title: DNA-PKcs and ATM influence generation of ionizing radiation-induced bystander signals.
abstract: The phenomenon by which irradiated cells influence non-irradiated neighboring cells, referred to as the bystander effect (BSE), is not well understood in terms of the underlying pathways involved. We sought to enlighten connections between DNA damage repair and the BSE. Utilizing sister chromatid exchange (SCE) frequencies as a marker of the BSE, we performed cell transfer strategies that enabled us to distinguish between generation versus reception of a bystander signal. We find that DNA-dependent Protein Kinase catalytic subunit (DNA-PKcs) and Ataxia Telangectasia Mutated (ATM) are necessary for the generation of such a bystander signal in normal human cells following gamma (gamma)-ray exposure, but are not required for its reception. Importantly, we also show that directly irradiated human cells do not respond to receipt of a bystander signal, helping to explain why the BSE is a low-dose phenomenon. These studies provide the first evidence for a role of the DNA damage response proteins DNA-PKcs and ATM specifically in the generation of a bystander signal and intercellular signaling.
authors.affiliation: Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523-1618, USA.
authors.forename: R T
authors.initials: RT
authors.lastname: Hagelstrom
authors.forename: K F
authors.initials: KF
authors.lastname: Askin
authors.forename: A J
authors.initials: AJ
authors.lastname: Williams
authors.forename: L
authors.initials: L
authors.lastname: Ramaiah
authors.forename: C
authors.initials: C
authors.lastname: Desaintes
authors.forename: E H
authors.initials: EH
authors.lastname: Goodwin
authors.forename: R L
authors.initials: RL
authors.lastname: Ullrich
authors.forename: S M
authors.initials: SM
authors.lastname: Bailey
mesh_terms: D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D024201:Bystander Effect / Q000528:radiation effects*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002478:Cells, Cultured; D004249:DNA Damage / Q000528:radiation effects*; D004260:DNA Repair / Q000528:radiation effects*; D051747:DNA-Activated Protein Kinase / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D005720:Gamma Rays; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D015398:Signal Transduction / Q000528:radiation effects; D025521:Tumor Suppressor Proteins / Q000378:metabolism*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases