title: Regulation of P-selectin binding to the neutrophil P-selectin counter-receptor P-selectin glycoprotein ligand-1 by neutrophil elastase and cathepsin G.
abstract: In the inflammatory response, leukocyte rolling before adhesion and transmigration through the blood vessel wall is mediated by specific cell surface adhesion receptors. Neutrophil rolling involves the interaction of P-selectin expressed on activated endothelium and its counter-receptor on neutrophils, P-selectin glycoprotein ligand-1 (PSGL-1). Here, it is reported that P-selectin binding to neutrophils is lost under conditions that cause the release of proteinases from neutrophil primary granules. Treatment of neutrophils with the purified neutrophil granule proteinases, cathepsin G and elastase, rapidly abolished their capacity to bind P-selectin. This inactivation corresponded to loss of the N-terminal domain of PSGL-1, as assessed by Western blot analysis. A loss of intact PSGL-1 protein from the surfaces of neutrophils after the induction of degranulation was also detected by Western blot analysis. Cathepsin G initially cleaved near the PSGL-1 N-terminus, whereas neutrophil elastase predominantly cleaved at a more C-terminal site within the protein mucin core. Consistent with this, cathepsin G cleaved a synthetic peptide based on the PSGL-1 N-terminus between Tyr-7/Leu-8. Under conditions producing neutrophil degranulation in incubations containing mixtures of platelets and neutrophils, the loss of PSGL-1, but not P-selectin, from platelet-neutrophil lysates was detected. Cathepsin G- or neutrophil elastase-mediated PSGL-1 proteolysis may constitute a potential autocrine mechanism for down-regulation of neutrophil adhesion to P-selectin.
authors.affiliation: Hazel and Pip Appel Vascular Biology Laboratory, Baker Medical Research Institute, Melbourne, Australia.
authors.forename: E E
authors.initials: EE
authors.lastname: Gardiner
authors.forename: M
authors.initials: M
authors.lastname: De Luca
authors.forename: T
authors.initials: T
authors.lastname: McNally
authors.forename: A D
authors.initials: AD
authors.lastname: Michelson
authors.forename: R K
authors.initials: RK
authors.lastname: Andrews
authors.forename: M C
authors.initials: MC
authors.lastname: Berndt
mesh_terms: D000595:Amino Acid Sequence; D019898:Autocrine Communication; D056649:Cathepsin G; D002403:Cathepsins / Q000502:physiology*; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D019272:Leukocyte Elastase / Q000502:physiology*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000494:pharmacology; D008969:Molecular Sequence Data; D009504:Neutrophils / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D019007:P-Selectin / Q000378:metabolism*; D019038:Platelet Glycoprotein GPIb-IX Complex / Q000737:chemistry; D011485:Protein Binding; D012697:Serine Endopeptidases
chemical_list: D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein; D019038:Platelet Glycoprotein GPIb-IX Complex; D002403:Cathepsins; D012697:Serine Endopeptidases; C534094:CTSG protein, human; D056649:Cathepsin G; D019272:Leukocyte Elastase; D008666:Metalloendopeptidases; C099092:mocarhagin