title: Proteomics reveals a switch in CDK1-associated proteins upon M-phase exit during the Xenopus laevis oocyte to embryo transition.
abstract: Cyclin-dependent kinase 1 (CDK1) is a major M-phase kinase which requires the binding to a regulatory protein, Cyclin B, to be active. CDK1/Cyclin B complex is called M-phase promoting factor (MPF) for its key role in controlling both meiotic and mitotic M-phase of the cell cycle. CDK1 inactivation is necessary for oocyte activation and initiation of embryo development. This complex process requires both Cyclin B polyubiquitination and proteosomal degradation via the ubiquitin-conjugation pathway, followed by the dephosphorylation of the monomeric CDK1 on Thr161. Previous proteomic analyses revealed a number of CDK1-associated proteins in human HeLa cells. It is, however, unknown whether specific partners are involved in CDK1 inactivation upon M-phase exit. To better understand CDK1 regulation during MII-arrest and oocyte activation, we immunoprecipitated (IPed) CDK1 together with its associated proteins from M-phase-arrested and M-phase-exiting Xenopus laevis oocytes. A mass spectrometry (MS) analysis revealed a number of new putative CDK1 partners. Most importantly, the composition of the CDK1-associated complex changed rapidly during M-phase exit. Additionally, an analysis of CDK1 complexes precipitated with beads covered with p9 protein, a fission yeast suc1 homologue well known for its high affinity for CDKs, was performed to identify the most abundant proteins associated with CDK1. The screen was auto-validated by identification of: (i) two forms of CDK1: Cdc2A and B, (ii) a set of Cyclins B with clearly diminishing number of peptides identified upon M-phase exit, (iii) a number of known CDK1 substrates (e.g. peroxiredoxine) and partners (e.g. HSPA8, a member of the HSP70 family) both in IP and in p9 precipitated pellets. In IP samples we also identified chaperones, which can modulate CDK1 three-dimensional structure, as well as calcineurin, a protein necessary for successful oocyte activation. These results shed a new light on CDK1 regulation via a dynamic change in the composition of the protein complex upon M-phase exit and the oocyte to embryo transition.
authors.affiliation: CNRS, UMR 6061, Institute of Genetics and Development of Rennes, Rennes, France.
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Marteil
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Gagné
authors.forename: Ewa
authors.initials: E
authors.lastname: Borsuk
authors.forename: Laurent
authors.initials: L
authors.lastname: Richard-Parpaillon
authors.forename: Guy G
authors.initials: GG
authors.lastname: Poirier
authors.forename: Jacek Z
authors.initials: JZ
authors.lastname: Kubiak
mesh_terms: D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D004625:Embryo, Nonmammalian; D005260:Female; D006801:Humans; D009865:Oocytes / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D014982:Xenopus laevis
chemical_list: D016203:CDC2 Protein Kinase