Sertolin: a novel molecule to study Sertoli-germ cell interactions in the testis

A novel testicular gene designated sertolin was isolated and cloned by the sequential use of mRNA differential display and PCR. The isolated full-leng th sertolin cDNA clone has 853 bp with an open reading frame of 381 bp codi ng for a 127-amino acid polypeptide (calculated M-r 13,759 Da). Sertolin sh ares limited homologies with antaxin/josephin and thrombospondin proteins. Sertolin has two mRNA transcripts of 2.3 and 1 kb. Immunoblot analysis dete cted a 17 kDa immunoreactive protein in the Sertoli cell cytosol but not in the spent media. No changes in sertolin expression were detected in Sertol i cells cultured alone when specialized inter-Sertoli cell junctions were b eing formed. However, a transient but drastic reduction of about 5-fold in sertolin expression was detected at 3-4 hr when germ cells were cocultured with Sertoli cells at the time preceding the formation of specialized Serto li-germ cell junctions. Furthermore, IL-1 alpha was able to regulate Sertol i cell sertolin expression in vitro. These results illustrate that sertolin is a promising molecule to study cell-cell interactions in the testis.