Mechanisms and therapeutic potential of blocking the mitochondrial Mg2+ channel Mrs2 in obesity and NAFLD

阻断线粒体 Mg2 通道 Mrs2 在肥胖和 NAFLD 中的机制和治疗潜力

• 批准号: 10679847
• 负责人: Joseph A. Baur
• 金额: $ 55.8万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-04-01 至 2027-01-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10679847
• 关键词: Ablation; Address; Adipocytes; Adipose tissue; Adopted; Animals; Biochemical; Biochemistry; Bioenergetics; Biological; Body Composition; Body Weight; Brown Fat; CRISPR/Cas technology; Cardiovascular Diseases; Cell physiology; Cells; Chronic Kidney Failure; Citrates; Clinical; Data; Detection; Development; Diabetes Mellitus; Disease; Disease Progression; Disease model; Divalent Cations; Energy Metabolism; Eukaryota; Event; Failure; Fatty Liver; Fatty acid glycerol esters; Functional disorder; Gene Expression Profile; Genetic; Glucose; Glycolysis; HIF1A gene; Health; Hepatic; Hepatocyte; Homeostasis; Hyperglycemia; Impairment; In Vitro; Intervention; Ion Channel; Knockout Mice; Ligands; Link; Lipids; Liver; Liver Mitochondria; Magnesium; Malignant Neoplasms; Measures; Mediating; Metabolic; Metabolic Diseases; Metabolic Pathway; Metabolism; Migraine; Mitochondria; Mitochondrial RNA; Modeling; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathologic Processes; Pathway interactions; Patients; Phenotype; Physiological; Physiology; Plasma; Play; Pre-Eclampsia; Prevalence; Public Health; Quality Control; RNA Splicing; Regulation; Role; Sepsis; Signal Transduction; Stress; Structure; Testing; Therapeutic; Triglycerides; Weight Gain; biophysical techniques; blood glucose regulation; candidate identification; comorbidity; diet-induced obesity; dietary; dietary control; experimental study; fatty acid oxidation; feeding; fibroblast growth factor 21; genetic approach; genetic regulatory protein; glucose metabolism; glucose production; in vivo; innovation; insight; interest; lipid biosynthesis; lipid metabolism; liver function; liver metabolism; mouse model; nervous system disorder; non-alcoholic fatty liver disease; novel therapeutic intervention; obesity prevention; oxidation; pharmacologic; preservation; prevent; respiratory; restoration; small molecule; transcriptome sequencing; treatment strategy; uptake; western diet

ABSTRACT Aberrant hepatic glucose and lipid metabolism is a feature of several prevalent metabolic disorders, including obesity, type 2 diabetes (T2DM) and nonalcoholic fatty liver disease (NAFLD). Increased hepatic glucose production directly contributes to hyperglycemia in patients with T2DM, and hepatic steatosis is the defining feature of NAFLD. The increased prevalence of T2DM and NAFLD present a significant threat to public health, and treatment strategies that address the underlying pathological processes are urgently needed. Although Ca2+ signaling in metabolic disease is emerging, the potential reciprocal role of Mg2+ dynamics on mitochondrial bioenergetics is much less understood and is the focus of the current proposal. In preliminary studies, we generated a global KO model of the mitochondrial Mg2+ transporter Mrs2 using CRISPR/Cas9 and examined the impact on hepatic metabolism (Daw et al Cell 2020). Interestingly, loss of Mrs2 impairs mMg2+ uptake and prevents hepatic steatosis in vivo. This is associated with increased mitochondrial respiratory capacity in hepatocytes and markedly enhanced browning of white adipose tissue, indicative of increased capacity for energy expenditure. Using innovative, unbiased RNA-seq, animal physiology studies, molecular, cell biological, biochemistry and biophysical approaches, we have identified candidate pathways linking Mrs2-mediated mMg2+ uptake to mitochondrial suppression of OXPHOS and fatty acid oxidation under WD. Remarkably, the elevation of de novo lipogenesis precursor citrate is blunted in Mrs2 KO mice and thus controls diet induced obesity. Based on these preliminary data, we hypothesize that Mrs2-mediated mMg2+ uptake is a key determinant of mitochondrial bioenergetic failure in the liver during disease progression, and that mitigating excess mMg2+ uptake using a small molecule blocker of the Mrs2 channel activity will prevent the development of NAFLD through restoration of signaling and mitochondrial bioenergetics. The overall aim of the current proposal is to identify molecular signals that are controlled by mMg2+ dynamics, and their impact on bioenergetics and mitochondrial quality control, and to describe the molecular mechanisms linking Mrs2 to key hepatic metabolic pathways that are dysregulated in metabolic diseases. Using a combination of integrative in vitro and in vivo approaches, we will perform mechanistic studies to determine the impact of disrupted intracellular Mg2+ signals on mitochondrial function, hepatic lipid and glucose metabolism, whole-body energy homeostasis, and the progression of NAFLD. Given these preliminary findings, in Specific Aim 1 of the proposal we will employ our unique mouse model to examine the role of Mrs2 and mMg2+ uptake on mitochondrial function in hepatocytes and will determine the impact of impaired mMg2+ uptake on hepatic and whole-body glucose and lipid metabolism. In Specific Aim 2, we will investigate the role of citrate in Hif-1α dependent signaling that is altered in Mrs2 KO, which ultimately restores mitochondrial energetics and quality control. Finally, in Specific Aim 3, we will use both genetic and pharmacologic interventions to evaluate the significance of MRS2 in NAFLD models.

