Proteomic identification and characterization of secreted N-glycosylated NPC2 following cross-linking of the high-affinity receptor for IgE on mast cells

Authors

  • Ashutosh K. Pathak,

    Corresponding author
    1. Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K.
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    • Center for Infectious Disease Dynamics, Department of Biology, The Pennsylvania State University, 508 Mueller Laboratory, University Park, PA 16802, U.S.A.

  • Birgit A. Helm

    1. Krebs Institute for Biomolecular Research, Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, U.K.
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email akp13@psu.edu

Abstract

Allergen-mediated cross-linking of the high-affinity receptor for IgE on mast cells triggers the release of diverse preformed and de novo synthesized immunoregulatory mediators that further the allergic response. A proteomic screen applied to the detection of proteins secreted by the model rat mast cell line, RBL-2H3 (rat basophilic leukaemia, subline 2H3.1), led to the identification of the cholesterol-binding glycoprotein, NPC2/RE1 (Niemann–Pick Type C2/epididymal secretory protein 1). Glycosylated NPC2 is secreted early in response to an IgE-mediated stimulus and co-localizes with the lysosomal membrane marker, CD63. NPC2 belongs to the ML (MD-2-related lipid-recognition) protein family (155 members), which includes the Toll-like receptor co-factors, MD-1 and MD-2, and perhaps most interestingly, seven major house dust mite allergens of unknown function (including Der p 2 and Der f 2). Possible role(s) for the protein in the allergic response and future applications of this approach are discussed.

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