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Updated: Jul 24, 2025
Visualization of G3BP Stress Granules Dynamics in Live Primary Cells
Published on: May 21, 2014
Identification of small molecule inhibitors of G3BP-driven stress granule formation
Brian D Freibaum1, James Messing1, Haruko Nakamura1
1Department of Cell and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, USA.
Abstract:
Stress granule formation is triggered by the release of mRNAs from polysomes and is promoted by the action of the paralogs G3BP1 and G3BP2. G3BP1/2 proteins bind mRNAs and thereby promote the condensation of mRNPs into stress granules. Stress granules have been implicated in several disease states, including cancer and neurodegeneration. Consequently, compounds that limit stress granule formation or promote their dissolution have potential as both experimental tools and novel therapeutics. Herein, we describe two small molecules, referred to as G3BP inhibitor a and b (G3Ia and G3Ib), designed to bind to a specific pocket in G3BP1/2 that is known to be targeted by viral inhibitors of G3BP1/2 function. In addition to disrupting co-condensation of RNA, G3BP1, and caprin 1 in vitro, these compounds inhibit stress granule formation in cells treated prior to or concurrent with stress, and dissolve pre-existing stress granules when added to cells after stress granule formation. These effects are consistent across multiple cell types and a variety of initiating stressors. Thus, these compounds represent ideal tools to probe the biology of stress granules and hold promise for therapeutic interventions designed to modulate stress granule formation.
Insights
New small molecules, G3BP inhibitor a and b, effectively inhibit and dissolve stress granules by targeting G3BP1/2 proteins. These compounds are valuable tools for studying stress granule biology and potential therapeutics.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Stress granules are cellular aggregates implicated in diseases like cancer and neurodegeneration.
- G3BP1 and G3BP2 proteins are key regulators of stress granule formation by binding to mRNAs.
- Modulating stress granule dynamics is a potential therapeutic strategy.
Approach:
- Developed two small molecules, G3BP inhibitor a (G3Ia) and G3BP inhibitor b (G3Ib), targeting a conserved pocket in G3BP1/2.
- Investigated the compounds' ability to disrupt mRNP condensation and stress granule formation *in vitro* and in cellular models.
- Assessed the compounds' efficacy in preventing and dissolving pre-existing stress granules across various cell types and stressors.
Key Points:
- G3Ia and G3Ib disrupt the co-condensation of RNA, G3BP1, and caprin 1 *in vitro*.
- These inhibitors prevent stress granule formation when applied before or during cellular stress.
- The compounds effectively dissolve pre-existing stress granules when administered post-stress.
- Observed consistent effects across multiple cell types and diverse stress-inducing conditions.
Conclusions:
- G3BP inhibitors a and b are potent modulators of stress granule formation and dissolution.
- These small molecules serve as valuable tools for investigating the biological roles of stress granules.
- The compounds show promise as potential therapeutic agents for stress granule-related diseases.
