AXONAL TRANSPORT IN NF AND SOD1 TRANSGENIC MICE

描述（改编自申请人摘要）： 神经元通过不断地向轴突提供 在细胞体内合成的大分子。这种供应是持续的 通过轴突运输的机制， 大分子以不同的速度传递到远端轴突。在 神经系统疾病，这种运输可能会失败，无论是作为一个主要的 疾病的原因或由其他原发性疾病引起的结果 缺陷在任何一种情况下，神经元变性都会加剧。 大量证据表明，运动神经元存在轴突运输缺陷， 神经元疾病，导致神经丝和其他 近端轴突和细胞体中的细胞器。拟定研究 利用现有的转基因小鼠来测试三种特定的 关于轴突运输的假说。长期目标是 进一步了解轴突运输机制，在正常和 病理状态。 第一个假设是NF-H减慢了NFs和其他神经递质的轴突运输。 通过稳定细胞骨架网络， 神经纤维轴突运输的正常速率由平衡的 三种NF亚基的比例。为了验证这一假设， 将在多种转基因小鼠中测量慢轴突转运 表达不同NF亚基水平升高。第二 一种假说是轴突细胞骨架网络阻碍了运动 因此，在决定细胞器的功能方面起着重要的作用。 不同细胞器的运输速率。为了验证这一假设， 不同蛋白质组的快速轴突运输速率（相关 具有不同的细胞器）将在具有升高的 最后，第三个假设是， 运动神经元病中神经纤维和膜性细胞器的积累 是由轴突运输缺陷引起的为了验证这一假设， 将在小鼠中测量快速和慢速轴突运输的速率 由于突变的Cu/Zn表达而发展为运动神经元疾病 超氧化物歧化酶（SOD 1）。 将使用经典范例测量轴突运输速率 其中放射性氨基酸（35 S-甲硫氨酸）被递送至 紧邻神经元细胞体。由于氨基酸是 整合到新合成的蛋白质中，这些蛋白质的运输 将在不同的时间点监测沿着轴突的沿着蛋白质。

DESCRIPTION (Adapted from applicant's abstract) : Neurons maintain their axons by constantly supplying them with macromolecules synthesized in the cell body. This supply is sustained by mechanisms of axonal transport, which move different groups of macromolecules to the distal axon at different velocities. In neurological diseases, this transport could fail either as a primary cause of the disease or as a consequence induced by other primary defects. In either case neuronal degeneration would be exacerbated. Ample evidence suggest that defective axonal transport exists in motor neuron disease, leading to the accumulation of neurofilaments and other organelles in the proximal axons and cell bodies. The proposed study takes advantage of existing transgenic mice to test three specific hypotheses regarding axonal transport. The long term objective is to further understand mechanisms of axonal transport in both normal and pathological states. The first hypothesis is that NF-H slows axonal transport of NFs and other cytoskeletal components by stabilizing the cytoskeletal network and that the normal rate of axonal transport of NFs is determined by a balanced ratio of the three NF subunits. To test this hypothesis, the rate of slow axonal transport will be measured in a variety of transgenic mice that express elevated levels of different NF subunits. The second hypothesis is that the axonal cytoskeletal network hinders the movement of organelles, and thus, plays a significant role in determining the rates of transport of different organelles. To test this hypothesis, the fast axonal transport rates of different groups of proteins (associated with different organelles) will be measured in mice that have elevated NF densities and crossbridges, Finally, the third hypothesis is that accumulation of NFs and membranous organelles in motor neuron disease is caused by defects in axonal transport. To test this hypothesis, the rate of both fast and slow axonal transport will be measured in mice that develop motor neuron disease due to expression of a mutant Cu/Zn superoxide dismutase (SOD1). The axonal transport rates will be measured using a classical paradigm in which a radioactive amino acid (35S-methionine) is delivered to the immediate vicinity of neuronal cell bodies. As the amino acid is incorporated into newly synthesized proteins, the transport of these proteins along the axons will be monitored at different time points.