ERO1α promotes testosterone secretion in hCG-stimulated mouse Leydig cells via activation of the PI3K/AKT/mTOR signaling pathway.

ER oxidoreduclin 1 alpha (ERO1 alpha) is an oxidase, participating in formation of secretory and membrane proteins. However, the other physiological functions ERO1 alpha is not well known. We found that ERO1 alpha is high in the Leydig cells of the testis. Therefore, the purposes of the current study are to explore the role of ERO1 alpha and the possible mechanisms in regulating cell proliferation, apoptosis, and testosterone secretion of Leydig cells. ERO1 alpha was mainly localized in Leydig cells in the adult mice testes by immunofluorescence staining. Western blot analysis showed that ERO1 alpha was higher in Leydig cells than that in the seminiferous tubules. The effect of ERO1 alpha on cell proliferation, apoptosis, and testosterone secretion was detected by transducing ERO1 alpha overexpression and knockdown lentiviruses into cultured primary Leydig cells (PLCs) together with hCG exposure. Flow cytometry analysis showed that ERO1 alpha promoted cell proliferation by increasing cell distribution at the S phase and decreasing that at the G0/G1 phase. Western bolt analysis showed that ERO1 alpha increased CDK2 and CDK6 expression. Cell apoptosis determination found that ERO1 alpha inhibited PLC apoptosis. Western bolt analysis showed that ERO1 alpha increased the ratio of BCL-2/BAX, and decreased BAD and Caspase-3 expression. Enzyme-linked immunosorbent assay analysis demonstrated that ERO1 alpha enhanced testosterone secretion. Western bolt analysis found that ERO1 alpha increased StAR, 3 beta-HSD, and CYP17A1 expression. Furthermore, ERO1 alpha could activate the PI3K/AKT/mTOR signaling pathway. In summary, these results suggest that ERO1 alpha might play proliferation promotion and antiapoptotic roles and enhance testosterone secretion in PLC, at least partly, via activation of the PI3K/AKT/mTOR signaling pathway.