Interaction of ARA54 with androgen receptor in mediating testosterone-dependent regulation of caput epididymal GPX5 expression in mice.

Glutathione peroxidase 5 (GPX5), a highly expressed antioxidant enzyme in the caput epididymis, is pivotal for sperm maturation and storage. Exploring its expression regulatory mechanisms is significant for maintaining normal sperm motility, but such mechanisms remain elusive. In this research, we examined the role of androgen receptor (AR) and its co-regulator androgen receptor-associated protein 54 (ARA54) in testosterone-mediated regulation of epididymal GPX5 expression using in vivo and in vitro models. The results indicated that in the castrated mouse model, epididymal expression of GPX5, AR, and ARA54 proteins was markedly downregulated following testosterone deprivation. Exogenous testosterone supplementation restored their expression to near-normal levels. Cellular experiments confirmed the positive regulation of these proteins by testosterone. Mechanistically, AR knockdown not only reduced ARA54 protein levels but also suppressed GPX5 transcription and translation. Similarly, ARA54 knockdown downregulated both mRNA and protein expression of GPX5. Our present study elucidated that ARA54 acts in concert with the AR to mediate the testosterone-induced upregulation of GPX5, offering novel insights for a deeper understanding of the hormonal regulatory network governing the antioxidant microenvironment in the epididymis.