Recruitment of skeletal muscle based non-shivering thermogenesis in health and di

健康和疾病中基于非颤抖产热的骨骼肌募集

• 批准号: 8631829
• 负责人: Muthu Periasamy
• 金额: $ 33.39万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-17 至 2018-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8631829
• 关键词: ATP Hydrolysis; Acute; Adult; Affect; Animals; Binding; Binding Sites; Brown Fat; C-terminal; Ca(2+)-Transporting ATPase; Calcineurin; Calcium; Calmodulin; Chimera organism; Diet; Elements; Energy Metabolism; Fatty Acids; Fatty acid glycerol esters; Generations; Genetic; Goals; Health; Heating; Human; Indium; Knockout Mice; Laboratories; Lead; Link; Mammals; Mediating; Metabolic; Metabolism; Molecular; Mus; Muscle; Muscle Contraction; Obesity; PPAR Pathway; Phosphotransferases; Play; Proteins; Pump; Recruitment Activity; Regulation; Reporting; Research; Rest; Rodent; Role; Signal Pathway; Site; Skeletal Muscle; Testing; Therapeutic; Thermogenesis; Thinking; Time; Transmembrane Domain; Up-Regulation; Weight; base; energy balance; feeding; muscle metabolism; mutant; natural hypothermia; novel; obesity treatment; overexpression; phospholamban; protein protein interaction; public health relevance; research study; sarcolipin

SUMMARY Increasing evidence suggest that in addition to brown adipose tissue (BAT), skeletal muscle is an important site for Nonshivering thermogenesis (NST). Although several studies have suggested that SR Ca2+ cycling may play a role in muscle thermogenesis, the molecular details were not known. Studies from our laboratory and others have shown that Sarcolipin (SLN), a regulator of SR Ca2+ ATPase (SERCA), can bind to SERCA in the presence of Ca2+ and promote uncoupling of SERCA and increase ATP hydrolysis. In the presence of SLN, SERCA becomes inefficient; transporting less than 2 mol Ca2+ per mol ATP, thereby increasing ATP hydrolysis and heat production. These studies hinted that SLN could play a role in muscle thermogenesis .To define the relevance of SLN in muscle, we took a genetic approach and recently showed that loss of SLN predisposes mice to develop hypothermia during acute cold exposure but reintroduction of SLN in the Sln-/- background fully restored muscle-based thermogenesis. In addition, when Sln-/- mice when fed on high fat diet (HFD) gained significantly more weight than WT controls, whereas WT mice fed on HFD were less obese but showed significant upregulation of SLN (3-4 fold) suggesting that SLN is recruited in diet induced thermogenesis. These novel findings, for the first time, suggest SLN is the missing link for enhancing SERCA dependent heat generation by uncoupling the pump and this mechanism is recruited to increase energy expenditure during diet overload. However the mechanistic details with regard to recruitment of muscle NST, SLN-mediated uncoupling of SERCA, and how SLN increases muscle metabolism and energetics are poorly understood. The research proposed in this application challenges current thinking that BAT alone is responsible for Nonshivering thermogenesis. It seeks to establish that muscle is an important site of NST and can replace/substitute for thermogenesis in animals where BAT is absent or nonfunctional. The revised proposal places a greater emphasis on understanding the mechanistic basis of muscle NST. The current proposal seeks to identify sub cellular mechanisms that lead to activation of SERCA/SLN based thermogenesis. In Aim 1, we will investigate the mechanism behind activation of muscle-based NST during cold exposure and determine if SLN can replace/substitute for loss of BAT (UCP1) function in mammals. In Aim 2, we will test the therapeutic relevance of SLN and determine if overexpression of SLN can protect against diet- induced obesity by increasing energy expenditure. Another important goal of this aim is to discover how SLN increases muscle metabolism, if this involves Ca2+ dependant signaling pathways. In Aim 3, we will identify the structural features (binding sites and residues) of SLN/SERCA interaction and determine how SLN interaction leads to uncoupling and increased ATP hydrolysis. The experiments proposed here will collectively establish that SLN/SERCA interaction is the mechanism for skeletal muscle based NST and their relevance to Tc and whole body energy metabolism. Most importantly they will provide a mechanistic basis to show that SLN alone but not Phospholamban binding to SERCA causes uncoupling of the SERCA pump. We suggest that a better understanding of muscle thermogenesis has broader implications to our overall understanding of muscle metabolism, energy expenditure and evidently obesity in mammals including humans. Identification of the molecular mechanisms behind muscle based NST is of paramount importance to humans, since this strategy could be exploited to increase energy expenditure in muscle, thereby providing newer targets for obesity treatment.

