Nck2 Regulates Adiposity and Adiposity-Related Metabolic Disorders in Mice and Human
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ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Marie-Anne Goyette
PROVIDER: E-GEOD-63510 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Obesity is linked to the development of metabolic disorders. Expansion of white adipose tissue (WAT) from hypertrophy of pre-existing adipocytes and/or differentiation of precursors into new mature adipocytes contributes to obesity. We found that Nck2 expression is largely restricted to WAT, raising the hypothesis that it may play a unique function in that tissue. Using mice lacking Nck2, we found that Nck2 regulates adipocyte hypertrophy thus contributing to increased adiposity and progressive glucose intolerance, insulin resistance and hepatic steatosis. These findings were recapitulated in humans such that Nck2 expression in omental WAT was inversely correlated with the degree of obesity. Mechanistically, Nck2 deficiency promoted the induction of an adipocyte differentiation program and signaling by the PERK-eIF2α-ATF4 pathway in agreement with a role for the unfolded protein response in adipogenesis. These findings uncover Nck2 as a novel regulator of adipogenesis and that perturbation in its functionality contributes to adiposity-related metabolic disorders.
2016-07-01 | GSE63510 | GEO
Project description:White adipose tissue (WAT) is a key regulator of systemic energy metabolism, and impaired WAT plasticity characterized by enlargement of preexisting adipocytes associates with WAT dysfunction, obesity and metabolic complications. However, the mechanisms that retain proper adipose tissue plasticity required for metabolic fitness are unclear. Here, we comprehensively showed that adipocyte-specific DNA methylation, manifested in enhancers and CTCF sites, directs distal enhancer-mediated transcriptomic features required to conserve metabolic functions of white adipocytes. Particularly, genetic ablation of adipocyte Dnmt1, the major methylation writer, led to increased adiposity characterized by increased adipocyte hypertrophy along with reduced expansion of adipocyte precursors (APs). These effects of Dnmt1 deficiency provoked systemic hyperlipidemia and impaired energy metabolism both in lean and obese mice. Mechanistically, Dnmt1 deficiency abrogated mitochondrial bioenergetics by inhibiting mitochondrial fission and promoted aberrant lipid metabolism in adipocytes, rendering adipocyte hypertrophy and WAT dysfunction. Dnmt1-dependent DNA methylation prevented aberrant CTCF binding and, in turn, sustained the proper chromosome architecture to permit interactions between enhancer and dynamin-related protein gene Drp1 in adipocytes. Also, adipose DNMT1 expression inversely correlated with adiposity and markers of metabolic health, but positively correlated with AP-specific markers in obese human subjects. Thus, these findings support strategies utilizing Dnmt1 action on mitochondrial bioenergetics in adipocytes to combat obesity and related metabolic pathology.
2021-03-24 | GSE158944 | GEO
Project description:Obesity is a pandemic health problem with poor solutions, especially for targeted treatment. Here we develop a polycation-based nanomedicine to selectively target visceral adiposity, the more metabolically detrimental and manipulation-resistant fat. We demonstrated that the polycationic polymer polyamidoamine (PAMAM) generation 3 (P-G3) was specifically enriched in the visceral fat due to its high charge density when delivered intraperitoneally. Moreover, P-G3 treatment of obese mice inhibited visceral adiposity, increased energy expenditure, prevented obesity, and alleviated the associated metabolic dysfunctions. In vitro adipogenesis models and single-cell RNA sequencing (scRNA-seq) revealed that P-G3 paradoxically uncouples the defining function of adipocyte - lipid synthesis and storage - from adipocyte development to create unique “dwarf” adipocytes that possess normal adipocyte functions but are deficient in hypertrophic growth at least through synergistically modulating NAD and mTOR pathways. The visceral fat distribution of P-G3 was further enhanced by modifying P-G3 with cholesterol to form lipophilic nanoparticles, which were also effective in treating obesity. Our study highlights an unexpected strategy to tackle visceral adiposity and champions a new direction of exploring cationic nanomaterials for treating metabolic diseases.
