Department of Pharmacology, Cardiac and Cerebrovascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, 74 Zhongshan 2 Rd, 510080, Guangzhou, People's Republic of China.
Apoptosis. 2013 Oct;18(10):1262-73. doi: 10.1007/s10495-013-0881-z.
Endothelial progenitor cells (EPCs) play an important role in postnatal neovascularization and re-endothelialization in response to tissue ischemia and endothelial injury. It is reported that the circulating EPCs number is decreased during hypertension. However, the detailed mechanism is still unclear. Our previous studies have shown that ClC-3 chloride channel is up-regulated with the development of hypertension. This study aims to test whether ClC-3 participates in EPC apoptosis under the condition of increased oxidative stress in angiotensin II (Ang II)-induced hypertension. The results showed that stimulation with 10(-6)mol/L Ang II significantly up-regulated the endogenous ClC-3 expression and increased intracellular reactive oxygen species (ROS) generation in EPCs of wild type mice, accompanied by an enhanced NADPH oxidase activity and the expression of gp91(phox) (NOX-2), a key catalytic subunit of NADPH oxidase. However, these effects of Ang II were significantly reduced in EPCs of ClC-3(-/-) mice. Compared with control, treatment with Ang II induced EPCs apoptosis in wild type mice, concomitantly with declined Bcl-2/Bax ratio, depressed mitochondrial membrane potential and activation of poly(ADP-ribose) polymerase, which was remarkably prevented by both ClC-3 knockout and NADPH oxidase inhibitor apocynin. In addition, the role of ClC-3 deficiency in protecting EPCs against Ang II-induced oxidative stress and apoptosis was further confirmed in Ang II-infused hypertensive mice in vivo. In conclusion, ClC-3 deficiency inhibited Ang II-induced EPC apoptosis via suppressing ROS generation derived from NADPH oxidase.
内皮祖细胞（EPCs）在组织缺血和内皮损伤后参与血管新生和再内皮化。有报道称，高血压时循环 EPCs 数量减少。然而，其详细机制尚不清楚。我们之前的研究表明，ClC-3 氯离子通道在高血压的发展过程中上调。本研究旨在检测 ClC-3 是否参与血管紧张素 II（Ang II）诱导的高血压中氧化应激增加时 EPC 的凋亡。结果显示，10(-6)mol/L Ang II 刺激可显著上调野生型小鼠 EPC 中的内源性 ClC-3 表达，并增加细胞内活性氧（ROS）的产生，同时 NADPH 氧化酶活性和 gp91(phox)（NOX-2）表达增强，后者是 NADPH 氧化酶的关键催化亚基。然而，这些 Ang II 的作用在 ClC-3(-/-)小鼠的 EPC 中明显减弱。与对照组相比，Ang II 处理可诱导野生型小鼠 EPC 凋亡，同时 Bcl-2/Bax 比值降低，线粒体膜电位降低，多聚（ADP-核糖）聚合酶激活，ClC-3 敲除和 NADPH 氧化酶抑制剂 apocynin 均可显著预防这些作用。此外，ClC-3 缺乏在体内 Ang II 输注性高血压小鼠中对 EPCs 对抗 Ang II 诱导的氧化应激和凋亡的保护作用也得到了进一步证实。总之，ClC-3 缺乏通过抑制 NADPH 氧化酶产生的 ROS 抑制 Ang II 诱导的 EPC 凋亡。
