An uncleavable uPAR mutant allows dissection of signaling pathways in uPA-dependent cell migration.
Urokinase-type plasminogen activator (uPA) binding to uPAR induces migration, adhesion, and proliferation through multiple interactions with G proteins-coupled receptor FPRL1, integrins, or the epidermal growth factor (EGF) receptor (EGFR). At least two forms of uPAR are present on the cell surface: full-length and cleaved uPAR, each specifically interacting with one or more transmembrane proteins. The connection between these interactions and the effects on the signaling pathways activation is not clear. We have exploited an uPAR mutant (hcr, human cleavage resistant) to dissect the pathways involved in uPA-induced cell migration. This mutant is not cleaved by proteases, is glycosylphosphatidylinositol anchored, and binds uPA with a normal K(d). Both wild-type (wt) and hcr-uPAR are able to mediate uPA-induced migration, are constitutively associated with the EGFR, and associate with alpha3beta1 integrin upon uPA binding. However, they engage different pathways in response to uPA. wt-uPAR requires both integrins and FPRL1 to mediate uPA-induced migration, and association of wt-uPAR to alpha3beta1 results in uPAR cleavage and extracellular signal-regulated kinase (ERK) activation. On the contrary, hcr-uPAR does not activate ERK and does not engage FPRL1 or any other G protein-coupled receptor, but it activates an alternative pathway initiated by the formation of a triple complex (uPAR-alpha3beta1-EGFR) and resulting in the autotyrosine phosphorylation of EGFR.
Mazzieri
Roberta
R
Department of Molecular Biology and Functional Genomics, Università Vita Salute San Raffaele and S. Raffaele Scientific Institute, 20132 Milan, Italy.
D'Alessio
Silvia
S
Kenmoe
Richard Kamgang
RK
Ossowski
Liliana
L
Blasi
Francesco
F
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D002465:Cell Movement / Q000187:drug effects*; D004789:Enzyme Activation; D066246:ErbB Receptors / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D010447:Peptide Hydrolases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D055293:Receptors, Urokinase Plasminogen Activator; D015398:Signal Transduction / Q000187:drug effects*; D013997:Time Factors; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism / Q000494:pharmacology*
D016023:Integrins; C524898:PLAUR protein, human; C524899:Plaur protein, mouse; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D066246:ErbB Receptors; D048049:Extracellular Signal-Regulated MAP Kinases; D010447:Peptide Hydrolases; D014568:Urokinase-Type Plasminogen Activator