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变化。尽管肌动蛋白和肌凝蛋白II协同工作，但对肌凝蛋白II的作用及其通过肌凝蛋白轻链磷酸化调控在平滑肌细胞凋亡机制中的作用知之甚少。我们做了三个观察，影响细胞凋亡过程中细胞骨架动力学的调节。首先，在细胞凋亡过程中肌球蛋白轻链被去磷酸化；其次，肌球蛋白轻链激酶（MLCK）的活性在细胞凋亡过程中降低，MLCK是磷酸化肌球蛋白II的酶；首先，在细胞凋亡过程中肌球蛋白轻链被去磷酸化。其次，肌球蛋白轻链激酶（MLCK）的活性在细胞凋亡过程中降低，MLCK是磷酸化肌球蛋白II的酶；其次，肌球蛋白轻链激酶（MLCK）的活性在细胞凋亡过程中降低，MLCK是磷酸化肌球蛋白II的酶；第三，使用药物长期抑制MLCK活性会导致核断裂和基因组消化。基于这些数据，我提出一个假设，即肌球蛋白轻链去磷酸化是必要的，并且可能启动程序性细胞死亡特征的细胞骨架变化。具体来说，我将讨论MLCK去磷酸化在血管平滑肌细胞死亡中的作用，并确定这在分子水平上是如何调节的。本建议的具体目的是：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“非凋亡性MLCK去磷酸化”在暴露于促炎细胞因子tnf - α、il -1 β和ifn - γ后使平滑肌细胞敏化发生凋亡中的作用。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.