Involvement of PI3 kinase and MAP kinase in IGF-I- and insulin-induced oocyte maturation in Cyprinus carpio.
Previously, we observed that in vitro germinal vesicle breakdown (GVBD) in Cyprinus carpio oocytes was induced by recombinant human insulin-like growth factor-I (IGF-I) and bovine insulin (b-insulin) and this induction was steroid-independent. To investigate further the early signal transduction components involved in this process, the possible role of phosphatidylinositol 3-kinase (PI3 kinase) during oocyte maturation was examined. IGF-I- and b-insulin-induced oocyte maturation was significantly inhibited by Wortmannin and LY294002, two mechanistically different specific inhibitors of PI3 kinase. IGF-I and b-insulin were shown to activate PI3 kinase after 90 min of their treatment. Both IGF-I and b-insulin were found to activate cdc2 kinase at 21h of treatment. We examined the relative involvement of PI3 kinase, MAP kinase and cdc2 kinase in IGF-I- and b-insulin-induced oocyte maturation in C. carpio. MAP kinase was rapidly phosphorylated and activated (30-150 min) in response to exposure of the oocytes with IGF-I and b-insulin. This response preceded the phosphorylation and activation of cdc2 by several hours (almost 19h). A potent and selective inhibitor of MEK, PD98059, the protein kinase that phosphorylates and activate MAP kinase, blocked the phosphorylation and activation of MAP kinase and cdc2 kinase and GVBD induction. Likewise, PI3 kinase inhibitors strongly inhibited phosphorylation and activation of MAP kinase, which was increased during oocyte maturation. Taken together, these results suggest that PI3 kinase is an initial component of the signal transduction pathway which precedes MAP kinase, and MPF activation during IGF-I- and b-insulin-induced oocyte maturation in C. carpio.
Paul
Sudipta
S
Endocrinology Laboratory, Department of Zoology, University of Kalyani, Kalyani 741235, West Bengal, India.
Pramanick
Kousik
K
Kundu
Sourav
S
Bandyopadhyay
Arun
A
Mukherjee
Dilip
D
D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D002347:Carps / Q000378:metabolism*; D002417:Cattle; D002454:Cell Differentiation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology*; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D013997:Time Factors
D016203:CDC2 Protein Kinase; D048049:Extracellular Signal-Regulated MAP Kinases; D007328:Insulin; D007334:Insulin-Like Growth Factor I; D020928:Mitogen-Activated Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D047428:Protein Kinase Inhibitors