Cytokine Regulation of Muscle Protein Synthesis During Infection

感染过程中肌肉蛋白合成的细胞因子调节

基本信息

批准号：
7921710
负责人：
CHARLES H. LANG
金额：
$ 16.66万
依托单位：
PENNSYLVANIA STATE UNIV HERSHEY MED CTR
依托单位国家：
美国
项目类别：
财政年份：
2009
资助国家：
美国
起止时间：
2009-09-15 至 2011-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7921710
关键词：
Address Affect Anabolic Agents Atrophic Binding Branched-Chain Amino Acids Burn Trauma Clinical Complex Data Defect Development Equilibrium Genetic Translation Goals Impairment In Vitro Incubated Infection Inflammation Mediators Inflammatory Injury Knockout Mice Lead Leucine Link Lipids Mediating Methods MicroRNAs Molecular Molecular Genetics Morbidity - disease rate Mus Muscle Muscle Cells Muscle Fibers Muscle Proteins Muscular Atrophy Myopathy NOS2A gene Nitric Oxide Nutrient Outcome Patients Phosphorylation Phosphotransferases Physiological Positioning Attribute Principal Investigator Production Productivity Protein Biosynthesis Protein Isoforms Proteins Raptors Rattus Recovery Regulation Rehabilitation therapy Relative (related person)Research Resistance Role Scaffolding Protein Sepsis Signal Transduction Skeletal Muscle System TNFRSF1A gene Testing Translation Initiation Translations Trauma Tumor Necrosis Factor-alpha Tumor Necrosis Factors Up-Regulation Wild Type Mouse Work autocrine cytokine experience helicase improved in vivo insight mTOR protein mortality novel novel therapeutics nutrition paracrine public health relevance response scaffold septic small hairpin RNA therapy design wasting

项目摘要

DESCRIPTION (provided by applicant): Muscle wasting remains a cause of morbidity and mortality after trauma, burns and infection. Although the mechanisms for the atrophic response are multifactorial and poorly defined, our work documents the causal relationship between the up regulation of inflammatory modulators, particularly TNF" and NO, and the decreased translational control of muscle protein synthesis. The sepsis-induced defect is manifested not only under basal conditions but also as a reduced responsiveness to leucine which acts as an anabolic nutrient signal. Our data suggest these sepsis-induced changes are mediated by inhibition of mTOR kinase signaling in skeletal muscle. Our long-term goal is to elucidate the cellular and molecular mechanisms by which sepsis impairs muscle protein balance leading to the development of muscle atrophy. To address the questions implicit in this goal our proposed research has the following specific aims: (1) Elucidate the mechanism by which sepsis impairs mTOR kinase activity and cap-dependent translation initiation in muscle under basal conditions and in response to leucine by determining whether sepsis alters the interaction of 4E-BP1 and S6K1 with the scaffold protein raptor, the binding activity of the eIF3 scaffolding complex, and/or the binding of PDCD4 to eIF4A and thereby altering helicase activity. (2) Delineate the mechanism by which sepsis impairs the topology of protein synthesis by altering the intracellular localization of components of the translational apparatus. Specifically, we will assess the role of Vps34, a nutrient-regulated lipid kinase, and Rab5 in regulating intracellular mTOR localization. (3) Determine whether sepsis decreases mTOR kinase activity by altering the phosphorylation and/or binding of the Akt substrate PRAS40. (4) Determine the mechanism by which sepsis-induced changes in microRNAs, particularly miR133, decrease global translation initiation. (5) Elucidate the relative contribution of systemic versus locally produced TNF" and NO in disrupting mTOR signaling in muscle. This final aim directly addresses the importance of autocrine/paracrine production of inflammatory mediators in sepsis-induced muscle wasting by using primary cultures of myocytes isolated from TNFR1 null mice or in complementary in vivo studies where shRNA specific for TNF" is electroporated locally into muscle. Collectively, these studies are unique as they integrate in vitro and in vivo approaches permitting detailed effector mechanisms to be defined and the physiological relevance of the observations to be confirmed. These studies will provide new insights into this critical regulatory system and the integrative control mechanisms exerted by a key nutrient signal. They will lead not only to a thorough understanding of sepsis- induced myopathy but also of other health-related conditions characterized by muscle wasting and nutrient resistance. The proposed studies have a translational underpinning in that they will stimulate the development of novel clinical interventions designed to abrogate the long-term consequences of sepsis- and trauma-induced myopathy which impedes recovery and rehabilitation. PUBLIC HEALTH RELEVANCE: The loss of muscle in patients after infection or traumatic injury delays recovery and may decrease survival. The reason why this wasting occurs is not fully understood, but it cannot be fully corrected by providing adequate nutrition. Our research will determine the mechanism for this muscle atrophy which will ultimately lead to development of novel therapeutic treatment and improve patient outcome.

描述（由申请人提供）：肌肉浪费仍然是创伤，烧伤和感染后发病率和死亡率的原因。 Although the mechanisms for the atrophic response are multifactorial and poorly defined, our work documents the causal relationship between the up regulation of inflammatory modulators, particularly TNF" and NO, and the decreased translational control of muscle protein synthesis. The sepsis-induced defect is manifested not only under basal conditions but also as a reduced responsiveness to leucine which acts as an anabolic nutrient signal. Our data suggest these败血症诱导的变化是通过抑制MTOR激酶信号在骨骼肌中的介导的，我们的长期目标是阐明脓毒症的细胞和分子机制，从而损害了肌肉蛋白质平衡，从而损害了肌肉的发展，从而在此目标中脱颖而出。肌肉在基础条件下的cap依赖性翻译起始，并通过确定败血症改变4e-bp1和S6K1与脚手架蛋白猛禽的相互作用是EIF3支架复合物的结合活性和/或PDCD4与EIF4A与EIF4A的结合和此相结合。（2）描述败血症通过改变翻译设备组件的细胞内定位来损害蛋白质合成的拓扑的机制。具体而言，我们将评估VPS34，营养素调节的脂质激酶和RAB5在调节细胞内MTOR定位中的作用。（3）确定败血症是否通过改变AKT底物PRAS40的磷酸化和/或结合来降低mTOR激酶活性。（4）确定败血症诱导的microRNA变化（尤其是miR133）的机制减少了全局翻译起始。 (5) Elucidate the relative contribution of systemic versus locally produced TNF" and NO in disrupting mTOR signaling in muscle. This final aim directly addresses the importance of autocrine/paracrine production of inflammatory mediators in sepsis-induced muscle wasting by using primary cultures of myocytes isolated from TNFR1 null mice or in complementary in vivo studies where shRNA specific for TNF" is将局部电穿孔成肌肉。总的来说，这些研究是独一无二的，因为它们在体外和体内方法整合，允许定义详细的效应机制以及要确认观察结果的生理相关性。这些研究将为这个关键的调节系统以及由关键营养信号施加的整合控制机制提供新的见解。它们不仅会彻底了解败血症引起的肌病，而且对其他与健康相关的疾病的理解，其特征是肌肉浪费和营养耐药性。拟议的研究具有转化的基础，因为它们将刺激旨在消除败血症和创伤引起的肌病的长期后果的新型临床干预措施的发展，从而阻碍了恢复和康复。公共卫生相关性：感染或创伤性损伤后患者肌肉的丧失会延迟康复，并可能降低生存率。发生这种浪费的原因尚未完全理解，但是不能通过提供足够的营养来完全纠正。我们的研究将确定这种肌肉萎缩的机制，这最终将导致新的治疗治疗的发展并改善患者结局。