Differential expression of integrin alpha chains by renal epithelial cells

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Abstract
We have investigated the expression of integrin chains by human renal epithelial cells during in vivo renal differentiation and in vitro cell culture on different extracellular matrices. Using the immunoperoxidase technique to visualize the binding of monoclonal antibodies to different integrin chains in fetal and adult kidneys, we found a change during development from α1β1, α3β1, and α4β1 -positive blastemal cells to α2β1, α3β1, and α6β1 -positive epithelial cells. The pattern of integrin expression correlates with the presence in the extracellular matrix of the appropriate ligands. In in vitro cell culture experiments, renal epithelium expressed α3 and α5 integrins on all extracellular matrices. Integrins α2 and α6 were found only in cells grown on a laminin-containing substratum. Fibronectin and α5 integrin co-localized on the ventral surface of cells grown on a laminin substratum and at the periphery of cells on glass coverslips. These results suggest that there is a close relationship between integrin α chain usage and the presence of appropriate ligands in the extracellular matrix.