Muscle Gene Expression Following Denervation and Disuse

描述(申请人提供)：这项研究的主要目标是阐明去神经和停用后肌肉中蛋白质过度分解的机制，并确定这些机制是否与系统性疾病导致的肌肉萎缩不同。重要的是要阐明，除了停用所见的影响外，是否由于失去神经的营养刺激而产生特定的影响。为了更全面地了解失神经后基因表达的变化，将进行基因芯片分析，以跟踪导致蛋白分解增强和肌肉功能丧失的mRNA的全球变化。然后将这些变化与脊柱隔离的结果进行比较，脊柱隔离是一种完全停用的实验模型。此外，已经被确定为对蛋白质分解重要的特定基因(例如，新发现的泛素连接酶，阿托金-1)的表达将在神经切断和停用后作为时间的函数进行比较。在体外，肌肉细胞培养将被用来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的降解。通过使用这些途径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共同的机制来调节肥大和萎缩。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，以及它们在不同萎缩状态下是如何调节的。这项研究还可能有助于确定新的治疗目标和方法，以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.