PSD-95 deficiency alters glutamatergic synapses during development in the prefrontal cortex

项目摘要/摘要 突触后密度蛋白-95(PSD-95)是一种高度丰富的支架蛋白，位于树突状细胞 兴奋性突触的脊椎，并参与N-甲基-D-D的招募、运输和稳定。 天冬氨酸受体(NMDAR)和α-amino-3-hydroxy-5-methyl-4-isox-azoleproprionic酸受体 (Ampar‘s)到突触成熟期间的突触后膜。此前的研究表明，在 在海马区，PSD-95缺乏会导致“无声突触”的形成，这可能与 精神分裂症(SCZ)和自闭症神经功能障碍的病理学观察然而，它的影响 前额叶皮质(PFC)中的PSD-95缺乏，这是一个大脑成熟延迟的区域，尚未出现 调查过了。PFC位于额叶的前部，负责认知、工作记忆、 情绪控制和社交能力。它还与神经发育障碍高度相关，尤其是 精神分裂症。我们假设PSD-95缺乏将扰乱年龄依赖性的突触成熟 NMDAR/AMPAR-谷氨酸能传递增加导致PFC损伤的方式 发展和功能。在这项研究中，我们使用PSD-95-/-小鼠来建立PSD-95缺陷的模型，并研究 内侧前额叶皮质(MPFC)内的NMDA和AMPA受体特性。我们探索蛋白质 NMDAR和AMPAR亚基及其他相关支架蛋白的表达水平。此外，我们 检查NMDAR/AMPAR的传递来表征沉默的突触，相应地，我们将检查 工作记忆功能和社交互动来衡量社会新颖性和探索性。此外，基于 在我们初步发现皮质传入细胞中NMDA/AMPA比率增加的基础上，我们将研究 Mpfc−的主要输入是丘脑内侧背侧，它负责发育和 通过谷氨酸能传递介导的相互联系发挥mPFC的功能。我们进一步 假设PSD-95缺乏将通过破坏谷氨酸能损害丘脑皮质投射 传递，导致突触功能和神经发育缺陷的传入特异性变化 导致生理和行为功能障碍的mPFC。我们将注射腺相关病毒(AAV) 在MD内表达通道视紫红质-2(ChR2)的载体，并利用光遗传学特异性激活MD MPFC的输入记录兴奋性突触后电流。总而言之，这些数据将提供更大的 理解PSD-95如何影响谷氨酸受体的组成和传递 MPFC的发展和功能。

Project Summary/Abstract Postsynaptic density protein-95 (PSD-95) is a highly abundant scaffolding protein located at the dendritic spines of excitatory synapses and is involved in the recruitment, trafficking, and stabilization of N-methyl-D- aspartic acid receptors (NMDAR’s) and α-amino-3-hydroxy-5-methyl-4-isox-azoleproprionic acid receptors (AMPAR's) to the postsynaptic membrane during synaptic maturation. Previous studies have shown that within the hippocampus, PSD-95 deficiency causes “silent synapse” formation that may be associated with the pathology observed in the neurological disorders of schizophrenia (SCZ) and autism. However, the effects of PSD-95 deficiency within the prefrontal cortex (PFC), a brain region with delayed maturation, have yet to be investigated. The PFC, located anterior of the frontal lobe, is responsible for cognition, working memory, emotional control, and sociability. It is also highly associated with neurodevelopmental disorders, especially schizophrenia. We hypothesize that PSD-95 deficiency will disrupt synaptic maturation in an age-dependent manner due to an increase in NMDAR/AMPAR-glutamatergic transmission that leads to impairments in PFC development and function. In this study we use a PSD-95-/- mouse to model PSD-95 deficiency and investigate NMDA and AMPA-receptor properties within the medial prefrontal cortex (mPFC). We explore protein expression levels of NMDAR and AMPAR-subunits and other relevant scaffolding proteins. Additionally, we examine NMDAR/AMPAR-transmission to characterize silent synapses, and accordingly, we will examine working memory function and social interaction to measure social novelty and exploration. Furthermore, based on our preliminary finding of increased NMDA/AMPA ratio in corticocortical afferents, we will examine the major inputs of the mPFC − the mediodorsal thalamus (MD), which is responsible for the development and function of the mPFC via reciprocal connections mediated by glutamatergic transmission. We further hypothesize that PSD-95 deficiency will impair thalamocortical projections via disrupted glutamatergic transmission, resulting in afferent-specific changes in synaptic function and neurodevelopmental deficits of the mPFC that lead to physiological and behavioral dysfunctions. We will inject an adeno-associated virus (AAV) vector expressing channelrhodopsin-2 (ChR2) within the MD and use optogenetics to specifically activate MD inputs to mPFC to record excitatory postsynaptic currents. Together, this data will provide a greater understanding of how PSD-95 affects the glutamate receptor composition and transmission as it relates to mPFC development and function.