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Updated: Aug 29, 2026

Myeloid Innate Signaling Pathway Regulation by MALT1 Paracaspase Activity
Published on: January 7, 2019
Cutting edge: anthrax lethal toxin inhibits activation of IFN-regulatory factor 3 by lipopolysaccharide
Oanh Dang1, Lorena Navarro, Keith Anderson
1Department of Biology, Division of Biological Sciences and UCSD Cancer Center, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093.
Abstract:
IFN-regulatory factor 3 (IRF3) is known to participate in the transcriptional induction of chemokines and cytokines, including IFNs, as a result of viral or bacterial infection. In this study, we demonstrate that the LPS-mediated activation of IRF3 and subsequent induction of chemokine genes or IRF3-responsive reporter constructs are inhibited after exposure of human or murine macrophages to the Bacillus anthracis toxin lethal factor. The inhibitory effect is caused by interference with the activation of the stress-activated protein kinase, p38, due to a proteolytic cleavage of mitogen-activated protein kinase kinase 6, and can be overcome by the ectopic expression of a cleavage-resistant mutant of mitogen-activated protein kinase kinase 6 or a constitutively active IRF3. The lethal factor-mediated inhibition of IRF3 activation and subsequent cytokine production through bacterial membrane components offers Bacillus anthracis an efficient mechanism to evade the innate immune response.
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