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W1990997564 abstract "Fanconi anemia (FA) is a heterogeneous autosomal recessive disease characterized by congenital abnormalities, pancytopenia, and an increased incidence of cancer. Cells cultured from FA patients display elevated spontaneous chromosomal breaks and deletions and are hypersensitive to bifunctional cross-linking agents. Thus, it has been hypothesized that FA is a DNA repair disorder. We analyzed plasmid end-joining in intact diploid fibroblast cells derived from FA patients. FA fibroblasts from complementation groups A, C, D2, and G rejoined linearized plasmids with a significantly decreased efficiency compared with non-FA fibroblasts. Retrovirus-mediated expression of the respective FA cDNAs in FA cells restored their end-joining efficiency to wild type levels. Human FA fibroblasts and fibroblasts from FA rodent models were also significantly more sensitive to restriction enzyme-induced chromosomal DNA double strand breaks than were their retrovirally corrected counterparts. Taken together, these data show that FA fibroblasts have a deficiency in both extra-chromosomal and chromosomal DNA double strand break repair, a defect that could provide an attractive explanation for some of the pathologies associated with FA. Fanconi anemia (FA) is a heterogeneous autosomal recessive disease characterized by congenital abnormalities, pancytopenia, and an increased incidence of cancer. Cells cultured from FA patients display elevated spontaneous chromosomal breaks and deletions and are hypersensitive to bifunctional cross-linking agents. Thus, it has been hypothesized that FA is a DNA repair disorder. We analyzed plasmid end-joining in intact diploid fibroblast cells derived from FA patients. FA fibroblasts from complementation groups A, C, D2, and G rejoined linearized plasmids with a significantly decreased efficiency compared with non-FA fibroblasts. Retrovirus-mediated expression of the respective FA cDNAs in FA cells restored their end-joining efficiency to wild type levels. Human FA fibroblasts and fibroblasts from FA rodent models were also significantly more sensitive to restriction enzyme-induced chromosomal DNA double strand breaks than were their retrovirally corrected counterparts. Taken together, these data show that FA fibroblasts have a deficiency in both extra-chromosomal and chromosomal DNA double strand break repair, a defect that could provide an attractive explanation for some of the pathologies associated with FA. Fanconi anemia (FA) 1The abbreviations used for: FA, Fanconi anemia; SRB, sulforhodamine B. 1The abbreviations used for: FA, Fanconi anemia; SRB, sulforhodamine B. is a fatal inherited autosomal recessive disease characterized by progressive bone marrow failure and a significant predisposition toward malignancies, particularly acute myelogenous leukemia (1Auerbach A.D. Allen R.G. Cancer Genet. Cytogenet. 1991; 51: 1-12Abstract Full Text PDF PubMed Scopus (248) Google Scholar, 2D'Andrea A.D. Grompe M. Blood. 1997; 90: 1725-1736Crossref PubMed Google Scholar). Somatic cell hybridization studies have shown that abnormalities in multiple genes result in FA (3Joenje H. Oostra A.B. Wijker M. di Summa F.M. van Berkel C.G. Rooimans M.A. Ebell W. van Weel M. Pronk J.C. Buchwald M. Arwert F. Am. J. Hum. Genet. 1997; 61: 940-944Abstract Full Text PDF PubMed Scopus (252) Google Scholar, 4Joenje H. Levitus M. Waisfisz Q. D'Andrea A.D. Garcia-Higuera I. Pearson T. van Berkel C.G. Rooimans M.A. Morgan N. Mathew C.G. Arwert F. Am. J. Hum. Genet. 2000; 67: 759-762Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar, 5Timmers C. Taniguchi T. Hejna J. Reifsteck C. Lucas L. Bruun D. Thayer M. Cox B. Olson S. D'Andrea A.D. Moses R. Grompe M. Mol. Cell. 2001; 7: 241-248Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar). To date, at least eight distinct complementation groups have been identified (A, B, C, D1, D2, E, F, and G), and all of the known FA genes have been cloned (6Strathdee C.A. Gavish H. Shannon W.R. Buchwald M. Nature. 1992; 356: 763-767Crossref PubMed Scopus (534) Google Scholar, 7The Fanconi anaemia/Breast Cancer Consortium. Nat. Genet. 1996; 14: 324-328Crossref PubMed Scopus (261) Google Scholar, 8Lo Ten Foe J.R. Rooimans M.A. Bosnoyan-Collins L. Alon N. Wijker M. Parker L. Lightfoot J. Carreau M. Callen D.F. Savoia A. Cheng N.C. van Berkel C.G. Strunk M.H. Gille J.J. Pals G. Kruyt F.A. Pronk J.C. Arwert F. Buchwald M. Joenje H. Nat. Genet. 1996; 14: 320-323Crossref PubMed Scopus (300) Google Scholar, 9de Winter J.P. Waisfisz Q. Rooimans M.A. van Berkel C.G.M. Bosnoyan-Collins L. Alon N. Carreau M. Bender O. Demuth I. Schindler D. Pronk J.C. Arwert F. Hoehn H. Digweed M. Buchwald M. Joenje H. Nat. Genet. 1998; 20: 281-283Crossref PubMed Scopus (282) Google Scholar, 10de Winter J.P. Leveille F. van Berkel C.G.M. Rooimans M.A. van der Weel L. Steltenpool J. Demuth I. Morgan N.V. Alon N. Bosnoyan-Collins L. Lightfoot J. Leegwater P.A. Waisfisz Q. Komatsu K. Arwert F. Pronk J.C. Mathew C.G. Digweed M. Buchwald M. Joenje J. Am. J. Hum. Genet. 2000; 67: 1306-1308Abstract Full Text Full Text PDF PubMed Scopus (190) Google Scholar, 11de Winter J.P. Rooimans M.A. van der Weel L. van Berkel C.G.M. Alon N. Bosnoyan-Collins L. de Groot J. Zhi Y. Waisfisz Q. Pronk J.C. Arwert F. Mathew C.G. Scheper R.J. Nat. Genet. 2000; 24: 15-16Crossref PubMed Scopus (234) Google Scholar, 12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar). With the exception of FANCB, and FANCD1, none of the FA genes contains sequence motifs of known function (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar), and onlyFANCD2 has been found to have a homolog in lower eukaryotic organisms (5Timmers C. Taniguchi T. Hejna J. Reifsteck C. Lucas L. Bruun D. Thayer M. Cox B. Olson S. D'Andrea A.D. Moses R. Grompe M. Mol. Cell. 2001; 7: 241-248Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar). Some of the FA genes encode proteins that interact to form a complex in the nucleus. This complex is disrupted in cell lines from complementation groups A, C, E, F, and G (13de Winter J.P. van der Weel L. de Groot J. Stone S. Waisfisz Q. Arwert F. Scheper R.J. Kruyt F.A.E. Hoatlin M.E. Joenje H. Hum. Mol. Genet. 