Nucleic Acids Research, 2001, Vol. 29, No. 8 1653-1660
© 2001 Oxford University Press
Genetic evidence for the involvement of DNA ligase IV in the DNA-PK-dependent pathway of non-homologous end joining in mammalian cells
Department of Radiation Oncology, Division of Experimental Radiation Oncology, Kimmel Cancer Center, Jefferson Medical College, Philadelphia, PA 19107, USA
Cells of vertebrates remove DNA double-strand breaks (DSBs) from their genome predominantly utilizing a fast, DNA-PKcs-dependent form of non-homologous end joining (D-NHEJ). Mutants with inactive DNA-PKcs remove the majority of DNA DSBs utilizing a slow, DNA-PKcs-independent pathway that does not utilize genes of the RAD52 epistasis group, is error-prone and can therefore be classified as a form of NHEJ (termed basic or B-NHEJ). We studied the role of DNA ligase IV in these pathways of NHEJ. Although biochemical studies show physical and functional interactions between the DNA-PKcs/Ku and the DNA ligase IV/Xrcc4 complexes suggesting operation within the same pathway, genetic evidence to support this notion is lacking in mammalian cells. Primary human fibroblasts (180BR) with an inactivating mutation in DNA ligase IV, rejoined DNA DSBs predominantly with slow kinetics similar to those observed in cells deficient in DNA-PKcs, or in wild-type cells treated with wortmannin to inactivate DNA-PK. Treatment of 180BR cells with wortmannin had only a small effect on DNA DSB rejoining and no effect on cell radiosensitivity to killing although it sensitized control cells to 180BR levels. This is consistent with DNA ligase IV functioning as a component of the D-NHEJ, and demonstrates the unperturbed operation of the DNA-PKcs-independent pathway (B-NHEJ) at significantly reduced levels of DNA ligase IV. In vitro, extracts of 180BR cells supported end joining of restriction endonuclease-digested plasmid to the same degree as extracts of control cells when tested at 10 mM Mg2+. At 0.5 mM Mg2+, where only DNA ligase IV is expected to retain activity, low levels of end joining (
10% of 10 mM) were seen in the control but there was no detectable activity in 180BR cells. Antibodies raised against DNA ligase IV did not measurably inhibit end joining at 10 mM Mg2+ in either cell line. Thus, in contrast to the situation in vivo, end joining in vitro is dominated by pathways with properties similar to B-NHEJ that do not display a strong dependence on DNA ligase IV, with D-NHEJ retaining only a limited contribution. The implications of these observations to studies of NHEJ in vivo and in vitro are discussed.
* To whom correspondence should be addressed. Tel: +1 215 955 6473; Fax: +1 215 955 2052; Email: george.iliakis{at}mail.tju.edu
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
L. Liang, L. Deng, S. C. Nguyen, X. Zhao, C. D. Maulion, C. Shao, and J. A. Tischfield Human DNA ligases I and III, but not ligase IV, are required for microhomology-mediated end joining of DNA double-strand breaks Nucleic Acids Res., June 1, 2008; 36(10): 3297 - 3310. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. Rosidi, M. Wang, W. Wu, A. Sharma, H. Wang, and G. Iliakis Histone H1 functions as a stimulatory factor in backup pathways of NHEJ Nucleic Acids Res., March 1, 2008; 36(5): 1610 - 1623. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. F. Povirk, R.-Z. Zhou, D. A. Ramsden, S. P. Lees-Miller, and K. Valerie Phosphorylation in the serine/threonine 2609-2647 cluster promotes but is not essential for DNA-dependent protein kinase-mediated nonhomologous end joining in human whole-cell extracts Nucleic Acids Res., June 9, 2007; 35(12): 3869 - 3878. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Kuhfittig-Kulle, E. Feldmann, A. Odersky, A. Kuliczkowska, W. Goedecke, A. Eggert, and P. Pfeiffer The mutagenic potential of non-homologous end joining in the absence of the NHEJ core factors Ku70/80, DNA-PKcs and XRCC4-LigIV Mutagenesis, May 1, 2007; 22(3): 217 - 233. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Wang, W. Wu, W. Wu, B. Rosidi, L. Zhang, H. Wang, and G. Iliakis PARP-1 and Ku compete for repair of DNA double strand breaks by distinct NHEJ pathways Nucleic Acids Res., December 4, 2006; 34(21): 6170 - 6182. [Abstract] [Full Text] [PDF] |
