# Mechanism of Muscimol as a Novel Pyroptosis Inhibitor

> **NIH NIH R21** · UNIVERSITY OF WASHINGTON · 2024 · $233,250

## Abstract

Project Summary
Pyroptosis is a programmed process of lytic, pro-inflammatory cell death that is involved in the pathogenesis of
leading global causes of mortality. Inflammasome-mediated innate immune signaling activates caspase-1
family proteases to initiate pyroptosis by cleaving the pore-forming protein, gasdermin D. Recent data
demonstrate that the protein ninjurin-1 oligomerizes during pyroptosis and is required for plasma membrane
rupture, or cell lysis, downstream of gasdermin D pore formation. Cellular factors released during pyroptotic
lysis cause local and systemic inflammation and pathology, but processes that regulate plasma membrane
rupture and whether these can be therapeutically targeted, are not well-understood. We recently identified
muscimol as a novel inhibitor of pyroptotic lysis, but its mechanism of action is not yet known. Muscimol is
well-studied as an agonist of neuronal GABA receptors, but our preliminary data suggest that inhibition of
pyroptotic lysis is not mediated by these receptors. This proposal aims to understand how muscimol prevents
pyroptotic lysis and identify muscimol analogs with potent and specific activity.
The experiments outlined in this proposal will systematically examine steps in the process of pyroptosis for
inhibition by muscimol. Based on preliminary data, we will focus experiments on the hypothesis that muscimol
interferes with ninjurin-1 oligomerization, while also testing other possibilities. We will use complementary
models of pyroptosis induced by inflammasome-dependent and -independent stimuli, and further employ
reductionist systems based on our findings. Our preliminary data suggest that there are specific molecular
determinants for muscimol inhibition of pyroptotic lysis, as analogs demonstrate varied potency from the parent
molecule, not correlating with GABA receptor activity. We will systematically test a panel of rationally-selected,
already synthesized, muscimol analogs for inhibition of pyroptotic lysis. We hypothesize that our results will
reveal a novel structure-activity relationship for muscimol inhibition of plasma membrane rupture compared to
its canonical activity at neuronal receptors. In addition, these experiments may yield analogs with increased
potency and / or specific activity to prevent pyroptotic lysis, without activity at GABA receptors. Finally, we will
utilize the unique chemical properties of muscimol, coupled with advances in proteomics and the expertise of
our collaborators, to identify novel muscimol-binding proteins. Together, the results of these experiments will
inform a precise molecular understanding of the mechanism of action to disrupt pyroptotic lysis and provide the
foundation for a novel therapeutic strategy for the many diseases in which pyroptosis has been implicated.

## Key facts

- **NIH application ID:** 10877184
- **Project number:** 5R21AI178367-02
- **Recipient organization:** UNIVERSITY OF WASHINGTON
- **Principal Investigator:** Susan Leilani Fink
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $233,250
- **Award type:** 5
- **Project period:** 2023-07-01 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10877184

## Citation

> US National Institutes of Health, RePORTER application 10877184, Mechanism of Muscimol as a Novel Pyroptosis Inhibitor (5R21AI178367-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10877184. Licensed CC0.

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