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Updated: Jun 8, 2025
Evaluation of Caspase Activation to Assess Innate Immune Cell Death
Published on: January 20, 2023
Paralichthys olivaceus GSDME-mediated pyroptosis is regulated by multiple caspases in different manners
Kangwei Hao1, Liming Yuan2, Chao Yu2
1CAS and Shandong Province Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China; Laboratory for Marine Biology and Biotechnology, Qingdao Marine Science and Technology Center, Qingdao, China; College of Marine Sciences, University of Chinese Academy of Sciences, Qingdao, China.
Abstract:
Pyroptosis is a type of programmed cell death mediated by gasdermin (GSDM). GSDM is activated by caspase (CASP), which cleaves GSDM to release the N-terminal (NT) fragment that forms channels in the plasma membrane and leads to cell death. To date, research on pyroptosis in teleost is limited. In this study, we examined the activation and regulation mechanism of pyroptosis in flounder Paralichthys olivaceus. P. olivaceus gasdermin E (PoGSDME) was found to be cleaved by six P. olivaceus caspases (PoCASP1/3a/3b/7/8a/8b). PoCASP1/3a/3b/7 cleaved primarily at 245FEAD248, which generated an NT fragment (NT248) that induced robust pyroptosis. PoCASP8a/8b cleaved both the full length PoGSDME and NT248 at 202IEKD205, thus destroying the biological activity of PoGSDME and NT248. Nine residues crucial for PoGSDME function were identified, of which, F2, L19, and G85 were essential to plasma membrane translocation. During bacterial infection, PoGSDME and PoCASP1 expressions were significantly upregulated in flounder tissues, and PoGSDME, as well as PoCASP1, activation occurred in flounder cells accompanied with the processing cleavage of IL-1β and IL-18. Together these results revealed both the activation and the inhibition mechanisms of GSDME-mediated pyroptosis in flounder, and added new insights into the regulation of pyroptosis in fish.
Insights
Pyroptosis in flounder is regulated by gasdermin E (GSDME) cleavage. Caspases activate GSDME for cell death, while other caspases inhibit it, offering insights into fish pyroptosis mechanisms.
Area of Science:
- Cell Biology
- Immunology
- Molecular Biology
Background:
- Pyroptosis is a programmed cell death pathway crucial for immunity.
- Gasdermin (GSDM) activation by caspases initiates pyroptosis.
- Research on teleost pyroptosis, particularly in fish, remains limited.
Purpose of the Study:
- To investigate the activation and regulation mechanisms of pyroptosis in flounder (Paralichthys olivaceus).
- To identify the specific caspases involved in cleaving flounder gasdermin E (PoGSDME).
- To elucidate the role of PoGSDME in cellular responses during bacterial infection.
Main Methods:
- Analysis of PoGSDME cleavage by six flounder caspases (PoCASP1/3a/3b/7/8a/8b).
- Identification of critical residues for PoGSDME function and plasma membrane translocation.
- Examination of PoGSDME and PoCASP1 expression and activation in flounder tissues during bacterial infection.
Main Results:
- PoCASP1/3a/3b/7 activated PoGSDME at FEAD, inducing pyroptosis.
- PoCASP8a/8b inhibited PoGSDME activity by cleaving at IEKD.
- Bacterial infection upregulated PoGSDME and PoCASP1, leading to IL-1β and IL-18 processing.
Conclusions:
- Flounder GSDME-mediated pyroptosis is regulated by specific caspase cleavage sites, enabling both activation and inhibition.
- Key residues F2, L19, and G85 are essential for PoGSDME translocation.
- This study provides novel insights into pyroptosis regulation in fish, particularly during immune responses.
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