Signal Transduction in Avian Granulosa Cells: Effects of Protein Kinase C Inhibitors

M. Jamaluddin, M. Molnár, B. L. Marrone, F. Hertelendy

Research output: Contribution to journalArticle

10 Scopus citations

Abstract

We evaluated the effects of two protein kinase C (PKC) inhibitors, staurosporine (ST) and H-7, on LH-activated phospholipase C and adenylate cyclase activity by measuring the production of inositol phosphates (IP) and cAMP in freshly dispersed granulosa cells from mature preovulatory follicles of laying hens. ST and H-7 dose-dependently potentiated LH-stimulated IP generation, whereas a protein kinase A (PKA) inhibitor (H-8) had no effect. The PKC activator, phorbol ester TPA (50 nM), significantly inhibited LH-stimulated IP production, which was completely prevented by ST. Both ST and H-7, while having no effect on basal cAMP levels, significantly and dose-dependently potentiated LH-stimulated, but not forskolin-stimulated cAMP production. However, progesterone production in response to LH, forskolin, and 8-Br-cAMP was inhibited in granulosa cells proincubated for 30 min with H-7 or ST. H-7 and ST had no effect on 25-hydroxycholesterol- and pregnenolone-supported progesterone production. These results support a negative feedback role for PKC in LH-initiated signal transduction in avian granulosa cells. PKC blockade removes the inhibitory effect on LH-stimulated phospholipase C and adenylate cyclase activity. The inhibitory effect of H-7 and ST on progesterone synthesis could be attributed to inhibition of PKA and/or steps proximal to cholesterol side-chain cleavage.

Original languageEnglish (US)
Pages (from-to)471-479
Number of pages9
JournalGeneral and Comparative Endocrinology
Volume93
Issue number3
DOIs
StatePublished - Mar 1994

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology

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