Characterization of X-linked RNA Transcripts in Matured Bovine Spermatozoa

Although the function and utility of RNA transcripts derived from matured spermatozoa remains unclear, they might play important roles in the establishment of a paternal genome and subsequently embryo development. Herein, we investigated the expression of X-chromosome linked RNA transcripts in matured bovine spermatozoa. The total RNA was extracted from the matured spermatozoa, and then converted to cDNA. Autosomal genes (ACT-${\beta}$ and H-2A) and X-chromosome linked genes (ANT3, HPRT, MeCP2, RPS4X, XIAP, XIST and ZFX) were analyzed for the characterization of X-chromosome linked RNA transcripts and compared to female fibroblasts by RT-PCR. The transcripts of autosomal genes (ACT-${\beta}$ and H2A) and X-chromosome linked genes (ANT3, HPRT, MeCP2, RPS4X and ZFX) were not detected in spermatozoa. However, XIAP (X-linked inhibitor of apoptosis protein) and XIST (X-chromosome inactive-specific transcript, a kind of paternal imprinted gene) transcripts were detected in spermatozoa, and relative levels of XIAP and XIST transcripts were similar and 0.5-fold lower when compared to female fibroblasts, respectively. Based on the findings, it is summarized that the presence of RNA transcripts of XIAP and XIST in the isolated spermatozoa may imply their role in inhibition of apoptosis and induction of X-chromosome inactivation in embryo development.