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

Cell. 2004 Mar 19;116(6):855-67. doi: 10.1016/s0092-8674(04)00215-6.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 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*
  • NIH 3T3 Cells
  • Neoplasms / enzymology
  • Neoplasms / genetics
  • 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

Substances

  • Enzyme Inhibitors
  • Phosphotransferases
  • Braf protein, mouse
  • Proto-Oncogene Proteins B-raf
  • Proto-Oncogene Proteins c-raf
  • Mitogen-Activated Protein Kinases
  • MAP Kinase Kinase 1
  • MAP2K1 protein, human
  • Map2k1 protein, mouse
  • Mitogen-Activated Protein Kinase Kinases

Associated data

  • PDB/1UWH
  • PDB/1UWJ