A requirement for polymerized actin in DNA double-strand break repair.
Nuclear actin is involved in several nuclear processes from chromatin remodeling to transcription. Here we examined the requirement for actin polymerization in DNA double-strand break repair. Double-strand breaks are considered the most dangerous type of DNA lesion. Double-strand break repair consists of a complex set of events that are tightly regulated. Failure at any step can have catastrophic consequences such as genomic instability, oncogenesis or cell death. Many proteins involved in this repair process have been identified and their roles characterized. We discovered that some DNA double-strand break repair factors are capable of associating with polymeric actin in vitro and specifically, that purified Ku70/80 interacts with polymerized actin under these conditions. We find that the disruption of polymeric actin inhibits DNA double strand break repair both in vitro and in vivo. Introduction of nuclear targeted mutant actin that cannot polymerize, or the depolymerization of endogenous actin filaments by the addition of cytochalasin D, alters the retention of Ku80 at sites of DNA damage in live cells. Our results suggest that polymeric actin is required for proper DNA double-strand break repair and may function through the stabilization of the Ku heterodimer at the DNA damage site.
Department of Oncology, University of Alberta, Edmonton, AB Canada.
Christi
C
Andrin
Darin
D
McDonald
Kathleen M
KM
Attwood
Amélie
A
Rodrigue
Sunita
S
Ghosh
Razmik
R
Mirzayans
Jean-Yves
JY
Masson
Graham
G
Dellaire
Michael J
MJ
Hendzel
D000199:Actins / Q000737:chemistry / Q000378:metabolism*; D034961:Antigens, Nuclear / Q000378:metabolism; D001665:Binding Sites; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D000072200:Ku Autoantigen; D058105:Polymerization
D000199:Actins; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D049452:Green Fluorescent Proteins; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen