An eGFP-Col4a2 mouse model reveals basement membrane dynamics underlying hair follicle morphogenesis

Area of Science:

• Developmental Biology
• Cell Biology
• Biophysics

Background:

• Basement membrane (BM) remodeling is essential for tissue development and morphogenesis.
• Understanding the molecular dynamics and tissue-level behavior of the BM in mammals is limited by visualization tools.

Purpose of the Study:

• To investigate the dynamics of basement membrane (BM) remodeling during mammalian development.
• To elucidate the role of collagen IV (COL4A2) dynamics in hair follicle morphogenesis.
• To understand how BM expansion influences epithelial progenitor cell behavior.

Main Methods:

• Development of genetically engineered mouse lines with fluorescently tagged collagen IV (COL4A2).
• Live imaging techniques to visualize BM dynamics in developing hair follicles.
• Pharmacological inhibition of matrix metalloproteinases to assess BM remodeling effects.

Main Results:

• A spatial gradient in COL4A2 turnover rate was observed, correlating with BM expansion and epithelial progenitor proliferation.
• Epithelial progenitors are displaced by expanding BMs, not by active migration on stationary BMs.
• Matrix metalloproteinase inhibition slowed COL4A2 turnover, restricted BM expansion, and altered progenitor cell division, impacting hair follicle morphology.

Conclusions:

• Spatially distinct basement membrane (BM) dynamics are critical for orchestrating progenitor cell behavior during organ development.
• BM expansion, driven by collagen IV dynamics, plays a key role in directing epithelial progenitor displacement and organ shaping.
• Targeting BM remodeling pathways offers potential for understanding and manipulating organ development.