Integrated approach to the study of human adipocyte differentiation (original) (raw)
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Endocrinology
Context Healthy hyperplasic (many but smaller fat cells) white adipose tissue (WAT) expansion is mediated by recruitment, proliferation and/or differentiation of new fat cells. This process (adipogenesis) is controlled by transcriptional programs that have been mostly identified in rodents. Objective A systemic investigation of adipogenic human transcription factors (TFs) that are relevant for metabolic conditions has not been revealed previously. Methods TFs regulated in WAT by obesity, adipose morphology, cancer cachexia, and insulin resistance were selected from microarrays. Their role in differentiation of human adipose tissue-derived stem cells (hASC) was investigated by RNA interference (RNAi) screen. Lipid accumulation, cell number, and lipolysis were measured for all screened factors (148 TFs). RNA (RNAseq), protein (Western blot) expression, insulin, and catecholamine responsiveness were examined in hASC following siRNA treatment of selected target TFs. Results Analysis of ...
Clinical evidence shows that visceral fat accumulation decreases whereas sc fat increases in patients treated with thiazolidinediones (TZDs), a type of peroxisome proliferator-activated receptor (PPAR) agonist. To clarify the molecular mechanism of the differential effects of PPAR agonists on sc and visceral adipose, we investigated expression profiling of PPAR-regulated micro-RNAs (miRNAs) using miRNA microarray. The level of 182 miRNAs changed in human sc adipose treated with pioglitazone, whereas only 46 miRNAs changed in visceral adipose. Among these miRNAs, 27 miRNAs changed in both human sc and visceral adipocytes. Specifically, 7 miRNAs changed at the same direction in sc and visceral adipocytes, whereas 20 miRNAs changed at opposite directions in these two fat depots. Bioinformatics analysis showed that these miRNAs and the predicted target genes were involved in TGF-, Wnt/-catenin-, and insulin-signaling pathways and related to metabolic regulation or cell cycle. Among the miRNAs changed at the same direction in sc and visceral adipocytes, miR-378, located in the first intron of PPAR coactivator 1 (PGC1), was coordinately expressed with PGC1 during adipogenesis. Moreover, miR-378 and PGC1 were both up-regulated by PPAR agonist. We also provided evidence that miR-378 promoted adipogenesis in sc fat, but not in visceral fat. These results display miRNAs expression profiling altered in sc and visceral adipogenesis regulated by PPAR and suggest a potential mechanism underlying the differential effects of TZDs on the 2 fat depot accumulations. (Endocrinology 155: 2155–2165, 2014)
Nucleic Acids Research, 2012
Peroxisome proliferator-activated receptor c (PPARc) is a key transcription factor in mammalian adipogenesis. Genome-wide approaches have identified thousands of PPARc binding sites in mouse adipocytes and PPARc upregulates hundreds of protein-coding genes during adipogenesis. However, no microRNA (miRNA) genes have been identified as primary PPARc-targets. By integration of four separate datasets of genomewide PPARc binding sites in 3T3-L1 adipocytes we identified 98 miRNA clusters with PPARc binding within 50 kb from miRNA transcription start sites. Nineteen mature miRNAs were upregulated !2-fold during adipogenesis and for six of these miRNA loci the PPARc binding sites were confirmed by at least three datasets. The upregulation of five miRNA genes miR-103-1 (host gene Pank3), miR-148b (Copz1), miR-182/96/183, miR-205 and miR-378 (Ppargc1b) followed that of Pparg. The PPARcdependence of four of these miRNA loci was demonstrated by PPARc knock-down and the loci of miR-103-1 (Pank3), miR-205 and miR-378 (Ppargc1b) were also responsive to the PPARc ligand rosiglitazone. Finally, chromatin immunoprecipitation analysis validated in silico predicted PPARc binding sites at all three loci and H3K27 acetylation was analyzed to confirm the activity of these enhancers. In conclusion, we identified 22 putative PPARc target miRNA genes, showed the PPARc dependence of four of these genes and demonstrated three as direct PPARc target genes in mouse adipogenesis.
BMC Medical Genomics, 2010
BackgroundObesity results from an imbalance between food intake and energy expenditure, which leads to an excess of adipose tissue. The excess of adipose tissue and adipocyte dysfunction associated with obesity are linked to the abnormal regulation of adipogenesis. The objective of this study was to analyze the expression profile of cell-cycle- and lipid-metabolism-related genes of adipose tissue in morbid obesity.MethodsWe used a custom-made focused cDNA microarray to determine the adipose tissue mRNA expression profile. Gene expression of subcutaneous abdominal fat samples from 15 morbidly obese women was compared with subcutaneous fat samples from 10 nonobese control patients. The findings were validated in an independent population of 31 obese women and 9 obese men and in an animal model of obesity (Lepob/obmice) by real-time RT-PCR.ResultsMicroarray analysis revealed that transcription factors that regulate the first stages of adipocyte differentiation, such as CCAAT/enhancer b...
Gene-chip studies of adipogenesis-regulated microRNAs in mouse primary adipocytes and human obesity
BMC Endocrine Disorders, 2011
Background: Adipose tissue abundance relies partly on the factors that regulate adipogenesis, i.e. proliferation and differentiation of adipocytes. While components of the transcriptional program that initiates adipogenesis is wellknown, 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. Methods: Several models exist to study adipogenesis in vitro, of which the cell line 3T3-L1 is the most well known, albeit not the most physiologically appropriate. Thus, as an alternative, we produced EXIQON microarray of brown and white primary murine adipocytes (prior to and following differentiation) to yield global profiles of miRNAs.
