Src hypoactivity as a mediator of various molecular alterations leading to NMDAR

 描述(由申请人提供)：N-甲基-D-天冬氨酸(NMDA)受体功能低下假说是精神分裂症(SCZ)病理生理学的主要假设之一，并得到了大量药理学、行为学和遗传学研究的支持。然而，我们对SCZ患者NMDAR信号的具体变化及其机制基础知之甚少。这是一个严重的知识鸿沟，阻碍了这一假说的进一步发展，并限制了我们确定具体治疗干预措施的努力。(初步数据)作为NMDA受体(NMDAR)信号改变的直接证据，我们发现SCZ患者死后背外侧前额叶皮质(DLPFC)NMDAR亚单位2(GluN2)酪氨酸磷酸化水平降低，下游信号减少。这些变化与NMDAR的减少无关，而是与一系列的激酶--Src激酶、蛋白激酶C和PYK2--的活性降低有关，它们共同降低了GluN2酪氨酸的磷酸化水平。我们在SCZ患者的DLPFC中发现了多个分子改变：PSD-95增加，ERBB4活性增加，debindin-1和RPTPA减少，每一种都可以导致Src活性低下。(假设)我们假设NMDAR复合体中Src的活性低下(Src-NR)减少了谷氨酸酪氨酸的磷酸化，并且是由Src-NR相关蛋白网络(Src-NR互动体)中改变的蛋白质相互作用引起的，这可以被用来改变NMDAR活性低下的行为表型。(方法)我们提出了一种人-啮齿动物翻译策略，通过该策略，我们分析了死后大脑中与疾病相关的变化，并在啮齿动物研究中探讨了其潜在的机制。Aim 1将进一步研究老年和中年SCZ人群的死后脑，以确定SCZ中Src-NR相互作用组的分子变化，Aim 2将确定蛋白质相互作用在Src-NR活性低下中的作用，并在啮齿动物和人类身体组织的体外准备中测试救援策略，Aim 3将确定Src-/-小鼠的SCZ相关行为和脑电表型，并测试Src增强是否可以在体内挽救这些表型。

 DESCRIPTION (provided by applicant): The N-methyl-D-aspartate (NMDA) receptor hypofunction hypothesis is one of the leading postulates for the pathophysiology of schizophrenia (SCZ) and is supported by numerous pharmacologic, behavioral and genetic studies. Nevertheless, we have little insight into specific alterations in NMDAR signaling and its mechanistic basis in SCZ patients. This is a critical knowledge gap, which has impeded further development of this hypothesis and limited our efforts to identify specific therapeutic interventions. (Preliminary Data) As direct evidence for altered NMDA receptor (NMDAR) signaling, we found decreased NMDA/Glycine induced tyrosine phosphorylation of NMDAR subunit 2 (GluN2) and reduced downstream signaling in the postmortem dorsal lateral prefrontal cortex (DLPFC) of SCZ cases. These changes are not associated with decreased NMDARs but with reduced activity of a cascade of kinases- Src kinase, protein kinase C and Pyk2- which in concert decrease GluN2 tyrosine phosphorylation. We found multiple molecular alterations in the DLPFC of SCZ cases; increased PSD-95, increased erbB4 activity, decreased dysbindin -1 and RPTPa, each of which can induce Src hypoactivity. (Hypotheses) We hypothesize that hypoactivity of Src in the NMDAR complex (Src-NR) reduces GluN tyrosine phosphorylation and is caused by altered protein interactions in a network of Src-NR-associated proteins ( the Src-NR interactome), which can be leveraged to modify behavioral phenotypes of NMDAR hypoactivity. (Approach) We propose a human-rodent translation strategy, by which we analyze disease related alterations in postmortem brains and examine their underlying mechanisms in rodent studies. Aim 1 will further examine postmortem brains of an elderly and mid-life SCZ cohorts to identify molecular alterations in the Src-NR interactome in SCZ, Aim 2 will determine the role of protein interactions in Src-NR hypoactivity and test rescue strategies in ex vivo preparations of rodent and human postmortem tissues and Aim 3 will determine SCZ related behavior and EEG phenotypes of Src-/- mice and test if Src enhancement can rescue such phenotypes in vivo.