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Updated: Jun 4, 2025
Measurement of Fatty Acid β-Oxidation in a Suspension of Freshly Isolated Mouse Hepatocytes
Published on: September 9, 2021
Downregulation of the MARC1 p.A165 risk allele reduces hepatocyte lipid content by increasing beta-oxidation
Ester Ciociola1, Tanmoy Dutta1, Kavitha Sasidharan1
1Department of Molecular and Clinical Medicine, Institute of Medicine, The Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden.
Background/Aims:
Metabolic dysfunction-associated steatotic liver disease (MASLD) is a global epidemic. The disease has a strong genetic component, and a common missense variant (rs2642438) in the mitochondrial amidoxime-reducing component 1 (MARC1) gene confers protection against its onset and severity. However, there are contrasting results regarding the mechanisms that promote this protection.
Methods:
We downregulated MARC1 in primary human hepatocytes (PHHs) using short interfering RNA (siRNA). We measured neutral lipid content by Oil-Red O staining and fatty acid oxidation by radiolabeled tracers. We also performed RNA-sequencing and proteomic analysis using LC-MS. Additionally, we analyzed data from 239,075 participants from the UK Biobank.
Results:
Downregulation of MARC1 reduced neutral lipid content in PHHs homozygous for the wild type (p.A165, risk), but not for the mutant (p.T165, protective), allele. We found that this reduction was mediated by increased fatty acid utilization via β-oxidation. Consistent with these results, we found that the levels of 3-hydroxybutyrate, a by-product of β-oxidation, were higher in carriers of the rs2642438 minor allele among samples from the UK biobank, indicating higher β-oxidation in these individuals. Moreover, downregulation of the MARC1 p.A165 variant resulted in a more favorable phenotype by reducing ferroptosis and reactive oxygen species levels.
Conclusion:
MARC1 downregulation in carriers of the risk allele results in lower hepatocyte neutral lipids content due to higher β-oxidation, while upregulating beneficial pathways involved in cell survival.
Insights
Downregulating the MARC1 gene lowers liver fat in individuals with metabolic dysfunction-associated steatotic liver disease (MASLD) by increasing fatty acid burning. This protective effect is linked to the rs2642438 variant and enhances cell survival pathways.
Area of Science:
- Hepatology
- Genetics
- Metabolic Disorders
Background:
- Metabolic dysfunction-associated steatotic liver disease (MASLD) is a widespread condition with a significant genetic influence.
- A common variant in the MARC1 gene (rs2642438) is associated with protection against MASLD, but the underlying mechanisms are debated.
Purpose of the Study:
- To investigate the protective mechanisms of the rs2642438 variant in the MARC1 gene against MASLD.
- To determine how MARC1 influences lipid metabolism and cellular pathways in hepatocytes.
Main Methods:
- Short interfering RNA (siRNA) was used to reduce MARC1 expression in primary human hepatocytes (PHHs).
- Neutral lipid content was assessed using Oil-Red O staining, and fatty acid oxidation was measured with radiolabeled tracers.
- RNA-sequencing, LC-MS proteomic analysis, and UK Biobank data from 239,075 participants were utilized.
Main Results:
- MARC1 downregulation decreased neutral lipid content in wild-type PHHs (p.A165, risk allele) but not in mutant PHHs (p.T165, protective allele).
- This reduction was attributed to enhanced fatty acid utilization via β-oxidation, supported by higher 3-hydroxybutyrate levels in UK Biobank participants carrying the protective rs2642438 minor allele.
- Downregulating the MARC1 p.A165 variant reduced ferroptosis and reactive oxygen species, indicating a more favorable cellular phenotype.
Conclusions:
- MARC1 downregulation in individuals with the MASLD risk allele lowers hepatocyte neutral lipid content by boosting β-oxidation.
- This process also activates beneficial cell survival pathways, offering a potential therapeutic strategy for MASLD.
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