A role for EphB and NMDARs in dendritic spine formation

描述(由申请人提供)： 中枢神经系统中大多数成熟的兴奋性突触发生在称为树突棘的特殊形态结构上，细胞培养研究表明，EphB受体酪氨酸激酶和NMDAR参与了正常的脊椎和突触的形成。最近的研究还表明，激活的EphB既可以招募NMDARs，也可以调节NMDARs的功能。这项建议的目标1将通过检查和操纵EphB基因缺失小鼠的神经元，来确定受EphB受体信号调节的树突棘形态发生的步骤。目的2将使用荧光标记的受体和双光子显微镜来评估激活的EphB在更复杂的系统中招募NMDAR的能力，即皮质切片培养。最后，已知的EphB和NMDARs的相互作用表明，EphB和NMDARs在树突棘的发育过程中发挥了协调作用；Aim 3将直接在皮质切片上测试这种合作活动，使用药理学来操纵受体功能，并使用双光子成像来可视化脊柱的形态。增加对这些分子机制的了解对于解决人类神经系统疾病至关重要，这些疾病的表型包括异常的脊柱形成，如脆性X综合征、唐氏综合症和雷特综合征。

DESCRIPTION (provided by applicant): The majority of mature excitatory synapses in the CNS occur on specialized morphologic structures known as dendritic spines, and it is clear from studies in cell culture that the EphB receptor tyrosine kinase and the NMDAR are involved in proper spine and synapse formation. Recent work has also shown that activated EphB can both recruit and modulate the function of NMDARs. Aim 1 of this proposal will determine the steps of dendritic spine morphogenesis that are regulated by EphB receptor signaling by examining and manipulating neurons over time from EphB null mice. Aim 2 will assess the ability of activated EphB to recruit NMDARs in a more complex system, cortical slice culture, using fluorescently-tagged receptors and two-photon microscopy. Finally, the known interaction of EphB and NMDARs suggests a coordinated role during the development of dendritic spines; Aim 3 will directly test for this cooperative activity in cortical slice using pharmacology to manipulate receptor function and two-photon imaging to visualize spine morphology. Increased understanding of these molecular mechanisms is critical in addressing human neurologic diseases whose phenotype include abnormal spine formation, such as Fragile X, Down, and Rett Syndromes.