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Modeling the TNFα-Induced Apoptosis Pathway in Hepatocytes

Abstract:

The proinflammatory cytokine TNFα fails to provoke cell death in isolated hepatocytes but has been implicated in hepatocyte apoptosis during liver diseases associated with chronic inflammation. Recently, we showed that TNFα is able to sensitize primary murine hepatocytes cultured on collagen to Fas ligand-induced apoptosis and presented a mathematical model of the sensitizing effect. Here, we analyze how TNFα induces apoptosis in combination with the transcriptional inhibitor actinomycin D (ActD). Accumulation of reactive oxygen species (ROS) in response to TNFR activation turns out to be critical for sustained activation of JNK which then triggers mitochondrial pathway-dependent apoptosis. In addition, the amount of JNK is strongly upregulated in a ROS-dependent way. In contrast to TNFα plus cycloheximide no cFLIP degradation is observed suggesting a different apoptosis pathway in which the Itch-mediated cFLIP degradation and predominantly caspase-8 activation is not involved. Time-resolved data of the respective pro- and antiapoptotic factors are obtained and subjected to mathematical modeling. On the basis of these data we developed a mathematical model which reproduces the complex interplay regulating the phosphorylation status of JNK and generation of ROS. This model was fully integrated with our model of TNFα/Fas ligand sensitizing as well as with a published NF-κB-model. The resulting comprehensive model delivers insight in the dynamical interplay between the TNFα and FasL pathways, NF-κB and ROS and gives an example for successful model integration.

21533085

Projects: A2.2: Regulation of pro-apoptotic and anti-apoptotic responses in hepato...

PLoS ONE
PLoS ONE 6(4): e18646
7th Oct 2010

Rebekka Schlatter, Kathrin Schmich, Anna Lutz, Judith Trefzger, Oliver Sawodny, Michael Ederer, Irmgard Merfort

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[Anna Lutz] [Oliver Sawodny] [Michael Ederer] [Irmgard Merfort]

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Cell
Views: 1986
  • Created: 12th May 2011 at 15:13
  • Last updated: 24th Oct 2013 at 16:19

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