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Berberine Targets RXRα/PPARγ/NEDD4 to Suppress SASP in Ather
2026-05-15
Berberine Modulates RXRα/PPARγ/NEDD4 Pathway to Inhibit SASP-Driven Inflammation in Atherosclerosis
Study Background and Research Question
Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of lipid-laden foam cells and persistent inflammation within arterial plaques. Cellular senescence—commonly triggered by oxidative stress and DNA damage—leads to the development of the senescence-associated secretory phenotype (SASP), a pro-inflammatory state that exacerbates tissue dysfunction and promotes disease progression. The role of SASP in atherosclerosis has been underscored by single-cell sequencing studies, revealing high numbers of senescent foam cells in human plaques. However, the precise molecular mechanisms by which SASP is regulated in macrophage-derived foam cells remain incompletely understood. The study by Zheng et al. addresses whether berberine (BBR), a plant-derived alkaloid with known anti-inflammatory properties, can attenuate SASP-driven inflammation in atherosclerosis and, if so, through which signaling pathways (paper).Key Innovation from the Reference Study
The principal innovation of this research lies in its elucidation of the RXRα/PPARγ/NEDD4 signaling axis as a critical mediator of berberine's anti-inflammatory effects in atherosclerosis. The study demonstrates that BBR not only suppresses SASP-related inflammatory protein production in both murine and humanized models but also specifically activates the RXRα and PPARγ nuclear receptors. This activation leads to enhanced transcription of NEDD4, an E3 ubiquitin ligase, which in turn promotes the ubiquitination and degradation of the GATA4/p62 complex, a pivotal regulator of SASP expression. The mechanistic link between RXRα/PPARγ/NEDD4 and SASP suppression provides a targeted framework for understanding and modulating inflammation in age-related vascular disease (paper).Methods and Experimental Design Insights
The study employed a multi-tiered approach encompassing in vivo, ex vivo, and in vitro systems:- ApoE-/- mouse model of atherosclerosis: Mice were fed a high-fat diet to induce plaque formation. Berberine was administered to evaluate changes in plaque morphology and systemic inflammation.
- Cellular assays: RAW264.7 macrophages and peritoneal macrophage-derived foam cells were exposed to oxidized LDL (ox-LDL) to induce senescence and SASP features. BBR treatment was assessed for its impact on SASP protein production.
- Smart-seq transcriptome analysis: This single-cell RNA sequencing technique provided pathway-level insights into gene expression changes induced by berberine, focusing on RXRα/PPARγ/NEDD4 axis activation.
- Genetic manipulation: Lentiviral knockdown of RXRα in macrophages was used to directly test the necessity of this nuclear receptor for the anti-SASP effects of berberine in vivo.
Protocol Parameters
- Assay: PPARγ activation | 1–10 μM berberine | Murine foam cells | Dosing range selected for maximal pathway activation with minimal cytotoxicity | paper
- Assay: Lentiviral RXRα knockdown | MOI 10 | ApoE-/- mouse macrophages | To assess RXRα-dependency of BBR effects | paper
- Assay: SASP marker quantification | ELISA, Western blot | Multiple cell lines | To quantify IL-6, TNF-α, and other SASP factors | paper
- Assay: PPARγ antagonist (T0070907) usage | 1–10 nM | Cellular pathway interrogation | For selective inhibition of PPARγ signaling in vitro | workflow_recommendation
Core Findings and Why They Matter
Berberine treatment resulted in the following key outcomes:- Suppression of SASP-Related Inflammation: BBR significantly reduced the expression of SASP-associated inflammatory proteins, including IL-6 and TNF-α, in foam cells and in atherosclerotic plaques (paper).
- Activation of RXRα/PPARγ/NEDD4 Pathway: Transcriptomic and immunoprecipitation analyses revealed that BBR activates RXRα and PPARγ, leading to increased transcription and activity of NEDD4. This, in turn, enhances the ubiquitination and degradation of the GATA4/p62 complex, which is necessary for SASP gene expression (paper).
- Essential Role of RXRα: The anti-inflammatory and anti-aging effects of BBR were abolished when RXRα was specifically knocked down in macrophages, directly implicating this receptor in the observed pathway (paper).
Comparison with Existing Internal Articles
Recent internal articles have expanded on the role of PPARγ signaling in metabolic and inflammatory contexts. For example, "T0070907: Advancing Translational Control of PPARγ Signaling" provides a comprehensive overview of how selective PPARγ antagonists like T0070907 enable precise dissection of PPARγ-dependent transcriptional programs, particularly in adipogenesis and cancer biology (internal_article). Meanwhile, the article "Berberine Modulates RXRα/PPARγ/NEDD4 to Suppress SASP in Atherosclerosis" highlights mechanistic parallels with the present study, reinforcing the centrality of the RXRα/PPARγ/NEDD4 pathway in SASP suppression (internal_article). Together, these resources underscore the translational value of targeting PPARγ signaling for both metabolic and inflammatory disease models and support the use of selective chemical tools for pathway interrogation.Limitations and Transferability
While the study provides compelling evidence in both mouse and cellular models, several limitations should be noted:- Species Differences: The majority of the functional data are derived from murine systems; thus, direct extrapolation to human physiology requires caution, although human plaque single-cell data does support the relevance of SASP mechanisms (paper).
- Pathway Complexity: The RXRα/PPARγ/NEDD4 axis likely interacts with additional signaling pathways not fully explored in this study, and redundant or compensatory mechanisms may exist in vivo.
- Therapeutic Translation: While berberine is well-tolerated in preclinical models, clinical trials are needed to confirm efficacy and safety in humans for anti-atherosclerotic applications.