Differential mRNA Regulation of Integrin Subunits αv, β1, β3, and β5during Mouse Embryonic Organogenesis

Abstract

Cell interactions with extracellular matrices play important roles in morphogenetic processes during embryonic development. Extracellular matrix receptors of the integrin family have been implicated in these steps. Recent studies indicate that a variety of integrins can be differentially expressed during development, consistent with diverse roles for integrins in embryogenesis. The present study compares the expression patterns of several major members of the α_vintegrin subfamily, focusing on mRNA expression of α_v, β₁, β₃, and β₅subunits during mouse embryonic organogenesis using Northern blot analysis and in situhybridization. The α_vand β₁subunits showed widespread tissue expression, although most tissues expressed α_vat relatively low or basal levels. The mRNA for β₅was also expressed in a variety of embryonic organs and showed unusual localization patterns in certain organs. Striking, high-level expression of β₅transcripts was detected in the ependymal layer of the central nervous system, glomeruli of the kidney, epicardial region of the heart, and in the tooth germs, suggesting specific functions for this molecule during morphogenetic events in these organs. In contrast, few β₃transcripts were expressed during mid-gestation mouse embryogenesis except in megakaryocytes within the embryonic liver. These observations of differing expression spectra suggest that members of the α_v, integrin subfamily have distinct roles and also suggests that they have different transcriptional regulation. The β₅integrin is unique in its degree of tissue-specific mRNA regulation associated with morphogenesis of embryonic organs.