Transforming growth factor-beta (TGF-b) induced phosphorylation of the myristoylated alanine rich C kinase substrate (MARCKS) protein in ovarian granulosa cells is modulated by follicle stimulating hormone (FSH).
The mechanism by which TGF-b1 affects granulosa cell physiology as well as the modulation of TGF-b1 activity by FSH are not understood. We tested the hypothesis that TGF-b1 exerts its effects on granulosa cells via activation of protein kinase C (PKC). Immunoprecipitation of the MARCKS protein from 32P labeled rat granulosa cells was used to assay PKC activation. 20 minute treatment with TGF-b1 (8 ng/ml), forskolin (30 microM), and TPA (200 nM) all caused an increase in MARCKS phosphorylation as quantified by densitometric scanning. FSH did not increase MARCKS phosphorylation above control levels while exposure of cells to both FSH and TGF-b1 (10 ng/ml) decreased phosphorylation of the MARCKS protein to control levels. These data suggests that (1) TGF-b1 signal transduction in rat granulosa cells may partially involve phosphorylation of the MARCKS protein; and, (2) in granulosa cells FSH can modulate TGF-b1 induced MARCKS phosphorylation.
Pennybacker
M
M
Department of Cell Biology and Anatomy, School of Medicine, University of North Carolina, Chapel Hill 27599-7090.
Herman
B
B
D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005640:Follicle Stimulating Hormone / Q000502:physiology*; D006107:Granulosa Cells / Q000378:metabolism*; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors* / Q000502:physiology*
D047908:Intracellular Signaling Peptides and Proteins; C000619712:Marcks protein, rat; D008565:Membrane Proteins; D011506:Proteins; D016212:Transforming Growth Factor beta; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D005576:Colforsin; D005640:Follicle Stimulating Hormone; D000242:Cyclic AMP; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate