Homeostatic interactions between MEKK3 and TAK1 involved in NF-kappaB signaling

Cell Signal. 2008 Apr;20(4):705-13. doi: 10.1016/j.cellsig.2007.12.007. Epub 2008 Jan 18.

Abstract

Several members of the mitogen-activated protein kinase kinase kinase (MAP3K) family including MEKK3 and TGFbeta-activating kinase (TAK1) play nonredundant roles in activation of the NF-kappaB transcription factor. However, the mechanism by which MEKK3 mediates NF-kappaB signaling is not fully understood. In this report we investigate the association of murine MEKK3 with other proteins and their roles in NF-kappaB activation. Using tandem affinity purification TAK1 was identified as an endogenous protein that interacts with MEKK3. MEKK3-TAK1 interactions were confirmed by fluorescence resonance energy transfer and coimmunoprecipitation. MEKK3-TAK1 complexes contain non-phosphorylated forms of both molecules. Expression of non-phosphorylated TAK1 interferes with MEKK3 phosphorylation and NF-kappaB reporter activity induced by transient MEKK3 expression or TNFalpha stimulation. Addition of TAB1 facilitates TAK1 autophosphorylation and reverses the inhibitory effects of TAK1 on MEKK3 phosphorylation and NF-kappaB signal transduction in human 293 cells and TAK1 deficient mouse embryonic fibroblasts. The data provide insights into the homeostatic interactions that maintain basal NF-kappaB levels by holding the enzymes MEKK3 and TAK1 in their inactive state.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • Chromatography, Affinity
  • Enzyme Activation
  • Epithelial Cells / enzymology
  • Epithelial Cells / metabolism
  • Fibroblasts / enzymology
  • Fibroblasts / metabolism
  • Fluorescence Resonance Energy Transfer
  • Homeostasis
  • Humans
  • Intracellular Signaling Peptides and Proteins / metabolism
  • MAP Kinase Kinase Kinase 3 / genetics
  • MAP Kinase Kinase Kinase 3 / metabolism*
  • MAP Kinase Kinase Kinases / deficiency
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • Mice
  • Mutation
  • NF-kappa B / metabolism*
  • Phosphorylation
  • Protein Binding
  • Signal Transduction*
  • Transfection
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Intracellular Signaling Peptides and Proteins
  • NF-kappa B
  • TAB1 protein, MAPKKK activator, vertebrate
  • Tumor Necrosis Factor-alpha
  • MAP Kinase Kinase Kinase 3
  • MAP Kinase Kinase Kinases
  • MAP kinase kinase kinase 7
  • Map3k3 protein, mouse