Abstract
Insulin and moderate oxidative stress stimulate proliferation of ovarian theca-interstitial cells. The effects of these agents on selected signal transduction pathways were examined. PD98059 (inhibitor of MAP2K1, also known as MEK-1, upstream of extracellular signal-regulated protein kinases MAPK3/1, also known as ERK1/2), wortmannin (inhibitor of PIK3C2A, also known as PI3K), and rapamycin (inhibitor of FRAP1, also known as mTOR, upstream of RPS6KB1) each significantly decreased insulin and oxidative stress-induced proliferation of theca-interstitial cells. The greatest inhibition was observed in the presence of rapamycin; this effect occurred without a significant change in cell viability. Phosphorylation of AKT was stimulated by insulin only, while phosphorylation of MAPK3/1 and RPS6KB1 was increased by insulin and oxidative stress. Insulin-induced and oxidative stress-induced phosphorylation of RPS6KB1 was partly inhibited by wortmannin and partly by PD98059; the greatest inhibition was observed in the presence of a combination of wortmannin plus PD98059. Effects of insulin and oxidative stress on phosphorylation of RPS6KB1 were confirmed by kinase activity assays. These findings indicate that actions of insulin and oxidative stress converge on MAPK3/1 and RPS6KB1. Furthermore, we speculate that activation of RPS6KB1 may be in part induced via the MAPK3/1 pathway.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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Androstadienes / pharmacology
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Animals
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Carrier Proteins / antagonists & inhibitors
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Carrier Proteins / physiology
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Cell Proliferation*
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Cell Survival / drug effects
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Cell Survival / physiology
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Cells, Cultured
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Female
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Flavonoids / pharmacology
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Hydrogen Peroxide / pharmacology
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Hypoxanthine / pharmacology
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Insulin / pharmacology*
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Mitogen-Activated Protein Kinase 3 / antagonists & inhibitors
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Mitogen-Activated Protein Kinase 3 / metabolism
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Oxidative Stress / physiology*
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Phosphatidylinositol 3-Kinases / metabolism
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Phosphoinositide-3 Kinase Inhibitors
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Phosphorylation / drug effects
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Phosphotransferases (Alcohol Group Acceptor) / antagonists & inhibitors
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Phosphotransferases (Alcohol Group Acceptor) / physiology
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Proto-Oncogene Proteins c-akt / metabolism
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Rats
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Rats, Sprague-Dawley
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Ribosomal Protein S6 Kinases, 70-kDa / metabolism
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Signal Transduction / drug effects
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Signal Transduction / physiology*
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Sirolimus / pharmacology
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TOR Serine-Threonine Kinases
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Theca Cells / cytology
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Theca Cells / drug effects
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Theca Cells / physiology*
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Wortmannin
Substances
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Androstadienes
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Carrier Proteins
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Flavonoids
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Insulin
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Phosphoinositide-3 Kinase Inhibitors
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Hypoxanthine
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Hydrogen Peroxide
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Phosphotransferases (Alcohol Group Acceptor)
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mTOR protein, rat
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Proto-Oncogene Proteins c-akt
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Ribosomal Protein S6 Kinases, 70-kDa
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TOR Serine-Threonine Kinases
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ribosomal protein S6 kinase, 70kD, polypeptide 1
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Mitogen-Activated Protein Kinase 3
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2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
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Sirolimus
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Wortmannin