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Evaluation of Caspase Activation to Assess Innate Immune Cell Death
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ASC-mediated NF-kappaB activation leading to interleukin-8 production requires caspase-8 and is inhibited by CLARP

Mizuho Hasegawa1, Ryu Imamura, Takeshi Kinoshita

  • 1Center for the Development of Molecular Target Drugs, Cancer Research Institute, Kanazawa University, 13-1 Takaramachi, Kanazawa, Ishikawa 920-0934, Japan.

The Journal of Biological Chemistry
|February 11, 2005
PubMed

Insights

Apoptosis and inflammation signaling adaptor ASC activates NF-kappaB via caspase-8. This pathway, triggered by bacterial components, leads to the production of interleukin-8, demonstrating its physiological relevance.

Area of Science:

  • Immunology
  • Cell Biology
  • Molecular Signaling

Background:

  • ASC (apoptosis-associated speck-like protein containing a CARD) is a key adaptor molecule.
  • It mediates inflammatory and apoptotic signals from Apaf-1-like molecules, including CARD12/Ipaf and cryopyrin.
  • Understanding ASC's signaling pathway is crucial for comprehending innate immune responses.

Purpose of the Study:

  • To elucidate the signaling pathway mediated by ASC.
  • To investigate the role of caspase-8 in ASC-induced NF-kappaB activation.
  • To determine the physiological relevance of ASC-mediated signaling.

Main Methods:

  • Established cell lines for studying ASC-mediated signaling.
  • Utilized muramyl dipeptide to trigger Nod2 and CARD12 interaction with ASC.
  • Assessed NF-kappaB activation, caspase-8 requirement, and interleukin-8 production.

Main Results:

  • Muramyl dipeptide induced ASC-mediated NF-kappaB activation requiring caspase-8.
  • Caspase-8 catalytic activity was essential for NF-kappaB activation at endogenous levels.
  • ASC recruited caspase-8 and CLARP to speck-like aggregates, but not FADD or Nod2.
  • Interleukin-8 production was observed in response to muramyl dipeptide.

Conclusions:

  • Caspase-8 plays a critical role in ASC-mediated NF-kappaB activation.
  • ASC-mediated NF-kappaB activation leads to physiologically relevant gene expression, such as interleukin-8 production.
  • This study clarifies a significant pathway in innate immunity and inflammation signaling.

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