SERTOLI-CELL DIFFERENTIATION ON BASEMENT-MEMBRANE IS MEDIATED BY THE C-FOS PROTOONCOGENE

When Sertoli cells of the seminiferous epithelium in the testis were c ultured on Matrigel (a reconstituted basement membrane), laminin, or o ne of the biologically active laminin-derived peptides (YIGSR, SIKVAV, of RGD), they exhibited dramatic changes in morphology accompanied by changes in protein secretion and gene expression, including a rapidly induced stimulation of c-fos mRNA. TO examine the role of c-fos in Se rtoli cell attachment, spreading, and differentiation on extracellular matrix, we constructed sense and antisense c-fos phosphorothioate oli godeoxynucleotides (ODNs). Sertoli cells, in small clumps of 10-20 cel ls, cultured on Matrigel or laminin in the presence of ODNs antisense to c-fos (30 mu g/ml) did not spread for the first 10-20 hr. After tha t time, normal spreading occurred, probably as a result of ODN degrada tion. Cells cultured in medium supplemented with ODNs sense to c-fos ( 30 mu g/ml), or without ODNs, spread within 30 min to 1 hr, and after 12 hr a monolayer was established. Furthermore, incubation of Sertoli cells with ODNs antisense to c-fos resulted in a significant reduction of c-fos protein levels, whereas treatment with ODNs sense to c-fos b arely affected c-fos protein expression. These data indicate that c-fo s may mediate the events involved in Sertoli cell attachment and sprea ding upon contact of the cells with extracellular matrix.