INTEGRIN-MEDIATED INTERACTIONS BETWEEN PRIMARY T-SV40 IMMORTALIZED HUMAN GLOMERULAR EPITHELIAL-CELLS AND TYPE-IV COLLAGEN/

The use of human glomerular epithelial cells (HGEC) in research has be en severely restricted by several obstacles, which have been circumven ted by the generation of T-SV40 immortalized human visceral glomerular epithelial cells (Delarue et al, 1991). In this work, we compared the primary and immortalized HGEC for expression of integrin and some non integrin surface receptors. We also studied the adhesion of both types of HGEC to glomerular basement membrane (GEM), type IV collagen (tIV) , and its major noncollagenous NC1 domain. The integrins mediating adh esion of HGEC to tIV were also examined. Expression of integrin and so me nonintegrin cell surface receptors was analyzed by flow cytometry. Adhesion to GBM, tIV, and its major noncollagenous NC1 domain was stud ied by direct solid phase cell adhesion assays. Identification of inte grins mediating adhesion of HGEC to tIV was achieved by inhibition of cell adhesion using monoclonal antibodies to integrin subunits. The pr imary and immortalized HGEC share phenotypic characteristics, and alph a(3) beta(1) appeared to be the major integrin present on both HGEC ty pes. The kinetics of binding to GEM, tIV, and its noncollagenous NC1 d omain were similar in both the primary and immortalized HGEC, although the latter displayed a somewhat weaker binding. Both the primary and immortalized HGEC displayed significantly better adhesion to NC1-alpha (3) compared with NC1-alpha(1.) alpha(3) beta(1) appears to be the maj or integrin mediating the adhesion of HGEC to tIV.Our studies suggest that alpha(3) beta(1) is the major integrin present on HGEC. This has been confirmed by flow cytometric analysis. In addition, we demonstrat ed a functional role for this integrin in mediating attachment of HGEC to tIV. Our data also demonstrate a preference in binding of HGEC to alpha 3 chains of NC1 compared with alpha 1 chains of NC1. These findi ngs were seen in both the primary and immortalized HGEC. The T-SV40 im mortalized HGEC can therefore serve as a very useful tool to study glo merular visceral cell biology.