Gpr56 is a regulator of glial cell development and myelination

描述（由申请人提供）：髓磷脂是一种多层，富含脂质的膜，在脊椎动物神经系统中隔离轴突，促进动作电位的快速传导。髓磷脂是由特殊的胶质细胞——周围神经系统的雪旺细胞（SCs）和中枢神经系统的少突胶质细胞（OLs）产生的。两种类型的细胞都是通过在轴突周围延伸和反复包裹质膜形成髓鞘，而胶质细胞的细胞质被挤压，最终形成髓鞘。此外，髓鞘胶质通过为它们所包裹的轴突提供重要的营养支持来促进神经元的健康。髓鞘受损是许多严重神经系统疾病的原因，如多发性硬化症和沙克-玛丽-图斯病，髓鞘的丧失会导致神经元的丧失，最终导致瘫痪。尽管髓磷脂对人类生命至关重要，但神经胶质细胞发育和髓鞘形成的分子机制尚不清楚。为此，我们寻求识别和表征新的髓鞘形成的调节。我们最近确定粘附gpcr (aGPCR) Gpr126对SC髓鞘形成至关重要。粘附- gpcr的特点是存在一个大的n端，通常富集与细胞-细胞/细胞-基质相互作用相关的结构域。agpcr在促进细胞间相互作用和细胞内信号传导能力方面的双重作用，以及Gpr126对SC髓鞘形成的重要性，使我们假设额外的agpcr可能调节胶质细胞的发育和髓鞘形成。我们已经确定Gpr56，一种与Gpr126相关的aGPCR，在髓鞘胶质细胞中高表达，我们对斑马鱼和小鼠突变体的初步分析表明，Gpr56是OL和SC髓鞘形成的重要调节因子。在这个提议中，我们试图确定Gpr56在髓鞘胶质细胞中的作用。在第一个目标中，我将使用我使用转录激活因子样效应物核酸酶生成的两个Gpr56斑马鱼突变体来测试Gpr56是少突胶质细胞发育和髓鞘形成所必需的假设。除了传统的分子和超微结构技术，我将利用斑马鱼的光学清晰度

DESCRIPTION (provided by applicant): Myelin is a multilamellar, lipid-rich membrane that insulates axons in the vertebrate nervous system to facilitate the rapid conduction of action potentials. Myelin is generated by specialized glial cells - Schwann cells (SCs) in the peripheral nervous system and oligodendrocytes (OLs) in the central nervous systems. Both cell types form myelin by extending and iteratively wrapping their plasma membranes around axons, and glial cell cytoplasm is extruded to ultimately form the myelin sheath. In addition, myelinating gli promote neuronal health by providing vital trophic support to the axons they ensheath. Impaired myelination is the cause of many severe neurological disorders such as multiple sclerosis and Charcot-Marie-Tooth disease, and loss of myelin can lead to neuronal loss and eventual paralysis. Although myelin is essential for human life, the molecular mechanisms that underlie glial cell development and myelination are poorly understood. To this end, we seek to identify and characterize novel regulators of myelination. We recently determined that the adhesion-GPCR (aGPCR) Gpr126 is essential for SC myelination. Adhesion-GPCRs are characterized by the presence of a large N-terminus often enriched for domains associated with cell-cell/cell-matrix interactions. The dual roles of aGPCRs in facilitating cell-cell interactions and their intracellular signaling capacity, in addition to the importance of Gpr126 for SC myelination, led us to hypothesize that additional aGPCRs may regulate glial cell development and myelination. We have determined that Gpr56, an aGPCR related to Gpr126, is highly expressed in myelinating glia, and our preliminary analyses of zebrafish and mouse mutants indicate that Gpr56 is an important regulator of OL and SC myelination. In this proposal, we seek to define the role of Gpr56 in myelinating glia. In the first aim, I will test the hypothesis that Gpr56 is required for oligodendrocyte development and myelination using two gpr56 zebrafish mutants I generated using Transcription Activator-Like Effector Nucleases. In addition to traditional molecular and ultrastructural techniques, I will take advantage of the optical clarity of zebrafish by performing time-lapse imaging to determine how loss of gpr56 function affects glial cell behavior in living embryos. In the second aim, I will test the hypothesis that Gpr56 is required fo SC development and myelin maintenance. To this end, we will examine the consequences of Gpr56 loss of function using immunohistochemical and ultrastructural approaches in both zebrafish and mouse mutants. In the third aim, we will employ a structure-function based strategy to determine which functional domains (signaling versus adhesion) are necessary for Gpr56 regulation of OL and SC myelination. Specifically, we will test the ability of single functional domains (N- terminus versus C-terminus) to rescue gpr56 mutant phenotypes. Together, these experiments will define the role of Gpr56 in SC and OL myelination and myelin maintenance and will broaden our basic understanding of aGPCR biology and the molecular mechanisms that control myelination.