Negative regulation of the NLRP1 inflammasome by B-cell lymphoma-2-like molecule in Cyprinus carpio L.

Upon stimulation, NLRP1 assembles into an inflammasome complex to defend against pathogen invasion and protect the host. However, excessive activation of NLRP1 can disrupt immune homeostasis and contribute to various inflammatory diseases. Therefore, understanding the regulatory mechanisms of the NLRP1 inflammasome is of significant importance. The B-cell lymphoma-2 (BCL-2) protein family, known as key regulators of mitochondrial outer membrane permeability, plays a central role in the mitochondrial-mediated apoptosis pathway. In the present study, we cloned the anti-apoptotic protein CcBCL-2-like sequence from the genome of common carp and discovered that it could interact with NLRP1 and participate in the regulation of pyroptosis. The qPCR analysis showed that CcBCL-2-like was highly expressed in the brain and intestinal tissues of healthy common carp (n = 3), and the expression of CcBCL-2-like in intestinal tissue was significantly upregulated following stimulation with A. hydrophila and E. tarda. Immunofluorescence assays indicated that CcBCL-2-like localized both in the nucleus and cytoplasm. Furthermore, co-immunoprecipitation and co-localization experiments demonstrated a direct interaction between CcBCL-2-like and CcNLRP1 in 293T and EPC cells. Functional analysis of inflammasome downstream pathways revealed that CcBCL-2-like significantly inhibited ASC oligomerization, caspase-1 enzymatic activity, LDH release, and pyroptosis triggered by the CcNLRP1 inflammasome. These findings provide a theoretical foundation for further elucidating the activation mechanism of CcNLRP1 and for developing strategies to prevent and treat infectious diseases in fish.