ROCK1 Signaling in Glucose Metabolism

描述（由申请人提供）：我们已经确定rho激酶（ROCK）是胰岛素作用和葡萄糖稳态的新型调节剂。具体来说，ROCK通过磷酸化丝氨酸残基直接调节IRS-1的功能。抑制ROCK功能导致胰岛素刺激的葡萄糖转运和胰岛素信号传导减少，导致胰岛素抵抗。我们发现ROCK1缺乏通过损害骨骼肌中的胰岛素信号传导导致体内全身性胰岛素抵抗。此外，在肥胖糖尿病小鼠和人类的骨骼肌中，胰岛素刺激的ROCK活性降低，表明ROCK活性缺陷可能与胰岛素抵抗的发病机制有关。因此，我们假设ROCK1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至关重要。本提案的总体目标是确定ROCK1在葡萄糖代谢和胰岛素信号传导调节中的新作用。Aim 1旨在确定IRS-1丝氨酸磷酸化在rock1依赖性葡萄糖代谢中的作用。我们将系统地研究ROCK1如何通过影响IRS-1丝氨酸磷酸化来控制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。Aim 2进一步阐明了ROCK1作为胰岛素对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胰岛素敏感细胞或ROCK1或IRS-1缺失的特定细胞系中ROCK1激活的基本基础。Aim 3定义了ROCK1在胰岛素靶组织的全身葡萄糖稳态和胰岛素敏感性中的作用。我们已经成功培育出loxP侧链的ROCK1小鼠，目前正在与表达MCK-Cre或脂联素- cre重组酶的小鼠杂交，产生肌肉或脂肪特异性ROCK1缺陷小鼠。这些小鼠将具有全身胰岛素敏感性和葡萄糖稳态的特征，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来确定一个新的分子机制，其中ROCK1是胰岛素控制代谢的重要关键节点，并可能为治疗糖尿病和肥胖提供一个新的靶点。

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.