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Differential Cell Binding Of Intact (HK) And Cleaved (HKa) High Molecular Weight Kininogen Is Mediated By The Presence Of Urokinase Receptor, uPAR (CD87)
Author(s) -
Pixley Robin A.,
Liu Yuchuan,
Espinola Ricardo G,
Colman Robert W
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.357.7
Subject(s) - urokinase receptor , receptor , high molecular weight kininogen , microbiology and biotechnology , supar , biology , chemistry , kininogen , biochemistry , bradykinin
The patho‐physiologic activation of the plasma kallikrein‐kinin system requires the proteolysis and assembly of receptors on the cell membrane. HK binds to endothelial cells through an interaction with a multi‐protein receptor complex that consists of: uPAR, globular C1q receptor (gC1qR, p33) and cytokeratin 1 (CK1). In a preliminary report (Blood 106, 748a, 2005, Abst 2666), we measured the direct binding of HK & HKa to suPAR (soluble uPAR), gC1qR and CK1 using surface plasmon resonance. The binding of HK and HKa to all of receptors was zinc dependent. The affinity for HK & HKa was gC1qR>CK1>suPAR. The high affinity for gC1qR and CK1 was similar for HK & HKa. However, binding of HKa compared to HK was 2.5‐fold tighter for CK1, but 50‐fold tighter for suPAR. Although suPAR has the weakest affinity of the three receptors, it distinguishes between HK & HKa. We hypothesized that there would be differential binding of HK and HKa to cells lacking the uPAR receptor. Human Embryonic Kidney 293 cells (HEK) lack the uPAR receptor. We compared the differential binding of HK and HKa to non‐ and uPAR‐ transfected (uHEK) cells. With zinc there was more binding of labeled HKa than HK to both types. At HKa concentrations >100 nM, there was additional HKa binding to uHEK. We attribute this to the low affinity binding sites of uPAR for HKa. These results suggest that HK and HKa may play different roles in cell interactions on membranes. 5R01CA83121.