Genetic variant in 3′ untranslated region of the mouse pycard gene regulates inflammasome activity

Quantitative trait locus mapping for interleukin-1 beta release after inflammasome priming and activation was performed on bone-marrow-derived macrophages (BMDM) from an AKRxDBA/2 mouse strain intercross. The strongest associated locus mapped very close to the Pycard gene on chromosome 7, which codes for the inflammasome adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC). The DBA/2 and AKR Pycard genes only differ at a single-nucleotide polymorphism (SNP) in their 3' untranslated region (UTR). DBA/2 vs. AKR BMDM had increased levels of Pycard mRNA expression and ASC protein, and increased inflammasome speck formation, which was associated with increased Pycard mRNA stability without an increased transcription rate. CRISPR/Cas9 gene editing was performed on DBA/2 embryonic stem cells to change the Pycard 3'UTR SNP from the DBA/2 to the AKR allele. This single base change significantly reduced Pycard expression and inflammasome activity after cells were differentiated into macrophages due to reduced Pycard mRNA stability.

Automated summary

The study identified a single-nucleotide polymorphism in the 3' untranslated region of the Pycard gene in DBA/2 and AKR mice, leading to differences in inflammasome activity. Using CRISPR/Cas9 gene editing, the researchers changed the Pycard gene from the DBA/2 to the AKR allele, resulting in reduced inflammasome activity.