CoCl₂-simulated hypoxia in skeletal muscle cell lines: Role of free radicals in gene up-regulation and induction of apoptosis

Abstract

Since it was suggested that cobalt chloride (CoCl₂) could mimic the O₂ sensing role of mitochondria by increasing reactive oxygen species (ROS) generation during normoxia, we studied the correlation between CoCl₂-generation of free radicals and the induction of a hypoxic cellular response in myogenic cell lines. In both L6C5 and C2C12 cell lines, exposure to CoCl₂ induced an increase of intracellular oxidants, the accumulation of HIF-1α protein, and the expression of vascular endothelial growth factor (VEGF) and/or iNOS genes. On the other hand, only ascorbic acid, but not trolox, was effective in lowering the CoCl₂ gene up-regulation. Neither the cytotoxicity nor the apoptosis induced by CoCl₂ in skeletal muscle cells were modified by culture supplementation with either ascorbic acid or trolox. Thus, CoCl₂ treatment of myogenic cell lines may represent a useful and convenient in vitro model to study gene modulation induced by hypoxia in skeletal muscle, although cellular loss induced by this metal may involve mechanisms other than HIF-1α stabilization. It is unlikely, however, that ROS would represent the main mediators of CoCl₂ effects on muscle cells.

• CoCl₂
• ROS
• skeletal muscle cells
• gene expression
• apoptosis