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.

摘要 肝脏葡萄糖和脂质代谢异常是几种常见代谢紊乱的特征，包括 肥胖、2型糖尿病（T2 DM）和非酒精性脂肪肝（NAFLD）。肝葡萄糖升高 产生直接导致T2 DM患者的高血糖症，肝脂肪变性是T2 DM的定义。 NAFLD的特征。T2 DM和NAFLD患病率的增加对公共卫生构成了重大威胁， 并且迫切需要解决潜在病理过程的治疗策略。虽然Ca 2 + 在代谢疾病的信号是新兴的，潜在的相互作用的Mg 2+动力学对线粒体 对生物能量学的了解要少得多，这是目前提案的重点。在初步研究中，我们 使用CRISPR/Cas9生成了线粒体Mg 2+转运蛋白Mrs 2的全局KO模型，并检查了 对肝脏代谢的影响（Daw et al Cell 2020）。有趣的是，Mrs 2的缺失损害mMg 2+摄取， 防止体内肝脂肪变性。这与线粒体呼吸能力的增加有关， 肝细胞和明显增强的白色脂肪组织的布朗宁，表明增加的能力， 能量消耗使用创新的，无偏见的RNA-seq，动物生理学研究，分子，细胞生物学， 通过生物化学和生物物理方法，我们已经确定了Mrs 2介导的mMg 2 + 摄取到线粒体抑制OXPHOS和脂肪酸氧化。值得注意的是， 在Mrs 2 KO小鼠中，新生脂肪生成前体柠檬酸盐的浓度降低，从而控制饮食诱导的肥胖。基于 根据这些初步数据，我们假设Mrs 2介导的mMg 2+摄取是 疾病进展期间肝脏中线粒体生物能量衰竭，以及减轻过量mMg 2 + 使用Mrs 2通道活性的小分子阻断剂的摄取将防止NAFLD的发展 通过恢复信号和线粒体生物能量学。本提案的总体目标是 识别由mMg 2+动力学控制的分子信号，及其对生物能量学的影响， 线粒体质量控制，并描述Mrs 2与关键肝代谢的分子机制 代谢疾病中失调的途径。使用体外和体内整合的组合 方法，我们将进行机制研究，以确定破坏细胞内Mg 2+信号的影响 对线粒体功能、肝脏脂质和葡萄糖代谢、全身能量稳态以及 NAFLD的进展。鉴于这些初步研究结果，在建议的具体目标1中，我们将采用 独特的小鼠模型，用于检查Mrs 2和mMg 2+摄取对肝细胞线粒体功能的作用 并将确定受损的mMg 2+摄取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Mrs 2 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 遗传和药理学干预，以评估MRS 2在NAFLD模型中的意义。