FOLLICLE-STIMULATING-HORMONE INCREASES THE EXPRESSION OF TISSUE INHIBITORS OF METALLOPROTEINASES TIMP-1 AND TIMP-2 AND INDUCES TIMP-1 AP-1 SITE BINDING COMPLEX(ES) IN PREPUBERTAL RAT SERTOLI CELLS

Primary cultures of prepubertal rat Sertoli cells secrete two major ti ssue inhibitors of metalloproteinases: TIMP-1 (M(r) 28 K) and TIMP-2 ( M(r) 21 K). FSH stimulated Sertoli cell TIMP-1 and TIMP-2 activity in a time- and dose-dependent manner and also stimulated TIMP-1 and TIMP- 2 protein and messenger RNA levels. These effects were mimicked by the cAMP analog, 8-bromo-cAMP, and the phosphodiesterase inhibitor 3-isob utyl-1-methylxanthine. The protein kinase C activating phorbol ester p horbol myristrate acetate (TPA) stimulated TIMP-1 but not TIMP-2 activ ity and messenger RNA levels. Cycloheximide and actinomycin-D inhibite d basal TIMP-1 and TIMP-2 activity and inhibited the ability of FSH, 8 -bromo-cAMP, and TPA to stimulate TIMP activity. The protein kinase A (PKA) inhibitor AMP Rp isomer did not affect basal TIMP-1 and TIMP-2 a ctivity or TPA-stimulated TIMP-1 activity. However, the PKA inhibitor markedly reduced FSH and 3-isobutyl-1-methylxanthine stimulation of TI MP-1 and TIMP-2 activity. FSH, 8-bromo-cAMP, and TPA stimuli induced D NA binding complexes capable of binding to a TIMP-1 AP-1 site consensu s sequence oligonucleotide. The AP-1 site binding complex(es) induced by all three treatments reacted with antibodies directed broadly again st fos and jun protooncogene families and against the specific family members c-fos, junB, and junD but not c-jun proteins. Constitutive cAM P response element binding activity capable of binding an artificial c AMP response element binding site oligonucleotide was demonstrated in Sertoli cell nuclear extracts. This activity was minimally modulated b y FSH, 8-bromo-cAMP, or TPA treatment. In summary, Sertoli cells secre te TIMP-1 and TIMP-2 that can be coordinately up-regulated by FSH thro ugh a cAMP, PKA-dependent pathway. A convergence-of TPA, FSH, and cAMP mediated signals in prepubertal Sertoli cells may occur with the indu ction of specific AP-1 site binding complex(es) containing jun and fos proteins. Our data suggest that FSH stimulation of TIMP-2 expression may be regulated independently to that of TIMP-1. We propose that the ability of FSH to stimulate Sertoli cell TIMP activity suggests a cent ral role for this hormone in the control of extracellular matrix turno ver during testicular development at the level of metalloproteinase in hibition.