Homotypic and Endothelial Cell Adhesions via N-Cadherin Determine Polarity and Regulate Migration of Vascular Smooth Muscle Cells

Abstract

Abstract-Migration of smooth muscle cells from the arterial media to the intima is central to several vascular pathologies including restenosis. This study demonstrates that, like directional migration of other cells, smooth muscle migration is accompanied by a dramatic, polarized reorganization of the cell cytoskeleton that is accompanied by activation of the Rho GTPase Cdc42 and inactivation of glycogen synthase kinase-3␤. We also show, for the first time, that signals generated at the posterior-lateral aspects of wound edge cells by the cell-cell adhesion molecule N-cadherin are required for polarization and rapid migration of vascular smooth muscle. Importantly, when a cohort of migrating smooth muscle cells encounter CHO cells or the A10 smooth muscle cell line, neither of which expresses N-cadherin, polarity is only slightly suppressed. However, when smooth muscle cells encounter stably transfected, N-cadherinexpressing A10 cells or (N-cadherin-expressing) vascular endothelium, they rapidly lose their polarized phenotype. The latter finding indicates that endothelial signaling to innermost smooth muscle cells via N-cadherin may be critical to normal vessel wall stability. We infer that asymmetrical distribution of N-cadherin is necessary for the establishment of cell polarity during migration and that N-cadherin ligation is highly effective in abrogating polarized migration. Finally, we showed that endothelial cell polarity does not depend on N-cadherin; therefore, this molecule may be an attractive target for therapies to prevent restenosis without suppressing endothelial repair and risking late thrombosis. Key Words: smooth muscle cell Ⅲ migration Ⅲ N-cadherin Ⅲ polarity Ⅲ restenosis D irectional migration of smooth muscle cells from the arterial media to the intima and their subsequent proliferation is critical to the pathogenesis of important vascular disorders including restenosis, atherosclerosis, and bypass graft failure. 1,2 Endothelial cell loss initiates this neointimal formation because it occurs, albeit more slowly, after very gentle procedures that achieve deendothelialization with minimal medial trauma, 3 whereas severe medial trauma that leaves the endothelium largely intact does not produce a neointima. 4 Consequently, the sequelae to endothelial loss have been extensively studied.Platelet activation after endothelial denudation and subsequent release of the chemotactic mitogen, platelet-derived growth factor (PDGF), are important in promoting inward migration of smooth muscle cells. 5 Accordingly, antiplatelet or anti-PDGF strategies slow neointimal formation in animal models; however, migration is not fully arrested, and these strategies have not proven to be of substantial clinical value. 6 Instead, recent improvements in restenosis outcomes that have resulted from use of drug-eluting stents for the treatment of coronary artery disease rely on release of antimitogenic agents. 7,8 A limitation to antimitogenic therapy is that it may contribute to late thrombosis after stenting by suppress...

N-cadherin expression level modulates integrin-mediated polarity and strongly impacts on the speed and directionality of glial cell migration

“…We have previously shown that, following wounding, Cdc42 is activated and recruited to the leading edge of migrating astrocytes in a wound-healing assay and that localized activity of Cdc42 plays a key role in astrocyte polarization and directed migration (Etienne-Manneville and Hall, 2001;Osmani et al, 2010;Osmani et al, 2006). In agreement with a recent study realized in smooth muscle cells, by using a blocking antibody against N-cadherin (Sabatini et al, 2008), we show here that intercellular contacts are required for the recruitment and activation of Cdc42 at the leading edge in response to the wound. Active Cdc42 induces the recruitment and activation of the Par6-PKCf polarity complex (EtienneManneville and Hall, 2001) and APC clustering at microtubule plus-ends (Etienne-Manneville and Hall, 2003).…”

Rear Polarization of the Microtubule-Organizing Center in Neointimal Smooth Muscle Cells Depends on PKCα, ARPC5, and RHAMM

“…PKC isoforms regulating polarity include atypical aPKC, 2 PKC␤, 3-5 PKC, 6 and PKC␦. 5 We have recently shown that the MTOC is oriented anterior of the nucleus (ie, front polarized) in migrating medial SMCs in vitro, 7 which is in accord with other studies of cells migrating in two-dimensional culture. 8 -14 Little is known about polarization of the MTOC in vivo, where cells migrate in three dimensions.…”

N-cadherin-mediated cell–cell adhesion promotes cell migration in a three-dimensional matrix

“…Similarly, during neural crest cell migration, N-cadherin-mediated cell-cell adhesion has been shown to suppress membrane extensions by inhibiting Rac1 activity, so that the protrusions develop from the contact free edge (Theveneau et al, 2010). In addition, N-cadherin-mediated cell-cell adhesion is required for cell polarization and directional migration of vascular smooth muscle cells (Sabatini et al, 2008). Therefore, this N-cadherin-mediated contact inhibition may be what distinguishes the roles of leader vs. follower cells during collective migration of N-cadherin expressing cells.…”