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

 描述（由申请方提供）：N-甲基-D-天冬氨酸（NMDA）受体功能减退假说是精神分裂症（SCZ）病理生理学的主要假设之一，并得到许多药理学、行为学和遗传学研究的支持。然而，我们对SCZ患者中NMDAR信号的具体改变及其机制基础知之甚少。这是一个关键的知识差距，阻碍了这一假设的进一步发展，并限制了我们确定具体治疗干预措施的努力。（初步数据）作为改变的NMDA受体（NMDAR）信号传导的直接证据，我们发现在SCZ病例的死后背外侧前额叶皮质（DLPFC）中，NMDA/甘氨酸诱导的NMDAR亚基2（GluN 2）的酪氨酸磷酸化减少，下游信号传导减少。这些变化与NMDAR减少无关，但与激酶级联- Src激酶、蛋白激酶C和Pyk 2-的活性降低有关，这会降低GluN 2酪氨酸磷酸化。我们在SCZ病例的DLPFC中发现了多种分子改变; PSD-95增加，erbB 4活性增加，dysbindin-1和RPTPa减少，每一种都可以诱导Src活性低下。（假设）我们假设NMDAR复合物（Src-NR）中Src的低活性降低了GluN酪氨酸磷酸化，并且是由Src-NR相关蛋白网络（Src-NR相互作用组）中蛋白质相互作用的改变引起的，这可以用来改变NMDAR低活性的行为表型。（方法）我们提出了一种人类-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改变，并在啮齿动物研究中研究了其潜在机制。目的1将进一步检查老年和中年SCZ队列的死后脑，以鉴定SCZ中Src-NR相互作用组的分子改变，目的2将确定蛋白质相互作用在Src-NR活性减退中的作用，并在啮齿动物和人死后组织的离体制备物中测试拯救策略，目的3将确定Src-/-的SCZ相关行为和EEG表型。小鼠并测试Src增强是否可以在体内拯救这样的表型。

 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.