title: BRCA1 recruitment to damaged DNA sites is dependent on CDK9.
abstract: Double strand break lesions, the most toxic type of DNA damage, are repaired primarily through 2 distinct pathways: homology-directed recombination (HR) and non-homologous end-joining (NHEJ). BRCA1 and 53BP1, 2 proteins containing the BRCT modular domain, play an important role in DNA damage response (DDR) by orchestrating the decision between HR and NHEJ, but the precise mechanisms regarding both pathways are not entirely understood. Previously, our group identified a putative interaction between BRCA1 and BARD1 (BRCA1-associated RING domain 1) and the cyclin-dependent kinase (CDK9). CDK9 is a component of the positive transcription elongation complex and has been implicated in genome integrity maintenance associated with the replication stress response. Here we show that CDK9 interacts with endogenous BRCA1 and BARD1 mediated by their RING finger and BRCT domains, and describe CDK9 ionizing radiation-induced foci (IRIF) formation and its co-localization with BRCA1 in DNA damage sites. Cells lacking CDK9 are characterized by an altered γ-H2AX foci dynamics after DNA damage, a reduced efficiency in HR but not in NHEJ repair, failure to form BRCA1 and RAD51 IRIF and increased sensitivity to genotoxic agents. These data indicate that CDK9 is a player in the DDR and is consistent with its participation in HR pathway by modulating BRCA1 response.
authors.affiliation: a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.
authors.forename: Thales C
authors.initials: TC
authors.lastname: Nepomuceno
authors.affiliation: a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.
authors.forename: Vanessa C
authors.initials: VC
authors.lastname: Fernandes
authors.affiliation: b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil.
authors.forename: Thiago T
authors.initials: TT
authors.lastname: Gomes
authors.affiliation: c Faculdade de Farmácia - Universidade Federal do Rio de Janeiro , Rio de Janeiro , RJ , Brazil.
authors.forename: Renato S
authors.initials: RS
authors.lastname: Carvalho
authors.affiliation: a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.
authors.forename: Guilherme
authors.initials: G
authors.lastname: Suarez-Kurtz
authors.affiliation: d Cancer Epidemiology Program , H. Lee Moffitt Cancer Center & Research Institute , Tampa , FL , USA.
authors.forename: Alvaro N
authors.initials: AN
authors.lastname: Monteiro
authors.affiliation: a Programa de Pesquisa Clínica , Instituto Nacional de Câncer , Rio de Janeiro , Brazil.|b Instituto Federal do Rio de Janeiro - IFRJ , Rio de Janeiro , Brazil.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Carvalho
mesh_terms: D019313:BRCA1 Protein / Q000378:metabolism*; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism*; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects; D004249:DNA Damage; D057809:HEK293 Cells; D006367:HeLa Cells; D006801:Humans; D061986:MCF-7 Cells; D009153:Mutagens / Q000633:toxicity; D011485:Protein Binding / Q000528:radiation effects; D034741:RNA, Small Interfering / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D011839:Radiation, Ionizing; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1 / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
chemical_list: D019313:BRCA1 Protein; D009153:Mutagens; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; C102449:BARD1 protein, human; D044767:Ubiquitin-Protein Ligases; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D051135:Rad51 Recombinase
keywords: BRCA1; CDK9; DNA damage repair; homologous recombination