Cross-Species Genetic and Epigenetic Studies of Stress Response and Reward

应激反应和奖励的跨物种遗传学和表观遗传学研究

• 批准号: 8344680
• 负责人: Christina Barr
• 金额: $ 122.88万
• 依托单位: NATIONAL INSTITUTE ON ALCOHOL ABUSE AND ALCOHOLISM
• 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/8344680
• 关键词: Affect; Affinity; Alcohol abuse; Alcohol consumption; Alcohol dependence; Alcoholism; Alcohols; Alleles; Animals; Anti-Anxiety Agents; Anxiety; Archives; Behavior; Behavioral; Binding; Brain; Brain region; Brain-Derived Neurotrophic Factor; Breeding; CRH gene; Candidate Disease Gene; Canis familiaris; Catarrhine; Cercopithecidae; Collaborations; DNA Modification Process; Data; Disease; Endorphins; Epigenetic Process; Euphoria; Evolution; Exhibits; Family; Frequencies; Gene Expression; Genes; Genetic; Genetic Polymorphism; Genetic Transcription; Genetic Variation; Genomics; Genotype; Glucocorticoid Receptor; Hippocampus (Brain); Home environment; Human; Human Genetics; Individual Differences; Ligand Binding Domain; Ligands; Link; Literature; Macaca; Macaca mulatta; Measures; Mental Depression; Mental disorders; Meta-Analysis; Mission; Modeling; Modification; Mood Disorders; Mus; NR3C1 gene; Names; National Institute on Alcohol Abuse and Alcoholism; Neuropeptides; Nicotine Dependence; Nucleic Acid Regulatory Sequences; Opioid; Oxytocin; Oxytocin Receptor; Peripheral; Phenotype; Pongidae; Post-Traumatic Stress Disorders; Primates; Process; RNA; Rat Strains; Rattus; Receptor Gene; Regulation; Reporting; Resistance; Rewards; Risk; Risk Factors; Rodent; Role; Sampling; Serine Protease; Site; Staging; Stress; System; Technology; Therapeutic Agents; Time; Tissues; Translating; Validation; Variant; addiction; alcohol related problem; alcohol use disorder; behavioral genomics; biological adaptation to stress; comparative; endogenous opioids; epigenomics; gain of function; gene environment interaction; genetic variant; histone modification; interest; life history; neurogenetics; next generation; nociceptin receptor; preference; promoter; receptor; response; serotonin transporter; social attachment; stress related disorder; stressor; trait

Neurogenetics of Reward Sensitivity We have been studying how spontaneous genetic variation that influences reward sensitivity, and which could be adaptive in certain contexts, may also increase risk for alcohol related problems. In both humans and rhesus macaques, there are polymorphisms in the mu-opioid receptor gene (OPRM1) that influence affinity of the receptor for its endogenous ligand, -Endorphin. We and others have shown that these polymorphisms predict increased alcohol-induced euphoria, suggesting them to have gain-of-function roles. Other, unrelated studies support this, in that HPA axis activity (which is restrained by endogenous opioids through this receptor) is decreased among human carriers of the alternative allele. We find this to be true in macaques as well and, moreover, find that this effect applies to a wide variety of stressors and extends across life history stages (Schwandt et al, 2011). We also have demonstrated it to relate to individual differences in response to natural rewards, as shown by measures of both reward bias in humans (Lee et al, in press) and social attachment in both human and macaque (Barr et al, 2008; Higham et al, 2011; Copeland et al, 2011). Another receptor in this family whose activity may influence reward system processing is the nociceptin receptor (OPRL1). Humans, rhesus macaques, and dogs all have missense variants at the c-terminal end of the receptor. These are present at high frequency, despite the fact that the region is under intense selection (high interspecific conservation and low intraspecific variation in dog and mouse). Whether variation at this gene influences alcohol consumption or other reward-dependent behaviors is currently under examination. Using Convergent Findings Across Species to Identify New Candidate Genes for Alcoholism Risk A variety of animal species have been used to model certain aspects of alcohol use and addiction. Strains of rats that have been selectively bred for alcohol preference have been enormously informative for identifying relevant intermediate phenotypes and for determining genetic contributions to alcohol consumption and