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Cytoplasmic flagellin activates caspase-1 and secretion of interleukin 1β via Ipaf

Cytoplasmic flagellin activates caspase-1 and secretion of interleukin 1β via Ipaf Macrophages respond to Salmonella typhimurium infection via Ipaf, a NACHT–leucine-rich repeat family member that activates caspase-1 and secretion of interleukin 1β. However, the specific microbial salmonella-derived agonist responsible for activating Ipaf is unknown. We show here that cytosolic bacterial flagellin activated caspase-1 through Ipaf but was independent of Toll-like receptor 5, a known flagellin sensor. Stimulation of the Ipaf pathway in macrophages after infection required a functional salmonella pathogenicity island 1 type III secretion system but not the flagellar type III secretion system; furthermore, Ipaf activation could be recapitulated by the introduction of purified flagellin directly into the cytoplasm. These observations raise the possibility that the salmonella pathogenicity island 1 type III secretion system cannot completely exclude 'promiscuous' secretion of flagellin and that the host capitalizes on this 'error' by activating a potent host-defense pathway. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Nature Immunology Springer Journals

Cytoplasmic flagellin activates caspase-1 and secretion of interleukin 1β via Ipaf

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References (47)

Publisher
Springer Journals
Copyright
Copyright © 2006 by Nature Publishing Group
Subject
Biomedicine; Biomedicine, general; Immunology; Infectious Diseases
ISSN
1529-2908
eISSN
1529-2916
DOI
10.1038/ni1344
Publisher site
See Article on Publisher Site

Abstract

Macrophages respond to Salmonella typhimurium infection via Ipaf, a NACHT–leucine-rich repeat family member that activates caspase-1 and secretion of interleukin 1β. However, the specific microbial salmonella-derived agonist responsible for activating Ipaf is unknown. We show here that cytosolic bacterial flagellin activated caspase-1 through Ipaf but was independent of Toll-like receptor 5, a known flagellin sensor. Stimulation of the Ipaf pathway in macrophages after infection required a functional salmonella pathogenicity island 1 type III secretion system but not the flagellar type III secretion system; furthermore, Ipaf activation could be recapitulated by the introduction of purified flagellin directly into the cytoplasm. These observations raise the possibility that the salmonella pathogenicity island 1 type III secretion system cannot completely exclude 'promiscuous' secretion of flagellin and that the host capitalizes on this 'error' by activating a potent host-defense pathway.

Journal

Nature ImmunologySpringer Journals

Published: Apr 30, 2006

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