Asprosin regulates male reproduction in teleosts: an in vitro study in Channa punctata

The novel adipokine asprosin, produced by the furin enzymatic cleavage of profibrillin 1 protein (encoded by the Fbn1 gene), is implicated in regulating many physiological functions, including reproduction in mammals. In males, asprosin is reported to increase sperm density, sperm motility, and steroid production by interacting with Olfr734, which belongs to the G-protein-coupled receptor family (GPCR). In 2023, our group predicted and characterized asprosin in silico for the first time and demonstrated the robust expression of fbn1, and furin in the gonads of teleost spotted snakehead (ss) Channa punctata. Taking it forward, in the current study, we have investigated the effect of asprosin on the testicular functions of the spotted snakehead. As C. punctata is a seasonal breeder, the reproductive-phase-dependent expression of fbn1 in the testis was analyzed, showing significant upregulation during the preparatory and post-spawning phases. Additionally, bacterially overexpressed recombinant asprosin of C. punctata was purified to study the effect of ss asprosin on gametogenesis and steroidogenesis. Ex vivo treatment with recombinant asprosin resulted in significant upregulation of spermatogenic marker genes pcna, aldh1a2, cyp26a1, and sycp3. Asprosin also enhanced the gene expression of gonadotropin receptors, as well as sex steroid receptors, in addition to steroidogenic genes star and cyp17a1. Further exploring the downstream signaling cascade, the second messenger of GPCRs, cAMP levels following asprosin treatment were analyzed. Asprosin treatment prominently enhanced cAMP levels, thereby indicating the involvement of GPCR in the transduction of asprosin action. Hence, the study elucidates the regulation of male reproductive function by asprosin in spotted snakeheads.