SRY PROTEIN ENHANCES TRANSCRIPTION OF FOS-RELATED ANTIGEN-1 PROMOTER CONSTRUCTS

In mammals, testis determination is under the control of the chromosom e Y-linked SRY gene. Sry is expressed in the fetal mouse just before d evelopment of the testis and shows germ-cell-dependent expression in t he adult mouse. SRY protein contains a high-mobility-group (HMG)-box D NA-binding domain, and potential target sequences have been identified . The fos-related antigen 1 (fra-1) gene is closely related to the pro tooncogene c-fos and encodes a component of transcription factor AP-1. Fra-1 is expressed during spermatogenesis, and the promoter of the ra t fra-1 gene contains several potential binding sites for members of t he HMG-box family of DNA-binding proteins. We demonstrate that purifie d SRY protein binds strongly to one of the putative fra-1 HMG-box resp onse elements and that SRY enhances the transcription of rat fra-1 pro moter constructs in cotransfection experiments. These results suggest that the function of HMG-box transcription factors may be mediated, in part, by activation of members of the AP-1 transcription factor famil y.