Cockayne Syndrome Group B Protein Stimulates Repair of Formamidopyrimidines by NEIL1 DNA Glycosylase
Cockayne syndrome (CS) is a premature aging condition characterized by sensitivity to UV radiation. However, this phenotype does not explain the progressive neurodegeneration in CS patients. It could be due to the hypersensitivity of CSB-deficient cells to oxidative stress. So far most studies on the role of CSB in repair of oxidatively induced DNA lesions have focused on 7,8-dihydro-8-oxoguanine. This study examines the role of CSB in the repair of formamidopyrimidines 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde), which are substrates for endonuclease VIII-like (NEIL1) DNA glycosylase. Results presented here show that csb-/- mice have a higher level of endogenous FapyAde and FapyGua in DNA from brain and kidney than wild type mice as well as higher levels of endogenous FapyAde in genomic DNA and mtDNA from liver. In addition, CSB stimulates NEIL1 incision activity in vitro, and CSB and NEIL1 co-immunoprecipitate and co-localize in HeLa cells. When CSB and NEIL1 are depleted from HeLa cells by short hairpin RNA knockdown, repair of induced FapyGua is strongly inhibited. These results suggest that CSB plays a role in repair of formamidopyrimidines, possibly by interacting with and stimulating NEIL1, and that accumulation of such modifications may have a causal role in the pathogenesis of CS. Cockayne syndrome (CS) is a premature aging condition characterized by sensitivity to UV radiation. However, this phenotype does not explain the progressive neurodegeneration in CS patients. It could be due to the hypersensitivity of CSB-deficient cells to oxidative stress. So far most studies on the role of CSB in repair of oxidatively induced DNA lesions have focused on 7,8-dihydro-8-oxoguanine. This study examines the role of CSB in the repair of formamidopyrimidines 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine (FapyAde), which are substrates for endonuclease VIII-like (NEIL1) DNA glycosylase. Results presented here show that csb-/- mice have a higher level of endogenous FapyAde and FapyGua in DNA from brain and kidney than wild type mice as well as higher levels of endogenous FapyAde in genomic DNA and mtDNA from liver. In addition, CSB stimulates NEIL1 incision activity in vitro, and CSB and NEIL1 co-immunoprecipitate and co-localize in HeLa cells. When CSB and NEIL1 are depleted from HeLa cells by short hairpin RNA knockdown, repair of induced FapyGua is strongly inhibited. These results suggest that CSB plays a role in repair of formamidopyrimidines, possibly by interacting with and stimulating NEIL1, and that accumulation of such modifications may have a causal role in the pathogenesis of CS. Cockayne syndrome (CS) 6The abbreviations used are: CS, cockayne syndrome; BER, base excision repair; OGG1, 8-oxoguanine DNA glycosylase; 8-OH-Gua, 7,8-dihydro-8-oxoguanine; PARP1, poly(ADP-ribose) polymerase; Fpg, formamidopyrimidine DNA glycosylase; shRNA, short hairpin RNA; GC, gas chromatography; MS, mass spectrometry; LC, liquid chromatography; 5-OH-Ura, 5-hydroxyuracil; ssDNA, single-stranded DNA; Fapy, formamidopyrimidine; FapyGua, 2,6-diamino-4-hydroxy-5-Fapy; FapyAde, 4,6-diamino-5-Fapy; PBS, phosphate-buffered saline; wt, wild type; Bis-Tris, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol; CSBfl, full-length CSB; AP, apurinic or apyrimidinic. is a segmental premature aging syndrome with progressive neurological degeneration (1Rapin I. Lindenbaum Y. Dickson D.W. Kraemer K.H. Robbins J.H. Neurology. 2000; 55: 1442-1449Crossref PubMed Scopus (185) Google Scholar). CS is caused by mutations in CS complementation groups A (CSA) or B (CSB) genes (2Tanaka K. Kawai K. Kumahara Y. Ikenaga M. Okada Y. Somatic Cell Genet. 1981; 7: 445-455Crossref PubMed Scopus (78) Google Scholar, 3Stefanini M. Fawcett H. Botta E. Nardo T. Lehmann A.R. Hum. Genet. 