Biological Characterization of Genetic Mechanisms in Neuropsychiatric Disorders

神经精神疾病遗传机制的生物学特征

• 批准号: 7594625
• 负责人: Daniel Weinberger
• 金额: $ 75.45万
• 依托单位: NATIONAL INSTITUTE OF MENTAL HEALTH
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7594625
• 关键词: AKT1 gene; Accounting; Adult; Affect; Alleles; Animals; Antipsychotic Agents; Attention; Autopsy; Behavior; Biological; Biological Assay; Biology; Bipolar Disorder; Brain; Brain region; Catechols; Cell Differentiation process; Cell Line; Cell model; Cells; Chromosome Mapping; Clinical; Cognition; Cognitive; Collaborations; Complex; Coupling; DARPP 32; DISC1 protein; DLG4 gene; DNA; DNA biosynthesis; DRD2 gene; Data; Data Set; Development; Diagnosis; Disease; Dopamine; Emotional; Emotions; Environment; Equilibrium; ErbB4 gene; Europe; Event; Exons; FGF20 gene; Family; Functional disorder; Gene Expression; Generations; Genes; Genetic; Genetic Polymorphism; Genetic Variation; Genome; Genotype; Haplotypes; Hereditary Disease; Hippocampus (Brain); Human; Image; Incidence; Individual; Individual Differences; Institutes; Interview; Learning; Life; Link; Major Depressive Disorder; Malignant Neoplasms; Mammary Neoplasms; Mediating; Memory; Mental disorders; Methyltransferase; Mission; Modification; Molecular; Molecular Target; Motor Activity; Mus; Mutation; NRG1 gene; Neuregulin 1; Neurobiology; Neuroblastoma; Neurons; Neuropeptides; Neurosciences; Neurotransmitters; PLAB Protein; Pathogenesis; Pathway interactions; Patients; Pattern; Performance; Phenotype; Play; Prefrontal Cortex; Prevention; Process; Property; Protein Isoforms; Protein Overexpression; Proteins; Psychotic Disorders; RNA Splicing; Regulation; Relative (related person); Research; Research Personnel; Resources; Risk; Role; Schizophrenia; Scientist; Short-Term Memory; Signal Pathway; Signal Transduction; Site; Specificity; Staging; Stimulus; Stress; Structure; Susceptibility Gene; System; Testing; Therapeutic; Tissues; Transcript; Transcriptional Regulation; Translating; United States National Institutes of Health; Variant; Vision; Work; age group; base; brain morphology; case control; cell type; clinical Diagnosis; dopamine system; enzyme activity; fetal; gene environment interaction; gene function; gene interaction; genetic association; genetic variant; human FGF20 protein; mRNA Expression; memory recognition; methionylmethionine; migration; molecular pathology; neonate; neurobiological mechanism; neurogenesis; neuroimaging; neuropsychiatry; neuropsychological; neurotransmission; novel; pituitary adenylate cyclase activating polypeptide; postnatal; programs; promoter; protein expression; receptor; synaptogenesis; trait; tumorigenesis

Genes are major contributors to many psychiatric diseases, but their mechanisms of action have long seemed elusive. To date, we have evidence of association with schizophrenia in our family datasets of at least the following genes: COMT, DTNBP1, MUTED, EAA1, MRDS1, GAD1, DISC1, FEZ1, CITRON, NDE1, NRG1, PIK3d, ErbB4, DLG4, LIS1, MHTFR, DRD2, CAPON, PPP1R1B, DAARP, GRM3, CHRNA7, KCNH2, SREB2, PRODH, CAMKIIa, AKT1, FGF20, RELN1, and RCCX. Our dataset consists of individuals from over 750 families and case/control datasets of over 650. The unique aspects of our dataset, which may explain the strength of the genetic