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Chicken Recombinant Limbs Assay to Understand Morphogenesis, Patterning, and Early Steps in Cell Differentiation
Published on: January 12, 2022
The aneurogenic limb identifies developmental cell interactions underlying vertebrate limb regeneration
Anoop Kumar1, Jean-Paul Delgado, Phillip B Gates
1Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London WC1E 6BT, United Kingdom.
Summary
Salamander limb regeneration is nerve-dependent, but aneurogenic limbs regenerate without nerves. High Anterior Gradient (AG) protein levels in aneurogenic limb epidermis enable nerve-independent regeneration, which is lost upon innervation.
Area of Science:
- Developmental Biology
- Regenerative Medicine
- Neuroscience
Background:
- Limb regeneration in salamanders is typically dependent on nerve signaling.
- The molecular mechanisms underlying nerve-dependent and nerve-independent regeneration are not fully understood.
- Anterior Gradient (AG) protein has been implicated in limb regeneration and acts as a growth factor.
Purpose of the Study:
- To investigate the role of Anterior Gradient (AG) protein in nerve-dependent and nerve-independent limb regeneration.
- To elucidate the molecular basis of tissue interactions during limb regeneration.
- To understand how innervation influences the regenerative capacity of limbs.
Main Methods:
- Studying aneurogenic limbs (lacking a neural tube) in salamander embryos.
- Analyzing the expression patterns of AG protein in normal and aneurogenic limbs.
- Observing changes in AG protein levels after transplantation and innervation.
Main Results:
- Aneurogenic limbs regenerate without nerves, becoming nerve-dependent only after innervation.
- AG protein is highly expressed in the epidermis of aneurogenic limbs throughout development and regeneration.
- Innervation leads to a decrease in AG protein levels in aneurogenic limbs and their epidermis.
- Aneurogenic epidermis exhibits a fivefold increase in secretory gland cells expressing AG protein.
Conclusions:
- Persistently high AG protein expression in the aneurogenic limb epidermis is crucial for nerve-independent regeneration.
- Innervation regulates the epidermal niche, initiating nerve dependence in limb regeneration.
- This regulation mechanism may have evolved in relation to limb regeneration, potentially explaining its absence in anuran limb development.
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