1996; 97: 418-423Crossref PubMed Scopus (76) Google Scholar). Approximately 80% of CS patients have mutations in the CSB gene, which encodes a 168-kDa protein belonging to the SWI/SNF2 family of chromatin remodeling proteins (4Troelstra C. Odijk H. de Wit J. Westerveld A. Thompson L.H. Bootsma D. Hoeijmakers J.H. Mol. Cell. Biol. 1990; 10: 5806-5813Crossref PubMed Scopus (109) Google Scholar). Cells from CS patients are hypersensitive to UV radiation-induced DNA damage, and the CSB protein is required for the transcription-coupled nucleotide excision repair of UV radiation-induced DNA lesions (cyclobutane pyrimidine dimers and 6-pyrimidine-4-pyrimidone products) (5van Oosterwijk M.F. Versteeg A. Filon R. van Zeeland A.A. Mullenders L.H. Mol. Cell. Biol. 1996; 16: 4436-4444Crossref PubMed Scopus (87) Google Scholar). CSB is also believed to play a role in transcription elongation and interacts with the RNA polymerase II elongation complex (6Iyer N. Reagan M.S. Wu K.J. Canagarajah B. Friedberg E.C. Biochemistry. 1996; 35: 2157-2167Crossref PubMed Scopus (167) Google Scholar). The molecular basis of the progressive neurological defects in CS patients, however, remains unknown; it has been proposed that neurological symptoms in CS may be due to defective repair and/or processing of oxidative DNA damage in CSB-deficient cells (7Kraemer K.H. Patronas N.J. Schiffmann R. Brooks B.P. Tamura D. DiGiovanna J.J. Neuroscience. 2007; 145: 1388-1396Crossref PubMed Scopus (305) Google Scholar). Oxidative DNA damage can be caused by endogenous and exogenous agents. Reactive oxygen species, including highly reactive hydroxyl radicals, are formed as byproducts of normal metabolism, mostly during the process of mitochondrial respiration. It has been estimated that up to 2% of all the O2 consumed by respiration may be released as reactive oxygen species (8Nohl H. Gille L. Staniek K. Biochem. Pharmacol. 2005; 69: 719-723Crossref PubMed Scopus (190) Google Scholar, 9Raha S. Robinson B.H. Am. J. Med. Genet. 2001; 106: 62-70Crossref PubMed Scopus (257) Google Scholar). The central nervous system relies exclusively on mitochondria to generate ATP through oxidative metabolism. As a result, neurons are susceptible to increased levels of oxidative stress, and elevated levels of reactive oxygen species have been implicated in the etiology of neurodegenerative diseases including Alzheimer, Parkinson, and Huntington diseases and amyotrophic lateral sclerosis (for a review, see Ref. 10Mattson M.P. Liu D. Neuromolecular Med. 2002; 2: 215-231Crossref PubMed Scopus (180) Google Scholar). Hydroxyl radicals attack DNA bases and the sugar-phosphate DNA backbone, generating modified bases and single-stranded DNA (ssDNA) breaks, respectively (11Evans M.D. Dizdaroglu M. Cooke M.S. Mutat. Res. 2004; 567: 1-61Crossref PubMed Scopus (1006) Google Scholar). Many oxidatively induced DNA lesions are mutagenic and/or cytotoxic and have been associated with aging, neurodegeneration, and carcinogenesis (for review, see Refs. 12de Souza-Pinto N.C. Bohr V.A. Int. Rev. Neurobiol. 2002; 53: 519-534Crossref PubMed Google Scholar and 13Loft S. Poulsen H.E. J. Mol. Med. 1996; 74: 297-312Crossref PubMed Scopus (822) Google Scholar). Most of these lesions are repaired by the base excision repair pathway (BER), during which lesion-specific DNA glycosylases hydrolyze the N-glycosidic bond between the modified base and the sugar moiety to release the modified base and generate an abasic (AP) site. Subsequent repair steps include cleavage of the resulting abasic site, incorporation of one or few nucleotides, trimming of the 5′ and 3′ ends, and ligation of the DNA backbone (14Wilson III, D.M. Sofinowski T.M. McNeill D.R. Front. Biosci. 2003; 8: 963-981Crossref PubMed Google Scholar). Several DNA glycosylases specifically recognize and repair oxidatively induced DNA lesions (15Ide H. Kotera M. Biol. Pharm. Bull. 2004; 27: 480-485Crossref PubMed Scopus Google Scholar). The of DNA glycosylases are in which may explain the of in mice 8-oxoguanine DNA or endonuclease In mice endonuclease VIII-like (NEIL1) DNA have a of syndrome B. S. S. A. PubMed Scopus (185) Google Scholar). This phenotype that NEIL1 is for repair of an endogenous DNA or lesions that has or that CSB may play a role in repair of oxidatively induced DNA from csb-/- mice are hypersensitive to