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Dissection, Culture, and Analysis of Xenopus laevis Embryonic Retinal Tissue
Published on: December 23, 2012
Xenopus hindbrain patterning requires retinoid signaling
1Whitehead Institute for Biomedical Research, Nine Cambridge Center, Cambridge, Massachusetts 02142, USA.
Developmental Biology
|January 24, 1998
Summary
Retinoic acid (RA) and fibroblast growth factor (FGF) pattern the Xenopus nervous system. RA and FGF signals pattern largely nonoverlapping regions along the anteroposterior axis, with posterior neural patterning requiring multiple inducers.
Area of Science:
- Developmental Biology
- Neuroscience
- Molecular Biology
Background:
- Understanding anteroposterior (A/P) patterning in Xenopus is crucial for comprehending neural development.
- The precise role of endogenous retinoids in A/P patterning remains unclear, despite their known effects on gene expression.
- HoxD1 serves as an early posterior neurectodermal marker, with its expression sensitive to retinoic acid.
Purpose of the Study:
- To investigate the role of endogenous retinoic acid (RA) in patterning posterior neural tissue in Xenopus.
- To determine the necessity of retinoid signaling in the ectoderm for the induction of posterior neural markers like HoxD1.
- To compare the posteriorizing effects of RA and fibroblast growth factor (FGF) on anterior neurectoderm.
Main Methods:
- Utilized a truncated retinoic acid receptor alpha2.2 (RARDelta) to interfere with retinoid signaling in Xenopus embryos.
- Analyzed the expression patterns of posterior neural markers (HoxD1, Krox-20) and anterior/posterior markers in injected embryos.
- Constructed conjugates of ectoderm and dorsolateral mesoderm to assess cell-autonomous requirements for retinoid signaling.
- Compared the posteriorizing capacity of RA and FGF on isolated anterior neurectoderm.
Main Results:
- Injection of RARDelta eliminated HoxD1 expression, indicating retinoid signaling is required for its induction.
- Retinoid receptors are necessary within the ectoderm for HoxD1 induction.
- Krox-20 expression in the hindbrain was compressed, suggesting elimination of specific hindbrain rhombomeres (r5).
- RARalpha2.2 expression overlapped with HoxD1, suggesting a direct activation role.
- Neither anterior nor more posterior neural gene expression was affected by RARDelta, highlighting the posterior hindbrain's sensitivity.
- Both RA and FGF can posteriorize anterior neurectoderm, but act in distinct domains and are less potent than posterior mesoderm.
Conclusions:
- Endogenous retinoid signaling is essential for patterning the posterior hindbrain in Xenopus.
- RA and FGF act on largely nonoverlapping regions of the A/P axis during neural patterning.
- Posterior neural development in Xenopus likely requires the integration of multiple signaling pathways, including RA and FGF.