Novel Insights into Adipogenesis from Omics Data
Obesity, the excess accumulation of adipose tissue, is one of the most pressing health problems in both the Western world and in developing countries. Adipose tissue growth results from two processes: the increase in number of adipocytes (hyperplasia) that develop from precursor cells, and the growth of individual fat cells (hypertrophy) due to incorporation of triglycerides. Adipogenesis, the process of fat cell development, has been extensively studied using various cell and animal models. While these studies pointed out a number of key factors involved in adipogenesis, the list of molecular components is far from complete. The advance of high-throughput technologies has sparked many experimental studies aimed at the identification of novel molecular components regulating adipogenesis. This paper examines the results of recent studies on adipogenesis using high-throughput technologies. Specifically, it provides an overview of studies employing microarrays for gene expression profiling and studies using gel based and non-gel based proteomics as well as a chromatin immunoprecipitation followed by microarray analysis (ChIP-chip) or sequencing (ChIP-seq). Due to the maturity of the technology, the bulk of the available data was generated using microarrays. Therefore these data sets were not only reviewed but also underwent meta analysis. The review also shows that large-scale omics technologies in conjunction with sophisticated bioinformatics analyses can provide not only a list of novel players, but also a global view on biological processes and molecular networks. Finally,developing technologies and computational challenges associated with the data analyses are highlighted, and an outlook on the questions not previously addressed is provided.
Scientific data, 2017
Obesity affects gene expression and metabolism of white adipose tissue (WAT), which results in insulin resistance (IR) and type 2 diabetes. However, WAT is a heterogeneous organ containing many cell types that might respond differently to obesity-induced changes. We performed flow cytometry sorting and RNA expression profiling by microarray of major WAT cell types (adipocytes, CD45-/CD31-/CD34+ progenitors, CD45+/CD14+ monocytes/ macrophages, CD45+/CD14- leukocytes), which allowed us to identify genes enriched in specific cell fractions. Additionally, we included adipocytes and adipocyte progenitor cells obtained from lean and obese individuals. Taken together, we provide a detailed gene expression atlas of major human adipose tissue resident cell types for clinical/basic research and using this dataset provide lists of cell-type specific genes that are of interest for metabolic research.
Understanding Adipocyte Differentiation
Physiological Reviews, 1998
Gregoire, Francine M., Cynthia M. Smas, and Hei Sook Sul. Understanding Adipocyte Differentiation. Physiol. Rev. 78: 783–809, 1998. — The adipocyte plays a critical role in energy balance. Adipose tissue growth involves an increase in adipocyte size and the formation of new adipocytes from precursor cells. For the last 20 years, the cellular and molecular mechanisms of adipocyte differentiation have been extensively studied using preadipocyte culture systems. Committed preadipocytes undergo growth arrest and subsequent terminal differentiation into adipocytes. This is accompanied by a dramatic increase in expression of adipocyte genes including adipocyte fatty acid binding protein and lipid-metabolizing enzymes. Characterization of regulatory regions of adipose-specific genes has led to the identification of the transcription factors peroxisome proliferator-activated receptor-γ (PPAR-γ) and CCAAT/enhancer binding protein (C/EBP), which play a key role in the complex transcriptional ...
BMC Endocrine Disorders
Objective A better understanding of mechanisms regulating lipogenesis and adipogenesis is needed to overcome the obesity pandemic. We aimed to study the relationship of the transcript levels of peroxisome proliferator activator receptor γ (PPARγ), CCAAT/enhancer-binding protein alpha (C/EBP-α), liver X receptor (LXR), sterol regulatory element-binding protein-1c (SREBP-1c), fatty acid synthase (FAS), and acetyl-CoA carboxylase (ACC) in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) from obese and normal-weight women with a variety of anthropometric indices, metabolic and biochemical parameters, and insulin resistance. Methods Real‐time PCR was done to evaluate the transcript levels of the above‐mentioned genes in VAT and SAT from all participants. Results Using principal component analysis (PCA) results, two significant principal components were identified for adipogenic and lipogenic genes in SAT (SPC1 and SPC2) and VAT (VPC1 and VPC2). SPC1 was characterized b...
Nutrients
Disturbances in adipose tissue significantly contribute to the development of metabolic disorders, which are connected with hyperglycemia (HG) and underlain by epigenetics-based mechanisms. Therefore, we aimed to evaluate the effect of hyperglycemia on proliferating, differentiating and maturating human visceral pre/adipocytes (HPA-v). Three stages of cell culture were conducted under constant or variable glycemic conditions. Adipogenesis progress was assessed using BODIPY 505/515 staining. Lipid content typical for normal and hyperglycemic conditions of adipocytes was analyzed using Raman spectroscopy and imaging. Expression of adipogenic markers, PPARγ and C/EBPα, was determined at the mRNA and protein levels. We also examined expression of miRNAs proven to target PPARγ (miR-34a-5p) and C/EBPα (miR-137-3p), employing TaqMan Low-Density Arrays (TLDA) cards. Hyperglycemia altered morphology of differentiating HPA-v in relation to normoglycemia by accelerating the formation of lipid ...