REGULATION OF NMDA RECEPTOR CLUSTERING BY EPH KINASES

这个项目的目标是描述在发育中的大脑中调节突触发生的信号通路。以往的研究表明，突触的分化有一系列步骤，其中之一是突触后神经递质受体的聚集。在神经肌肉连接处，胆碱能受体的聚集是由蛋白多糖(Agrin)诱导的，它激活了受体酪氨酸激酶(Musk)。在中枢神经系统中，尚不清楚是什么调节了突触后受体的聚集，如兴奋性突触上的NMDA受体。发起人实验室的初步数据显示，在培养的海马神经元上，Eph受体酪氨酸激酶的激活诱导了NMDA受体亚单位NR1的聚集。此外，Eph受体配基(肾上腺素)可诱导Eph和NMDA受体之间的生化相互作用。这项研究将通过三个特定的目的来研究蛋白质-蛋白质之间的相互作用，这些蛋白质通过三个特定的目的来介导eaffin诱导的NMDA受体聚集。首先，我们将确定Eph和NR1受体的结构域，这些结构域对eaffin诱导的受体聚集至关重要。然后，我们将研究酪氨酸磷酸化在Eph酪氨酸激酶聚集NMDA受体中的作用。最后，将通过两组实验来检验NMDA受体聚集的细胞机制。我们将在细胞膜上展示肾上腺素配体，并确定它们对邻近神经元上NMDA受体的影响。突触形成的机制是儿科神经学家特别感兴趣的，因为异常的突触形成可能是常见的发育障碍，如智力低下和癫痫的基础。通过在迈克尔·格林伯格博士的指导下接受基础科学的强化培训，以及在波士顿儿童医院进行儿科神经病学的临床实践，这位候选人有望成为一名内科科学家，拥有研究儿童神经元发育不全的分子和细胞工具。

The goal of this project is to characterize the signaling pathways that regulate synaptogenesis in the developing brain. Previous studies have demonstrated that synapses differentiate in a series of steps, one of which is the clustering of postsynaptic neurotransmitter receptors. In the neuromuscular junction, clustering of the cholinergic receptors is induced by a proteoglycan (agrin), which activates a receptor tyrosine kinase (MuSK). In the central nervous system, it is not clear what regulates the clustering of postsynaptic receptors such as the NMDA receptors at excitatory synapses. Preliminary data from the Sponsor's laboratory indicate that activation of Eph receptor tyrosine kinases on cultured hippocampal neurons induces the clustering of a NMDA receptor subunit, NR1. Furthermore, Eph receptor ligands (ephrins) induce a biochemical interaction between the Eph and NMDA receptors. This study will examine the protein-protein interactions that mediate ephrin-induced NMDA receptor clustering through three specific aims. First, we will identify the domains of Eph and NR1 receptors that are critical for ephrin-induced receptor clustering. Then, we will investigate the role of tyrosine phosphorylation on the clustering of NMDA receptors by Eph tyrosine kinases. Finally, the cellular mechanisms of NMDA receptor clustering will be examined through two sets of experiments. We will present the ephrin ligands on the cell membrane and determine their effect on the NMDA receptors on neighboring neurons. Mechanisms of synapse formation are of particular interest to pediatric neurologists because aberrant synapse formation is likely to underlie common developmental disorders such as mental retardation and epilepsy. Through intensive training in basic science under the supervision of Dr. Michael Greenberg and clinical practice in pediatric neurology at the Children's Hospital in Boston, the candidate expects to become a physician- scientist equipped with the molecular and cellular tools to study neuronal dysgenesis in children.