Characterization of Xlr5c as a Novel Nuclear

Background Spermatogenesis is the complex process by which diploid stem cells generate haploid germ cells in gamete production. Members of the Xlr (X-chromosome linked, lymphocyte regulated) superfamily play essential roles in spermatogenesis. The expression, localiza-tion and role in spermatogenesis of one such member, Xlr5c, has not been reported previously. Methodology/Principal Findings Xlr5c mRNA and protein levels in murine testes and other tissues were investigated using RT-PCR andWestern blotting. Xlr5c was abundantly transcribed in mouse testes, particularly during the early stages of spermatogenesis and throughout prophase I in the nuclei of spermatocytes. Xlr5c was specifically localized at synaptonemal complexes(SCs) region in preleptotene and pachytene spermatocytes, as was the homologous Xlr protein Sycp3. Conclusions/Significance These results suggest that Xlr5c was abundantly transcribed in germ cells, localized at SCs region, where it may play a potential role during the early stages of spermatogenesis. Identi-fication and characterization of this novel testis protein may offer a new perspective for understanding of the molecular mechanisms involved in germ cell differentiation