Department of Medicine, Karsh Division of Gastroenterology and Hepatology, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, California, USA.
Hepatology. 2024 Jul 1;80(1):102-118. doi: 10.1097/HEP.0000000000000717. Epub 2023 Dec 15.
Methionine adenosyltransferase alpha1 (MATα1) is responsible for the biosynthesis of S-adenosylmethionine in normal liver. Alcohol consumption enhances MATα1 interaction with peptidyl-prolyl cis-trans isomerase NIMA-interacting 1 (PIN1), which blocks MATα1 mitochondrial targeting, resulting in lower mitochondrial MATα1 content and mitochondrial dysfunction in alcohol-associated liver disease (ALD) in part through upregulation of cytochrome P450 2E1. Conversely, alcohol intake enhances SUMOylation, which enhances cytochrome P450 2E1 expression. MATα1 has potential SUMOylation sites, but whether MATα1 is regulated by SUMOylation in ALD is unknown. Here, we investigated if MATα1 is regulated by SUMOylation and, if so, how it impacts mitochondrial function in ALD.
Proteomics profiling revealed hyper-SUMOylation of MATα1, and prediction software identified lysine 48 (K48) as the potential SUMOylation site in mice (K47 in humans). Experiments with primary hepatocytes, mouse, and human livers revealed that SUMOylation of MAT1α by SUMO2 depleted mitochondrial MATα1. Furthermore, mutation of MATα1 K48 prevented ethanol-induced mitochondrial membrane depolarization, MATα1 depletion, and triglyceride accumulation. Additionally, CRISPR/CRISPR associated protein 9 gene editing of MATα1 at K48 hindered ethanol-induced MATα1-PIN1 interaction, degradation, and phosphorylation of MATα1 in vitro. In vivo, CRISPR/CRISPR associated protein 9 MATα1 K48 gene-edited mice were protected from ethanol-induced fat accumulation, liver injury, MATα1-PIN1 interaction, mitochondrial MATα1 depletion, mitochondrial dysfunction, and low S-adenosylmethionine levels.
Taken together, our findings demonstrate an essential role for SUMOylation of MATα1 K48 for interaction with PIN1 in ALD. Preventing MATα1 K48 SUMOylation may represent a potential treatment strategy for ALD.
甲硫氨酸腺苷转移酶 alpha1（MATα1）负责正常肝脏中 S-腺苷甲硫氨酸的生物合成。饮酒会增强 MATα1 与肽基脯氨酰顺反异构酶 NIMA 相互作用 1（PIN1）的相互作用，从而阻止 MATα1 向线粒体的靶向定位，导致线粒体 MATα1 含量降低和线粒体功能障碍，部分原因是细胞色素 P450 2E1 的上调。相反，饮酒会增强 SUMOylation，从而增强细胞色素 P450 2E1 的表达。MATα1 有潜在的 SUMOylation 位点，但在酒精相关性肝病（ALD）中 MATα1 是否受 SUMOylation 调节尚不清楚。在这里，我们研究了 MATα1 是否受 SUMOylation 调节，如果是，它如何影响 ALD 中的线粒体功能。
蛋白质组学分析显示 MATα1 的超 SUMOylation，预测软件鉴定出赖氨酸 48（K48）是小鼠中潜在的 SUMOylation 位点（人类为 K47）。原代肝细胞、小鼠和人肝实验表明，SUMO2 对 MAT1α 的 SUMOylation导致线粒体 MATα1 的消耗。此外，MATα1 K48 的突变阻止了乙醇诱导的线粒体膜去极化、MATα1 耗竭和甘油三酯积累。此外，CRISPR/Cas9 基因编辑 MATα1 的 K48 阻止了乙醇诱导的 MATα1-PIN1 相互作用、降解和 MATα1 的磷酸化。在体内，CRISPR/Cas9 相关蛋白 9 基因编辑的 MATα1 K48 基因编辑小鼠可防止乙醇诱导的脂肪积累、肝损伤、MATα1-PIN1 相互作用、线粒体 MATα1 耗竭、线粒体功能障碍和低 S-腺苷甲硫氨酸水平。
综上所述，我们的研究结果表明，MATα1 K48 的 SUMOylation对于与 ALD 中的 PIN1 相互作用至关重要。防止 MATα1 K48 SUMOylation 可能代表治疗 ALD 的一种潜在治疗策略。
