title: Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation.
abstract: Ataxia telangiectasia (AT) is a rare human autosomal recessive disorder with pleiotropic phenotypes, including neuronal degeneration, immune dysfunction, premature ageing and increased cancer risk. The gene mutated in AT, ATM, encodes a putative lipid or protein kinase. Most of the human AT patient phenotypes are recapitulated in Atm-deficient mice. Cells derived from Atm-/- mice, like those from AT patients, exhibit abnormal response to ionizing radiation. One of the known responses to ionizing radiation is the activation of a nuclear tyrosine kinase encoded by the c-abl proto-oncogene. Ionizing radiation does not activate c-Abl in cells from AT patients or in thymocytes or fibroblasts from the Atm-deficient mice. Ectopic expression of a functional ATM kinase domain corrects this defect, as it phosphorylates the c-Abl tyrosine kinase in vitro at Ser 465, leading to the activation of c-Abl. A mutant c-Abl with Ser 465 changed to Ala 465 is not activated by ionizing radiation or ATM kinase in vivo. These findings identify the c-Abl tyrosine kinase as a downstream target of phosphorylation and activation by the ATM kinase in the cellular response to ionizing radiation.
authors.affiliation: Department of Biology and Center for Molecular Genetics, University of California at San Diego, La Jolla 92093-0322, USA.
authors.forename: R
authors.initials: R
authors.lastname: Baskaran
authors.forename: L D
authors.initials: LD
authors.lastname: Wood
authors.forename: L L
authors.initials: LL
authors.lastname: Whitaker
authors.forename: C E
authors.initials: CE
authors.lastname: Canman
authors.forename: S E
authors.initials: SE
authors.lastname: Morgan
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: C
authors.initials: C
authors.lastname: Barlow
authors.forename: D
authors.initials: D
authors.lastname: Baltimore
authors.forename: A
authors.initials: A
authors.lastname: Wynshaw-Boris
authors.forename: M B
authors.initials: MB
authors.lastname: Kastan
authors.forename: J Y
authors.initials: JY
authors.lastname: Wang
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001260:Ataxia Telangiectasia / Q000201:enzymology*; D064007:Ataxia Telangiectasia Mutated Proteins; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D002461:Cell Line, Transformed; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000528:radiation effects; D005720:Gamma Rays; D006801:Humans; D051379:Mice; D017346:Protein Serine-Threonine Kinases; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D000090063:Proto-Oncogene Mas; D016315:Proto-Oncogene Proteins c-abl / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism; D014162:Transfection; D025521:Tumor Suppressor Proteins
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D011506:Proteins; D000090063:Proto-Oncogene Mas; D025521:Tumor Suppressor Proteins; D016315:Proto-Oncogene Proteins c-abl; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D012319:RNA Polymerase II