Urokinase-type plasminogen activator receptor (uPAR) (uPAR)

The urokinase-type plasminogen activator receptor (uPAR) is a glycosylphosphatidylinositol (GPI)-anchored membrane protein that serves as a critical scaffold for localized proteolysis and cell signaling. On mesenchymal stem cells (MSCs), uPAR binds its ligand, urokinase-type plasminogen activator (uPA), which subsequently recruits and activates plasminogen into the active protease plasmin (PMID: 22431261). This localized proteolytic cascade is essential for MSC migration and homing to sites of injury or tumor microenvironments by facilitating the degradation of the extracellular matrix and basement membranes (PMID: 17068487). Beyond its role in proteolysis, the uPA•uPAR complex acts as a signaling hub by interacting with co-receptors such as integrins and vitronectin to activate intracellular pathways like MAPK/ERK and PI3K/Akt, which regulate cell survival and proliferation (UniProt: Q03405). In pathological contexts, particularly in oncology, the over-expression of uPAR is strongly associated with increased tumor invasiveness, metastasis, and poor prognosis, making it a significant target for therapeutic antibodies and small molecule inhibitors (PubMed: 25653301). Therapeutic strategies often aim to disrupt the uPA-uPAR interaction or inhibit the enzymatic activity of the complex to prevent the downstream activation of plasminogen and subsequent tissue degradation.

Other names

PLAURCD87U-PARMonocyte activation antigen Mo3Plasminogen activator, urokinase receptor

Inhibition of uPA binding to uPAR, competitive antagonism of the uPAR-integrin interaction, and inhibition of the catalytic activity of uPAR-bound uPA to prevent plasminogen activation.