Li P F, Maasch C, Haller H, Dietz R, von Harsdorf R
Department of Cardiology, Franz Volhard Clinic, Humboldt University Berlin, Germany.
Circulation. 1999 Aug 31;100(9):967-73. doi: 10.1161/01.cir.100.9.967.
Vascular smooth muscle cell (VSMC) apoptosis is a component of a variety of cardiovascular diseases and may be related to reactive oxygen species (ROS). This study was designed to determine the role of protein kinase C (PKC) in ROS-induced VSMC apoptosis.
Rat aortic VSMCs were exposed to H(2)O(2), and the nature of cell death was characterized in the absence or presence of different PKC inhibitors. The results demonstrate that exposure of VSMCs to H(2)O(2) led to a dose-dependent (25 to 100 micromol/L) and time-dependent (peak at 2 minutes) activation of PKC. Among the PKC isoforms alpha, beta, delta, epsilon, and zeta, only PKC-alpha and PKC-epsilon were found to change their intracellular distribution on H(2)O(2) treatment. Apoptosis was the predominant form of cell death when PKC had been activated by H(2)O(2) alone or by H(2)O(2) in the presence of 50 nmol/L phorbol 12-myristate 13-acetate. In contrast, necrosis became the predominant form of cell death when PKC had been downregulated by prolonged exposure to 200 nmol/L phorbol 12,13-dibutyrate or inhibited by 50 nmol/L staurosporine, 100 nmol/L calphostin C, or 30 micromol/L H-7. In addition, caspase-3 was activated in H(2)O(2)-induced VSMC apoptosis but not when PKC was downregulated or inhibited. Inhibition of caspase-3 by 50 micromol/L Ac-DEVD-CHO could significantly attenuate H(2)O(2)-induced apoptosis and was not associated with the induction of necrosis.
We conclude that in VSMCs, PKC converts the ROS-induced signals from necrotic cell death to the activation of an apoptotic cell death program. These data imply a novel and important role of PKC for the pathogenesis of such vascular diseases as atherosclerosis, restenosis, and hypertension.
血管平滑肌细胞（VSMC）凋亡是多种心血管疾病的组成部分，可能与活性氧（ROS）有关。本研究旨在确定蛋白激酶C（PKC）在ROS诱导的VSMC凋亡中的作用。
将大鼠主动脉VSMC暴露于H₂O₂，并在存在或不存在不同PKC抑制剂的情况下对细胞死亡的性质进行表征。结果表明，VSMC暴露于H₂O₂会导致PKC的剂量依赖性（25至100 μmol/L）和时间依赖性（2分钟时达到峰值）激活。在PKC亚型α、β、δ、ε和ζ中，仅发现PKC-α和PKC-ε在H₂O₂处理后其细胞内分布发生变化。当PKC单独被H₂O₂激活或在存在50 nmol/L佛波醇12-肉豆蔻酸酯13-乙酸酯的情况下被H₂O₂激活时，凋亡是细胞死亡的主要形式。相反，当通过长时间暴露于200 nmol/L佛波醇12,13-二丁酸酯使PKC下调或被50 nmol/L星形孢菌素、100 nmol/L钙磷蛋白C或30 μmol/L H-7抑制时，坏死成为细胞死亡的主要形式。此外，caspase-3在H₂O₂诱导的VSMC凋亡中被激活，但在PKC下调或抑制时未被激活。50 μmol/L Ac-DEVD-CHO对caspase-3的抑制可显著减轻H₂O₂诱导的凋亡，且与坏死的诱导无关。
我们得出结论，在VSMC中，PKC将ROS诱导的信号从坏死性细胞死亡转换为凋亡性细胞死亡程序的激活。这些数据暗示PKC在动脉粥样硬化、再狭窄和高血压等血管疾病的发病机制中具有新的重要作用。
