The Role of Gm4951 in Nonalcoholic Fatty Liver Disease

Gm4951 在非酒精性脂肪肝中的作用

• 批准号: 10339213
• 负责人: Zhao Zhang
• 金额: $ 36.08万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10339213
• 关键词: Alleles; Body Weight; Characteristics; Cirrhosis; Coupling; Data; Development; Diet; Disease; Disease model; Energy Metabolism; Enzymes; Family; Fatty Liver; Future; Genes; Genetic; Genetic Screening; Genetic Transcription; Genetic Variation; Germ-Line Mutation; Goals; Guanosine Triphosphate Phosphohydrolases; Health; Hepatic; Hepatocyte; High Fat Diet; Homologous Gene; Human; Hydroxysteroids; In Vitro; Insulin; Insulin Resistance; Interferon Type II; Interferons; Knock-in Mouse; Knock-out; Knowledge; Lipids; Liver; Location; LoxP-flanked allele; Mass Spectrum Analysis; Meiosis; Metabolic; Missense Mutation; Molecular; Mus; Mutant Strains Mice; Mutation; Names; Obesity; Oxidoreductase; Pathogenesis; Pathway interactions; Pattern; Phenotype; Physiological; Prevalence; Primary carcinoma of the liver cells; Process; Promoter Regions; Proteins; Proteomics; Public Health; Regulation; Research; Role; Series; Severities; Slice; Testing; Time; Tissues; Transcriptional Regulation; Translating; Weight Gain; Work; adenoviral-mediated; chronic liver disease; combat; dietary; disease phenotype; experimental study; fatty acid oxidation; glucose metabolism; inducible gene expression; insight; lipid biosynthesis; lipid metabolism; member; mouse model; mutant; new therapeutic target; non-alcoholic fatty liver disease; nonalcoholic steatohepatitis; novel strategies; novel therapeutic intervention; overexpression; oxidation; prevent; screening; transcription factor

PROJECT SUMMARY Nonalcoholic fatty liver disease (NAFLD) is becoming a global human health problem. Our long-term goal is to understand molecular mechanisms of NAFLD, and to translate this knowledge into novel therapeutic strategies. Due to the physiologic similarities between humans and mice, and the propensity of mice to develop a disease closely mimicking NAFLD when fed a high fat diet (HFD), mice have provided us with fundamental insights into NAFLD pathogenesis. In humans and mice, genetic variation influences the rate and severity of hepatosteatosis under a given set of environmental conditions. To identify genes that influence the process, we utilized unbiased forward genetic screening and highly automated meiotic mapping to identify mutations that cause NAFLD in mice sensitized by a HFD. Two semi-dominant missense alleles of predicted gene 4951 (Gm4951), named Oily and Carboniferous, were detected in this screen. As distinct from most NAFLD mutants that are associated with obesity, our preliminary data showed that Gm4951 deficient mice had dramatically increased hepatic lipid accumulation without a concomitant increase of body weight on a HFD. Gm4951 was highly expressed in hepatocytes. Knockout of Gm4951 increased lipid content and overexpression of Gm4951 decreased lipid content of primary hepatocytes in vitro, suggesting hepatocyte-intrinsic regulation of lipid content. Gm4951 knockout livers showed decreased expression of lipid oxidation genes. Mass spectrometry analysis of endogenous GM4951 interacting proteins revealed interaction with lipid droplet protein Hydroxysteroid 17β- dehydrogenase 13 (HSD17B13) and lipid oxidation enzymes. Moreover, the transcription of Gm4951 in hepatocytes was activated by interferon gamma (IFN-γ), which effectively decreased lipid content, much as when GM4951 was overexpressed. These results led to our central hypothesis that GM4951 is critical for promoting lipid oxidation, and limits hepatic lipid accumulation. To test this hypothesis, we propose to pursue three Specific Aims. Aim 1 will further investigate the development of NAFLD in GM4951 deficient mice. Aim 2 will determine the precise mechanistic role of GM4951 in regulating lipid metabolism. Aim 3 will study the transcriptional regulation of Gm4951, including the liver-specific expression pattern and the inducible expression by IFN-γ. Understanding how to activate GM4951 and what’s the human homolog of GM4951 would offer approaches to preventing or treating NAFLD. These will be studied in Aim 3 as well. The NAFLD phenotype caused by GM4951 deficiency is fundamentally distinct from the classic obesity-associated NAFLD mouse models. GM4951 is specifically expressed in the liver and operates there to limit lipid accumulation. Thus, finding ways to activate GM4951 will provide a new means of reducing hepatic lipid content. Completion of the proposed work will suggest new therapeutic targets to combat NAFLD.

项目概要 非酒精性脂肪肝（NAFLD）正在成为全球人类健康问题。我们的长期目标是 了解 NAFLD 的分子机制，并将这些知识转化为新的治疗策略。 由于人类和小鼠之间的生理相似性，以及小鼠患疾病的倾向 当喂食高脂肪饮食（HFD）时，小鼠与 NAFLD 非常相似，为我们提供了基本的见解 NAFLD 发病机制。在人类和小鼠中，遗传变异影响肝脂肪变性的发生率和严重程度 在给定的环境条件下。为了识别影响该过程的基因，我们利用了无偏见的 正向遗传筛选和高度自动化减数分裂图谱，以识别导致小鼠 NAFLD 的突变 由 HFD 致敏。预测基因 4951 (Gm4951) 的两个半显性错义等位基因，分别命名为 Oily 和 在此筛中检测到石炭系。与大多数 NAFLD 突变体不同的是， 肥胖，我们的初步数据显示，Gm4951缺陷小鼠的肝脂质显着增加 在 HFD 上积累而不伴随体重增加。 Gm4951 高表达于 肝细胞。 Gm4951 的敲除增加了脂质含量，而 Gm4951 的过表达则降低了脂质含量 体外原代肝细胞的含量，表明肝细胞对脂质含量的内在调节。 GM4951 敲除肝脏显示脂质氧化基因的表达减少。质谱分析 内源性 GM4951 相互作用蛋白揭示了与脂滴蛋白 Hydroxysteroid 17β- 的相互作用 脱氢酶 13 (HSD17B13) 和脂质氧化酶。此外，Gm4951 的转录 肝细胞被干扰素γ（IFN-γ）激活，有效降低脂质含量，就像当 GM4951 过度表达。这些结果得出我们的中心假设：GM4951 对于促进 脂质氧化，并限制肝脏脂质积累。为了检验这一假设，我们建议追求三个具体目标 目标。目标 1 将进一步研究 GM4951 缺陷小鼠中 NAFLD 的发展。目标 2 将决定 GM4951 在调节脂质代谢中的精确机制作用。目标 3 将研究转录 Gm4951 的调节，包括肝脏特异性表达模式和 IFN-γ 的诱导表达。 了解如何激活 GM4951 以及 GM4951 的人类同源物是什么将为我们提供方法 预防或治疗 NAFLD。这些也将在目标 3 中进行研究。 GM4951引起的NAFLD表型 缺乏症与经典的肥胖相关 NAFLD 小鼠模型有着根本的区别。 GM4951是 在肝脏中特异性表达并在肝脏中发挥作用以限制脂质积累。因此，寻找激活的方法 GM4951将提供一种降低肝脏脂质含量的新手段。完成拟议的工作将 提出对抗 NAFLD 的新治疗靶点。