Document Detail


Caspase-3 feeds back on caspase-8, Bid and XIAP in type I Fas signaling in primary mouse hepatocytes.
MedLine Citation:
PMID:  22246639     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
The TNF-R1 like receptor Fas is highly expressed on the plasma membrane of hepatocytes and plays an essential role in liver homeostasis. We recently showed that in collagen-cultured primary mouse hepatocytes, Fas stimulation triggers apoptosis via the so-called type I extrinsic signaling pathway. Central to this pathway is the direct caspase-8-mediated cleavage and activation of caspase-3 as compared to the type II pathway which first requires caspase-8-mediated Bid cleavage to trigger mitochondrial cytochrome c release for caspase-3 activation. Mathematical modeling can be used to understand complex signaling systems such as crosstalks and feedback or feedforward loops. A previously published model predicted a positive feedback loop between active caspases-3 and -8 in both type I and type II FasL signaling in lymphocytes and Hela cells, respectively. Here we experimentally tested this hypothesis in our hepatocytic type I Fas signaling pathway by using wild-type and XIAP-deficient primary hepatocytes and two recently characterized, selective caspase-3/-7 inhibitors (AB06 and AB13). Caspase-3/-7 activity assays and quantitative western blotting confirmed that fully processed, active p17 caspase-3 feeds back on caspase-8 by cleaving its partially processed p43 form into the fully processed p18 species. Our data do not discriminate if p18 positively or negatively influences FasL-induced apoptosis or is responsible for non-apoptotic aspects of FasL signaling. However, we found that caspase-3 also feeds back on Bid and degrades its own inhibitor XIAP, both events that may enhance caspase-3 activity and apoptosis. Thus, potent, selective caspase-3 inhibitors are useful tools to understand complex signaling circuitries in apoptosis.
Authors:
Karine Sá Ferreira; Clemens Kreutz; Sabine Macnelly; Karin Neubert; Angelika Haber; Matthew Bogyo; Jens Timmer; Christoph Borner
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-13
Journal Detail:
Title:  Apoptosis : an international journal on programmed cell death     Volume:  -     ISSN:  1573-675X     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9712129     Medline TA:  Apoptosis     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Institute of Molecular Medicine and Cell Research, University of Freiburg, Stefan-Meier-Str. 17, 79104, Freiburg, Germany.
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