Differential Caveolin-1 Polarization in Endothelial Cells during Migration in Two and Three Dimensions

Abstract

Endothelial cell (EC) migration is a critical event during multiple physiological and pathological processes. ECs move in the plane of the endothelium to heal superficially injured blood vessels but migrate in three dimensions during angiogenesis. We herein investigate differences in these modes of movement focusing on caveolae and their defining protein caveolin-1. Using a novel approach for morphological analysis of transmigrating cells, we show that ECs exhibit a polarized distribution of caveolin-1 when traversing a filter pore. Strikingly, in these cells caveolin-1 seems to be released from caveolar structures in the cell rear and to relocalize at the cell front in a cytoplasmic form. In contrast, during planar movement caveolin-1 is concentrated at the rear of ECs, colocalizing with caveolae. The phosphorylatable Tyr14 residue of caveolin-1 is required for polarization of the protein during transmigration but does not alter polarization during planar movement. Palmitoylation of caveolin-1 is not essential for redistribution of the protein during either mode of movement. Thus, ECs migrating in three dimensions uniquely exhibit dissociation of caveolin-1 from caveolae and phosphorylation-dependent relocalization to the cell front.

Identification of a Novel Domain at the N Terminus of Caveolin-1 That Controls Rear Polarization of the Protein and Caveolae Formation

“…Consistent with previous observations (24,25), Cav 1-178 -GFP polarized at the rear of migrating Cav-1 Ϫ/Ϫ MEFs ( Fig. 2A, a), suggesting that exogenously expressed Cav-1 behaves as endogenous protein and is able to polarize in Cav-1-deficient cells.…”

“…Thus, at least in endothelium, caveolae may integrate signaling events with vesicular transport (44). We and others have shown that concomitant with Cav-1 polarization, caveolae move to cell posterior as well (24,25), suggesting that caveolae may function as transport cargos carrying Cav-1 to cell rear. To test whether aa 1-60 of Cav-1 affect caveolae formation and whether caveolae are depolarized in cells expressing the depolarization mutant, Cav-1…”

“…We and other groups have recently shown that Cav-1 was specifically polarizes to the posterior of migrating cells (22,24,25). In the present study, we systematically identified and characterized a domain at the N terminus of Cav-1 that controls rear polarization of the protein.…”

“…We and others have shown recently that caveolae and Cav-1 are polarized in migrating endothelial cells (11,24,25). However, the mechanism underlying the asymmetrical distribution is not known.…”

New Insights into 4-Amino-2-tri-fluoromethyl-phenyl Ester Inhibition of Cell Growth and Migration in the A549 Lung Adenocarcinoma Cell Line

“…However, it is still controversial about the expression and distribution of CAV1 in cell migration. CAV1 preferentially accumulates at the cell front in transmigrating endothelial cells and neurons, but at the rear of migrating fibroblasts neurons and endothelial cell (Parat et al, 2003;Sun et al, 2007;Lentini et al, 2008). Unlike for the cells we have mentioned, polarization and relocation to the trailing edge of CAV1 were not observed in migrating metastatic cells (Urra et al, 2012).…”