Mitochondrial reactive oxygen species and c-Src play a critical role in hypoxic response in vascular smooth muscle cells

• Published in: Cardiovascular research 2005-09, Vol.67 (4), p.714-722
• Main Authors: SATO, Hiroko, SATO, Mahito, KANAI, Hiroyoshi, UCHIYAMA, Tsuyoshi, ISO, Tatsuya, OHYAMA, Yoshio, SAKAMOTO, Hironosuke, TAMURA, Junichi, NAGAI, Ryozo, KURABAYASHI, Masahiko
• Format: Article
• Language: English
• Subjects: Androstadienes - pharmacology; Animals; Atherosclerosis (general aspects, experimental research); Biological and medical sciences; Blood and lymphatic vessels; Blotting, Northern; Cardiology. Vascular system; Catalase - pharmacology; Cell Hypoxia; Cell Line; Flavonoids - pharmacology; Hydrogen Peroxide - metabolism; Hypoxia-Inducible Factor 1, alpha Subunit - metabolism; Imidazoles - pharmacology; Immunoblotting; Medical sciences; Microscopy, Fluorescence; Mitochondria - metabolism; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle - metabolism; Naphthalenes - pharmacology; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphorylation; Plasminogen Activator Inhibitor 1 - genetics; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins pp60(c-src) - metabolism; Pyrazoles - pharmacology; Pyridines - pharmacology; Pyrimidines - pharmacology; Rabbits; RNA, Messenger - analysis; Rotenone - pharmacology
• ISSN: 0008-6363; 1755-3245
• DOI: 10.1016/j.cardiores.2005.04.017

Thickened atherosclerotic plaques are prone to be hypoxic because of poor perfusion. In this study, we tested (a) whether reactive oxygen species (ROS) and c-Src play roles in hypoxic induction of HIF-1alpha protein and PAI-1 gene expression in the rabbit aortic smooth muscle cell line C2/2 cells and primary cultures of rat aortic smooth muscle cells, and (b) how mitochondria act on the hypoxia-induced signaling mechanism. Hypoxic exposure of C2/2 cells increased H2O2 generation, c-Src phosphorylation, HIF-1alpha protein expression, and PAI-1 gene expression. Catalase, a scavenger of H2O2, inhibited the hypoxia-induced ROS generation and PAI-1 gene expression. Src kinase inhibitors PP1 and PP2 inhibited hypoxia-induced HIF-1alpha protein and PAI-1 gene expression. Ablation of mitochondrial respiration by rotenone abolished hypoxia-induced ROS generation, c-Src phosphorylation, HIF-1alpha protein expression, and PAI-1 gene expression. Induction of HIF-1alpha protein and PAI-1 gene expression in response to hypoxia was regulated by ROS production and c-Src activation in vascular smooth muscle cells. Mitochondria linked the hypoxic signal to c-Src, which in turn led to HIF-1alpha protein and PAI-1 gene expression. These results provide evidence that hypoxia induces the ROS-mediated and c-Src-dependent signaling cascades which are closely associated with angiogenesis and thrombosis in atherosclerotic vasculature.