related traits, and studies performed in macaques have repeatedly demonstrated their value for identifying genotype-phenotype relationships that translate to the human condition. In collaboration with LNG, we have performed a study that combines varied analytical approaches across species in order to home in on genes that may contribute to risk for alcohol use disorders in humans. RNA-Seq was performed in brain for two selectively bred lines of rats (P and NP) to identify differentially expressed genes. Among the 485 differentially expressed (FDR < 0.05) genes for the P and NP rat lines, the Fam111a gene showed an over twenty-fold difference between the P and NP lines. We then performed deep sequencing of the FAM111A gene in rhesus macaque, and identified 13 polymorphisms (SNPs), two of which were nonsynonymous and one of which was present in the proximal promoter. The promoter SNP was predicted to disrupt a number of important regulatory sites. The nonsynonymous SNPs did not significantly affect alcohol consumption, but animals carrying the promoter SNP exhibited alcohol consumption levels that were 2.5 times higher than those observed in animals homozygous for the ancestral allele. The FAM111a gene encodes a serine-endopeptidase, but little is known about its exact function. It has been shown that rats bred for a model of depression exhibit increased expression levels for FAM111A RNA in brain compared to resistant lines, and studies in humans show links between peripheral FAM111A expression levels and nicotine dependence. These data suggest that the FAM111A gene may contribute to risk for affective and addictive disorders in humans. Genomic and Epigenomic Studies Performed Using Next-Generation Sequencing In 2009, a high-profile meta-analysis was performed that called into the question the validity of many of the G x E findings that had been reported in the human literature. Debates surrounding this issue are ongoing, calling out for studies that might verify the validity of G x E interaction results by elucidating mechanisms by which they might occur. One mechanism by which stress could interact with genotype is via epigenetic modifications. The emergence of next generation sequencing technologies has broadened our potential for discovery of epigenetic effects. We have used these approaches and have been performing both ChIP- and MDP-Seq in order to examine effects of early stress on histone and DNA modifications in tissue derived from stress-sensitive brain regions (ie, hippocampus). Among the genes shown to be epigenetically regulated by stress in macaque were SLC6A4 (serotonin transporter), BDNF, CRH/CRHBP, NPY, and the glucocorticoid and oxytocin receptor genes (NR3C1 and OXTR), to name a few. The serotonin transporter finding was of great interest, since functional polymorphisms in the regulatory region for this gene have been shown to interact with early adversity in multiple primate species to predict vulnerability to stress-related problems (Barr, 2011; Schneider et al, 2011; Schwandt et al, 2011). The most robust result from this study was that obtained for the oxytocin receptor gene, OXTR. Results for OXTR held with four different analytical approaches, demonstrating stress-induced decreases in levels of both H3K4me3 binding and RNA expression levels in hippocampus. In order to provide functional validation for a role of epigenetic regulation at OXTR in G x E interactions, we then performed analyses to determine whether a non-synonymous SNP in the ligand-binding domain of OXTR would interact with early stress to influence relevant behavioral phenotypes. We found that in animals reared under conditions of early adversity, this genotype predicted increased levels of anxiety-like behavior and alcohol consumption. A larger sample is currently being genotyped in order to verify these effects. Oxytocin is a neuropeptide that produces affiliative, amnesic and anxiolytic affects. Given its roles in some of these processes, it has been proposed as a potential therapeutic agent for the treatment of anxiety and stress-related disorders, including PTSD. Functional variation that influences oxytocin system function may, therefore, be a particularly good candidate for performing gene x stress interaction studies in humans.

