title: RB localizes to DNA double-strand breaks and promotes DNA end resection and homologous recombination through the recruitment of BRG1.
abstract: The retinoblastoma (RB) tumor suppressor is recognized as a master regulator that controls entry into the S phase of the cell cycle. Its loss leads to uncontrolled cell proliferation and is a hallmark of cancer. RB works by binding to members of the E2F family of transcription factors and recruiting chromatin modifiers to the promoters of E2F target genes. Here we show that RB also localizes to DNA double-strand breaks (DSBs) dependent on E2F1 and ATM kinase activity and promotes DSB repair through homologous recombination (HR), and its loss results in genome instability. RB is necessary for the recruitment of the BRG1 ATPase to DSBs, which stimulates DNA end resection and HR. A knock-in mutation of the ATM phosphorylation site on E2F1 (S29A) prevents the interaction between E2F1 and TopBP1 and recruitment of RB, E2F1, and BRG1 to DSBs. This knock-in mutation also impairs DNA repair, increases genomic instability, and renders mice hypersensitive to IR. Importantly, depletion of RB in osteosarcoma and breast cancer cell lines results in sensitivity to DNA-damaging drugs, which is further exacerbated by poly-ADP ribose polymerase (PARP) inhibitors. We uncovered a novel, nontranscriptional function for RB in HR, which could contribute to genome instability associated with RB loss.
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.
authors.forename: Renier
authors.identifier: 0000-0003-1857-4312
authors.initials: R
authors.lastname: Vélez-Cruz
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.
authors.forename: Swarnalatha
authors.initials: S
authors.lastname: Manickavinayaham
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.
authors.forename: Anup K
authors.initials: AK
authors.lastname: Biswas
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.|The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77225, USA.
authors.forename: Regina Weaks
authors.initials: RW
authors.lastname: Clary
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.|The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77225, USA.
authors.forename: Tolkappiyan
authors.initials: T
authors.lastname: Premkumar
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.|The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77225, USA.
authors.forename: Francesca
authors.initials: F
authors.lastname: Cole
authors.affiliation: Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville Texas 78957, USA.|The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77225, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Johnson
mesh_terms: D000818:Animals; D002460:Cell Line; D045744:Cell Line, Tumor; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects / Q000528:radiation effects; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair / Q000235:genetics; D050687:E2F1 Transcription Factor / Q000235:genetics / Q000378:metabolism; D005720:Gamma Rays; D055879:Gene Knock-In Techniques; D042822:Genomic Instability / Q000235:genetics; D059765:Homologous Recombination / Q000235:genetics*; D006801:Humans; D008297:Male; D051379:Mice; D009153:Mutagens / Q000494:pharmacology; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D000067856:Poly(ADP-ribose) Polymerase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000235:genetics; D016160:Retinoblastoma Protein / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014916:Whole-Body Irradiation / Q000401:mortality
chemical_list: D050687:E2F1 Transcription Factor; C493754:E2f1 protein, mouse; D009153:Mutagens; D009687:Nuclear Proteins; D000067856:Poly(ADP-ribose) Polymerase Inhibitors; D016160:Retinoblastoma Protein; D014157:Transcription Factors; C513194:Smarca4 protein, mouse; D004265:DNA Helicases
keywords: BRG1; DNA end resection; E2F1; SWI/SNF; homologous recombination; retinoblastoma