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

基于健康和疾病中非颤抖产热的骨骼肌募集

• 批准号: 9135404
• 负责人: Muthu Periasamy
• 金额: $ 42.41万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 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/9135404
• 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; Disease; Elements; Energy Metabolism; Fatty Acids; Generations; Goals; Health; Heating; High Fat Diet; 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; genetic approach; metabolic rate; muscle metabolism; mutant; natural hypothermia; novel; obesity treatment; overexpression; phospholamban; protein protein interaction; research study; sarcolipin

DESCRIPTION (provided by applicant): Increasing evidence suggests 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.

描述(申请人提供)：越来越多的证据表明，除了棕色脂肪组织(BAT)，骨骼肌是非颤抖产热(NST)的重要部位。虽然一些研究表明，肌质网钙循环可能在肌肉产热中发挥作用，但分子细节尚不清楚。本实验室等人的研究表明，肌浆网钙离子ATPase(SERCA)的调节剂Sarcolipin(SLN)可以在有钙离子存在的情况下与SERCA结合，促进SERCA的解偶联，增加ATP的水解率。在SLN存在的情况下，SERCA变得效率低下；每摩尔ATP转运的钙离子不到2摩尔，从而增加了ATP的水解和产热。这些研究提示SLN可能在肌肉产热中发挥作用。为了确定SLN在肌肉中的相关性，我们采取了遗传学的方法，最近发现SLN的丢失使小鼠在急性冷暴露时容易出现体温低下，但在SLN中重新引入SLN-/-背景完全恢复了肌肉的产热。此外，当SLN-/-小鼠喂食高脂饮食(HFD)时，体重显著高于WT对照组，而喂高脂饮食的WT小鼠体重较轻，但SLN显著上调(3-4倍)，这表明SLN被招募到饮食诱导的产热中。这些新的发现首次表明，SLN是通过解偶联泵来增强SERCA依赖的热量产生的缺失环节，这一机制被用来在饮食超负荷期间增加能量消耗。然而，关于肌肉NST的募集、SLN介导的SERCA解偶联以及SLN如何促进肌肉代谢和能量学的机制细节还知之甚少。这项申请中提出的研究挑战了目前认为蝙蝠单独负责非颤抖生热的想法。它试图确定肌肉是NST的重要部位，可以替代/替代蝙蝠缺失或不起作用的动物的产热作用。修订后的提案更加强调了解肌肉NST的机制基础。目前的提议试图确定导致基于SERCA/SLN的产热激活的亚细胞机制。在目标1中，我们将研究冷暴露时肌肉NST激活的机制，并确定SLN是否可以取代/替代哺乳动物中BAT(UCP1)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的过度表达是否可以通过增加能量消耗来预防饮食诱导的肥胖。这一目标的另一个重要目标是发现SLN如何促进肌肉代谢，如果这涉及到钙依赖的信号通路。在目标3中，我们将确定SLN/SERCA相互作用的结构特征(结合部位和残基)，并确定SLN相互作用如何导致解偶联和增加ATP水解率。这些实验将共同确立SLN/SERCA相互作用是基于骨骼肌的NST的机制，以及它们与TC和全身能量代谢的关系。最重要的是，它们将提供一个机制基础来证明SLN本身而不是与SERCA结合的磷蛋白导致SERCA泵的解偶联。我们认为，更好地理解肌肉产热机制对我们全面了解肌肉新陈代谢、能量消耗以及包括人类在内的哺乳动物的明显肥胖具有更广泛的意义。识别基于肌肉的NST背后的分子机制对人类至关重要，因为这一策略可以被利用来增加肌肉的能量消耗，从而为肥胖治疗提供新的靶点。