associations that have emerged, is that every subject, both cases and controls, are evaluated extensively with structured on sight interviews by the same clinicians who have worked together on this project for over ten years. As characterization of single genetic variants rapidly proceeds, research increasingly turns to dissecting gene-gene and gene-environment interactions. Our strategy for characterizing and mapping gene effects in brain with cognitive and neuroimaging assays enables us to better define intermediate phenotypes. Here we outline recent advances of linking genes to structural and functional variation in brain systems related to cognition and emotion. One study examined genotype effect of catechol-o-methyltransferase (COMT) Val158Met on corticolimbic circuitry and functional connectivity. We found that Met/Met subjects had the ability to focus attention on relevant stimuli while inhibiting interference from other stimuli. This may be of great advantage during working memory (WM) task, but may have deleterious effects in environments with multiple stimuli requiring rapid and flexible processing. Another study evaluated COMT and GRM3 and examined their combined effects on dissociable components of the WM network. We found an epistatic interaction of these genes on the engagement of prefrontal cortex. GRM3 genotype was associated with inefficiency and altered prefrontal coupling on the background of COMT Val. As we know, abnormalities in dopamine (DA) neurotransmission contribute to psychiatric disorders. It has been shown that a network of brain regions is involved in performance of declarative and recognition memory tasks and this network, hippocampus and VLPFC, is modulated by DA. Regulation of DA signaling and neurotransmission is critically affected by COMT. We examined the effect of COMT Val158Met on function and coupling during recognition memory. There is compelling evidence that DA is an important modulator of hippocampal and prefrontal cortical interaction. This suggests that individual differences in responsivity and connectivity related to genetic modulation of DA, is a mechanism accounting for some individual differences in recognition memory performance. We also examined the effects of the PACAP gene on neurobiological traits related to risk for schizophrenia (SCZ). PACAP is a neuropeptide with neurotransmission modulating activity. We found an allele is overexpressed in patients showing an association with reduced hippocampal volume and poorer memory performance. We generated mice lacking the PACAP gene and observed abnormal behaviors, like elevated locomotor activity, which were reversed by treatment with an antipsychotic. These data suggest that alterations in PACAP signaling may contribute to the pathogenesis of SCZ. Our examination of transcripts, protein processing and expression has resulted in several findings. One study of DA- and cAMP-regulated phosphoprotein (DARPP-32) we identified a common haplotype, which predicts mRNA expression in postmortem human brain. This haplotype is associated with enhanced performance on several cognitive tests and imaging revealed an impact on neostriatal volume, activation, and functional connectivity of PFC. We use postmortem brain to focus on postnatal developmental changes. We examined COMT enzyme