Mesoderm specific transcript and adipose tissue expansion

中胚层特异性转录和脂肪组织扩张

• 批准号: 9981735
• 负责人: Robert A Koza
• 金额: $ 44.17万
• 依托单位: MAINEHEALTH
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-07-22 至 2022-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9981735
• 关键词: Acyltransferase; Adipocytes; Adipose tissue; Biological Assay; Cell Nucleus; Cells; Complex; Confocal Microscopy; Controlled Environment; DNA; DNA analysis; Data; Development; Diet; Endoplasmic Reticulum; Environment; Epigenetic Process; Epoxide hydrolase; Epoxy Compounds; Fatty acid glycerol esters; Fluorescence Resonance Energy Transfer; Genes; Genetic; Genetic Predisposition to Disease; Genome; Goals; Heritability; High Fat Diet; Homeostasis; Hydrolase; Impairment; In Vitro; Inbreeding; Individual; Inflammation; Knockout Mice; Laboratories; Link; Lipase; Lipids; Liposomes; Mediating; Membrane; Membrane Proteins; Mesenchymal Stem Cells; Mesoderm; Metabolic; Metabolic Diseases; Metabolic dysfunction; Modeling; Modification; Molecular; Mouse Strains; Mus; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathway interactions; Population; Predisposition; Production; Protein Family; Proteins; RNA; Regulation; Serine Protease; Suggestion; System; Testing; Time; Tissue Expansion; Transcript; Transcription Coactivator; Translations; Triad Acrylic Resin; Triglycerides; Tyrosine; Variant; alpha-glycerophosphoric acid; base; blood glucose regulation; epigenomics; gene environment interaction; glucose tolerance; imprint; improved; in vivo; insulin sensitivity; inter-individual variation; knock-down; novel; obesity development; obesity treatment; overexpression; promoter; small hairpin RNA

The rising global rate of obesity is caused by complex interactions between genetic, environmental and epigenetic factors. Gene-environment interactions are recognized as important for the development of obesity; however, the contribution of epigenetic-based mechanisms is not well defined. Using a diet-induced obesity susceptible genetically identical population of mice raised in controlled environmental conditions, we were able to identify potential epigenetic determinants of obesity. One of the genes that was identified, the paternally-expressed gene mesoderm specific transcript (Mest), was shown to have highly variable expression in white adipose tissue (WAT) and was positively associated with WAT expansion. Mouse strains developed by our laboratory with global and adipose tissue-specific inactivation of Mest showed that its inactivation is able to reduce high fat diet-mediated adipose tissue expansion and WAT inflammation, and improve glucose tolerance and insulin sensitivity. The stability of inter-individual variations of Mest expression in WAT is predictive for the development of obesity and suggestive of a `heritable' epigenetic mechanism for its regulation. Because Mest is coordinately regulated with the transcriptional activator Kruppel-like-factor 14 (Klf14) which resides ~200 kb downstream of the Mest locus on mouse Chr 6, it is possible that both genes are regulated by a common epigenetic pathway during metabolic imbalance. One of the goals of this proposal is to test whether Mest is regulated by an epigenetically heritable regulatory network that controls its expression in adipose tissue with dietary obesity (Aim 1). MEST belongs to the α/β hydrolase family of proteins which has a diversity of catalytic functions. Based on homology with similar proteins, MEST may function as an acyltransferase, lipase or epoxide hydrolase. We showed that MEST is localized within the endoplasmic reticulum (ER) membrane of adipocytes and co-localizes with lipid droplet surface proteins at ER-lipid droplet contact points. In vitro studies using mesenchymal progenitor cells derived from control or Mest-null mice, in concert with shRNA knockdown of Gpat4 suggest that MEST either possesses endogenous GPAT-like catalytic activity, or is an allosteric regulator of GPAT function. A second goal of this proposal will be to define how MEST functions to facilitate lipid accumulation in adipocytes (Aim 2). The aims of this proposal test our hypothesis that an epigenetic mechanism common to both Mest and Klf14 controls their expression in adipose tissue, and that inter-individual susceptibility for the development of obesity and impaired glucose homeostasis is caused by MEST-facilitated lipid accumulation in adipocytes via modulation of GPAT or EH activity at the ER-lipid droplet interface.

全球肥胖率上升是由遗传、环境和表观遗传因素之间的复杂相互作用引起的，基因-环境相互作用被认为对肥胖的发生很重要，但基于表观遗传的机制的作用尚不清楚。在受控环境条件下饲养的遗传相同的小鼠群体中，我们能够识别肥胖的潜在表观遗传决定因素，其中一个已识别的基因，即父本表达的基因中胚层特异性转录本（Mest），被证明具有肥胖易感性。白色表达高度可变我们实验室开发的具有全局和脂肪组织特异性灭活的 Mest 小鼠品系表明，其灭活能够减少高脂肪饮食介导的脂肪组织扩张和 WAT 炎症。改善葡萄糖耐量和胰岛素敏感性。WAT 中 Mest 表达的个体间变异的稳定性可预测肥胖的发生，并提示其调节的“可遗传”表观遗传机制。与位于小鼠 Chr 6 上 Mest 基因座下游约 200 kb 的转录激活因子 Kruppel 样因子 14 (Klf14) 协调调节，这两个基因可能在代谢失衡期间受到共同的表观遗传途径的调节。该提案的目标是测试 Mest 是否受到表观遗传调控网络的调控，该网络控制其在饮食性肥胖的脂肪组织中的表达（目标 1）。 α/β 水解酶家族蛋白具有多种催化功能，基于与相似蛋白的同源性，MEST 可能充当酰基转移酶、脂肪酶或环氧化物水解酶。使用源自对照或脂滴的间充质祖细胞进行体外研究，脂肪细胞与脂滴表面蛋白共定位于内质网脂滴接触点。 Mest 缺失小鼠与 Gpat4 的 shRNA 敲低相结合，表明 MEST 要么具有内源性 GPAT 样催化活性，要么是 GPAT 功能的变构调节剂。该提案的第二个目标是确定 MEST 如何发挥促进脂质积累的作用。该提案的目的是检验我们的假设，即 Mest 和 Klf14 共有的表观遗传机制控制着它们在脂肪组织中的表达，并且个体间存在这种机制。 MEST 通过调节 ER-脂滴界面上的 GPAT 或 EH 活性，促进脂肪细胞中的脂质积累，从而导致肥胖和葡萄糖稳态受损的易感性。