Porcine SRY Promoter Is a Target for Steroidogenic

To study the process of mammalian sex determination and in particular to further understand the mechanisms of transcrip-tional regulation of the SRY gene, we have isolated a 4.5-kilo-base (kb) pig SRY 59 flanking sequence. To facilitate the in vitro analysis of these sequences, we have generated a porcine genital ridge (PGR) cell line (9E11) that expresses SRY as well as SOX9, steroidogenic factor-1 (SF-1), and DAX1. Via primer extension analysis on RNA from this cell line, a transcription start site for porcine SRY was identified at 2661 base pairs (bps) 59 from the translation initiation site. Deletion studies of the SRY 59 flanking sequences in PGR 9E11 cells demonstrated that 21.4 kb of 59 flanking sequences retained full transcriptional activity com-pared with the 24.5 kb fragment, but that transcriptional activ-ity fell when further deletions were made. Sequences down