Hemidesmosomes And Notch Signaling Regulate Epidermal Differentiation Via Delamination

This study investigates the role of integrins, specifically integrin-β4, in the adhesion and differentiation of basal keratinocytes in the epidermis. Using a lentiviral-mediated approach to induce mosaic, epidermal-specific loss of integrin-β4 or its ligand laminin-α3β3ɣ2, the researchers found that while these mutations cause postnatal skin blistering, they do not lead to epidermal-dermal separation during embryonic development. The loss of integrin-β4 results in mild defects in cell division orientation and increased differentiation via delamination, where basal keratinocytes transition to the suprabasal layer. Additionally, hyperactive Notch signaling decreases integrin-β4 expression and enhances delamination, whereas deletion of the Notch effector Rbpj has the opposite effect. The findings highlight the critical role of hemidesmosomes in epidermal differentiation through both mitotic and non-mitotic mechanisms.