Col4a2-eGFP Mouse Model Reveals the Molecular and Functional Dynamics of Basement Membrane Remodelling in Hair Follicle Morphogenesis

The study developed a mouse model with a fluorescently tagged collagen IV gene (Col4a2) to visualize basement membrane (BM) dynamics during hair follicle morphogenesis. Live imaging showed a spatial gradient in COL4A2 turnover rate that matched BM expansion rate. Epithelial progenitor proliferation was linked to BM expansion, and these progenitors followed the BM as it expanded but did not migrate on stable BM. Inhibiting matrix metalloproteinase delayed COL4A2 turnover, restricted BM expansion, and caused a shift in the division angle of epithelial progenitors, which in turn affected hair follicle morphology. This research highlights the importance of BM dynamics in regulating cell proliferation, movement, and organ shape during development.