Format

Send to

Choose Destination
Microbes Infect. 2010 Feb;12(2):126-34. doi: 10.1016/j.micinf.2009.11.003. Epub 2009 Nov 17.

Regulation of apoptosis and anti-apoptosis signalling by Francisella tularensis.

Author information

1
Department of Microbiology and Parasitology, University of Rijeka, Medical Faculty, Brace Branchetta 20, 51000 Rijeka, Croatia. marina@medri.hr

Abstract

Francisella tularensis induces apoptosis within macrophages but the temporal and spatial modulation through activation of caspase-1, caspase-3, and the anti-apoptosis nuclear transcription factor B (NF-kappaB) is not known. Whether escape of the bacteria into the cytosol is sufficient and/or essential for activation of NF-kappaB is not known. Our results show that F. tularensis subsp. novicida induces sustained nuclear translocation of NF-kappaB at early time points after infection of human monocytes derived macrophages (hMDMs). The sustained nuclear translocation of NF-kappaB is defective in the iglC mutant that fails to escape into the cytosol of macrophages. Nuclear translocation of NF-kappaB by the wild type strain is abolished upon treatment with the NF-kappaB inhibitor caffein acid phenyl ester. While the wild type strain triggers caspase-3 and caspase-1 activation by 6 h post-infection the iglC mutant is defective in triggering both caspases. In hMDMs treated with the apoptosis-inducing agent, staurosporin, there is an induction of cell death in the iglC mutant-infected macrophages despite reduced frequency of caspase-1 and caspase-3 activity. The wt-infected macrophages are resistant to cell death-induced agent. We conclude that although caspase-1 and capsase-3 are triggered within F. tularensis-infected hMDMs during early stages of infection, cell death is delayed, which is correlated with simultaneous activation of NF-kappaB.

PMID:
19925880
PMCID:
PMC2819573
DOI:
10.1016/j.micinf.2009.11.003
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for Elsevier Science Icon for PubMed Central
Loading ...
Support Center