Targeting Insulin Resistance by Estrogen Receptor in Control of Type 2 Diabetes Mellitus

项目摘要 “雌激素受体靶向胰岛素抵抗在2型糖尿病控制中的作用” 阐述了基于性别差异的2型糖尿病控制的基本机制。性别 T2D的发病率存在差异，女性对胰岛素的敏感性和存活率有所改善，但 机制尚不清楚。性激素雌激素及其受体系统对新陈代谢有好处 功能。该提案将阐述雌激素和胰岛素的分子和生理机制 IRS1和IRS2蛋白及下游蛋白激酶Akt和Forkhead水平的信号串扰 转录因子Foxo1通过血红素加氧酶1控制线粒体的生物发生和功能 (HO1)基因。 叉头转录因子Foxo1的O-类是Foxo1的关键下游靶点 胰岛素→PI3K蛋白激酶B(→Protein Kinase B，AKT)信号通路，调节多种生理功能。我们的 先前的研究表明，Foxo1是Akt的关键底物，位于胰岛素和 雌激素信号通过葡萄糖-6-磷酸酶基因的表达控制葡萄糖的动态平衡。Foxo1也 刺激血红素加氧酶-1(HO1)的表达，以催化血红素的降解，血红素是 线粒体电子传递链，进而降低线粒体的生物发生和功能。 在这个方案中，我们假设胰岛素和17-β-雌二醇(E_2)在激活 PI3K-Akt和抑制Foxo1-HO1对线粒体功能的控制，而IRS1/2和雌激素的丢失 受体-α(ER-α)信号和由此产生的HO1过表达是基本和统一的机制 用于促进化炎症的线粒体功能障碍。在目标1中，我们使用肝脏特异性ER-α 在胰岛素抵抗小鼠中进行基因敲除，并检测IR 1、2和IR 1、2和ERα基因是否需要 相关的PI3K-AKT激活和抑制肝脏中的Foxo1和HO1。在AIM2中，我们将使用蛋白质- 蛋白质相互作用分析确定ERα与irs1和irs2相互作用的关键域，激活 PI3K-Akt和抑制细胞内Foxo1-HO1。我们检验了这样一种假设，即N端ERα没有DNA 结合结构域(DBD)与IRS1/2相互作用，阻止IRS1/2丝氨酸磷酸化偶联降解， 抑制细胞内Foxo1和HO1的表达。在目标3中，我们将使用腺病毒介导的N-末端基因表达 用高脂饲料喂养的小鼠体内的结构域ERα检测是否存在通过激活IRS-来实现肝脏保护 相关的PI3K和抑制Foxo1和HO1。此外，我们将以纳米颗粒介导的HO1为靶点 高脂饮食或IRS1/2和ERα缺失小鼠肝脏中HO1抑制物(锌原卟啉)的表达 胰岛素抵抗。我们将研究抑制HO1是否足以保护肝脏线粒体 胰岛素抵抗小鼠的功能障碍和炎症。因此，这一提议将提供新的机制。 ER、α和HO1在胰岛素增敏中的作用及胰岛素增敏剂的治疗进展 2型糖尿病的治疗。

Project Summary This proposal “Targeting Insulin Resistance by Estrogen Receptor in Control of Type 2 Diabetes Mellitus” addresses a fundamental mechanism based on the gender difference in control of type 2 diabetes. The gender difference exists for the incidence of T2D, with improved insulin sensitivity and survival in females, but the mechanism is unclear. Sex hormone estrogen and its receptor system have shown benefit to metabolic function. This proposal will address the molecular and physiological mechanism by which estrogen and insulin signaling crosstalk at the level of IRS1 and IRS2 proteins and downstream protein kinase Akt and forkhead transcription factor Foxo1 that controls mitochondrial biogenesis and function through the heme oxygenase 1 (HO1) gene. The O-class of the forkhead transcription factor Foxo1 is a key downstream target of the insulin→PI3K→protein kinase B (Akt) signaling pathway, governing multiple physiological functions. Our previous studies have demonstrated Foxo1 is a key substrate of Akt downstream from both insulin and estrogen signaling that controls glucose homeostasis via glucose-6-phosphatase gene expression. Foxo1 also stimulates expression of heme-oxygenase-1 (HO1) that catalyzes degradation of heme, a key component of mitochondrial electron transport chains, then reducing mitochondrial biogenesis and function. In this proposal, we hypothesize that insulin and 17-beta-estradiol (E2) play important roles in activation of PI3K-Akt and suppressing Foxo1-HO1 in control of mitochondrial function, while loss of IRS1/2 and estrogen receptor-alpha (ERα) signaling and resultant HO1 overexpression are fundamental and unifying mechanisms for mitochondrial dysfunction that promotes meta-inflammation. In Aim 1, we use the liver-specific ER-alpha gene knockout mice in insulin resistant mice and examine whether ERα gene is required for IRS1, 2 and associated PI3K-AKT activation and suppression of Foxo1 and HO1 in the liver. In Aim2, we will use protein- protein interaction assays to map out the key domain of ERα for interaction with IRS1 and IRS2, activating PI3K-Akt and inhibiting Foxo1-HO1 in cells. We test the hypothesis that either N-terminal ERα without DNA binding domain (DBD) interacts with IRS1/2, preventing IRS1/2 serine phosphorylation coupled degradation, suppressing Foxo1 and HO1 in cells. In Aim 3, we will use adenovirus-mediated gene expression of N-terminal domain ERα in HFD-fed mice to examine whether there is achievable hepatic protection by activation of IRS- associated PI3K and suppression of Foxo1 and HO1. Moreover, we will target HO1 with nanoparticle-mediated HO1 inhibitor (Zn2+-protoporphyrin) in the liver of mice lacking IRS1/2 and ERα or high fat-diet (HFD)-induced insulin resistance. We will examine whether HO1 inhibition sufficiently protects hepatic mitochondrial dysfunction and inflammation in insulin resistant mice. Therefore, this proposal will provide novel mechanisms of ERα and HO1 in insulin sensitizing and approaches of therapeutic development for insulin sensitizers in the treatment of type 2 diabetes.