title: High cAMP attenuation of insulin-stimulated meiotic G2-M1 transition in zebrafish oocytes: interaction between the cAMP-dependent protein kinase (PKA) and the MAPK3/1 pathways.
abstract: High intra-cellular cyclic nucleotide (cAMP) ensures prophase-I arrest and prevent steroid-induced meiotic G2-M1 transition in full-grown oocytes; however, relatively less information is available for cAMP regulation of growth factor-stimulated signalling events in the oocyte model. Here using zebrafish oocytes, we show that priming with dibutyryl cAMP (dbcAMP) or cAMP modulators, e.g. adenylate cyclase activator, forskolin or phosphodiesterase inhibitors (IBMX/cilostamide) block insulin action on germinal vesicle breakdown (GVBD) and histone H1 kinase activation. Though high cAMP priming attenuates insulin-induced MAPK3/1 (ERK1/2) phosphorylation (activation), following 2h of insulin stimulation it fails to block MAPK activation and GVBD. Further, insulin stimulation promotes down regulation of phospho-PKAc (inactivation) and PKA inhibition by H89/PKI-(6-22)-amide overcomes negative regulation by cAMP and induces GVBD and MAPK activation. Moreover, MEK1/2 inhibitor U0126 has no influence on H89-induced GVBD; however, it delays GVBD response in insulin-stimulated oocytes. MAPK activation by okadaic acid (OA) promotes GVBD; however, high dbcAMP abrogates OA action suggesting cross-talk between cAMP/PKA and MAPK-mediated signalling pathways may contribute significantly in maturing zebrafish oocyte.
authors: Department of Zoology, Visva-Bharati, Santiniketan 731235, India. Electronic address: smaitra3@gmail.com.
authors: Sudipta
authors: S
authors: Maitra
authors: Department of Zoology, Visva-Bharati, Santiniketan 731235, India.
authors: Debabrata
authors: D
authors: Das
authors: Department of Zoology, Visva-Bharati, Santiniketan 731235, India.
authors: Pritha
authors: P
authors: Ghosh
authors: Department of Zoology, Visva-Bharati, Santiniketan 731235, India.
authors: Sudip
authors: S
authors: Hajra
authors: CSIR-Indian Institute of Chemical Biology, 4, Raja S.C. Mullick Road, Kolkata 700032, India.
authors: Sib Sankar
authors: SS
authors: Roy
authors: Department of Zoology, Visva-Bharati, Santiniketan 731235, India.
authors: Samir
authors: S
authors: Bhattacharya
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D004586:Electrophoresis; D015151:Immunoblotting; D007328:Insulin / Q000494:pharmacology; D008540:Meiosis; D048052:Mitogen-Activated Protein Kinase 3 / Q000737:chemistry* / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D015027:Zebrafish
chemical_list: D007328:Insulin; D017868:Cyclic AMP-Dependent Protein Kinases; D048052:Mitogen-Activated Protein Kinase 3
keywords: Insulin; MAPK (ERK1/2); Okadaic acid; Oocyte; Zebrafish; cAMP/PKA