and a that oxidative H. de J. van M. van Hoeijmakers J.H. van DNA 2003; 2: PubMed Scopus Google and cells CSB have defects in repair of and J. M. C. H. Dizdaroglu M. Bohr V.A. J. Biol. 2001; PubMed Scopus Google Scholar, J. H. Dizdaroglu M. Bohr V.A. J. Biol. 2002; PubMed Scopus Google Scholar). CSB is in a complex with OGG1, between the proteins has been J. C. M. Bohr V.A. DNA 2002; PubMed Scopus (87) Google Scholar). and kidney cells from mice higher levels of modified than csb-/- mice M. E. van S. A. B. 2002; PubMed Scopus Google and have elevated levels of mutations C. K. A. B. 2007; PubMed Scopus Google Scholar). CSB also interacts with including endonuclease M. Bohr V.A. III, D.M. Res. 2007; 35: PubMed Scopus Google and poly(ADP-ribose) polymerase T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google Scholar). Several studies have the role of CSB in repair of This however, may be a in it can be in the of and protein A E. E. B. 2007; PubMed Scopus Google Scholar). 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) and 4,6-diamino-5-formamidopyrimidine are of which a with and respectively (11Evans M.D. Dizdaroglu M. Cooke M.S. Mutat. Res. 2004; 567: 1-61Crossref PubMed Scopus (1006) Google Scholar, S. Rev. Scopus Google Scholar). FapyGua and FapyAde are the substrates of and NEIL1 M. Dizdaroglu M. Biochemistry. 2004; PubMed Scopus (76) Google Scholar, Dizdaroglu M. J. Biol. 2007; PubMed Scopus Google Scholar, T. I. B. Dizdaroglu M. S. S. A. 2002; PubMed Scopus Google and are in genomic DNA a higher level than J. de Souza-Pinto N.C. K. Dizdaroglu M. Bohr V.A. J. Biol. 2005; PubMed Scopus Google that accumulation of these lesions may be of in the of the phenotype in This study examines the role of CSB in repair of FapyGua and In studies show that endogenous in and kidney genomic DNA and mtDNA from csb-/- In studies show that CSB NEIL1 activity a of the CSB and NEIL1 also co-localize in HeLa cells and co-immunoprecipitate from HeLa hairpin of CSB and NEIL1 repair of These results suggest that NEIL1 and CSB in the repair of FapyAde and and CSB protein from cells as M. T. C. Bohr V.A. Res. 2003; PubMed Scopus Google Scholar). formamidopyrimidine DNA and as T. H. Dizdaroglu M. 2004; PubMed Scopus Google Scholar). NEIL1 protein by of Cell and cells in modified with and the cells with CSB NEIL1 or to the NEIL1 and cells and in and for levels of CSB and NEIL1 by The the levels of CSB and NEIL1 for the the and The cells to for the of the the the with PBS, and the cells for DNA or the and the cells for for the repair the with PBS, and the cells for DNA of and or mice by Hoeijmakers the type used as by and the and kidney and and mitochondrial as Souza-Pinto N.C. Bohr V.A. Biol. Med. 2001; PubMed Scopus Google Scholar). by the and and in with of for the and of of of of mtDNA and from and a of the Res. 16: PubMed Scopus Google Scholar). or from and kidney in of and The in to an protein of of and the of and proteins by for The and the DNA with of for The DNA by in of and with A for The to in for of proteins with and as DNA from the with by and in a by and DNA DNA in The DNA and in by the UV between and The and of 8-OH-Gua, FapyGua, and FapyAde in DNA by of DNA by E. T. H. Dizdaroglu M. 2004; PubMed Scopus Google Scholar, S. E. J. Dizdaroglu M. Biochemistry. PubMed Scopus Google Scholar). of DNA with of and as and with of as T. H. Dizdaroglu M. 2004; PubMed Scopus Google Scholar). DNA and by and by as T. H. Dizdaroglu M. 2004; PubMed Scopus Google Scholar). and used to the of 8-OH-Gua, FapyAde, and FapyGua and as M. PubMed Scopus Google Scholar). used to and as in DNA of DNA with an of as with and for and by as M. Dizdaroglu M. Biochemistry. 