Journal Article

CDCA7 and HELLS mutations undermine nonhomologous end joining in centromeric instability syndrome

Funabiki, Hironori, Francastel, Claire, Velasco, Guillaume, Sasaki, Hiroyuki, Unoki, Motoko

2019

Overview

Mutations in CDCA7 and HELLS that respectively encode a CXXC-type zinc finger protein and an SNF2 family chromatin remodeler cause immunodeficiency, centromeric instability, and facial anomalies (ICF) syndrome types 3 and 4. Here, we demonstrate that the classical nonhomologous end joining (C-NHEJ) proteins Ku80 and Ku70, as well as HELLS, coimmunoprecipitated with CDCA7. The coimmunoprecipitation of the repair proteins was sensitive to nuclease treatment and an ICF3 mutation in CDCA7 that impairs its chromatin binding. The functional importance of these interactions was strongly suggested by the compromised C-NHEJ activity and significant delay in Ku80 accumulation at DNA damage sites in CDCA7- and HELLS-deficient HEK293 cells. Consistent with the repair defect, these cells displayed increased apoptosis, abnormal chromosome segregation, aneuploidy, centrosome amplification, and significant accumulation of γH2AX signals. Although less prominent, cells with mutations in the other ICF genes DNMT3B and ZBTB24 (responsible for ICF types 1 and 2, respectively) showed similar defects. Importantly, lymphoblastoid cells from ICF patients shared the same changes detected in the mutant HEK293 cells to varying degrees. Although the C-NHEJ defect alone did not cause CG hypomethylation, CDCA7 and HELLS are involved in maintaining CG methylation at centromeric and pericentromeric repeats. The defect in C-NHEJ may account for some common features of ICF cells, including centromeric instability, abnormal chromosome segregation, and apoptosis.

• Publisher: American Society for Clinical Investigation
• Subject: Aneuploidy / Apoptosis / Apoptosis - genetics / Biomedical research / Cancer / Care and treatment / Cell cycle / Cell division / Centromere - genetics / Centromere - metabolism / Centromere - pathology / Chromatin / Chromosome Segregation - genetics / Chromosomes / CpG Islands / Defects / Deoxyribonucleic acid / DNA / DNA Damage / DNA End-Joining Repair / DNA Helicases - genetics / DNA Helicases - metabolism / DNA Methylation / DNA repair / Face - abnormalities / Face - pathology / Female / Gene mutation / Genes / Genetic disorders / HEK293 Cells / Humans / Immunodeficiency / Immunologic Deficiency Syndromes - genetics / Immunologic Deficiency Syndromes - metabolism / Immunologic Deficiency Syndromes - pathology / Ku Autoantigen - genetics / Ku Autoantigen - metabolism / Life Sciences / Male / Mutation / Non-homologous end joining / Nuclear Proteins - genetics / Nuclear Proteins - metabolism / Nuclease / Peptides / Primary Immunodeficiency Diseases / Proteins / Zinc finger proteins