Cytoplasmic malic enzyme and testicular steroidogenesis in mice

The malate shuttle has been hypothesized as a source of the intramitochondrial NADPH required for cholesterol side-chain cleavage. In the present report, the role of the malate shuttle in testicular steroidogenesis was investigated by employing mouse mutants deficient in cytoplasmic malic enzyme, a required component of the shuttle. Androgen-dependent parameters plus testosterone secretion by in vitro perfused testes were similar for the mutants and their normal siblings. The data suggest that an active malate shuttle is not required for cholesterol side-chain cleavage in mouse testes.