Lianghui You

Adipogenic miRNA and meta-signature miRNAs involved in human adipocyte differentiation and obesity

MicroRNAs (miRNAs) have been identified as a new class of regulatory molecules that influence many biological functions, including metabolism, adipocyte differentiation. To determine the role of adipogenic miRNAs in the adipocyte differentiation process, we used microarray technology to monitor miRNA levels in human adipose-derived mesenchymal stem cells (hMSCs-Ad), human stromal vascular cells (SVCs) and differentiated adipocytes. 79 miRNAs were found to be differentially expressed, most of which are located in obesity related chromosomal regions but have not been previously linked to adipocyte differentiation process. A systematic search was made for relevant studies in academic data bases, involving the Gene Expression Omnibus (GEO) ArrayExpress, Pubmed and Embase database. Eight studies on human adipocyte differentiation or obesity were included in the final analysis. After combining our microarray data with meta-analysis of published microarray data, we detected 42 differently expressed miRNAs (meta-signature miRNAs) in mature adipocytes compared to SVCs or hMSCs-Ad. Our study shows meta-signature miRNAs specific for adipogenesis, several of which are correlated with key gene targets demonstrating functional relationships to pathways in BMP signaling pathway, Cell differentiation, Wnt signaling, insulin receptor signaling pathway, MAPK signaling, Cell cycle and lipid metabolic process. Our study shows that the first evidence of hsa-let-7 family, hsa-miR-15a-5p, hsa-miR-27a-3p, hsa-miR-106b-5p, hsa-miR-148a-3p and hsa-miR-26b-5p got a great weight in adipogenesis. We concluded that meta-signature miRNAs involved in adipocyte differentiation and provided pathophysiological roles and novel insight into obesity and its related metabolic diseases.

Peptidome analysis of human milk from women delivering macrosomic fetuses reveals multiple means of protection for infants

Breastfeeding is associated with a lower incidence of obesity, diabetes, and cardiovascular disease later in life. While macrosomic infants have a higher risk of developing obesity and other metabolic disorders. Breast milk may contain special nutrients to meet the different growth needs of different infants. Whether mothers make breast milk different to meet the requirement of macrosomic infants is still unknown. Here, we conducted a comparison between mothers delivering macrosomic and non-macrosomic infants in colostrum endogenous peptides. More than 400 peptides, originating from at least 34 protein precursors, were identified by Liquid Chromatography/Mass Spectrometry (LC/MS). Out of these, 29 peptides found to be significant differently expressed (|fold change| ≥ 3, P < 0.01). Blastp analysis revealed 41 peptides may have established biological activities, which exhibit immunomodulating, antibacterial action, antioxidation, opioid agonist and antihypertensive activity. Furthermore, we found that peptide located at β-Casein 24-38 AA has antimicrobial effect against E. coli, Y. enterocolitica and S. aureus. While, κ-Casein 89-109 AA-derived peptide plays as a regulator of preadipocyte proliferation. The profile of endogenous peptides from macrosomic term infants is different from non-macrosomic terms. This different peptide expression potentially has specific physiological function to benefit macrosomic infants. Finally, we believe that our research is a meaningfull finding which may add to the understanding of milk peptide physiological action.

MiR-1275 inhibits adipogenesis via ELK1 and its expression decreases in obese subjects

Excessive adipocyte differentiation and proliferation are closely associated with the onset of obesity, which has been partially linked to microRNA expression. In previous studies, using miRNA microarray screening, we found that miR-1275 was significantly decreased in human mature adipocytes. In this study, we examined the role of miR-1275 in adipogenesis. Our results indicated that miR-1275 can inhibit the differentiation of human visceral preadipocytes without affecting their proliferation. ELK1, an E-twenty-six (ETS)-domain transcription factor associated with adipocyte differentiation, was strongly suppressed by miR-1275 in human visceral adipocytes. This was demonstrated via a dual-luciferase reporter assay and pointed to ELK1 as a direct target of miR-1275. Furthermore, miR-1275 expression was significantly diminished in the visceral adipose tissue of overweight and obese human subjects accompanied by a negative correlation with body mass index. These results suggest that miR-1275 could play a future role in the management of obesity, as a novel therapeutic target or biomarker.

