β1-Integrins are involved in migration of human fetal tracheal epithelial cells and tubular morphogenesis

Abstract

Development of human fetal airways requires interaction of the respiratory epithelium and the extracellular matrix through integrins. Nevertheless, the specific roles of β1-integrins during development and tubular morphogenesis are still unknown. To analyze β1-integrin localization and influence during migration, we developed a model of human fetal tracheal explants growing on collagen and overlaid with a second layer of collagen to form a sandwich. In this configuration, cord and tubule formation proceeded normally but were inhibited by incubation with anti-β1-integrin subunit antibodies. On a collagen matrix, β1-integrins were immunolocalized on the entire plasma membrane of migrating epithelial cells and almost exclusively on the basal plasma membrane of nonmigratory epithelial cells. In a sandwich configuration, β1-integrins became detectable in the cytoplasm of epithelial cells. Coating cultures with collagen transiently altered the morphology of migrating cells and their speed and direction of migration, whereas incubation with anti-β1-integrin subunit antibodies irreversibly altered these parameters. These observations suggest that the matrix environment, by modulating β1-integrin expression patterns, plays a key role during tubular morphogenesis of human fetal tracheal epithelium, principally by modulating epithelial cell migration.