activity and protein expression in the PFC in 6 age groups of normals. We found a significant increase in COMT enzyme activity from neonate to adulthood which is paralleled by increases in protein expression. COMT protein expression is related to the Val158Met genotype. These increases may reflect changes in the PFC dopamine system and stresses the importance of COMT for PFC dopamine regulation during maturation. We also examined the DISC1 gene. DISC1 is the result of a balanced molecular translocation, which segregates with major mental disorders like SCZ, bipolar disorder and major depressive disorder (MDD). Our association study of DISC1 with MDD and SCZ found the risk allele, Cys704 associated with increased risk of developing MDD. Ser704Cys variation impacts brain morphology in normals and in primary neuronal culture, knockdown of cellular DISC1 protein resulted in suppression of ERK and Akt modification, whose signaling pathways are implicated in MDD. A possible biological mechanism of MDD is associated with lower biological activity on ERK signaling. Many human genes are known to produce more than one protein isoform through various molecular events. The use of multiple DNA replication start sites (promoters) is a frequent mechanism for generation of isoforms that provide tissue/cell type specificity, developmental-stage specificity, and allows for diverse functional properties of a gene. Neuregulin 1 (Nrg1) has nine alternative promoters. Genetic variations in promoters can contribute to genetic diseases by creating entirely new transcripts from any given gene. Such mechanisms may underlie the pathogenesis of complex diseases like SCZ. Recently, altered expression of a novel isoform (type 4) in the brain has been associated with schizo-related genetic variants. We isolated and characterized NRG1 type 4 DNA from adult and fetal human brain and identified a novel splice variant. We found a NRG1 protein representing a putative type 4 proprotein which is exclusively expressed in adult and fetal brain. Nrg1 type 4 expression is higher in the fetal brain and may have an important functional role during early brain development mediated through NRG1s effects on neurogenesis, neuronal migration, cell differentiation and synapse formation, and the regulation of neurotransmitter function. The fact that expression is brain-specific may be valuable in terms of possible therapeutics of NRG1 type 4 in SCZ. Nrg1 plays an important role in oncogenesis, and is overexpressed in various cancer tissues. However, we did not detect NRG1 type 4 in breast tumor and neuroblastoma cell lines. This absence, when juxtaposed to increased NRG1 type 4 associated with risk for SCZ, may contribute to the reduced incidence of cancer in patients SCZ and their relatives. This convergent pattern suggests that genetic regulation of type 4 may have a dual effect of protecting against cancer while increasing risk for SCZ. We have shown that type 4 represents a novel, translated, developmentally regulated, brain-specific isoform. We also show that a NRG1 promoter mutation, which impacts risk, is functional and selectively affects transcriptional levels of the type 4 isoform, providing a mechanism for the functional associations. Lastly, recent identification of NRG1 receptor, ErbB4 as a candidate