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

描述（由申请人提供）：创伤后应激障碍（PTSD）是一种适应不良和使人衰弱的精神障碍，其特征是在创伤发生时极度恐惧，在创伤发生后的几个月和几年内出现特征性的再体验、逃避和过度觉醒症状。PTSD的患病率约为6%，但在经历过严重心理创伤的受试者中，如退伍军人、难民和袭击受害者中，可发生高达25%的PTSD。PTSD患者与非PTSD患者的差异风险是多重决定的：1)部分是遗传的，创伤后PTSD的遗传风险约为30-40%；2)与性别有关，女性在创伤后患PTSD的风险大约是男性的两倍；3)部分依赖于过去的个人历史，包括成人和童年创伤和心理因素，这些因素可能会对恐惧和情绪调节产生差异。垂体腺苷酸环化酶激活多肽（PACAP）先前已被确定为跨物种应激反应的关键调节因子。我们最近表明，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血液水平与女性恐惧生理、PTSD诊断和症状存在性别特异性关联（N=64，重复N=74, p<0.005）。使用标签-SNP遗传方法（44个单核苷酸多态性，SNP）跨越PACAP （ADCYAP1）和PAC1R （ADCYAP1R1）基因，我们发现单个SNP （rs2267735）与恐惧和创伤后应激障碍症状之间存在性别特异性关联。位于PAC1R中假定的雌激素反应元件（ERE）中的SNP可预测女性的恐惧反应、PTSD诊断和症状（初始和复制样本合并：N=1237; p<2x10-5）。该SNP的存在与PAC1R mRNA表达呈负相关，PAC1R甲基化与PTSD相关（p < 0.001）。与这些人类数据相补充，我们发现在啮齿动物模型中，恐惧条件或雌激素替代可诱导PAC1R mRNA表达。这些数据表明，PACAP/PAC1R通路的扰动与PTSD潜在的异常恐惧反应有关。本研究旨在通过更大的样本量来扩展这些初步发现，确定PACAP/PAC1通路活性的外周标志物作为PTSD的生物标志物。我们将进一步扩展这些数据，研究雌激素、PAC1R DNA甲基化/组蛋白乙酰化和PAC1R mRNA表达在创伤女性受试者PTSD症状和恐惧生理中的作用。我们将利用不同PAC1 rs2267735基因型的人淋巴母细胞系进一步研究PAC1调控的机制。

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.