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ZFIN ID: ZDB-PUB-140624-3
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
Maitra, S., Das, D., Ghosh, P., Hajra, S., Roy, S.S., Bhattacharya, S.
Date: 2014
Source: Molecular and Cellular Endocrinology   393(1-2): 109-19 (Journal)
Registered Authors:
Keywords: Insulin, MAPK (ERK1/2), Okadaic acid, Oocyte, Zebrafish, cAMP/PKA
MeSH Terms:
  • Animals
  • Cells, Cultured
  • Cyclic AMP-Dependent Protein Kinases/metabolism*
  • Electrophoresis
  • Immunoblotting
  • Insulin/pharmacology
  • Meiosis*
  • Mitogen-Activated Protein Kinase 3/chemistry*
  • Mitogen-Activated Protein Kinase 3/metabolism
  • Oocytes/drug effects
  • Oocytes/enzymology*
  • Oocytes/metabolism
  • Zebrafish
PubMed: 24956082 Full text @ Mol. Cell. Endocrinol.
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 2 h 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.
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