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Protease activated receptor‐2 (PAR‐2) in the airway epithelium: a sentinel receptor triggered by the asthma associated allergen Alternaria alternata
Author(s) -
Flynn Andrea N,
Vagner Josef,
Schulz Stephanie,
Hoffman Justin,
Boitano Scott
Publication year - 2010
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.24.1_supplement.612.2
Subject(s) - alternaria , serine protease , protease , alternaria alternata , chemistry , respiratory epithelium , receptor , allergen , microbiology and biotechnology , biochemistry , immunology , biology , epithelium , allergy , enzyme , botany , genetics
In semi‐arid regions allergic asthma is strongly associated with the ubiquitous fungus Alternaria alternata . Similar to other allergens that trigger asthma, Alternaria has protease activity that can directly cleave and activate the G‐protein coupled receptor PAR‐2 in the airway epithelium. Using ratiometric Ca 2+ imaging, we found Alternaria filtrate (3.52 μg/ml protein; 0.58 μg/ml protease activity) lead to a rapid increase in intracellular Ca 2+ concentration ([Ca 2+ ] i ) in a human bronchial epithelial cell line. Consistent with PAR‐2 activation, Alternaria ‐dependent [Ca 2+ ] i changes were ablated by heat inactivation of the filtrate or pretreatment with serine‐specific protease inhibitors. While Alternaria filtrate did not activate HeLa cells with minimal PAR‐2 expression, HeLa cells transfected with PAR‐2 responded to Alternaria by increasing [Ca 2+ ] i . PAR‐2 can also be activated without proteolytic cleavage by small peptides (e.g., SLIGRL) and peptidomimetic compounds (e.g., 2‐furoyl‐LIGRL). We have developed two novel peptidomimetic compounds; a DTPA/Europium‐tagged ligand that allows for direct biochemical analysis of PAR‐2, and an LIGRL‐based compound that is predicted to improve in vivo stability. Further investigation of these and other novel ligands is central to understanding the role of PAR‐2 and may aid the development of treatments for allergic asthma.