The D816V mutation of c-Kit circumvents a requirement for Src family kinases in c-Kit signal transduction.
The receptor tyrosine kinase c-Kit plays a critical role in hematopoiesis, and gain-of-function mutations of the receptor are frequently seen in several malignancies, including acute myeloid leukemia, gastrointestinal stromal tumors, and testicular carcinoma. The most common mutation of c-Kit in these disorders is a substitution of the aspartic acid residue in position 816 to a valine (D816V), leading to constitutive activation of the receptor. In this study, we aimed to investigate the role of Src family kinases in c-Kit/D816V signaling. Src family kinases are necessary for the phosphorylation of wild-type c-Kit as well as of activation of downstream signaling pathways including receptor ubiquitination and the Ras/Mek/Erk pathway. Our data demonstrate that, unlike wild-type c-Kit, the phosphorylation of c-Kit/D816V is not dependent on Src family kinases. In addition, we found that neither receptor ubiquitination nor Erk activation by c-Kit/D816V required activation of Src family kinases. In vitro kinase assay using synthetic peptides revealed that c-Kit/D816V had an altered substrate specificity resembling Src and Abl tyrosine kinases. We further present evidence that, in contrast to wild-type c-Kit, Src family kinases are dispensable for c-Kit/D816V cell survival, proliferation, and colony formation. Taken together, we demonstrate that the signal transduction pathways mediated by c-Kit/D816V are markedly different from those activated by wild-type c-Kit and that altered substrate specificity of c-Kit circumvents a need for Src family kinases in signaling of growth and survival, thereby contributing to the transforming potential of c-Kit/D816V.
Sun
Jianmin
J
Experimental Clinical Chemistry, the Department of Laboratory Medicine, Lund University, Malmö University Hospital, SE-205 02 Malmö, Sweden.
Pedersen
Malin
M
Rönnstrand
Lars
L
D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D049109:Cell Proliferation; D002470:Cell Survival; D006801:Humans; D051379:Mice; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction; D013379:Substrate Specificity; D025801:Ubiquitin / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
D025801:Ubiquitin; D019009:Proto-Oncogene Proteins c-kit; D019061:src-Family Kinases