title: Activated alpha subunit of Go protein induces oocyte maturation.
abstract: The capability of various activated guanine nucleotide binding regulatory protein (G protein) alpha subunits to induce meiotic maturation was studied. Activated Go protein alpha subunit (alpha o*) but not the three inhibitory G protein alpha subunits triggered meiotic maturation in Xenopus oocytes. The effect was concentration dependent with a half-maximal effect in the 100-200 pM range. Injection of alpha o* stimulated protein kinase C activity. Coinjection of the peptide containing residues 19-36 of protein kinase C [PKC-(19-36)], a specific protein kinase C inhibitor, blocked the alpha o*- but not progesterone-induced maturation. Cycloheximide and the injection of antisense oligonucleotides specific to the c-mos transcript blocked alpha o-induced maturation. Immunoprecipitation with a mos protein-specific monoclonal antibody showed that alpha o-injected oocytes had phosphorylated mos protein. When PKC-(19-36) was coinjected with alpha o*, phosphorylated mos protein was not observed. These observations indicate that alpha o*, through protein kinase C and the translation of c-mos, can trigger meiotic division of Xenopus oocytes. Our results raise the possibility that persistently activated G proteins through cellular protooncogenes may regulate cell-cycle resumption.
authors.affiliation: Department of Pharmacology, Mount Sinai School of Medicine, City University of New York, NY 10029.
authors.forename: S D
authors.initials: SD
authors.lastname: Kroll
authors.forename: G
authors.initials: G
authors.lastname: Omri
authors.forename: E M
authors.initials: EM
authors.lastname: Landau
authors.forename: R
authors.initials: R
authors.lastname: Iyengar
mesh_terms: D000818:Animals; D002875:Chromosomes; D005260:Female; D019204:GTP-Binding Proteins / Q000378:metabolism*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D011233:Precipitin Tests; D011374:Progesterone / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D017231:Proto-Oncogene Proteins c-mos; D014981:Xenopus
chemical_list: D011518:Proto-Oncogene Proteins; D011374:Progesterone; D011505:Protein-Tyrosine Kinases; D017231:Proto-Oncogene Proteins c-mos; D011493:Protein Kinase C; D019204:GTP-Binding Proteins