| Recently, a novel family of gap junction (GJ) proteins, the pannexins (Panxs), has been identified in vertebrates. To evaluate the role of Panxs in the male reproductive tract (MRT), we investigated the expression and distribution of Panx1 and Panx3 in the testis, efferent ducts (EDs), and epididymis of adult rats. In the testis, Panx1 localized to Sertoli cells in the basal compartment of seminiferous epithelium, while Panx3 was expressed in Leydig cells. In the EDs, both Panx1 and Panx3 were expressed in the epithelium, notably at the apical region of ciliated cells. In the epididymis, both Panxs were expressed in principal cells. Prominent labelling for Panx1 was also observed laterally and basally between adjacent principal cells and at the interface between principal and basal cells. Panx3 was noted apically in principal cells and at the plasma membrane of halo cells. RT-PCR and Western blots analyses confirmed the expression of both Panxs in the MRT, with multiple species being detected in western blots and observed to be expressed in a region-specific manner, corroborating previous reports of post-translational glycosylation of Panxs. Preliminary RT-PCR results suggested that Panx1 may be regulated at the mRNA level since alternative splicing may account for some of these species. Testosterone and other testicular factors appear to regulate expression of Panxs, as an increase in the number of Panx1 species and a change in the expression of Panx3 species were observed with orchidectomy, and these were partially inhibited by testosterone supplementation. In conclusion, Panxs are present throughout the MRT where they are expressed in a cell type- and region-specific manner and appear to be regulated in terms of expression levels, subcellular localization and post-translational modification. Taken together their wide spread distribution suggest an important role for Panxs in the MRT. |