2000; 9: 2665-2674Crossref PubMed Scopus (172) Google Scholar, 14Medhurst A.L. Huber P.A. Waisfisz Q. de Winter J.P. Mathew C.G. Hum. Mol. Genet. 2001; 10: 423-429Crossref PubMed Scopus (140) Google Scholar). Yet despite these findings, the exact biological functions of the FA proteins have not yet been determined and the molecular mechanism(s) responsible for FA have remained obscure (15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar).Interestingly, although the molecular defect responsible for FA is unclear, it has been well documented that cells from FA patients display elevated levels of spontaneous chromosomal breaks and deletions and have an increased sensitivity to the cytotoxic and clastogenic effects of DNA cross-linking agents (16Ishida R. Buchwald M. Cancer Res. 1982; 42: 4000-4006PubMed Google Scholar, 17Papadopoulo D. Guillouf C. Mohrenweiser H. Moustacchi E. Proc. Natl. Acad. Sci. U. S. A. 1990; 87: 8383-8387Crossref PubMed Scopus (109) Google Scholar, 18Auerbach A.D. Exp. Hematol. 1993; 21: 731-733PubMed Google Scholar, 19Carreau M. Alon N. Bosnoyan-Collins L. Joenje H. Buchwald M. Mutat. Res. 1999; 435: 103-109Crossref PubMed Scopus (59) Google Scholar). Patient-derived FA lymphoblasts have been shown to have significantly decreased plasmid-rejoining fidelity compared with normal lymphoblasts (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar). Additionally, nuclear extracts from patient-derived FA fibroblasts have substantially decreased plasmid-rejoining activity compared with extracts from normal fibroblasts (22Lundberg R. Mavinakere M. Campbell C. J. Biol. Chem. 2001; 276: 9543-9549Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar). These cellular features along with the high susceptibility of FA patients to cancers have lead to the hypothesis that this disorder results from defective DNA repair. However, the absence of recognizable DNA binding sequence motifs in FA genes and the lack of evidence showing direct interaction of FA gene products with DNA cast doubt on the idea that FA proteins directly participate in DNA repair. Recent results demonstrating a connection between the BRCA1 and BRCA2 tumor suppressor and FA proteins suggest that FA proteins may play an essential role in regulating the cellular response to DNA damage (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar, 15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar, 23Patel K.J. Yu V.P. Lee H. Coircoran A. Thistlethwaite F.C. Evans M.J. Colledge W.H. Friedman L.S. Ponder B.A. Venkitaraman A.R. Mol. Cell. 1998; 1: 347-357Abstract Full Text Full Text PDF PubMed Scopus (520) Google Scholar, 24Garcia-Higuera I. Taniguchi T. Ganesan S. Meyn M.S. Timmers C. Hejna J. Grompe M. D'Andrea A.D. Mol. Cell. 2001; 7: 249-262Abstract Full Text Full Text PDF PubMed Scopus (1019) Google Scholar, 25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar).We examined both extra-chromosomal and chromosomal DNA repair in intact FA fibroblasts and retrovirally corrected FA fibroblasts from multiple complementation groups and animal models. We found that fibroblasts derived from FA patients of complementation groups A, C, D2, and G were significantly deficient in the repair of both plasmid and chromosome DNA double strand breaks and that this deficiency was corrected by the expression of the respective FA cDNAs in these cells. Furthermore, a similar defect in DNA double strand break repair was seen in cells derived from two rodent models of FA and in wild type cells expressing a dominant negative FANCC allele.DISCUSSIONThe data presented herein support the conclusion that FA fibroblasts have a dramatically reduced ability to rejoin double strand breaks in both introduced plasmids as well as within their chromosomes. These defects were observed in diploid fibroblasts from patients whose cells belong to a number of different FA complementation groups. In all cases tested, the re-introduction of the deficient FA gene into these cells eliminated the aberrant phenotype. An inability to repair restriction enzyme-induced chromosomal double strand breaks was also observed in two different rodent models of FA as well as in a human cell culture model of FA induced by overexpression of a dominant negative allele of the FANCC gene. Taken together, these findings provide robust support for the conclusion that FA fibroblasts have a defect in cellular DNA double strand break repair.The nature of the DNA double strand break repair defect in FA fibroblasts, however, remains obscure. It is known that mammalian cells use both recombinational and non-homologous end-joining pathways to repair DNA double strand breaks. Thus, in principle, either mechanism or conceivably both could be affected in FA fibroblasts. It is not likely that the linearized plasmid substrates utilized in our end-joining assays are repaired via a recombinational mechanism. Thus, we can conclude that FA fibroblasts have a defect in a non-recombinational DNA double strand break repair pathway. The findings that V(D)J recombination and Ku-dependent non-homologous end-joining are not affected in FA cells (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 22Lundberg R. Mavinakere M. Campbell C. J. Biol. Chem. 2001; 276: 9543-9549Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar, 37Smith J. Andrau J.C. Kallenbach S. Laquerbe A. Doyen N. Papadopoulo D. J. Mol. Biol. 1998; 281: 815-825Crossref PubMed Scopus (38) Google Scholar) indicate that this observed