title: Tumor suppressor and deubiquitinase BAP1 promotes DNA double-strand break repair.
abstract: The cellular response to highly genotoxic DNA double-strand breaks (DSBs) involves the exquisite coordination of multiple signaling and repair factors. Here, we conducted a functional RNAi screen and identified BAP1 as a deubiquitinase required for efficient assembly of the homologous recombination (HR) factors BRCA1 and RAD51 at ionizing radiation (IR) -induced foci. BAP1 is a chromatin-associated protein frequently inactivated in cancers of various tissues. To further investigate the role of BAP1 in DSB repair, we used a gene targeting approach to knockout (KO) this deubiquitinase in chicken DT40 cells. We show that BAP1-deficient cells are (i) sensitive to IR and other agents that induce DSBs, (ii) defective in HR-mediated immunoglobulin gene conversion, and (iii) exhibit an increased frequency of chromosomal breaks after IR treatment. We also show that BAP1 is recruited to chromatin in the proximity of a single site-specific I-SceI-induced DSB. Finally, we identified six IR-induced phosphorylation sites in BAP1 and showed that mutation of these residues inhibits BAP1 recruitment to DSB sites. We also found that both BAP1 catalytic activity and its phosphorylation are critical for promoting DNA repair and cellular recovery from DNA damage. Our data reveal an important role for BAP1 in DSB repair by HR, thereby providing a possible molecular basis for its tumor suppressor function.
authors.affiliation: Maisonneuve-Rosemont Hospital Research Center, Department of Medicine, Université de Montréal, Montréal, QC, Canada H1T 2M4.
authors.forename: Helen
authors.initials: H
authors.lastname: Yu
authors.forename: Helen
authors.initials: H
authors.lastname: Pak
authors.forename: Ian
authors.initials: I
authors.lastname: Hammond-Martel
authors.forename: Mehdi
authors.initials: M
authors.lastname: Ghram
authors.forename: Amélie
authors.initials: A
authors.lastname: Rodrigue
authors.forename: Salima
authors.initials: S
authors.lastname: Daou
authors.forename: Haithem
authors.initials: H
authors.lastname: Barbour
authors.forename: Luc
authors.initials: L
authors.lastname: Corbeil
authors.forename: Josée
authors.initials: J
authors.lastname: Hébert
authors.forename: Elliot
authors.initials: E
authors.lastname: Drobetsky
authors.forename: Jean Yves
authors.initials: JY
authors.lastname: Masson
authors.forename: Javier M
authors.initials: JM
authors.lastname: Di Noia
authors.forename: El Bachir
authors.initials: el B
authors.lastname: Affar
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002645:Chickens; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004260:DNA Repair; D015972:Gene Expression Regulation, Neoplastic; D057809:HEK293 Cells; D006367:HeLa Cells; D059765:Homologous Recombination; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics; D061986:MCF-7 Cells; D008856:Microscopy, Fluorescence; D009154:Mutation; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010766:Phosphorylation; D051135:Rad51 Recombinase; D011839:Radiation, Ionizing; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*
chemical_list: C400134:BAP1 protein, human; D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D007136:Immunoglobulins; D025521:Tumor Suppressor Proteins; C495153:RAD51 protein, human; D051135:Rad51 Recombinase; D043222:Ubiquitin Thiolesterase