Activated alpha subunit of Go protein induces oocyte maturation.

AUTOR(ES)

Kroll, S D

RESUMO

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.

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