title: Autophosphorylation of DNA-dependent protein kinase regulates DNA end processing and may also alter double-strand break repair pathway choice.
abstract: Two highly conserved double-strand break (DSB) repair pathways, homologous recombination (HR) and nonhomologous end joining (NHEJ), function in all eukaryotes. How a cell chooses which pathway to utilize is an area of active research and debate. During NHEJ, the DNA-dependent protein kinase (DNA-PK) functions as a "gatekeeper" regulating DNA end access. Here, we provide evidence that DNA-PK regulates DNA end access via its own autophosphorylation. We demonstrated previously that autophosphorylation within a major cluster of sites likely mediates a conformational change that is critical for DNA end processing. Furthermore, blocking autophosphorylation at these sites inhibits a cell's ability to utilize the other major double-strand break repair pathway, HR. Here, we define a second major cluster of DNA-PK catalytic subunit autophosphorylation sites. Whereas blocking phosphorylation at the first cluster inhibits both end processing and HR, blocking phosphorylation at the second cluster enhances both. We conclude that separate DNA-PK autophosphorylation events may function reciprocally by not only regulating DNA end processing but also affecting DSB repair pathway choice.
authors.affiliation: College of Veterinary Medicine and Department of Pathobiology and Diagnostic Investigation, Michigan State University, East Lansing, 48824, USA.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Cui
authors.forename: Yaping
authors.initials: Y
authors.lastname: Yu
authors.forename: Shikha
authors.initials: S
authors.lastname: Gupta
authors.forename: Young-Moon
authors.initials: YM
authors.lastname: Cho
authors.forename: Susan P
authors.initials: SP
authors.lastname: Lees-Miller
authors.forename: Katheryn
authors.initials: K
authors.lastname: Meek
mesh_terms: D000409:Alanine / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D004247:DNA / Q000235:genetics / Q000378:metabolism*; D004249:DNA Damage; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase / Q000235:genetics / Q000378:metabolism*; D006657:Histones / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010766:Phosphorylation; D011836:Radiation Tolerance / Q000235:genetics; D011995:Recombination, Genetic
chemical_list: D006657:Histones; D004247:DNA; D051747:DNA-Activated Protein Kinase; D000409:Alanine