A novel role for oxidized lipid mediators as effectors of muscle atrophy and weakness in aging

氧化脂质介质作为衰老过程中肌肉萎缩和无力效应物的新作用

• 批准号: 10710399
• 负责人: HOLLY VAN REMMEN
• 金额: $ 56.33万
• 依托单位: OKLAHOMA MEDICAL RESEARCH FOUNDATION
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-09-30 至 2027-05-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10710399
• 关键词: Affect; Age; Aging; Arachidonate 15-Lipoxygenase; Arachidonic Acids; Atrophic; Autophagocytosis; Cell Death; Cells; Data; Degradation Pathway; Denervation; Development; Diameter; Drug Metabolic Detoxication; Effectiveness; Elderly; Enzymes; Generations; Goals; In Vitro; Individual; Intervention; Knockout Mice; Link; Lipid Peroxides; Measures; Mediating; Mediator; Membrane; Mitochondria; Modeling; Mus; Muscle; Muscle Cells; Muscle Fibers; Muscle Mitochondria; Muscle Weakness; Muscle function; Muscular Atrophy; Pathway interactions; Pattern; Phospholipase A2; Phospholipids; Population; Production; Public Health; Publishing; Quality of life; Risk; Role; Testing; Wild Type Mouse; Work; age related; age-related muscle loss; design; effective intervention; experimental study; falls; frailty; healthspan; improved; in vivo; inhibitor; insight; intervention effect; lipid mediator; muscle form; muscle metabolism; nerve supply; novel; oxidation; oxidative damage; oxidized lipid; pharmacologic; prevent; protective effect; protein degradation; proteostasis; response; sarcopenia; successful intervention; therapeutic target

Abstract. Sarcopenia, the loss of muscle mass and function with age, is a universal problem in the growing elderly population. To design effective interventions we need to better understand the mechanism(s) responsible for initiation and progression of muscle atrophy and weakness in aging. Studies from our lab and others have shown that loss of innervation is a key driver of muscle atrophy with age. The goal of this proposal is to test a novel hypothesis that bioactive lipid mediators (oxylipins and oxidized phospholipids (oxPL)), are primary effectors for muscle atrophy and weakness. Our hypothesis is strongly supported by our data showing that denervation induces activation of phospholipase A2 (cPLA2), releasing arachidonic acid (AA) from muscle membranes that can promote generation of oxidized lipids, either non-enzymatically or via 12/15 lipoxygenase (Alox15) dependent generation. We have also shown that denervation-induced muscle loss is decreased when AA release and oxidized lipids are blocked by inhibition of cPLA2 or Alox15, or by scavenging of LOOH using liproxstatin-1 or Gpx4Tg mice, thus supporting oxPL/oxylipins as a critical mechanistic link between denervation and muscle wasting. However, the mechanisms by which oxPL/oxylipins cause muscle atrophy have not been defined. Based on previously identified targets of these lipid mediators, we are specifically testing the hypothesis that oxPL/oxylipins induced by denervation cause damage to membranes, promote mitochondrial changes and activate proteolytic and cell death pathways to induce age-related muscle atrophy. In Aim 1, we will define the effect of modulating oxylipins on atrophy related targets by inhibiting generation of oxPL/oxylipins (using cPLA2KO and Alox15KO mice) and by altering reduction of lipid hydroperoxides (using Gpx4/Tg and muscle specific Gpx4KO mice and treatment with liproxstatin-1) on membrane oxidative damage, mitochondrial function, muscle degradative and cell death pathways and muscle mass after denervation. These experiments will identify the primary oxylipins produced in denervated muscle and identify the critical targets of oxylipins that lead to muscle atrophy and weakness. In Aim 2, we will measure the effect of key oxylipins identified in Aim 1 in vitro in C2C12 muscle cells on oxidative damage, mitochondrial function, protein degradation pathways and muscle fiber diameter. These experiments will provide new information on the effect of specific oxylipins on muscle metabolism and mitochondrial function. Finally, in Aim 3, we will test whether inhibiting oxylipin generation in vivo in muscle specific Alox15KO mice or reducing levels of lipid hydroperoxides (LOOH) in mice with elevated levels of Gpx4 expression can protect against age-related muscle atrophy in vivo in aging mice. We predict that reduced generation of oxPL/oxylipins and enhanced detoxification of lipid hydroperoxides (LOOH) will modify the atrophy targets outlined in Aim 1, reducing muscle atrophy and weakness in aging mice. Overall, these experiments will be the first to investigate the role of oxylipins in sarcopenia and their potential as a target for intervention in muscle loss and weakness.

抽象的。肌肉减少症是肌肉质量和随着年龄的功能的损失，是增长的普遍问题 老年人。为了设计有效的干预措施，我们需要更好地了解负责的机制 用于肌肉萎缩和衰老无力的启动和进展。我们实验室和其他人的研究有 表明神经损失是随着年龄的增长的肌肉萎缩的关键驱动力。该建议的目的是测试 一种新的假设，即生物活性脂质介质（Oxylipins和氧化磷脂（OXPL））是 肌肉萎缩和无力的主要效应子。我们的数据强烈支持我们的假设 表明去神经诱导磷脂酶A2（CPLA2）的激活，从 肌肉膜可以促进非酶或通过12/15的氧化脂质的产生 脂氧合酶（ALOX15）依赖性产生。我们还表明，神经支配引起的肌肉损失是 当AA释放和氧化脂质被抑制CPLA2或ALOX15或通过清除时，减少了 使用liproxstatin-1或gpx4TG小鼠的LooH，因此支持OXPL/Oxylipins作为关键机械链接 在神经支配和肌肉浪费之间。但是，oxpl/oxylipin引起肌肉的机制 萎缩尚未定义。基于这些脂质介质的先前确定的目标，我们具体是 测试以神经保护诱导的oxpl/oxylipin对膜损害的假设， 促进线粒体变化并激活蛋白水解和细胞死亡途径以诱导年龄相关 肌肉萎缩。在AIM 1中，我们将通过抑制萎缩对萎缩相关靶靶标的作用 OXPL/Oxylipins（使用CPLA2KO和Alox15KO小鼠）的产生，并通过改变脂质的还原 在 膜氧化损伤，线粒体功能，肌肉降解和细胞死亡途径和肌肉 肿块后的神经支配。这些实验将鉴定在不死的肌肉中产生的原代阿氧蛋白 并确定催产素的关键靶标，这些靶标会导致肌肉萎缩和无力。在AIM 2中，我们将衡量 C2C12肌肉细胞中AIM 1中鉴定在AIM 1中鉴定的关键氧蛋白对氧化损伤，线粒体的影响 功能，蛋白质降解途径和肌肉纤维直径。这些实验将提供新的 有关特异性氧蛋白对肌肉代谢和线粒体功能的影响的信息。最后，目标 3，我们将测试抑制肌肉特异性ALOX15KO小鼠体内抑制阿氧蛋白的产生还是降低水平 GPX4表达水平升高的小鼠中的脂质氢过氧化物（LOOH）可以预防与年龄有关 衰老小鼠体内肌肉萎缩。我们预测，OXPL/Oxylipins的产生和增强 脂质氢过氧化物（LOOH）的排毒将改变AIM 1中概述的萎缩靶标，从而减少肌肉 衰老小鼠的萎缩和弱点。总体而言，这些实验将是第一个研究氧基蛋白的作用的实验 在肌肉减少症及其作为干预肌肉丧失和无力的目标的潜力。