IL-15 receptor-alpha and IL-15 action in aging skeletal muscle and adipose tissue

IL-15 受体-α 和 IL-15 在衰老骨骼肌和脂肪组织中的作用

• 批准号: 8139059
• 负责人: LEBRIS S QUINN
• 金额: --
• 依托单位: VA PUGET SOUND HEALTHCARE SYSTEM
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8139059
• 关键词: Adipose tissue; Adult; Affect; Age; Age-Years; Aging; Alzheimer' s Disease; Apoptosis; Apoptotic; Area; Binding; Biochemistry; Biological; Body Composition; Body fat; Caloric Restriction; Cardiovascular Diseases; Cell Culture Techniques; Cell Line; Cells; Chimeric Proteins; Chronic Disease; Complex; Degenerative polyarthritis; Deposition; Diabetes Mellitus; Disease; Drug Design; Economic Burden; Elderly; Electroporation; Epidemic; Exhibits; Fatty acid glycerol esters; Fiber; Fracture; Future; Genes; Genetic Polymorphism; Health; Health Care Costs; Human; Human Biology; In Vitro; Incidence; Infiltration; Insulin Resistance; Interleukin-15; Investigation; Lead; Link; Longevity; Malignant Neoplasms; Mediating; Medical; Medicine; Membrane; Messenger RNA; Molecular; Morbidity - disease rate; Mus; Muscle; Muscle Fibers; Muscle Proteins; Non-Insulin-Dependent Diabetes Mellitus; Obesity; Pathway interactions; Patients; Peptide Signal Sequences; Persons; Plasmids; Population; Prediabetes syndrome; Protein Isoforms; Proteins; Proteolysis; RNA Splicing; Rattus; Research; Retroviral Vector; Risk Factors; Rodent; Role; Sequence Homology; Set protein; Signal Transduction; Single Nucleotide Polymorphism; Skeletal Muscle; Suggestion; System; TNFRSF1A gene; Techniques; Testing; Tissues; Translational Research; Tumor Necrosis Factor-alpha; Variant; Veterans; Visceral; Weight; Work; aging population; cell type; cytokine; design; disability; expression vector; falls; feeding; frailty; functional disability; genetic regulatory protein; human MPP1 protein; human subject; hypertensive heart disease; in vivo; innovation; insulin sensitivity; interleukin-15 receptor; mortality; muscle form; overexpression; patient population; prevent; receptor; response; sarcopenia; skeletal; wasting; young adult

DESCRIPTION (provided by applicant): Aging is characterized by reduced skeletal muscle mass (sarcopenia) and increased visceral adipose tissue deposition. These changes in body composition result in frailty, insulin resistance, and cardiovascular disease, which are major health problems in the aging Veteran population. Interleukin-15 (IL-15) is a muscle-derived cytokine with favorable effects on muscle mass, fat mass, and insulin sensitivity in young mice. Circulating IL-15 levels decline with age, in ad lib-fed, but not calorie- restricted rodents, suggesting declines in IL-15 activity contribute to age-associated changes in body composition. However, while IL-15 has favorable effects on body composition in young mice, IL-15 overexpression in aging mice results in increased fat mass and reduced muscle mass compared to controls. IL-15 secretion and bioactivity are modulated by differential association of IL-15 with several forms of the IL-15 alpha receptor subunit (IL-15R1), which can appear as a membrane-bound form (mbIL-15R1) or as one of two soluble forms (sIL-15R1). The latter can differentially affect IL-15 secretion and activity in a tissue- specific manner. Association of IL-15 with sIL-15R1 variants can also differentially inhibit signaling by tumor necrosis factor-1 (TNF-1), another cytokine involved in muscle wasting and insulin resistance. In human subjects, several single-nucleotide polymorphisms (SNPs) have been described in the IL-15R1 gene which impact muscularity, adiposity, and insulin sensitivity. In skeletal muscle, expression of the alternatively-spliced mRNA variant of IL-15R1 (spliced sIL-15R1) declines with age, suggesting a decrease in IL-15/spliced sIL-15R1 complexes leads to age-associated declines in IL-15 levels and activity. The molecular biochemistry of IL-15 and IL-15R1 interactions are complex, tissue-specific, and have not been well-studied in skeletal muscle or adipose tissue, nor in aging systems. Therefore, this study will test the overall hypothesis that IL-15 has opposing effects on body composition in young and old mice due to decreased expression of spliced sIL-15R1 and increased association of IL-15 with the molecularly distinct, proteolytically-shed sIL-15R1 form. The proposed study will utilize retroviral vectors to overexpress IL-15 and IL-15R1 variants in mouse primary and immortalized skeletal myogenic cultures, in order to define the roles of these molecules in IL-15 secretion and bioactivity in muscle. The effects of IL-15/sIL-15R1 complex variants in mouse immortalized adipogenic cultures will also be determined. The effects of IL-15/sIL-15R1 complex variants on TNFR1- mediated TNF-1 signaling in skeletal myogenic and adipogenic cultures will be determined as well. In vivo, the innovative and translational technique of plasmid electroporation into skeletal muscle (EPM) will be used to induce systemic expression of IL-15, sIL-15R1 variants, and a putative superagonistic IL-15/sIL15R1 fusion protein, in young and normally-aging mice. The effects of these molecules on body composition and insulin sensitivity in response to high-fat feeding, sarcopenia, and TNFR1-mediated skeletal myonuclear apoptosis will be determined. The Specific Aims of the project are: 1. Determine the role of IL-15R1 variants in IL-15 stability, secretion and bioactivity in skeletal myogenic and adipogenic cultures. 2. Determine the role of IL-15R1 variants on IL-15 secretion from muscle, body composition, and insulin sensitivity in vivo. 3. Determine the bioactivity of an IL-15/sIL-15R1 fusion protein in muscle and adipose tissue in young and aging mice. These studies will provide mechanistic information which could be exploited pharmacologically to modulate body composition and the pathological consequences of sarcopenia and adiposity in the elderly. PUBLIC HEALTH RELEVANCE: Aging is characterized by decreases in muscle weight and strength, and increased deposition of fat. These changes lead to frailty and insulin resistance (a kind of pre-diabetes), which are major health problems in aging Veterans. Interleukin-15 (IL-15) is a protein that can prevent muscle wasting, obesity, and insulin resistance in young mice. Also, IL-15 levels are lower in old mice than in young mice. Therefore, IL-15 has been suggested as a therapy for the decreases in muscle and increases in fat in the elderly. This notion is too simplistic, however, because recent findings indicate IL-15 has the opposite effect in aging mice. Another set of proteins regulate IL-15, and the amounts of these regulating proteins change during aging. This project will study the regulatory proteins in mice, to determine whether some help IL-15 and some prevent IL-15 from working, and will study how levels of these substances can be controlled during aging. This information will be used in the future to design drugs which can help prevent muscle wasting, obesity, and insulin resistance in the elderly.

