ILK Modulates Epithelial Polarity and Matrix Formation in Hair Follicles

The study demonstrated that integrin-linked kinase (ILK) played a crucial role in hair follicle morphogenesis by regulating epithelial polarity and matrix formation. In the absence of ILK, hair follicle matrix lineage development was disrupted due to defects in apical-basal cell polarity and laminin-511 and basement membrane assembly. This led to impaired hair matrix specification and absence of precortex and inner sheath root cell lineages. The molecular pathways affected in ILK-deficient follicles were similar to those lacking epidermal integrin β1, involving Wnt signaling but not sonic hedgehog signaling. Additionally, ILK-deficient hair buds exhibited abnormalities in the dermal papilla. Exogenous laminin-511 restored hair matrix formation markers, indicating ILK's upstream role in laminin-511 assembly and hair follicle development beyond the germ stage.