Mechanisms in CNS myelination: Role of PD-Ialpha/ATX

描述(申请人提供)：这些研究的长期目标是深入了解对应性黏附分子对少突胶质细胞功能的作用。由基质细胞蛋白家族介导的反黏附参与了细胞向中间黏附状态的转变，这种黏附状态有利于与运动相关的细胞功能。尽管在髓鞘形成过程中发生了各种各样的运动事件，但基质细胞蛋白的参与还没有被表征。根据我们的初步数据，我们假设，磷酸二酯酶-Ia/自体趋化蛋白[PD-Ia/ATX(NPP-2)]是由少突胶质细胞释放的，作为迄今尚未鉴定的细胞外基质的基质成分，它调节迁移后少突胶质细胞的黏附状态，从而决定它们的过程重塑能力，从而决定髓鞘形成的整体效率。在特定的目标1中，我们将研究金属蛋白分解活性在可溶的、少突胶质细胞来源的PD-Ia/ATX产生中的作用，因为它是这种II型跨膜蛋白的可溶形式，在髓鞘形成开始时表现出功能活性。在特定的目标2中，我们将确定与细胞骨架相关的机制，类似于观察到的其他基质蛋白，在多大程度上有助于PD-Ia/ATX对少突胶质细胞的反黏附作用。在这些实验中，我们将确定功能性活性整合素的参与、细胞骨架蛋白的重新分布以及Rho-GTP酶在PD-Ia/ATX介导的抗黏附中的激活。在针对特定目标3的实验中，我们将确定生长/重塑和髓鞘形成过程在多大程度上直接依赖于PDIA/ATX的表达水平。在这些研究中，我们将分析PD-Ia/ATX高表达和低表达的少突胶质细胞在体外产生复杂的突起形态和髓鞘膜结构的能力，以及在体内髓鞘脱失突变颤抖小鼠脑内形成髓鞘轴突的能力。此外，我们还将研究少突胶质细胞过表达PD-1a/ATX的转基因小鼠。这些研究将为决定中枢神经系统髓鞘形成的分子机制提供新的见解，并可能有助于开发新的治疗策略，旨在改善病理条件下的髓鞘再分化。

DESCRIPTION (provided by applicant): The long-term goal of these studies is to gain insight into the role of counteradhesive molecules for oligodendrocyte function. Counteradhesion, mediated by the family of matricellular proteins, has been implicated in the transformation of cells into intermediate adhesive states that favor cellular functions related to locomotion. Despite of a variety of locomotive events during myelin sheath formation, the involvement of matricellular proteins has not been characterized. We hypothesize, based on our preliminary data, that phosphodiesterase-Ia/autotaxin [PD-Ia/ATX (NPP-2)] is released by oligodendrocytes as a hitherto uncharacterized matricellular component of the extracellular matrix that regulates the adhesive state of post-migratory oligodendrocytes and consequently determines their process remodeling capacity and thus the overall efficiency of myelin sheath formation. In, specific aim 1, we will investigate the role of metalloproteolytic activities in the generation of soluble, oligodendrocyte-derived PD-Ia/ATX, since it is the soluble form of this type II transmembrane protein that appears functionally active during myelination initiation. In specific aim 2, we will determine the extent to which cytoskeleton-related mechanisms, similar to the ones observed for other matricellular proteins, contribute to PD-Ia/ATX's counteradhesive effect toward oligodendrocytes. In these experiments, we will determine the involvement of functional active integrins, the redistribution of cytoskeletal proteins and the activation of Rho-GTPases for PD-Ia/ATX mediated counteradhesion. In the experiments to specific aim 3, we will determine the extent to which process outgrowth/remodeling and myelin membrane and sheath formation is directly dependent on PDIa/ATX expression levels. In these studies we will analyze PD-Ia/ATX over- and under-expressing oligodendrocytes for their capacity to generate complex process morphologies and myelin membrane structures in vitro and to myelinate axons in vivo in the brain of the dysmyelinating mouse mutant shiverer. In addition, we will characterize transgenic mice, in which oligodendrocytes over-express PD-la/ATX. These studies will provide novel insight into the molecular mechanisms that determine CNS myelination, and they may contribute to the development of novel therapeutic strategies designed to improve remyelination under pathological conditions.