Change in circulating microRNA profile of obese children indicates future risk of adult diabetes

PURPOSE Childhood obesity increases susceptibility to type 2 diabetes (T2D) in adults. Circulating microRNAs (miRNAs) in serum have been proposed as potential diagnostic biomarkers, and they may contribute to the progression toward T2D. Here, we investigated the possibility of predicting the future risk of adult T2D in obese children by using circulating miRNAs. BASIC PROCEDURES We performed miRNA high-throughput sequencing to screen relevant circulating miRNAs in obese children. The expression patterns of targeted miRNAs were further explored in obese children and adults with T2D. To investigate the underlying contributions of these miRNAs to the development of T2D, we detected the impacts of the candidate miRNAs on preadipocyte proliferation, insulin secretion by pancreatic β-cell, and glucose uptake by skeletal muscle cells. MAIN FINDINGS Three miRNAs (miR-486, miR-146b and miR-15b), whose expression in the circulation was most dramatically augmented in obese children and adult T2D patients, were selected for further investigation. Of these 3 miRNAs, miR-486 was implicated in accelerating preadipocyte proliferation and myotube glucose intolerance, miR-146b and miR-15b were engaged in the suppression of high concentration glucose-induced pancreatic insulin secretion, and they all contributed to the pathological processes of obesity and T2D. PRINCIPAL CONCLUSIONS Our results provide a better understanding of the role of circulating miRNAs, particularly miR-486, miR-146b and miR-15b, in predicting the future risk of T2D in obese children.

A transcribed ultraconserved noncoding RNA, uc.417, serves as a negative regulator of brown adipose tissue thermogenesis

Brown adipose tissue (BAT) oxidizes fatty acids for thermogenesis and could therefore be considered as part of a new strategy in combating obesity and associated metabolic diseases. It is well established that aging is accompanied by a decline of brown adipocyte regenerative capacity. How aging contributes to this loss is poorly understood. Here, we identify a long noncoding RNA, uc.417, which is transcribed from an ultraconserved region in rodents. Expression of uc.417 increases with age. Ectopic expression of uc.417 impairs adipogenesis and the thermogenic program in brown adipocytes. However, uc.417 is not required for brown fat function. In vivo, uc.417 attenuates the cold‐induced thermogenic programin mouse BAT. Moreover, we find that uc.417 moderately inhibits phosphorylation of p38MAPK without affecting the total protein level of p38MAPK. The p38MAPK pathway is essential for activating BAT to stimulate uncoupling protein 1 gene expression. The data point to uc.417 as being an important factor in an age‐dependent loss of function of brown adipose tissue.—Cui, X., You, L., Li, Y., Zhu, L., Zhang, F., Xie, K., Cao, Y., Ji, C., Guo, X. A transcribed ultraconserved noncoding RNA, uc.417, serves as a negative regulator of brown adipose tissue thermogenesis. FASEB J. 30, 4301–4312 (2016). www.fasebj.org

Expression of miR-199a-3p in human adipocytes is regulated by free fatty acids and adipokines

Obesity is associated with a notable risk for disease, including risk of cardiovascular disorders, type 2 diabetes mellitus (T2DM) and hypertension. Adipose tissue modulates the metabolism by releasing free fatty acids (FFAs) and adipokines, including leptin, resistin, tumor necrosis factor-α (TNF-α) and interleukin 6 (IL-6). Altered secretion patterns of FFAs and adipokines have been demonstrated to result in obesity-associated insulin resistance (IR) and inflammatory responses. MicroRNA-199a-3p (miR)-199a-3p expression is significantly induced in differentiated human adipose-derived mesenchymal stem cells and indicates the association with T2DM. However, the association between miR-199a-3p levels in adipocytes and obesity-associated IR, as well as inflammatory responses remains to be elucidated. The present study observed an elevation of miR-199a-3p expression level in mature human adipocytes (visceral) compared with pre-adipocytes. In addition, miR-199a-3p expression was higher in visceral adipose deposits from obese subjects. FFA, TNF-α, IL-6 and leptin significantly induced miR-199a-3p expression in mature human adipocytes, while resistin had the opposite effect. miR-199a-3p may represent a factor in the modulation of obesity-associated IR and inflammatory responses.

GM13133 Is a Negative Regulator in Mouse White Adipocytes Differentiation and Drives the Characteristics of Brown Adipocytes.

Obesity is tightly associated with the disturbance of white adipose tissue storing excess energy. Thermogenic adipocytes (brown and beige) exert a critical role of oxidizing nutrients at the high rates through non‐shivering thermogenesis. The recruitment of brown characteristics in white adipocytes, termed browning, has been considered as a promising strategy for treating obesity and associated metabolic complications. Recently, long noncoding RNAs play a crucial role in regulating tissue development and participating in disease pathogenesis, yet their effects on the conversion of white into brown‐like adipocytes and thermogenic function were not totally understood. Here, we identified a mouse brown adipose specific expressed lncRNA, termed GM13133. Moreover, a considerable amount of GM13133 is expressed in adipocytes and actively modulated by cold, β3‐adrenergic agonist and cAMP stimuli, implying a potential role in the conversion from white to brown adipocytes. Overexpression of GM13133 did not affect the proliferation of mouse white pre‐adipocytes, but inhibited white adipocyte differentiation by decreasing lipid accumulation. The forced expression of GM13133 also significantly drove the conversion of white into brown‐like adipocytes with the enhanced mitochondrial biogenesis and the induced expression of brown adipocytes specific markers. A global mRNA analysis further indicated the possible regulatory role of cAMP signaling pathway in GM13133 mediated white‐to‐brown adipocytes conversion. Our results identified a lncRNA‐mediated modulation in primary mouse white adipocyte differentiation and indicate the functional significance of GM13133 in promoting browning of white adipocytes and maintenance of thermogenesis, further providing a potential strategy to treating obesity.

