Role of the mitochondrial calcium uniporter in brown fat physiology

线粒体钙单向转运蛋白在棕色脂肪生理学中的作用

• 批准号: 9096647
• 负责人: Daniel Robert Flicker
• 金额: $ 2.93万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9096647
• 关键词: Adipocytes; Adrenergic Agents; Affect; Albumins; Alleles; Animals; Attention; Bioenergetics; Biological; Biological Assay; Biology; Brown Fat; Burn injury; C57BL/6 Mouse; Calcium; Calcium Signaling; Catecholamines; Cell Culture Techniques; Cell Death; Cell Line; Cells; Citric Acid Cycle; Clinic; Clinical; Complement; Couples; Data; Defect; Development; Diet; Discipline; Dissection; Energy Metabolism; Event; Exhibits; Exons; Genes; Genetic; Health; Homeostasis; Hormonal; Human; Individual; Institution; Insulin Resistance; Laboratories; Length; Link; Lipids; Liver; Measures; Metabolic; Metabolic Diseases; Metabolism; Mitochondria; Molecular; Mus; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Organ; Paper; Phenotype; Physiology; Play; Positron-Emission Tomography; Postdoctoral Fellow; Predisposition; Process; Production; RNA Interference; Reactive Oxygen Species; Reagent; Regulation; Reporting; Research; Research Personnel; Resources; Respiration; Risk Factors; Role; Scientist; Series; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Skeletal Muscle; Stimulus; Stress; Syndrome; Technical Expertise; Testing; Therapeutic; Tissues; Training; United States; Work; calcium uniporter; cell type; density; diabetic; economic impact; educational atmosphere; global health; impaired glucose tolerance; insight; insulin sensitivity; interest; knock-down; knockout animal; lipid metabolism; novel; oxidation; precursor cell; programs; promoter; public health relevance; recombinase; response; sensor; skills; small hairpin RNA; therapeutic target; uptake

 DESCRIPTION (provided by applicant): Insulin resistance and type 2 diabetes (T2D) represent a global health crisis of potentially disastrous economic impact. In the United States alone, over one hundred million individuals suffer from obesity, the leading risk factor for pre-diabetic and diabetic syndromes. Recently, there has been widespread interest in treating obesity, T2D, and associated metabolic disorders by enhancing the activity of brown fat, a tissue capable of burning excess lipid stores via uncoupled ß-oxidation. At present, however, the regulation of brown fat metabolism is incompletely understood, and it is unclear how this tissue exerts its therapeutically promising effects on systemic energy homeostasis. This proposal aims to advance the understanding of fundamental brown fat physiology by interrogating the role of the mitochondrial calcium uniporter, a channel whose molecular identity was recently elucidated by the applicant's laboratory. The uniporter couples ATP production to cellular energy demand, and may play a key role in fuel switching through its ability to regulate TCA cycle flux and anaplerosis. The uniporter is linked to adrenergic signaling in multiple tissues and supports peak bioenergetics in skeletal muscle, a close developmental and metabolic relative of brown fat; in addition, uniporter current density in brown fat mitochondria i among the highest measured in any tissue. The uniporter is therefore a promising candidate to regulate brown fat metabolism in response to hormonal stimuli. The applicant will pursue the core hypothesis that the uniporter plays a central role in brown fat physiology in two complementary but not codependent specific aims. In Aim 1, the uniporter's pore- forming subunit (MCU) will be ablated in immortalized brown adipocytes, and the resulting cell lines will be analyzed for defects in bioenergetics, metabolism, stress signaling, and calcium dynamics. Exciting preliminary data indicate that brown adipocytes lacking MCU exhibit blunted catecholamine-stimulated respiration; these results will be rigorously validated and dissected mechanistically. In Aim 2, MCU will be deleted in brown fat in mice, and the resulting animals will be assayed for altered energy expenditure and brown fat activity, cold intolerance, increased susceptibility to diet-induced obesity, and insulin resistance. The applicant's laboratory has already generated mice harboring a conditional MCU allele that can be used to ablate uniporter activity in a tissue-specific manner. By establishing a role for the uniporter in brown fat, this wrk will yield foundational insights into the physiology of this tissue, laying the groundwork for its clinical exploitation to ameliorate T2D and obesity. The work will also complement the proposed training plan, enabling the applicant to develop into a mature, rigorous scientist with the abilityto communicate across a variety of topical disciplines.

 描述（由申请人提供）：胰岛素抵抗和 2 型糖尿病 (T2D) 是一场可能造成灾难性经济影响的全球健康危机，仅在美国就有超过一亿人患有肥胖症，这是糖尿病前期的主要危险因素。最近，人们对通过增强棕色脂肪的活性来治疗肥胖、T2D 和相关代谢紊乱产生了广泛的兴趣，棕色脂肪是一种能够通过解偶联燃烧过量脂质储存的组织。然而，目前，棕色脂肪代谢的调节尚不完全清楚，并且尚不清楚它如何对组织发挥对全身能量稳态的治​​疗作用。该提案旨在通过探究棕色脂肪的基本生理学来促进对基本棕色脂肪生理学的理解。线粒体钙单向转运蛋白的作用，申请人的实验室最近阐明了其分子特性。单向转运蛋白将 ATP 产生与细胞能量需求结合起来，并且可能在通过其进行的燃料转换中发挥关键作用。调节 TCA 循环通量和回补的能力与多个组织中的肾上腺素信号传导有关，并支持骨骼肌中的峰值生物能，这是棕色脂肪的密切发育和代谢亲戚；此外，棕色脂肪线粒体中的单向转运蛋白电流密度也是其中之一。因此，单向转运蛋白是调节棕色脂肪代谢以响应激素刺激的有前途的候选者，申请人将追求单向转运蛋白在棕色脂肪中发挥核心作用的核心假设。在目标 1 中，单向转运蛋白的成孔亚基 (MCU) 将在永生化棕色脂肪细胞中被消除，并且将分析所得细胞系的生物能学、代谢、应激信号传导等方面的缺陷。令人兴奋的初步数据表明，缺乏 MCU 的棕色脂肪细胞表现出儿茶酚胺刺激的呼吸减弱；这些结果将得到严格的验证和机械解剖。在目标 2 中，将删除小鼠棕色脂肪中的 MCU，并对所得动物进行能量消耗和棕色脂肪活性改变、寒冷不耐受、对饮食引起的肥胖的易感性增加以及胰岛素抵抗的分析。生成的小鼠含有条件性 MCU 等位基因，可用于以组织特异性方式消除单向转运蛋白活性。通过确定单向转运蛋白在棕色脂肪中的作用，这项工作将为生理学提供基础见解。这项工作也将补充拟议的培训计划，使申请人能够发展成为一名成熟、严谨的科学家，具有跨多个主题学科进行交流的能力。