Abstract
Purpose: :
Integrins are a family of cell surface glycoproteins that mediate cell proliferation and differentiation and are thought to play an important role in PVR. This study evaluated the expression and localization of integrin α5β1 in human RPE and the effect of JSM6427, an Integrin α5β1 specific antagonist, on the modulation of human fetal RPE (hfRPE) cell attachment, proliferation, migration and F-actin cytoskeleton distribution.
Methods: :
Primary hfRPE cell cultures were obtained as described previously (Maminishkis et al., 2006, IOVS). Expression and localization of integrin α5β1 were analyzed by western blot and immunohistochemistry. Cell attachment assays were used to test the effect of integrin α5β1 antagonist JSM6427 as well as the inactive analogue JSM8009 on RPE attachment to different extracellular matrices. BrdU incorporation and wound healing assays were used to quantify the effects of JSM6427 on hfRPE proliferation and migration. Phalloidin staining was used to visualize the distribution of actin cytoskeleton. Cell viability was evaluated using a Live/Dead Viability/Cytotoxity kit.
Results: :
We demonstrate that the integrin α5β1 is present on both the native adult and cultured human fetal RPE. In cultured hfRPE, α5 subunit was detected mainly at the apical membrane while the β1 subunit was clearly detected at both the apical and basolateral membranes. Integrin α5β1 antagonist JSM6427 significantly inhibited hfRPE cell attachment on fibronectin while it had no effect on cell attachment on laminin, collagen I or IV. The inactive analogue JSM8009 had no significant effect on cell attachment. JSM6427 also showed strong inhibitory effects on bFGF and PDGF-BB induced cell migration and proliferation. Furthermore, JSM6427 induced significant disruption of the F-actin cytoskeleton of dividing RPE cells but not in quiescent cells.
Conclusions: :
The effects observed with the integrin α5β1 antagonist JSM6427 lead us to conclude that integrin α5β1 plays an important role in human RPE cell attachment, proliferation, and migration as well as in maintaining the F-actin cytoskeleton. The inhibitory effects of this antagonist on these functions suggest a potential clinical use of JSM6427 against proliferative retinopathies.
Keywords: retinal pigment epithelium • proliferative vitreoretinopathy • cytoskeleton