Ciociola Ester, Dutta Tanmoy, Sasidharan Kavitha, Kovooru Lohitesh, Noto Francesca R, Pennisi Grazia, Petta Salvatore, Mirarchi Angela, Maurotti Samantha, Scopacasa Bernardette, Tirinato Luca, Candeloro Patrizio, Henricsson Marcus, Lindén Daniel, Jamialahmadi Oveis, Pujia Arturo, Mancina Rosellina M, Romeo Stefano
Department of Molecular and Clinical Medicine, Institute of Medicine, The Sahlgrenska Academy, Wallenberg Laboratory, University of Gothenburg, Gothenburg, Sweden.
Department of Experimental and Clinical Medicine, University of Magna Graecia, Catanzaro, Italy.
Clin Mol Hepatol. 2025 Apr;31(2):445-459. doi: 10.3350/cmh.2024.0642. Epub 2024 Dec 23.
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.
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.
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.
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.
背景/目的：代谢功能障碍相关脂肪性肝病（MASLD）是一种全球性流行病。该疾病具有很强的遗传成分，线粒体偕胺肟还原成分1（MARC1）基因中的一个常见错义变体（rs2642438）可预防其发病和减轻其严重程度。然而，关于促进这种保护作用的机制存在相互矛盾的结果。
我们使用小干扰RNA（siRNA）在原代人肝细胞（PHH）中下调MARC1。我们通过油红O染色测量中性脂质含量，并通过放射性标记示踪剂测量脂肪酸氧化。我们还使用液相色谱-质谱联用（LC-MS）进行RNA测序和蛋白质组分析。此外，我们分析了来自英国生物银行的239,075名参与者的数据。
MARC1的下调降低了野生型（p.A165，风险）纯合子PHH中的中性脂质含量，但对突变型（p.T165，保护性）等位基因的PHH没有影响。我们发现这种降低是通过β氧化增加脂肪酸利用来介导的。与这些结果一致，我们发现来自英国生物银行样本中rs2642438次要等位基因携带者中β氧化的副产物3-羟基丁酸水平较高，表明这些个体中β氧化较高。此外，MARC1 p.A165变体的下调通过降低铁死亡和活性氧水平产生了更有利的表型。
风险等位基因携带者中MARC1的下调由于更高的β氧化导致肝细胞中性脂质含量降低，同时上调了参与细胞存活的有益途径。
