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.