Ataxia telangiectasia mutant protein activates c-Abl tyrosine kinase in response to ionizing radiation.

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.
Mesh Terms:
3T3 Cells, Animals, Ataxia Telangiectasia, Ataxia Telangiectasia Mutated Proteins, Cell Cycle, Cell Cycle Proteins, Cell Line, Transformed, DNA-Binding Proteins, Enzyme Activation, Gamma Rays, Humans, Mice, Protein-Serine-Threonine Kinases, Proteins, Proto-Oncogene Proteins c-abl, RNA Polymerase II, Transfection, Tumor Suppressor Proteins
Nature
Date: May. 29, 1997
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