||||
![]() |
B. J. Andrews, J. A. Lehman, and J. J. Turchi Kinetic Analysis of the Ku-DNA Binding Activity Reveals a Redox-dependent Alteration in Protein Structure That Stimulates Dissociation of the Ku-DNA Complex J. Biol. Chem., May 12, 2006; 281(19): 13596 - 13603. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. Enders, P. Fisch, K. Schwarz, U. Duffner, U. Pannicke, E. Nikolopoulos, A. Peters, M. Orlowska-Volk, D. Schindler, W. Friedrich, et al. A Severe Form of Human Combined Immunodeficiency Due to Mutations in DNA Ligase IV. J. Immunol., April 15, 2006; 176(8): 5060 - 5068. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Liang, L. Deng, Y. Chen, G. C. Li, C. Shao, and J. A. Tischfield Modulation of DNA End Joining by Nuclear Proteins J. Biol. Chem., September 9, 2005; 280(36): 31442 - 31449. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Wang, B. Rosidi, R. Perrault, M. Wang, L. Zhang, F. Windhofer, and G. Iliakis DNA Ligase III as a Candidate Component of Backup Pathways of Nonhomologous End Joining Cancer Res., May 15, 2005; 65(10): 4020 - 4030. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. J. Romeijn, M. M. Gorski, M. A. van Schie, J. N. Noordermeer, L. H. Mullenders, W. Ferro, and A. Pastink Lig4 and Rad54 Are Required for Repair of DNA Double-Strand Breaks Induced by P-Element Excision in Drosophila Genetics, February 1, 2005; 169(2): 795 - 806. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Kuhne, E. Riballo, N. Rief, K. Rothkamm, P. A. Jeggo, and M. Lobrich A Double-Strand Break Repair Defect in ATM-Deficient Cells Contributes to Radiosensitivity Cancer Res., January 15, 2004; 64(2): 500 - 508. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. Wang, A. R. Perrault, Y. Takeda, W. Qin, H. Wang, and G. Iliakis Biochemical evidence for Ku-independent backup pathways of NHEJ Nucleic Acids Res., September 15, 2003; 31(18): 5377 - 5388. [Abstract] [Full Text] [PDF] |
||||
![]() |
F. Delacote, M. Han, T. D. Stamato, M. Jasin, and B. S. Lopez An xrcc4 defect or Wortmannin stimulates homologous recombination specifically induced by double-strand breaks in mammalian cells Nucleic Acids Res., August 1, 2002; 30(15): 3454 - 3463. [Abstract] [Full Text] [PDF] |
||||
![]() |
Q. Zhong, T. G. Boyer, P.-L. Chen, and W.-H. Lee Deficient Nonhomologous End-Joining Activity in Cell-free Extracts from Brca1-null Fibroblasts Cancer Res., July 15, 2002; 62(14): 3966 - 3970. [Abstract] [Full Text] [PDF] |
||||
![]() |
N. Rief and M. Lobrich Efficient Rejoining of Radiation-induced DNA Double-strand Breaks in Centromeric DNA of Human Cells J. Biol. Chem., May 31, 2002; 277(23): 20572 - 20582. [Abstract] [Full Text] [PDF] |
||||
![]() |
C. D. Braastad, M. Leguia, and E. A. Hendrickson Ku86 autoantigen related protein-1 transcription initiates from a CpG island and is induced by p53 through a nearby p53 response element Nucleic Acids Res., April 15, 2002; 30(8): 1713 - 1724. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. Rodgers, S. J. Jordan, and J. D. Capra Transient Association of Ku with Nuclear Substrates Characterized Using Fluorescence Photobleaching J. Immunol., March 1, 2002; 168(5): 2348 - 2355. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. Li, C. Nelsen, and E. A. Hendrickson Ku86 is essential in human somatic cells PNAS, January 22, 2002; 99(2): 832 - 837. [Abstract] [Full Text] [PDF] |
||||






