Synaptic Dissection of Cell Adhesion Molecule Function within Subicular Circuits

毛细血管内细胞粘附分子功能的突触解剖

• 批准号: 8827859
• 负责人: Jason Aoto
• 金额: $ 9.27万
• 依托单位: STANFORD UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-04-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8827859
• 关键词: Acute; Adverse effects; Affect; Alternative Splicing; Animals; Behavior; Binding; Biological; Biological Assay; Brain; Cell Adhesion Molecules; Cells; Complex; Corpus striatum structure; DRD2 gene; Data; Development; Disease; Dissection; Dopamine; Dorsal; Economic Burden; Effectiveness; Electrophysiology (science); Family; Fiber; Functional disorder; Future; Gene Expression Profiling; Genome; Genomics; Goals; Grant; Health; Hippocampus (Brain); Human; Impaired cognition; Impulsivity; Individual; Infection; Injection of therapeutic agent; Interneurons; Investigation; Label; Ligands; Light; Link; Measures; Mediating; Mental Depression; Mental disorders; Mentors; Messenger RNA; Methods; Modeling; Molecular; Mus; Mutant Strains Mice; Mutation; Neurons; Nucleus Accumbens; Output; Patients; Phase; Play; Population; Probability; Property; Proteins; RNA Sequences; RNA Splicing; Recruitment Activity; Regulation; Relative (related person); Research; Rewards; Rhodopsin; Role; Schizophrenia; Shapes; Site; Slice; Specific qualifier value; Stress; Structure; Surface; Synapses; Synaptic Transmission; Synaptic plasticity; Techniques; Technology; Training; Virus; base; cell type; differential expression; dopamine system; hippocampal pyramidal neuron; in vivo; insight; mutant; neuropsychiatry; next generation; novel; novel therapeutics; optogenetics; postsynaptic; presynaptic; recombinase; research study; response; screening; small hairpin RNA; social; synaptic function; tool; transcriptome sequencing; transcriptomics; transmission process; treatment strategy; virus Cre recombinase

DESCRIPTION (provided by applicant): Increasing evidence suggests that abnormalities in synaptic transmission may be a key mechanism underlying some neuropsychiatric disorders. How might synaptic properties be specified an maintained? Synaptic cell adhesion molecules (SCAMs) are primary candidates that play a critical role regulating synapse function. Not surprisingly, genomic studies have found mutations in neurexin-3 (Nrx3) a prototypical presynaptic SCAM that is part of the neurexin/neuroligin complex. that are linked to Schizophrenia (SZ) and reward-seeking behavior. These disorders are associated with an enormous social and economic burden and share a common pathophysiological basis - dopamine system dysregulation due to abnormalities in synaptic transmission in the ventral subiculum (vSub) within the vSub-nucleus accumbens (NAc) shell circuit. Two distinct populations of subicular projection neurons serve as the major output of the hippocampus, receive input from CA1 and project to cortical and subcortical regions, including to two distinct medium spiny interneuron (MSN) cell- types in the NAc shell. A fundamental understanding how Nrx3 shapes cell-type specific synaptic properties at two subicular synapses involved in DA dysregulation - CA1 input to the vSub and subicular output to the NAc shell - is unexplored; thus, the dissection of cell-type specific pre- and post-synaptic functions of subicular neurons within this disease circuit may open new avenues for treatment strategies. To this end, we generated a Nrx3 mouse where splice site 4 (SS4), the splice site that dictates binding to nearly all neurexin ligands, is constitutively included (SS4+) but can be conditionally excluded (SS4-). We observed a selective reduction in AMPAR synaptic transmission, due to reduced surface AMPAR stability, in the dorsal subiculum of Nrx3SS4+ mice. Altered transsynaptic interactions in the Nrx3SS4 mouse may imitate disease-related Nrx3 mutations because most mutations affect surface exposed residues and alternative splicing - rarely resulting in complete protein loss. The overarching goal of this grant is to dissect presynaptic Nrx3SS4-dependent functions in distinct cell-types at the CA1-vSub synapse and the vSub-NAc shell synapse. The mentored aims will 1.) assess cell-type specific synaptic responses in vSub neurons that project to the NAc shell at the CA1-vSub synapse using stereotactic co-injection of retrograde virus and cre-recombinase in WT and Nrx3SS4 animals and 2.) assay vSub projections to two distinct populations of NAc shell MSNs in the striatal circuit by utilizing stereotactic injection of channelrhodopsin to selectively recruit ventral subicular fibers. For the R00 phase of this grant, will 1.) expand the study of synapse-specific striatal circuitry by dissecting the dorsal Sub-NAc core circuit using techniques acquired during the K99 phase and 2.) identify novel SCAMs by next-generation single-cell RNA sequencing of subicular neurons with the goal long-term of assessing their synaptic function in disease-relevant circuits. I anticipate that this proposal wil uncover new insights into cell-type specific synaptic properties in the subicular-striatal circuit and create a platform for future independent investigations into how other SCAMs function in subicular and striatal circuitry.

描述（由申请人提供）：越来越多的证据表明，突触传递异常可能是一些神经精神疾病的关键机制。突触特性如何被指定和维护？突触细胞粘附分子（SCAMs）是调节突触功能的主要候选者。毫不奇怪，基因组研究发现了neurexin-3（Nrx 3）的突变，这是一种典型的突触前SCAM，是neurexin/neuroligin复合物的一部分。与精神分裂症（SZ）和奖励寻求行为有关。这些疾病与巨大的社会和经济负担相关，并且共享共同的病理生理学基础-由于vSub-核内腹侧下托（vSub）的突触传递异常引起的多巴胺系统失调。两种不同的海马下托投射神经元群体充当海马的主要输出，从CA 1接收输入并投射到皮质和皮质下区域，包括NAc壳中的两种不同的中等多刺中间神经元（MSN）细胞类型。一个基本的理解如何Nrx 3形状的细胞类型特异性突触特性在两个subicular突触参与DA失调-CA 1输入的vSub和subicular输出的NAc壳-是未开发的，因此，解剖细胞类型特异性突触前和突触后功能的subicular神经元在这种疾病的电路可能打开新的途径的治疗策略。为此，我们产生了一种Nrx 3小鼠，其中剪接位点4（SS 4），即决定与几乎所有neurexin配体结合的剪接位点，被组成性地包括（SS 4+），但可以被有条件地排除（SS 4-）。我们观察到选择性减少AMPAR突触传递，由于减少表面AMPAR稳定性，在Nrx 3SS 4+小鼠的背侧下托。Nrx 3SS 4小鼠中改变的跨突触相互作用可能模仿疾病相关的Nrx 3突变，因为大多数突变影响表面暴露的残基和选择性剪接-很少导致完全蛋白质丢失。这项资助的首要目标是在CA 1-vSub突触和vSub-NAc壳突触的不同细胞类型中剖析突触前Nrx 3SS 4依赖性功能。指导的目标是1.）在WT和Nrx 3SS 4动物中使用逆行病毒和cre-重组酶的立体定向共注射评估投射到CA 1-vSub突触处的NAc壳的vSub神经元中的细胞类型特异性突触反应，和2.）通过利用视紫红质通道的立体定向注射来选择性地募集腹侧下托纤维，测定vSub投射到纹状体回路中NAc壳MSN的两个不同群体。对于R 00阶段的赠款，将1。通过使用在K99期获得的技术解剖背侧Sub-NAc核心回路来扩展突触特异性纹状体回路的研究; 2.）通过下一代下托神经元的单细胞RNA测序鉴定新型SCAMs，目标是长期评估其在疾病相关回路中的突触功能。我预计，这一建议将揭示新的见解，细胞类型特定的突触特性在下丘脑-纹状体电路，并创建一个平台，为未来的独立调查如何其他SCAMs功能在下丘脑和纹状体电路。