Control of Vascular Smooth Muscle Function by Insulin

描述（由申请人提供）：糖尿病与心血管疾病风险增加相关，心血管疾病的部分原因是血管张力异常导致的血管平滑肌（VSM）收缩异常。该项目的总体目标是研究胰岛素如何调节细胞内信号转导通路，介导正常VSM的松弛，并确定糖尿病中潜在的通路缺陷。VSM的收缩和舒张主要由肌球蛋白轻链激酶和肌球蛋白结合磷酸酶（MBP）分别对调节性肌球蛋白轻链（MLC 20）进行磷酸化和去磷酸化介导。拟进行的研究将检验以下假设：1）胰岛素诱导的血管舒张是由MBP激活介导的，2）细胞对胰岛素和其他血管活性激素的敏感性和反应性是由调节磷酸酶MBP的肌球蛋白结合亚基（MBS）位点特异性磷酸化状态的因素控制的。使用主动脉组织，拟议的研究将检查1）MBP在胰岛素介导的VSM舒张中的作用，并确定MBS调节MBP酶活性的机制。2)明确PI 3-kinase/Akt和RhoA/Rho kinase在胰岛素介导的MBP激活中的作用，并确定糖尿病中这些通路的潜在缺陷; 3）研究血管紧张素II、内皮素I和白细胞介素-1 [3]/IL-6与胰岛素信号系统之间的潜在相互作用及其对Rho信号、MBS磷酸化和MBP酶活性的影响。利用腺病毒介导的基因转移技术，将目的基因（活化的MBS、PI 3-kinase、iNOS、Akt等）转染到主动脉组织中，研究其对肌球蛋白去磷酸化/舒张的关键调控成分的作用。累积起来，这项工作将导致确定MBS在MBP的胰岛素激活中的作用，以及胰岛素和胰岛素信号通路，细胞因子和其他血管活性激素之间的潜在串扰的MBP调节的分子基础。因此，在治疗背景下，MBP的活化在预防VSM的过度收缩性方面可能是有价值的，从而将对减少和/或预防糖尿病中的中风、心血管疾病和肾衰竭具有重要作用。

DESCRIPTION (provided by applicant): Diabetes is associated with increased risk of cardiovascular diseases, which arise in part due to abnormalities in vascular smooth muscle (VSM) contraction resulting from an abnormal vascular tone. The overall goal of this project is to examine how insulin regulates the intracellular signal transduction pathways, which mediate relaxation in normal VSM and to identify potential pathway defects in diabetes. Contraction and relaxation of VSM is mediated primarily by phosphorylation and dephosphorylation of the regulatory myosin light chain (MLC20) by myosin light chain kinase and myosin bound phosphatase (MBP) respectively. The proposed studies will test the hypotheses that 1) insulin-induced vasorelaxation is mediated by MBP activation, and 2) cellular sensitivity and responsiveness to insulin and other vasoactive hormones are controlled by the factors which regulate the site-specific phosphorylation status of the myosin-bound subunit (MBS) of the phosphatase, MBP. Using aortic tissue, the proposed studies will examine 1) the role of MBP in insulin-mediated relaxation of VSM and to identify the mechanism whereby MBS regulates the MBP enzymatic activity. 2) Define the roles of PI3-kinase/Akt and RhoA/Rho kinase in insulin-mediated MBP activation and identify potential defects in these pathways in diabetes, and 3) Investigate potential interactions between angiotensin II, endothelin I and interleukin-1 [3/IL-6 and insulin signaling system and its impact on Rho signaling, MBS phosphorylation and MBP enzymatic activity. The functions of the key regulatory components on myosin dephosphorylation/relaxation will be elucidated by transfecting the gene of interest (activated MBS, PI3-kinase, iNOS, Akt, etc) into aortic tissue using adenovirus mediated gene transfer technique. Cumulatively, this work will lead to define the role of MBS in insulin activation of MBP, and the molecular basis of MBP regulation by insulin and potential cross-talk between insulin signaling pathways, cytokines and other vasoactive hormones. Thus, in a therapeutic context, the activation of MBP could be of value in preventing excessive contractility of VSM and thereby will have an important effect on reducing and/or preventing stroke, cardiovascular disease and renal failure in diabetes.