Downregulation of Long Noncoding RNA Gas5 Affects Cell Cycle and Insulin Secretion in Mouse Pancreatic β Cells

Background: Evidence shows that long non-coding RNAs (lncRNAs) are involved in individual development, cell differentiation, cell cycle processes and other important life processes and are closely related to major human diseases, including diabetes. Recent studies have reported that lncRNAs are involved in β cell functions and that lncRNA Gas5 levels decreased in T2DM patients’ serum. The purpose of this study was to clarify the role of lncRNA Gas5 in mouse β cell functions in vitro and in vivo. Methods: lncRNA Gas5 expression in T2DM and normal mouse tissues was analyzed using qRT-PCR. RNAi, qRT-PCR, Annexin V-FITC assays, western blot, GSIS and RIA were performed to detect the effects of lncRNA Gas5 on insulin synthesis and secretion in vitro and in vivo. Results: The lncRNA Gas5 level was significantly decreased in db/db mice. However, lncRNA Gas5 expression was relatively high in the pancreas of normal mice. Knockdown of lncRNA Gas5 expression led to cell cycle G1 arrest and impaired insulin synthesis and secretion in Min6 cells. Further, knockdown of lncRNA Gas5 expression in primary isolated islets resulted in decreased expression of insulin gene and transcription factors, Pdx1 and MafA. These results indicate that lncRNA Gas5 might perform as a new regulator, maintaining β cell identity and function by affecting insulin synthesis and secretion.

Identification and characterization of NF-kappaB binding sites in human miR-1908 promoter.

BACKGROUND Previous studies reported that miR-1908 was highly expressed in mature human adipocytes. Adipokines tumor necrosis factor α (TNF-α) that was known to activate NF-kappaB signaling could affect the expression of miR-1908 in adipocytes. However, little is known about the underlying mechanisms. METHODS In this study, we identified miR-1908 promoter using polymerase chain reaction (PCR) from human genomic DNA. Bioinformatic analysis was applied to predict the NF-kappaB binding sites in miR-1908 promoter. Real-time PCR, dual luciferase reporter assay, Mutagenesis analysis and electrophoretic mobility shift assay (EMSA) were performed to demonstrate the function of NF-kappaB binding sites in miR-1908 promoter. RESULTS 1243bp miR-1908 promoter located in the intron of host gene fatty acid desaturase 1 (FADS1). Bioinformatic analysis revealed the presence of two putative NF-kappaB binding sites. TNF-α restricts miR-1908 expression in preadipocytes, and TNF-α decreases miR-1908 promoter activity in HEK293T cells. In addition, those two NF-kappaB transcription factor binding sites in miR-1908 promoter were functional. CONCLUSION Our findings demonstrated that miR-1908 has its own transcription unit, and revealed the transcriptional mechanisms of miR-1908 expression based on NF-kappaB signaling. This study offers a theoretical basis for understanding the transcriptional mechanism of miR-1908 expression and may provide a new strategy for obesity clinical therapy.

Maternal Vitamin D Status and Risk of Gestational Diabetes: a Meta-Analysis

Background/Aims: Whether maternal vitamin D deficiency is associated with gestational diabetes remains controversial. This meta-analysis aimed to systematically evaluate published evidence on the association between maternal vitamin D status and the risk of gestational diabetes. Methods: We retrieved relevant articles from the PubMed, Medline and Embase databases up to May 2017 for observational studies investigating the association between vitamin D status and the risk of gestational diabetes. Odds ratios (OR) or risk ratios (RR) from individual studies were pooled using the fixed and random effect models. Results: The meta-analysis of 29 observational studies included 28,982 participants, of which 4,634 were diagnosed with gestational diabetes, and showed that maternal vitamin D insufficiency was associated with a significantly increased risk of gestational diabetes by 39% (pooled OR = 1.39, 95%CI = 1.20-1.60) with moderate heterogeneity (I2 = 50.2%; P = 0.001). Moreover, the 25(OH)D level was significantly lower in gestational diabetes cases than in controls with a pooled effect of -4.79 nmol/L (95% CI = -6.43, -3.15). Significant heterogeneity was also detected (I2 = 65.0%, P < 0.001). Further subgroup analysis indicated that this association was also evident in most subpopulations. Conclusion: This meta-analysis indicated a significant association between vitamin D insufficiency and increased risk of gestational diabetes. Further well-designed large-scale clinical trials are essential to verify this association.