Project description:Histone H3K4me1/2 methyltransferases MLL3/MLL4 and H3K27 acetyltransferases CBP/p300 are major enhancer epigenomic writers. To understand how these epigenomic writers orchestrate enhancer landscapes during cell differentiation, we have profiled genomic binding of MLL4, CBP, lineage-determining transcription factors, as well as transcriptome and epigenome during adipogenesis of immortalized preadipocytes derived from mouse brown adipose tissue (BAT). We show that MLL4 and CBP drive the dynamic enhancer epigenome, which correlates with the dynamic transcriptome. MLL3/MLL4 are required for CBP/p300 binding on enhancers activated during adipogenesis. Further, we show that MLL4 and CBP identify super-enhancers of adipogenesis and that MLL3/MLL4 are required for the formation of super-enhancers. Finally, in brown adipocytes differentiated in culture, MLL4 identifies primed super-enhancers of genes fully activated in BAT such as the thermogenic Ucp1. Comparison of MLL4-defined super-enhancers in brown and white adipogenesis predicted a list of brown-specific super-enhancers SEs associated genes that are likely to be important to BAT functions. These results establish MLL3/MLL4 and CBP/p300 as master enhancer epigenomic writers and suggest that enhancer-priming by MLL3/MLL4 followed by enhancer-activation by CBP/p300 sequentially shape dynamic enhancer landscapes during cell differentiation. Our data also provide a rich resource for understanding epigenomic regulation of brown adipogenesis.
Project description:We depicted a genome-wide integrative view of DNA methylome by reduced representation bisulfite sequencing (RRBS) and transcriptome by RNA-seq during brown and white adipocyte differentiation. Our analysis demonstrated that DNA methylation is a stable epigenetic signature for brown and white cell lineage before, during and after differentiation. When comparing white to brown adipocytes at all three time points of differentiation, we identified five members of the Hox family whose expression levels were anti-correlated with promoter methylation, suggesting a regulatory role of DNA methylation in transcription.
Project description:We depicted a genome-wide integrative view of DNA methylome by reduced representation bisulfite sequencing (RRBS) and transcriptome by RNA-seq during brown and white adipocyte differentiation. Our analysis demonstrated that DNA methylation is a stable epigenetic signature for brown and white cell lineage before, during and after differentiation. When comparing white to brown adipocytes at all three time points of differentiation, we identified five members of the Hox family whose expression levels were anti-correlated with promoter methylation, suggesting a regulatory role of DNA methylation in transcription.
Project description:To systemically determine the translational control of gene expression in adipose, we performed ribosome profiling and RNA-seq in parallel to depict the translatome and transcriptome changes during primary brown and white adipogenesis, and between brown and white adipose tissue.
Project description:Secreted proteins from adipose tissue play a role in metabolic cross-talk and homeostasis. We performed high sensitivity mass spectrometry-based proteomics on the cell media of human adipocytes derived from the supraclavicular brown adipose and from the subcutaneous white adipose depots of adult humans. We identified 471 potentially secreted proteins covering interesting protein categories such as hormones, growth factors, extracellular matrix proteins and proteins of the complement system, which were differentially regulated in brown and white adipocytes. A total of 101 proteins were exclusively quantified in brown adipocytes and among these were ependymin-related protein 1 (EPDR1). Functional studies suggested a role for EPDR1 in thermogenic adipogenesis. In conclusion, we report substantial differences between the secretomes of brown and white human adipocytes and identify novel candidate batokines that can be important regulators of metabolism.
Project description: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. 3 samples of pre adipocytes isolated from brown adipose tissue examined pre and post differentiation to brown adipocytes. 3 samples of pre-adipocytes isolated from white adipose tissue and examined pre and post differentiation to adipocytes.
Project description:Attainment of a brown adipocyte cell phenotype in white adipocytes, with their abundant mitochondria and increased energy expenditure potential, is a legitimate strategy for combating obesity. The unique transcriptional regulators of the primary brown adipocyte phenotype are unknown, limiting our ability to promote brown adipogenesis over white. In the present work, we used microarray analysis strategies to study primary preadipocytes, and we made the striking discovery that brown preadipocytes demonstrate a myogenic transcriptional signature, whereas both brown and white primary preadipocytes demonstrate signatures distinct from those found in immortalized adipogenic models. We found a plausible SIRT1-related transcriptional signature during brown adipocyte differentiation that may contribute to silencing the myogenic signature. In contrast to brown preadipocytes or skeletal muscle cells, white preadipocytes express Tcf21, a transcription factor that has been shown to suppress myogenesis and nuclear receptor activity. In addition, we identified a number of developmental genes that are differentially expressed between brown and white preadipocytes and that have recently been implicated in human obesity. The interlinkage between the myocyte and the brown preadipocyte confirms the distinct origin for brown versus white adipose tissue and also represents a plausible explanation as to why brown adipocytes ultimately specialize in lipid catabolism rather than storage, much like oxidative skeletal muscle tissue. Keywords: In vitro differentiation
Project description:Attainment of a brown adipocyte cell phenotype in white adipocytes, with their abundant mitochondria and increased energy expenditure potential, is a legitimate strategy for combating obesity. The unique transcriptional regulators of the primary brown adipocyte phenotype are unknown, limiting our ability to promote brown adipogenesis over white. In the present work, we used microarray analysis strategies to study primary preadipocytes, and we made the striking discovery that brown preadipocytes demonstrate a myogenic transcriptional signature, whereas both brown and white primary preadipocytes demonstrate signatures distinct from those found in immortalized adipogenic models. We found a plausible SIRT1-related transcriptional signature during brown adipocyte differentiation that may contribute to silencing the myogenic signature. In contrast to brown preadipocytes or skeletal muscle cells, white preadipocytes express Tcf21, a transcription factor that has been shown to suppress myogenesis and nuclear receptor activity. In addition, we identified a number of developmental genes that are differentially expressed between brown and white preadipocytes and that have recently been implicated in human obesity. The interlinkage between the myocyte and the brown preadipocyte confirms the distinct origin for brown versus white adipose tissue and also represents a plausible explanation as to why brown adipocytes ultimately specialize in lipid catabolism rather than storage, much like oxidative skeletal muscle tissue. Experiment Overall Design: Comparisons of white and brown pre- and mature-adiposytes