总结 越来越多的证据表明，除了棕色脂肪组织（BAT），骨骼肌是一个重要的 非颤抖性产热（NST）。尽管一些研究表明SR Ca 2+循环可能 在肌肉产热中发挥作用，分子细节尚不清楚。我们实验室的研究， 其他人已经表明，肌红蛋白（Sarcolipin，SLN），一种SR Ca 2 + ATP酶（SERCA）的调节剂，可以结合到SERCA， Ca 2+的存在促进SERCA解偶联并增加ATP水解。在SLN存在的情况下， SERCA变得低效;每摩尔ATP转运少于2摩尔Ca 2+，从而增加ATP水解 和产热。这些研究提示SLN可能在肌肉产热中发挥作用。 SLN在肌肉中的相关性，我们采取了遗传方法，最近表明，SLN的损失倾向于 小鼠在急性冷暴露期间出现体温过低，但在Sln-/-背景中重新引入SLN完全 恢复了基于肌肉的产热作用此外，当以高脂肪饮食（HFD）喂养时， 体重显著高于WT对照组，而喂食HFD的WT小鼠肥胖程度较低，但显示 SLN的显著上调（3-4倍）表明SLN在饮食诱导的产热中被募集。 这些新的发现，首次表明SLN是增强SERCA的缺失环节 通过解耦泵产生依赖的热量，并且该机制被招募以增加 饮食过量时的能量消耗。然而，关于招募的机械细节， 肌肉NST，SLN介导的SERCA解偶联，以及SLN如何增加肌肉代谢， 能量学知之甚少。 这项申请中提出的研究挑战了目前认为BAT独自负责的想法 无颤抖产热。它试图确定肌肉是NST的重要部位， 在BAT缺失或不起作用的动物中替代/替代产热。的订正提案 更加强调理解肌肉NST的机械基础。目前的提案寻求 鉴定导致基于SERCA/SLN的产热激活的亚细胞机制。目标1： 将研究冷暴露期间基于肌肉的NST激活背后的机制， 确定SLN是否可以替代哺乳动物中BAT（UCP 1）功能的丧失。在目标2中，我们将 测试SLN的治疗相关性，并确定SLN的过表达是否可以防止饮食- 通过增加能量消耗来诱发肥胖。这一目标的另一个重要目标是发现 SLN如何增加肌肉代谢，如果这涉及Ca 2+依赖性信号通路。在目标3中， 我们将确定SLN/SERCA相互作用的结构特征（结合位点和残基）， 确定SLN相互作用如何导致解偶联和增加ATP水解。实验 这里提出的将共同建立SLN/SERCA相互作用是骨骼肌的机制， 基于NST及其与Tc和全身能量代谢的相关性。最重要的是，它将提供一个 机制基础表明，SLN单独而不是Phospholamban与SERCA的结合引起了细胞的解偶联。 SERCA泵。我们认为，更好地了解肌肉产热具有更广泛的意义， 我们对哺乳动物的肌肉代谢、能量消耗和明显肥胖的整体了解 包括人类识别肌肉NST背后的分子机制至关重要 对人类的重要性，因为这种策略可以用来增加肌肉的能量消耗， 从而为肥胖症治疗提供更新的靶点。