Journal of Biological Chemistry · 2008 · 241 citations · 33 references
Life SciencesCell BiologyMolecular BiologyChromatin BiologyChromatin StructureDna ReplicationCell-cycle RegulationChromatinDna Damage SignalingProtein DegradationReplication LicensingS PhaseMutational Analysis Of BindingP21 PathwayP21 RegulationProteolysis In Cell-cycle ControlSubstrate Recognition In Ubiquitin PathwaysUbiquitin-mediated ProteolysisUbiquitin-proteasome ProteolysisUbiquitination Of Proliferating Cell Nuclear Antigen
Previous reports showed that chromatin-associated PCNA couples DNA replication with Cul4-DDB1Cdt2-dependent proteolysis of the licensing factor Cdt1. The CDK inhibitor p21, another PCNA-binding protein, is also degraded both in S phase and after UV irradiation. Here we show that p21 is degraded by the same ubiquitin-proteasome pathway as Cdt1 in HeLa cells. When PCNA or components of Cul4-DDB1Cdt2 were silenced or when the PCNA binding site on p21 was mutated, degradation of p21 was prevented both in S phase and after UV irradiation. p21 was co-immunoprecipitated with Cul4A and DDB1 proteins when expressed in cells. The purified Cul4A-DDB1Cdt2 complex ubiquitinated p21 in vitro. Consistently, p21 protein levels are low during S phase and increase around G2 phase. Mutational analysis suggested that in addition to the PCNA binding domain, its flanking regions are also important for recognition by Cul4-DDB1Cdt2. Our findings provide a new aspect of proteolytic control of p21 during the cell cycle. Previous reports showed that chromatin-associated PCNA couples DNA replication with Cul4-DDB1Cdt2-dependent proteolysis of the licensing factor Cdt1. The CDK inhibitor p21, another PCNA-binding protein, is also degraded both in S phase and after UV irradiation. Here we show that p21 is degraded by the same ubiquitin-proteasome pathway as Cdt1 in HeLa cells. When PCNA or components of Cul4-DDB1Cdt2 were silenced or when the PCNA binding site on p21 was mutated, degradation of p21 was prevented both in S phase and after UV irradiation. p21 was co-immunoprecipitated with Cul4A and DDB1 proteins when expressed in cells. The purified Cul4A-DDB1Cdt2 complex ubiquitinated p21 in vitro. Consistently, p21 protein levels are low during S phase and increase around G2 phase. Mutational analysis suggested that in addition to the PCNA binding domain, its flanking regions are also important for recognition by Cul4-DDB1Cdt2. Our findings provide a new aspect of proteolytic control of p21 during the cell cycle.
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SKP2 is required for ubiquitin-mediated degradation of the CDK inhibitor p27
Andrea C. Carrano, Esther Eytan, Avram Hershko et al. · Nature Cell Biology · 1999 · 1.5K citations
A p53-Dependent Checkpoint Pathway Prevents Rereplication
Cyrus Vaziri, Sandeep Saxena, Yesu Jeon et al. · Molecular Cell · 2003 · 390 citations · Full text