IκB kinase-induced interaction of TPL-2 kinase with 14-3-3 is essential for Toll-like receptor activation of ERK-1 and -2 MAP kinases

Proc Natl Acad Sci U S A. 2014 Jun 10;111(23):E2394-403. doi: 10.1073/pnas.1320440111. Epub 2014 May 27.

Abstract

The MEK-1/2 kinase TPL-2 is critical for Toll-like receptor activation of the ERK-1/2 MAP kinase pathway during inflammatory responses, but it can transform cells following C-terminal truncation. IκB kinase (IKK) complex phosphorylation of the TPL-2 C terminus regulates full-length TPL-2 activation of ERK-1/2 by a mechanism that has remained obscure. Here, we show that TPL-2 Ser-400 phosphorylation by IKK and TPL-2 Ser-443 autophosphorylation cooperated to trigger TPL-2 association with 14-3-3. Recruitment of 14-3-3 to the phosphorylated C terminus stimulated TPL-2 MEK-1 kinase activity, which was essential for TPL-2 activation of ERK-1/2. The binding of 14-3-3 to TPL-2 was also indispensible for lipopolysaccharide-induced production of tumor necrosis factor by macrophages, which is regulated by TPL-2 independently of ERK-1/2 activation. Our data identify a key step in the activation of TPL-2 signaling and provide a mechanistic insight into how C-terminal deletion triggers the oncogenic potential of TPL-2 by rendering its kinase activity independent of 14-3-3 binding.

Keywords: MAP3K8; NF-κB; inflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 14-3-3 Proteins / genetics
  • 14-3-3 Proteins / metabolism*
  • Animals
  • Cells, Cultured
  • Enzyme Activation
  • HEK293 Cells
  • Humans
  • I-kappa B Kinase / metabolism*
  • Immunoblotting
  • Lipopolysaccharides / pharmacology
  • MAP Kinase Kinase Kinases / genetics
  • MAP Kinase Kinase Kinases / metabolism*
  • MAP Kinase Signaling System
  • Macrophages / drug effects
  • Macrophages / metabolism
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Mitogen-Activated Protein Kinase 3 / metabolism*
  • NF-kappa B p50 Subunit / genetics
  • NF-kappa B p50 Subunit / metabolism
  • Phosphorylation
  • Protein Binding
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Serine / genetics
  • Serine / metabolism
  • Toll-Like Receptors / metabolism*
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • 14-3-3 Proteins
  • Lipopolysaccharides
  • NF-kappa B p50 Subunit
  • Proto-Oncogene Proteins
  • Toll-Like Receptors
  • Tumor Necrosis Factor-alpha
  • Nfkb1 protein, mouse
  • Serine
  • I-kappa B Kinase
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • MAP Kinase Kinase Kinases
  • Map3k8 protein, mouse