title: Regulation of Claspin degradation by the ubiquitin-proteosome pathway during the cell cycle and in response to ATR-dependent checkpoint activation.
abstract: Claspin is involved in ATR-dependent activation of Chk1 during DNA replication and in response to DNA damage. We show that degradation of Claspin by the ubiquitin-proteosome pathway is regulated during the cell cycle. Claspin is stabilized in S-phase but is abruptly degraded in mitosis and is absent from early G(1) cells in which the phosphorylation of Chk1 by ATR is abrogated. In response to hydroxyurea, UV or aphidicolin, Claspin is phosphorylated in the Chk1-binding domain and its protein levels are increased in an ATR-dependent manner. Thus, the Chk1 pathway is regulated through both phosphorylation of Claspin and its controlled degradation.
authors.affiliation: Biomedical Research Centre, Level 5, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK.
authors.forename: Lara N
authors.initials: LN
authors.lastname: Bennett
authors.forename: Paul R
authors.initials: PR
authors.lastname: Clarke
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000970:Antineoplastic Agents / Q000494:pharmacology; D016590:Aphidicolin / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D000071877:Checkpoint Kinase 1; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016193:G1 Phase / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D008938:Mitosis / Q000187:drug effects / Q000528:radiation effects; D010766:Phosphorylation / Q000187:drug effects / Q000528:radiation effects; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D011499:Protein Processing, Post-Translational / Q000187:drug effects / Q000528:radiation effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D016196:S Phase / Q000187:drug effects / Q000528:radiation effects; D015398:Signal Transduction / Q000187:drug effects / Q000528:radiation effects; D025801:Ubiquitin / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000970:Antineoplastic Agents; C488158:CLSPN protein, human; D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D025801:Ubiquitin; D016590:Aphidicolin; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex; D006918:Hydroxyurea