Myosin-Va and axonal protein synthesis

描述（由申请人提供）：轴突蛋白合成的证据首次发表于二十多年前。脊椎动物的轴突翻译机制被组织为轴浆周核糖体斑块（PARP），首次描述于1996年。轴突区域有自己的蛋白质合成机制的证明最初是有争议的，但现在被普遍接受。轴突蛋白质合成扩大了我们对中枢和外周轴突的正常和病理生理学的理解范围。我们对轴突功能的分析，如生长、引导、再生和可塑性，现在必须考虑依赖于局部基因表达系统的可能性。虽然轴突蛋白质合成解决了蛋白质周转的问题，但它产生了关于轴浆周围核糖体斑块中发现的蛋白质和信使RNA的稳定性和起源的新问题。在该FIRCA应用中，我们假设轴突核糖体、与它们相关的肌球蛋白- Va和/或与它们相关的信使RNA由许旺细胞供应给轴突。为了测试这一假设的前两个方面，我们将确定肌球蛋白-Va的起源（神经元或神经胶质）和编码它的转录本使用转基因小鼠，其中标记的肌球蛋白-Va在神经胶质细胞中特异性表达。第二，为了确定轴突核糖体的起源，我们将使用转基因小鼠，其中标记的核糖体蛋白在胶质细胞或神经元中特异性表达。这项研究将主要在乌拉圭的Instituto de Investigaciones Biolsgicas Clemente Estable与Josi Roberto Sotelo博士合作完成，作为NIH资助R 01 GM 066901的延伸。了解神经元轴突与雪旺细胞之间的通讯，雪旺细胞将它们包裹并髓鞘化，这对于开发损伤和疾病后再生神经系统功能的疗法至关重要。如果这个应用的基本假设是正确的，那么就有可能直接用信使RNA和蛋白质补充或编程轴突，绕过神经元细胞体，这可能高达三英尺远。

DESCRIPTION (provided by applicant): Evidence for axonal protein synthesis was first published more than two decades ago. The vertebrate axonal translational machinery is organized as periaxoplasmic ribosomal plaques (PARPs), first described in 1996. The demonstration that the axonal territory has its own protein synthesis machinery was initially controversial, but now is generally accepted. Axonal protein synthesis expands the scope of our understanding of both normal and pathological physiology of central and peripheral axons. Our analyses of axonal functions such as growth, guidance, regeneration, and plasticity must now incorporate the possibility of dependence on a local gene expression system. While axonal protein synthesis solves problems with protein turnover, it creates new questions about stability and origins of the proteins and messenger RNAs found in periaxoplasmic ribosomal plaques. In this FIRCA application, we hypothesize that the axonal ribosomes, the myosin- Va associated with them, and/or the messenger RNAs associated with them are supplied to the axon by Schwann cells. To test the first two aspects of this hypothesis, we will determine the origin (neuronal or glial) of myosin-Va and the transcript encoding it using transgenic mice in which a tagged myosin-Va is expressed specifically in glial cells. Second, to determine the origin of axonal ribosomes, we will use transgenic mice in which a tagged ribosomal protein is expressed specifically in glial cells or neurons. This research will be done primarily in Uruguay at the Instituto de Investigaciones Biolsgicas Clemente Estable in collaboration with Dr. Josi Roberto Sotelo as an extension of NIH grant R01GM066901.An understanding of the communication between the axons of neurons and the Schwann cells that ensheath and myelinate them is essential in the development of therapies to regenerate nervous system function after injury and disease. If the underlying hypothesis of this application is correct, it may be possible to directly supplement or program axons with messenger RNAs and proteins, bypassing the neuronal cell body, which can be up to three feet away.