ROCK1 Signaling in Glucose Metabolism

描述（由申请人提供）：我们已经确定Rho激酶（ROCK）是一种新型的胰岛素作用和葡萄糖稳态调节剂。具体而言，ROCK通过磷酸化丝氨酸残基直接调节IRS-1功能。ROCK功能的抑制导致胰岛素刺激的葡萄糖转运和胰岛素信号传导的减少，从而导致胰岛素抵抗。我们发现ROCK 1缺陷通过损害骨骼肌中的胰岛素信号传导而在体内引起全身性胰岛素抵抗。此外，胰岛素刺激的ROCK活性在肥胖糖尿病小鼠和人的骨骼肌中降低，表明ROCK活性缺陷可能有助于胰岛素抵抗的发病机制。因此，我们假设ROCK 1的激活对于胰岛素通过IRS-1丝氨酸磷酸化对葡萄糖转运和胰岛素信号传导的代谢作用是至关重要的。该提案的总体目标是确定ROCK 1在葡萄糖代谢和胰岛素信号转导调节中的新作用。目的1研究IRS-1丝氨酸磷酸化在ROCK 1依赖性糖代谢中的作用。我们将系统研究ROCK 1如何通过影响IRS-1丝氨酸磷酸化来调控胰岛素介导的葡萄糖代谢。这将通过在IRS-1缺陷细胞和小鼠中重新引入IRS-1突变体来实现。目的2进一步阐明ROCK 1是胰岛素作用于葡萄糖转运和下游信号传导的关键调节因子的分子机制。我们将使用小RNA干扰和腺病毒基因转移策略来确定胰岛素诱导的ROCK 1在胰岛素敏感细胞或ROCK 1或IRS-1缺失的特定细胞系中激活的基本基础。目的3定义ROCK 1在全身葡萄糖稳态和胰岛素靶组织中的胰岛素敏感性中的作用。我们已经成功地产生loxP侧翼ROCK 1小鼠，目前正在与表达MCK-Cre或脂联素-Cre重组酶的小鼠繁殖，产生肌肉或脂肪特异性ROCK 1缺陷小鼠。这些小鼠将被表征为全身胰岛素敏感性和葡萄糖稳态，这对预防糖尿病的策略具有重要意义。这些研究提供了一个独特的机会，以确定一种新的分子机制，其中ROCK 1是重要的胰岛素控制代谢的关键节点，并可能提供一个新的目标，用于治疗糖尿病和肥胖症。 胰岛素抵抗是2型糖尿病的主要危险因素，其原因尚不完全清楚。初步数据显示，ROCK 1功能的抑制导致胰岛素反应降低，导致胰岛素抵抗。该研究的目的是确定ROCK 1在胰岛素控制葡萄糖代谢中的生物学功能，这些实验可能会导致新糖尿病药物的潜在靶点的确定。

DESCRIPTION (provided by applicant): We have identified Rho-Kinase (ROCK) as a novel regulator of insulin action and glucose homeostasis. Specifically, ROCK directly regulates IRS-1 function by phosphorylating serine residues. Inhibition of ROCK function results in a reduction of insulin-stimulated glucose transport and insulin signaling, leading to insulin resistance. We found that ROCK1 deficiency causes systemic insulin resistance in vivo by impairing insulin signaling in skeletal muscle. Furthermore, insulin-stimulated ROCK activity is decreased in the skeletal muscle of obese diabetic mice and humans, suggesting that defective ROCK activity may contribute to the pathogenesis of insulin resistance. We thus hypothesize that activation of ROCK1 is critical for the metabolic action of insulin on glucose transport and insulin signaling through IRS-1 serine phosphorylation. The overall objective of this proposal is to define the novel role of ROCK1 in the regulation of glucose metabolism and insulin signaling. Aim 1 works to determine the role of IRS-1 serine phosphorylation in ROCK1-dependent glucose metabolism. We will systemically investigate how ROCK1 controls insulin- mediated glucose metabolism via affecting IRS-1 serine phosphorylation. This will be achieved by reintroducing IRS-1 mutants in IRS-1-deficient cells and mice. Aim 2 further elucidates the molecular mechanism in which ROCK1 is a key regulator of insulin action on glucose transport and downstream signaling. We will use small RNA interference and adenovirus gene-transfer strategies to determine the fundamental basis underlying insulin-induced activation of ROCK1 in insulin-sensitive cells or specific cell lines in which ROCK1 or IRS-1 has been deleted. Aim 3 defines the role of ROCK1 in whole-body glucose homeostasis and insulin sensitivity in insulin-target tissues. We have successfully generated loxP flanked ROCK1 mice, which are currently being breed with mice expressing MCK-Cre or adiponectin-Cre recombinase producing muscle- or adipose-specific ROCK1-deficient mice. These mice will be characterized for whole-body insulin sensitivity and glucose homeostasis, with important implications for strategies to prevent diabetes. These studies provide a unique opportunity to identify a novel molecular mechanism in which ROCK1 is important as a critical node in insulin control of metabolism, and may offer a novel target for the treatment of diabetes and obesity. PUBLIC HEALTH RELEVANCE: Insulin resistance is a major risk factor for type 2 diabetes, and the cause of this is not fully understood. Preliminary data show that the inhibition of the ROCK1 function results in a decreased insulin response, leading to insulin resistance. The goal of the study is to determine the biological function of ROCK1 in insulin control of glucose metabolism, and these experiments could lead to the identification of a potential target for new diabetes drugs.