NUCB2/nesfatin-1 suppresses the acrosome reaction in sperm within the mouse epididymis

다국어 초록 (Multilingual Abstract)

Nesfatin-1, a polypeptide hormone derived from the nucleobindin 2 (NUCB2) precursor protein, isknown to regulate appetite and energy metabolism. Recent studies have also shown that NUCB2/nesfatin-1 is expressed in the reproductive organs of mice. However, the expression and potentialrole of NUCB2/nesfatin-1 in the mouse epididymis remain unclear. Therefore, we investigated theexpression of NUCB2/nesfatin-1 in the mouse epididymis and its potential function. NUCB2/nesfatin-1 was detected in the epididymis by qRT-PCR and western blotting, and highexpression levels were observed in epididymal epithelial cells by immunohistochemical staining.
Pregnant mare’s serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG)injections significantly increased NUCB2/nesfatin-1 expression in the epididymis. Aftercastration, NUCB2/nesfatin-1 expression in the epididymis decreased, but was significantlyincreased by testosterone injection. Nesfatin-1-binding sites were found in the middle piece oftesticular sperm, but were scarcely detected in the sperm head. By contrast, nesfatin-1 bindingsites were identified on the sperm head within the epididymis. Furthermore, nesfatin-1treatment inhibited the acrosome reaction in epididymal sperm. These results suggest that thenesfatin-1 protein produced in the epididymis binds to nesfatin-1 binding sites on the spermhead and plays a role in suppressing the acrosome reaction before ejaculation.