Inhibition of Mitogen-activated Protein Kinase (MAPK)-interacting Kinase (MNK) Preferentially Affects Translation of mRNAs Containing Both a 5'-Terminal Cap and Hairpin

J Biol Chem. 2016 Feb 12;291(7):3455-67. doi: 10.1074/jbc.M115.694190. Epub 2015 Dec 14.

Abstract

The MAPK-interacting kinases 1 and 2 (MNK1 and MNK2) are activated by extracellular signal-regulated kinases 1 and 2 (ERK1/2) or p38 in response to cellular stress and extracellular stimuli that include growth factors, cytokines, and hormones. Modulation of MNK activity affects translation of mRNAs involved in the cell cycle, cancer progression, and cell survival. However, the mechanism by which MNK selectively affects translation of these mRNAs is not understood. MNK binds eukaryotic translation initiation factor 4G (eIF4G) and phosphorylates the cap-binding protein eIF4E. Using a cell-free translation system from rabbit reticulocytes programmed with mRNAs containing different 5'-ends, we show that an MNK inhibitor, CGP57380, affects translation of only those mRNAs that contain both a cap and a hairpin in the 5'-UTR. Similarly, a C-terminal fragment of human eIF4G-1, eIF4G(1357-1600), which prevents binding of MNK to intact eIF4G, reduces eIF4E phosphorylation and inhibits translation of only capped and hairpin-containing mRNAs. Analysis of proteins bound to m(7)GTP-Sepharose reveals that both CGP and eIF4G(1357-1600) decrease binding of eIF4E to eIF4G. These data suggest that MNK stimulates translation only of mRNAs containing both a cap and 5'-terminal RNA duplex via eIF4E phosphorylation, thereby enhancing the coupled cap-binding and RNA-unwinding activities of eIF4F.

Keywords: eukaryotic translation initiation; eukaryotic translation initiation factor 4E (eIF4E); eukaryotic translation initiation factor 4G (eIF4G); mRNA; phosphorylation.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Substitution
  • Animals
  • Cell-Free System / drug effects
  • Cell-Free System / enzymology
  • Cell-Free System / metabolism
  • Eukaryotic Initiation Factor-4E / chemistry
  • Eukaryotic Initiation Factor-4E / genetics
  • Eukaryotic Initiation Factor-4E / metabolism*
  • Eukaryotic Initiation Factor-4G / chemistry
  • Eukaryotic Initiation Factor-4G / genetics
  • Eukaryotic Initiation Factor-4G / metabolism*
  • Humans
  • Intracellular Signaling Peptides and Proteins / antagonists & inhibitors
  • Intracellular Signaling Peptides and Proteins / chemistry
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Inverted Repeat Sequences
  • Mutant Proteins / antagonists & inhibitors
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Peptide Fragments / antagonists & inhibitors
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Phosphorylation / drug effects
  • Protein Biosynthesis / drug effects*
  • Protein Interaction Domains and Motifs
  • Protein Kinase Inhibitors / pharmacology
  • Protein Processing, Post-Translational / drug effects
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / chemistry
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / metabolism*
  • RNA / chemistry
  • RNA / metabolism
  • RNA Caps / chemistry
  • RNA Caps / metabolism*
  • RNA Folding / drug effects
  • RNA, Messenger / chemistry
  • RNA, Messenger / metabolism*
  • Rabbits
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Reticulocytes / drug effects
  • Reticulocytes / enzymology
  • Reticulocytes / metabolism

Substances

  • EIF4G1 protein, human
  • Eukaryotic Initiation Factor-4E
  • Eukaryotic Initiation Factor-4G
  • Intracellular Signaling Peptides and Proteins
  • Mutant Proteins
  • Peptide Fragments
  • Protein Kinase Inhibitors
  • RNA Caps
  • RNA, Messenger
  • RNA, recombinant
  • Recombinant Proteins
  • RNA
  • MKNK1 protein, human
  • MKNK2 protein, human
  • Protein-Serine-Threonine Kinases