THE HUMAN SRY TRANSCRIPT

SRY encodes the Y-linked testis-determining factor in humans. A predom inant 900 bp transcript originates from a single exon and encompasses the putative SRY coding sequence. We show that in human adult testis S RY transcription involves multiple start sites. In addition to a previ ously defined major initiation site, transcripts originating at least 410 bp upstream of this site were detected. Using a cDNA specific RT-P CR assay, embryonic and adult human tissues were screened for SRY expr ession. In humans, SRY transcription is not restricted to the presumpt ive and the mature gonadal tissues in the embryo and the adult respect ively but can be detected in a range of other locations. Two human cel l lines, NTERA-2 cl.D1 (NT2/D1) and Hep G2, have been identified which express SRY at similar levels to adult testis. The NT2/D1 SRY transcr ipts appear to have the same structure as those in adult testis. HMBA- induced differentiation of NT2/D1 cells results in a diminution of SRY mRNA, while transcription of SRY in retinoic acid differentiated NT2/ D1 is unaffected.