Dnmt3a as an epigenetic mediator of insulin resistance

Dnmt3a 作为胰岛素抵抗的表观遗传介质

• 批准号: 10063521
• 负责人: Sona Kang
• 金额: $ 37.76万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-12-01 至 2022-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10063521
• 关键词: Adipocytes; Adipose tissue; Aging; Agonist; Animals; Area; Biological; Biological Markers; Body Composition; Body Weight; Cardiovascular Diseases; Cells; Chemicals; Clinical; Complication; Cytosine; DNA Methylation; DNA Modification Methylases; DNA Modification Process; DNA methylation profiling; DNMT3a; Data; Development; Disease; Environment; Epigenetic Process; Etiology; Event; Family; Functional disorder; Gene Expression; Gene Expression Profiling; Gene Expression Regulation; Gene Targeting; Genes; Genetic Epistasis; Genetic Transcription; Genetic study; Goals; Health; High Fat Diet; Human; In Vitro; Insulin Resistance; Knock-in; Knockout Mice; Lead; Mediating; Metabolic; Metabolism; Mitochondria; Modification; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nucleic Acid Regulatory Sequences; Obesity; Organism; PPAR gamma; Pathogenesis; Pathogenicity; Pathway interactions; Pattern; Pharmacology Study; Positioning Attribute; Regulation; Repression; Research; Role; Signal Transduction; Site; Testing; Uncertainty; adipocyte differentiation; base; differential expression; endoplasmic reticulum stress; gene environment interaction; glucose tolerance; human disease; human model; improved; in vivo; insulin mediators; insulin sensitivity; insulin sensitizing drugs; insulin signaling; mouse model; novel marker; promoter; response; rosiglitazone; therapeutic target

Insulin resistance (IR) is the pathophysiological hallmark of type 2 diabetes and obesity. Although several biological pathways have been proposed to be behind IR, there is still a great deal of uncertainty about the mechanisms by which cells and organisms become insulin resistant. The etiology of IR involves intricate interactions between genes and the environment, interactions mediated by epigenetic mechanisms. DNA methylation is a major epigenetic modification that is performed by DNA methyltransferases (Dnmts). Altered patterns of DNA methylation associate with a variety of metabolic perturbations, yet the cause-and-effect relationship remains poorly understood. Our recent studies have demonstrated that IR associates with many locus-specific changes in epigenetic modification. While we were searching for differentially expressed epigenetic modifiers, we discovered that adipose expression of Dnmts was elevated in mouse models of IR and that the increased expression was largely reversed by the insulin sensitizer Rosiglitazone. We have shown that Dnmt3a, in particular among the Dmnt family, is both necessary and sufficient to mediate IR in cultured adipocytes. Consistent with our in vitro results, our primary in vivo studies found that adipose-specific Dnmt3a-knockout mice had improved whole-body insulin sensitivity and glucose tolerance. Furthermore, our gene profiling studies identified Fgf21 as a key target gene repressed by Dnmt3a, with concordant changes in DNA methylation at its promoter. Based on these findings, we hypothesize that adipose Dnmt3a mediates IR by regulating key metabolic genes through altering site-specific DNA methylation at critical cis-regulatory regions. To test our central hypothesis, we will pursue the following aims. Aim 1 is to ascertain the role of Dnmt3a in cell-autonomous IR and to delineate the epistatic relationship of Dnmt3a and PPARγ. Aim 2 is to investigate the full impact of adipose-specific Dnmt3a depletion on whole-body metabolism and to elucidate the underlying mechanisms of the improved insulin sensitivity, and Aim 3 is to elucidate the underlying molecular and epigenetic basis through which Dnmt3a mediates IR using both focused and unbiased approaches. Overall, this research will establish the role of adipose Dnmt3a in the pathophysiology of IR and elucidate the underlying molecular and epigenetic mechanisms. It may also provide novel biomarkers of IR and reveal therapeutic target(s) for IR.

胰岛素抵抗（IR）是 2 型糖尿病和肥胖的病理生理标志。尽管IR背后存在多种生物学途径，但细胞和生物体产生胰岛素抵抗的机制仍然存在很大的不确定性。 IR 的病因涉及基因与环境之间复杂的相互作用，这些相互作用是由表观遗传机制介导的。 DNA 甲基化是一种主要的表观遗传修饰，由 DNA 甲基转移酶 (Dnmts) 执行。 DNA 甲基化模式的改变与各种代谢扰动相关，但其因果关系仍知之甚少。 我们最近的研究表明，IR 与表观遗传修饰中的许多位点特异性变化相关。当我们寻找差异表达的表观遗传修饰剂时，我们发现 IR 小鼠模型中 Dnmts 的脂肪表达升高，并且胰岛素增敏剂罗格列酮在很大程度上逆转了这种升高的表达。我们已经证明，Dnmt3a，特别是 Dmnt 家族中的 Dnmt3a，对于介导培养脂肪细胞中的 IR 是必要且充分的。与我们的体外结果一致，我们的初步体内研究发现，脂肪特异性 Dnmt3a 敲除小鼠的全身胰岛素敏感性和葡萄糖耐量得到改善。此外，我们的基因分析研究发现 Fgf21 是 Dnmt3a 抑制的关键靶基因，其启动子处的 DNA 甲基化发生了一致的变化。基于这些发现，我们假设脂肪 Dnmt3a 通过改变关键顺式调控区域的位点特异性 DNA 甲基化来调节关键代谢基因，从而介导 IR。 为了检验我们的中心假设，我们将追求以下目标。目标 1 是确定 Dnmt3a 在细胞自主 IR 中的作用并描绘 Dnmt3a 和 PPARγ 的上位关系。目标 2 是研究脂肪特异性 Dnmt3a 耗竭对全身代谢的全面影响，并阐明改善胰岛素敏感性的潜在机制，目标 3 是使用有针对性和无偏见的方法阐明 Dnmt3a 介导 IR 的潜在分子和表观遗传基础。总的来说，这项研究将确定脂肪 Dnmt3a 在 IR 病理生理学中的作用，并阐明潜在的分子和表观遗传机制。它还可以提供新的 IR 生物标志物并揭示 IR 的治疗靶点。