Human granulosa and thecal cells secrete distinct protein profiles

Granulosa and thecal cells were isolated from follicles of ovaries removed from premenopausal women who underwent salpingo-oophorectomy. The electrophoretic profiles of the [35S]methionine-radiolabeled proteins secreted by the two cell types were quite distinct and showed different major proteins. Untreated granulosa cells secreted a major radiolabeled protein with a molecular weight of 220,000, identified as fibronectin by immunoprecipitation. This protein comprised 21% of the total secreted protein; however, the intensity of labeling was reduced after treatment with 0.5 mM dibutyryladenosine 3':5'-cyclic monophosphate ([Bu]2 cAMP). Fibronectin secretion by control cultures measured by a competitive enzyme-linked immunoadsorbant assay ranged from 15.1 to 16.8 micrograms/mg cellular protein/24 hours and was reduced to 30% after treatment with 0.5 mM (Bu)2 cAMP. In contrast, untreated thecal cells secreted only low levels of fibronectin and a 25,000-dalton protein contributed 20% of the total secreted radiolabeled proteins.