German cockroach extract activates protease-activated receptor 2 in human airway epithelial cells.
BACKGROUND
The German cockroach has been reported to act as an allergen that might be associated with a protease reaction in asthma. However, the molecular identities of the antigens in German cockroach extract (GCE) with protease activity and the protease-activated receptors (PARs) that are activated by GCE in human airway epithelial cells have not been characterized.


OBJECTIVE
We investigated the direct effect of GCE on Ca(2+) signaling in human airway epithelial cells and the type of PARs activated by GCE.


METHODS
The Ca(2+)-sensitive dye Fura2 was used to determine intracellular Ca(2+) concentration ([Ca(2+)](i)) by means of spectrofluorometry.


RESULTS
GCE induced a baseline type of [Ca(2+)](i) oscillations in a dose-dependent manner. The oscillations persisted for long periods of time in the absence of Ca(2+) entry across the plasma membrane, suggesting that the observed [Ca(2+)](i) increases were due to Ca(2+) release from intracellular stores. Accordingly, after depleting endoplasmic reticulum Ca(2+) with thapsigargin, an endoplasmic reticulum Ca(2+) ATPase inhibitor, the GCE-mediated [Ca(2+)](i) signals were abolished. Whereas desensitization of PAR-1, PAR-3, and PAR-4 had no effect on GCE-mediated Ca(2+) mobilization, no GCE-mediated [Ca(2+)](i) increase was observed after desensitization of PAR-2.


CONCLUSIONS
These results indicate that GCE has a direct effect on human airway epithelial cells, in particular generating [Ca(2+)](i) oscillations through Ca(2+) release from thapsigargin-sensitive Ca(2+) stores through activation of PAR-2.
Hong
Jeong Hee
JH
Department of Oral Biology, Oral Science Research Center, Brain Korea 21 Project for Medical Sciences, Yonsei University College of Dentistry, Seoul, Korea.
Lee
Syng-Ill
SI
Kim
Kyu-Earn
KE
Yong
Tai-Soon
TS
Seo
Jeong Taeg
JT
Sohn
Myung Hyun
MH
Shin
Dong Min
DM
D000485:Allergens / Q000276:immunology; D000818:Animals; D001980:Bronchi / Q000166:cytology / Q000276:immunology*; D020013:Calcium Signaling / Q000187:drug effects; D002460:Cell Line; D003058:Cockroaches / Q000201:enzymology / Q000276:immunology*; D010450:Endopeptidases / Q000276:immunology* / Q000494:pharmacology; D004847:Epithelial Cells / Q000276:immunology*; D006801:Humans; D044464:Receptor, PAR-2 / Q000378:metabolism*; D019284:Thapsigargin / Q000378:metabolism
D000485:Allergens; D044464:Receptor, PAR-2; D019284:Thapsigargin; D010450:Endopeptidases