Rotenone as a Tool for Modeling Mitochondrial Dysfunction Pathways

Introduction

Mitochondrial dysfunction is a central feature of numerous neurodegenerative diseases, metabolic disorders, and cellular stress responses. The search for robust chemical tools to dissect mitochondrial pathways continues to be a priority across molecular biology, neuroscience, and translational research. Rotenone (CAS 83-79-4) stands out as a widely utilized mitochondrial Complex I inhibitor, facilitating investigations into oxidative phosphorylation, reactive oxygen species (ROS) production, apoptosis, and autophagy. Recent advances in mitochondrial proteostasis—particularly the regulation of metabolic enzymes like α-ketoglutarate dehydrogenase (OGDH)—add a new dimension to how rotenone-based models can be interpreted and expanded (Wang et al., Molecular Cell, 2025).

Rotenone: Mechanisms and Applications in Mitochondrial Research

Rotenone is a natural isoflavonoid compound that potently and selectively inhibits mitochondrial Complex I (NADH:ubiquinone oxidoreductase), with an IC₅₀ in the range of 1.7–2.2 μM. By blocking electron transfer within Complex I, rotenone disrupts the mitochondrial proton gradient, leading to impaired ATP synthesis and increased generation of ROS. The resulting oxidative stress is a well-established trigger for mitochondrial dysfunction, apoptosis, and autophagy in multiple cellular contexts.

Rotenone’s characteristics—including its insolubility in ethanol and water but high solubility in DMSO (≥77.6 mg/mL)—make it amenable for in vitro and in vivo studies. Prolonged exposure or high concentrations induce severe mitochondrial injury, making it a reliable mitochondrial dysfunction inducer and apoptosis inducer in SH-SY5Y cells, as well as other neuronal or non-neuronal cell lines. Stock solutions should be stored below -20°C, with attention paid to compound stability, as long-term storage in solution is not recommended.

Rotenone in Neurodegenerative Disease Research and Parkinson’s Disease Models

One of the most significant applications of rotenone is in modeling Parkinson’s disease (PD) and related neurodegenerative disorders. The compound’s ability to induce dopaminergic neuronal loss in the substantia nigra via systemic or intranasal administration has provided a foundation for robust animal models that closely mimic aspects of PD pathology. In differentiated SH-SY5Y neuroblastoma cells, rotenone exposure initiates apoptosis, reduces mitochondrial motility, and elicits biphasic survival responses at nanomolar concentrations over extended periods.

The mechanistic underpinnings involve not only ROS-mediated cell death but also activation of stress-responsive signaling pathways, including p38 MAPK and c-Jun N-terminal kinase (JNK). These cascades mediate downstream events such as caspase activation, mitochondrial outer membrane permeabilization, and the induction of autophagy. Rotenone’s effects on olfactory function and neurite degeneration further extend its utility as a Parkinson’s disease model in rodent systems.

Integrating Rotenone Models with Emerging Mitochondrial Proteostasis Mechanisms

The landscape of mitochondrial research is evolving beyond classical bioenergetics to encompass intricate regulatory networks governing mitochondrial proteostasis. The recent work by Wang et al. (2025) delineates a novel post-translational regulatory mechanism in which the mitochondrial DNAJC-type co-chaperone TCAIM binds specifically to OGDH, the E1 subunit of the α-ketoglutarate dehydrogenase complex. Unlike traditional chaperones, TCAIM reduces OGDH protein levels via HSPA9 (mtHSP70) and the LONP1 protease, directly affecting TCA cycle flux and mitochondrial metabolism.

These findings suggest a previously underappreciated dimension of mitochondrial enzyme regulation—one that may intersect with rotenone-induced metabolic stress. Since both rotenone and TCAIM-mediated OGDH downregulation compromise mitochondrial function, their combined or comparative analysis in cellular models could elucidate compensatory or synergistic proteostatic responses. For example, rotenone’s direct inhibition of Complex I may potentiate the metabolic consequences of OGDH suppression, affecting NAD+/NADH ratios, ROS production, and the stabilization of hypoxia-inducible factor 1-alpha (HIF-1α).

Practical Considerations for Rotenone-Based Signaling and Pathway Research

Rotenone’s versatility as a mitochondrial dysfunction inducer extends into diverse experimental applications. In apoptosis research, it is frequently employed to activate intrinsic cell death machinery, providing a platform for caspase activation assays and the study of mitochondrial outer membrane permeabilization. In autophagy pathway research, rotenone-induced mitochondrial injury triggers mitophagy, allowing for the dissection of upstream and downstream regulators.

In SH-SY5Y cells, rotenone exposure can be titrated to induce graded mitochondrial damage, enabling investigations of biphasic survival curves, threshold effects, and the interplay between apoptosis and autophagic responses. Moreover, the activation of p38 MAPK and JNK signaling pathways by rotenone-generated ROS offers a tractable system for studying stress-responsive kinases in neurodegeneration and cellular adaptation.

Advancing Neurodegenerative Disease Models: Rotenone and Beyond

As research on mitochondrial dysfunction advances, integrating rotenone-based models with emerging insights from mitochondrial proteostasis is crucial. For instance, the combination of rotenone treatment and genetic manipulation of TCAIM or OGDH could reveal new vulnerabilities or adaptive responses in neuronal and non-neuronal cells. High-content phenotyping, metabolomics, and transcriptomic profiling after rotenone exposure—alone or in combination with proteostasis modulators—could shed light on the crosstalk between bioenergetic failure, enzyme degradation, and cell fate decisions.

Furthermore, the specificity of rotenone for Complex I makes it an ideal comparator for dissecting upstream and downstream defects in mitochondrial metabolism. This is especially relevant when investigating the consequences of targeted protein degradation via HSPA9/LONP1 or other post-translational regulatory axes, as described by Wang et al. (2025).

Conclusion

Rotenone remains a cornerstone for mitochondrial dysfunction research, with applications spanning apoptosis, autophagy, ROS-mediated cell death, and neurodegenerative disease modeling. The expanding understanding of mitochondrial proteostasis—particularly the role of DNAJC co-chaperones in regulating metabolic enzyme abundance—offers fertile ground for reinterpreting and extending rotenone-based experimental systems. The convergence of chemical inhibition (Complex I) and targeted protein degradation (OGDH complex) underlines the value of integrated approaches in elucidating mitochondrial pathobiology and in developing next-generation disease models.

This article builds upon, but differs fundamentally from, prior reviews such as Rotenone: A Mitochondrial Complex I Inhibitor for Neurode..., which primarily focus on the pharmacological and in vivo modeling aspects of rotenone. Here, we extend the discourse by explicitly connecting rotenone-induced mitochondrial dysfunction to novel proteostasis mechanisms and post-translational regulation of mitochondrial metabolism, thereby providing a broader framework for future research and experimental design.