A cleavage-resistant urokinase plasminogen activator receptor exhibits dysregulated cell-surface clearance.
Urokinase plasminogen activator receptor (u-PAR) binds urokinase plasminogen activator (u-PA) and participates in plasminogen activation in addition to modulating several cellular processes such as adhesion, proliferation, and migration. u-PAR is susceptible to proteolysis by its cognate ligand and several other proteases. To elucidate the biological significance of receptor cleavage by u-PA, we engineered and expressed a two-chain urokinase plasminogen activator (tcu-PA) cleavage-resistant u-PAR (cr-u-PAR). This mutated receptor was similar to wild-type u-PAR in binding u-PA and initiating plasminogen activation. However, cr-u-PAR exhibited accelerated internalization and resurfacing due to direct association with the endocytic receptor alpha(2)-macroglobulin receptor/low density lipoprotein receptor-related protein in the absence of the enzyme x inhibitor complex of tcu-PA and plasminogen activator inhibitor-1 (tcu-PA.PAI-1). cr-u-PAR-expressing cells had enhanced migration compared with wild-type u-PAR-expressing cells, and cr-u-PAR was less sensitive to chymotrypsin cleavage as compared with wt u-PAR. Our studies suggest that these mutations in the linker region result in a rearrangement within the cr-u-PAR structure that makes it resemble its ligand-bound form. This constitutively active variant may mimic highly glycosylated cleavage-resistant u-PAR expressed in certain highly malignant cancer-cells.
Nieves
Evelyn C
EC
Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. ecnieves@gmail.com
Manchanda
Naveen
N
D002448:Cell Adhesion / Q000235:genetics; D002465:Cell Movement; D049109:Cell Proliferation; D015870:Gene Expression; D006801:Humans; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism; D017395:Plasminogen Activator Inhibitor 1 / Q000235:genetics / Q000378:metabolism; D011973:Receptors, LDL / Q000235:genetics / Q000378:metabolism; D055293:Receptors, Urokinase Plasminogen Activator / Q000235:genetics / Q000378:metabolism*; D020298:U937 Cells; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics / Q000378:metabolism*
D026503:Low Density Lipoprotein Receptor-Related Protein-1; D017395:Plasminogen Activator Inhibitor 1; D011973:Receptors, LDL; D055293:Receptors, Urokinase Plasminogen Activator; C051321:SERPINE1 protein, human; D014568:Urokinase-Type Plasminogen Activator