Suppression of Raf-1 kinase activity and MAP kinase signalling by RKIP

Nature. 1999 Sep 9;401(6749):173-7. doi: 10.1038/43686.

Abstract

Raf-1 phosphorylates and activates MEK-1, a kinase that activates the extracellular signal regulated kinases (ERK). This kinase cascade controls the proliferation and differentiation of different cell types. Here we describe a Raf-1-interacting protein, isolated using a yeast two-hybrid screen. This protein inhibits the phosphorylation and activation of MEK by Raf-1 and is designated RKIP (Raf kinase inhibitor protein). In vitro, RKIP binds to Raf-1, MEK and ERK, but not to Ras. RKIP co-immunoprecipitates with Raf-1 and MEK from cell lysates and colocalizes with Raf-1 when examined by confocal microscopy. RKIP is not a substrate for Raf-1 or MEK, but competitively disrupts the interaction between these kinases. RKIP overexpression interferes with the activation of MEK and ERK, induction of AP-1-dependent reporter genes and transformation elicited by an oncogenically activated Raf-1 kinase. Downregulation of endogenous RKIP by expression of antisense RNA or antibody microinjection induces the activation of MEK-, ERK- and AP-1-dependent transcription. RKIP represents a new class of protein-kinase-inhibitor protein that regulates the activity of the Raf/MEK/ERK module.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3T3 Cells
  • Androgen-Binding Protein*
  • Animals
  • COS Cells
  • Calcium-Calmodulin-Dependent Protein Kinases / antagonists & inhibitors*
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism
  • Carrier Proteins / isolation & purification
  • Carrier Proteins / metabolism*
  • Cell Transformation, Neoplastic
  • Cloning, Molecular
  • Enzyme Activation
  • Enzyme Inhibitors / metabolism
  • Gene Expression Regulation
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins / genetics
  • MAP Kinase Kinase Kinase 1*
  • Mice
  • Phosphatidylethanolamine Binding Protein
  • Phospholipid Transfer Proteins
  • Prostatein
  • Protein-Serine-Threonine Kinases / metabolism
  • Proto-Oncogene Proteins c-raf / antagonists & inhibitors*
  • Proto-Oncogene Proteins c-raf / metabolism
  • Rats
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Secretoglobins
  • Signal Transduction / drug effects*
  • Transcription Factor AP-1 / metabolism
  • Uteroglobin

Substances

  • Androgen-Binding Protein
  • Carrier Proteins
  • Enzyme Inhibitors
  • Luminescent Proteins
  • PEBP1 protein, human
  • Phosphatidylethanolamine Binding Protein
  • Phospholipid Transfer Proteins
  • Prostatein
  • Recombinant Proteins
  • Scgb1d2 protein, rat
  • Scgb1d4 protein, rat
  • Scgb2a2 protein, rat
  • Secretoglobins
  • Transcription Factor AP-1
  • Green Fluorescent Proteins
  • Uteroglobin
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-raf
  • Calcium-Calmodulin-Dependent Protein Kinases
  • MAP Kinase Kinase Kinase 1
  • MAP3K1 protein, human
  • Map3k1 protein, mouse