Role of hepatic Mettl14 pathways in liver metabolism and body metabolic homeostasis

肝脏Mettl14通路在肝脏代谢和机体代谢稳态中的作用

• 批准号: 10621821
• 负责人: LIANGYOU RUI
• 金额: $ 39万
• 依托单位: UNIVERSITY OF MICHIGAN AT ANN ARBOR
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10621821
• 关键词: Ablation; Adult; Amino Acids; Attenuated; Binding; Binding Proteins; Catalytic Domain; Cell physiology; Complex; Development; Diabetes Mellitus; Disease; Embryo; Embryo Deaths; Fatty Acids; Fatty Liver; Genetic; Genetic Transcription; Genomics; Glucagon; Gluconeogenesis; Glucose; Glucose Intolerance; Health; Hepatic; Hepatocyte; High Fat Diet; Homeostasis; Hyperglycemia; Injury; Insulin; Insulin Resistance; Knockout Mice; Lipids; Liver; Liver diseases; Mediating; Mediator; Messenger RNA; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolic dysfunction; Metabolic hormone; Methylation; Methyltransferase; Modeling; Modification; Morbidity - disease rate; Mus; Non-Insulin-Dependent Diabetes Mellitus; Nuclear Export; Obesity; Obesity associated liver disease; Organ; Outcome; Pathway interactions; Post-Transcriptional RNA Processing; Production; Protein Biosynthesis; Proteins; RNA; RNA Splicing; RNA metabolism; RNA methylation; RNA-Binding Proteins; RNA-Protein Interaction; Role; Signal Pathway; Signal Transduction; Slice; Transcript; Transcriptional Regulation; epigenetic regulation; epitranscriptomics; fatty liver disease; genetic information; glucose metabolism; glucose production; hepatic gluconeogenesis; improved; lipid biosynthesis; lipid metabolism; liver ablation; liver function; liver metabolism; mRNA Decay; mRNA Precursor; molecular targeted therapies; mortality; non-alcoholic fatty liver disease; novel; oxidation; programs; repaired; response; trafficking; transcriptome sequencing; translational genetics

Messenger RNA mediates translation of genetic information into protein synthesis and cell functions. Levels of translationally-competent mRNA are determined by RNA transcription, post-transcriptional modifications, and RNA interactions with proteins. Genetic and epigenetic regulations of transcription have been extensively investigated; by contrast, there is a gap in our understanding of mRNA modifications, RNA-protein interactions, and their impacts on cellular responses. N6-methyladenosine (m6A) is the predominant mRNA modification, and is catalyzed by a Mettl3 (catalytic subunit)/Mettl14 (structural subunit) methyltransferase complex. M6A motif is recognized by and bound to Ythdc1 or related RNA-binding proteins, which in turn control pre-mRNA splicing, nuclear export, intracellular localization, decay, and/or translational efficiency of target mRNAs. Global deletion of Mettl3, Mettl14, or Ythdc1 results in embryonic death, revealing the essential role of these epitranscriptomic mediators in development and survival. Liver is an essential metabolic organ. Liver disease, including nonalcoholic fatty liver disease (NAFLD) and metabolic dysfunctions, is a main cause for mortality and morbidity. However, Mettl14/Ythdc1-based epitranscriptomic programs have not been explored in the liver. In the preliminary study, we generated adult-onset, hepatocyte-specific Mettl14 and Ythdc1 knockout mice. Ablation of hepatic Mettl14 attenuated high fat diet (HFD)-induced hyperglycemia, glucose intolerance, and liver steatosis. Likewise, hepatocyte-specific deletion of Ythdc1 also improved glucose metabolism in HFD-fed mice. In liver slice cultures, Mettl14 deficiency blunted glucagon-stimulated liver glucose production. RNA-seq analysis showed that deletion of hepatic Mettl14 changed levels of many liver mRNA transcripts encoding proteins involved in glucose/lipid metabolism and signaling pathways. Based on these results, we hypothesize that Mettl14 mediates m6A methylation in mRNAs encoding mediators/modulates for hepatic gluconeogenesis, lipogenesis, and related signaling pathways. Ythdc1 binds to m6A motif, and controls pre-mRNA splicing, nuclear export, and/or degradation of a subset of Mettl14 substrates. Moreover, obesity-related factors increase expression and stability of hepatic Mettl14 and Ythdc1, thereby eliciting Mettl14/Ythdc1-based epitranscriptomic reprogramming of liver metabolism. Mettl14/m6A/Ythdc1-elicited epitranscriptomic reprogramming provides a new mechanism underlying obesity-associated NAFLD and type 2 diabetes. Aim 1 determines whether hepatic Mettl14 directly promotes liver glucose production and liver steatosis by an epitranscriptomic mechanism. Aim 2 determines whether Ythdc1 mediates the metabolic action of Mettl14 in the liver. Aim 3 determines whether Mettl14/Ythdc1-elicited epitranscriptomic reprogramming mediates obesity- associated liver disease. The outcomes of this project are expected to establish a new Mett14/Ythdc1-based epitranscriptomic reprogramming paradigm governing liver metabolism in health and disease.

