The COPA vesicle protein and pathogenesis of spinal muscular atrophy

摘要 运动神经元和肌肉功能障碍在脊肌萎缩症(SMA)中的发病机制 婴儿死亡的原因仍未解决。SMA由低水平的存活运动神经元SMN引起 蛋白。这些实验背后的理论基础是我们发现SMN蛋白结合并移动 与七聚体COPI辅酶复合体的最大组成部分CopA蛋白一起存在于神经元中。 这项建议的目的是确定减少SMN相互作用的分子机制 伴随着COPI复合体和COPI活性的丧失，导致神经退行性变。高尔基体衍生的COPI囊泡 在高尔基人之间进行蛋白质和其他货物的翻译后加工和运输所必需的 内质网和内质网及分泌途径。在SMA中观察到了高尔基体的变化， 肌萎缩侧索硬化症、阿尔茨海默病和其他神经退行性疾病。我们的数据 证明病理性低水平的SMN改变高尔基体的形态和功能 仪器。这项提议的总体前提是，COPI综合体是加工和 运输对正常运动神经元维持至关重要的货物。我们还展示了具体的 发现了与COPI相关的mRNAs。在这项赠款中强调的一类货物是被选中用于 轴突运输。我们提出了遗传、生化、蛋白质组学和转基因方法来定义 COPI复合体的性质和活性及其与SMN和其他潜在结合的相互作用 合伙人。我们将建立小鼠模型来研究COPI在神经元中的作用，并进行相关的 轴突发生、RNA转运和病理生物学结果的活体研究。因为SMN在物理上 与与其他神经退行性疾病有关的因素相互作用，从而暗示因果关系的共性， 这些实验应该会对这些疾病中发生的异常过程产生新的见解。 此外，药物诱导COPI通路可能代表了治疗SMA的新目标 以及其他神经退行性疾病。

ABSTRACT The pathogenesis of motor neuron and muscle dysfunction in spinal muscular atrophy (SMA), a leading genetic cause of infant mortality, is still unresolved. SMA results from low levels of the Survival Motor Neuron SMN protein. The rationale underlying these experiments is our discovery that the SMN protein binds to and moves in neurons together with the CopA protein, the largest constituent of the heptameric COPI coatomer complex. The objective of this proposal is to determine the molecular mechanisms by which reduced SMN interaction with COPI complex and loss of COPI activities leads to neurodegeneration. Golgi-derived COPI vesicles are necessary for post-translational processing and transport of proteins and other cargoes between Golgi apparatus and endoplasmic reticulum and secretory pathway. Golgi alterations have been observed in SMA, amyotrophic lateral sclerosis, Alzheimer’s disease, and other neurodegenerative disorders. Our data demonstrate that pathologically low levels of SMN alter the morphology and functionality of the Golgi apparatus. The overall premise of this proposal is that the COPI complex is necessary for processing and trafficking of cargoes essential for normal motor neuron maintenance. We have also shown that specific mRNAs are found in association with COPI. One class of cargo emphasized in this grant is mRNA selected for axonal transport. We propose genetic, biochemical, proteomic and transgenic approaches to define the properties and activities of the COPI complex and its interactions with SMN and other potential binding partners. We will create murine models to investigate the role of COPI in the neuron and perform correlative in vivo studies of axonogenesis, RNA trafficking and pathologic biological outcomes. Because SMN physically interacts with factors linked to other neurodegenerative diseases, thereby implicating commonality of causality, these experiments should result in new insights into the aberrant processes occurring in these disorders. Moreover, pharmacologic induction of the COPI pathway may represent a novel objective for treatment of SMA and other neurodegenerative diseases.