Physiology of Respiratory Muscle Cells

说明(申请人提供)：肿瘤坏死因子-α(TNF-α)是 建议促进呼吸和四肢骨骼的萎缩和虚弱 从慢性阻塞性肺病到各种疾病的肌肉 癌症，从充血性心力衰竭到艾滋病。尽管它推定 病理生理学意义，令人惊讶的是，对 肿瘤坏死因子-α在骨骼肌中的作用机制。这样做的长期目标是 项目是确定肿瘤坏死因子-α妥协的氧化还原机制 肌肉表现。到目前为止，我们已经确定了与临床相关的 肿瘤坏死因子-α水平直接作用于骨骼肌细胞，刺激骨骼肌细胞丢失 肌肉蛋白质，不会导致细胞凋亡或坏死。早些时候 这种分解代谢反应中的信号事件包括核的激活 因子-kB(NFkB)。在几天内，肿瘤坏死因子-α/NFkB信号加速 肌肉蛋白质的降解，造成蛋白质的净损失。当前项目 扩展了我们在这一途径上的工作，以解决潜在的信号事件 更深入的研究和评估加速蛋白质降解的机制。 我们有三个具体目标：1.定义受体介导的信号事件 通过肿瘤坏死因子-α激活骨骼肌中的NFkB。2.)评估 肿瘤坏死因子-α对泛素结合活性的调节。3.)要评估 泛素结合酶UbcH2作为一种重要的细胞因子 TNF-α/NFkB调节的分解代谢。这些目标将通过一个 整合肌肉制剂的综合方法，范围包括 将肌管培养成经肿瘤坏死因子-α处理的动物。因果关系将 使用一组药理学、免疫学和遗传学方法进行评估 干预措施。拟议的研究结果将有助于建立分子 肿瘤坏死因子α刺激呼吸和肢体分解代谢的机制 骨骼肌。

DESCRIPTION (provided by applicant): Tumor necrosis factor-alpha (TNF-alpha) is suggested to promote atrophy and weakness of respiratory and limb skeletal muscles in diseases that range from chronic obstructive pulmonary disease to cancer, from congestive heart failure to AIDS. Despite its putative pathophysiological significance, surprisingly little is known about the mechanisms of TNF-alpha action in skeletal muscle. The long-term goal of this project is to determine the redox mechanisms by which TNF-alpha compromises muscle performance. Thus far, we have established that clinically-relevant levels of TNF-alpha act directly on skeletal muscle cells to stimulate loss of muscle protein without inducing apoptotic or necrotic cell death. Early signaling events in this catabolic response include activation of nuclear factor-kB (NFkB). Over several days, TNF-alpha/NFkB signaling accelerates degradation of muscle protein, causing a net protein loss. The current project extends our work on this pathway to address the underlying signaling events in greater depth and to evaluate the mechanism of accelerated protein degradation. We have three Specific Aims: 1.) To define receptor-mediated signaling events by which TNF-alpha activates NFkB in skeletal muscle. 2.) To evaluate regulation of ubiquitin conjugating activity by TNF-alpha. 3.) To evaluate the ubiquitin conjugating enzyme UbcH2 as an essential element of TNF-alpha/NFkB-regulated catabolism. These aims will be addressed using an integrative approach that incorporates muscle preparations ranging from cultured myotubes to TNF-alpha treated animals. Cause/effect relationships will be evaluated using a panel of pharmacologic, immunologic, and genetic interventions. Results of the proposed studies will help establish molecular mechanisms whereby TNFalpha stimulates catabolism of respiratory and limb skeletal muscle.