defect does not involve these pathways. Instead, it appears that the deficiency resides in another currently uncharacterized non-recombinational repair pathway.It is tempting to speculate that the hypersensitivity of FA fibroblasts to restriction enzyme-induced chromosomal double strand breaks is a consequence of deficient non-recombinational repair of these lesions. However, a number of findings suggest that this hypersensitivity could reflect a deficiency in chromosomal homologous recombinational repair. First, the BRCA1 protein, which is required for efficient recombinational repair of chromosome double strand breaks, co-localizes to nuclear foci with the FANCD2 protein in cells following exposure to ionizing radiation (24Garcia-Higuera I. Taniguchi T. Ganesan S. Meyn M.S. Timmers C. Hejna J. Grompe M. D'Andrea A.D. Mol. Cell. 2001; 7: 249-262Abstract Full Text Full Text PDF PubMed Scopus (1019) Google Scholar). FANCD2 has also been shown to be phosphorylated in an ATM-dependent manner following induced DNA damage (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). Second, the FANCB andFANCD1 genes are apparently identical to BRCA2, a gene also required for efficient recombinational repair of chromosome double strand breaks (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar, 15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar, 38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar). Third, both the BRCA1 and BRCA2 proteins interact with the mammalian RecA homolog Rad51 (39Venkitaraman A.R. J. Cell Sci. 2001; 114: 3591-3598PubMed Google Scholar), and cells deficient in BRCA1 and/or BRCA2 have a significant defect in homologous recombination, display chromosomal instability, and are hypersensitive to DNA cross-linking agents as are FA cells (38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar, 40Jachymczyk W.J. von Borstel R.C. Mowat M.R. Hastings P.J. Mol. Gen. Genet. 1981; 182: 196-205Crossref PubMed Scopus (158) Google Scholar, 41Caldecott K. Jeggo P.A. Mutat. Res. 1991; 255: 111-121Crossref PubMed Scopus (132) Google Scholar, 42Liu N. Lamerdin J.E. Tebbs R.S. Schild D. Tucker J.D. Shen M.R. Brookman K.W. Siciliano M.J. Walter C.A. Fan W. Narayana L.S. Zhou Z.Q. Adamson A.W. Sorensen K.J. Chen D.J. Jones N.J. Thompson L.H. Mol. Cell. 1998; 1: 783-793Abstract Full Text Full Text PDF PubMed Scopus (470) Google Scholar, 43Scully R. Chen J. Ochs R.L. Keegan K. Hoekstra M. Feunteun J. Livingston D.M. Cell. 1997; 90: 425-435Abstract Full Text Full Text PDF PubMed Scopus (806) Google Scholar, 44Snouwaert J.N. Gowen L.C. Latour A.M. Mohn A.R. Xiao A. DiBiase L. Koller B.H. Oncogene. 1999; 18: 7900-7907Crossref PubMed Scopus (165) Google Scholar, 45Moynahan M.E. Cui T.Y. Jasin M. Cancer Res. 2001; 61: 4842-4850PubMed Google Scholar). Thus, it is conceivable that FA cells have a defect in recombinational repair of chromosomal DNA double strand breaks. It remains to be determined whether the elevated sensitivity of FA cells to restriction enzyme-induced cell death is a consequence of defective non-homologous end-joining, defective recombinational repair, or both. It may be possible to gain insight into this question by studying the repair of double strand breaks induced into engineered chromosomal loci by rare-cutting endonucleases such as the yeast I SceI enzyme.An alternative explanation for the cytotoxicity observed in FA fibroblasts following introduction of restriction enzymes is that cell death may be due to improper checkpoint regulation following chromosomal damage. A recent report by Taniguchi et al. (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar) shows that FANCD2 fibroblasts have radio-resistant DNA synthesis following induced DNA damage. Similarly, BRCA2/FANCD1-deficient Chinese hamster ovary cells and BRCA1-deficient cells also display radio-resistant DNA synthesis after exposure to ionizing radiation (46Kraakman-van der Zwet M. Overkamp W.J.I. van Lange R.E.E. Essers J. van Duijn-Goedhart A. Wiggers I. Swaminathan S. van Buul P.P.W. Errami A. Tan R.T.L. Jaspers N.G.J. Sharan S.K. Kanaar R. Zdzienicka M.Z. Mol. Cell. Biol. 2002; 22: 669-679Crossref PubMed Scopus (228) Google Scholar,47Xu B. Kim S. Kastan M.B. Mol. Cell. Biol. 2001; 21: 3445-3450Crossref PubMed Scopus (470) Google Scholar). Thus, given the association among FA proteins and BRCA1 and BRCA2 previously outlined, these data indicate that FA cells may have an S phase checkpoint defect. Failed repair of DNA double strand breaks and an inability to regulate an essential checkpoint may result in these FA cells progressing through the cell cycle with unrepaired chromosomal lesions that would ultimately lead to cell death.Regardless of the nature of the defect, the deficiency in DNA double strand break repair observed in FA fibroblasts may provide an attractive explanation for some of the pathologies associated with FA. Although this conclusion is derived from studies performed on fibroblast cells and may not be applicable to all cell types, evidence from lymphoblasts derived from FA patients also indicates a deficiency in DNA double strand break repair (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 48Runger T.M. Sobotta P. Dekant B. Moller K. Bauer C. Kraemer K.H. Toxicol Lett. 1993; 67: 309-324Crossref PubMed Scopus (13) Google Scholar). Additionally, an examination of both fibroblasts and lymphoblasts derived from FA patients has revealed no distinct differences in sensitivities to DNA-damaging agents or chromosomal instability, the two main cellular features of FA (16Ishida R. Buchwald M. Cancer Res. 1982; 42: 4000-4006PubMed Google Scholar, 19Carreau M. Alon N. Bosnoyan-Collins L. Joenje H. Buchwald M. Mutat. Res. 1999; 435: 103-109Crossref PubMed Scopus (59) Google Scholar, 49Auerbach A.D. Wolman S.R. Nature. 