BRUCE regulates DNA double-strand break response by promoting USP8 deubiquitination of BRIT1.
The DNA damage response (DDR) is crucial for genomic integrity. BRIT1 (breast cancer susceptibility gene C terminus-repeat inhibitor of human telomerase repeat transcriptase expression), a tumor suppressor and early DDR factor, is recruited to DNA double-strand breaks (DSBs) by phosphorylated H2A histone family, member X (γ-H2AX), where it promotes chromatin relaxation by recruiting the switch/sucrose nonfermentable (SWI-SNF) chromatin remodeler to facilitate DDR. However, regulation of BRIT1 recruitment is not fully understood. The baculovirus IAP repeat (BIR)-containing ubiquitin-conjugating enzyme (BRUCE) is an inhibitor of apoptosis protein (IAP). Here, we report a non-IAP function of BRUCE in the regulation of the BRIT1-SWI-SNF DSB-response pathway and genomic stability. We demonstrate that BRIT1 is K63 ubiquitinated in unstimulated cells and that deubiquitination of BRIT1 is a prerequisite for its recruitment to DSB sites by γ-H2AX. We show mechanistically that BRUCE acts as a scaffold, bridging the ubiquitin-specific peptidase 8 (USP8) and BRIT1 in a complex to coordinate USP8-catalyzed deubiquitination of BRIT1. Loss of BRUCE or USP8 impairs BRIT1 deubiquitination, BRIT1 binding with γ-H2AX, the formation of BRIT1 DNA damage foci, and chromatin relaxation. Moreover, BRUCE-depleted cells display reduced homologous recombination repair, and BRUCE-mutant mice exhibit repair defects and genomic instability. These findings identify BRUCE and USP8 as two hitherto uncharacterized critical DDR regulators and uncover a deubiquitination regulation of BRIT1 assembly at damaged chromatin for efficient DDR and genomic stability.
Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267;
Chunmin
C
Ge
Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267;
Lixiao
L
Che
Institute of Hepatology, Second People's Hospital of Lanzhou, Gansu Province 730046, China;
Jinyu
J
Ren
Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030;
Raj K
RK
Pandita
Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267;
Jing
J
Lu
Department of Surgery, Baylor College of Medicine, Houston, TX 77030; and.
Kaiyi
K
Li
Department of Radiation Oncology, The Houston Methodist Research Institute, Houston, TX 77030; Department of Radiation Oncology, Washington University, St Louis, MO 63108.
Tej K
TK
Pandita
Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267; chunying.du@uc.edu.
Chunying
C
Du
D000818:Animals; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D033481:Chromosomes, Mammalian / Q000378:metabolism; D003598:Cytoskeletal Proteins; D053903:DNA Breaks, Double-Stranded; D004260:DNA Repair; D004622:Embryo, Mammalian / Q000166:cytology; D010450:Endopeptidases / Q000378:metabolism*; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism; D042822:Genomic Instability; D057809:HEK293 Cells; D006657:Histones / Q000378:metabolism; D059765:Homologous Recombination / Q000235:genetics; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D051379:Mice; D046912:Multiprotein Complexes / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D025821:Polyubiquitin / Q000378:metabolism; D021381:Protein Transport; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*; D054875:Ubiquitination
C401541:BIRC6 protein, human; C490597:BIRC6 protein, mouse; D018797:Cell Cycle Proteins; D002843:Chromatin; D003598:Cytoskeletal Proteins; D056827:Endosomal Sorting Complexes Required for Transport; C468783:H2AX protein, human; D006657:Histones; D051034:Inhibitor of Apoptosis Proteins; C460645:MCPH1 protein, human; D046912:Multiprotein Complexes; D009419:Nerve Tissue Proteins; D025821:Polyubiquitin; D010450:Endopeptidases; C541534:USP8 protein, human; D043222:Ubiquitin Thiolesterase; D008239:Lysine
BRIT1; BRUCE; DNA DSB repair; inhibitor of apoptosis