Elsevier

Life Sciences

Volume 265, 15 January 2021, 118762
Life Sciences

Ad36 promotes differentiation of hADSCs into brown adipocytes by up-regulating LncRNA ROR

https://doi.org/10.1016/j.lfs.2020.118762Get rights and content

Abstract

Aims

This study is to investigate the role of adenovirus type 36 (Ad36) in inducing differentiation of human adipose-derived stem cells (hADSCs) into brown adipocytes.

Main methods

The hADSCs were induced to differentiate into adipocytes by a cocktail method and Ad36, respectively. They were collected on the 2nd, 4th, 6th, and 8th day, respectively. LncRNA ROR was silenced by siRNA. RT-qPCR and Western-blot were used to detect the mRNA and protein levels. Transmission electron microscopy was used to observe the mitochondria.

Key findings

The mRNA and protein expression levels of LncRNA ROR, Cidea, Dio2, Fgf21, Ucp1, Prdm16, Cox5b, Atp5o, Atp6, and Nd2 in the Ad36 induction group were significantly higher than those in the cocktail induction group. The expression levels of Leptin mRNA and protein in the Ad36 induction group were significantly lower than those in the cocktail induction group. After siRNA knockdown of LncRNA ROR, mRNA and protein expression levels of Cidea, Dio2, Fgf21, Ucp1, Prdm16, Cox5b, Atp5o, Atp6 and Nd2 were significantly lower than the control group during the induction of hADSC differentiation into adipocytes by Ad36. Additionally, mitochondria in the Ad36 induction group was increased compared to that in the cocktail induction group.

Significance

Ad36 may promote the differentiation of hADSCs into brown adipocytes by up-regulating LncRNA ROR.

Introduction

Obesity is a chronic metabolic disease caused by various genetic and environmental factors, featured by weight gain and excessive accumulation and/or abnormal distribution of fat in the body. Obesity is closely related to various diseases such as Type 2 diabetes, dyslipidemia, hypertension, coronary heart disease, stroke and tumor [1,2].

Adenovirus is an icosahedral, non-enveloped, double-stranded DNA virus family with a diameter ranging from 65 nm to 80 nm. Based on the hemagglutination properties and sequence homology, they are divided into 7 subgroups of A, B, C, D, E, F and G [3]. Ad36 belongs to subgroup D and is related to obesity. It is generally believed that obesity will lead to insulin resistance and then blood glucose and lipid disorders. However, recent studies have reported that humans have increased weight and body fat after infection with Ad36, but have relatively low blood lipids and easy control of blood glucose [4,5]. In a previous study of our group, we used Ad36 and high-fat diet to establish a diet-induced obese mouse model [6]. Compared with the control group and high-fat diet group, Ad36 induced obese mice had more but smaller fat cells [6]. The above results suggest that although Ad36 can induce adipocyte differentiation and obesity, it is unclear whether Ad36 has the ability to induce hADSCs to differentiate into brown adipocytes or promote browning of adipocytes.

Adipocyte differentiation is a complex and delicate process of gene expression regulation. Brown adipose tissue (BAT) is rich in mitochondrial uncoupling protein 1 (UCP1). UCP1 is located on the mitochondrial inner membrane of brown adipocytes. It is a functional protein of BAT for heat production, and its expression level represents the function of BAT [7]. Its function is to uncouple the electron transport of the respiratory chain and ADP phosphorylation, thereby converting the electrochemical potential energy in the mitochondrial proton gradient into heat. UCP1 is a major driver of heat production by mammalian fat, and it is shown that the heat production by UCP1 can reduce obesity and increase insulin sensitivity [8]. PRDM16 (PR domain containing 16), which regulates the differentiation, heat production and energy consumption of brown adipocytes, plays a key role in the development of brown adipocytes and is believed to be a switch that regulates the development of Myf5+ precursor cells into muscle cells or brown adipocytes [9]. During the differentiation process of brown adipocytes, multiple transcriptional regulatory links are involved, and key genes, such as CIDEA [10], DIO2 [11] and PGC-1α [12], promote the browning differentiation and selective expression of thermogenic genes. However, the role of Ad36 in inducing differentiation of human adipose-derived stem cells (hADSCs) into brown adipocytes is unclear, and the expression of the above marker genes during this process has not been reported.

