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Cited by 161Mitochondrial Function and PathologyDrug-Induced Hepatotoxicity and ProtectionAutophagy in Disease and Therapy

Palmitate-induced Activation of Mitochondrial Metabolism Promotes Oxidative Stress and Apoptosis in H4IIEC3 Rat Hepatocytes

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Egnatchik, Robert A., Leamy, Alexandra K., Noguchi, Yasushi, Shiota, Masakazu, Young, Jamey D.·2014·Metabolism
DOI 10.1016/j.metabol.2013.10.009PMC PMC3946971
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Abstract

Objective Hepatic lipotoxicity is characterized by reactive oxygen species (ROS) accumulation, mitochondrial dysfunction, and excessive apoptosis, but the precise sequence of biochemical events leading to oxidative damage and cell death remains unclear. The goal of this study was to delineate the role of mitochondrial metabolism in mediating hepatocyte lipotoxicity. Materials/methods We treated H4IIEC3 rat hepatoma cells with free fatty acids in combination with antioxidants and mitochondrial inhibitors designed to block key events in the progression toward apoptosis. We then applied (13)C metabolic flux analysis (MFA) to quantify mitochondrial pathway alterations associated with these treatments. Results Treatment with palmitate alone led to a doubling in oxygen uptake rate and in most mitochondrial fluxes. Supplementing culture media with the antioxidant N-acetyl-cysteine (NAC) reduced ROS accumulation and caspase activation and partially restored cell viability. However, (13)C MFA revealed that treatment with NAC did not normalize palmitate-induced metabolic alterations, indicating that neither elevated ROS nor downstream apoptotic events contributed to mitochondrial activation. To directly limit mitochondrial metabolism, the complex I inhibitor phenformin was added to cells treated with palmitate. Phenformin addition eliminated abnormal ROS accumulation, prevented the appearance of apoptotic markers, and normalized mitochondrial carbon flow. Further studies revealed that glutamine provided the primary fuel for elevated mitochondrial metabolism in the presence of palmitate, rather than fatty acid beta-oxidation, and that glutamine consumption could be reduced through co-treatment with phenformin but not NAC. Conclusion Our results indicate that ROS accumulation in palmitate-treated H4IIEC3 cells occurs downstream of altered mitochondrial oxidative metabolism, which is independent of beta-oxidation and precedes apoptosis initiation.

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  • ROS accumulation triggers damaging cascades: a decrease in mitochondrial membrane potential, activation of caspases 3/7, apoptosis, and ER stress and inflammation via NF-κB.

    “ROS accumulation triggers damaging cascades: a decrease in mitochondrial membrane potential, activation of caspases 3/7, apoptosis, and ER stress and inflammation via NF-κB [90,152,153,154,155].”

    From The HepG2 Cell Line as a Model for Studying Metabolic Dysfunction-Associated Steatotic Liver Disease (2026) · cites this paper as [154]

    The Discussion (page not specified in our copy) reports that ROS accumulation preceded apoptosis in palmitate-treated H4IIEC3 cells and that reducing ROS also reduced caspase activation. It does not establish that ROS decreases mitochondrial membrane potential or causes ER stress and inflammation via NF-κB. (LLM, conf=0.88)

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References 37 · Cited by 161

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Authors
Egnatchik, R. A., Leamy, A. K., Noguchi, Y., Shiota, M., & Young, J. D.
Affiliations
  • Vanderbilt University (US)
  • Ajinomoto (Japan) (JP)
ORCID
Venue
Metabolism
Publisher
Elsevier BV
Published
2014-02
Volume
63
Issue
2
Pages
283-295
ISSN
0026-0495 (ISSN-L)
DOI
10.1016/j.metabol.2013.10.009
PMC
PMC3946971
OpenAlex
W2006241936
Cited by
161
References
37
Citations by year
2026: 6 · 2025: 10 · 2024: 12 · 2023: 12 · 2022: 12 · 2021: 22 · 2020: 16 · 2019: 12 · 2018: 19 · 2017: 10 · 2016: 11 · 2015: 8 · 2014: 11
FWCI
4.48
Type
journal article
Language
en
Open access
Licence
Locations
  • Metabolism (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
Funders
  • National Institutes of Health (5p60dk020593-31)
  • National Institute of Diabetes and Digestive and Kidney Diseases (DK 020593, P60-DK020593, P30DK020593)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Mitochondrial Function and Pathology
  • Life Sciences › Pharmacology, Toxicology and Pharmaceutics › Pharmacology › Drug-Induced Hepatotoxicity and Protection
  • Health Sciences › Medicine › Epidemiology › Autophagy in Disease and Therapy
Keywords
palmitate, hepatic lipotoxicity, mitochondrial metabolism, oxidative stress, apoptosis, reactive oxygen species, N-acetylcysteine, phenformin, glutamine, mitochondrial complex I, fatty acid beta-oxidation, 13C metabolic flux analysis, caspase activation
MeSH terms
Acetylcysteine, Animals, Antioxidants, Carbon Isotopes, Enzyme Activation, Carcinoma, Hepatocellular, Liver Neoplasms, Mitochondria, Liver, Palmitates, Apoptosis, Reactive Oxygen Species, Oxidative Stress, Hepatocytes, Cell Line, Tumor, Rats, Caspases, Effector, Metabolic Flux Analysis

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