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Gene-chip studies of adipogenesis-regulated microRNAs in mouse primary adipocytes and human obesity (Affymetrix)

ABSTRACT: Adipose tissue abundance relies partly on the factors that regulate adipogenesis, i.e. proliferation and differentiation of adipocytes. While the transcriptional program that initiates adipogenesis is well-known, the importance of microRNAs in adipogenesis is less well studied. We thus set out to investigate whether miRNAs would be actively modulated during adipogenesis and obesity. Several models exist to study adipogenesis in vitro, of which the cell line 3T3-L1 is probably the most well known, albeit not the most physiologically appropriate. We used a microarray strategy to provide a global profile of miRNAs in brown and white primary murine adipocytes (prior to and following differentiation) and evaluated the similarity of the responses to non-primary cell models, through literature data-mining. We found 65 miRNAs regulated during in vitro adipogenesis in primary adipocytes. When we compared our primary adipocyte profiles with those of cell lines reported in the literature, we found a high degree of difference in adipogenesis-regulated miRNAs. We evaluated the expression of 10 of our adipogenesis-regulated miRNAs using real-time qPCR and then selected 5 miRNAs that showed robust expression levels and profiled these by qPCR in subcutaneous adipose tissue of 20 humans with a range of body mass indices (BMI, range=21-48). Of the miRNAs tested, mir-21 was both highly expressed in human adipose tissue and positively correlated with BMI (R2=0.49, p<0.001). In conclusion, we provide the preliminary analysis of miRNAs important for primary cell in vitro adipogenesis and find that the inflammation-associated miRNA, mir-21, is up-regulated in subcutaneous adipose tissue in human obesity.

ORGANISM(S): Homo sapiens

PROVIDER: GSE27949 | GEO | 2011/05/31

SECONDARY ACCESSION(S): PRJNA141727

REPOSITORIES: GEO

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Project description:Aims: Adipocytes are critical cornerstones of energy metabolism. While obesity-induced adipocyte dysfunction is associated with insulin resistance and systemic metabolic disturbances, adipogenesis, the formation of new adipocytes and healthy adipose tissue expansion are associated with metabolic benefits. Understanding the molecular mechanisms governing adipogenesis is of great clinical potential to efficiently restore metabolic health in obesity. Here we investigate the role of Heart and neural crest derivatives-expressed protein 2 (HAND2) in adipogenesis. Methods: Human white adipose tissue (WAT) were collected in a cross-sectional study of 318 individuals. In vitro, for mechanistic experiments we used primary adipocytes from human and mice as well as human multipotent adipose derived stem (hMADS) cells. Gene silencing was performed using siRNA or genetic inactivation in primary adipocytes from LoxP mouse models with Cre-encoding mRNA. Adipogenesis efficiency was measured by OilRedO staining, qPCR and microarray. A combinatorial RNASeq approach was used to identify gene clusters regulated by HAND2. In vivo, we created a conditional adipocyte Hand2 deletion mouse model using Cre under control of the Adipoq promoter (HAND2AdipoqCRE). Results: We found that HAND2 is an obesity-linked white adipocyte transcription factor regulated by glucocorticoids that was required but insufficient for adipocyte differentiation in vitro. In a large cohort of humans with obesity, WAT HAND2 expression was correlated to body-mass-index (BMI). The HAND2 gene was enriched in white adipocytes compared to brown, induced early in differentiation and responded to DEX, a typical glucocorticoid receptor (GR, encoded by NR3C1) agonist. Silencing of NR3C1 in hMADS or deletion of GR in a transgenic conditional mouse model results in diminished HAND2 expression, establishing that adipocyte HAND2 is regulated by GCs via GR in vitro and in vivo. Furthermore, we identified gene clusters indirectly regulated by the GR-HAND2 pathway. Interestingly, silencing of HAND2 impaired adipocyte differentiation in hMADS and primary mouse adipocytes. However, a conditional adipocyte Hand2 deletion mouse model using Cre under control of the Adipoq promoter did not mirror these effects on adipose tissue differentiation, indicating that Hand2 was required at stages prior to Adipoq expression. Conclusion: In summary, our study identifies HAND2 as a novel obesity-linked adipocyte transcription factor, highlighting new mechanisms of GR-dependent adipogenesis in human and mice.

Project description:To better understand the scale of gene expression changes that occur during the formation of mature adipocytes from preadipocytes, we compared and characterised the transcriptome profile of mesenchymal stromal cells derived from human adipose tissue, otherwise known as adipose-derived stromal cells (ASCs), undergoing adipocyte differentiation on day 1, 7, 14 and 21 (representing the early to late stage process of adipogenesis). Microarray technique was systematically employed to study gene expression in adipose-derived stromal cells during adipogenic differentiation over a 21 day period to identify genes that are important in driving adipogenesis in humans. We have undertaken an in-depth transcriptome analysis of adipogenesis in human adipose-derived stromal cells (ASCs) induced to differentiate into adipocytes in vitro. Genes were differentially expressed on days 1, 7, 14 and 21 post-induction and numbered 128, 218, 253 and 240 respectively. Up-regulated genes were associated with neural and blood vessel development, leukocyte migration, and tumor growth, invasion and metastasis. They also shared common pathways with certain obesity-related pathophysiological conditions. Down-regulated genes were associated with osteogenesis and the immune response. KLF15, LMO3, FOXO1 and ZBTB16 transcription factors were up-regulated throughout the differentiation process. CEBPA, PPARG, ZNF117, MLXIPL, MMP3 and RORB were up-regulated only on days 14 - 21, which coincides with the maturation of adipocytes and could possibly serve as candidates for controlling fat accumulation and the size of mature adipocytes. We identified genes that were up-regulated only on day 1 - 7 and day 14 - 21 that could serve as potential early and late-stage differentiation markers. This study reveals potential markers for the different stages in ASC adipogenic differentiation which could serve as good candidates to combat obesity and further link the biology of fat cell formation to the co-morbidities of obesity.

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Gene-chip studies of adipogenesis-regulated microRNAs in mouse primary adipocytes and human obesity (Affymetrix)

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