Wnt Signaling in Synaptic Prepattern formation and Motor Axon Guidance

突触前模式形成和运动轴突引导中的 Wnt 信号转导

• 批准号: 8002018
• 负责人: Laura R. Gordon
• 金额: $ 2.87万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-12-01 至 2011-08-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8002018
• 关键词: Affect; Agrin; Antibodies; Autoimmune Process; Axon; Binding; Biological Assay; Cell Polarity; Cells; Cholinergic Receptors; Congenital Myasthenic Syndromes; Data; Development; Dominant-Negative Mutation; Drosophila genus; Embryo; Genetic; Goals; Growth Cones; Hair Cells; Health; Human; Imaging Techniques; In Vitro; Laboratories; Life; Ligands; Mediating; Microscopy; Molecular; Motor; Muscle; Muscle Cells; Muscle Fibers; Muscle-Specific Kinase; Mutation; Myasthenia Gravis; Nerve; Neuromuscular Diseases; Neuromuscular Junction; Orthologous Gene; Pathway interactions; Phenotype; Play; Process; Proteins; Research; Role; Signal Pathway; Signal Transduction; Site; Specificity; Spinal Cord; Surface; Synapses; System; Testing; Wing; Zebrafish; axon growth; axon guidance; axonal guidance; cell type; human MUSK protein; human disease; in vivo; member; mutant; neuromuscular; overexpression; peripheral membrane protein 43K; promoter; receptor; research study; response; time use

DESCRIPTION (provided by applicant): The overlying goal of this project is to determine the developmental mechanisms by which neuromuscular junctions are initially formed. One key molecular player in the development of the neuromuscular junction is the transmembrane receptor unplugged/MuSK. Unplugged/MuSK is specifically expressed in muscle fibers and controls two aspects of neuromuscular junction formation; the clustering of "prepatterned" acetylcholine receptors (AChRs) on the muscle fiber prior to the arrival of the nerve and the guidance of the motor nerve to its proper muscle target. Later in development it also directs the formation of mature neuromuscular synapses. With the following three aims I propose to determine how unplugged/MuSK spatially coordinates clustering of "prepatterned" AChRs and growth cone guidance to the muscle center. First, I will investigate if multiple Wnt signals activate the unplugged/MuSK receptor. We have previously identified wnt11r as an unplugged/MuSK ligand, but we suspect that wnt4a is also playing a role in unplugged/MuSK activation. I will use a combination of genetic interaction and in-vivo binding experiments to examine the extent of cooperation between the two Wnts and their ability to bind unplugged/MuSK. Second, I will determine which molecular players are downstream of unplugged/MuSK and whether the signaling cascade is similar to the Wnt planar cell polarity cascade. Activation of a planar cell polarity-like pathway could establish a central zone in the muscle fiber that dictates where AChR clusters initially form and where motor axons extend when they enter the muscle territory. I will investigate the involvement of various planar cell polarity components by disrupting their function in muscle fibers and determining whether this results in unplugged- like AChR clustering and axonal guidance errors. Third, in many systems including the Drosophila wing disk, cellular polarity is initially established by asymmetric localization of various members of the planar cell polarity pathway. I propose to determine the localization of these planar cell polarity components in muscle fibers and also determine whether the absence of Wnt signaling affects this localization using in-vivo live confocal imaging techniques. PUBLIC HEALTH RELEVANCE: This research is directly relevant to the study of human diseases in that MuSK is a target of antibody- mediated autoimmune attack in the neuromuscular disease myasthenia gravis. Furthermore, mutations in components of the MuSK pathway are responsible for human congenital myasthenic syndromes.

描述（由申请人提供）：该项目的上层目标是确定最初形成神经肌肉连接的发育机制。神经肌肉连接开发中的一个关键分子参与者是跨膜受体解开/麝香。未插入/麝香在肌肉纤维中特别表达，并控制神经肌肉结的两个方面。在神经到达之前，肌肉纤维上的“预一式”乙酰胆碱受体（ACHR）的聚类以及运动神经的指导到其适当的肌肉靶标。后来，它还指导成熟的神经肌肉突触的形成。通过以下三个目标，我建议确定如何在空间上划分/麝香在肌肉中心的“预一览” ACHR和生长锥引导的聚类中如何坐在空间上。首先，我将研究多个WNT信号是否激活了插电/麝香受体。我们以前曾将WNT11R识别为插入/麝香配体，但我们怀疑Wnt4a也在拔下/麝香激活中发挥作用。我将使用遗传相互作用和体内结合实验的组合来检查两个WNT之间的合作程度及其结合插电/麝香的能力。其次，我将确定哪些分子玩家在未插电/麝香的下游，以及信号级联是否类似于Wnt Planar Planar Pallity Cascade。平面细胞极性途径的激活可以在肌肉纤维中建立一个中央区域，该区域决定了ACHR簇最初形成的位置以及运动轴突进入肌肉区域时延伸的位置。我将通过破坏其在肌肉纤维中的功能并确定这是否会导致拔出的ACHR聚类和轴突引导误差来研究各种平面细胞极性成分的参与。第三，在包括果蝇翼磁盘在内的许多系统中，最初通过对平面细胞极性途径的各种成员的不对称定位来确定细胞极性。我建议确定这些平面细胞极性成分在肌肉纤维中的定位，还确定使用Wnt信号的缺失是否使用Vivo In-Vivo Live共聚焦成像技术影响了这种定位。公共卫生相关性：这项研究与对人类疾病的研究直接相关，因为麝香是神经肌肉疾病肌无力肌无力肌无力的抗体介导的自身免疫性攻击的靶标。此外，麝香途径的组成部分的突变是人类先天性疗法综合征的原因。