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

描述（由申请人提供）：这些研究的长期目标是深入了解反粘着分子对少突胶质细胞功能的作用。由基质细胞蛋白质家族介导的反粘附作用涉及细胞转化为有利于与运动相关的细胞功能的中间粘附状态。尽管在髓鞘形成过程中有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。我们假设，基于我们的初步数据，磷酸二酯酶-Ia/自分泌运动因子[PD-Ia/ATX（NPP-2）]是由少突胶质细胞释放的，作为迄今为止未表征的细胞外基质的基质细胞组分，其调节迁移后少突胶质细胞的粘附状态，从而决定其过程重塑能力，从而决定髓鞘形成的总体效率。在具体目标1中，我们将研究金属蛋白水解活性在产生可溶性少突胶质细胞衍生的PD-Ia/ATX中的作用，因为它是这种II型跨膜蛋白的可溶形式，在髓鞘形成起始期间表现出功能活性。在具体目标2中，我们将确定与其他基质细胞蛋白相似的细胞因子相关机制在多大程度上有助于PD-Ia/ATX对少突胶质细胞的反趋化作用。在这些实验中，我们将确定功能性活性整合素的参与、细胞骨架蛋白的再分布和Rho-GTP酶对PD-Ia/ATX介导的反粘连的激活。在具体目标3的实验中，我们将确定过程增生/重塑以及髓鞘膜和鞘形成直接依赖于PDIa/ATX表达水平的程度。在这些研究中，我们将分析PD-Ia/ATX过表达和表达不足的少突胶质细胞在体外产生复杂的过程形态和髓鞘膜结构的能力，以及在体内在髓鞘形成障碍小鼠突变体shiverer的脑中形成髓鞘轴突的能力。 此外，我们将表征转基因小鼠，其中少突胶质细胞过表达PD-Ia/ATX。这些研究将提供新的见解，决定中枢神经系统髓鞘形成的分子机制，他们可能有助于开发新的治疗策略，旨在改善髓鞘再生的病理条件下。

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.