抽象的 肝脏葡萄糖和脂质代谢异常是几种常见代谢性疾病的一个特征，包括 肥胖、2 型糖尿病 (T2DM) 和非酒精性脂肪肝 (NAFLD) 肝糖水平升高。 产生直接导致 T2DM 患者高血糖，而肝脂肪变性是其定义 T2DM 和 NAFLD 患病率的增加对公众健康构成重大威胁， 迫切需要解决潜在病理过程的治疗策略。 代谢疾病中的信号传导正在兴起，Mg2+动力学对线粒体的潜在相互作用 生物能量学的了解要少得多，并且是当前提案的重点，我们在初步研究中。 使用 CRISPR/Cas9 生成了线粒体 Mg2+ 转运蛋白 Mrs2 的全局 KO 模型，并检查了 对肝脏代谢的影响（Daw et al Cell 2020），Mrs2 的缺失会损害 mmg2+ 的吸收和吸收。 预防体内肝脂肪变性，这与线粒体呼吸能力的增加有关。 肝细胞和白色脂肪组织的褐变显着增强，这是代谢能力增加的指标 能量消耗。使用创新、公正的 RNA-seq、动物生理学研究、分子、细胞生物学， 生物化学和生物物理方法，我们已经确定了连接 Mrs2 介导的 mMg2+ 的候选途径 WD 下 OXPHOS 和脂肪酸氧化的线粒体抑制的摄取显着升高。 在 Mrs2 KO 小鼠中，从头脂肪生成前体柠檬酸的活性减弱，从而控制饮食诱导的肥胖。 根据这些初步数据，我们认为 Mrs2 介导的 mmg2+ 摄取是 疾病进展期间肝脏线粒体生物能衰竭，以及减轻过量的 mmg2+ 使用 Mrs2 通道活性的小分子阻滞剂摄取可预防 NAFLD 的发展 通过恢复信号传导和线粒体生物能量学当前提案的总体目标是 识别由 mMg2+ 动力学控制的分子信号及其对生物能学和 线粒体质量控制，并描述连接 Mrs2 与关键肝脏代谢的分子机制 结合体外和体内的综合治疗代谢疾病中失调的途径。 方法，我们将进行机制研究，以确定细胞内 Mg2+ 信号中断的影响 线粒体功能、肝脏脂质和葡萄糖代谢、全身能量稳态以及 鉴于 NAFLD 的进展，在该提案的具体目标 1 中，我们将采用我们的研究成果。 独特的小鼠模型，用于检查 Mrs2 和 mMg2+ 摄取对肝细胞线粒体功能的作用 并将确定 mMg2+ 摄取受损对肝脏和全身葡萄糖和脂质代谢的影响。 在具体目标 2 中，我们将研究柠檬酸盐在 Mrs2 KO 中改变的 Hif-1α 依赖性信号传导中的作用， 最终恢复线粒体能量和质量控制。最后，在具体目标 3 中，我们将同时使用两者。 遗传和药理学干预措施评估 MRS2 在 NAFLD 模型中的重要性。