MAP kinase does not inactivate, but rather prevents the cyclin degradation pathway from being turned on in Xenopus egg extracts

Ariane Abrieu, Thierry Lorca, Jean-Claude Labbé, Nathalie Morin, Stephen Keyse, Marcel Dorée

    Research output: Contribution to journalArticle

    58 Citations (Scopus)

    Abstract

    Unfertilized frog eggs arrest at the second meiotic metaphase, due to cytostatic activity of the c-mos proto-oncogene (CSF). MAP kinase has been proposed to mediate CSF activity in suppressing cyclin degradation. Using an in vitro assay to generate CSF activity, and recombinant CL 100 phosphatase to inactivate MAP kinase, we confirm that the c-mos proto-oncogene blocks cyclin degradation through MAP kinase activation. We further show that for MAP kinase to suppress cyclin degradation, it must be activated before cyclin B-cdc2 kinase has effectively promoted cyclin degradation. Thus MAP kinase does not inactivate, but rather prevents the cyclin degradation pathway from being turned on. Using a constitutively active mutant of Ca2+/calmodulin dependent protein kinase II, which mediates the effects of Ca2+ at fertilization, we further show that the kinase can activate cyclin degradation in the presence of both MPF and the c-mos proto-oncogene without inactivating MAP kinase.
    Original languageEnglish
    Pages (from-to)239-246
    Number of pages8
    JournalJournal of Cell Science
    Volume109
    Issue number1
    Publication statusPublished - 1996

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