The RNA-binding protein Seb4/RBM24 is a direct target of MyoD and is required for myogenesis during Xenopus early development

Mech Dev. May-Jun 2010;127(5-6):281-91. doi: 10.1016/j.mod.2010.03.002. Epub 2010 Mar 23.

Abstract

RNA-binding proteins play an important role to post-transcriptionally regulate gene expression. During early development they exhibit temporally and spatially regulated expression pattern. The expression of Xenopus laevis Seb4 gene, also known as RBM24 in other vertebrates, is restricted to the lateral and ventral mesoderm during gastrulation and then localized to the somitic mesoderm, in a similar pattern as XMyoD gene. Using a hormone-inducible form of MyoD to identify potential direct MyoD target genes, we find that Seb4 expression is directly regulated by MyoD at the gastrula stage. We further show that a 0.65kb X. tropicalis RBM24 regulatory region contains multiple E boxes (CANNTG), which are potential binding sites for MyoD and other bHLH proteins. By injecting a RBM24 reporter construct into the animal pole of X. laevis embryos, we find that this reporter gene is indeed specifically activated by MyoD and repressed by a dominant negative MyoD mutant. Knockdown of Seb4 produces similar effects as those obtained by the dominant negative MyoD mutant, indicating that it is required for the expression of myogenic genes and myogenesis in the embryo. In cultured ectodermal explants, although overexpression of Seb4 has no obvious effect on myogenesis, knockdown of Seb4 inhibits the expression of myogenic genes and myogenesis induced by MyoD. These results reveal that Seb4 is a target of MyoD during myogenesis and is required for myogenic gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • E-Box Elements / genetics
  • Embryo Culture Techniques
  • Gastrula / metabolism
  • Gene Expression Regulation, Developmental / genetics
  • Genes, Reporter
  • In Situ Hybridization
  • Mesoderm / metabolism
  • Muscle Development / genetics*
  • MyoD Protein / genetics*
  • MyoD Protein / metabolism
  • RNA-Binding Proteins / genetics*
  • RNA-Binding Proteins / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Signal Transduction / genetics
  • Xenopus Proteins / genetics*
  • Xenopus Proteins / metabolism
  • Xenopus laevis / genetics*
  • Xenopus laevis / metabolism

Substances

  • MyoD Protein
  • RBM24 protein, Xenopus
  • RNA-Binding Proteins
  • Xenopus Proteins