2004; PubMed Scopus (76) Google Scholar). and used to the of and M. H. Res. 2001; PubMed Scopus Google Scholar). The levels of with and of and results a with A to or than to be of the used here are in a from K. J. 2005; PubMed Scopus Google Scholar). The or from and as N.C. Bohr V.A. Res. 27: PubMed Scopus Google Scholar). and to the in and by the for and to used for incision The in the is and in a DNA for of FapyGua, FapyAde, 5-OH-Ura, or in a and of DNA for FapyAde, which The by NEIL1 and CSB as in the The for or and with the of of and of by of cleavage the abasic and for of and the for and by on a by and the The of incision as the of in the to the NEIL1 the as with DNA as for the with the of the of the for the by of and the for in The and the of CSB and CSB and as T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google Scholar). the the which encodes and and and The in E. and the and of and and of CSB wild type and as M. T. C. Bohr V.A. Res. 2003; PubMed Scopus Google Scholar, M. R. J. Bohr V.A. 2002; PubMed Scopus Google Scholar, S. J. A. M. M. E. Bohr V.A. Res. 2002; PubMed Scopus Google Scholar). as M. S. T. T. Bohr V.A. Res. PubMed Scopus Google and for with with of of or of as a for with for proteins by in for and by with or for by cells on and for Cells with and in in for The cells in and in in for on by in Cells for protein in for in and in and in in and for in and cells with used CSB and NEIL1 and for and between the by one and or from the and on a the the cells with the the and including than one as with or the for NEIL1 and with a than for NEIL1 and CSB as between the CSB and NEIL1 that than of of cells is presented with the level and the in of FapyGua, FapyAde, and in DNA from CSB has been proposed that oxidative DNA damage in CSB-deficient cells and that this plays a role in the of CS, in the of the central nervous However, studies specifically or to E. Fpg, which 8-OH-Gua, FapyGua, and FapyAde S. E. J. Dizdaroglu M. Biochemistry. PubMed Scopus Google Scholar). the endogenous levels of 8-OH-Gua, FapyGua, and FapyAde in and kidney genomic DNA and in mtDNA from or csb-/- mice by The results show that is a higher level in genomic DNA from brain and kidney of csb-/- than mice not in DNA FapyGua levels are also higher in brain and kidney from csb-/- mice FapyAde on the are higher in all of csb-/- mice The level of the of 8-OH-Gua, in DNA and results with that are to this studies also suggest a role for CSB in oxidative DNA damage in mitochondria T. S. de Souza-Pinto N.C. van T. Bohr V.A. 2002; PubMed Scopus (87) Google Scholar). In the study of mtDNA that FapyAde levels are higher in csb-/- mice than in mice that the levels of FapyGua and CSB of results presented suggest that FapyAde in in csb-/- FapyGua and 8-OH-Gua, not FapyAde, are substrates for C. Dizdaroglu M. S. Res. 27: PubMed Scopus Google Scholar). However, FapyAde and FapyGua are substrates for NEIL1 M. Dizdaroglu M. Biochemistry. 2004; PubMed Scopus (76) Google Scholar, Dizdaroglu M. J. Biol. 2007; PubMed Scopus Google Scholar, T. I. B. Dizdaroglu M. S. S. A. 2002; PubMed Scopus Google Scholar). This that NEIL1 activity may be in mice CSB and that CSB with NEIL1 in and processing This by NEIL1 incision in in the or of CSB substrates FapyGua, FapyAde, or NEIL1 a a FapyGua, generating the The of of CSB to NEIL1 incision activity up to and and However, higher of CSB increased NEIL1 incision activity a of the results with an a FapyAde The of the with NEIL1 the incision CSB NEIL1 FapyAde incision activity in a up to in a H. A. Y. I. S. J. Biol. PubMed Scopus Google that also interacts with and stimulates NEIL1 incision However, in that study NEIL1 incision activity up to a higher of H. S. Res. 2007; 35: PubMed Scopus Google a of NEIL1 by the complex a with a of show that of CSB to NEIL1 incision activity and that CSB does not FapyGua This that CSB does not have an activity does the CSB DNA These results that CSB stimulates incision activity of FapyGua in an of the to most DNA NEIL1 is on DNA lesions in ssDNA, in the of a single-stranded in a H. S. J. Biol. 2003; PubMed Scopus Google Scholar). of this it has been that NEIL1 plays a role during CSB also and is of the RNA polymerase II complex S. C. M. E. E. Mol. Cell. 2005; PubMed Scopus Google Scholar). the of CSB to NEIL1 activity a or a DNA a substrates the in the CSB NEIL1 incision activity on the in a and not on the and CSB of incision of this DNA also NEIL1 M. Dizdaroglu M. Biochemistry. 