title: Alteration/deficiency in activation-3 (Ada3) plays a critical role in maintaining genomic stability.
abstract: Cell cycle regulation and DNA repair following damage are essential for maintaining genome integrity. DNA damage activates checkpoints in order to repair damaged DNA prior to exit to the next phase of cell cycle. Recently, we have shown the role of Ada3, a component of various histone acetyltransferase complexes, in cell cycle regulation, and loss of Ada3 results in mouse embryonic lethality. Here, we used adenovirus-Cre-mediated Ada3 deletion in Ada3(fl/fl) mouse embryonic fibroblasts (MEFs) to assess the role of Ada3 in DNA damage response following exposure to ionizing radiation (IR). We report that Ada3 depletion was associated with increased levels of phospho-ATM (pATM), γH2AX, phospho-53BP1 (p53BP1) and phospho-RAD51 (pRAD51) in untreated cells; however, radiation response was intact in Ada3(-/-) cells. Notably, Ada3(-/-) cells exhibited a significant delay in disappearance of DNA damage foci for several critical proteins involved in the DNA repair process. Significantly, loss of Ada3 led to enhanced chromosomal aberrations, such as chromosome breaks, fragments, deletions and translocations, which further increased upon DNA damage. Notably, the total numbers of aberrations were more clearly observed in S-phase, as compared with G₁ or G₂ phases of cell cycle with IR. Lastly, comparison of DNA damage in Ada3(fl/fl) and Ada3(-/-) cells confirmed higher residual DNA damage in Ada3(-/-) cells, underscoring a critical role of Ada3 in the DNA repair process. Taken together, these findings provide evidence for a novel role for Ada3 in maintenance of the DNA repair process and genomic stability.
authors.affiliation: Department of Genetics, Cell Biology and Anatomy, University of Nebraska Medical Center, Omaha, NE, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Mirza
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: Katafiasz
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Shakur
authors.initials: S
authors.lastname: Mohibi
authors.forename: Smrati
authors.initials: S
authors.lastname: Jain
authors.forename: Channabasavaiah Basavaraju
authors.initials: CB
authors.lastname: Gurumurthy
authors.forename: Tej K
authors.initials: TK
authors.lastname: Pandita
authors.forename: Bhavana J
authors.initials: BJ
authors.lastname: Dave
authors.forename: Hamid
authors.initials: H
authors.lastname: Band
authors.forename: Vimla
authors.initials: V
authors.lastname: Band
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism; D002869:Chromosome Aberrations; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D016193:G1 Phase; D016195:G2 Phase; D042822:Genomic Instability; D006657:Histones / Q000378:metabolism; D007621:Karyotyping; D051379:Mice; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D011839:Radiation, Ionizing; D014157:Transcription Factors / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000071857:Tumor Suppressor p53-Binding Protein 1
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D006657:Histones; D017346:Protein Serine-Threonine Kinases; D051135:Rad51 Recombinase; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D000071857:Tumor Suppressor p53-Binding Protein 1; C501070:RBBP8 protein, mouse; C580756:Tada3 protein, mouse; C498302:Trp53bp1 protein, mouse; C576325:Atm protein, mouse; C495154:Rad51 protein, mouse; C475961:gamma-H2AX protein, mouse