Expression of the human SRY protein during development in normal male gonadal and sex-reversed tissues

Sex determination in mammals is controlled by the SRY gene located on the Y chromosome. It encodes a protein containing a DNA-binding and DNA-bending domain. In spite of recent advances in the identification of the mechanisms that regulate male sex determination in mammals, the expression profile of the SRY protein in normal and sex-reversed human tissues is not well estab lished. In order to localize the SRY protein and determine its cellular dis tribution and expression at different stages of development, we prepared mo noclonal antibodies (mAb) against the recombinant SRY protein. One of these antibodies, LSRY1.1, recognizes a protein of 27 kDa in total lysates of He La SRYB3, a human cell line transfected with the SRY gene under the control of the SV40 promoter. Immunocytochemical analysis in the cell lines shows nuclear localization of the SRY protein. We have studied SRY protein expres sion in human tissues at different stage of fetal development until adult l ife and have demonstrated that the SRY protein is located in the nuclei of somatic cells and germ cells in the genital ridge during testis development . After testis determination, it can be detected until the adult stage in b oth germ cells and Sertoli cells. The presence of the SRY protein was also analyzed in biopsies of gonadal tissues of sex-reversal patients such as SR Y-positive 46,XX males or SRY-positive 46,XX true hermaphrodites. SRY prote in is detected in the nuclei of Sertoli cells of the testis and in the nucl ei of granulosa cells in the ovotestis in these patients and in the nuclei of germ cells of both tissue types. These results suggest a common cellular origin for both Sertoli cells and granulosa cells. J. Exp. Zool. 290:607-6 15, 2001. (C) 2001 Wiley-Liss, Inc.