SCZ risk gene, suggests that other molecules in the NRG1 pathway may also be involved. It has been shown that a molecular mechanism contributing to the genetic association of NRG1 with SCZ involves altered transcriptional regulation of a novel variant of the gene. We examined ErbB4 splice variant gene expression in hippocampus and DLPFC. ErbB4 splice patterns remain unaltered in hippocampus of SCZ, however we show an increase in expression of only the splice variant containing exons 16 and 26 in DLPFC in SCZ, suggesting that an ErbB4 receptor with exons 16 and 26 domains is preferentially upregulated in the disea

基因是许多精神疾病的主要原因，但其作用机制长期以来似乎难以捉摸。迄今为止，我们的家庭数据集中至少有以下基因与精神分裂症相关的证据：COMT、DTNBP1、MUTED、EAA1、MRDS1、GAD1、DISC1、FEZ1、CITRON、NDE1、NRG1、PIK3d、ErbB4、DLG4、LIS1、MHTFR、DRD2、CAPON、PPP1R1B、DAARP、 GRM3、CHRNA7、KCNH2、SREB2、PRODH、CAMKIIa、AKT1、FGF20、RELN1 和 RCCX。我们的数据集由来自 750 多个家庭的个体和超过 650 个病例/对照数据集组成。我们数据集的独特之处在于，每个受试者（包括病例和对照）均由在该项目上合作了十多年的同一临床医生通过结构化的现场访谈进行了广泛的评估，这可以解释已出现的遗传关联的强度。随着单一遗传变异特征的快速进展，研究越来越多地转向剖析基因-基因和基因-环境相互作用。我们通过认知和神经影像分析来表征和绘制大脑中基因效应的策略使我们能够更好地定义中间表型。在这里，我们概述了将基因与认知和情感相关的大脑系统的结构和功能变异联系起来的最新进展。一项研究检查了儿茶酚邻位甲基转移酶 (COMT) Val158Met 的基因型对皮质边缘回路和功能连接的影响。我们发现 Met/Met 受试者能够将注意力集中在相关刺激上，同时抑制其他刺激的干扰。这在工作记忆（WM）任务中可能具有很大的优势，但在需要快速灵活处理的多种刺激的环境中可能会产生有害影响。另一项研究评估了 COMT 和 GRM3，并检查了它们对 WM 网络可分离成分的综合影响。我们发现这些基因在前额皮质的参与上存在上位相互作用。 GRM3 基因型与 COMT Val 背景下的低效率和前额叶耦合改变相关。众所周知，多巴胺（DA）神经传递异常会导致精神疾病。研究表明，大脑区域网络参与陈述性和识别性记忆任务的执行，并且该网络（海马体和 VLPFC）受到 DA 的调节。 DA 信号传导和神经传递的调节受到 COMT 的严重影响。我们研究了 COMT Val158Met 对识别记忆过程中功能和耦合的影响。有令人信服的证据表明 DA 是海马和前额皮质相互作用的重要调节剂。这表明与 DA 基因调节相关的反应性和连接性的个体差异是解释识别记忆表现中的一些个体差异的机制。我们还研究了 PACAP 基因对与精神分裂症 (SCZ) 风险相关的神经生物学特征的影响。 PACAP 是一种具有神经传递调节活性的神经肽。我们发现患者中的等位基因过度表达，与海马体积减小和记忆力较差有关。我们培育出缺乏 PACAP 基因的小鼠，并观察到异常行为，例如运动活动升高，但通过抗精神病药物治疗可以逆转这种行为。这些数据表明 PACAP 信号传导的改变可能有助于 SCZ 的发病机制。 我们对转录本、蛋白质加工和表达的检查得出了一些发现。在一项针对 DA 和 cAMP 调节的磷蛋白 (DARPP-32) 的研究中，我们发现了一种常见的单倍型，它可以预测死后人脑中的 mRNA 表达。这种单倍型与多项认知测试中表现的增强有关，成像显示对新纹状体体积、激活和 PFC 功能连接的影响。我们使用死后大脑来关注出生后的发育变化。我们检查了 6 个年龄组正常人 PFC 中 COMT 酶活性和蛋白表达。我们发现从新生儿到成年期 COMT 酶活性显着增加，同时蛋白质表达也增加。 COMT 蛋白表达与 Val158Met 基因型相关。这些增加可能反映了 PFC 多巴胺系统的变化，并强调了 COMT 对成熟过程中 PFC 多巴胺调节的重要性。我们还检查了 DISC1 基因。 DISC1 是平衡分子易位的结果，它与 SCZ、双相情感障碍和重度抑郁症 (MDD) 等主要精神疾病分离。我们对 DISC1 与 MDD 和 SCZ 的关联研究发现，风险等位基因 Cys704 与患 MDD 的风险增加相关。 Ser704Cys 变异影响正常人和原代神经元培养物中的大脑形态，细胞 DISC1 蛋白的敲低导致 ERK 和 Akt 修饰的抑制，其信号通路与 MDD 有关。 MDD 的一个可能的生物学机制与 ERK 信号传导的较低生物活性有关。 已知许多人类基因通过各种分子事件产生不止一种蛋白质亚型。使用多个 DNA 复制起始位点（启动子）是产生同种型的常见机制，这些同种型提供组织/细胞类型特异性、发育阶段特异性，并允许基因具有多种功能特性。神经调节蛋白 1 (Nrg1) 有九个替代启动子。启动子的遗传变异可以通过从任何给定基因创建全新的转录本而导致遗传疾病。这些机制可能是 SCZ 等复杂疾病发病机制的基础。最近，大脑中一种新型亚型（4 型）表达的改变与精神分裂症相关的遗传变异有关。我们从成人和胎儿大脑中分离并表征了 NRG1 4 型 DNA，并鉴定了一种新的剪接变体。我们发现了一种代表推定的 4 型前蛋白的 NRG1 蛋白，该蛋白仅在成人和胎儿大脑中表达。 Nrg1 4 型在胎儿大脑中表达较高，可能在早期大脑发育过程中通过 NRG1 对神经发生、神经元迁移、细胞分化和突触形成以及神经递质功能调节的影响而发挥重要的功能作用。就 SCZ 中 4 型 NRG1 的可能治疗而言，表达具有脑特异性这一事实可能很有价值。 Nrg1在肿瘤发生中发挥重要作用，并在多种癌组织中过表达。然而，我们没有在乳腺肿瘤和神经母细胞瘤细胞系中检测到 NRG1 4 型。这种缺失与与 SCZ 风险相关的 4 型 NRG1 增加并列，可能有助于降低 SCZ 患者及其亲属的癌症发病率。这种趋同模式表明，4 型基因调控可能具有预防癌症和增加 SCZ 风险的双重作用。我们已经证明，4 型代表一种新颖的、翻译的、发育调节的、大脑特异性的亚型。我们还表明，影响风险的 NRG1 启动子突变是有功能的，并且选择性地影响 4 型亚型的转录水平，从而为功能关联提供了机制。最后，最近将 NRG1 受体 ErbB4 鉴定为候选 SCZ 风险基因，表明 NRG1 途径中的其他分子也可能参与其中。研究表明，促成 NRG1 与 SCZ 遗传关联的分子机制涉及该基因新变体的转录调控的改变。我们检测了海马和 DLPFC 中 ErbB4 剪接变异体基因的表达。 ErbB4 剪接模式在 SCZ 的海马中保持不变，但是我们显示仅包含外显子 16 和 26 的剪接变体在 SCZ 的 DLPFC 中表达增加，表明具有外显子 16 和 26 结构域的 ErbB4 受体在该疾病中优先上调