Project description:Obesity is associated with insulin resistance and type 2 diabetes, implying a role for adipose tissue in the etiology of these disorders. We used cDNA microarrays to obtain expression profiles of adipocyte by the treatment of insulin and anti-diabetic drug rosiglitazone at both high and low glucose level. Mouse 3T3-L1 mature adipocytes were treated 2 days 1) with or without 1 µM insulin at low and high glucose level, 2) with or without 0.5 μM rosiglitazone at low and high glucose and insulin level. 1) The comparison between the insulin and non-insulin treatment at the same glucose level showed minor changes in the transcriptome. The expressions of some processing enzymes for extracellular matrix components were regulated by insulin. 2) Transcriptome data indicates that an altered energy metabolism is induced by rosiglitazone in mature adipocytes. In addition, rosiglitazone represses adipokine expression, except adiponectin and ApoE. Moreover, transcriptome changes indicate that a general repression of secreted protein encoding genes occurs. Keywords: homone and drug response
Project description:Background. Obesity and body fat distribution are important risk factors for the development of type 2 diabetes and metabolic syndrome. Evidence has accumulated that this risk is related to intrinsic differences in behavior of adipocytes in different fat depots. LIM Domain Only 3 (LMO3) plays a crucial role in adipogenesis modulating the key adipogenic master switch PPARγ in human, but not mouse, visceral adipose progenitors; however, despite high expression in mature adipocytes, its function in these cells is currently unknown. Aims/Hypothesis. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Methods. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain- or loss of LMO3 expression, respectively.Results. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. Lmo3 expression in eWAT significantly improved glucose clearance and insulin sensitivity in diet-induced obesity, paralleled by increased serum adiponectin. In vitro, Lmo3 expression in 3T3-L1 adipocytes increased insulin-stimulated GLUT4 translocation and glucose uptake as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. On a molecular level, LMO3 augmented PPARg activity, oxidative mitochondrial gene expression, which depended on and the expression of the PPARg co-activator Ncoa1, which was required for LMO3 effects on mitochondria and glucose uptake. In human mature adipocytes, LMO3 overexpression promoted, while silencing of LMO3 suppressed mitochondrial oxidative capacity. Conclusions. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose tolerance, insulin sensitivity and adiponectin secretion. Together with increased PPARγ activity, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity.
Project description:Aims/Hypothesis. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Methods. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain- or loss of LMO3 expression, respectively. Results. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. Lmo3 expression in eWAT significantly improved glucose clearance and insulin sensitivity in diet-induced obesity, paralleled by increased serum adiponectin. On a molecular level, LMO3 expression in eWAT increased pathways indicative of adipogenesis and PPARg signaling as well as mitochondrial activity, paralleled by a suppression of adipose tissue fibrosis. In vitro, Lmo3 expression in 3T3-L1 adipocytes increased insulin-stimulated GLUT4 translocation and glucose uptake as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. LMO3 overexpression promoted, while silencing of LMO3 suppressed, mitochondrial oxidative capacity in human mature adipocytes. Conclusions. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose tolerance, insulin sensitivity and adiponectin secretion. Together with increased PPARγ activity, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity.
Project description:Aims/Hypothesis. The aim of this study was to determine the potential involvement of LMO3-dependent pathways in the modulation of key functions of mature adipocytes during obesity. Methods. Based on a recently engineered hybrid rAAV serotype Rec2 shown to efficiently transduce both brown adipose tissue (BAT) and white adipose tissue (WAT), we delivered YFP or Lmo3 to epididymal WAT (eWAT) of C57Bl6/J mice on a high fat diet (HFD). The effects of eWAT transduction on metabolic parameters were evaluated 10 weeks later. To further define the role of LMO3 in insulin-stimulated glucose uptake, insulin signaling, adipocyte bioenergetics as well as endocrine function, experiments were conducted in 3T3-L1 adipocytes and newly differentiated human primary mature adipocytes, engineered for transient gain- or loss of LMO3 expression, respectively. Results. AAV transduction of eWAT results in strong and stable Lmo3 expression specifically in the adipocyte fraction over a course of 10 weeks with HFD feeding. Lmo3 expression in eWAT significantly improved glucose clearance and insulin sensitivity in diet-induced obesity, paralleled by increased serum adiponectin. On a molecular level, LMO3 expression in eWAT increased pathways indicative of adipogenesis and PPARg signaling as well as mitochondrial activity, paralleled by a suppression of adipose tissue fibrosis. In vitro, Lmo3 expression in 3T3-L1 adipocytes increased insulin-stimulated GLUT4 translocation and glucose uptake as well as mitochondrial oxidative capacity in addition to fatty acid oxidation. LMO3 overexpression promoted, while silencing of LMO3 suppressed, mitochondrial oxidative capacity in human mature adipocytes. Conclusions. LMO3 expression in visceral adipose tissue regulates multiple genes that preserve adipose tissue functionality during obesity, such as glucose tolerance, insulin sensitivity and adiponectin secretion. Together with increased PPARγ activity, these gene expression changes promote insulin-induced GLUT4 translocation, glucose uptake in addition to increased mitochondrial oxidative capacity, limiting HFD-induced adipose dysfunction. These data add LMO3 as a novel regulator improving visceral adipose tissue function during obesity.
