The Autophagic Interaction Between p97/VCP and ABP Protein Expressions in Sertoli Cell Line: the Effects of Chloroquine and Rapamycin.

Sertoli cells play a pivotal role in spermatogenesis by providing structural support and delivering essential nutrients and signaling molecules to developing germ cells. A key function of these cells is the regulation of androgen-binding protein (ABP), which maintains the high intratesticular testosterone levels necessary for proper spermatogenic progression. Despite the critical nature of ABP, the mechanisms underlying its degradation within Sertoli cells remain poorly understood. This study investigates the role of the valosin-containing protein (p97/VCP) in the autophagic degradation of ABP, with a particular focus on molecular pathways that may contribute to male infertility and testicular dysfunction. Sertoli 15P-1 cells were treated with testosterone, chloroquine, and rapamycin, and subjected to single and double immunofluorescence staining, Western blotting, and siRNA-mediated knockdown experiments to explore the interaction between p97/VCP and ABP. Western blot analysis demonstrated that p62 expression was highest in the chloroquine + testosterone (CQ + T) group compared to control siRNA (Csi), although not statistically significant (p > 0.05). LC3 expression peaked in the chloroquine (CQ) group (p > 0.05). As expected, the lowest expression of p97/VCP was detected in the VCPsi group following siRNA transfection. Immunofluorescence analyses revealed significant differences in protein colocalization patterns across all treatment groups, except for p62 in rapamycin-treated samples. These findings provide the first evidence in the literature of a direct relationship between p97/VCP and ABP within Sertoli cells, underscoring the relevance of autophagic pathways in the regulation of male reproductive hormones. The data suggest a novel regulatory mechanism by which p97/VCP may influence spermatogenesis and male fertility through ABP degradation. Furthermore, this work lays a foundational framework for future investigations in other ABP-expressing tissues such as the brain, liver, and placenta, potentially linking p97/VCP expression to ABP-associated endocrine and pathophysiological disorders beyond the testis.