Abstract
Mre11 complex promotes repair of DNA double-strand breaks (DSBs). Xenopus Mre11 (X-Mre11) has been cloned, and its role in DNA replication and DNA damage checkpoint studied in cell-free extracts. DSBs stimulate the phosphorylation and 3'-5' exonuclease activity of X-Mre11 complex. This induced phosphorylation is ATM independent. Phosphorylated X-Mre11 is found associated with replicating nuclei. X-Mre11 complex is required to yield normal DNA replication products. Genomic DNA replicated in extracts immunodepleted of X-Mre11 complex accumulates DSBs as demonstrated by TUNEL assay and reactivity to phosphorylated histone H2AX antibodies. In contrast, the ATM-dependent DNA damage checkpoint that blocks DNA replication initiation is X-Mre11 independent. These results strongly suggest that the function of X-Mre11 complex is to repair DSBs that arise during normal DNA replication, thus unraveling a critical link between recombination-dependent repair and DNA replication.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Antifungal Agents / pharmacology
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Caffeine / pharmacology
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Cell Cycle / physiology*
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Cell Nucleus / metabolism
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Cell-Free System
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Chromatin / metabolism
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DNA Damage*
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DNA Repair*
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DNA Replication*
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / metabolism*
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Humans
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Immunoblotting
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In Situ Nick-End Labeling
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MRE11 Homologue Protein
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Models, Biological
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Molecular Sequence Data
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Oocytes / chemistry
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Oocytes / physiology
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Phosphodiesterase Inhibitors / pharmacology
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Phosphoprotein Phosphatases / antagonists & inhibitors
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Phosphorylation
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Protein Binding
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Pyrans*
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Spiro Compounds*
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Xenopus laevis / genetics
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Xenopus laevis / physiology
Substances
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Antifungal Agents
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Chromatin
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DNA-Binding Proteins
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MRE11 protein, human
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Phosphodiesterase Inhibitors
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Pyrans
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Recombinant Proteins
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Spiro Compounds
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tautomycin
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Caffeine
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MRE11 Homologue Protein
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Phosphoprotein Phosphatases