NF-κB p65–Mediated YAP Inactivation Drives Pyroptosis in Ulcerative Colitis

Study Background and Research Question

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by relapsing mucosal inflammation and epithelial cell injury. Despite advances in biologic therapies, current treatments are limited by incomplete efficacy and potential adverse effects, making it crucial to decipher the molecular networks driving mucosal immune activation. Recent research has underscored the role of pyroptosis—a pro-inflammatory, inflammasome-dependent form of cell death mediated by gasdermin D (GSDMD)—in the progression of UC. However, the upstream regulatory mechanisms controlling pyroptosis in colonic epithelial cells remain incompletely defined. The recent study by Mengmeng Xu et al. (view reference) addresses a central question: How does the interplay between the Hippo pathway effector YAP and the NF-κB signaling axis influence pyroptosis and epithelial injury in UC?

Key Innovation from the Reference Study

The study introduces a previously unrecognized regulatory circuit in which NF-κB p65 activation leads to YAP inactivation, thereby releasing NLRP3 inflammasome expression and promoting epithelial pyroptosis. This mechanism provides direct evidence that YAP functions as a transcriptional repressor of NLRP3, and that its activity is negatively regulated by NF-κB p65-mediated phosphorylation and cytoplasmic sequestration. The identification of this signaling axis fills a critical gap in our understanding of how inflammatory transcription factors modulate programmed cell death during mucosal inflammation. By linking NF-κB–driven YAP inactivation to exacerbated pyroptosis, the study highlights potential molecular targets for selective intervention in inflammation research and NF-κB signaling pathway study.

Methods and Experimental Design Insights

The research team employed a multifaceted approach that integrated cellular, molecular, and in vivo methodologies:

• In vitro models: Human colonic FHC cells were exposed to lipopolysaccharide (LPS) and ATP to induce pyroptosis. Lentiviral YAP overexpression was used to dissect functional roles in epithelial cell death.
• In vivo mouse models: Dextran sulfate sodium (DSS) was used to induce colitis in wild-type and GSDMD-knockout mice. Intraperitoneal injection of YAP-overexpressing lentivirus allowed investigation of YAP's protective effects in colitis.
• Mechanistic interrogations: Nucleoplasmic fractionation and chromatin immunoprecipitation (ChIP) assays demonstrated YAP binding to the NLRP3 promoter. Phosphorylation status and subcellular localization of YAP were probed following NF-κB p65 activation.
• Pyroptosis and inflammation assessment: Levels of cleaved GSDMD, NLRP3, IL-1β, and IL-18 were measured by Western blot, qPCR, and immunohistochemistry in both cell and tissue samples.

Core Findings and Why They Matter

Key discoveries from the reference study include:

• Elevated pyroptosis in UC: Both clinical samples from UC patients and DSS-induced mouse colitis models showed increased expression of pyroptosis markers (cleaved GSDMD, NLRP3, IL-1β).
• YAP represses NLRP3-driven pyroptosis: Forced YAP overexpression in FHC cells and in vivo reduced pyroptosis and inflammatory cytokine release, as evidenced by suppressed GSDMD cleavage and pro-inflammatory cytokine inhibition.
• NF-κB p65 as a negative regulator of YAP: NF-κB p65 activation in inflamed epithelial cells upregulated LATS1-mediated YAP phosphorylation. This modification blocked YAP nuclear translocation and reduced its abundance, thereby decreasing its repressive effect on the NLRP3 promoter.
• Genetic loss of GSDMD mitigates colitis: GSDMD-knockout mice exhibited dramatically attenuated colitis severity, confirming pyroptosis as a driver of epithelial injury. Overexpressing YAP in this context did not further improve outcomes, indicating YAP's protective effects are dependent on the pyroptosis pathway.

These findings provide robust mechanistic evidence that the NF-κB–YAP–NLRP3 axis is central to the regulation of epithelial pyroptosis in UC, offering new perspectives on the pathogenesis and potential molecular targeting of chronic colonic inflammation.

Comparison with Existing Internal Articles

The mechanistic insights from this reference study complement and extend the foundation laid by recent thought-leadership articles on NF-κB inhibition and inflammation research. For example, the internal article "JSH-23: Precision NF-κB Inhibitor for Advanced Inflammation Research" discusses the use of JSH-23, a selective NF-κB p65 inhibitor, in dissecting the transcriptional control of inflammatory cytokines and pyroptosis-related genes. The present study's demonstration that NF-κB p65 directly governs YAP-mediated repression of NLRP3 provides a molecular rationale for using NF-κB inhibitors to modulate inflammasome activity in disease models.

Further, the article "JSH-23 and the Future of Precision NF-κB Inhibition: Mechanistic Insights and Experimental Validation" highlights how small molecule NF-κB inhibitors are deployed to refine preclinical models of inflammation, which aligns with the reference study’s use of genetic and pharmacological modulation of NF-κB signaling to dissect colitis pathogenesis.

Limitations and Transferability

While the study provides compelling evidence for the NF-κB–YAP–NLRP3 axis in colonic epithelial pyroptosis, several limitations must be considered:

• Species and model specificity: The principal findings rely on DSS-induced murine colitis and immortalized human colonic epithelial cells. Transferability to human UC pathogenesis requires further validation in primary human tissues and diverse in vivo models.
• Temporal and spatial regulation: The dynamic interplay between NF-κB activation, YAP phosphorylation, and NLRP3 expression may differ between acute and chronic inflammation stages, and among different cell types within the colonic mucosa.
• Pathway crosstalk: While this study focuses on YAP and NLRP3, NF-κB regulates a broader transcriptional network, and interfering with its activity may have pleiotropic effects, including on wound healing and immune defense.

Despite these limitations, the mechanistic clarity and experimental rigor support the relevance of the NF-κB–YAP–NLRP3 axis as a platform for future inflammation research and translational applications.

Protocol Parameters

• DSS-induced colitis: 2–3% DSS in drinking water for 5–7 days to induce acute colonic inflammation in mice (refer to reference study).
• YAP overexpression: Lentiviral vector delivery via intraperitoneal injection; titration and timing based on disease induction protocol.
• NF-κB modulation: Pharmacological inhibition or genetic knockdown can be used to dissect pathway roles. For selective inhibition of NF-κB transcriptional activity, small molecule inhibitors such as JSH-23 have been widely adopted (see internal article).
• Pyroptosis assessment: Immunoblotting for cleaved GSDMD and NLRP3, qPCR for pro-inflammatory cytokines (IL-1β, IL-18), and histological analysis of tissue injury.

Research Support Resources

Researchers seeking to model NF-κB–dependent inflammatory signaling and its impact on epithelial cell fate can leverage validated chemical tools to complement genetic models. JSH-23 (SKU B1645) from APExBIO is a well-characterized small molecule NF-κB inhibitor that selectively blocks p65 nuclear translocation and transcriptional activity, supporting reproducible pro-inflammatory cytokine inhibition in both in vitro and in vivo systems. Its utility in disease models such as cisplatin-induced acute kidney injury has been documented, and similar workflows can be adapted for colitis and inflammasome research. For optimal experimental results, researchers should review product solubility and handling protocols as recommended in the product information.