MLC Dephosphorylation in Smooth Muscle Cell Apoptosis

细胞骨架在程序性细胞死亡（凋亡）过程中发生剧烈变化，肌动蛋白参与介导这些细胞骨架的变化。虽然肌动蛋白和肌球蛋白II协同工作，但对肌球蛋白II的作用及其通过肌球蛋白轻链磷酸化在平滑肌细胞凋亡机制中的调节知之甚少。我们已经做了三个观察，影响细胞凋亡过程中的细胞骨架动力学的调节。首先，肌球蛋白轻链在细胞凋亡过程中被去磷酸化;其次，肌球蛋白轻链激酶（MLCK）的活性，磷酸化肌球蛋白II的酶，在细胞凋亡过程中降低;第一，肌球蛋白轻链在细胞凋亡过程中被去磷酸化。第二，肌球蛋白轻链激酶（MLCK）（磷酸化肌球蛋白II的酶）的活性在细胞凋亡期间降低;第二，肌球蛋白轻链激酶（MLCK）（磷酸化肌球蛋白II的酶）的活性在细胞凋亡期间降低;第三，使用药理学试剂长期抑制MLCK活性导致核碎裂和基因组消化。基于这些数据，我提出的假设，肌球蛋白轻链去磷酸化是必要的，并可能启动细胞骨架的变化特征的程序性细胞死亡。具体来说，我将解决MLCK去磷酸化在血管平滑肌细胞死亡中的作用，并确定如何在分子水平上进行调节。这项建议的具体目标是：1.建立肌球蛋白轻链去磷酸化与平滑肌细胞凋亡的关系。2.确定“非凋亡MLCK去磷酸化”在暴露于促炎细胞因子TNF-α、IL-1 β和IFN-γ后使平滑肌细胞敏感而发生凋亡中的功能。从这些研究中获得的信息将增加我们对细胞凋亡过程中细胞骨架动力学的理解。

The cytoskeleton undergoes dramatic changes during programmed cell death (apoptosis) and actin has been implicated in mediating these cytoskeletal changes. Although actin and myosin II work in concert, little is known about the role of myosin II and its regulation by myosin light chain phosphorylation in the mechanism of smooth muscle cell apoptosis. We have made three observations that impact the regulation of cytoskeletal dynamics during apoptosis. First, myosin light chains are dephosphorylated during apoptosis; Second, the activity of myosin light chain kinase (MLCK), the enzyme that phosphorylates myosin II, is decreased during apoptosis; First, myosin light chains are dephosphorylated during apoptosis. Second, the activity of myosin light chain kinase (MLCK), the enzyme that phosphorylates myosin II, is decreased during apoptosis; Second, the activity of myosin light chain kinase (MLCK), the enzyme that phosphorylates myosin II, is decreased during apoptosis; Third, prolonged inhibition of MLCK activity using a pharmacological agent results in nuclear fragmentation and genome digestion. Based on these data, I propose the hypothesis that myosin light chain dephosphorylation is necessary for and perhaps initiates the cytoskeletal changes characteristic of programmed cell death. Specifically, I will address the role of MLCK dephosphorylation in vascular smooth muscle cell death and determine how this may be regulated at the molecular level. The specific aims of this proposal are to: 1. Establish the relation between myosin light chain dephosphorylation and apoptosis of smooth muscle cells. 2. Determine the function of "non-apoptotic MLCK dephosphorylation" in sensitizing the smooth muscle cells to undergo apoptosis following exposure to the pro-inflammatory cytokines TNF-alpha, IL-1beta and IFN-gamma. The information derived from these studies will increase our understanding of cytoskeletal dynamics during apoptosis.