FOLLICLE-STIMULATING-HORMONE REGULATION OF AP-1 - INHIBITION OF C-JUNAND STIMULATION OF JUN-B GENE-TRANSCRIPTION IN THE RAT SERTOLI-CELL

The proto-oncogenes c-fos and c-jun and the related jun-B encode the c omponents of transcription factor, AP-1, a heterodimeric DNA-binding p rotein that mediates hormone and growth factor-regulated gene expressi on. In the rat Sertoli cell, FSH rapidly inhibited c-jun gene expressi on while it stimulated c-fos and jun-B as well as the expression of th e more slowly responding, tissue plasminogen activator (tPA) and inhib in alpha-subunit. These early effects of FSH were not inhibited by cyc loheximide. Nuclear run-off analyses demonstrated that the FSH-depende nt decline in c-jun and increases in c-fos, jun-B, tPA and inhibin alp ha-subunit mRNAs were regulated at the transcriptional level. The rate s of degradation of c-fos, c-jun and jun-B mRNAs were unaffected by FS H while tPA and inhibin alpha-subunit mRNAs were stabilized. After 8 h of FSH treatment, the transcription of all five genes returned to bas al rates. These data demonstrate immediate-early regulation by FSH of the expression of genes encoding components of the transcription facto r, AP-1.