Sertoli cell differentiation on basement membrane is mediated by the c-fos protooncogene.

When Sertoli cells of the seminiferous epithelium in the testis were cultured on Matrigel (a reconstituted basement membrane), laminin, or one of the biologically active laminin-derived peptides (YIGSR, SIKVAV, or 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 Sertoli cell attachment, spreading, and differentiation on extracellular matrix, we constructed sense and antisense c-fos phosphorothioate oligodeoxynucleotides (ODNs). Sertoli cells, in small clumps of 10-20 cells, cultured on Matrigel or laminin in the presence of ODNs antisense to c-fos (30 micrograms/ml) did not spread for the first 10-20 hr. After that time, normal spreading occurred, probably as a result of ODN degradation. Cells cultured in medium supplemented with ODNs sense to c-fos (30 micrograms/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 barely affected c-fos protein expression. These data indicate that c-fos may mediate the events involved in Sertoli cell attachment and spreading upon contact of the cells with extracellular matrix.