Cloning of mouse integrin αv cDNA and role of the αv-related matrix receptors in metanephric development

Abstract

Metanephrogenesis has been a long-standing model to study cell-matrix interactions. A number of adhesion molecules, including matrix receptors (i.e., integrins), are believed to be involved in such interactions. The integrins contain α and β subunits and are present in various tissues in different heterodimeric forms. In this study, one of the members of the integrin superfamily, αv, was characterized, and its relevance in murine nephrogenesis was investigated. Mouse embryonic renal cDNA libraries were prepared and screened for αv, and multiple clones were isolated and sequenced. The deduced amino acid sequence of the αv cDNA clones and hydropathic analysis revealed that it has a typical signal sequence and extracellular, transmembrane, and cytoplasmic domains, with multiple Ca2+ binding sites. No A(U)nA mRNA instability motifs were present. Conformational analysis revealed no rigid long-range-ordered structure in murine αv. The αv was expressed in the embryonic kidney at day 13 of the gestation, with a transcript size of ∼7 kb. Its expression increased progressively during the later gestational stages and in the neonatal period. It was distributed in the epithelial elements of developing nephrons and was absent in the uninduced mesenchyme. In mature metanephroi, the expression was relatively high in the glomeruli and blood vessels, as compared to the tubules. Various heterodimeric associations of αv, i.e., with β1, β3, β5, and β6, were observed in metanephric tissues. Inclusion of αv-antisense-oligodeoxynucleotide or -antibody in metanephric culture induced dysmorphogenesis of the kidney with reduced population of the nephrons, disorganization of the ureteric bud branches, and reduction of mRNA and protein expressions of αv. The expressions of integrin β3, β5, and β6 were unaltered. These findings suggest that the integrin αv is developmentally regulated, has a distinct spatio-temporal expression, and is relevant in the mammalian organogenesis.