Cobalt chloride induces PC12 cells apoptosis through reactive oxygen species and accompanied by AP-1 activation

Reactive oxygen species (ROS) are supposed to play an important role in hyp oxia- and ischemia/reperfusion-mediated neuronal injury with the characteri stics of apoptosis, There are many reports showing that cobalt chloride (Co Cl2,) could mimic the hypoxic responses in some aspects including productio n of ROS in cultured cells. The cytotoxicity of CoCl2 and its molecular mec hanisms have yet to be elucidated. We report that CoCl2 triggered neuronal PC12 cells apoptosis in a dose- and time-dependent manner. Apoptosis was de monstrated by morphological changes and DNA fragmentation, and was dependen t on macromolecular synthesis. Apoptosis was also confirmed by the decrease of the expression of Bcl-X-L, To our knowledge, this is the first document ation of the apoptotic induction of CoCl2 on PC12 cells. Furthermore, ROS p roduction in PC12 cells was increased during CoCl2 treatment. Antioxidants, which could inhibit ROS production, significantly blocked CoCl2-induced ap optosis, suggesting that apoptosis is mediated by ROS production. We also o bserved a significant increase of the DNA-binding activity of AP-1 in respo nse to CoCl2 and this increase was blocked by antioxidants, showing that Co Cl2-induced apoptosis is accompanied by ROS-activated AP-1, CoCl2-treated P C12 cells may serve as an in vitro model for studies of molecular mechanism s in ROS-linked neuronal disorders. (C) 2001 Wiley-Liss, Inc.