奖励灵敏度的神经遗传学 我们一直在研究如何影响奖励灵敏度的自发遗传变异，并且在某些情况下可能会适应性，也可能会增加与酒精相关的问题的风险。在人类和恒河猕猴中，MU-阿片受体基因（OPRM1）中都有多态性，会影响受体对其内源配体的亲和力 - 内源 - 内啡肽。我们和其他人表明，这些多态性预测酒精引起的欣快感增加，这表明它们具有功能障碍作用。其他无关的研究支持了这一点，因为HPA轴活动（通过该受体的内源性阿片类药物限制）在替代等位基因的人类载体中减少了。我们发现这在猕猴中也是如此，此外，发现这种效果适用于各种压力源，并在整个生活历史阶段延伸（Schwandt等，2011）。我们还证明了它与自然奖励的响应中的个体差异有关，如人类奖励偏见的衡量标准（Lee等人，印刷中）和人类和猕猴中的社会依恋（Barr等，2008; Higham et al，2011; Copeland et al，2011; Copeland et al，2011）所表明的。 该家族中可能影响奖励系统加工的另一个受体是诺西特蛋白受体（OPRL1）。人类，恒河猕猴和狗在受体的C末端都有错义变体。尽管该区域处于强烈的选择（狗和小鼠的种间保守性高，种间保守性较低，种内差异很低），这些事实仍处于高频。目前正在检查该基因的变异是否影响饮酒或其他依赖奖励依赖性行为。 使用跨物种的收敛发现来识别酗酒风险的新候选基因 各种动物物种已被用来建模酒精使用和成瘾的某些方面。为了鉴定相关的中间表型鉴定相关的中间表型，确定对酒精消耗和相关性状的遗传贡献，并且在猕猴中进行的研究已反复证明其价值以鉴定转化为人类状况的基因型 - 表现型关系，并且在猕猴中进行的研究已经反复证明了其对饮酒和相关性状的贡献。与LNG合作，我们进行了一项研究，该研究结合了各种物种的各种分析方法，以便以基因为家，这可能有助于人类患酒精饮酒障碍的风险。在大脑中对两条有选择性的大鼠（P和NP）进行RNA-SEQ，以鉴定差异表达的基因。在P和NP大鼠系的485个差异表达的基因（FDR <0.05）基因中，FAM111A基因在P和NP线之间显示出二十倍以上的差异。然后，我们在恒河猕猴中对FAM111A基因进行了深层测序，并确定了13种多态性（SNP），其中两个是非同义词，其中一个是近端启动子中存在的。预计启动子SNP会破坏许多重要的调节地点。非同义SNP并未显着影响饮酒，但是携带启动子SNP的动物表现出的饮酒水平是祖先等位基因纯合子中观察到的动物的2.5倍。 FAM111a基因编码丝氨酸 - 内肽酶，但对其确切功能知之甚少。已经表明，与耐药线相比，育种模型的大鼠培养大脑的表达水平升高，对人类的研究表明，对人类的研究表明，外周经FAM111a表达水平与尼古丁依赖性之间的联系。这些数据表明，FAM111A基因可能有助于人类患情感和成瘾性疾病的风险。 使用下一代测序进行的基因组和表观基因组研究 在2009年，进行了一项备受瞩目的荟萃分析，该分析召集了以下问题，这是人类文献中报道的许多G x E发现的有效性。围绕此问题的辩论正在进行中，呼吁进行研究，这些研究可能通过阐明可能发生的机制来验证G x e相互作用结果的有效性。压力可能与基因型相互作用的一种机制是通过表观遗传修饰。下一代测序技术的出现扩大了我们发现表观遗传作用的潜力。我们已经使用了这些方法，并且一直在执行芯片和MDP-seq，以检查早期应激对源自应激敏感大脑区域（IE，海马）组织中组蛋白和DNA修饰的影响。在猕猴中受到应激的表观遗传调节的基因中，有SLC6A4（5-羟色胺转运蛋白），BDNF，CRH/CRHBP，NPY，以及糖皮质激素和催产素受体基因（NR3C1和OXTR），仅举几例。血清素转运蛋白的发现引起了人们的极大兴趣，因为该基因的调节区域的功能多态性已被证明与多种灵长类动物物种的早期逆境相互作用，以预测与压力相关问题的脆弱性（Barr，2011; Schneider等，2011; Schwandt等，2011; Schwandt等，2011）。 这项研究最强大的结果是对于催产素受体基因Oxtr获得的结果。 OXTR采用四种不同的分析方法持有的结果，表明H3K4ME3结合水平和海马中RNA表达水平均降低。为了为在G x E相互作用中OXTR的表观遗传调节的作用提供功能验证，然后进行了分析，以确定OXTR的配体结合域中的非同义性SNP是否会与早期压力相互作用以影响相关行为表型。我们发现，在早期逆境条件下饲养的动物中，这种基因型预测了焦虑样行为和饮酒水平的增加。目前正在对较大的样本进行基因分型，以验证这些效果。催产素是一种神经肽，会产生从属，健忘和抗焦虑作用。鉴于其在其中一些过程中的作用，已被提议作为治疗焦虑和与压力有关的疾病（包括PTSD）的潜在治疗剂。因此，影响催产素系统功能的功能变异可能是对人类进行基因X胁迫相互作用研究的特别好的候选者。