PDF(Pubmed)
Abstract：
Vascular smooth muscle cells (VSMCs), known for their remarkable lifelong phenotypic plasticity, play a pivotal role in vascular pathologies through their ability to transition between different phenotypes. Our group discovered that the deficiency of the mitochondrial protein Poldip2 induces VSMC differentiation both in vivo and in vitro. Further comprehensive biochemical investigations revealed Poldip2\'s specific interaction with the mitochondrial ATPase caseinolytic protease chaperone subunit X (CLPX), which is the regulatory subunit for the caseinolytic protease proteolytic subunit (ClpP) that forms part of the ClpXP complex - a proteasome-like protease evolutionarily conserved from bacteria to humans. This interaction limits the protease\'s activity, and reduced Poldip2 levels lead to ClpXP complex activation. This finding prompted the hypothesis that ClpXP complex activity within the mitochondria may regulate the VSMC phenotype. Employing gain-of-function and loss-of-function strategies, we demonstrated that ClpXP activity significantly influences the VSMC phenotype. Notably, both genetic and pharmacological activation of ClpXP inhibits VSMC plasticity and fosters a quiescent, differentiated, and anti-inflammatory VSMC phenotype. The pharmacological activation of ClpP using TIC10, currently in phase III clinical trials for cancer, successfully replicates this phenotype both in vitro and in vivo and markedly reduces aneurysm development in a mouse model of elastase-induced aortic aneurysms. Our mechanistic exploration indicates that ClpP activation regulates the VSMC phenotype by modifying the cellular NAD+/NADH ratio and activating Sirtuin 1. Our findings reveal the crucial role of mitochondrial proteostasis in the regulation of the VSMC phenotype and propose the ClpP protease as a novel, actionable target for manipulating the VSMC phenotype.
摘要：
血管平滑肌细胞（VSMC），以其非凡的终生表型可塑性而闻名，通过它们在不同表型之间转换的能力，在血管病变中发挥关键作用。我们小组发现线粒体蛋白Poldip2的缺乏在体内和体外诱导VSMC分化。进一步的全面生化研究揭示了Poldip2与线粒体ATPase酪蛋白分解蛋白酶分子伴侣X亚基（CLPX）的特异性相互作用，它是酪蛋白水解蛋白酶蛋白水解亚基（ClpP）的调节亚基，形成ClpXP复合物的一部分-从细菌到人类进化保守的蛋白酶体样蛋白酶。这种相互作用限制了蛋白酶的活性，和降低Poldip2水平导致ClpXP复杂激活。这一发现提示了线粒体内ClpXP复合物活性可能调节VSMC表型的假设。采用功能增益和功能丧失策略，我们证明ClpXP活性显著影响VSMC表型。值得注意的是,ClpXP的遗传和药理激活都会抑制VSMC的可塑性并促进静止，差异化,和抗炎VSMC表型。使用TIC10的ClpP的药理激活，目前在癌症的III期临床试验中，在弹性蛋白酶诱导的主动脉瘤小鼠模型中，成功地在体外和体内复制了这种表型，并显着减少了动脉瘤的发展。我们的机理探索表明，ClpP激活通过改变细胞NAD/NADH比率和激活Sirtuin1来调节VSMC表型。我们的研究结果揭示了线粒体蛋白稳定在VSMC表型调节中的关键作用，并提出了ClpP蛋白酶作为一种新的，用于操纵VSMC表型的可操作靶标。