Messenger RNA介导遗传信息转化为蛋白质合成和细胞功能。翻译能力的mRNA水平由RNA转录，转录后修饰和与蛋白质的RNA相互作用确定。转录的遗传和表观遗传法规已得到广泛研究。相比之下，我们对mRNA修饰，RNA - 蛋白质相互作用及其对细胞反应的影响存在差距。 N6-甲基丙氨酸（M6A）是主要的mRNA修饰，并由Mettl3（催化亚基）/Mettl14（结构亚基）甲基转移酶复合物催化。 M6A基序是通过YTHDC1或相关的RNA结合蛋白识别并结合的，后者反过来控制目标mRNA的MRNA剪接，核输出，细胞内定位，衰减和/或转化效率。 METTL3，METTL14或YTHDC1的全球删除导致胚胎死亡，揭示了这些表演体介体在发育和生存中的重要作用。肝脏是必不可少的代谢器官。肝病，包括非酒精性脂肪肝病（NAFLD）和代谢功能障碍，是死亡率和发病率的主要原因。但是，肝脏尚未在肝脏中探索基于Mettl14/YTHDC1的表面参考程序。在初步研究中，我们产生了成人发作，肝细胞特异性METTL14和YTHDC1敲除小鼠。肝METTL14的消融减弱了高脂肪饮食（HFD）诱导的高血糖，葡萄糖不耐症和肝脂肪变性。同样，YTHDC1的肝细胞特异性缺失也改善了HFD喂养的小鼠的葡萄糖代谢。在肝切片培养物中，METTL14缺乏钝化胰高血糖素刺激的肝葡萄糖产生。 RNA-seq分析表明，肝METTL14的缺失改变了编码涉及葡萄糖/脂质代谢和信号通路的许多肝mRNA转录物的水平。基于这些结果，我们假设METTL14介导了编码介质/调节剂的mRNA中的M6A甲基化，以进行肝糖生成，脂肪生成和相关的信号传导途径。 YTHDC1与M6A基序结合，并控制METTL14底物子集的MRNA剪接，核输出和/或降解。此外，与肥胖相关的因子增加了肝METTL14和YTHDC1的表达和稳定性，从而诱导了基于肝脏代谢的基于Mettl14/YTHDC1的表达体的重新编程。 Mettl14/M6A/YTHDC1引用的表面见面组重编程提供了一种与肥胖相关的NAFLD和2型糖尿病的新机制。 AIM 1确定肝METTL14是否直接通过表面参考机制直接促进肝葡萄糖产生和肝脏脂肪变性。 AIM 2确定YTHDC1是否介导了METTL14在肝脏中的代谢作用。 AIM 3确定METTL14/YTHDC1引用的表面转录组重编程是否介导了肥胖与肝脏疾病。预计该项目的结果将建立一种新的Mett14/YTHDC1基于健康和疾病中肝脏代谢的范式的表相关重编程范式。