The urokinase receptor takes control of cell migration by recruiting integrins and FPR1 on the cell surface.
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.
Department of Chemistry and Biology, University of Salerno, Salerno, Italy.
Anna
A
Gorrasi
Department of Chemistry and Biology, University of Salerno, Salerno, Italy.
Anna
A
Li Santi
Department of Medicine and Surgery, University of Salerno, Salerno, Italy.
Giuseppina
G
Amodio
Department of Chemistry and Biology, University of Salerno, Salerno, Italy.
Daniela
D
Alfano
Department of Medicine and Surgery, University of Salerno, Salerno, Italy.
Paolo
P
Remondelli
Department of Translational Medical Sciences, "Federico II" University, Naples, Italy.
Nunzia
N
Montuori
Department of Chemistry and Biology, University of Salerno, Salerno, Italy.
Pia
P
Ragno
D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002465:Cell Movement / Q000502:physiology*; D057809:HEK293 Cells; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D008024:Ligands; D009842:Oligopeptides / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism*; D044042:Receptors, Formyl Peptide / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
C469986:FPR1 protein, human; D019012:Integrin beta1; D008024:Ligands; D009842:Oligopeptides; D011956:Receptors, Cell Surface; D044042:Receptors, Formyl Peptide; D055293:Receptors, Urokinase Plasminogen Activator; C113617:Trp-Lys-Tyr-Met-Val-Met