Phosphorylation of Skp2 regulated by CDK2 and Cdc14B protects it from degradation by APCCdh1 in G1 phase

Authors

  • Geneviève Rodier,

    1. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
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    • These authors contributed equally to this work
    • Present address: Institut de Génétique Moléculaire, CNRS-UMII, 34293 Montpellier, France
  • Philippe Coulombe,

    1. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
    2. Department of Molecular Biology, Université de Montréal, Montreal, Quebec, Canada
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    • These authors contributed equally to this work
    • Present address: Institut de Génétique Humaine, CNRS, 34396 Montpellier, France
  • Pierre-Luc Tanguay,

    1. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
    2. Department of Molecular Biology, Université de Montréal, Montreal, Quebec, Canada
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  • Christel Boutonnet,

    1. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
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  • Sylvain Meloche

    Corresponding author
    1. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, Montreal, Quebec, Canada
    2. Department of Molecular Biology, Université de Montréal, Montreal, Quebec, Canada
    3. Department of Pharmacology, Université de Montréal, Montreal, Quebec, Canada
    • Corresponding author. Institut de Recherche en Immunologie et Cancérologie, Université de Montréal, 2950 chemin de Polytechnique, Marcelle-Coutu Pavilion, Montreal, Quebec, Canada H3C 3J7. Tel.: +1 514 343 6966; Fax: +1 514 343 5839; E-mail: sylvain.meloche@umontreal.ca

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Abstract

The p27Kip1 ubiquitin ligase receptor Skp2 is often overexpressed in human tumours and displays oncogenic properties. The activity of SCFSkp2 is regulated by the APCCdh1, which targets Skp2 for degradation. Here we show that Skp2 phosphorylation on Ser64/Ser72 positively regulates its function in vivo. Phosphorylation of Ser64, and to a lesser extent Ser72, stabilizes Skp2 by interfering with its association with Cdh1, without affecting intrinsic ligase activity. Cyclin-dependent kinase (CDK)2-mediated phosphorylation of Skp2 on Ser64 allows its expression in mid-G1 phase, even in the presence of active APCCdh1. Reciprocally, dephosphorylation of Skp2 by the mitotic phosphatase Cdc14B at the M → G1 transition promotes its degradation by APCCdh1. Importantly, lowering the levels of Cdc14B accelerates cell cycle progression from mitosis to S phase in an Skp2-dependent manner, demonstrating epistatic relationship of Cdc14B and Skp2 in the regulation of G1 length. Thus, our results reveal that reversible phosphorylation plays a key role in the timing of Skp2 expression in the cell cycle.

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