title: Novel localization of the DNA-PK complex in lipid rafts: a putative role in the signal transduction pathway of the ionizing radiation response.
abstract: Increased sensitivity to ionizing radiation (IR) has been shown to be due to defects in DNA double-strand break repair machinery. The major pathway in mammalian cells dedicated to the repair of DNA double-strand breaks is by the nonhomologous end-joining machinery. Six components function in this pathway, of which three (Ku70, Ku86, and DNA-PKcs) constitute a protein complex known as DNA-dependent protein kinase (DNA-PK). However, it is now recognized that the cellular radiation response is complex, and radiosensitivity may be also regulated at different levels in the radiation signal transduction pathway. In addition to DNA damage, exposure to IR triggers intracellular signaling cascades that overlap with pathways initiated by ligand engagement to a receptor. In this study, we provide evidence for the novel localization of the DNA-PK complex in lipid rafts. We also show this property is not a generalized characteristic of all DNA repair proteins. Furthermore, we have detected Ku86 in yeast lipid rafts. Our results suggest that the components of this complex might be recruited separately to the plasma membrane by tethering with raft-resident proteins. In addition, we found an irradiation-induced differential protein phosphorylation pattern dependent upon DNA-PKcs in lipid rafts. Thus, we speculate that another role for the DNA-PKcs subunit and perhaps for the holoenzyme is in the signal transduction of IR response.
authors.affiliation: Departments of Molecular and Cellular Biology, Goldman School of Dental Medicine, Boston University, Boston, MA 02118, USA.
authors.forename: Hector
authors.initials: H
authors.lastname: Lucero
authors.forename: Darren
authors.initials: D
authors.lastname: Gae
authors.forename: Guillermo E
authors.initials: GE
authors.lastname: Taccioli
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000378:metabolism; D034961:Antigens, Nuclear / Q000378:metabolism; D015153:Blotting, Western; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002784:Cholesterol / Q000378:metabolism; D006224:Cricetinae; D004265:DNA Helicases; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D000072200:Ku Autoantigen; D021962:Membrane Microdomains / Q000378:metabolism* / Q000528:radiation effects; D008861:Microsomes / Q000378:metabolism; D009687:Nuclear Proteins; D010766:Phosphorylation; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011839:Radiation, Ionizing; D015398:Signal Transduction; D013696:Temperature; D014407:Tumor Cells, Cultured
chemical_list: D000911:Antibodies, Monoclonal; D034961:Antigens, Nuclear; D004268:DNA-Binding Proteins; D009687:Nuclear Proteins; D002784:Cholesterol; D051747:DNA-Activated Protein Kinase; C497263:PRKDC protein, human; D017346:Protein Serine-Threonine Kinases; D004265:DNA Helicases; C106893:XRCC5 protein, human; C000606509:Xrcc6 protein, human; D000072200:Ku Autoantigen