Decoding the NF-κB–YAP–NLRP3 Axis in Ulcerative Colitis Pyroptosis

Study Background and Research Question

Ulcerative colitis (UC) is a chronic inflammatory bowel disease characterized by recurrent mucosal inflammation and epithelial injury in the colon. Disease onset and progression are tightly linked to dysregulated immune responses, with aberrant activation of the intestinal mucosal immune system acting as a central driver. Pyroptosis—a form of pro-inflammatory programmed cell death mediated by inflammasomes—has recently garnered attention as an important contributor to UC pathogenesis. However, the upstream regulatory networks controlling pyroptosis in colonic epithelial cells remain only partly understood. The present study interrogates the functional relationship between Yes-associated protein (YAP), a pivotal Hippo pathway effector, and the nuclear factor kappa B (NF-κB) p65 subunit in orchestrating NLRP3 inflammasome activation and pyroptotic cell death during UC (paper).

Key Innovation from the Reference Study

This research delineates a novel mechanistic axis in which NF-κB p65, upon activation in colonic epithelial inflammation, phosphorylates and inactivates YAP via LATS1 kinase upregulation. Inactive YAP loses its ability to repress NLRP3 transcription, resulting in heightened NLRP3 inflammasome activation and subsequent pyroptosis. The study provides direct evidence that the NF-κB–YAP–NLRP3 pathway is a critical regulatory node in UC, connecting immune signaling with cell death regulation at the transcriptional level (paper).

Methods and Experimental Design Insights

The investigation employed both in vitro and in vivo models:

• In vitro: Pyroptosis was induced in human FHC colonic epithelial cells using LPS and ATP. YAP function was modulated via lentiviral overexpression, and downstream effects on pyroptosis and NLRP3 transcription were monitored.
• In vivo: Colitis was modeled in mice using dextran sodium sulfate (DSS), both in wild-type and GSDMD (gasdermin D) knockout backgrounds. YAP was overexpressed in mice using lentiviral vectors.
• Molecular Mechanisms: Nucleoplasmic separation and chromatin immunoprecipitation (ChIP) were used to map YAP binding to the NLRP3 promoter and assess changes in transcriptional repression. Phosphorylation status of YAP and its nuclear localization were evaluated under conditions of NF-κB p65 activation.

The breadth of models and mechanistic assays ensured robust attribution of observed phenomena to the NF-κB–YAP–NLRP3 axis, mapping both upstream (NF-κB p65/LATS1) and downstream (NLRP3, GSDMD-mediated pyroptosis) events (paper).

Core Findings and Why They Matter

• Elevated Pyroptosis in UC: Both UC patient samples and DSS-induced colitic mice exhibited increased GSDMD-driven pyroptosis, correlating with disease severity.
• YAP Suppresses Pyroptosis: Overexpression of YAP in FHC cells reduced pyroptosis and downregulated NLRP3 expression, supporting its role as a transcriptional repressor of NLRP3.
• NF-κB p65 Inactivates YAP via LATS1: NF-κB p65, highly activated during colonic inflammation and pyroptosis, induces LATS1-mediated phosphorylation of YAP. Phosphorylated YAP is sequestered in the cytoplasm, reducing nuclear YAP and thus NLRP3 repression.
• Functional Epistasis in Mice: Genetic ablation of GSDMD substantially attenuated DSS-induced colitis, highlighting the pathogenic importance of pyroptosis. Notably, YAP overexpression in GSDMD knockout mice did not further reduce inflammation, confirming that YAP’s protective effects are pyroptosis-dependent.

This integrated model demonstrates how inflammatory signaling (NF-κB p65) can dynamically inactivate a tissue-protective pathway (YAP), thereby unleashing NLRP3-driven pyroptosis and amplifying mucosal injury in UC (paper).

Comparison with Existing Internal Articles

The mechanistic insights from this study align with and expand upon prior thematic reviews of NF-κB inhibitors in inflammation research. For example, the article "JSH-23 and the Future of Precision NF-κB Inhibition" (internal article) highlights how selective NF-κB p65 inhibitors, such as JSH-23, can be leveraged to dissect inflammatory signaling events and modulate inflammasome activity. Similarly, "JSH-23: Advanced Strategies in NF-κB Inhibition for Inflammation Research" (internal article) discusses the unique value of small-molecule NF-κB inhibitors for modeling cellular responses to pro-inflammatory cues, including those that govern pyroptosis. However, the present reference study provides direct experimental evidence that NF-κB p65 not only drives inflammatory gene expression, but also suppresses anti-pyroptotic mechanisms via YAP inactivation—a layer of regulation not previously addressed in those reviews.

Limitations and Transferability

While the study convincingly maps the NF-κB–YAP–NLRP3 axis in both cell and mouse models, several caveats remain:

• The role of other Hippo pathway components in colonic inflammation is not fully explored.
• Human tissue validation is correlative; definitive mechanistic studies in primary human epithelium are still required.
• Therapeutic implications are inferred from genetic and molecular manipulation, not from pharmacological intervention.

Therefore, while the findings are robust within the context of UC and pyroptosis, extrapolation to other inflammatory contexts or tissue types should be approached with caution (workflow_recommendation).

Protocol Parameters

• assay: Induction of epithelial pyroptosis | value: LPS (1 μg/mL) + ATP (5 mM), 4 h | applicability: FHC cell model for pyroptosis | rationale: Mimics DAMP/PAMP-driven inflammasome activation in colonic epithelium | source_type: paper
• assay: DSS-induced colitis | value: DSS 2.5-3.5% in drinking water, 5-7 days | applicability: Mouse model of UC | rationale: Standard chemical induction of mucosal inflammation and cell death | source_type: paper
• assay: YAP overexpression | value: Lentiviral vector, MOI 10-20 | applicability: Gain-of-function studies in vitro/in vivo | rationale: Dissects YAP’s effect on NLRP3 transcription and pyroptosis | source_type: paper
• assay: NF-κB inhibition (pharmacological) | value: JSH-23 at 10-40 μM in vitro, 20-40 mg/kg i.p. in mice | applicability: Inhibition of NF-κB p65 nuclear translocation and gene transcription | rationale: Selective blockade of NF-κB-driven signaling for mechanistic and therapeutic studies | source_type: product_spec
• assay: Nucleoplasmic separation/ChIP | value: standard protocols | applicability: Assessing YAP subcellular localization and promoter binding | rationale: Mechanistic mapping of transcriptional regulation | source_type: paper

Research Support Resources

For researchers aiming to interrogate NF-κB–dependent inflammation or dissect the crosstalk between NF-κB and Hippo pathway effectors, selective inhibitors of NF-κB nuclear translocation are essential. JSH-23 (SKU B1645, APExBIO), a well-characterized small-molecule NF-κB inhibitor, is available to support mechanistic studies of NF-κB signaling, pro-inflammatory cytokine inhibition, and inflammasome regulation in both cellular and animal models (source: product_spec). For comparative guidance and troubleshooting, internal articles on advanced NF-κB inhibition strategies can provide additional perspectives on experimental design and translational considerations (internal article).