title: ATM-dependent MiR-335 targets CtIP and modulates the DNA damage response.
abstract: ATM plays a critical role in cellular responses to DNA double-strand breaks (DSBs). We describe a new ATM-mediated DSB-induced DNA damage response pathway involving microRNA (miRNA): irradiation (IR)-induced DSBs activate ATM, which leads to the downregulation of miR-335, a miRNA that targets CtIP, which is an important trigger of DNA end resection in homologous recombination repair (HRR). We demonstrate that CREB is responsible for a large portion of miR-335 expression by binding to the promoter region of miR-335. CREB binding is greatly reduced after IR, corroborating with previous studies that IR-activated ATM phosphorylates CREB to reduce its transcription activity. Overexpression of miR-335 in HeLa cells resulted in reduced CtIP levels and post-IR colony survival and BRCA1 foci formation. Further, in two patient-derived lymphoblastoid cell lines with decreased post-IR colony survival, a "radiosensitive" phenotype, we demonstrated elevated miR-335 expression, reduced CtIP levels, and reduced BRCA1 foci formation. Colony survival, BRCA1 foci, and CtIP levels were partially rescued by miRNA antisense AMO-miR-335 treatment. Taken together, these findings strongly suggest that an ATM-dependent CREB-miR-335-CtIP axis influences the selection of HRR for repair of certain DSB lesions.
authors.affiliation: Department of Pathology and Laboratory Medicine, University of California Los Angeles, Los Angeles, CA, USA.
authors.forename: Nathan T
authors.initials: NT
authors.lastname: Martin
authors.forename: Kotoka
authors.initials: K
authors.lastname: Nakamura
authors.forename: Robert
authors.initials: R
authors.lastname: Davies
authors.forename: Shareef A
authors.initials: SA
authors.lastname: Nahas
authors.forename: Christina
authors.initials: C
authors.lastname: Brown
authors.forename: Rashmi
authors.initials: R
authors.lastname: Tunuguntla
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gatti
authors.forename: Hailiang
authors.initials: H
authors.lastname: Hu
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D019313:BRCA1 Protein / Q000235:genetics; D002352:Carrier Proteins / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics* / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded / Q000187:drug effects; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair / Q000528:radiation effects; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation / Q000528:radiation effects; D004706:Endodeoxyribonucleases; D015870:Gene Expression / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D035683:MicroRNAs / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D059767:Recombinational DNA Repair / Q000235:genetics* / Q000528:radiation effects; D025521:Tumor Suppressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C556347:MIRN335 microRNA, human; D035683:MicroRNAs; D009687:Nuclear Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases; D004706:Endodeoxyribonucleases; C410741:RBBP8 protein, human