Synaptic Protein Networks, Genetic Risk, and Spine Loss in Schizophrenia

摘要 精神分裂症（Sz）是一种终身和毁灭性的精神疾病，治疗选择有限，无法治愈。 在精神分裂症的多个脑区反复观察到第3层锥体细胞树突棘缺失 (Sz)包括初级听觉皮层（AI）。脊椎缺失被认为是初级听觉皮层的基础 在Sz中观察到的处理缺陷，导致Sz中的社会认知受损和幻听。 我们已经表明，只有较小的脊椎在Sz Al层3中丢失。双光子活体成像研究进展 已经表明，新的棘很小，对突触的形成至关重要，并且是成年人新的学习所必需的。 动物突触蛋白网络（SynPN）调控树突棘的形成、稳定和可塑性 特征，如蛋白质表达，运输和磷酸化（Phos），以及大量的Sz风险 基因座编码突触蛋白。 靶向和鸟枪质谱（MS）方法发现突触体和Phos Sz.这些变化没有用相应的变化来解释 在这些蛋白质的匀浆水平，表明在Sz SynPN病理的冲击是由 蛋白质表达以外的过程（例如蛋白质运输和活性）。八种蛋白质上的九个Phos位点 与突触体蛋白水平和小棘密度高度相关。除了这8个之外 蛋白质在突触后谷氨酸受体和棘突的囊泡运输中具有良好的记录作用， 调控突触后谷氨酸信号传导是遗传学中最重要的参与途径之一， Sz的研究。因此，我们假设：突触后蛋白的异常运输和Phos是相关的 Sz基因风险和驱动小脊柱损失在Sz铝。 我们将在一组前所未有的平行基因组学、蛋白质组学和显微镜检查中检验这一假设。 在100名Sz和100名匹配的对照受试者中进行的实验，使用尖端的计算分析来识别 蛋白质和Phos与Sz遗传学相关，并产生疾病的因果模型（目的1）。我们将利用 创新的分子和双光子显微镜方法来测试候选Phos的影响，从我们的 初步研究和高优先级目标1的结果，对棘密度，大小，形成，和稳定性的铝， 成年小鼠（Aim 2）。 这些研究将确定近端分子事件，可能与Sz风险遗传学相关， Sz Al中的小脊柱，以及脊柱形成/稳定受损的阶段。此类事件可能是 在未来的研究中通过CRISPR/Cas9在体内进一步研究，并有可能作为靶点。 开发新的治疗方法。

Abstract Schizophrenia (Sz) is a lifelong and devastating psychiatric illness with limited treatment options and no cure. Layer 3 pyramidal cell dendritic spine loss has been repeatedly observed in multiple brain areas in schizophrenia (Sz), including the primary auditory cortex (AI). Spine loss is postulated to underlie primary auditory cortex processing deficits observed in Sz, contributing to impaired social cognition and auditory hallucinations in Sz. We have shown that only smaller spines are lost in Sz Al layer 3. Recent two-photon in vivo imaging studies have shown that new spines are small, essential for synaptogenesis, and required for new learning in adult animals. Dendritic spine formation, stabilization, and plasticity are regulated by synaptic protein network (SynPN) features, such as protein expression, trafficking, and phosphorylation (Phos), and a significant number of Sz risk loci code for synaptic proteins. Targeted and shotgun mass spectrometry (MS) approaches found robust changes in synaptosome and Phos levels of canonical postsynaptic proteins in Sz. These changes were not explained by corresponding changes in homogenate levels of these proteins, suggesting that the brunt of SynPN pathology in Sz is regulated by processes beyond protein expression (e.g. protein trafficking and activity). Nine Phos sites on eight proteins were highly correlated with both synaptosome protein levels and small spine density. All but one of these 8 proteins have well documented roles in vesicular trafficking of postsynaptic glutamate receptors and spine regulation. Postsynaptic glutamate signaling is one of the most significantly implicated pathways in genetic studies of Sz. Thus, we hypothesize that: Aberrant trafficking and Phos of postsynaptic proteins is linked to Sz genetic risk and drives small spine loss in Sz Al. We will test this hypothesis in an unprecedented set of parallel genomic, proteomic, and microscopy experiments in 100 Sz and 100 matched control subjects with cutting edge computational analyses to identify protein and Phos linked to Sz genetics and generate causal models of disease (Aim 1). We will then utilize innovative molecular and two-photon microscopy approaches to test the effects of candidate Phos, from our preliminary studies and high priority Aim 1 findings, on spine density, size, formation, and stability in the Al of adult mice (Aim 2). These studies will identify proximal molecular events, potentially associated with Sz risk genetics, that impair small spines in Sz Al, as well as the stage of spine formation/stabilization that is impaired. Such events can be further investigated in vivo via CRISPR/Cas9 in future studies and have the potential to serve as targets for the development of novel therapeutics.