Complement receptor Mac-1 is an adaptor for NB1 (CD177)-mediated PR3-ANCA neutrophil activation

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Item Type:	Article
Title:	Complement receptor Mac-1 is an adaptor for NB1 (CD177)-mediated PR3-ANCA neutrophil activation
Creators Name:	Jerke, U., Rolle, S., Dittmar, G., Bayat, B., Santoso, S., Sporbert, A., Luft, F.C. and Kettritz, R.
Abstract:	The glycosylphosphatidylinositol (GPI)-anchored neutrophil-specific receptor NB1 (CD177) presents the autoantigen proteinase 3 (PR3) on the membrane of a neutrophil subset. PR3-ANCA-activated neutrophils participate in small-vessel vasculitis. Since NB1 lacks an intracellular domain, we characterized components of the NB1 signaling complex that are pivotal for neutrophil activation. PR3-ANCA resulted in degranulation and superoxide production in the mNB1pos/PR3high neutrophils, but not in the mNB1neg/PR3low subset, whereas MPO-ANCA and fMLP caused similar responses. The NB1 signaling complex that was precipitated from plasma membranes contained the transmembrane receptor Mac-1 (CD11b/CD18) as shown by MS/MS analysis and immunoblotting. NB1 co-precipitation was less for CD11a and not detectable for CD11c. NB1 showed direct protein-protein interactions with both CD11b and CD11a by surface plasmon resonance analysis (SPR). However, when these integrins were presented as heterodimeric transmembrane proteins on transfected cells, only CD11b/CD18 (Mac-1) transfected cells adhered to immobilized NB1 protein. This adhesion was inhibited by mab against NB1, CD11b and CD18. NB1, PR3 and Mac-1 were located within lipid rafts. In addition, confocal microscopy showed the strongest NB1 co-localization with CD11b and CD18 on the neutrophil. Stimulation with NB1-activating mab triggered degranulation and superoxide production in mNB1pos/mPR3high neutrophils and this effect was reduced using blocking antibodies to CD11b. CD11b blockade also inhibited PR3-ANCA-induced neutrophil activation, even when beta2-integrin ligand-dependent signals were omitted. We establish the pivotal role of the NB1-Mac-1 receptor interaction for PR3-ANCA-mediated neutrophil activation.
Keywords:	Glycosyl Phosphatidyl Inositol Anchors, Integrin, Neutrophil, Signal Transduction, Superoxide Ion
Source:	Journal of Biological Chemistry
ISSN:	0021-9258
Publisher:	American Society for Biochemistry and Molecular Biology
Volume:	286
Number:	9
Page Range:	7070-7081
Date:	4 March 2011
Official Publication:	https://doi.org/10.1074/jbc.M110.171256
PubMed:	View item in PubMed

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