Project description:Growing evidence indicates that PPARγ agonists, such as rosiglitazone (RSG,), induce adipose mitochondrial biogenesis. Using microarrays, we systematically analyzed nucleus-encoded mitochondrial gene expression in two common murine adipocyte models, 3T3 L1 and C3H/10T1/2 adipocytes, and aimed to further establish the direct role of RSG, and capture the temporal changes in mitochondrial gene transcription during this process. Experiment Overall Design: Fully differentiated 3T3 L1 and C3H/10T1/2 adipocytes were treated with RSG, or DMSO vehicle for 1, 2, 4, 7, 24, and 48 hrs, and total RNA was extracted for microarray analysis.
Project description:Insulin-stimulated glucose uptake is known to involve microtubules, although the function of microtubules and the microtubule-regulating proteins involved in insulin action are poorly understood. CLASP2, a plus-end tracking microtubule-associated protein (+TIP) that controls microtubule dynamics, was recently implicated as the first +TIP associated with insulin-regulated glucose uptake. Here, using protein-specific targeted quantitative phosphoproteomics within 3T3-L1 adipocytes, we discovered that insulin regulates phosphorylation of the CLASP2 network members G2L1, MARK2, CLIP2, AGAP3 and CKAP5 as well as EB1, revealing the existence of a previously unknown microtubule-associated protein system that responds to insulin. To further investigate, G2L1 interactome studies within 3T3-L1 adipocytes revealed that G2L1 co-immunoprecipitates CLASP2 and CLIP2 as well as the master integrators of +TIP assembly, the end binding (EB) proteins. Live-cell total internal reflection fluorescence microscopy in adipocytes revealed G2L1 and CLASP2 colocalize on microtubule plus-ends. We found that while insulin increases the number of CLASP2-containing plus-ends, insulin treatment simultaneously decreases CLASP2-containing plus-end velocity. In addition, we discovered that insulin stimulates re-distribution of CLASP2 and G2L1 from exclusive plus-end tracking to “trailing” behind the growing tip of the microtubule. Insulin treatment increases -tubulin Lysine 40 acetylation, a mechanism that was observed to be regulated by a counterbalance between GSK3 and mTOR, and also led to microtubule stabilization. Our studies introduce insulin-stimulated microtubule stabilization and plus-end trailing of +TIPs as new modes of insulin action and reveal the likelihood that a network of microtubule-associated proteins synergize to coordinate insulin-regulated microtubule dynamics.
Project description:Insulin action in adipocytes affects whole-body insulin sensitivity. Studies of adipose-specific Glut4 knockout mice have established that adipose Glut4 contributes to the control of systemic glucose homeostasis. Presumably, this reflects a role for Glut4-mediated glucose transport in the regulation of secreted adipokines. In cultured 3T3-L1 adipocytes, Rab10 GTPase is required for insulin-stimulated translocation of Glut4 (Sano et al., 2007). The physiological importance of adipose Rab10 and the significance of its role in the control of Glut4 vesicle trafficking in vivo are unknown. Here we report that adipocytes from adipose-specific Rab10 knockout mice have a ~50% reduction in glucose uptake and Glut4 translocation to the cell surface in response to insulin, demonstrating a role for Rab10 in Glut4 trafficking. Moreover, hyperinsulinemic-euglycemic clamp shows decreased whole-body glucose uptake as well as impaired suppression of hepatic glucose production in adipose Rab10 knockout mice. Thus, fully functional Glut4 vesicle trafficking in adipocytes is critical for maintaining insulin sensitivity. Comparative transcriptome analysis of perigonadal adipose tissue demonstrates significant transcriptional similarities between adipose Rab10 knockout mice and adipose Glut4 knockout mice, consistent with the notion that the phenotypic similarities between the two models are mediated by reduced insulin-stimulated glucose transport into adipocytes. Transcriptome sequencing of perigonadal white adipose tissue
Project description:Insulin is a potent regulator of protein metabolism. Here we describe a time-resolved map of insulin-regulated protein turnover in 3T3-L1 adipocytes using metabolic pulse-chase labelling and high-resolution mass spectrometry.
Project description:PPARM-NM-3 is a master transcriptional regulator of adipogenesis. Hence, the identification of PPARM-NM-3 coactivators should help reveal mechanisms controlling gene expression in adipose tissue development and physiology. We show that the non-coding RNA Steroid receptor RNA Activator, SRA, associates with PPARM-NM-3 and coactivates PPARM-NM-3-dependent reporter gene expression. Overexpression of SRA in ST2 adipocyte precursor cells promotes their differentiation into adipocytes. Conversely, knockdown of endogenous SRA inhibits 3T3-L1 preadipocyte differentiation. Microarray analysis reveals hundreds of SRA-responsive genes in adipocytes, including genes in cell cycle, insulin and TNFM-NM-1 signaling pathways. Some functions of SRA may involve mechanisms other than coactivation of PPARM-NM-3. SRA increases insulin-stimulated glucose uptake in adipocytes. SRA promotes S-phase entry during mitotic clonal expansion, decreases expression of cyclin-dependent kinase inhibiters p21Cip1 and p27Kip1, and increases phosphorylation of Cdk1/Cdc2. SRA also inhibits the TNFM-NM-1-induced phosphorylation of c-Jun NH2-terminal kinase. In conclusion, SRA enhances adipogenesis and adipocyte function through multiple pathways. Total RNA was isolated from fully differentiated (MDIT day 4) SRA overexpressing (pMSCV-SRA) and control (pMSCV empty vector) ST2 adipocytes, or fully differentiated (MDIT day 8) shSRA knockdown (pSuperior-shSRA) or shControl (pSuperior-shcontrol) 3T3-L1 adipocytes. Genome wide gene expression analysis was performed using Affymetrix mouse genome 430 2.0 arrays. Triplicate samples were analyzed.