1976; 261: 494-496Crossref PubMed Scopus (277) Google Scholar, 50Gruenert D.C. Cleaver J.E. Cancer Res. 1985; 45: 5399-5404PubMed Google Scholar). Thus, the cancer predisposition that characterizes this disorder could result from chromosomal rearrangements is due to defective repair of chromosome double strand breaks that arise spontaneously or are created as intermediates in normal cellular processes. Likewise, just as defective repair of spontaneous DNA double strand breaks caused by oxygen is responsible for the neuronal apoptosis observed in knock-out mice lacking a functional non-homologous end-joining pathway (51Karanjawala Z.E. Murphy N. Hinton D.R. Hsieh C.-L. Lieber M.R. Curr. Biol. 2002; 12: 397-402Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar), the defective DNA double strand break repair we observe in FA cells could be responsible for bone marrow failure observed in these patients. Therefore, one exciting possibility is that pharmacological approaches may be developed to activate the defective DNA double strand break repair pathway in FA cells. Such therapeutic intervention could potentially halt the inexorable loss of bone marrow stem cells that results in fatal anemia in these patients, thereby extending their life span. Fanconi anemia (FA) 1The abbreviations used for: FA, Fanconi anemia; SRB, sulforhodamine B. 1The abbreviations used for: FA, Fanconi anemia; SRB, sulforhodamine B. is a fatal inherited autosomal recessive disease characterized by progressive bone marrow failure and a significant predisposition toward malignancies, particularly acute myelogenous leukemia (1Auerbach A.D. Allen R.G. Cancer Genet. Cytogenet. 1991; 51: 1-12Abstract Full Text PDF PubMed Scopus (248) Google Scholar, 2D'Andrea A.D. Grompe M. Blood. 1997; 90: 1725-1736Crossref PubMed Google Scholar). Somatic cell hybridization studies have shown that abnormalities in multiple genes result in FA (3Joenje H. Oostra A.B. Wijker M. di Summa F.M. van Berkel C.G. Rooimans M.A. Ebell W. van Weel M. Pronk J.C. Buchwald M. Arwert F. Am. J. Hum. Genet. 1997; 61: 940-944Abstract Full Text PDF PubMed Scopus (252) Google Scholar, 4Joenje H. Levitus M. Waisfisz Q. D'Andrea A.D. Garcia-Higuera I. Pearson T. van Berkel C.G. Rooimans M.A. Morgan N. Mathew C.G. Arwert F. Am. J. Hum. Genet. 2000; 67: 759-762Abstract Full Text Full Text PDF PubMed Scopus (101) Google Scholar, 5Timmers C. Taniguchi T. Hejna J. Reifsteck C. Lucas L. Bruun D. Thayer M. Cox B. Olson S. D'Andrea A.D. Moses R. Grompe M. Mol. Cell. 2001; 7: 241-248Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar). To date, at least eight distinct complementation groups have been identified (A, B, C, D1, D2, E, F, and G), and all of the known FA genes have been cloned (6Strathdee C.A. Gavish H. Shannon W.R. Buchwald M. Nature. 1992; 356: 763-767Crossref PubMed Scopus (534) Google Scholar, 7The Fanconi anaemia/Breast Cancer Consortium. Nat. Genet. 1996; 14: 324-328Crossref PubMed Scopus (261) Google Scholar, 8Lo Ten Foe J.R. Rooimans M.A. Bosnoyan-Collins L. Alon N. Wijker M. Parker L. Lightfoot J. Carreau M. Callen D.F. Savoia A. Cheng N.C. van Berkel C.G. Strunk M.H. Gille J.J. Pals G. Kruyt F.A. Pronk J.C. Arwert F. Buchwald M. Joenje H. Nat. Genet. 1996; 14: 320-323Crossref PubMed Scopus (300) Google Scholar, 9de Winter J.P. Waisfisz Q. Rooimans M.A. van Berkel C.G.M. Bosnoyan-Collins L. Alon N. Carreau M. Bender O. Demuth I. Schindler D. Pronk J.C. Arwert F. Hoehn H. Digweed M. Buchwald M. Joenje H. Nat. Genet. 1998; 20: 281-283Crossref PubMed Scopus (282) Google Scholar, 10de Winter J.P. Leveille F. van Berkel C.G.M. Rooimans M.A. van der Weel L. Steltenpool J. Demuth I. Morgan N.V. Alon N. Bosnoyan-Collins L. Lightfoot J. Leegwater P.A. Waisfisz Q. Komatsu K. Arwert F. Pronk J.C. Mathew C.G. Digweed M. Buchwald M. Joenje J. Am. J. Hum. Genet. 2000; 67: 1306-1308Abstract Full Text Full Text PDF PubMed Scopus (190) Google Scholar, 11de Winter J.P. Rooimans M.A. van der Weel L. van Berkel C.G.M. Alon N. Bosnoyan-Collins L. de Groot J. Zhi Y. Waisfisz Q. Pronk J.C. Arwert F. Mathew C.G. Scheper R.J. Nat. Genet. 2000; 24: 15-16Crossref PubMed Scopus (234) Google Scholar, 12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar). With the exception of FANCB, and FANCD1, none of the FA genes contains sequence motifs of known function (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar), and onlyFANCD2 has been found to have a homolog in lower eukaryotic organisms (5Timmers C. Taniguchi T. Hejna J. Reifsteck C. Lucas L. Bruun D. Thayer M. Cox B. Olson S. D'Andrea A.D. Moses R. Grompe M. Mol. Cell. 2001; 7: 241-248Abstract Full Text Full Text PDF PubMed Scopus (330) Google Scholar). Some of the FA genes encode proteins that interact to form a complex in the nucleus. This complex is disrupted in cell lines from complementation groups A, C, E, F, and G (13de Winter J.P. van der Weel L. de Groot J. Stone S. Waisfisz Q. Arwert F. Scheper R.J. Kruyt F.A.E. Hoatlin M.E. Joenje H. Hum. Mol. Genet. 2000; 9: 2665-2674Crossref PubMed Scopus (172) Google Scholar, 14Medhurst A.L. Huber P.A. Waisfisz Q. de Winter J.P. Mathew C.G. Hum. Mol. Genet. 2001; 10: 423-429Crossref PubMed Scopus (140) Google Scholar). Yet despite these findings, the exact biological functions of the FA proteins have not yet been determined and the molecular mechanism(s) responsible for FA have remained obscure (15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar). Interestingly, although the molecular defect responsible for FA is unclear, it has been well documented that cells from FA patients display elevated levels of spontaneous chromosomal breaks and deletions and have an increased sensitivity to the cytotoxic and clastogenic effects of DNA cross-linking agents (16Ishida R. Buchwald M. Cancer Res. 1982; 42: 4000-4006PubMed Google Scholar, 17Papadopoulo D. Guillouf C. Mohrenweiser H. Moustacchi E. Proc. Natl. Acad. Sci. U. S. A. 1990; 87: 8383-8387Crossref PubMed Scopus (109) Google Scholar, 18Auerbach A.D. Exp. Hematol. 