Spatially separate docking sites on ERK2 regulate distinct signaling events in vivo

Curr Biol. 2005 Jul 26;15(14):1319-24. doi: 10.1016/j.cub.2005.06.037.

Abstract

Inhibitors of the oncogenic Ras-MAPK pathway have been intensely pursued as therapeutics. Targeting this pathway, however, presents challenges due to the essential role of MAPK in homeostatic functions. The phosphorylation and activation of MAPK substrates is regulated by protein-protein interactions with MAPK docking sites. Active ERK1/2 (extracellular signal-regulated kinase 1/2)-MAPKs localize to effectors containing DEF (docking site for ERK, (F)/(Y) -X-(F)/(Y) -P)- or D-domain (docking domain) motifs. We have examined the in vivo activity of ERK2 mutants with impaired ability to signal via either docking site. Mutations in the DEF-domain binding pocket prevent activation of DEF-domain-containing effectors but not RSK (90 kDa ribosomal S6 kinase), which contains a D domain. Conversely, mutation of the ERK2 CD domain, which interacts with D domains, prevents RSK activation but not DEF-domain signaling. Uncoupling docking interactions does not compromise ERK2 phosphotransferase activity. ERK2 DEF mutants undergo regulated nuclear translocation but are defective for Elk-1/TCF transactivation and target gene induction. Thus, downstream branches of ERK2 signaling can be selectively inhibited without blocking total pathway activity. Significantly, several protooncogenes contain DEF domains and are regulated by ERK1/2. Therefore, disrupting ERK-DEF domain interactions could be an alternative to inhibiting oncogenic Ras-MAPK signaling.

Publication types

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

MeSH terms

  • Animals
  • Base Sequence
  • Blotting, Western
  • Fluorescent Antibody Technique
  • HeLa Cells
  • Humans
  • Mice
  • Mitogen-Activated Protein Kinase 1 / genetics
  • Mitogen-Activated Protein Kinase 1 / metabolism*
  • Models, Molecular*
  • Mutagenesis, Site-Directed
  • Mutation / genetics
  • NIH 3T3 Cells
  • Protein Binding
  • Protein Kinases / metabolism
  • Protein Structure, Tertiary
  • RNA, Small Interfering / genetics
  • Ribosomal Protein S6 Kinases
  • Signal Transduction / physiology*

Substances

  • RNA, Small Interfering
  • Protein Kinases
  • Ribosomal Protein S6 Kinases
  • Mitogen-Activated Protein Kinase 1