SRY protein enhances transcription of Fos-related antigen 1 promoter constructs.

In mammals, testis determination is under the control of the chromosome Y-linked SRY gene. Sry is expressed in the fetal mouse just before development of the testis and shows germ-cell-dependent expression in the adult mouse. SRY protein contains a high-mobility-group (HMG)-box DNA-binding domain, and potential target sequences have been identified. The fos-related antigen 1 (fra-1) gene is closely related to the protooncogene c-fos and encodes a component of transcription factor AP-1. Fra-1 is expressed during spermatogenesis, and the promoter of the rat fra-1 gene contains several potential binding sites for members of the HMG-box family of DNA-binding proteins. We demonstrate that purified SRY protein binds strongly to one of the putative fra-1 HMG-box response elements and that SRY enhances the transcription of rat fra-1 promoter 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 family.