描述（由申请人提供）： 衰老的特征是骨骼肌质量减少（肌肉减少症）和内脏脂肪组织沉积增加。体内组成的这些变化会导致脆弱，胰岛素抵抗和心血管疾病，这是老化退伍军人人口的主要健康问题。 白介素15（IL-15）是一种肌肉衍生的细胞因子，对年轻小鼠的肌肉质量，脂肪质量和胰岛素敏感性有利。循环IL-15水平随着年龄的增长而下降，在Ad Lib喂养的啮齿动物中，但没有限制卡路里的啮齿动物，这表明IL-15活性的下降导致了与年龄相关的身体组成变化。但是，尽管IL-15对年轻小鼠的身体成分具有有利的影响，但与对照组相比，衰老小鼠的IL-15过表达导致脂肪质量增加和肌肉质量降低。 IL-15的分泌和生物活性是通过IL-15与几种形式的IL-15α受体亚基（IL-15R1）的差异关联来调节的，可以以膜结合形式（MBIL-15R1）或一种作为一种或一种两种可溶性形式（SIL-15R1）。后者可以以组织方式差异地影响IL-15的分泌和活性。 IL-15与SIL-15R1变体的缔合还可以差异地抑制肿瘤坏死因子1（TNF-1）的信号传导，这是另一种参与肌肉浪费和胰岛素抵抗的细胞因子。在人类受试者中，在IL-15R1基因中描述了几种单核苷酸多态性（SNP），这些基因影响肌肉，肥胖和胰岛素敏感性。 在骨骼肌中，IL-15R1（剪接的SIL-15R1）的替代切割的mRNA变体的表达随着年龄的增长而下降，表明IL-15/剪接的SIL-15R1复合物的降低导致IL-15水平的年龄相关的IL-15水平下降和活动。 IL-15和IL-15R1相互作用的分子生物化学是复杂的，组织特异性的，并且在骨骼肌或脂肪组织中，也没有在衰老系统中得到很好的研究。因此，这项研究将检验总体假设，即IL-15由于剪接的SIL-15R1的表达降低以及IL-15与分子差异，蛋白水解的SIL-的相关性增加，对年龄和老鼠的身体组成具有相反的影响。 15R1形式。 拟议的研究将利用逆转录病毒载体过表达IL-15和IL-15R1在小鼠原发性和永生化的骨骼肌培养物中的变体，以定义这些分子在IL-15分泌中的作用，并在肌肉中的生物活性中的作用。还将确定IL-15/SIL-15R1复合物在永生的成脂培养物中的影响。还将确定IL-15/SIL-15R1复合变体对骨骼肌源性和脂肪生成培养物TNFR1介导的TNF-1信号传导的影响。在体内，质粒电穿孔到骨骼肌（EPM）的创新和转化技术将用于诱导IL-15，SIL-15R1变体的全身表达，以及推定的超级促进性IL-15/SIL15R1融合蛋白，在年轻人和正常情况下 - 老鼠。这些分子对响应高脂喂养，肌肉减少症和TNFR1介导的骨骼肌核凋亡的影响。该项目的具体目的是：1。确定IL-15R1变体在IL-15稳定性，分泌和生物活性在骨骼肌原性和掺杂性培养中的作用。 2。确定IL-15R1变体对体内肌肉，身体成分和胰岛素敏感性的IL-15分泌的作用。 3。确定年轻小鼠和衰老小鼠中肌肉和脂肪组织中IL-15/SIL-15R1融合蛋白的生物活性。 这些研究将提供机械信息，可以在药理学上利用这些信息来调节身体组成以及肌肉减少症和老年人肥胖的病理后果。 公共卫生相关性： 衰老的特征是肌肉体重和力量的降低以及脂肪沉积的增加。这些变化导致脆弱和胰岛素抵抗（一种糖尿病前），这是老化退伍军人的主要健康问题。白介素-15（IL-15）是一种蛋白质，可以防止幼鼠的肌肉浪费，肥胖和胰岛素抵抗。同样，老鼠的IL-15水平低于年轻小鼠。因此，已提出IL-15作为肌肉降低和老年人脂肪增加的一种疗法。但是，这个概念太简单了，因为最近的发现表明IL-15在老化小鼠中具有相反的作用。另一组蛋白质调节IL-15，这些调节蛋白质的量在衰老过程中发生变化。该项目将研究小鼠中的调节蛋白，以确定有些人是否有助于IL-15和有些防止IL-15起作用，并将研究如何在衰老期间控制这些物质水平。将来将使用此信息来设计有助于防止肌肉浪费，肥胖和胰岛素抵抗的药物。