Epigenetic Regulation of Serotonin:Relevance to HIV and Methamphetamine Abuse

了解HIV感染、甲基苯丙胺依赖和随后与抑郁、压力和下丘脑-垂体-肾上腺轴破坏相关的血清素系统变化之间的生物学机制，对于设计针对HIV感染和甲基苯丙胺成瘾的新的预防和治疗策略至关重要，这两种疾病都有很高的发病率。虽然编码5-羟色胺系统关键调节因子的基因的多态性变异，包括5-羟色胺转运蛋白（5-HTT）、单胺氧化酶A （MAOA）和色氨酸羟化酶2 （TPH2）已经被充分记录，但对这些基因的表观遗传调控知之甚少。表观遗传学被定义为在没有DNA序列改变的情况下发生的基因表达变化，已知通过对DNA、染色质和非编码rna的一系列分子修饰，有助于组织类型和发育阶段特定基因的表达。根据我们实验室产生的一系列证据，这项资助探索了一种假设，即TPH2的表观遗传调控，它编码脑5 -羟色胺合成中的限速酶，特别可能是HIV感染和甲基苯丙胺依赖导致5 -羟色胺系统变化的潜在机制，从而导致HPA轴功能改变、神经免疫失调、抑郁、临床治疗并发症，最终导致HIV感染的更高发病率。上瘾和死亡。我们最近证明TPH2 5'- utr含有一个反义启动子，在体外转录非编码RNA （Chen和Miller， 2009）。在Specific Aim 1中，我们将验证该转录本的存在，并评估其参与TPH2基因表达的调控。我们还将评估DNA甲基化和ccctc结合因子（CTCF）在TPH2基因表达调控中的作用。表观遗传机制涉及许多基因的时空表达，以及基因表达的环境调控。因此，Specific Aim 2将研究表观遗传修饰在5-羟色胺能基因、TPH2、5-HTT和MAOA的组织特异性和发育阶段表达中的作用，以及特定细胞因子和甲基苯丙胺对这些基因的潜在表观遗传调控。在Specific Aim 3中，我们将通过比较SIV+和SIV-恒河猴死后组织中血清素能基因的DNA甲基化，评估SIV感染和甲基苯丙胺对血清素能基因表观遗传修饰的影响。我们还将进行一项试点研究，以探索感染siv的恒河猴暴露于甲基苯丙胺是否会加剧血清素能基因的表观遗传修饰。我们预计，该项目的研究结果将有助于我们更好地理解潜在的生物学机制，制定新的策略来操纵5 -羟色胺神经传递，从而更好地治疗HIV和甲基苯丙胺相关的神经精神障碍，减少HIV在HIV阳性患者中的传播和死亡率，并加强对甲基苯丙胺成瘾和HIV合并症的治疗策略。了解艾滋病毒、甲基苯丙胺滥用和血清素系统变化之间的联系，对于设计新的预防和治疗艾滋病和甲基苯丙胺成瘾的策略至关重要，这两种疾病都有很高的发病率。本项目将研究5 -羟色胺神经传递的表观遗传调控及其与HIV和甲基苯丙胺滥用的相关性。我们期望这个项目产生的研究结果将为血清素系统的调节提供新的见解，并将导致治疗hiv感染和甲基苯丙胺成瘾及其合并症的新策略。

DESCRIPTION (provided by applicant): Project Summary Understanding the biological mechanisms that link HIV infection, methamphetamine dependence and consequent changes in the serotonin system that correlate to depression, stress and disruption of the hypothalamic-pituitary-adrenal axis is critical to designing new preventative and therapeutic strategies for both HIV infection and methamphetamine addiction, which have a high co-morbidity. While polymorphic variations in genes that encode the key modulators of the serotonin system, including the serotonin transporter (5-HTT), monoamine oxidase A (MAOA) and tryptophan hydroxylase 2 (TPH2) have been well-documented, epigenetic regulation of these genes is poorly understood. Epigenetics, which is defined as changes in gene expression that take place without a change in DNA sequence, is known to contribute to tissue-type and developmental stage specific gene expression, via an array of molecular modifications to both DNA and chromatin and non- coding RNAs. Borne out of a line of evidence generated in our lab, this grant explores the hypothesis that epigenetic regulation of TPH2, which codes for the rate limiting enzyme in brain serotonin synthesis, may in particular be an underlying mechanism by which HIV infection and METH dependence can cause changes in the serotonin system that lead to altered HPA axis function, neural-immune dysregulation, depression, complications for clinical treatment and ultimately, higher incidence of HIV infection, addiction and mortality. We have recently demonstrated that TPH2 5'-UTR harbors an antisense promoter, which transcribes a non- coding RNA in vitro (Chen and Miller, 2009). In Specific Aim 1, we will validate the existence of this transcript and assess its involvement in the regulation of TPH2 gene expression. We will also assess the involvement of DNA methylation and CCCTC-binding factor (CTCF) in the regulation of TPH2 gene expression. Epigenetic mechanisms are involved in spatiotemporal expression of numerous genes, as well as in environmental regulation of gene expression. Accordingly, Specific Aim 2 will investigate the role of epigenetic modification in the tissue-specific and developmental stage expression of the serotonergic genes, TPH2, 5-HTT and MAOA, as well as in the potential epigenetic regulation of those genes by specific cytokines and methamphetamine. In Specific Aim 3, we will assess the effect of SIV infection and methamphetamine on the epigenetic modification of the serotonergic genes, by comparing DNA methylation of serotonergic genes in postmortem tissues of SIV+ and SIV- rhesus monkeys. We will also perform a pilot study to explore whether methamphetamine exposure in SIV-infected rhesus monkeys exacerbates epigenetic modification of serotonergic genes. We anticipate that findings of this project will help us to better understand underlying biological mechanisms, develop new strategies to manipulate serotonin neurotransmission so as to treat HIV- and methamphetamine- associated neuropsychiatric disturbances better, reduce the spread of HIV and mortality among HIV+ patients, and enhance treatment strategies for methamphetamine addiction and HIV co-morbidity. PUBLIC HEALTH RELEVANCE: Project Narrative Understanding the link between HIV, methamphetamine abuse and changes in the serotonin system is critical to designing new preventative and therapeutic strategies for both AIDS and methamphetamine addiction, which have high co-morbidity. This project will investigate the epigenetic regulation of serotonin neurotransmission and its relevance to HIV and methamphetamine abuse. We anticipate that the research findings generated from this project will provide new insights into the regulation of the serotonin system and will lead to new strategies to treat HIV-infection and methamphetamine addiction and their co-morbidity.