Plant Compound Celastrol Clears Senescent Cells and Extends Lifespan in Animal Models
Celastrol outperforms leading senolytics by targeting the Hsc70-Bim protein complex, clearing zombie cells and reducing organ fibrosis in mice and flies.
Summary
Researchers identified celastrol, a compound from traditional medicine plants, as a potent senolytic that selectively destroys senescent 'zombie' cells. It works by disrupting the Hsc70-Bim-CHIP protein complex, stabilizing the pro-apoptotic protein Bim and triggering cell death specifically in aged cells. In animal studies, celastrol extended Drosophila lifespan and reduced lung and liver fibrosis in mice. To address toxicity concerns, scientists engineered a prodrug called CeGal that activates only in senescent cells marked by high β-galactosidase activity, dramatically improving safety. Celastrol outperformed benchmark senolytics ABT-263 and fisetin, suggesting significant translational potential.
Detailed Summary
Cellular senescence — the accumulation of dysfunctional 'zombie' cells that resist normal cell death — is a major driver of aging and age-related diseases including organ fibrosis. Senolytics, drugs that selectively eliminate these cells, represent a promising but still limited therapeutic class. This study investigates celastrol, a pentacyclic triterpenoid derived from traditional medicinal plants, as a novel senolytic agent.
Using both stress-induced and replication-induced senescent cell models, researchers showed that celastrol potently and selectively triggers intrinsic apoptosis in senescent cells, confirmed by caspase-3 cleavage and Annexin V/PI staining, while ferroptosis was ruled out. Mechanistically, proteomic analysis and co-immunoprecipitation identified Hsc70 as a direct binding target of celastrol. The compound disrupts an Hsc70-Bim-CHIP complex, reducing ubiquitin-mediated degradation of Bim and allowing this pro-death protein to accumulate and activate caspases. Knockdown of Bim significantly blunted celastrol's senolytic effect, confirming pathway specificity.
In vivo, celastrol reduced intestinal senescence and extended both median and maximum lifespan in Drosophila. In mouse models, it mitigated bleomycin-induced pulmonary fibrosis and CCl₄-induced hepatic fibrosis, with elevated cleaved caspase-3 specifically observed in p16-positive senescent cells — a strong marker of on-target activity.
To address systemic toxicity, the team developed CeGal, a β-galactosidase-activated prodrug that releases celastrol preferentially in senescent cells. CeGal maintained senolytic efficacy while markedly reducing off-target toxicity, substantially improving the therapeutic window.
Caveats include reliance on animal models and in vitro systems; human clinical data are absent. The prodrug strategy is promising but requires further pharmacokinetic and safety validation before human trials.
Key Findings
- Celastrol outperformed benchmark senolytics ABT-263 and fisetin in selective elimination of senescent cells.
- Celastrol disrupts Hsc70-Bim-CHIP complex, stabilizing pro-apoptotic Bim and triggering caspase-mediated cell death.
- Celastrol extended median and maximum lifespan in Drosophila and reduced lung and liver fibrosis in mice.
- Prodrug CeGal activates selectively in β-galactosidase-high senescent cells, dramatically reducing systemic toxicity.
- Bim knockdown attenuated senolysis, confirming Hsc70-Bim axis as the primary mechanism of action.
Methodology
Study used stress- and replication-induced senescent cell models alongside proteomics, co-immunoprecipitation, mass spectrometry, biolayer interferometry, ubiquitination assays, and RNAi for mechanistic work. In vivo studies included Drosophila lifespan assays and bleomycin/CCl₄ murine fibrosis models. A β-galactosidase-activated prodrug (CeGal) was engineered and tested for improved safety.
Study Limitations
All efficacy data come from animal models (mice and Drosophila) and cell culture; no human clinical data are yet available. Systemic toxicity of native celastrol remains a concern, and CeGal's pharmacokinetics require further validation in higher-order organisms before clinical trials can be considered.
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