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Updated: Aug 9, 2026
Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages
Published on: May 21, 2018
A genotype-first approach reveals the molecular basis of pyrin inflammasome activation
Naoya Iwata1, Yoshihiko Kuchitsu2, Atsushi Hijikata3
1Department of Pediatrics, Kyoto University Graduate School of Medicine, Kyoto, Japan.
Abstract:
Mutations in the MEFV gene, which encodes pyrin, are associated with a spectrum of inflammatory conditions called pyrin-associated autoinflammatory diseases (PAADs). Of the 400 MEFV variants listed in the Infevers database, most are classified as variants of uncertain significance. Thus, genetic diagnosis of PAADs remains challenging, and the molecular mechanisms underlying pyrin activation remain poorly understood. Here, we used a cell-based pyroptosis assay to stratify 265 missense MEFV variants and identified previously uncharacterized pathogenic variants. We then characterized the interaction between the pyrin B30.2 domain and CDC42, a key regulator of pyrin intracellular trafficking and activation. We found that classical familial Mediterranean fever (FMF)-related variants bind tightly to CDC42 to induce pyrin hyperactivation, whereas certain non-FMF variants induce pyrin hyperactivation independently of CDC42, indicating involvement of multiple pathways in pyrin activation. Our approach provides a proof of concept for a genotype-first approach, which may advance our understanding of complex human diseases.
Insights
Genetic diagnosis of pyrin-associated autoinflammatory diseases (PAADs) is challenging due to many uncertain MEFV variants. This study identifies pathogenic variants and reveals distinct pathways for pyrin activation, advancing disease understanding.
Area of Science:
- Genetics
- Immunology
- Molecular Biology
Background:
- Pyrin-associated autoinflammatory diseases (PAADs) are linked to MEFV gene mutations, but most variants have uncertain significance, complicating diagnosis.
- The molecular mechanisms of pyrin activation in PAADs are not fully understood.
- Accurate genetic diagnosis and mechanistic insights are crucial for understanding and treating these inflammatory conditions.
Purpose of the Study:
- To stratify MEFV variants using a pyroptosis assay and identify novel pathogenic variants.
- To investigate the interaction between the pyrin B30.2 domain and CDC42 in pyrin activation.
- To elucidate the distinct molecular pathways involved in pyrin activation by different MEFV variants.
Main Methods:
- Utilized a cell-based pyroptosis assay to functionally characterize 265 missense MEFV variants.
- Investigated the interaction between pyrin's B30.2 domain and CDC42.
- Stratified variants based on their impact on pyrin activation and interaction with CDC42.
Main Results:
- Identified previously uncharacterized pathogenic MEFV variants.
- Demonstrated that familial Mediterranean fever (FMF)-related variants bind tightly to CDC42, causing pyrin hyperactivation.
- Showed that non-FMF variants can hyperactivate pyrin independently of CDC42, suggesting multiple activation pathways.
Conclusions:
- A functional pyroptosis assay can effectively stratify MEFV variants and identify pathogenic mutations.
- Pyrin activation involves at least two distinct pathways: one dependent on CDC42 and another independent of it.
- A genotype-first approach holds promise for advancing the understanding of PAADs and other complex genetic diseases.
