Essential role of human CDT1 in DNA replication and chromatin licensing.
Formation of pre-replicative complexes at origins is an early cell cycle event essential for DNA duplication. A large body of evidence supports the notion that Cdc6 protein, through its interaction with the origin recognition complex, is required for pre-replicative complex assembly by loading minichromosome maintenance proteins onto DNA. In fission yeast and Xenopus, this reaction known as the licensing of chromatin for DNA replication also requires the newly identified Cdt1 protein. We studied the role of hCdt1 protein in the duplication of the human genome by antibody microinjection experiments and analyzed its expression during the cell cycle in human non-transformed cells. We show that hCdt1 is essential for DNA replication in intact human cells, that it executes its function in a window of the cell cycle overlapping with pre-replicative complex formation and that it is necessary for the loading of minichromosome maintenance proteins onto chromatin. Intriguingly, we observed that hCdt1 protein, in contrast to other licensing factors, is already present in serum-deprived G0 arrested cells and its levels increase only marginally upon re-entry in the cell cycle.
Rialland
Mickael
M
DRO-Oncology, Pharmacology Department, Pharmacia Corp., Via Pasteur 10, 20014 Nerviano, Italy.
Sola
Francesco
F
Santocanale
Corrado
C
D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D064148:Minichromosome Maintenance Complex Component 4; D011485:Protein Binding; D016196:S Phase; D029702:Schizosaccharomyces pombe Proteins; D014407:Tumor Cells, Cultured
C467199:CDT1 protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; D004268:DNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; D064148:Minichromosome Maintenance Complex Component 4; C078490:mcm4 protein, S pombe