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  • The EMBO Journal (2002) 21, 4026 - 4036
  • doi:10.1093/emboj/cdf400

Mos is not required for the initiation of meiotic maturation in Xenopus oocytes

Aude Dupré1, Catherine Jessus1, René Ozon1 and Olivier Haccard1

  1. Laboratoire de Biologie du Développement, UMR–CNRS 7622, Université Pierre et Marie Curie, boîte 24, 4 place Jussieu, 75252 Paris cedex 05, France

Correspondence to:

Olivier Haccard, E-mail: olh@ccr.jussieu.fr

Received 1 March 2002; Accepted 7 June 2002; Revised 6 June 2002

In Xenopus oocytes, the c-mos proto-oncogene product has been proposed to act downstream of progesterone to control the entry into meiosis I, the transition from meiosis I to meiosis II, which is characterized by the absence of S phase, and the metaphase II arrest seen prior to fertilization. Here, we report that inhibition of Mos synthesis by morpholino antisense oligonucleotides does not prevent the progesterone-induced initiation of Xenopus oocyte meiotic maturation, as previously thought. Mos-depleted oocytes complete meiosis I but fail to arrest at metaphase II, entering a series of embryonic-like cell cycles accompanied by oscillations of Cdc2 activity and DNA replication. We propose that the unique and conserved role of Mos is to prevent mitotic cell cycles of the female gamete until the fertilization in Xenopus, starfish and mouse oocytes.

  • Keywords:

    • cdc2,
    • mos,
    • oocyte,
    • proto-oncogene,
    • Xenopus