Musashi protein-directed translational activation of target mRNAs is mediated by the poly(A) polymerase, germ line development defective-2

J Biol Chem. 2014 May 16;289(20):14239-51. doi: 10.1074/jbc.M114.548271. Epub 2014 Mar 18.

Abstract

The mRNA-binding protein, Musashi, has been shown to regulate translation of select mRNAs and to control cellular identity in both stem cells and cancer cells. Within the mammalian cells, Musashi has traditionally been characterized as a repressor of translation. However, we have demonstrated that Musashi is an activator of translation in progesterone-stimulated oocytes of the frog Xenopus laevis, and recent evidence has revealed Musashi's capability to function as an activator of translation in mammalian systems. The molecular mechanism by which Musashi directs activation of target mRNAs has not been elucidated. Here, we report a specific association of Musashi with the noncanonical poly(A) polymerase germ line development defective-2 (GLD2) and map the association domain to 31 amino acids within the C-terminal domain of Musashi. We show that loss of GLD2 interaction through deletion of the binding domain or treatment with antisense oligonucleotides compromises Musashi function. Additionally, we demonstrate that overexpression of both Musashi and GLD2 significantly enhances Musashi function. Finally, we report a similar co-association also occurs between murine Musashi and GLD2 orthologs, suggesting that coupling of Musashi to the polyadenylation apparatus is a conserved mechanism to promote target mRNA translation.

Keywords: Oocyte; Polyadenylation; RNA-binding Protein; Translation Control; Xenopus.

Publication types

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

MeSH terms

  • Animals
  • Cell Cycle
  • Cytoplasm / metabolism
  • Gene Expression Regulation*
  • Mice
  • Nerve Tissue Proteins / metabolism*
  • Polyadenylation
  • Polynucleotide Adenylyltransferase / metabolism*
  • Protein Biosynthesis*
  • RNA, Messenger / genetics
  • RNA-Binding Proteins / metabolism*
  • Ribonucleoproteins
  • Substrate Specificity
  • Xenopus Proteins / metabolism*
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism

Substances

  • Nerve Tissue Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • Ribonucleoproteins
  • Xenopus Proteins
  • Msi1 protein, Xenopus
  • Polynucleotide Adenylyltransferase
  • TENT2 protein, Xenopus