Title : N-linked glycosylation regulates human
proteinase-activated receptor-1 cell surface expression and disarming via neutrophil
proteinases and thermolysin
Abstract :
- Proteinase-activated receptor 1 ( PAR(1) ) induces activation of platelet and vascular cells after proteolytic cleavage of its extracellular N terminus by thrombin
- In pathological situations, other proteinases may be generated in the circulation and might modify the responses of PAR(1) by cleaving extracellular domains
- In this study, epitope-tagged wild-type human PAR(1) ( hPAR(1) ) and a panel of N-linked glycosylation-deficient mutant receptors were permanently expressed in epithelial cells (Kirsten murine sarcoma virus-transformed rat kidney cells and CHO cells)
- We have analyzed the role of N-linked glycosylation in regulating proteinase activation/disarming and cell global expression of hPAR(1)
- We reported for the first time that glycosylation in the N terminus of hPAR(1) downstream of the tethered ligand (especially Asn(75) ) governs receptor disarming to trypsin, thermolysin, and the neutrophil proteinases elastase and proteinase 3 but not cathepsin G
- In addition, hPAR(1) is heavily N-linked glycosylated and sialylated in epithelial cell lines, and glycosylation occurs at all five consensus sites, namely, Asn(35), Asn(62), Asn(75), Asn(250), and Asn(259)
- Removing these N-linked glycosylation sequons affected hPAR(1) cell surface expression to varying degrees, and N-linked glycosylation at extracellular loop 2 (especially Asn(250) ) of hPAR(1) is essential for optimal receptor cell surface expression and receptor stability