title: Functional compartmentation of dCTP pools. Preferential utilization of salvaged deoxycytidine for DNA repair in human lymphoblasts.
abstract: The utilization of dCTP derived from de novo synthesis through ribonucleotide reductase in exponentially growing CCRF-CEM cells was compared with the metabolic fate of dCTP produced by the salvage pathway. Exogenous dCyd was not effectively incorporated into replicating DNA; instead, dCTP derived from ribonucleotide reductase (labeled by [5-3H]Cyd) was the main precursor for that purpose, apparently because of functional compartmentation of the dCTP pool in these cells. Studies of the metabolic route of incorporation of exogenous [5-3H]dCyd into DNA of growing CCRF-CEM cells demonstrated that it was mainly incorporated through the DNA repair pathway. Incorporation of [5-3H]dCyd into DNA of synchronized cell populations was maximal in G1 cells, whereas [3H]dThd incorporation occurred predominantly in S phase cells. When cellular DNA was density labeled by incubation with BrdUrd, repaired DNA, which was less dense than replicated DNA, was preferentially labeled by [5-3H]dCyd. In contrast, replicated DNA was labeled by both [3H]dThd and [5-3H]Cyd. The DNA-damaging agents methylmethanesulfonate, ultraviolet irradiation, and gamma-irradiation inhibited [3H]dThd incorporation, whereas they stimulated the accumulation of [5-3H]dCyd in DNA. Based on these results, we propose that the dCTP pool is functionally compartmentalized in growing CCRF-CEM cells. dCTP derived from the salvage pathway is utilized predominantly for DNA repair, whereas the de novo pathway supplies dCTP for DNA replication.
authors: Department of Clinical Investigation, University of Texas M. D. Anderson Cancer Center, Houston 77030.
authors: Y Z
authors: YZ
authors: Xu
authors: P
authors: P
authors: Huang
authors: W
authors: W
authors: Plunkett
mesh_terms: D001973:Bromodeoxyuridine; D002451:Cell Compartmentation; D002478:Cells, Cultured; D003562:Cytidine / Q000378:metabolism / Q000494:pharmacology; D004247:DNA / Q000187:drug effects; D004249:DNA Damage; D004260:DNA Repair; D003845:Deoxycytosine Nucleotides / Q000378:metabolism*; D006801:Humans; D008214:Lymphocytes; D013936:Thymidine / Q000378:metabolism
chemical_list: D003845:Deoxycytosine Nucleotides; C024107:2'-deoxycytidine 5'-triphosphate; D003562:Cytidine; D004247:DNA; D001973:Bromodeoxyuridine; D013936:Thymidine