Abstract
FANCJ mutations are linked to Fanconi anemia (FA) and increase breast cancer risk. FANCJ encodes a DNA helicase implicated in homologous recombination (HR) repair of double-strand breaks (DSBs) and interstrand cross-links (ICLs), but its mechanism of action is not well understood. Here we show with live-cell imaging that FANCJ recruitment to laser-induced DSBs but not psoralen-induced ICLs is dependent on nuclease-active MRE11. FANCJ interacts directly with MRE11 and inhibits its exonuclease activity in a specific manner, suggesting that FANCJ regulates the MRE11 nuclease to facilitate DSB processing and appropriate end resection. Cells deficient in FANCJ and MRE11 show increased ionizing radiation (IR) resistance, reduced numbers of γH2AX and RAD51 foci, and elevated numbers of DNA-dependent protein kinase catalytic subunit foci, suggesting that HR is compromised and the nonhomologous end-joining (NHEJ) pathway is elicited to help cells cope with IR-induced strand breaks. Interplay between FANCJ and MRE11 ensures a normal response to IR-induced DSBs, whereas FANCJ involvement in ICL repair is regulated by MLH1 and the FA pathway. Our findings are discussed in light of the current model for HR repair.
Publication types
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Research Support, N.I.H., Intramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Acid Anhydride Hydrolases
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Basic-Leucine Zipper Transcription Factors / genetics
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Basic-Leucine Zipper Transcription Factors / metabolism*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Chromosomal Instability
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DNA Breaks, Double-Stranded
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DNA Damage*
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DNA Repair / physiology*
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DNA Repair / radiation effects
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DNA Repair Enzymes / genetics
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DNA Repair Enzymes / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism*
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Endodeoxyribonucleases
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Fanconi Anemia Complementation Group Proteins / genetics
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Fanconi Anemia Complementation Group Proteins / metabolism*
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Ficusin / pharmacology
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HeLa Cells / drug effects
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HeLa Cells / radiation effects
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Humans
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MRE11 Homologue Protein
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Radiation, Ionizing
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Recombinational DNA Repair
Substances
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BACH1 protein, human
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Basic-Leucine Zipper Transcription Factors
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Carrier Proteins
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DNA-Binding Proteins
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Fanconi Anemia Complementation Group Proteins
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MRE11 protein, human
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Nuclear Proteins
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Endodeoxyribonucleases
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MRE11 Homologue Protein
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RBBP8 protein, human
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Acid Anhydride Hydrolases
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RAD50 protein, human
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DNA Repair Enzymes
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Ficusin