Expression and Localization of Pannexin Isoforms in Mouse Gonadal Tissues

Pannexin (PANX) channels are large-pore membrane proteins that facilitate ATP release and intercellular signalling, playing essential roles in tissue homeostasis and development. Despite increasing evidence of their involvement in various physiological processes, their distribution and potential functions in mammalian reproductive tissues remain poorly characterized. The aim of this study was to investigate the mRNA expression and protein localization of PANX2 and PANX3 in mouse ovarian tissue, and of PANX1, PANX2 and PANX3 in mouse testicular tissue using immunohistochemistry and quantitative real-time PCR (qRT-PCR). Immunohistochemical analysis revealed distinct isoform- and cell-specific expression patterns. In ovarian follicles, PANX2 expression was predominantly cytoplasmic, whereas PANX3 showed cytoplasmic localization in oocytes and was particularly pronounced in granulosa and cumulus cells of secondary and tertiary follicles. PANX2 protein expression was higher than that of PANX3 in ovarian tissue, while no significant difference was observed at the mRNA level. In the testis, PANX1 and PANX2 were mainly cytoplasmic in spermatogenic cells, whereas PANX3 exhibited both cytoplasmic and membranous localization in spermatogenic, peritubular, and endothelial cells. qRT-PCR analysis revealed no significant differences in mRNA expression levels among the three pannexins. In conclusion, the present study characterizes the localization patterns of pannexin isoforms in mouse ovarian and testicular tissues and provides descriptive data regarding their distribution in different gonadal cell populations.