title: Distinct versus overlapping functions of MDC1 and 53BP1 in DNA damage response and tumorigenesis.
abstract: The importance of the DNA damage response (DDR) pathway in development, genomic stability, and tumor suppression is well recognized. Although 53BP1 and MDC1 have been recently identified as critical upstream mediators in the cellular response to DNA double-strand breaks, their relative hierarchy in the ataxia telangiectasia mutated (ATM) signaling cascade remains controversial. To investigate the divergent and potentially overlapping functions of MDC1 and 53BP1 in the ATM response pathway, we generated mice deficient for both genes. Unexpectedly, the loss of both MDC1 and 53BP1 neither significantly increases the severity of defects in DDR nor increases tumor incidence compared with the loss of MDC1 alone. We additionally show that MDC1 regulates 53BP1 foci formation and phosphorylation in response to DNA damage. These results suggest that MDC1 functions as an upstream regulator of 53BP1 in the DDR pathway and in tumor suppression.
authors.affiliation: Division of Oncology Research, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Katherine
authors.initials: K
authors.lastname: Minter-Dykhouse
authors.forename: Irene
authors.initials: I
authors.lastname: Ward
authors.forename: Michael S Y
authors.initials: MS
authors.lastname: Huen
authors.forename: Junjie
authors.initials: J
authors.lastname: Chen
authors.forename: Zhenkun
authors.initials: Z
authors.lastname: Lou
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone; D004249:DNA Damage; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D047908:Intracellular Signaling Peptides and Proteins / Q000502:physiology*; D008297:Male; D008677:Metaphase; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C508937:MDC1 protein, mouse; C498302:Trp53bp1 protein, mouse; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases