Beta ig-h3 promotes renal proximal tubular epithelial cell adhesion, migration and proliferation through the interaction with alpha3beta1 integrin

Betaig-h3 (betaig-h3) is a secretory protein composed of fasciclin I-like repeats containing sequences that allows binding of integrins and glycosaminoglycans in vivo. Expression of betaig-h3 is responsive to TGF-beta and the protein is found to be associated with extracellular matrix (ECM) molecules, implicating betaig-h3 as an ECM adhesive protein of developmental processes. We previously observed predominant expression of betaig-h3 expression in the basement membrane of proximal tubules of kidney. In this study, the physiological relevance of such localized expression of betaig-h3 was examined in the renal proximal tubular epithelial cells (RPTEC). RPTEC constitutively expressed betaig-h3 and the expression was dramatically induced by exogenous TGF-beta1 treatment. betaig-h3 and its second and fourth FAS1 domain were able to mediate RPTEC adhesion, spreading and migration. Two known alpha3beta1 integrin-interaction motifs including aspartatic acid and isoleucine residues, NKDIL and EPDIM in betaig-h3 were responsible to mediate RPTEC adhesion, spreading, and migration. By using specific antibodies against integrins, we confirmed that alpha3beta1 integrin mediates the adhesion and migration of RPTECs on betaig-h3. In addition, it also enhanced proliferation of RPTECs through NKDIL and EPDIM. These results indicate that betaig-h3 mediates adhesion, spreading, migration and proliferation of RPTECs through the interaction with alpha3beta1 integrin and is intimately involved in the maintenance and the regeneration of renal proximal tubular epithelium.

Expression of alpha3beta1 Integrin in ECV304 Endothelial Cells and Angiogenesis / 대한해부학회지

Angiogenesis is a fundamental biological process including endothelial cell adhesion, migration, invasion and tube formation. Integrin receptors of endothelial cells play important roles in angiogenesis. They mediate cell-cell contact and cell adhesion to extracellular matrix. Roles of integrins have been described for a number of cell types. ECV304 endothelial cells were known to overexpress alpha3beta1 integrin and to form tube like structure in 3-D Matrigel culture. However the function of alpha3beta1 integrin in endothelial cells remains to be determined. Therefore, we have investigated morphological characteristics of ECV304 cells and roles of alpha3beta1 integrin in angiogenesis. To elucidate several characteristics, ECV304 endothelial cells were compared with HUVEC in the aspect of morphology, localization of integrins, angiogenesis pattern. In addition, role of alpha3beta1 integrin were analyzed in the aspect of endothelial cell binding, migration, invasion and tube formation on Matrigel. The result showed that alpha3beta1 integrin overexpressed ECV304 endothelial cells showed strong adhesiveness to extracellular matrix proteins, and high migration and invasion activities. Furthermore, expression of alpha3beta1 integrin was increased according to time course during in vitro culture and was continuously strong in ECV304 cells on 3-D Matrigel culture. These results indicate that alpha3beta1 integrin is able to be a critical component in control of angiogenesis by regulation of cell adhesion, migration, invasion and tube formation of ECV304 endothelial cells.