Primary cultures of prepubertal rat Sertoli cells secrete two major tissue inhibitors of metalloproteinases: TIMP-1 (M, 28 K) and TIMP-2 (Mr 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-isobutyl-1-methylxanthine. The protein kinase C activating phorbol ester phorbol myristrate acetate (TPA) stimulated TIMP-1 but not TIMP-2 activity and messenger RNA levels. Cycloheximide and actinomycin-D inhibited 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 activity or TPA-stimulated TIMP-1 activity. However, the PKA inhibitor markedly reduced FSH and 3-isobutyl-1-methylxanthine stimulation of TIMP-1 and TIMP-2 activity. FSH, 8-bromo-cAMP, and TPA stimuli induced DNA binding complexes capable of binding to a TIMP-1 AP-1 site consensus sequence oligonucleotide. The AP-1 site binding complex(es) induced by all three treatments reacted with antibodies directed broadly against fos and jun protooncogene families and against the specific family members c-fos, junB, and junD but not c-jun proteins. Constitutive cAMP response element binding activity capable of binding an artificial cAMP response element binding site oligonucleotide was demonstrated in Sertoli cell nuclear extracts. This activity was minimally modulated by FSH, 8-bromo-cAMP, or TPA treatment. In summary, Sertoli cells secrete TIMP-1 and TIMP-2 that can be coordinately up-regulated by FSH through a cAMP, PKA-dependent pathway. A convergence of TPA, FSH, and cAMP mediated signals in prepubertal Sertoli cells may occur with the induction 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 central role for this hormone in the control of extracellular matrix turnover during testicular development at the level of metalloproteinase inhibition.
|Number of pages||9|
|Publication status||Published - Dec 1994|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism