Muscle Gene Expression Following Denervation and Disuse

描述（由申请人提供）：本研究的主要目的是阐明在失神经支配和废用后肌肉中过量蛋白质分解的机制，并确定这些机制是否不同于由全体性疾病引起的肌肉萎缩。这将是重要的阐明是否有特定的影响，由于损失的营养刺激的神经，除了所看到的影响。为了更全面地了解去神经支配后基因表达的变化，将进行基因芯片分析，以跟踪导致蛋白质水解增强和肌肉功能丧失的mRNA的全局变化。然后将这些变化与脊髓隔离（一种完全废弃的实验模型）所见的变化进行比较。此外，已经确定的对蛋白质水解很重要的特定基因的表达（例如新发现的泛素连接酶，atrogin-1）将作为神经切片和废弃后时间的函数进行比较。体外肌肉细胞培养将用于研究触发肌肉肥大的信号通路的激活如何参与抑制蛋白质降解。通过使用这些通路的生长因子和抑制剂，并监测新发现的泛素连接酶和其他萎缩基因的表达，本研究将试图确定是否存在调节肥大和萎缩的共同机制。这些实验应该有助于更好地理解在萎缩中起关键作用的信号，以及它们在不同的萎缩状态下是如何被调节的。这项研究也可能有助于确定新的治疗靶点和方法来延缓这些病理状态下的肌肉萎缩。

DESCRIPTION (provided by applicant): The primary goal of this research is to clarify the mechanisms responsible for the excessive protein breakdown in muscle following denervation and disuse and to determine whether these mechanisms differ from those of muscle atrophy resulting from systemic diseases. It will be important to elucidate whether there are specific effects due to loss of the trophic stimulus from the nerve, in addition to the effects seen with disuse. To gain a more complete understanding of the changes in gene expression following denervation, gene-chip analysis will be undertaken in order to follow global changes in mRNA leading to enhanced proteolysis and loss of muscle function. These changes will then be compared with those seen with spinal isolation, an experimental model of complete disuse. Furthermore, the expression of specific genes that have already been identified as important to proteolysis (e.g. the newly identified ubiquitin ligase, atrogin-1) will be compared as a function of time after nerve section and disuse. In vitro muscle cell cultures will then be used to examine how activation of signaling pathways that trigger muscle hypertrophy may be involved in suppressing protein degradation. By using growth factors and inhibitors of these pathways and monitoring the expression of the newly identified ubiquitin ligases and other atrophy genes, this research will attempt to identify whether there are common mechanisms regulating hypertrophy and atrophy. These experiments should aid in better understanding of the signals that play a key role in atrophy and how they are regulated following different atrophy states. This research may also help to identify new therapeutic targets and ways to retard muscle wasting in these pathological states.