Project description:Human brown fat tumors (hibernomas) display concomitant loss of the tumor suppressor genes MEN1 and AIP. In the present study, we hypothesized that the brown fat phenotype is attributed to these mutations. Accordingly, we demonstrate that silencing of AIP in human brown preadipocytic and white fat cell lines results in the induction of the brown fat marker UCP1. In human adipocytic tumors, loss of MEN1 was found both in white (one out of 51 lipomas) and brown fat tumors. In contrast, concurrent loss of AIP was always accompanied by a brown fat morphology. We conclude that this white-to-brown phenotype switch in brown fat tumors is mediated by the loss of AIP.
Project description:Hibernomas are benign tumors with morphological features resembling brown fat. They consistently display cytogenetic rearrangements, typically translocations, involving chromosome band 11q13. Here we demonstrate that these aberrations are associated with concomitant deletions of AIP and MEN1, tumor suppressor genes that are located 3 Mb apart and that underlie the hereditary syndromes pituitary adenoma predisposition and multiple endocrine neoplasia type I. MEN1 and AIP displayed a low expression in hibernomas whereas the expression of genes up-regulated in brown fat-PPARA, PPARG, PPARGC1A, and UCP1-was high. Thus, loss of MEN1 and AIP is likely to be pathogenetically essential for hibernoma development. Simultaneous loss of two tumor suppressor genes has not previously been shown to result from a neoplasia-associated translocation. Furthermore, in contrast to the prevailing assumption that benign tumors harbor relatively few genetic aberrations, the present analyses demonstrate that a considerable number of chromosome breaks are involved in the pathogenesis of hibernoma. Global copy number analysis was performed using single nucleotide polymorphism (SNP) array. Cases 1-14 were hybridized onto Illumina Human1M-Duo v3.0 (and Human CNV370-Quad v3.0) BeadChip (Illumina, San Diego, CA, USA), following standard protocols supplied by the manufacturer. Case 15 was analyzed using Illumina Human Omni-Quad BeadChip. Normal blood DNA was analyzed in cases 1, 2, 4 and 6 using the Human CNV370-Quad v3.0 BeadChip. Data analysis was done using the BeadStudio software (Illumina).
Project description:Hibernomas are benign tumors with morphological features resembling brown fat. They consistently display cytogenetic rearrangements, typically translocations, involving chromosome band 11q13. Here we demonstrate that these aberrations are associated with concomitant deletions of AIP and MEN1, tumor suppressor genes that are located 3 Mb apart and that underlie the hereditary syndromes pituitary adenoma predisposition and multiple endocrine neoplasia type I. MEN1 and AIP displayed a low expression in hibernomas whereas the expression of genes up-regulated in brown fat-PPARA, PPARG, PPARGC1A, and UCP1-was high. Thus, loss of MEN1 and AIP is likely to be pathogenetically essential for hibernoma development. Simultaneous loss of two tumor suppressor genes has not previously been shown to result from a neoplasia-associated translocation. Furthermore, in contrast to the prevailing assumption that benign tumors harbor relatively few genetic aberrations, the present analyses demonstrate that a considerable number of chromosome breaks are involved in the pathogenesis of hibernoma.
Project description:Enhancing brown fat activity and promoting white fat browning are attractive therapeutic strategies for obesity and its associated metabolic disorders. To provide a comprehensive picture of the regulatory network in these processes, we conducted a series of transcriptome studies by RNA-seq and quantified the mRNA and lncRNA changes during white fat browning induced by chronic cold exposure, beta-adrenergic agonist and intensive exercises, brown fat activation by acute cold exposure and inactivation by thermoneutrality.
Project description:Activation and recruitment of thermogenic cells in human white adipose tissues (“browning”) can counteract obesity and associated metabolic disorders. However, quantifying the effects of therapeutic interventions on browning remains enigmatic. Here, we devise a computational approach, profiling of fat tissue types (ProFAT), for the quantification of thermogenic potential of heterogeneous fat biopsies based on the prediction of white and brown adipocytes content from raw gene expression profiles. ProFat systematically integrates 103 mouse fat-derived transcriptomes to identify unbiased and robust gene signatures of brown and white adipocytes. Application of ProFAT to 80 mouse and 97 human transcriptional profiles from 14 independent studies correctly predicts browning capacity upon various physiological and pharmacological stimuli. Our study represents the most exhaustive comparative analysis of public data on adipose biology towards quantification of browning after personalized medical intervention. ProFat is freely available and should become increasingly powerful with the growing wealth of transcriptomics data.
Project description:Brown adipose tissue (BAT) is a central thermogenic organ that enhances energy expenditure (EE) and cardiometabolic health. However, regulators that specifically increase the number of thermogenic adipocytes are still an unmet need. Here, we show by phosphoproteomics that cAMP activates distinct signaling pathways in brown progenitors, with the cAMP-EPAC1 axis enhancing proliferation and differentiation of thermogenic but not white adipocytes. Further analysis revealed that a specific subpopulation of preadipocytes that are PDGFRα-positive express EPAC1. In vivo, pharmacological activation of EPAC1 enhances BAT growth and browning of white fat, leading to increased EE and reduced diet-induced adiposity. In contrast, mice lacking EPAC1 in PDGFRα-positive preadipocytes show the opposite phenotype. Importantly, EPAC1 activation enhances proliferation and differentiation of human brown adipocytes and human brown fat organoids. Interestingly, a coding variant in EPAC1 that positively correlates with BMI abolishes norepinephrine-induced proliferation of brown adipocytes. Thus, EPAC1 might be an attractive target to enhance thermogenic adipocyte number and EE to combat metabolic diseases.
Project description:Analysis of subcutaneous adipose tissue (IWAT) from Yin Yang 1 brown fat specific knockout mice fed a high fat diet for 2 weeks. The goal was to identify a gene signature of IWAT browning in YY1 mutant mice. Control mice YY1flox/flox versus YY1flox/flox; Ucp1Cre were fed a high fat diet for 2 weeks
Project description:Brown adipose tissue (BAT) thermogenesis and the browning of white adipose tissue are important components of energy expenditure. An RNAseq-based analysis of the mouse BAT transcriptome led us to identify GPR120 as a gene induced by thermogenic activation. GPR120, a G protein-coupled receptor binding unsaturated long-chain fatty acids, is known to mediate some beneficial metabolic actions of polyunsaturated fatty acids. We show that pharmacological activation of GPR120 induces BAT activity and promotes the browning of white fat in mice, whereas GRP120-null mice show impaired browning in response to cold. n-3 polyunsaturated fatty acids induce brown and beige adipocyte differentiation and thermogenic activation, and these effects require GPR120. GPR120 activation induces the release of fibroblast growth factor-21 (FGF-21) by brown and beige adipocytes and increases blood FGF21 levels. The effects of GPR120 activation are impaired in FGF21-null mice and cells. Thus, the lipid sensor GPR120 constitutes a novel pathway of brown fat activation and involves FGF21.
Project description:Analysis of subcutaneous adipose tissue (IWAT) from Yin Yang 1 brown fat specific knockout mice fed a high fat diet for 2 weeks. The goal was to identify a gene signature of IWAT browning in YY1 mutant mice.