Mechanism of SSH1L Phosphatase Activation in VSMC: Role in Vascular Pathology

血管平滑肌细胞（VSMC）迁移，其在体内主要是血小板衍生生长因子（PDGF）激活PDGF-β受体的结果，导致血管成形术后再狭窄和动脉粥样硬化。尽管细胞迁移涉及不同细胞类型和组织环境中的不同机制，但它是一个普遍的过程，在所有情况下都涉及肌动蛋白细胞骨架的重塑。Cofilin是通过刺激肌动蛋白丝的快速更新来调节肌动蛋白动力学的蛋白质。Cofilin通过弹弓磷酸酶SSH 1 L的去磷酸化而被激活。然而，导致SSHIL激活的机制尚不清楚。我们的初步数据强烈表明，NADPH氧化酶-1（Noxl）衍生的活性氧（ROS）参与SSH 1 L激活。根据这些意见，将调查三个具体目标。首先，将确定Nox 1衍生的ROS在SSH 1 L磷酸酶活化或亚细胞定位变化中的作用。其次，我们将表征负责ROS诱导的SSHIL激活VSMC的上游信号通路，特别是，我们将专注于参与蛋白质的合作伙伴，调节SSHIL活性。最后，SSH 1 L在新生内膜形成过程中VSMC迁移中的作用将被研究。这些研究将提供重要的洞察机制控制血管平滑肌细胞迁移，并可能有助于确定新的血管疾病的治疗靶点。总之，在本提案中，我们将探讨在分子水平上PDGF在VSMC中激活SSHIL的ROS依赖性机制的作用，并评估这种激活途径在体内的影响。这些研究将有助于确定潜在的治疗目标的病理，如动脉粥样硬化和再狭窄，涉及血管平滑肌细胞迁移失调。

Vascular smooth muscle cell (VSMC) migration, which in vivo is primarily the consequence of activation of the PDGF-p receptor by platelet-derived growth factor (PDGF), contributes to post-angioplasty restenosis and atherosclerosis. Although cell migration involves different mechanisms in different cell types and tissue environments, it is a universal process that in all cases involves remodelling of actin cytoskeleton. Cofilin is a protein that regulates actin dynamics by stimulating rapid turnover of actin filaments. Cofilin is activated by dephosphorylation by the Slingshot phosphatase SSH1L. However, the mechanisms leading to SSHIL activation are unknown. Our preliminary data strongly suggest that NADPH oxidase-1 (Noxl)-derived reactive oxygen species (ROS) participate in SSH1L activation. Based on these observations, three specific aims will be investigated. First, the role of Nox 1-derived ROS in SSH1L phosphatase activation or changes in subcellular localization will be determined. Second, we will characterize the upstream signaling pathways responsible for ROS-induced SSHIL activation in VSMC; particularly, we will focus on the participation of protein partners which regulate SSHIL activity. Finally, the role of SSH1L in VSMC migration during neointimal formation will be investigated. These studies will provide important insight into the mechanisms controlling vascular smooth muscle cell migration, and may help to identify new therapeutic targets for vascular disease. In summary, in this proposal we will explore the role of ROS-dependent mechanisms of SSHIL activation by PDGF at the molecular level in VSMC, and we will evaluate the impact of this activation pathway in vivo. These studies will help to identify potential therapeutic targets for pathologies such as atherosclerosis and restenosis that involve dysregulation of VSMC migration.