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Xenopus sonic hedgehog as a potential morphogen during embryogenesis and thyroid hormone-dependent metamorphosis
1Laboratory of Molecular Embryology, National Institute of Child Health and Human Development, Bethesda, MD 20892-5430, USA.
Nucleic Acids Research
|July 11, 1995
Summary
We identified a novel gene, Xenopus hedgehog (Xhh), crucial for amphibian development and metamorphosis. This thyroid hormone-responsive gene plays a role in organogenesis and tissue patterning during tadpole development.
Area of Science:
- Developmental Biology
- Molecular Endocrinology
- Amphibian Genetics
Background:
- Hedgehog proteins are key signaling molecules regulating cell position and tissue patterning.
- Thyroid hormone (TH) orchestrates amphibian metamorphosis, involving significant organ remodeling.
Purpose of the Study:
- To clone and characterize a Xenopus laevis hedgehog homologue (Xhh).
- To investigate the role of TH in regulating Xhh expression during metamorphosis.
Main Methods:
- Subtractive hybridization screening to identify TH-induced genes.
- Quantitative analysis of Xhh mRNA expression during metamorphosis.
- Whole mount in situ hybridization to determine spatial expression patterns.
Main Results:
- Xenopus hedgehog (Xhh) was cloned and characterized as a sonic hedgehog homologue.
- Xhh expression is significantly upregulated in the intestine during metamorphic climax (stage 62).
- Thyroid hormone directly induces Xhh expression, which is also observed in limbs, pancreas, and stomach.
Conclusions:
- Xhh is a direct thyroid hormone response gene involved in organogenesis during amphibian development.
- Xhh expression patterns suggest roles in both embryogenesis and metamorphosis, particularly in the notochord and floor plate.
- This study highlights the conserved function of hedgehog genes in vertebrate development.