PYCARD Gene: Function, Inflammasome Role, and Disease Associations | Biomedical Resource

The PYCARD gene encodes the apoptosis-associated speck-like protein containing a CARD (ASC), a 22 kDa adaptor protein composed of an N-terminal pyrin domain (PYD) and a C-terminal caspase recruitment domain (CARD). ASC is a key component of the inflammasome, a multiprotein complex that activates caspase-1, leading to the maturation of pro-inflammatory cytokines IL-1β and IL-18 and the induction of pyroptosis. ASC functions as a bridge between pattern recognition receptors (e.g., NLRP3, AIM2) and caspase-1, promoting the assembly of the inflammasome complex. It is also involved in NF-κB signaling and apoptosis. Aberrant ASC expression or mutations are linked to autoinflammatory diseases, infectious diseases, and cancer.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• NOD-like receptor signaling pathway

• Cytosolic DNA-sensing pathway

• IL-1 family signaling

• Pyroptosis

• Apoptosis

• Inflammasome pathway

The ASC protein (encoded by PYCARD) is a bipartite adaptor composed of an N-terminal pyrin domain (PYD) and a C-terminal caspase recruitment domain (CARD). It serves as a critical scaffold in inflammasome complexes, linking upstream sensors (e.g., NLRP3, AIM2) to pro-caspase-1. Upon activation, ASC polymerizes into large speck-like aggregates, facilitating proximity-induced autocleavage of pro-caspase-1 to active caspase-1, which then cleaves pro-IL-1β and pro-IL-18 into their mature forms and induces pyroptosis. ASC also participates in NF-κB activation and apoptosis. Its expression is regulated by promoter methylation, and loss of ASC is frequently observed in cancers, contributing to tumor progression. In the central nervous system, ASC specks may act as danger-associated molecular patterns, promoting neuroinflammation in Alzheimer's disease.