2022-09-19 | GSE209819 | GEO
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.
2021-02-26 | GSE148699 | GEO
Project description:Obesity has become a global health problem. Brown adipose tissue (BAT), specialized for energy expenditure through thermogenesis, potently counteracts obesity. Recently, BAT is also identified in human adults. We found that Lgr4 homozygous mutant (Lgr4m/m) mice display reduced adiposity and exhibit brown-like adipocytes in their WAT depots with higher expression of uncoupling protein 1 (Ucp1). Furthermore, Lgr4 ablation potentiates brown adipocyte differentiation from stromal vascular fraction (SVF) of epididymal WAT (eWAT) in vitro. We used microarrays to emxamine the gene expression profiles of the brown-like adipocytes differentiated from SVF of wild-type and Lgr4 mutant mice. We identified distinct gene expression profiles of these two groups. To demonstrate Lgr4 ablation can potentiate the differentiation of SVF from eWAT toward brown-like adipocytes in vitro, we isolated SVF from epididymal white adipose tissue (eWAT) of wild-type (WT) and Lgr4 mutant mice. We then plated SVF cells in 12-well plate, and differentiated them to brown adipocytes, followed by RNA extraction and hybridization with Affymetrix microarrays.
2013-11-07 | E-GEOD-47760 | biostudies-arrayexpress
Project description:Obesity has become a global health problem. Brown adipose tissue (BAT), specialized for energy expenditure through thermogenesis, potently counteracts obesity. Recently, BAT is also identified in human adults. We found that Lgr4 homozygous mutant (Lgr4m/m) mice display reduced adiposity and exhibit brown-like adipocytes in their WAT depots with higher expression of uncoupling protein 1 (Ucp1). Furthermore, Lgr4 ablation potentiates brown adipocyte differentiation from stromal vascular fraction (SVF) of epididymal WAT (eWAT) in vitro. We used microarrays to emxamine the gene expression profiles of the brown-like adipocytes differentiated from SVF of wild-type and Lgr4 mutant mice. We identified distinct gene expression profiles of these two groups.
2013-11-07 | GSE47760 | GEO
Project description:Obesity is an energy balance disorder in which nutrient intake chronically exceeds energy expenditure, resulting in the accumulation of white adipose tissue. Increased adiposity is due to increases in the number and size of adipocytes, which leads to increased body fat and metabolic consequences. Adipocytes induce insulin resistance by promoting lipotoxicity and modulating adipokine secretion. Therefore, a thorough understanding of the mechanisms that regulate adipogenesis could have clinical relevance in preventing and treating obesity and the metabolic syndrome. In this study, we performed miRNA array to measure miRNA profiles of undifferentiated and differentiated 3T3-L1 adipocytes using Agilent(r) miRNA array. We show that miRNA profile changes during adipogenesis. Thus, this data would be useful to find the distinct role of miRNAs for the regulation of adipogenesis.
