title: MCPH1 functions in an H2AX-dependent but MDC1-independent pathway in response to DNA damage.
abstract: Microcephalin (MCPH1) is one of the causative genes for the autosomal recessive disorder, primary microcephaly, characterized by dramatic reduction in brain size and mental retardation. MCPH1 also functions in the DNA damage response, participating in cell cycle checkpoint control. However, how MCPH1 is regulated in the DNA damage response still remains unknown. Here we report that the ability of MCPH1 to localize to the sites of DNA double-strand breaks depends on its C-terminal tandem BRCT domains. Although MCPH1 foci formation depends on H2AX phosphorylation after DNA damage, it can occur independently of MDC1. We also show that MCPH1 binds to a phospho-H2AX peptide in vitro with an affinity similar to that of MDC1, and overexpression of wild type, but not C-BRCT mutants of MCPH1, can interfere with the foci formation of MDC1 and 53BP1. Collectively, our data suggest MCPH1 is recruited to double-strand breaks via its interaction with gammaH2AX, which is mediated by MCPH1 C-terminal BRCT domains. These observations support that MCPH1 acts early in DNA damage responsive pathways.
authors.affiliation: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Jamie L
authors.initials: JL
authors.lastname: Wood
authors.forename: Namit
authors.initials: N
authors.lastname: Singh
authors.forename: Georges
authors.initials: G
authors.lastname: Mer
authors.forename: Junjie
authors.initials: J
authors.lastname: Chen
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002469:Cell Separation; D003598:Cytoskeletal Proteins; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D005434:Flow Cytometry; D006367:HeLa Cells; D006657:Histones / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000378:metabolism / Q000502:physiology*; D009687:Nuclear Proteins / Q000378:metabolism*; D010766:Phosphorylation; D015534:Trans-Activators / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D003598:Cytoskeletal Proteins; D004268:DNA-Binding Proteins; C468783:H2AX protein, human; D006657:Histones; C460645:MCPH1 protein, human; C413163:MDC1 protein, human; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators