MR 03. ERK1/2 are involved in the inhibition of StAR protein expression and testosterone production in Leydig cells

Cox7a2 is the gene encoding one component of the nuclearencoded subunits of cytochrome c oxidase complex in the mitochondrial respiratory chain. Cox7a2 has shown high expression in the testes of aging males, but the significance of such high expression pattern is unclear. In our study, we explored the subcellular localization, its effect on StAR protein expression, and steroidogenesis of Cox7a2 and its interaction with ERK cascade in TM3 mouse Leydig cell by transient gene transfection. The expression pattern of Cox7a2 in normal human organs was also studied. We found that there were different expression characteristics of Cox7a2 in normal human organs. Cox7a2 fusion protein was well located into mitochondria in TM3 mouse Leydig cell. Cox7a2 inhibited testosterone production by decreasing StAR protein expression, which might be at least in part related with the inactivation of ERK1/2 in TM3 mouse Leydig cell.