2013-08-07 | E-MTAB-1783 | biostudies-arrayexpress
Project description:Obesity, and visceral adiposity in particular, increases the risk of common metabolic diseases, including type 2 diabetes, cardiovascular disease, and several forms of cancer. However, the molecular mechanisms responsible for regional fat storage remain poorly characterized, preventing therapeutic innovation. We here applied a systematic genome-wide screen and translational approach, and discovered a novel role for the adipocyte-expressed neutral amino acid transporter SLC7A10/ASC-1 in the regulation of visceral adiposity. Among 65 genes showing both adipose depot-dependent and fat loss-dependent expression, 27 genes further showed significant correlations with waist-to-hip (WHR) ratio adjusted for BMI. Among these ASC-1 was expressed at the highest level in isolated visceral adipocytes. Further, we found decreased ASC-1 mRNA in visceral, and not subcutaneous adipose tissue, in carriers of the KLF14 type 2 diabetes risk allele compared to the protective allele. By profiling amino acid fluxes during adipocyte differentiation in vitro, we found that ASC-1 inhibition by a selective inhibitor decreased adipocyte uptake particularly of serine in mature adipocytes. Interestingly, radiometric amino acid uptake assays showed ASC-1 dependent uptake of the serine D-enantiomere. Using primary human and murine adipocyte models, we uncovered marked effects of inhibiting ASC-1 on mitochondrial respiratory capacity (within hours) and lipid accumulation (within days). Finally, Asc-1 knockout (KO) zebrafish had increased body weight and adipocyte enlargement upon eight-week overfeeding compared to wild-type (WT) fish. RNA sequencing data from zebrafish adipose tissue showed up-regulation of genes involved in fatty acid and lipid metabolism in the ASC-1 KOs, consistent with the increased lipid accumulation in the inhibitor-treated cell models. Additionally, duox, an enzyme involved in ROS generation, showed higher expression in the KOs compared to the WTs. Importantly, we confirmed increased reactive oxygen species (ROS) generation (within minutes and within hours) when inhibiting ASC-1 in our in vitro cell models. Our study points to increased ROS generation and reduced mitochondrial respiratory capacity as central early mechanisms in development of visceral adiposity, and a role for adipocyte D-serine transport via ASC-1 in these processes. Enhancing ASC-1 expression and/or activity in adipocytes, likely through primary effects on one-carbon metabolism and redox balance, is a promising therapeutic strategy for reducing visceral adiposity and related diseases.
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Project description:Lipid mobilization (lipolysis) in white adipose tissue (WAT) critically controls lipid turnover and adiposity in humans. While the acute regulation of lipolysis has been studied in detail, the transcriptional determinants of WAT lipolytic activity remain still largely unexplored. Here we show that the genetic inactivation of transcriptional co-factor transducin beta-like-related (TBLR) 1 blunts the lipolytic response of white adipocytes through the impairment of cAMP-dependent signal transduction. Indeed, mice lacking TBLR1 in adipocytes are defective in fasting-induced lipid mobilization and when placed on a high fat diet show aggravated adiposity, glucose intolerance and insulin resistance. TBLR1 levels are found to increase under lipolytic conditions in WAT of both human patients and mice, correlating with serum free fatty acids (FFA). As a critical regulator of WAT cAMP signaling and lipid mobilization, proper activity of TBLR1 in adipocytes may thus represent a critical molecular checkpoint for the prevention of metabolic dysfunction in subjects with obesity-related disorders. We used microarrays to identify global gene expression in 3T3-L1 adipocytes lacking TBLR1 and compared gene expression to control shRNA treated cells in both basal and isoproterenol stimulated states. We analyzed 12 RNA samples extracted from 3T3-L1 adipocytes that were treated with either control or TBLR1 specific shRNAs and with or without 10 µM isoproterenol for 3 hrs. Three replicates of each condition.
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Project description:The pathogenesis of obesity-related metabolic diseases has been linked to the inflammation of white adipose tissue (WAT), but the molecular interconnections are still not fully understood. MiR-146a controls inflammatory processes by suppressing pro-inflammatory signaling pathways. The aim of this study was to characterize the role of miR-146a in obesity and insulin sensitivityresistance . MiR-146a-/- mice were subjected to a high fat diet followed by metabolic tests and WAT transcriptomics. Gain- and loss-of-function studies were performed using human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes. Compared to controls, miR-146a-/- mice gained significantly more body weight on a high fat diet with increased fat mass and adipocyte hypertrophy. This was accompanied by exacerbated liver steatosis, insulin resistance, and glucose intolerance. Likewise, adipocytes transfected with an inhibitor of miR-146a displayed a decrease in insulin-stimulated glucose uptake, while transfecting miR-146a mimics caused the opposite effect. Natriuretic peptide receptor 3 (NPR3) was identified as a direct target gene of miR-146a in adipocytes and CRISPR/Cas9-mediated knockout of NPR3 increased insulin-stimulated glucose uptake and enhanced de-novo lipogenesis. In summary, miR-146a regulates systemic and adipocyte insulin sensitivity via downregulation of NPR3.
2020-10-12 | GSE151268 | GEO