|
|
||||||||
Published online before print February 19, 2008
| ||||||||||||||||||||||||||||||||||||||||||||||||||||
Division of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University Graduate School of Medical Sciences, Tokyo, Japan
1Correspondence: Division of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University Graduate School of Medical Sciences, 30-1 Oyaguchikami-cho Itabashi-ku, Tokyo 173-8610, Japan. E-mail: ysuzuki{at}med.nihon-u.ac.jp
NO is known to suppress mast cell activation, but the role of NO in mast cell survival is unclear. Ligation of the high-affinity receptor for IgE (Fc
RI) resulted in NO production in mast cells within minutes. This NO production was largely dependent on NO synthase (NOS) activity and extracellular Ca2+. The NO production required an aggregation of Fc
RI and was accompanied by increased phosphorylation of endothelial NOS (eNOS) at Ser1177 and Akt at Ser473. The phosphorylation of eNOS and Akt and the production of NO were abolished by the PI-3K inhibitor wortmannin. Although thapsigargin (TG) induced NO production as well, this response occurred with a considerable lag time (>10 min) and was independent of Fc
RI aggregation and PI-3K and NOS activity. Mast cells underwent apoptosis in response to TG but not upon Fc
RI ligation. However, when the NOS-dependent NO production was blocked, Fc
RI ligation caused sizable apoptosis, substantial mitochondrial cytochrome c release, caspase-3/7 activation, and collapse of the mitochondrial membrane potential, all of which were inhibited by the caspase-3 inhibitor z-Asp-Glu-Val-Asp-fluoromethylketone. The data suggest that the NO produced by the PI-3K-Akt-eNOS pathway is involved in protecting mast cells from cell death.
Key Words: antigen eNOS apoptosis cell survival
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |