Decoding the RGS14 Interactome/Signalosome in CA2 hippocampal neurons

 描述（由申请人提供）：最近的高调报道已经确定了神秘的海马CA 2区是一个全新的海马回路的中心，这是与自闭症和精神分裂症相关的社会学习所必需的。与众所周知的三突触（齿状回（DG）-CA 3-CA 1）海马回路不同，对CA 2区知之甚少。以前，这一大脑区域与自闭症/双相障碍和精神分裂症的谱系有间接关系。然而，这些新的报告证明了CA 2在社会学习中的重要作用，在这个大脑区域与自闭症/双相情感障碍和精神分裂症之间提供了一个令人信服的新联系。因此，了解CA 2神经元中的信号蛋白和通路为开发新的治疗工具来治疗这些破坏性和令人烦恼的疾病提供了一个令人兴奋的新机会。 我们已经表明，脑蛋白RGS 14在成年小鼠和人类海马CA 2区的锥体神经元中表达。RGS 14是一种不寻常的支架/效应蛋白，其整合了G蛋白、MAP激酶和突触可塑性所必需的Ca++/CaM信号通路。我们最近发现RGS 14作为CA 2神经元而不是CA 1神经元中突触可塑性的天然抑制剂至关重要。缺乏RGS 14（RGS 14-KO）的小鼠在CA 2神经元中表现出显著的和意想不到的长时程增强（LTP），并且在基于海马的空间学习和记忆的获得中表现出显著的和意想不到的增强，在其他行为中没有差异。这些发现强调了理解RGS 14调节其天然宿主CA 2海马神经元突触可塑性的分子机制的重要性。迄今为止，对CA 2神经元中的信号蛋白/通路知之甚少。此外，我们对RGS 14信号传导功能的理解主要基于重组RGS 14和非天然表达系统中的伴侣的结合相互作用。基于这些发现，我们的工作假设是RGS 14是调节突触功能和可塑性所必需的信号通路的中心联系。然而，对于天然RGS 14的天然结合伴侣以及它在其天然宿主CA 2神经元内参与的信号传导途径，我们一无所知。与这一想法一致，我们的初步研究表明，天然RGS 14作为高分子量蛋白质复合物存在，并结合来自大脑的未识别的伴侣。这些研究的目标是确定新的信号通路在RGS 14表达CA 2海马神经元的未来研究，和具体的信号通路，天然RGS 14从事调节突触可塑性。目标1：使用生物信息学分析确定表达RGS 14的CA 2海马神经元的细胞转录组和蛋白质组以及CA 2特异性信号通路。目的2：鉴定来自脑的天然RGS 14的天然结合配偶体（野生型vs RGS 14-KO）。目标3：确定新鉴定的CA 2特异性受体通路在调节野生型和RGS 14-KO小鼠海马切片制备物的CA 2神经元中的LTP中的作用。

 DESCRIPTION (provided by applicant): Recent high profile reports have identified the enigmatic hippocampal area CA2 as being at the center of an entirely new hippocampal circuit that is essential for social learning linked to autism and schizophrenia. Unlike the well-understood trisynaptic (dentate gyrus (DG)-CA3-CA1) hippocampal circuit, very little is known about area CA2. Previously, this brain region had been indirectly implicated in the autism/bipolar spectrum of disorders and schizophrenia. However, these new reports demonstrating CA2's essential role in social learning provide a compelling novel link between this brain region with autism/bipolar disorders and schizophrenia. Therefore, understanding signaling proteins and pathways in CA2 neurons offers an exciting new opportunity for the development of novel therapeutic tools to treat these devastating and vexing diseases. We have shown that the brain protein RGS14 is expressed in pyramidal neurons of hippocampal region CA2 in adult mouse and humans. RGS14 is an unusual scaffold/effector protein that integrates G protein, MAPkinase, and Ca++/CaM signaling pathways essential for synaptic plasticity. We recently discovered that RGS14 is critically important as a natural suppressor of synaptic plasticity in CA2 neurons but not CA1. Mice lacking RGS14 (RGS14-KO) exhibit a marked and unexpected enhancement of long-term potentiation (LTP) in CA2 neurons and in the acquisition of hippocampal-based spatial learning and memory, with no differences in other behaviors. These findings highlight the importance of understanding the molecular mechanism(s) whereby RGS14 regulates synaptic plasticity in its natural host CA2 hippocampal neurons. To date, very little is known about signaling proteins/pathways in CA2 neurons. Furthermore, our understanding of RGS14 signaling functions is based largely on binding interactions of recombinant RGS14 and partners in non-native expression systems. Based on these findings, our working hypothesis is that RGS14 is a central nexus that regulates signaling pathways essential for synaptic function and plasticity. Yet nothing is known about natural binding partners of native RGS14, and the signaling pathways it engages within its natural host CA2 neurons. Consistent with this idea, our preliminary studies show that native RGS14 exists as a high molecular weight protein complex and binds unidentified partners from brain. The goal of these studies is to define novel signaling pathways in RGS14-expressing CA2 hippocampal neurons for future study, and the specific signaling pathways that native RGS14 engages to regulate synaptic plasticity. AIM 1: Determine the cell transcriptome and proteome of RGS14-expressing CA2 hippocampal neurons and CA2-specific signaling pathways using bioinfomatics analysis. AIM 2: Identify natural binding partners of native RGS14 from brain (wild type vs RGS14-KO). AIM 3: Determine roles for newly identified CA2-specific receptor pathways in regulating LTP in CA2 neurons of hippocampal slice preparations from wild type and RGS14-KO mice.