Abstract
LSH, a protein related to the SNF2 family of chromatin-remodelling ATPases, is essential for the correct establishment of DNA methylation levels and patterns in plants and mammalian cells. However, some of the phenotypes resulting from LSH deficiency cannot be explained easily by defects in DNA methylation. Here we show that LSH-deficient mouse and human fibroblasts show reduced viability after exposure to ionizing radiation and repair DNA double-strand breaks less efficiently than wild-type cells. A more detailed characterisation of this phenotype revealed that, in the absence of LSH, the histone variant H2AX is not efficiently phosphorylated in response to DNA damage. This results in impaired recruitment of MDC1 and 53BP1 proteins to DNA double-strand breaks and compromises phosphorylation of checkpoint kinase CHK2. Furthermore, we demonstrate that the ability of LSH to hydrolyse ATP is necessary for efficient phosphorylation of H2AX at DNA double-strand breaks and successful repair of DNA damage. Taken together, our data reveal a previously unsuspected role of LSH ATPase in the maintenance of genome stability in mammalian somatic cells, which is independent of its function in de novo DNA methylation during development.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Adaptor Proteins, Signal Transducing
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Adenosine Triphosphatases / metabolism*
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Animals
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Cell Cycle Proteins
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Checkpoint Kinase 2
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DNA Breaks, Double-Stranded* / radiation effects
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DNA Helicases / deficiency
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DNA Helicases / metabolism*
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DNA Methylation / radiation effects
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DNA Repair* / radiation effects
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Enzyme Activation / radiation effects
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Fibroblasts / metabolism
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Fibroblasts / radiation effects
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Histones / metabolism*
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Humans
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Intracellular Signaling Peptides and Proteins / metabolism
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Kinetics
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Mammals / metabolism
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Mice
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Mutant Proteins / metabolism
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Phosphorylation / radiation effects
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Protein Serine-Threonine Kinases / metabolism
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Radiation, Ionizing
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Saccharomyces cerevisiae Proteins / metabolism*
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Signal Transduction / radiation effects
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Transcription Factors / metabolism*
Substances
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Adaptor Proteins, Signal Transducing
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Cell Cycle Proteins
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H2AX protein, human
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H2AX protein, mouse
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Histones
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Intracellular Signaling Peptides and Proteins
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MDC1 protein, mouse
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Mutant Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Checkpoint Kinase 2
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CHEK2 protein, human
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Chek2 protein, mouse
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Protein Serine-Threonine Kinases
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Adenosine Triphosphatases
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SNF2 protein, S cerevisiae
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DNA Helicases
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HELLS protein, human
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lymphoid specific helicase, mouse