Transcriptional and epigenetic regulation of thermogenic adipocyte program

项目摘要/摘要 肥胖及其代谢后遗症在美国和世界范围内迅速增加，导致高 2型糖尿病、心血管疾病和某些癌症的发病率和死亡率。在海流下 在大流行期间，肥胖已被公认为严重新冠肺炎的关键风险因素。是这些病理的中心 是脂肪组织。在功能上有不同类型的脂肪组织。白色脂肪组织是主要的 甘油三酯仓库所在地。相比之下，由经典的棕色脂肪组成的生热脂肪 组织(BAT)和可诱导的米色/褐褐色脂肪细胞，集中在生热能量消耗上。它有 最近有报道称，患有BAT的人心脏代谢性疾病的患病率明显较低， 强调BAT对人体的新陈代谢益处和治疗潜力。为了让治疗学 如果可能，迫切需要对生热脂肪细胞的调控有更好的了解。这个 棕色和米色脂肪细胞的生热功能受特定转录和转录因子的协调调节 表观遗传调节器。而产热基因解偶联蛋白1(Ucp1)的转录则响应于 β-肾上腺素能刺激已经被广泛研究，但对组蛋白如何定位和 染色质折叠影响Ucp1和其他产热基因的表达。使用不带偏见的 基于CRISPR的筛选，我们鉴定了组蛋白变异体H_2A.Z和含有LIM结构域的锌指 蛋白Crip2作为反式作用因子被β3-肾上腺素能募集到Ucp1启动子/增强子区 感受器刺激。重要的是，成熟棕色脂肪细胞中H2A.Z或Crip2的缺失不仅阻碍了 UCP1转录，但也降低了多种致热基因的表达，导致细胞受损 生热作用。这项提议将确定介导Crip2和H2A.Z激活的信号事件 CRIP2或H_2A.Z缺乏在细胞产热和生物能谱中的沉积及其影响 生热脂肪细胞，小鼠和人类的起源。由于组蛋白变异体在 确定染色质重塑，我们将研究Crip2-H2A.Z相互作用如何影响染色质 结构，从而调节产热转录和细胞呼吸。要建立 Crip2和H2A.Z在代谢调节中的生理意义，我们将产生棕色脂肪特异性的Crip2 或H2A.Z基因敲除小鼠，并彻底鉴定它们的代谢表型。完成建议的 研究将增加对染色质重塑在调节 生热计划并为建立对抗代谢的新治疗方法铺平道路 疾病。

Project Summary/Abstract Obesity and its metabolic sequelae are rapidly increasing in the United States and worldwide, leading to high morbidity and mortality in type 2 diabetes, cardiovascular disease, and certain cancer. Under the current pandemic, obesity has been recognized as a key risk factor for severe COVID-19. Central to these pathologies is adipose tissue. There are functionally distinct types of adipose tissue. White adipose tissue is the primary site of the triglyceride storehouse. In contrast, thermogenic fat, which consists of classical brown adipose tissue (BAT) and inducible beige/brite adipocytes, concentrates on thermogenic energy expenditure. It has been recently reported that people with BAT have a significantly lower prevalence of cardiometabolic diseases, highlighting the metabolic benefits and therapeutic potential of BAT in humans. To make the therapeutics possible, improved knowledge of the regulation of thermogenic adipocytes is urgently needed. The thermogenic function of brown and beige adipocytes are coordinately regulated by specific transcriptional and epigenetic regulators. While transcription of the thermogenic gene uncoupling protein 1 (Ucp1) in response to beta-adrenergic stimulation has been broadly studied, little is known about how histone positioning and chromatin folding influences the expression of Ucp1 and other thermogenic genes. Using an unbiased CRISPR-based screen, we identified the histone variant H2A.Z and the LIM domaining-containing zinc-finger protein Crip2 as trans-acting factors recruited to the Ucp1 promoter/enhancer region by beta3-adrenergic receptor stimulation. Importantly, deletion of H2A.Z or Crip2 in mature brown adipocytes not only impeded Ucp1 transcription, but also reduced the expression of multiple thermogenic genes and led to impaired cellular thermogenesis. This proposal will determine the signaling events mediating the activation of Crip2 and H2A.Z deposition and the impact of Crip2 or H2A.Z deficiency in the cellular thermogenesis and bioenergetic profiles of thermogenic adipocytes murine and human origins. Since histone variants play an important role in determining chromatin remodeling, we will examine how Crip2-H2A.Z interaction influences chromatin architecture, thereby regulating thermogenic transcription and cellular respiration. To establish the physiological significance of Crip2 and H2A.Z in metabolic regulation, we will generate brown fat-specific Crip2 or H2A.Z knockout mice and thoroughly characterize their metabolic phenotypes. Completing the proposed studies will increase fundamental knowledge on the role of chromatin remodeling in the regulation of thermogenic program and pave ways to establish new therapeutic approaches for combating metabolic diseases.