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Sonic hedgehog signaling is essential for hair development
B St-Jacques1, H R Dassule, I Karavanova
1Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Current Biology : CB
|October 13, 1998
Summary
Sonic hedgehog (Shh) signaling is crucial for hair follicle ingrowth and development. While not essential for initial formation, Shh controls key morphogenetic processes, ensuring proper hair shaft production.
Area of Science:
- Developmental Biology
- Dermatology
- Genetics
Background:
- Vertebrate skin forms diverse epidermal structures like scales, feathers, and hair from epidermal placodes.
- Epithelial-mesenchymal interactions and signaling pathways (Wnt, Hedgehog, BMP) are critical for initiating hair follicle formation.
- Sonic hedgehog (Shh) expression is observed during hair follicle development, particularly in the hair matrix and dermal papilla.
Purpose of the Study:
- To investigate the specific role of Sonic hedgehog (Shh) signaling in hair follicle development using Shh null mutant mice.
Main Methods:
- Analysis of Shh null mutant mouse embryos to observe hair follicle development.
- Grafting of Shh mutant skin onto nude mice to assess follicle formation and hair growth.
- Gene expression analysis of Wnt10b, Bmp2, and Bmp4 during follicle development.
Main Results:
- Hair follicle development arrested post-epidermal-dermal interaction in Shh mutant embryos, despite continued Wnt10b, Bmp2, and Bmp4 expression.
- Grafted Shh mutant skin formed abnormal, large follicles with small dermal papillae, exhibiting proliferation and differentiation but no hair formation.
- Shh signaling is not required for the initiation of hair follicle development.
Conclusions:
- Sonic hedgehog (Shh) signaling is essential for controlling hair follicle ingrowth and morphogenesis.
- Shh plays a critical role in the later stages of hair follicle development, ensuring proper structure and function.