THE SRC FAMILY KINASE HCK INTERACTS WITH BCR-ABL BY A KINASE-INDEPENDENT MECHANISM AND PHOSPHORYLATES THE GRB2-BINDING SITE OF BCR

Citation
M. Warmuth et al., THE SRC FAMILY KINASE HCK INTERACTS WITH BCR-ABL BY A KINASE-INDEPENDENT MECHANISM AND PHOSPHORYLATES THE GRB2-BINDING SITE OF BCR, The Journal of biological chemistry, 272(52), 1997, pp. 33260-33270
Citations number
55
Language
INGLESE
art.tipo
Article
ISSN journal
0021-9258
Volume
272
Issue
52
Year of publication
1997
Pages
33260 - 33270
Database
ISI
SICI code
0021-9258(1997)272:52<33260:TSFKHI>2.0.ZU;2-S
Abstract
bcr-abl, the oncogene causing chronic myeloid leukemia, encodes a fusi on protein with constitutively active tyrosine kinase and transforming capacity in hematopoietic cells. Various intracellular signaling inte rmediates become activated and/or associate by/with Bcr-Abl, including the Src family kinase Hck. To elucidate some of the structural requir ements and functional consequences of the association of Bcr-Abl with Hcb, their interaction was investigated in transiently transfected COS 7 cells. Neither the complex formation of Hck kinase with Bcr-Abl nor the activation of Hck by Bcr-Abl was dependent on the Abl kinase activ ity. Both inactivating point mutations of Hck and dephosphorylation of Hck enhanced its complex formation with Bcr-Abl, indicating that thei r physical interaction was negatively regulated by Hck (auto)phosphory lation. Finally, experiments with a series of kinase negative Bcr-Abl mutants showed that Hck phosphorylated Bcr-Abl and induced the binding of Grb2 to Tyr(177) of Bcr-Abl. Taken together, our results suggest t hat Bcr-Abl preferentially binds inactive forms of Hck by an Abl kinas e-independent mechanism. This physical interaction stimulates the Hck tyrosine kinase, which may then phosphorylate the Grb2-binding site in Bcr-Abl.