G PROTEIN MEDIATED CONTROL OF THE NEURONAL CYTOSKELETON

描述：（申请人摘要） 神经元作为细胞没有对手 一种专门运输膜结合细胞器（MBO）的类型 沿着微管（MT）。 神经元的这种独特特征 由其独特的形态和功能特性决定。 期间 神经发生，例如，树突和轴突的形成需要 将新生质膜蛋白和脂质持续递送到 生长神经突 这些膜前体包裹在囊泡中， 其表面相关的马达分子使囊泡沿着MT移动， 神经突的远端，囊泡与神经突起融合的地方。 质膜促进神经突伸长。 在分化的神经元中， 轴突的维持同样依赖于MT。 因为轴突 缺乏蛋白质合成机制，但可以超过10,000倍， 只要它所发出的核周体的直径， 必须不断地提供新的常驻蛋白质来取代那些 老化和退化。 新的轴突蛋白质是在 周核，和许多，像那些注定要纳入 轴膜被包装在囊泡中，囊泡利用马达蛋白质进行大幅度运动， 沿着沿着MT朝向轴突终末的距离。 同样，前体 突触囊泡（SV）的最终特化产物， 神经元，从细胞体中释放出来，在那里它们被制造出来， 通过基于MT的运输到达轴突的远端。 最后，内体 前溶酶体囊泡携带降解的轴突成分， 逆行性脊髓背角中沿沿着轴突MT的胞饮性神经营养因子 方向，朝向核周体。 根据所取得的进展，此更新申请包括3个具体目标 在目前的融资期内。 1)重建的运动系统 将被起诉，以确定和描述管理层收购的监管因素 脑和肾上腺嗜铬细胞的运输，重点是 SV和嗜铬颗粒的转运。 假设MBO 运输沿着MT是调节在一个特定的方式将 得到考验 2)一种新发现的MT复合物的结构， 蛋白磷酸酶2A（PP 2A）。 一个假设是 测试的是，MT结合的PP 2A通过以下方式调节MBO沿MT的沿着转运： 控制运输成分的磷酸化状态 机械或通过调节MT稳定性。 3)多边贸易体制的作用 将测试保持小窝的结构。 新的数据显示 小窝蛋白是小窝的一种常驻蛋白， 在质膜和高尔基体之间通过一种机制， MT用于向高尔基体运输，而不是远离高尔基体。 测试将是 这是基于这样一种假设，即其他常驻小窝蛋白也 通常在质膜和高尔基体之间通过MT- 依赖循环 动力蛋白是运输发动机的假说 的小窝蛋白的高尔基体也将被测试，和机制， 小窝蛋白从高尔基体转运回质膜将是 测定

DESCRIPTION: (Applicant's Abstract) The neuron has no rival as a cell type that specializes in transport of membrane-bounded organelles (MBOs) along microtubles (MTs). This distinctive trait of the neuron is dictated by its unique morphological and functional properties. During neurogenesis, for example, the formation of dendrites and axons requires sustained delivery of nascent plasma membrane proteins and lipids into growing neurites. These membrane precursors are packages in vesicle whose surface-associated motor molecules move the vesicle along MTs to the distal tips of neurites, where fusion of the vesicles with the plasma membrane promotes neurite elongation. In differentiated neurons, the maintenance of axons is equally reliant upon MTs. Because the axon lacks protein synthesis machinery, but can be more than 10,000 times as long as the diameter of the perikaryon from which it emanates, the axon must constantly be supplied with new resident proteins to replace those that age and degrade. New axonal proteins are synthesized in the perikaryon, and many, like those destined for incorporation into the axolemma, are packaged in vesicles that use motor proteins to move great distances along MTs toward the axon terminal. Likewise, the precursors of synaptic vesicles (SVs), the ultimate specialized products of neurons, are delivered from the cell body, where they are manufactured, to the distal end of the axon by MT- based transport. Finally, endosomal and pre-lysosomal vesicles carry degraded axonal components and edocytosed neurotrophic factors along axonal MTs in the retrograde direction, toward the perikaryon. This renewal application comprises 3 Specific Aims based on progress made during the present funding period. 1) Reconstituted motility systems will be sued to identify and characterize regulatory factors for MBO transport in brian and adrenal chromaffin cells, with emphasis on transport of SVs and chromaffin granules. The hypothesis that MBO transport along MTs is regulated in an organelle-specific manner will be tested. 2) The structure of a newly discovered complex of MTs and protein phosphatase 2A (PP2A) will be determined. A hypothesis to be tested is that MT-bound PP2A regulates MBO transport along MTs by controlling the phosphorylation state of components of the transport machinery or by regulating MT stability. 3) The role of MTs in maintaining the structure of caveolae will be tested. New data indicate that caveolin, a resident protein of caveolae, cycles constitutively between the plasma membrane and the Golgi by a mechanism that requires MTs for transport toward, but not away from the Golgi. A test will be made of the hypothesis that other resident caveolar proteins also normally more between the plasma membrane and the golgi by a MT- dependent cycle. The hypothesis that dynein is the motor for transport of caveolin to the golgi will be also tested, and the mechanism for caveolin transport from the Golgi back to the plasma membrane will be determined.