Long noncoding RNA regulator of reprogramming (LncRNA ROR) is highly expressed in embryonic stem cells and induced pluripotent stem cells (iPSCs) [11]. Recent studies have shown that LncRNA ROR can maintain the pluripotency of human amniotic epithelial cells and improve their efficiency in differentiating into islet β cells, and it has been demonstrated in diabetic patients and animal models that LncRNA ROR can help restore islet functions [12,13]. The preliminary RNA-seq results of our group (data not published) showed that the relative expression of LncRNA ROR in the Ad36 induction group was 5.25 times higher than that in the cocktail induction group during the differentiation of hADSC into adipocytes. These results suggest that LncRNA ROR may play a role in Ad36-induced hADSC differentiation.

Herein, we aim to investigate the role and mechanism of Ad36 in the induction of brown adipocyte differentiation. Ad36 and a cocktail method were used to induce the differentiation of hADSCs into brown adipocytes. The results indicate that Ad36 may play a role in the differentiation of hADSCs into brown adipocytes through LncRNA ROR.

Section snippets

Cell isolation

The human adipose derived stem cells (hADSCs) were isolated from the subcutaneous adipose tissues of patients who underwent plastic surgery in the department of burn and plastic surgery, the First Affiliated Hospital of Xinjiang Medical University. Clinical and biochemical examinations confirmed that these subjects did not have acute inflammation, cancers, endocrine diseases or infectious diseases. The study was conducted under the hospital ethics committee approval and informed consent from

The expression of LncRNA ROR and related genes during the induction of hADSCs

To assess the changes of mRNA and protein during the induction of hADSCs, RT-qPCR and Western blot was conducted, respectively. In the process of hADSC differentiation into adipocytes, LncRNA ROR (Fig. 1A), and the mRNA and protein expression of the brown adipocyte differentiation marker genes Cidea, Dio2, Fgf21, Ucp1 and Prdm16 (Figs. 1B–F, 2A, D–H), and the mitochondrial respiratory chain and oxidative phosphorylation-related enzyme genes Cox5b, Atp5o, Atp6 and Nd2 (Figs. 1G–J, 2B, I–L) in

Discussion

On a global scale, the prevalence of obesity is rising rapidly, and the adverse consequences associated with overweight and obesity continue to increase [1,2]. Our previous study [15] found that Ad36-infected Uighur obese patients showed decreased blood glucose and blood lipids. In vitro studies have shown that Ad36 increases glucose uptake in adipose tissue and skeletal muscle cells via the E4orf1 gene [5,16], which is the first open reading frame encoded by E4 (an early gene of Ad36).

Conclusion

In conclusion, Ad36 may up-regulate LncRNA ROR, thereby increasing the mRNA and protein expression levels of the brown fat marker genes Cidea, Dio2, Fgf21, Ucp1, Prdm16 and mitochondrial respiratory chain and oxidative phosphorylation-related enzyme genes Cox5b, Atp5o, Atp6 and Nd2 to promote the differentiation of hADSCs into brown adipocytes.

Funding

This work was supported by the National Natural Science Foundation of China [grant number 81873664, 81660154], Doctor Research Start Fund of Xinjiang Medical University, the Key Discipline of the 13th Five-Year Plan (Plateau Discipline) of Xinjiang Uygur Autonomous Region, and Karamay Innovation Talent Project (2017RC001A-21).

CRediT authorship contribution statement

YJ and LL carried out the experiments, analyzed data and drafted the manuscript. HG collected the clinical sample. JG, YX carried out the quantitative qRT-PCR, westerblot assay. XL, XM, NN carried out the knockdown of lincRNA ROR. YG designed the study, evaluated the data, and edited the manuscript for publication. All authors read and approved the final manuscript.

Declaration of competing interest

The authors declared no potential conflicts of interest.

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    Yi Jiao and Ling Liu contributed equally to this work.

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