Trans-synaptic coupling of phosphorylation signalling for central synapse development

正常的大脑功能依赖于称为神经递质的兴奋性或抑制性物质在称为突触的特殊粘附结构的神经元之间的转移。兴奋性突触在结构上是不对称的，神经递质从一侧（突触前侧）释放并在另一侧（突触后侧）接收，从而实现单向信息通信。这种不对称突触的发育需要突触两侧之间的粘附，然后是两侧蛋白质的差异但协调的积累。需要许多蛋白质来驱动这种突触前和突触后特化。特别是，几种蛋白质可以通过称为磷酸化的过程来修饰其他蛋白质，它们存在于发育中的突触的一侧或另一侧。为了协调突触组装，参与磷酸化的突触前和突触后蛋白的作用必须通过突触间隙连接。在这里，我们提出了一个新的研究计划，揭示兴奋性突触的结构和功能不对称的分子机制，通过调查跨突触耦合磷酸化途径。 基于我们的初步数据，我们将重点关注一种特定蛋白质对的作用：TrkC-PTP。TrkC存在于突触后，是一种可以磷酸化其他蛋白质的激酶。TrkC与突触前存在的PTP结合，并且可以使底物去磷酸化。这种蛋白质相互作用促进兴奋性突触的形成，但不知道通过哪种磷酸化信号通路发生。使用转基因小鼠，其中TrkC和PTP相互作用被废除和先进的技术，在分子和细胞生物学和生物化学，我们将确定调用的TrkC-PTP复合物在突触的信号通路，然后检查如何操纵这些通路改变突触的形成和功能。我们还将使用转基因小鼠来研究TrkC-PTP相互作用如何参与整个生物体环境中的突触发育。 该计划将测试突触发育中的一个新概念：协调的跨突触磷酸化如何驱动突触不对称。此外，由于我们将研究的一些蛋白质也涉及其他组织，对转基因小鼠的表征可能会解决有关如何确定生物不对称性的更普遍的问题。因此，该计划将在多个生物科学领域产生强大的影响。此外，由于拟议的研究将采用分子和细胞生物学，生物化学，遗传工程和电生理学的最先进的实验方法，该计划还将为加拿大的研究生和本科生提供创新的多学科培训环境。

Normal brain function relies on the transfer of excitatory or inhibitory substances called neurotransmitters between neurons at specialized adhesion structures called synapses. Excitatory synapses are structurally asymmetric with neurotransmitter released from one side (the presynaptic side) and received at the other (the postsynaptic side), enabling uni-directional information communication. The development of such asymmetric synapses requires adhesion between the two sides of the synapse followed by differential but coordinated accumulation of proteins on either side. Many proteins are needed to drive this pre- and post-synaptic specialization. In particular, several proteins that can modify other proteins through a process called phosphorylation are present on one side or the other of the developing synapse. In order to coordinate synapse assembly, the actions of the pre- and post-synaptic proteins involved in phosphorylation must be linked across the synaptic cleft. Here we propose to develop a new research program to uncover molecular mechanisms underlying structural and functional asymmetry of excitatory synapses by investigating trans-synaptically-coupled phosphorylation pathways. Based on our preliminary data, we will focus on the actions of one particular protein pair: TrkC-PTP. TrkC is present post-synaptically and is a kinase that can phosphorylate other proteins. TrkC binds to PTP which is present pre-synaptically and can de-phosphorylate substrates. This protein interaction promotes formation of excitatory synapses but it is not known through which phosphorylation signalling pathways this occurs. Using genetically modified mice in which TrkC and PTP interaction is abolished and advanced techniques in molecular and cellular biology and biochemistry, we will identify the signalling pathways invoked by the TrkC-PTP complex at synapses and then examine how manipulation of these pathways alters synapse formation and function. We will also use the genetically modified mice to investigate how TrkC-PTP interaction is involved in synapse development in a whole-organism setting. This program will test a novel concept in synapse development: how coordinated trans-synaptic phosphorylation drives synapse asymmetry. Also, because some of the proteins that we will study are also involved in other tissues, the characterization of the genetically modified mice may address more general questions about how biological asymmetry is determined. Therefore, this program will have a strong impact in multiple biological science fields. Furthermore, since the proposed study will employ state-of-the-art experimental approaches in molecular and cellular biology, biochemistry, genetic engineering and electrophysiology, this program will also provide an innovative multidisciplinary training environment for graduate and undergraduate students in Canada.