The Urokinase Receptor Takes Control of Cell Migration by Recruiting Integrins and FPR1 on the Cell Surface

Abstract

The receptor (uPAR) of the urokinase-type plasminogen activator (uPA) is crucial in cell migration since it concentrates uPA proteolytic activity at the cell surface, binds vitronectin and associates to integrins. uPAR cross-talk with receptors for the formylated peptide fMLF (fMLF-Rs) has been reported; however, cell-surface uPAR association to fMLF-Rs on the cell membrane has never been explored in detail.We now show that uPAR co-localizes at the cell-surface and co-immunoprecipitates with the high-affinity fMLF-R, FPR1, in uPAR-transfected HEK-293 (uPAR-293) cells. uPAR/β1 integrin and FPR1/β1 integrin co-localization was also observed. Serum or the WKYMVm peptide (W Pep), a FPR1 ligand, strongly increased all observed co-localizations in uPAR-293 cells, including FPR1/β1 integrin co-localization. By contrast, a low FPR1/β1 integrin co-localization was observed in uPAR-negative vector-transfected HEK-293 (V-293) cells, that was not increased by serum or W Pep stimulations.The role of uPAR interactions in cell migration was then explored. Both uPAR-293 and V-293 control cells efficiently migrated toward serum or purified EGF. However, cell treatments impairing uPAR interactions with fMLF-Rs or integrins, or inhibiting specific cell-signaling mediators abrogated uPAR-293 cell migration, without exerting any effect on V-293 control cells.Accordingly, uPAR depletion by a uPAR-targeting siRNA or uPAR blocking with an anti-uPAR polyclonal antibody in cells constitutively expressing high uPAR levels totally impaired their migration toward serum.Altogether, these results suggest that both uPAR-positive and uPAR-negative cells are able to migrate toward serum; however, uPAR expression renders cell migration totally and irreversibly uPAR-dependent, since it is completely inhibited by uPAR blocking.We propose that uPAR takes control of cell migration by recruiting fMLF-Rs and β1 integrins, thus promoting their co-localization at the cell-surface and driving pro-migratory signaling pathways.

Soluble urokinase plasminogen activator receptor as a prognostic marker of all-cause and cardiovascular mortality in a black population

“…Controversy still exists regarding the different mechanisms through which each of these markers plays a role in the pathology leading to cardiovascular mortality. It is known that the expression of uPAR by endothelial cells, macrophages and neutrophils substantially increases where organs undergo extensive tissue remodelling [41,42]. UPAR further relates to processes in the extracellular matrix [42], endothelial dysfunction [43], the development of atherosclerosis [44] and plaque rupture [45,46].…”

Extracellular Collagen Promotes Interleukin-1β–Induced Urokinase-Type Plasminogen Activator Production by Human Corneal Fibroblasts

“…[37][38][39] Corneal fibroblasts have previously been shown to express uPAR. 40 Binding of uPA to uPAR not only promotes proteolytic activity at the cell surface but also triggers intracellular signaling that is dependent on the FIGURE 9.…”

Upregulation of the N-Formyl Peptide Receptors in Scleroderma Fibroblasts Fosters the Switch to Myofibroblasts

“…Indeed, FPRs can be inactivated and/or desensitized by several mechanisms, depending on ligand engagement, activation of other chemotaxis receptors, internalization, or phosphorylation (11). In the presence of inactive FPRs, ATF-uPA is less efficient in inducing cell migration in SSc fibroblasts, but it is still able to stimulate cell proliferation to the same extent than normal fibroblasts, probably by activating other signaling partners, such as, for instance, integrins (52). Fibroblasts from lesional areas of SSc possess a motogenic phenotype and increased ability to produce type I collagen (56).…”