Mechanism of Activation of the RAF-ERK Signaling Pathway by Oncogenic Mutations of B-RAF

Over 30 mutations of the B-RAF gene associated with human cancers have been identified, the majority of which are located within the kinase domain. Here we show that of 22 B-RAF mutants analyzed, 18 have elevated kinase activity and signal to ERK in vivo. Surprisingly, three mutants have reduced kin...

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Bibliographic Details
Published in:Cell 2004-03, Vol.116 (6), p.855-867
Main Authors: Wan, Paul T.C, Garnett, Mathew J, Roe, S.Mark, Lee, Sharlene, Niculescu-Duvaz, Dan, Good, Valerie M, Project, Cancer Genome, Jones, C.Michael, Marshall, Christopher J, Springer, Caroline J, Barford, David, Marais, Richard
Format: Article
Language:English
Subjects:
Allosteric Regulation - genetics
Animals
Catalytic Domain - genetics
Cell Transformation, Neoplastic - genetics
Enzyme Inhibitors - pharmacology
Gene Expression Regulation, Enzymologic - genetics
MAP Kinase Kinase 1
MAP Kinase Signaling System - genetics
Mice
Mitogen-Activated Protein Kinase Kinases - genetics
Mitogen-Activated Protein Kinase Kinases - metabolism
Mitogen-Activated Protein Kinases - genetics
Models, Molecular
Molecular Conformation
Mutation - genetics
Neoplasms - enzymology
Neoplasms - genetics
NIH 3T3 Cells
Oncogenes - genetics
Oocytes
Phosphorylation
Phosphotransferases - genetics
Phosphotransferases - metabolism
Proto-Oncogene Proteins B-raf
Proto-Oncogene Proteins c-raf - antagonists & inhibitors
Proto-Oncogene Proteins c-raf - genetics
Proto-Oncogene Proteins c-raf - metabolism
Up-Regulation - genetics
Xenopus
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Summary:Over 30 mutations of the B-RAF gene associated with human cancers have been identified, the majority of which are located within the kinase domain. Here we show that of 22 B-RAF mutants analyzed, 18 have elevated kinase activity and signal to ERK in vivo. Surprisingly, three mutants have reduced kinase activity towards MEK in vitro but, by activating C-RAF in vivo, signal to ERK in cells. The structures of wild type and oncogenic V599EB-RAF kinase domains in complex with the RAF inhibitor BAY43-9006 show that the activation segment is held in an inactive conformation by association with the P loop. The clustering of most mutations to these two regions suggests that disruption of this interaction converts B-RAF into its active conformation. The high activity mutants signal to ERK by directly phosphorylating MEK, whereas the impaired activity mutants stimulate MEK by activating endogenous C-RAF, possibly via an allosteric or transphosphorylation mechanism.
ISSN:0092-8674
1097-4172
DOI:10.1016/S0092-8674(04)00215-6