Participation of PI3-kinase/Akt signalling in insulin stimulation of p34cdc2 activation in zebrafish oocyte: Phosphodiesterase 3 as a potential downstream target

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• 作者：Debabrata Das ; Pragya Paramita Khan ; Sudipta Maitra ; ^{smaitra3@gmail.com} ; ^{sudipta.maitra@visva-bharati.ac.in}
• 关键词：Insulin signalling ; PI3K ; Akt ; Phosphodiesterase ; Oocyte maturation ; Zebrafish
• 刊名：Molecular and Cellular Endocrinology
• 出版年：2013
• 出版时间：15 July, 2013
• 年：2013
• 卷：374
• 期：1-2
• 页码：46-55
• 全文大小：1592 K

文摘

Exposure of fully grown oocytes to growth factors (insulin/IGFs) initiates various signalling cascades that culminate to final stages of oocyte maturation. Regulation of signalling pathways during growth factor-induced meiosis resumption in fish is not well characterized. Here we studied the participation of PI3K/Akt signalling pathway during recombinant human insulin (rh-insulin)-induced meiotic maturation in zebrafish (Danio rerio) oocytes. Priming of defolliculated oocytes in vitro with rh-insulin promotes germinal vesicle breakdown (GVBD) in a dose- and time-dependent manner, an effect sensitive to translation but not transcription inhibition. More than 80 % of the oocytes underwent GVBD due to 0.8 IU/ml rh-insulin within 10 h of incubation and the kinetics of p34cdc2 kinase activation corresponded well with GVBD data. PI3K inhibitors, wortmannin and LY294002 blocked insulin, but not 17¦Á, 20¦Â-DHP-induced GVBD. Immunoblot analyses of oocyte extract revealed that phospho-PI3K (p85¦Á) was up regulated within 30-60 min of insulin stimulation followed by phospho-Akt (Ser473) at 60-120 min. Though PI3K/Akt phosphorylation was largely unaffected, pre-incubation with phosphodiesterase (PDE) inhibitors, IBMX and cilostamide, but not rolipram completely blocked rh-insulin-induced p34cdc2 activation and GVBD. These results suggest that PDE3 may be one potential downstream target to PI3K/Akt signalling necessary for rh-insulin-induced GVBD in zebrafish.