1993; 21: 731-733PubMed Google Scholar, 19Carreau M. Alon N. Bosnoyan-Collins L. Joenje H. Buchwald M. Mutat. Res. 1999; 435: 103-109Crossref PubMed Scopus (59) Google Scholar). Patient-derived FA lymphoblasts have been shown to have significantly decreased plasmid-rejoining fidelity compared with normal lymphoblasts (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar). Additionally, nuclear extracts from patient-derived FA fibroblasts have substantially decreased plasmid-rejoining activity compared with extracts from normal fibroblasts (22Lundberg R. Mavinakere M. Campbell C. J. Biol. Chem. 2001; 276: 9543-9549Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar). These cellular features along with the high susceptibility of FA patients to cancers have lead to the hypothesis that this disorder results from defective DNA repair. However, the absence of recognizable DNA binding sequence motifs in FA genes and the lack of evidence showing direct interaction of FA gene products with DNA cast doubt on the idea that FA proteins directly participate in DNA repair. Recent results demonstrating a connection between the BRCA1 and BRCA2 tumor suppressor and FA proteins suggest that FA proteins may play an essential role in regulating the cellular response to DNA damage (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar, 15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar, 23Patel K.J. Yu V.P. Lee H. Coircoran A. Thistlethwaite F.C. Evans M.J. Colledge W.H. Friedman L.S. Ponder B.A. Venkitaraman A.R. Mol. Cell. 1998; 1: 347-357Abstract Full Text Full Text PDF PubMed Scopus (520) Google Scholar, 24Garcia-Higuera I. Taniguchi T. Ganesan S. Meyn M.S. Timmers C. Hejna J. Grompe M. D'Andrea A.D. Mol. Cell. 2001; 7: 249-262Abstract Full Text Full Text PDF PubMed Scopus (1019) Google Scholar, 25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). We examined both extra-chromosomal and chromosomal DNA repair in intact FA fibroblasts and retrovirally corrected FA fibroblasts from multiple complementation groups and animal models. We found that fibroblasts derived from FA patients of complementation groups A, C, D2, and G were significantly deficient in the repair of both plasmid and chromosome DNA double strand breaks and that this deficiency was corrected by the expression of the respective FA cDNAs in these cells. Furthermore, a similar defect in DNA double strand break repair was seen in cells derived from two rodent models of FA and in wild type cells expressing a dominant negative FANCC allele. DISCUSSIONThe data presented herein support the conclusion that FA fibroblasts have a dramatically reduced ability to rejoin double strand breaks in both introduced plasmids as well as within their chromosomes. These defects were observed in diploid fibroblasts from patients whose cells belong to a number of different FA complementation groups. In all cases tested, the re-introduction of the deficient FA gene into these cells eliminated the aberrant phenotype. An inability to repair restriction enzyme-induced chromosomal double strand breaks was also observed in two different rodent models of FA as well as in a human cell culture model of FA induced by overexpression of a dominant negative allele of the FANCC gene. Taken together, these findings provide robust support for the conclusion that FA fibroblasts have a defect in cellular DNA double strand break repair.The nature of the DNA double strand break repair defect in FA fibroblasts, however, remains obscure. It is known that mammalian cells use both recombinational and non-homologous end-joining pathways to repair DNA double strand breaks. Thus, in principle, either mechanism or conceivably both could be affected in FA fibroblasts. It is not likely that the linearized plasmid substrates utilized in our end-joining assays are repaired via a recombinational mechanism. Thus, we can conclude that FA fibroblasts have a defect in a non-recombinational DNA double strand break repair pathway. The findings that V(D)J recombination and Ku-dependent non-homologous end-joining are not affected in FA cells (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 22Lundberg R. Mavinakere M. Campbell C. J. Biol. Chem. 2001; 276: 9543-9549Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar, 37Smith J. Andrau J.C. Kallenbach S. Laquerbe A. Doyen N. Papadopoulo D. J. Mol. Biol. 1998; 281: 815-825Crossref PubMed Scopus (38) Google Scholar) indicate that this observed defect does not involve these pathways. Instead, it appears that the deficiency resides in another currently uncharacterized non-recombinational repair pathway.It is tempting to speculate that the hypersensitivity of FA fibroblasts to restriction enzyme-induced chromosomal double strand breaks is a consequence of deficient non-recombinational repair of these lesions. However, a number of findings suggest that this hypersensitivity could reflect a deficiency in chromosomal homologous recombinational repair. First, the BRCA1 protein, which is required for efficient recombinational repair of chromosome double strand breaks, co-localizes to nuclear foci with the FANCD2 protein in cells following exposure to ionizing radiation (24Garcia-Higuera I. Taniguchi T. Ganesan S. Meyn M.S. Timmers C. Hejna J. Grompe M. D'Andrea A.D. Mol. Cell. 2001; 7: 249-262Abstract Full Text Full Text PDF PubMed Scopus (1019) Google Scholar). FANCD2 has also been shown to be phosphorylated in an ATM-dependent manner following induced DNA damage (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). Second, the FANCB andFANCD1 genes are apparently identical to BRCA2, a gene also required for efficient recombinational repair of chromosome double strand breaks (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar, 15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar, 38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar). Third, both the BRCA1 and BRCA2 proteins interact with the mammalian RecA homolog Rad51 (39Venkitaraman A.R. J. Cell Sci. 2001; 114: 3591-3598PubMed Google Scholar), and cells deficient in BRCA1 and/or BRCA2 have a significant defect in homologous recombination, display chromosomal instability, and are hypersensitive to DNA cross-linking agents as are FA cells (38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar, 40Jachymczyk W.J. von Borstel R.C. Mowat M.R. Hastings P.J. Mol. Gen. Genet. 