Modulation of Contraction-Induced Changes in Muscle mTOR Signaling by Alcohol

描述（由申请人提供）：酗酒和慢性酒精滥用（即酒精中毒）是重要的公共卫生问题，因为这些问题与高危行为、多器官系统功能障碍、疾病恢复受损甚至过早死亡有关。习惯性酒精滥用导致骨骼肌肌病，其特征在于肌肉损失、虚弱和身体功能下降。这些症状与分子变化相关，包括骨骼肌中mTOR依赖性蛋白质合成速率降低。很少有治疗策略存在，以帮助从这种疾病的恢复，无论是在持续存在的酒精和情况下，戒酒是实现。然而，骨骼肌收缩激活mTOR激酶活性并增加蛋白质合成。重要的是，当间歇性收缩刺激持续数周时，它会诱导显著的肌肉生长和肌肉功能的协调增加。因此，受刺激的肌肉收缩，无论是自愿或通过经皮电刺激，可能是一个潜在的治疗方式与酒精性肌肉疾病的个人谁有有限的流动性和功能能力。我们的长期目标是确定酒精对骨骼肌蛋白质合成和mTOR活性的影响，这些活性已通过刺激肌肉收缩而增加，并确定潜在的信号变化和介导观察到的反应的新蛋白质。（1）确定急性酒精中毒是否逆转由急性或慢性肌肉收缩诱导的mTOR活性、蛋白质合成和肌肉肥大的预先存在的增加;（2）建立慢性酒精性肌病模型中急性和慢性肌肉收缩与肌肉mTOR活性变化的治疗相关性，（3）确定急性和慢性酒精后TSC 2和mTOR的内体/溶酶体靶向作用，以及与先前观察到的肥大、收缩性和mTOR信号传导的变化相关的肌肉收缩;和（4）使用嘌呤霉素相关新生链蛋白质组学鉴定其合成速率被酒精和/或肌肉收缩改变的骨骼肌蛋白质（PUNCH- P）。这些目标代表了一组新颖而全面的实验，利用几种创新的体内和体外技术，包括急性和慢性酒精滥用的啮齿动物模型，分离的肌肉力量和疲劳性测试，mTOR和TSC 2分子运输的可视化，以及质谱法来识别酒精和肌肉收缩后新产生的蛋白质。从这些实验中获得的数据将提供临床相关知识，以显着推进治疗策略，并有助于对急性和慢性酒精性肌肉疾病的病因学的机械理解。

DESCRIPTION (provided by applicant): Binge drinking and chronic alcohol abuse (i.e. alcoholism) represent important public health issues as these are associated with high risk behaviors, multiple organ system dysfunction, impaired recovery from illness and even premature death. Habitual alcohol abuse leads to skeletal muscle myopathy characterized by muscle loss, weakness, and decreased physical function. These symptoms are associated with molecular changes including a depressed rate of mTOR-dependent protein synthesis in skeletal muscle. Few treatment strategies exist to aid in the recovery from this disease both in the continued presence of alcohol and under circumstances where abstinence is achieved. However, skeletal muscle contraction activates mTOR kinase activity and increases protein synthesis. Importantly, when an intermittent contractile stimulus is sustained over several weeks it induces significant muscle growth and a coordinate increase in muscle function. Therefore, stimulated muscle contraction, either voluntarily or via transcutaneous electrical stimulation, may represent a potential therapeutic modality for individuals with alcoholic muscle disease who have limited mobility and functional capacity. Our long term goal is to determine the effects of alcohol on skeletal muscle protein synthesis and mTOR activity that has been increased by stimulated muscle contraction, and to identify potential signaling changes and new proteins that mediate the observed response. Progression towards this goal will be achieved through the following specific aims: (1) Determine whether acute alcohol intoxication reverses the pre-existing increase in mTOR activity, protein synthesis and muscle hypertrophy induced by acute or chronic muscle contraction; (2) Establish the therapeutic relevance of acute and chronic muscle contraction in a model of chronic alcoholic myopathy with regards to changes in muscle mTOR activity, protein synthesis and muscle hypertrophy; (3) Define the role of endosomal/lysosomal targeting of TSC2 and mTOR following acute and chronic alcohol, and muscle contraction relevant to previously observed changes in hypertrophy, contractility and mTOR signaling; and (4) Identify skeletal muscle proteins whose synthetic rate is altered by alcohol and/or muscle contraction using puromycin-associated nascent chain proteomics (PUNCH- P). These aims represent a set of novel and comprehensive experiments utilizing several innovative in vivo and ex vivo techniques including rodent models of acute and chronic alcohol abuse, isolated muscle strength and fatigability testing, visualization of the molecular trafficking of mTOR and TSC2, as well as mass spectrometry to identify newly made proteins following alcohol and muscle contraction. Data garnered from these experiments will provide clinically relevant knowledge to significantly advance treatment strategies and contribute to the mechanistic understanding of the etiology of acute and chronic alcoholic muscle disease.