A study of Y chromosome gene mRNA in human ejaculated spermatozoa

We asked if messenger ribonucleic acid (mRNA) of Y chromosome genes was selectively retained in human ejaculated spermatozoa. A panel of genes on the nonrecombining region of Y chromosome (NRY) and their X homologues were selected and screened in human testis and ejaculated spermatozoa by reverse transcription-polymerase chain reaction (RT-PCR). Then, the cellular localization of DBY, RPS4Y and SMCY mRNA in testis and matured spermatozoa were investigated by in situ hybridization. The expression pattern of these three genes in human ejaculated spermatozoa was also tested by Western blot and Immunofluorescence. All 11 Y chromosome gene mRNAs were found in the testis, but the transcripts of only three genes DBY, SRY, and RPS4Y were detected in ejaculated sperm by RT-PCR. Further investigation showed that DBY and RPS4Y mRNA were present in both human testis and the post-acrosome region comprising nearly 50% of spermatozoa, while the encoded proteins were not detected in spermatozoa. In contrast, although SMCY mRNA was not detected in mature spermatozoa, the H-Y antigen encoded by SMCY was expressed on the surface of spermatozoa. We therefore conclude that the spermatozoa mRNA could be selectively reserved in mature ejaculated spermatozoa. They might be useful in early zygotic and embryonic development.