Mimicry of the regulatory role of urokinase in lamellipodia formation by introduction of a non-native interdomain disulfide bond in its receptor

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  • Henrik Gårdsvoll, Institut for Klinisk Medicin, Danmark
  • Magnus Kjærgaard
  • Benedikte Jacobsen, Afdeling III, Danmark
  • Mette Camilla Kriegbaum, Afdeling III, Danmark
  • Mingdong Huang
  • ,
  • Michael Ploug
The high-affinity interaction between the urokinase-type plasminogen activator (uPA) and its glycolipid-anchored receptor (uPAR) plays a regulatory role for both extravascular fibrinolysis and uPAR-mediated adhesion and migration on vitronectin-coated surfaces. We have recently proposed that the adhesive function of uPAR is allosterically regulated via a "tightening" of its three-domain structure elicited by uPA binding. To challenge this proposition, we redesigned the uPAR structure to limit its inherent conformational flexibility by covalently tethering domains DI and DIII via a non-natural interdomain disulfide bond (uPAR(H47C-N259C)). The corresponding soluble receptor has 1) a smaller hydrodynamic volume, 2) a higher content of secondary structure, and 3) unaltered binding kinetics towards uPA. Most importantly, the purified uPAR(H47C-N259C) also displays a gain in affinity for the somatomedin B domain of vitronectin compared with uPAR(wt), thus recapitulating the improved affinity that accompanies uPA-uPAR(wt) complex formation. This functional mimicry is, intriguingly, operational also in a cellular setting, where it controls lamellipodia formation in uPAR-transfected HEK293 cells adhering to vitronectin. In this respect, the engineered constraint in uPAR(H47C-N259C) thus bypasses the regulatory role of uPA binding, resulting in a constitutively active uPAR. In conclusion, our data argue for a biological relevance of the interdomain dynamics of the glycolipid-anchored uPAR on the cell surface.
TidsskriftJournal of Biological Chemistry
Sider (fra-til)43515-26
Antal sider12
StatusUdgivet - 16 dec. 2011
Eksternt udgivetJa

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