2004; PubMed Scopus (76) Google Scholar, Dizdaroglu M. J. Biol. 2007; PubMed Scopus Google Scholar, T. I. B. Dizdaroglu M. S. S. A. 2002; PubMed Scopus Google Scholar). that NEIL1 required to a of DNA substrates as FapyGua or In addition, up to a of CSB not incision of by NEIL1 The of the between NEIL1 and CSB by CSB stimulates the of E. to The results show that CSB does not incision of in and In in the that CSB NEIL1 incision activity and These results suggest that CSB is to NEIL1, and that which a of is not by CSB the of is a II DNA which cleavage of the bond and the resulting abasic to a activity Rev. Biochem. PubMed Scopus Google Scholar). The activity of NEIL1 a and a base between the and the DNA DNA including OGG1, these are J. Biol. 2000; PubMed Scopus (167) Google Scholar). CSB stimulates NEIL1 DNA and The of incision by the of which the abasic that CSB not one activity the However, the of to NEIL1 with the B. J. Biol. PubMed Scopus Google that CSB the activity and This is also and resulting in an in the complex with a the base is formed or the as excision of the these results suggest that CSB stimulates to or cleavage of DNA lesions by NEIL1 of stimulating The and the of CSB NEIL1 has been to with in and in T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google Scholar). is to and to be in The between CSB and has been to the of specifically to CSB has been to be in oxidative stress, and the most of in has been to be the T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google a role for this of CSB in The activity of CSB has been to be for role in the of cells from UV RNA and M. R. J. Bohr V.A. 2002; PubMed Scopus Google Scholar, S. J. A. M. M. E. Bohr V.A. Res. 2002; PubMed Scopus Google Scholar). the or the the are in the of NEIL1 incision activity CSB and and and the of full-length CSB and with NEIL1 with or CSBfl, or NEIL1 incision activity by and in a of CSB to NEIL1 to and in the not NEIL1 incision activity to The of NEIL1 or and B and the of CSB stimulates NEIL1 incision activity to the as CSBfl, the does not NEIL1 incision and mitochondrial from CSB-deficient cells have been to incision activity with from cells with wild type from the cells the in the the are to the incision M. T. C. Bohr V.A. Res. 2003; PubMed Scopus Google Scholar, M. R. J. Bohr V.A. 2002; PubMed Scopus Google Scholar, S. J. A. M. M. E. Bohr V.A. Res. 2002; PubMed Scopus Google Scholar, T. S. de Souza-Pinto N.C. van T. Bohr V.A. 2002; PubMed Scopus (87) Google that the activity is not for the of CSB in the of mutations in the CSB and on of NEIL1 incision The the repair of 8-OH-Gua, that CSB is for the role of CSB in the processing of lesions J. M. C. H. Dizdaroglu M. Bohr V.A. J. Biol. 2001; PubMed Scopus Google Scholar). These proteins from and is in The the of as the protein on NEIL1 incision activity This is with the with the the In addition, the the incision activity of NEIL1 to the as the protein CSB in with results presented a between CSB and NEIL1 during repair of oxidatively induced DNA CSB and NEIL1 are in the complex in by and of CSB and NEIL1 in HeLa cells. The results of endogenous CSB and NEIL1 by This by to NEIL1 that not CSB or NEIL1 and the that this by the and HeLa in the of I. In addition, of HeLa cells of CSB and NEIL1 in the and NEIL1 in mitochondrial as J. de Souza-Pinto N.C. K. Dizdaroglu M. Bohr V.A. J. Biol. 2005; PubMed Scopus Google Scholar). of FapyGua in Cells of NEIL1 and role of NEIL1 and CSB in repair of in also in cells depleted of NEIL1 and CSB by of CSB and NEIL1 by and knockdown, and cells with to levels of DNA from cells with or a and FapyGua levels Cells with a a in the level of FapyGua with in these cells induced FapyGua repaired a of In cells NEIL1 or CSB and NEIL1 to repair FapyGua during a These results that repair of induced FapyGua NEIL1 in HeLa cells. However, in this system of NEIL1 a as of This may of repair of induced in the of It has been proposed that the symptoms of CS may levels of oxidative damage in and and that CSB may play a role in the repair of oxidative DNA These are with the that CSB-deficient cells are hypersensitive to oxidative H. de J. van B. A. Poulsen H.E. van Hoeijmakers J.H. van Mol. Cell. Biol. 2004; PubMed