Genetic and estrogen-dependent regulation of the human PAC1R receptor and PTSD

描述(申请人提供)：创伤后应激障碍(PTSD)是一种适应不良和衰弱的精神障碍，其特征是在创伤发生时产生极端的恐惧感，在创伤后的几个月和几年内具有特征的重新体验、回避和过度觉醒的症状。创伤后应激障碍的患病率约为6%，但可发生在经历过严重心理创伤的受试者中，如退伍军人、难民和袭击受害者，比例高达25%。决定患有创伤后应激障碍的人与不患有创伤后应激障碍的人的风险差异是多方面的：1)部分是遗传因素，创伤后创伤后应激障碍的风险遗传率约为30%-40%；2)按比例取决于性别，女性在创伤后患创伤后应激障碍的风险约为男性的两倍；以及3)部分取决于过去的个人历史，包括成人和童年创伤以及可能以不同方式调节恐惧和情绪调节的心理因素。垂体腺苷环化酶激活多肽(PACAP)此前被认为是跨物种应激反应的关键调节因子。我们最近发现，PACAP及其PAC1受体(PAC1R)可能是心理创伤后异常过程的关键介质，例如人类的创伤后应激障碍(PTSD)。我们最近发现，在严重创伤的人类受试者中，PACAP的血液水平与女性的恐惧生理、创伤后应激障碍的诊断和症状存在性别特有的关联(N=，重复N=74，p&lt；0.005)。利用跨越PACAP(ADCYAP1)和PAC1R(ADCYAP1R1)基因的标签-SNP遗传方法(44个单核苷酸多态，SNPs)，我们发现单个SNP(Rs2267735)与恐惧和PTSD症状之间存在性别特异性的关联。SNP位于PAC1R中假定的雌激素反应元件(ERE)中，预测女性的恐惧反应、创伤后应激障碍诊断和症状(合并初始和复制样本：n=1237；p&lt；2x10-5)。这种SNP的存在与PAC1RmRNA的表达呈负相关，PAC1R的甲基化与创伤后应激障碍相关(p&lt；0.001)。补充这些人类数据，我们发现在啮齿动物模型中，恐惧条件或雌激素替代可以诱导PAC1R基因的表达。这些数据表明，PACAP/PAC1R通路的扰动参与了潜在的创伤后应激障碍的异常恐惧反应。这项建议旨在通过更大的样本量扩展这些初步发现，确定PACAP/PAC1通路活性的外围标记物作为PTSD的生物标记物。我们将通过研究雌激素、PAC1R DNA甲基化/组蛋白乙酰化和PAC1R mRNA表达在创伤后女性受试者的创伤后应激障碍症状和恐惧生理中的作用来进一步扩展这些数据。我们将用不同PAC1rs2267735基因型人淋巴母细胞系进一步研究PAC1的调节机制。 与公共健康相关：对恐惧及其抑制的神经回路有更机械性的理解是非常有必要的。我们最近利用趋同的遗传方法来确定PACAP/PAC1受体通路与创伤后应激障碍和人类条件性恐惧的失调有关。我们将通过检查雌激素、表观遗传调节和遗传多态对人类PAC1基因表达的不同调控机制来扩展这些数据。

DESCRIPTION (provided by applicant): Post-traumatic stress disorder (PTSD) is a maladaptive and debilitating psychiatric disorder characterized by an extreme sense of fear at the time of trauma occurrence, with characteristic re- experiencing, avoidance, and hyperarousal symptoms in the months and years following the trauma. PTSD has a prevalence of approximately 6%, but can occur in up to 25% of subjects who have experienced severe psychological trauma, such as combat veterans, refugees, and assault victims. The differential risk determining those who do vs. those who do not develop PTSD is multi-determined: 1) it is in part genetic, with approximately a 30-40% risk heritability for PTSD following trauma; 2) it in par depends on sex, with women having approximately twice the risk as men to develop PTSD following trauma; and 3) it in part depends on past personal history, including adult and childhood trauma and psychological factors which may differentially mediate fear and emotion regulation. Pituitary adenylate cyclase-activating polypeptide (PACAP) has previously been identified as a critical regulator of the stress response across species. We have recently shown that PACAP and its PAC1 receptor (PAC1R) may be critical mediators of abnormal processes following psychological trauma, such as with posttraumatic stress disorder (PTSD) in humans. We recently found, in heavily traumatized human subjects, a sex-specific association of PACAP blood levels with fear physiology, PTSD diagnosis and symptoms in females (N=64, replication N=74, p<0.005). Using a tag-SNP genetic approach (44 single nucleotide polymorphisms, SNPs) spanning the PACAP (ADCYAP1) and PAC1R (ADCYAP1R1) genes, we found a sex-specific association between a single SNP (rs2267735) and fear and PTSD symptoms. The SNP residing in a putative estrogen response element (ERE) within PAC1R, predicts fear response, PTSD diagnosis and symptoms in females (combined initial and replication samples: N=1237; p<2x10-5). The presence of this SNP is inversely correlated with PAC1R mRNA expression, and methylation of PAC1R is associated with PTSD (p < 0.001). Complementing these human data, we found that PAC1R mRNA is induced with fear conditioning or estrogen replacement in rodent models. These data suggest that perturbations in the PACAP/PAC1R pathway are involved in abnormal fear responses underlying PTSD. This proposal aims to extend these initial findings with a larger sample size, identifying peripheral markers of PACAP/PAC1 pathway activity as a biomarker for PTSD. We will further extend these data by examining the role of estrogen, PAC1R DNA methylation / histone acetylation, and PAC1R mRNA expression on PTSD symptoms and fear physiology in traumatized female subjects. We will further examine the mechanisms of PAC1 regulation using human lymphoblast cell lines of differing PAC1 rs2267735 genotypes. PUBLIC HEALTH RELEVANCE: There is a significant need for a more mechanistic understanding of the neural circuitry of fear and its inhibition. We have recently utilized convergent genetic approaches to identify the PACAP/PAC1 receptor pathway as being associated with PTSD and with dysregulation of conditioned fear in humans. We will extend these data by examining the mechanisms by which estrogen, epigenetic modulation, and genetic polymorphisms differentially modulate PAC1 gene expression in humans.