Role of Gab1 in UV-induced c-Jun NH2-terminal kinase activation and cell apoptosis.
Exposure of mammalian cells to UV irradiation leads to activation of the c-Jun NH(2)-terminal protein kinase (JNK) pathway, which is associated with cell apoptosis. However, the molecular mechanism for JNK activation by UV exposure is not fully understood. We show here an essential role of a multisubstrate adapter, Gab1, in this signaling cascade. Gab1-deficient mouse fibroblast cells were defective in induction of JNK activity by UV exposure or heat shock, and this defect was rescued by reintroduction of Gab1 into Gab1(-/-) cells. Consistently, Gab1(-/-) cells displayed reduced caspase 3 induction and apoptotic cell death in response to UV irradiation. Gab1 was constitutively complexed with JNK and became tyrosine phosphorylated in UV-irradiated cells. Genetic and pharmaceutical analyses suggest the involvement of c-Met and the Src family tyrosine kinases in mediating UV-induced Gab1 phosphorylation as well as JNK activation. In aggregate, these observations identify a new function of Gab1 in the response of mammalian cells to UV light.
Sun
Yingqing
Y
Cancer Research Center, The Burnham Institute, La Jolla, California 92037, USA.
Yuan
Jing
J
Liu
Houqi
H
Shi
Zhongqing
Z
Baker
Kelly
K
Vuori
Kristiina
K
Wu
Jie
J
Feng
Gen-Sheng
GS
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis / Q000528:radiation effects*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D004789:Enzyme Activation / Q000528:radiation effects; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005347:Fibroblasts; D017353:Gene Deletion; D018869:Heat-Shock Response; D048031:JNK Mitogen-Activated Protein Kinases; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000528:radiation effects; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding; D014466:Ultraviolet Rays
D048868:Adaptor Proteins, Signal Transducing; C490897:Gab1 protein, mouse; D010750:Phosphoproteins; D019000:Phosphotyrosine; D004815:Epidermal Growth Factor; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases