Integrin receptors and function on cultured glomerular endothelial cells

Abstract

Integrin expression and function on a cloned line of rat glomerular endothelial cells (GEndoC) were studied in an effort to obtain a better understanding of the means by which these cells interact with components of the glomerular basement membrane. Cultured GEndoC adhered to fibronectin, laminin and types I and IV collagen and expressed α1β1, α2β1, α3β1, α5β1, αvβ1 and αvβ3 integrins. Synthetic RGDS peptides significantly decreased adhesion to fibronectin (53.1 ± 4.7% of control). Antibody to rat β1 integrin strongly inhibited adhesion to laminin, fibronectin and types I and IV collagen (11.2, 19.0, 67.3 and 31.9% of control adhesion, respectively), while antibody to the rat α1 integrin chain strongly inhibited adhesion to laminin (65.2% of control), but only mildly inhibited adhesion to type IV collagen (77.2% of control) and did not affect adhesion to type I collagen (97.8% of control). Affinity chromatography of GEndoC lysates on a column of immobilized type I collagen displayed predominantly binding of α3β1 integrin with trace amounts of α1β1 and α2β1, documenting the major role of α3β1 in GEndoC adhesion to collagen. Chromatography on the immobilized cell-binding fragment of fibronectin revealed the α5β1, integrin to be the major fibronectin receptor on these cells, but antibody to αvβ3 integrin also documented a minor role for αvβ1 or αvβ3 in fibronectin adhesion. Cultured GEndoC express a similar array of integrin receptors in vitro as they do in vivo. Further study of the function of these receptors in normal and diseased glomeruli may provide important insights into the pathogenesis of disease states characterized by endothelial detachment or subendothelial protein deposition.