Hepatic TNF Receptor Associated Factor (TRAF) 3 Promotes Insulin Resistance through the Ubiquitination of Insulin Receptor Substrate (IRS) 1 and 2

项目摘要 2型糖尿病是最常见的代谢性疾病，影响了近10%的美国人口。 鉴于它与肥胖症的密切联系，不仅流行率预计在未来会增加，而且 患有这种疾病的人患严重健康并发症的风险更高，包括 心血管疾病，这仍然是糖尿病患者的主要死亡原因。因此，它是 当务之急是制定更好的治疗策略，以管理疾病的进展及其 相关的健康风险。许多因素，包括遗传因素和环境因素，都有助于2型的表现。 糖尿病；然而，外周胰岛素抵抗的发展仍然是最强的病因预测因素。 疾病的进展。大量科学证据表明，慢性炎症，特别是在 肥胖的背景，促进了细胞胰岛素抵抗。具体地说，促炎细胞因子是 在代谢性疾病中升高，并能抑制组织部位的胰岛素依赖的信号通路，如 肝脏。最近，一种被称为肿瘤坏死因子受体相关因子的蛋白质家族之间的独特联系 (TRAF)和胰岛素抵抗的发展。TRAF蛋白是一种重要的调节因子 细胞因子信号转导，但它们在肝脏中的作用，特别是肝细胞，还没有很好的定义。初步数据 提示TRAF3负性调节原代肝细胞的胰岛素敏感性 通过促进胰岛素受体底物1和2的泛素化，在转基因小鼠中也是如此 (IRS1/2)，它们是促进胰岛素信号转导通路的重要适配蛋白。 目标单元格。因此，这一建议的工作假设是肝脏TRAF3直接表达 通过改变IRS1/2适配器蛋白的泛素化，促进肝脏中的胰岛素抵抗。为了测试这一点 假设，提出了两个目标。目标1试图确定驱动肝脏的机制 TRAF3在肥胖中的诱导。初步数据显示，TRAF3在肥胖小鼠模型中表达上调。 为了确定发生这种情况的机制，在初级教育中进行的各种方法 肝细胞和小鼠模型，将被用来研究细胞因子、游离脂肪酸和 脂多糖以Toll样受体依赖的方式促进TRAF3的上调。目标2 旨在确定TRAF3促进胰岛素抵抗的分子机制。具体来说， TRAF3的S作为泛素连接酶的作用将是利用转基因小鼠品系，分子生物学和 分析化学技术，如质谱学，以确定IRS1/2泛素化和 它在肝脏中的功能结果。总而言之，这些研究将推动科学理解如何 炎症和胰岛素抵抗是联系在一起的，也为治疗2型糖尿病提供了新的方法和策略 及其相关的并发症。

Project Abstract Type 2 diabetes is the most common metabolic disease and affects nearly 10% of the American population. Given its close association with obesity, not only is the prevalence expected to increase in the future, but individuals with the disease are at a higher risk for developing severe health complications, including cardiovascular disease, which remains the leading cause of death for diabetic patients. Therefore, it is imperative that better treatment strategies are developed to manage the progression of the disease and its associated health risks. Many factors, both genetic and environmental, contribute to the manifestation of type 2 diabetes; however, the development of peripheral insulin resistance remains the strongest etiological predictor of disease progression. An abundance of scientific evidence suggests that chronic inflammation, particularly in the setting of obesity, promotes cellular insulin resistance. Specifically, pro-inflammatory cytokines are elevated in metabolic diseases and can inhibit insulin-dependent signaling pathways in tissue sites such as the liver. Recently, a unique link between a family of proteins known as the TNF receptor-associated factors (TRAFs) and the development of insulin resistance has been developed. TRAF proteins are key mediators in cytokine signaling, but their role in the liver, particularly hepatocytes, are not well defined. Preliminary data suggests that one specific member, TRAF3, negatively regulates insulin sensitivity in primary hepatocytes as well as in transgenic mouse models by promoting the ubiquitination of insulin receptor substrates 1 and 2 (IRS1/2), which function as important adaptor proteins that facilitate insulin signaling transduction pathways in target cells. Therefore, the working hypothesis of this proposal is that hepatic TRAF3 expression directly promotes insulin resistance in the liver through altered ubiquitination of IRS1/2 adaptor proteins. To test this hypothesis, two aims have been developed. Aim 1 seeks to determine the mechanisms that drive hepatic TRAF3 induction in obesity. Preliminary data suggests that TRAF3 is up-regulated in mouse models of obesity. To determine the mechanisms by which this occurs, a variety of approaches, conducted in primary hepatocytes and mouse models, will be employed to investigate the roles of cytokines, free fatty acids, and lipopolysaccharide in promoting TRAF3 up-regulation in a Toll-like and TNF receptor-dependent fashion. Aim 2 seeks to determine the molecular mechanisms by which TRAF3 promotes insulin resistance. Specifically, TRAF3's role as a ubiquitin ligase will be the focus by using transgenic mouse strains, molecular biology and analytical chemistry techniques, such as mass spectrometry, to identify the sites of IRS1/2 ubiquitination and its functional outcome in the liver. Together, these studies will advance the scientific understanding of how inflammation and IR are linked, as well as provide novel approaches and strategies to treat type 2 diabetes and its associated complications.