1981; 182: 196-205Crossref PubMed Scopus (158) Google Scholar, 41Caldecott K. Jeggo P.A. Mutat. Res. 1991; 255: 111-121Crossref PubMed Scopus (132) Google Scholar, 42Liu N. Lamerdin J.E. Tebbs R.S. Schild D. Tucker J.D. Shen M.R. Brookman K.W. Siciliano M.J. Walter C.A. Fan W. Narayana L.S. Zhou Z.Q. Adamson A.W. Sorensen K.J. Chen D.J. Jones N.J. Thompson L.H. Mol. Cell. 1998; 1: 783-793Abstract Full Text Full Text PDF PubMed Scopus (470) Google Scholar, 43Scully R. Chen J. Ochs R.L. Keegan K. Hoekstra M. Feunteun J. Livingston D.M. Cell. 1997; 90: 425-435Abstract Full Text Full Text PDF PubMed Scopus (806) Google Scholar, 44Snouwaert J.N. Gowen L.C. Latour A.M. Mohn A.R. Xiao A. DiBiase L. Koller B.H. Oncogene. 1999; 18: 7900-7907Crossref PubMed Scopus (165) Google Scholar, 45Moynahan M.E. Cui T.Y. Jasin M. Cancer Res. 2001; 61: 4842-4850PubMed Google Scholar). Thus, it is conceivable that FA cells have a defect in recombinational repair of chromosomal DNA double strand breaks. It remains to be determined whether the elevated sensitivity of FA cells to restriction enzyme-induced cell death is a consequence of defective non-homologous end-joining, defective recombinational repair, or both. It may be possible to gain insight into this question by studying the repair of double strand breaks induced into engineered chromosomal loci by rare-cutting endonucleases such as the yeast I SceI enzyme.An alternative explanation for the cytotoxicity observed in FA fibroblasts following introduction of restriction enzymes is that cell death may be due to improper checkpoint regulation following chromosomal damage. A recent report by Taniguchi et al. (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar) shows that FANCD2 fibroblasts have radio-resistant DNA synthesis following induced DNA damage. Similarly, BRCA2/FANCD1-deficient Chinese hamster ovary cells and BRCA1-deficient cells also display radio-resistant DNA synthesis after exposure to ionizing radiation (46Kraakman-van der Zwet M. Overkamp W.J.I. van Lange R.E.E. Essers J. van Duijn-Goedhart A. Wiggers I. Swaminathan S. van Buul P.P.W. Errami A. Tan R.T.L. Jaspers N.G.J. Sharan S.K. Kanaar R. Zdzienicka M.Z. Mol. Cell. Biol. 2002; 22: 669-679Crossref PubMed Scopus (228) Google Scholar,47Xu B. Kim S. Kastan M.B. Mol. Cell. Biol. 2001; 21: 3445-3450Crossref PubMed Scopus (470) Google Scholar). Thus, given the association among FA proteins and BRCA1 and BRCA2 previously outlined, these data indicate that FA cells may have an S phase checkpoint defect. Failed repair of DNA double strand breaks and an inability to regulate an essential checkpoint may result in these FA cells progressing through the cell cycle with unrepaired chromosomal lesions that would ultimately lead to cell death.Regardless of the nature of the defect, the deficiency in DNA double strand break repair observed in FA fibroblasts may provide an attractive explanation for some of the pathologies associated with FA. Although this conclusion is derived from studies performed on fibroblast cells and may not be applicable to all cell types, evidence from lymphoblasts derived from FA patients also indicates a deficiency in DNA double strand break repair (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 48Runger T.M. Sobotta P. Dekant B. Moller K. Bauer C. Kraemer K.H. Toxicol Lett. 1993; 67: 309-324Crossref PubMed Scopus (13) Google Scholar). Additionally, an examination of both fibroblasts and lymphoblasts derived from FA patients has revealed no distinct differences in sensitivities to DNA-damaging agents or chromosomal instability, the two main cellular features of FA (16Ishida R. Buchwald M. Cancer Res. 1982; 42: 4000-4006PubMed Google Scholar, 19Carreau M. Alon N. Bosnoyan-Collins L. Joenje H. Buchwald M. Mutat. Res. 1999; 435: 103-109Crossref PubMed Scopus (59) Google Scholar, 49Auerbach A.D. Wolman S.R. Nature. 1976; 261: 494-496Crossref PubMed Scopus (277) Google Scholar, 50Gruenert D.C. Cleaver J.E. Cancer Res. 1985; 45: 5399-5404PubMed Google Scholar). Thus, the cancer predisposition that characterizes this disorder could result from chromosomal rearrangements is due to defective repair of chromosome double strand breaks that arise spontaneously or are created as intermediates in normal cellular processes. Likewise, just as defective repair of spontaneous DNA double strand breaks caused by oxygen is responsible for the neuronal apoptosis observed in knock-out mice lacking a functional non-homologous end-joining pathway (51Karanjawala Z.E. Murphy N. Hinton D.R. Hsieh C.