Methionine Adenosyltransferase Alpha1 in Alcoholic Liver Disease

酒精性肝病中的蛋氨酸腺苷转移酶 Alpha1

基本信息

批准号：
10376299
负责人：
Shelly Chi-Loo Lu
金额：
$ 39.38万
依托单位：
CEDARS-SINAI MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-05-15 至 2024-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10376299
关键词：
Affect Alcoholic Hepatitis Alcoholic Liver Diseases Anabolism Antioxidants Biological Biology CYP2E1 gene Catalytic Domain Cell Nucleus Cell physiology Co-Immunoprecipitations Competence Cytosol Data Development Enzymes Fibrosis Gene Expression Genes Glutathione Goals Health Heat shock proteins Heat-Shock Proteins 70 Heat-Shock Proteins 90 Hepatic Hepatocyte Hepatotoxicity Human Immunoprecipitation Impairment In Vitro Injury Isoenzymes Knock-out Knockout Mice Liver Mammals Mass Spectrum Analysis Mediating Methylation Mitochondria Mitochondrial Matrix Mitochondrial Proteins Molecular Molecular Chaperones Mus Normal Cell Pathogenesis Patients Peptidylprolyl Isomerase Play Process Proteins Recombinants Regulation Reporting Role S-Adenosylmethionine Source Sumoylation Pathway Testing Work cell type chronic liver disease dimer druggable target follow-up improved in vivo methionine adenosyltransferase mitochondrial dysfunction new therapeutic target novel prevent protein expression protein folding transcription factor

Affect Alcoholic Hepatitis Alcoholic Liver Diseases Anabolism Antioxidants Biological Biology CYP2E1 gene Catalytic Domain Cell Nucleus Cell physiology Co-Immunoprecipitations Competence Cytosol Data Development Enzymes Fibrosis Gene Expression Genes Glutathione Goals Health Heat shock proteins Heat-Shock Proteins 70 Heat-Shock Proteins 90 Hepatic Hepatocyte Hepatotoxicity Human Immunoprecipitation Impairment In Vitro Injury Isoenzymes Knock-out Knockout Mice Liver Mammals Mass Spectrum Analysis Mediating Methylation Mitochondria Mitochondrial Matrix Mitochondrial Proteins Molecular Molecular Chaperones Mus Normal Cell Pathogenesis Patients Peptidylprolyl Isomerase Play Process Proteins Recombinants Regulation Reporting Role S-Adenosylmethionine Source Sumoylation Pathway Testing Work cell type chronic liver disease dimer druggable target follow-up improved in vivo methionine adenosyltransferase mitochondrial dysfunction new therapeutic target novel prevent protein expression protein folding transcription factor

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项目摘要

ABSTRACT Methionine adenosyltransferase (MAT) is an essential cellular enzyme that catalyzes the formation of S- adenosylmethionine (SAMe), the principal biological methyl donor and in liver, precursor of the key antioxidant glutathione (GSH). In mammals, two different genes, MAT1A and MAT2A, encode for two homologous MAT catalytic subunits, α1 and α2, respectively. MAT1A is primarily expressed in normal liver. Majority of patients with chronic liver disease have decreased expression and activity of MAT1A-encoded isoenzymes. We found MAT1A expression and hepatic SAMe levels are reduced in alcoholic hepatitis patients. While MAT isoenzymes are widely acknowledged for catalyzing cytosolic SAMe biosynthesis, our recent works have uncovered highly novel aspects of their functions. In addition to cytosol and nucleus, our preliminary data indicate MATα1 is also present in the mitochondrial matrix to regulate mitochondrial function. This is important as we found hepatocytes lack the mitochondrial SAMe transporter SLC25A26. Using immunoprecipitation (IP) followed by mass spectrometry, we have identified many mitochondrial proteins and cytochrome P450 2E1 (CYP2E1) as MATα1-interacting proteins. Our preliminary data show that MATα1 negatively regulates CYP2E1 expression mainly at the protein level via methylation, which has not been reported. Importantly, MATα1 mitochondrial targeting is impaired in murine and human alcoholic liver disease (ALD) and we propose two novel mechanisms that may cooperate in causing this impairment. The current proposal tests the central hypothesis that MATα1 provides the SAMe source within the hepatocyte's mitochondrial matrix and impairment in MATα1 mitochondrial targeting in ALD plays a key role in the pathogenesis of ALD. The corollary hypothesis is that MATα1 maintains hepatocyte mitochondrial function in part by suppressing CYP2E1 expression. Here we follow up these novel findings in three specific aims: 1) examine how MATα1 targets the mitochondria and why its targeting is impaired in ALD. We will elucidate how MATα1 targets the mitochondria and mechanisms of its impaired targeting in ALD. We will test the novel hypothesis that this is due to 1) increased MATα1 sumoylation and 2) increased interaction of MATα1 with PIN1 (a peptidyl-prolyl cis- trans isomerase that recognizes a specific phosphorylated motif), 2) examine how MATα1 regulates CYP2E1 protein expression. We will examine how MATα1 regulates CYP2E1 protein stability at the molecular level and identify CYP2E1 residues and interacting proteins that participate in this process, 3) examine the role of mitochondrial MATα1 and MATα1-regulated CYP2E1 in ALD. We will test the novel hypothesis that preventing MATα1 sumoylation or interaction with PIN1 will protect against reduced mitochondrial MATα1 content and injury in ALD. We will also examine whether MATα1 will protect against ALD by methylating CYP2E1 at R379 to enhance its degradation. If successfully accomplished, these studies will change existing paradigms on MATα1 biology, CYP2E1 regulation and may uncover druggable targets for ALD.

