Regulation of Hoxb4 induction after neurulation by somite signal and neural competence

Gayana S Amirthalingam, Sara Howard, Susana Alvarez, Angel R de Lera, Nobue Itasaki

Research output: Contribution to journalArticle (Academic Journal)peer-review

4 Citations (Scopus)
336 Downloads (Pure)

Abstract

BACKGROUND: While the body axis is largely patterned along the anterior-posterior (A-P) axis during gastrulation, the central nervous system (CNS) shows dynamic changes in the expression pattern of Hox genes during neurulation, suggesting that the CNS refines the A-P pattern continuously after neural tube formation. This study aims at clarifying the role of somites in up-regulating Hoxb4 expression to eventually establish its final pattern and how the neural tube develops a competence to respond to extrinsic signals.

RESULTS: We show that somites are required for the up-regulation of Hoxb4 in the neural tube at the level of somites 1 to 5, the anterior-most domain of expression. However, each somite immediately adjacent to the neural tube is not sufficient at each level; planar signaling is additionally required particularly at the anterior-most segments of the expression domain. We also show that the dorsal side of the neural tube has a greater susceptibility to expressing Hoxb4 than the ventral region, a feature associated with dorsalization of the neural tube by BMP signals. BMP4 is additionally able to up-regulate Hoxb4 ventrally, but the effect is restricted to the axial levels at which Hoxb4 is normally expressed, and only in the presence of retinoic acid (RA) or somites, suggesting a role for BMP in rendering the neural tube competent to express Hoxb4 in response to RA or somite signals.

CONCLUSION: In identifying the collaboration between somites and neural tube competence in the induction of Hoxb4, this study demonstrates interplay between A-P and dorsal-ventral (D-V) patterning systems, whereby a specific feature of D-V polarity may be a prerequisite for proper A-P patterning by Hox genes.

Original languageEnglish
Article number17
Number of pages18
JournalBMC Developmental Biology
Volume9
DOIs
Publication statusPublished - 25 Feb 2009

Keywords

  • Animals
  • Body Patterning
  • Chick Embryo
  • Gene Expression Regulation, Developmental
  • Homeodomain Proteins
  • Mesoderm
  • Neural Tube
  • Neurulation
  • Signal Transduction
  • Somites
  • Tretinoin
  • Up-Regulation

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