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

基本信息

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
项目类别：
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

项目摘要

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（由申请人提供）：越来越多的证据表明，除了棕色脂肪组织（BAT）之外，骨骼肌也是非颤抖产热（NST）的重要部位。尽管一些研究表明 SR Ca2+ 循环可能在肌肉生热作用中发挥作用，但分子细节尚不清楚。我们实验室和其他实验室的研究表明，肌磷脂 (SLN) 是 SR Ca2+ ATP 酶 (SERCA) 的调节剂，在 Ca2+ 存在的情况下可以与 SERCA 结合，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 运输少于 2 摩尔 Ca2+，从而增加 ATP 水解和产热。这些研究暗示 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，我们采用了遗传学方法，最近表明，SLN 的丧失会使小鼠在急性寒冷暴露期间容易出现体温过低，但在 Sln 中重新引入 SLN -/- 背景完全恢复基于肌肉的生热作用。此外，当喂食高脂肪饮食（HFD）的 Sln-/- 小鼠比 WT 对照组体重增加显着更多时，喂食 HFD 的 WT 小鼠肥胖程度较低，但显示 SLN 显着上调（3-4 倍），这表明 SLN在饮食诱导的生热作用中被招募。这些新发现首次表明，SLN 是通过解耦泵来增强 SERCA 依赖性热量产生的缺失环节，并且该机制被用来增加饮食超负荷期间的能量消耗。然而，关于肌肉 NST 募集、SLN 介导的 SERCA 解偶联以及 SLN 如何增加肌肉代谢和能量的机制细节知之甚少。本申请中提出的研究挑战了当前认为 BAT 单独负责不颤抖产热的观点。它试图确定肌肉是 NST 的重要部位，并且可以替代/替代 BAT 缺失或无功能的动物的生热作用。修订后的提案更加强调理解肌肉 NST 的机制基础。目前的提案旨在确定导致基于 SERCA/SLN 生热作用激活的亚细胞机制。在目标 1 中，我们将研究寒冷暴露期间基于肌肉的 NST 激活背后的机制，并确定 SLN 是否可以替代/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发的肥胖。该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 Ca2+ 依赖性信号通路）。在目标 3 中，我们将鉴定 SLN/SERCA 相互作用的结构特征（结合位点和残基），并确定 SLN 相互作用如何导致解偶联和增加 ATP 水解。这里提出的实验将共同确定 SLN/SERCA 相互作用是基于骨骼肌的 NST 的机制及其与 Tc 和全身能量代谢的相关性。最重要的是，他们将提供一个机制基础来表明，单独的 SLN 而不是 Phospholamban 与 SERCA 的结合会导致 SERCA 泵的解偶联。我们认为，更好地理解肌肉生热作用对于我们对包括人类在内的哺乳动物的肌肉代谢、能量消耗和明显肥胖的整体理解具有更广泛的影响。识别基于肌肉的 NST 背后的分子机制对人类至关重要，因为可以利用这种策略来增加肌肉的能量消耗，从而为肥胖治疗提供新的目标。