ERK phosphorylation potentiates Elk-1-mediated ternary complex formation and transactivation

EMBO J. 1995 Mar 1;14(5):951-62.

Abstract

Induction of the human c-fos proto-oncogene by mitogens depends on the formation of a ternary complex by p62TCF with the serum response factor (SRF) and the serum response element (SRE). We demonstrate that Elk-1, a protein closely related to p62TCF in function, is a nuclear target of two members of the MAP kinase family, ERK1 and ERK2. Phosphorylation of Elk-1 increases the yield of ternary complex in vitro. At least five residues in the C-terminal domain of Elk-1 are phosphorylated upon growth factor stimulation of NIH3T3 cells. These residues are also phosphorylated by purified ERK1 in vitro, as determined by a combination of phosphopeptide sequencing and 2-D peptide mapping. Conversion of two of these phospho-acceptor sites to alanine impairs the formation of ternary complexes by the resulting Elk-1 proteins. Removal of these serine residues also drastically diminishes activation of the c-fos promoter in epidermal growth factor-treated cells. Analogous mutations at other sites impair activation to a lesser extent without affecting ternary complex formation in vitro. Our results indicate that phosphorylation regulates ternary complex formation by Elk-1, which is a prerequisite for the manifestation of its transactivation potential at the c-fos SRE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3T3 Cells
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • DNA / metabolism
  • DNA-Binding Proteins / metabolism*
  • DNA-Binding Proteins / physiology
  • Genes, fos / genetics
  • Humans
  • Mice
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases*
  • Molecular Sequence Data
  • PC12 Cells
  • Peptide Mapping
  • Phosphorylation
  • Promoter Regions, Genetic / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins / physiology
  • Rats
  • Recombinant Fusion Proteins / metabolism
  • Sequence Alignment
  • Sequence Analysis
  • Transcription Factors*
  • Transcriptional Activation / physiology*
  • ets-Domain Protein Elk-1

Substances

  • DNA-Binding Proteins
  • ELK1 protein, human
  • Elk1 protein, mouse
  • Elk1 protein, rat
  • Proto-Oncogene Proteins
  • Recombinant Fusion Proteins
  • Transcription Factors
  • ets-Domain Protein Elk-1
  • DNA
  • Calcium-Calmodulin-Dependent Protein Kinases
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 3
  • Mitogen-Activated Protein Kinases