Scopus (87) Google oxidatively induced DNA and are (for review, see Ref. T. M. M.D. Bohr V.A. PubMed Scopus Google Scholar). However, the role of CSB in molecular CS remains A role for CSB in by RNA polymerase II N. S. H. R. J. PubMed Scopus Google may of the neurodegenerative of the it does not explain the accumulation of oxidatively induced DNA lesions and show that endogenous FapyGua and FapyAde in DNA from brain and kidney and that FapyAde in and mtDNA of csb-/- mice The role of CSB in the repair of these lesions by the that of repair of FapyGua in HeLa cells As M. E. van S. A. B. 2002; PubMed Scopus Google the level of is also higher in brain and kidney DNA of csb-/- mice than in mice J. C. M. Bohr V.A. DNA 2002; PubMed Scopus (87) Google Scholar). These results that CSB protein is in the repair of these lesions and suggest that elevated levels of FapyGua and FapyAde may play a role in the of CS. The accumulation of these lesions in the of the csb-/- mice specifically may a role in the neurodegeneration in CS patients. FapyGua and FapyAde are substrates for and NEIL1 M. Dizdaroglu M. Biochemistry. 2004; PubMed Scopus (76) Google Scholar, Dizdaroglu M. J. Biol. 2007; PubMed Scopus Google Scholar, T. I. B. Dizdaroglu M. S. S. A. 2002; PubMed Scopus Google Scholar). the results presented here a and between CSB and NEIL1 in and in and CSB of NEIL1 incision higher and of HeLa cells show that CSB and NEIL1 co-localize in the NEIL1 also in the to mitochondria J. de Souza-Pinto N.C. K. Dizdaroglu M. Bohr V.A. J. Biol. 2005; PubMed Scopus Google Scholar). CSB not co-localize with NEIL1 in the the used the that FapyAde in mtDNA in csb-/- mice may suggest that a may in mitochondria as studies suggest that CSB in cells to and that this of CSB T. D. Bohr V.A. Res. 2007; 35: PubMed Scopus Google Scholar). CSB may be to oxidatively induced DNA the is The role of may be for FapyAde than FapyGua and does not repair FapyAde C. Dizdaroglu M. S. Res. 27: PubMed Scopus Google and NEIL1 is the to repair FapyAde in cells. CSB may NEIL1 incision in a lesion-specific the in with FapyGua, FapyAde, and not in with However, is a for NEIL1, the DNA CSB does not NEIL1 incision in a and CSB does not incision of by These results the in the between CSB and the during DNA that CSB stimulates cleavage by NEIL1 also that base release by NEIL1 is not from cleavage in the or of CSB these not of and of DNA the results suggest that CSB the of the between CSB and NEIL1 used CSB protein and CSB proteins and show that the stimulates NEIL1 incision activity to the as protein and that is the the CSB and proteins the incision activity of NEIL1 to the that the activity of CSB is not required for on NEIL1 A between the of CSB and is also by results that CSB interacts with through the and that the for is the T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google Scholar). the between the of not the and CSB in these are the results a of a protein by a of The of CSB in and could be to be by one or that the activity is for the role of CSB in repair of UV lesions and transcription M. R. J. Bohr V.A. 2002; PubMed Scopus Google Scholar, S. J. A. M. M. E. Bohr V.A. Res. 2002; PubMed Scopus Google not for role in J. M. C. H. Dizdaroglu M. Bohr V.A. J. Biol. 2001; PubMed Scopus Google Scholar, J. H. Dizdaroglu M. Bohr V.A. J. Biol. 2002; PubMed Scopus Google Scholar). with the results presented here that the is also for CSB of NEIL1 these suggest that CSB in the repair is or is not by the The of CSB is increased oxidative stress, and the that this results in a of activity that the activity of CSB is not in the T. M. T. Bohr V.A. Mol. Cell. Biol. 2005; PubMed Scopus Google Scholar). In this study a between CSB and NEIL1 and that the CSB is in complex with NEIL1 in This is to play an role in repair of endogenous and induced in studies show that mice NEIL1 have a complex phenotype the syndrome in The results presented here are with the that higher than normal levels of FapyAde and FapyGua may have and that or FapyAde and FapyGua may to the of CS. and for the of this of for the NEIL1 for for and the for the of the csb-/- with