-L. Lieber M.R. Curr. Biol. 2002; 12: 397-402Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar), the defective DNA double strand break repair we observe in FA cells could be responsible for bone marrow failure observed in these patients. Therefore, one exciting possibility is that pharmacological approaches may be developed to activate the defective DNA double strand break repair pathway in FA cells. Such therapeutic intervention could potentially halt the inexorable loss of bone marrow stem cells that results in fatal anemia in these patients, thereby extending their life span. The data presented herein support the conclusion that FA fibroblasts have a dramatically reduced ability to rejoin double strand breaks in both introduced plasmids as well as within their chromosomes. These defects were observed in diploid fibroblasts from patients whose cells belong to a number of different FA complementation groups. In all cases tested, the re-introduction of the deficient FA gene into these cells eliminated the aberrant phenotype. An inability to repair restriction enzyme-induced chromosomal double strand breaks was also observed in two different rodent models of FA as well as in a human cell culture model of FA induced by overexpression of a dominant negative allele of the FANCC gene. Taken together, these findings provide robust support for the conclusion that FA fibroblasts have a defect in cellular DNA double strand break repair. The nature of the DNA double strand break repair defect in FA fibroblasts, however, remains obscure. It is known that mammalian cells use both recombinational and non-homologous end-joining pathways to repair DNA double strand breaks. Thus, in principle, either mechanism or conceivably both could be affected in FA fibroblasts. It is not likely that the linearized plasmid substrates utilized in our end-joining assays are repaired via a recombinational mechanism. Thus, we can conclude that FA fibroblasts have a defect in a non-recombinational DNA double strand break repair pathway. The findings that V(D)J recombination and Ku-dependent non-homologous end-joining are not affected in FA cells (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 22Lundberg R. Mavinakere M. Campbell C. J. Biol. Chem. 2001; 276: 9543-9549Abstract Full Text Full Text PDF PubMed Scopus (55) Google Scholar, 37Smith J. Andrau J.C. Kallenbach S. Laquerbe A. Doyen N. Papadopoulo D. J. Mol. Biol. 1998; 281: 815-825Crossref PubMed Scopus (38) Google Scholar) indicate that this observed defect does not involve these pathways. Instead, it appears that the deficiency resides in another currently uncharacterized non-recombinational repair pathway. It is tempting to speculate that the hypersensitivity of FA fibroblasts to restriction enzyme-induced chromosomal double strand breaks is a consequence of deficient non-recombinational repair of these lesions. However, a number of findings suggest that this hypersensitivity could reflect a deficiency in chromosomal homologous recombinational repair. First, the BRCA1 protein, which is required for efficient recombinational repair of chromosome double strand breaks, co-localizes to nuclear foci with the FANCD2 protein in cells following exposure to ionizing radiation (24Garcia-Higuera I. Taniguchi T. Ganesan S. Meyn M.S. Timmers C. Hejna J. Grompe M. D'Andrea A.D. Mol. Cell. 2001; 7: 249-262Abstract Full Text Full Text PDF PubMed Scopus (1019) Google Scholar). FANCD2 has also been shown to be phosphorylated in an ATM-dependent manner following induced DNA damage (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar). Second, the FANCB andFANCD1 genes are apparently identical to BRCA2, a gene also required for efficient recombinational repair of chromosome double strand breaks (12Howlett N.G. Taniguchi T. Olson S. Cox B. Waisfisz Q. de Die-Smulders C. Persky N. Grompe M. Joenje H. Pals G. Ikeda H. Fox E.A. D'Andrea A.D. Science. 2002; 297: 606-609Crossref PubMed Scopus (955) Google Scholar, 15Witt E. Ashworth A. Science. 2002; 297: 534Crossref PubMed Scopus (13) Google Scholar, 38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar). Third, both the BRCA1 and BRCA2 proteins interact with the mammalian RecA homolog Rad51 (39Venkitaraman A.R. J. Cell Sci. 2001; 114: 3591-3598PubMed Google Scholar), and cells deficient in BRCA1 and/or BRCA2 have a significant defect in homologous recombination, display chromosomal instability, and are hypersensitive to DNA cross-linking agents as are FA cells (38Moynahan M.E. Pierce A.J. Jasin M. Mol. Cell. 2001; 7: 263-272Abstract Full Text Full Text PDF PubMed Scopus (757) Google Scholar, 40Jachymczyk W.J. von Borstel R.C. Mowat M.R. Hastings P.J. Mol. Gen. Genet. 1981; 182: 196-205Crossref PubMed Scopus (158) Google Scholar, 41Caldecott K. Jeggo P.A. Mutat. Res. 1991; 255: 111-121Crossref PubMed Scopus (132) Google Scholar, 42Liu N. Lamerdin J.E. Tebbs R.S. Schild D. Tucker J.D. Shen M.R. Brookman K.W. Siciliano M.J. Walter C.A. Fan W. Narayana L.S. Zhou Z.Q. Adamson A.W. Sorensen K.J. Chen D.J. Jones N.J. Thompson L.H. Mol. Cell. 1998; 1: 783-793Abstract Full Text Full Text PDF PubMed Scopus (470) Google Scholar, 43Scully R. Chen J. Ochs R.L. Keegan K. Hoekstra M. Feunteun J. Livingston D.M. Cell. 1997; 90: 425-435Abstract Full Text Full Text PDF PubMed Scopus (806) Google Scholar, 44Snouwaert J.N. Gowen L.C. Latour A.M. Mohn A.R. Xiao A. DiBiase L. Koller B.H. Oncogene. 1999; 18: 7900-7907Crossref PubMed Scopus (165) Google Scholar, 45Moynahan M.E. Cui T.Y. Jasin M. Cancer Res. 2001; 61: 4842-4850PubMed Google Scholar). Thus, it is conceivable that FA cells have a defect in recombinational repair of chromosomal DNA double strand breaks. It remains to be determined whether the elevated sensitivity of FA cells to restriction enzyme-induced cell death is a consequence of defective non-homologous end-joining, defective recombinational repair, or both. It may be possible to gain insight into this question by studying the repair of double strand breaks induced into engineered chromosomal loci by rare-cutting endonucleases such as the yeast I SceI enzyme. An alternative explanation for the cytotoxicity observed in FA fibroblasts following introduction of restriction enzymes is that cell death may be due to improper checkpoint regulation following chromosomal damage. A recent report by Taniguchi et al. (25Taniguchi T. Garcia-Higuera I. Xu B. Andeassen P.R. Gregory R.C. Kim S.