抽象的蛋氨酸腺基转移酶（MAT）是一种必需的细胞酶，可催化S-的形成腺苷硫氨酸（相同），主要的生物甲基供体，在肝脏中，关键抗氧化剂的前体谷胱甘肽（GSH）。在哺乳动物中，两个不同的基因MAT1A和MAT2A编码两个同源垫子催化亚基α1和α2。 MAT1A主要在正常肝脏中表达。大多数患者慢性肝病降低了MAT1A编码的同工酶的表达和活性。我们发现在酒精性肝炎患者中，MAT1A表达和肝相同水平降低。垫子同工酶因催化胞质相同的生物合成而被广泛认可，我们最近的作品已有发现了其功能的高度新颖方面。除了细胞质和核之外，我们的初步数据表明MATα1也存在于线粒体基质中以调节线粒体功能。这很重要正如我们发现肝细胞缺乏线粒体相同的转运蛋白SLC25A26。使用免疫沉淀（IP）其次是质谱法，我们确定了许多线粒体蛋白和细胞色素P450 2E1 （CYP2E1）作为MATα1相互作用蛋白。我们的初步数据表明，MATα1对调节进行负调节 CYP2E1的表达主要通过甲基化在蛋白质水平上，尚未报道。重要的是， MATα1线粒体靶向在鼠和人类酒精肝病（ALD）中受到损害，我们建议两种新型机制可能会导致这种障碍。当前的提案测试中央假设MATα1在肝细胞的线粒体基质中提供了相同的来源 MATα1线粒体靶向ALD的损伤在ALD的发病机理中起关键作用。这推论假设是MATα1通过抑制部分保持肝细胞线粒体功能 CYP2E1表达。在这里，我们在三个特定目的中跟进这些新发现：1）检查Matα1如何靶向线粒体，以及为什么其靶向在ALD中受到损害。我们将阐明MATα1的目标线粒体及其在ALD中靶向的机制。我们将测试新的假设，即由于1）MATα1sumoylation的增加和2）MATα1与PIN1的相互作用增加（肽基 - 丙酰基CIS- 识别特定光磷酸化基序的反式异构酶，2）检查MATα1如何调节CYP2E1 蛋白表达。我们将研究MATα1如何调节分子水平的CYP2E1蛋白稳定性并确定参与此过程的CYP2E1保留和相互作用的蛋白质，3）检查线粒体MATα1和MATα1调节的CYP2E1在ALD中。我们将测试一个新的假设防止MATα1sumoylation或与PIN1相互作用将预防减少线粒体MATα1 ALD的内容和伤害。我们还将检查MATα1是否会通过甲基化预防ALD R379的CYP2E1增强其降解。如果成功完成，这些研究将改变现有 MATα1生物学，CYP2E1调节的范例，并可能发现ALD的可药物靶标。