Level-specific role of paraxial mesoderm in regulation of Tbx5/Tbx4 expression and limb initiation

Dev Biol. 2006 Apr 1;292(1):79-89. doi: 10.1016/j.ydbio.2006.01.002. Epub 2006 Feb 15.

Abstract

Tetrapod limbs, forelimbs and hindlimbs, emerge as limb buds during development from appropriate positions along the rostro-caudal axis of the main body. In this study, tissue interactions by which rostro-caudal level-specific limb initiation is established were analyzed. The limb bud originates from the lateral plate located laterally to the paraxial mesoderm, and we obtained evidence that level-specific tissue interactions between the paraxial mesoderm and the lateral plate mesoderm are important for the determination of the limb-type-specific gene expression and limb outgrowth. When the wing-level paraxial mesoderm was transplanted into the presumptive leg region, the wing-level paraxial mesoderm upregulated the expression of Tbx5, a wing marker gene, and down regulated the expression of Tbx4 and Pitx1, leg marker genes, in the leg-level lateral plate. The wing-level paraxial mesoderm relocated into the leg level also inhibited outgrowth of the hindlimb bud and down regulated Fgf10 and Fgf8 expression, demonstrating that the wing-level paraxial mesoderm cannot substitute for the function of the leg-level paraxial mesoderm in initiation and outgrowth of the hindlimb. The paraxial mesoderm taken from the neck- and flank-level regions also had effects on Tbx5/Tbx4 expression with different efficiencies. These findings suggest that the paraxial mesoderm has level-specific abilities along the rostro-caudal axis in the limb-type-specific mechanism for limb initiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Avian Proteins / biosynthesis*
  • Avian Proteins / genetics
  • Chick Embryo
  • Down-Regulation / genetics
  • Fibroblast Growth Factor 10 / antagonists & inhibitors
  • Fibroblast Growth Factor 10 / genetics
  • Fibroblast Growth Factor 8 / antagonists & inhibitors
  • Fibroblast Growth Factor 8 / genetics
  • Hindlimb / embryology
  • Hindlimb / growth & development
  • Lower Extremity / embryology*
  • Lower Extremity / growth & development
  • Mesoderm / physiology*
  • Mesoderm / transplantation
  • Organ Culture Techniques
  • Paired Box Transcription Factors / antagonists & inhibitors
  • Paired Box Transcription Factors / genetics
  • T-Box Domain Proteins / biosynthesis*
  • T-Box Domain Proteins / genetics
  • Wings, Animal / embryology*
  • Wings, Animal / growth & development

Substances

  • Avian Proteins
  • Fibroblast Growth Factor 10
  • Paired Box Transcription Factors
  • T-Box Domain Proteins
  • T-box transcription factor 5
  • TBX4 protein, Gallus gallus
  • homeobox protein PITX1
  • Fibroblast Growth Factor 8