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

项目摘要 该提案“通过雌激素受体靶向胰岛素抵抗控制2型糖尿病” 2型糖尿病的治疗方法有哪些？性别 T2 D的发病率存在差异，女性的胰岛素敏感性和生存率有所改善，但 机制尚不清楚。性激素雌激素及其受体系统已显示出有益于代谢 功能这项建议将解决雌激素和胰岛素的分子和生理机制， IRS 1和IRS 2蛋白以及下游蛋白激酶Akt和forkhead水平的信号串扰 通过血红素加氧酶1控制线粒体生物发生和功能的转录因子Foxo 1 (HO1)基因 叉头转录因子Foxo 1的O类是转录因子Foxo 1的关键下游靶点。 胰岛素→ PI 3 K →蛋白激酶B（Akt）信号通路，调控多种生理功能。我们 先前的研究已经证明Foxo 1是Akt的关键底物，其位于胰岛素和 通过葡萄糖-6-磷酸酶基因表达控制葡萄糖稳态的雌激素信号传导。Foxo1 刺激血红素加氧酶-1（HO 1）的表达，HO 1催化血红素的降解，血红素是 线粒体电子传递链，然后减少线粒体的生物发生和功能。 在这个建议中，我们假设胰岛素和17-β-雌二醇（E2）在激活 PI 3 K-Akt和抑制Foxo 1-HO 1控制线粒体功能，而IRS 1/2和雌激素的损失 受体α（ERα）信号传导和由此产生的HO 1过表达是基本和统一的机制 线粒体功能障碍会促进炎症在目标1中，我们使用肝脏特异性ER-α 基因敲除小鼠中的胰岛素抵抗小鼠，并检查ERα基因是否是IRS 1，2和 相关的PI 3 K-AKT激活和肝脏中Foxo 1和HO 1的抑制。在目标2中，我们将使用蛋白质- 蛋白质相互作用测定，以绘制ERα与IRS 1和IRS 2相互作用的关键结构域，激活 PI 3 K-Akt和抑制细胞中的Foxo 1-HO 1。我们检验了一个假设，即N-末端ERα不含DNA， 结合结构域（DBD）与IRS 1/2相互作用，阻止IRS 1/2丝氨酸磷酸化偶联降解， 抑制细胞中的Foxo 1和HO 1。在目的3中，我们将使用腺病毒介导的N-末端基因表达， 结构域ERα，以检查是否存在通过激活IRS- 相关的PI 3 K以及Foxo 1和HO 1的抑制。此外，我们将靶向HO 1与纳米粒子介导的 HO 1抑制剂（Zn 2 +-原卟啉）在缺乏IRS 1/2和ERα或高脂饮食（HFD）诱导的小鼠肝脏中的表达 胰岛素抵抗我们将研究HO 1抑制是否足以保护肝线粒体 胰岛素抵抗小鼠的功能障碍和炎症。因此，该提议将提供新颖的机制 ERα和HO 1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.