title: Dynamics of DNA replication in mammalian somatic cells: nucleotide pool modulates origin choice and interorigin spacing.
abstract: Selection of active origins and regulation of interorigin spacing are poorly understood in mammalian cells. Using tricolor analysis of combed DNA molecules, we studied an amplified locus containing the known origin, oriGNAI3. We visualized replication firing events at this and other discrete regions and established a strict correlation between AT richness and initiation sites. We found that oriGNAI3 is the prominent origin of the domain, the firing of which correlates with silencing of neighboring sites and establishes large interorigin distances. We demonstrate that cells reversibly respond to a reduction in nucleotide availability by slowing the rate of replication fork progression; in addition, the efficiency of initiation at oriGNAI3 is lowered while other normally dormant origins in the region are activated, which results in an overall increase in the density of initiation events. Thus, nucleotide pools are involved in the specification of active origins, which in turn defines their density along chromosomes.
authors.affiliation: Institut Curie, FRE 2584, 26 rue d'Ulm, 75248 Paris, France.
authors.forename: Mauro
authors.initials: M
authors.lastname: Anglana
authors.forename: Françoise
authors.initials: F
authors.lastname: Apiou
authors.forename: Aaron
authors.initials: A
authors.lastname: Bensimon
authors.forename: Michelle
authors.initials: M
authors.lastname: Debatisse
mesh_terms: D000659:AMP Deaminase / Q000235:genetics; D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002460:Cell Line; D002874:Chromosome Mapping / Q000379:methods; D006224:Cricetinae; D004247:DNA / Q000235:genetics* / Q000378:metabolism; D004261:DNA Replication / Q000502:physiology*; D005057:Eukaryotic Cells / Q000502:physiology*; D017403:In Situ Hybridization; D009711:Nucleotides / Q000378:metabolism*; D018741:Replication Origin
chemical_list: D009711:Nucleotides; D004247:DNA; D000659:AMP Deaminase