-T. Lane W.S. Kastan M.B. D'Andrea A.D. Cell. 2002; 109: 459-472Abstract Full Text Full Text PDF PubMed Scopus (378) Google Scholar) shows that FANCD2 fibroblasts have radio-resistant DNA synthesis following induced DNA damage. Similarly, BRCA2/FANCD1-deficient Chinese hamster ovary cells and BRCA1-deficient cells also display radio-resistant DNA synthesis after exposure to ionizing radiation (46Kraakman-van der Zwet M. Overkamp W.J.I. van Lange R.E.E. Essers J. van Duijn-Goedhart A. Wiggers I. Swaminathan S. van Buul P.P.W. Errami A. Tan R.T.L. Jaspers N.G.J. Sharan S.K. Kanaar R. Zdzienicka M.Z. Mol. Cell. Biol. 2002; 22: 669-679Crossref PubMed Scopus (228) Google Scholar,47Xu B. Kim S. Kastan M.B. Mol. Cell. Biol. 2001; 21: 3445-3450Crossref PubMed Scopus (470) Google Scholar). Thus, given the association among FA proteins and BRCA1 and BRCA2 previously outlined, these data indicate that FA cells may have an S phase checkpoint defect. Failed repair of DNA double strand breaks and an inability to regulate an essential checkpoint may result in these FA cells progressing through the cell cycle with unrepaired chromosomal lesions that would ultimately lead to cell death. Regardless of the nature of the defect, the deficiency in DNA double strand break repair observed in FA fibroblasts may provide an attractive explanation for some of the pathologies associated with FA. Although this conclusion is derived from studies performed on fibroblast cells and may not be applicable to all cell types, evidence from lymphoblasts derived from FA patients also indicates a deficiency in DNA double strand break repair (20Escarceller M. Rousset S. Moustacchi E. Papadopoulo D. Somatic Cell Mol. Genet. 1997; 23: 401-411Crossref PubMed Scopus (41) Google Scholar, 21Escarceller M. Buchwald M. Singleton B.K. Jeggo P.A. Jackson S.P. Moustacchi E. Papadopoulo D. J. Mol. Biol. 1998; 279: 375-385Crossref PubMed Scopus (73) Google Scholar, 48Runger T.M. Sobotta P. Dekant B. Moller K. Bauer C. Kraemer K.H. Toxicol Lett. 1993; 67: 309-324Crossref PubMed Scopus (13) Google Scholar). Additionally, an examination of both fibroblasts and lymphoblasts derived from FA patients has revealed no distinct differences in sensitivities to DNA-damaging agents or chromosomal instability, the two main cellular features of FA (16Ishida R. Buchwald M. Cancer Res. 1982; 42: 4000-4006PubMed Google Scholar, 19Carreau M. Alon N. Bosnoyan-Collins L. Joenje H. Buchwald M. Mutat. Res. 1999; 435: 103-109Crossref PubMed Scopus (59) Google Scholar, 49Auerbach A.D. Wolman S.R. Nature. 1976; 261: 494-496Crossref PubMed Scopus (277) Google Scholar, 50Gruenert D.C. Cleaver J.E. Cancer Res. 1985; 45: 5399-5404PubMed Google Scholar). Thus, the cancer predisposition that characterizes this disorder could result from chromosomal rearrangements is due to defective repair of chromosome double strand breaks that arise spontaneously or are created as intermediates in normal cellular processes. Likewise, just as defective repair of spontaneous DNA double strand breaks caused by oxygen is responsible for the neuronal apoptosis observed in knock-out mice lacking a functional non-homologous end-joining pathway (51Karanjawala Z.E. Murphy N. Hinton D.R. Hsieh C.-L. Lieber M.R. Curr. Biol. 2002; 12: 397-402Abstract Full Text Full Text PDF PubMed Scopus (157) Google Scholar), the defective DNA double strand break repair we observe in FA cells could be responsible for bone marrow failure observed in these patients. Therefore, one exciting possibility is that pharmacological approaches may be developed to activate the defective DNA double strand break repair pathway in FA cells. Such therapeutic intervention could potentially halt the inexorable loss of bone marrow stem cells that results in fatal anemia in these patients, thereby extending their life span. We thank Drs. Larry H. Thompson, Maureen E. Hoatlin, and Barbara Cox for kindly providing reagents used herein." @default.
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W1990997564 title "A DNA Double Strand Break Repair Defect in Fanconi Anemia Fibroblasts" @default.
W1990997564 cites W1495571943 @default.
W1990997564 cites W1507694958 @default.
W1990997564 cites W1549538719 @default.
W1990997564 cites W1590550062 @default.
W1990997564 cites W1947648770 @default.
W1990997564 cites W1979305633 @default.
W1990997564 cites W1980946002 @default.
W1990997564 cites W1991841649 @default.
W1990997564 cites W1997104526 @default.
W1990997564 cites W1997197881 @default.
W1990997564 cites W2002555966 @default.
W1990997564 cites W2004917731 @default.
W1990997564 cites W2013261546 @default.
W1990997564 cites W2014753858 @default.
W1990997564 cites W2015626211 @default.
W1990997564 cites W2024954071 @default.
W1990997564 cites W2025301695 @default.
W1990997564 cites W2025563609 @default.
W1990997564 cites W2030705116 @default.
W1990997564 cites W2038936226 @default.
W1990997564 cites W2039435798 @default.
W1990997564 cites W2040620741 @default.
W1990997564 cites W2044329004 @default.
W1990997564 cites W2048590349 @default.
W1990997564 cites W2054965243 @default.
W1990997564 cites W2057523734 @default.
W1990997564 cites W2065417936 @default.
W1990997564 cites W2066108933 @default.
W1990997564 cites W2072397306 @default.
W1990997564 cites W2075629733 @default.
W1990997564 cites W2084259798 @default.
W1990997564 cites W2087505934 @default.
W1990997564 cites W2092873195 @default.
W1990997564 cites W2098697121 @default.
W1990997564 cites W2101161126 @default.
W1990997564 cites W2109689528 @default.
W1990997564 cites W2126854245 @default.
W1990997564 cites W2134536765 @default.
W1990997564 cites W2139554694 @default.
W1990997564 cites W2147126714 @default.
W1990997564 cites W2156168452 @default.
W1990997564 cites W2161854614 @default.
W1990997564 cites W2163599181 @default.
W1990997564 cites W2168225429 @default.
W1990997564 cites W4250964040 @default.
W1990997564 cites W4302183079 @default.
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