GENE EXPRESSION IN OLD AND/OR DENERVATED MUSCLE

这个项目旨在验证我们的假设，即EF的姊妹基因S1- 1α，作为一个候选的“维持基因”来维持 成熟肌管的长寿命和终末分化状态 肌肉。在肌肉发育过程中，S1的表达被激活 伴随而来的是EF-1α蛋白水平的下降，但不是消息水平， 提示转录后抑制EF-1的调节。 1α丰度，并导致EF-1α比率从高 太低了。低EF-1α/S1比率在成人肌肉中持续存在，但在 马卡因引起的损伤、长期失神经、或 年事已高。我们还发现，稳定地将S1转染到S1- 阴性小鼠成纤维细胞诱导内源性EF-2的抑制 1阿尔法。计划中的实验是为了测试我们的工作假设 在肌管中，S1可能起“调光开关”的作用，抑制EF- 1α活性，通过翻译降低其蛋白质丰度 抑制和/或蛋白质快速周转。这一抑制行动 可能会使EF-1α不仅在其传统功能上受到抑制 蛋白质翻译，也有其他已知的功能，如参与 在信号转导中，切断微管或捆绑肌动蛋白 长丝，所有这些都可能导致建立均匀的齿轮范围 有利于成熟肌肉的长期非凋亡状态。这个 制定的具体目标是：1.测试转录后基因 抑制成人肌肉中EF-1α蛋白水平 发育依赖和S1基因表达；2.确定 EF-2转录后抑制的调控模式 1α蛋白水平；3.研究S1基因的表达情况 与EF-1α蛋白丰度的抑制有关，以及与 确定应负责任的顺式因素(S)和反式因素(S)； 在培养中检验肌肉纤维萎缩是由于 卫星细胞的肌管凋亡与复制性衰老 人口；5.检验假设从低到高的变化 EF-1α/S1比值参与细胞死亡的激活 肌管；6.研究调控机制(S) 调控EF-1α/S1比值由低向高的变化 损伤、长期神经丧失和衰老。机制研究(S) 调节EF-1α/S1比率最终将允许设计 控制或减缓肌肉退化的分子操作， 这是一种困扰大多数老年人的疾病。

This project aims to test our hypothesis that S1, a sister gene of EF- 1alpha, functions as a candidate "maintenance gene" to maintain the long-lived and terminally differentiated state for myotubes in mature muscle. During development in muscle, S1 expression is activated with a concomitant decline in EF-1alpha protein, but not message, level, suggesting a posttranscriptional suppression of the regulation of EF- 1alpha abundance, and resulting a shift in EF-1alpha ratio from high to low. The low EF-1alpha/S1 ratio persists in adult muscle except in the cases of marcaine-induced injury, long-term denervation, or extreme old age. We also found that stable transfection of S1 into S1- negative mouse fibroblasts induces suppression of endogenous EF- 1alpha. Experiments planned are to test our working hypothesis that in myotubes, S1 may function as a "dimmer switch", dampening EF- 1alpha activity by reducing its protein abundance via translational suppression and/or rapid protein turnover. This dampening action may leave EF-1alpha restrained in not only its traditional function in protein translation, but also other known functions such as involvement in signal transduction, severing microtubles, or bundling actin filaments, all of which may result in establishing an even gear range favorable to the long-term nonapoptotic state in mature muscle. The specific aims formulated are: 1. To test whether posttranscriptional suppression of EF-1alpha protein level in adult muscle is developmentally-and S1 gene expression-dependent; 2. To determine the regulatory mode for the posttranscriptional suppression of EF- 1alpha protein level; 3. To investigate how S1 gene expression is related to this suppression of EF-1alpha protein abundance, and to identify responsible putative cis-element(s) and trans-factor(s); 4. Testing, in cultures, the hypothesis that muscle fibers' atrophy is due to myotube apoptosis and replicative senescence of the satellite cell population; 5. to test the hypothesis that a change from low to high EF-1alpha/S1 ratio is involved in the activation of death in cultured myotubes; and 6. To investigate the regulatory mechanism(s) governing the shift of EF-1alpha/S1 ratio from low to high during injury, long-term denervation, and aging. Studying the mechanism(s) regulating the EF-1alpha/S1 ratio will ultimately allow the design of molecular manipulation to control or slow down muscle degeneration, a condition plaguing most of the elderly.