Identification of CARDIAK, a RIP-like kinase that associates with caspase-1

Area of Science:

• Cellular signaling pathways
• Molecular biology
• Immunology

Background:

• Tumor necrosis factor receptor (TNFR) superfamily members regulate cell growth, differentiation, and death.
• TNFR-1 signaling involves adaptor proteins like TRADD and RIP, mediating NF-kappa B activation.
• RIP interacts with caspase-2 via RAIDD, highlighting the role of death domains (DD) and caspase-recruiting domains (CARD).

Purpose of the Study:

• To identify and characterize a novel RIP-like kinase involved in TNFR signaling.
• To elucidate the role of this new kinase in NF-kappa B and JNK activation.
• To investigate the kinase's involvement in caspase-1 activation and IL-1 beta production.

Main Methods:

• Identification and cloning of a novel RIP-like kinase, CARDIAK.
• Overexpression studies to assess CARDIAK's effect on NF-kappa B and JNK activation.
• Co-immunoprecipitation assays to study interactions with TRAF-1, TRAF-2, and caspase-1.
• Analysis of caspase-1 processing and activation.

Main Results:

• A novel kinase, CARDIAK, containing a kinase domain and a CARD, was identified.
• Overexpression of CARDIAK led to activation of NF-kappa B and Jun N-terminal kinase (JNK).
• CARDIAK interacts with TRAF-1 and TRAF-2, and its NF-kappa B activation is TRAF-2 dependent.
• CARDIAK specifically interacts with caspase-1 (ICE), promoting its processing and activation.

Conclusions:

• CARDIAK is a novel kinase that plays a role in NF-kappa B and JNK signaling pathways.
• CARDIAK contributes to the production of the proinflammatory cytokine IL-1 beta via caspase-1 activation.
• The findings suggest CARDIAK as a potential target for modulating inflammatory responses.