deteriorations and pathologies, including reduced cardiovascular vigor and age-associated cardiovascular disease. This review presents an update of our understanding of regulatory ncRNAs contributing to cardiovascular health and disease as a function of advancing age. We will discuss (1) regulatory ncRNAs that control aging-associated cardiovascular homeostasis and disease, (2) the concepts, approaches, and methodologies needed to study regulatory ncRNAs in cardiovascular aging and (3) the challenges and opportunities that age-associated regulatory ncRNAs present in cardiovascular physiology and pathology. This article is part of a Special Issue entitled "CV Aging".

  • Solving mitochondrial mysteries.
    J. Mol. Cell. Cardiol. (IF 5.055) Pub Date : 2014-12-03
    Elizabeth Murphy

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