Follicle-stimulating hormone-dependent phosphorylation of vimentin in cultures of rat Sertoli cells.

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Abstract
Endogenous protein phosphorylation was investigated in cultured rat Sertoli cells after treatment with FSH and pharmacological agents that activate cAMP-dependent protein kinases. In intact Sertoli cells, both phosphorylation and dephosphorylation of proteins occurred in response to treatment with these agents. Studies using cell-free preparations suggest that 4 phosphoproteins phosphorylated by cAMP or the catalytic subunit of cAMP-dependent protein kinase were also phosphorylated in a FSH-dependent manner in intact cells. FSH-dependent phosphorylation in Sertoli cells apparently occurs through activation of a cAMP-dependent protein kinase. A FSH-dependent phosphoprotein with a MW of 58,000 was identified as the intermediate filament protein vimentin, based on its migration in 2-dimensional gels and its peptide map. The cellular distribution of vimentin was monitored by immunofluorescence in Sertoli cells after treatment with FSH. Results support a role for intermediate filaments in FSH-dependent events in Sertoli cells.