DNA polymerase zeta is required for proliferation of normal mammalian cells.
Unique among translesion synthesis (TLS) DNA polymerases, pol ζ is essential during embryogenesis. To determine whether pol ζ is necessary for proliferation of normal cells, primary mouse fibroblasts were established in which Rev3L could be conditionally inactivated by Cre recombinase. Cells were grown in 2% O(2) to prevent oxidative stress-induced senescence. Cells rapidly became senescent or apoptotic and ceased growth within 3-4 population doublings. Within one population doubling following Rev3L deletion, DNA double-strand breaks and chromatid aberrations were found in 30-50% of cells. These breaks were replication dependent, and found in G1 and G2 phase cells. Double-strand breaks were reduced when cells were treated with the reactive oxygen species scavenger N-acetyl-cysteine, but this did not rescue the cell proliferation defect, indicating that several classes of endogenously formed DNA lesions require Rev3L for tolerance or repair. T-antigen immortalization of cells allowed cell growth. In summary, even in the absence of external challenges to DNA, pol ζ is essential for preventing replication-dependent DNA breaks in every division of normal mammalian cells. Loss of pol ζ in slowly proliferating mouse cells in vivo may allow accumulation of chromosomal aberrations that could lead to tumorigenesis. Pol ζ is unique amongst TLS polymerases for its essential role in cell proliferation.
Department of Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center Science Park, and the Graduate School of Biomedical Sciences at Houston, Smithville Texas, P.O. Box 389, Smithville, TX 78957, USA.
Sabine S
SS
Lange
John P
JP
Wittschieben
Richard D
RD
Wood
D000818:Animals; D000957:Antigens, Viral, Tumor / Q000235:genetics; D017209:Apoptosis; D002455:Cell Division; D049109:Cell Proliferation; D002478:Cells, Cultured; D016922:Cellular Senescence; D002842:Chromatids; D053903:DNA Breaks, Double-Stranded; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D051379:Mice; D017382:Reactive Oxygen Species / Q000378:metabolism
D000957:Antigens, Viral, Tumor; D004268:DNA-Binding Proteins; D004259:DNA-Directed DNA Polymerase; D017382:Reactive Oxygen Species; C425929:DNA polymerase zeta; C486862:REV3L protein, mouse