Epigenetic Regulation of Serotonin:Relevance to HIV and Methamphetamine Abuse

说明(申请人提供)：项目概要了解艾滋病毒感染、甲基苯丙胺依赖以及与抑郁、压力和下丘脑-垂体-肾上腺轴紊乱相关的5-羟色胺系统变化的生物学机制，对于为艾滋病毒感染和甲基苯丙胺成瘾设计新的预防和治疗策略至关重要，因为艾滋病毒感染和甲基苯丙胺成瘾的发病率很高。5-羟色胺系统的关键调节因子包括5-羟色胺转运体(5-HTT)、单胺氧化酶A(MAOA)和色氨酸羟基酶2(TPH2)等基因的编码基因的多态变异已被充分证实，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不改变DNA序列的情况下发生的基因表达的变化，已知通过对DNA和染色质以及非编码RNA的一系列分子修饰来促进组织类型和发育阶段特异性基因的表达。根据我们实验室产生的一系列证据，这笔赠款探索了一种假设，即对TPH2的表观遗传调控可能是HIV感染和冰毒依赖导致5-羟色胺系统改变的潜在机制，从而导致HPA轴功能改变、神经免疫失调、抑郁症、临床治疗的并发症，最终导致艾滋病毒感染、成瘾和死亡的更高发生率。我们最近证明了TPH25‘-UTR含有一个反义启动子，它在体外转录一个非编码的RNA(Chen和Miller，2009)。在特定的目标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，以及环境对基因表达的调控。因此，特定目标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。在具体目标3中，我们将通过比较SIV和SIV-恒河猴死后组织中5-羟色胺能基因的DNA甲基化，来评估SIV感染和甲基苯丙胺对5-羟色胺能基因表观遗传修饰的影响。我们还将进行一项初步研究，以探索感染SIV的恒河猴暴露于甲基苯丙胺是否会加剧5-羟色胺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了解潜在的生物学机制，开发新的策略来操纵5-羟色胺的神经传递，从而更好地治疗艾滋病毒和甲基苯丙胺相关的神经精神障碍，减少艾滋病毒在艾滋病毒患者中的传播和死亡率，并加强甲基苯丙胺成瘾和艾滋病毒共同发病的治疗策略。公共卫生相关性：项目说明了解艾滋病毒、甲基苯丙胺滥用和5-羟色胺系统变化之间的联系，对于为艾滋病和甲基苯丙胺成瘾设计新的预防和治疗战略至关重要，因为这两种疾病的发病率很高。该项目将调查5-羟色胺神经传递的表观遗传学调节及其与艾滋病毒和甲基苯丙胺滥用的相关性。我们预计，该项目产生的研究结果将为调节5-羟色胺系统提供新的见解，并将导致治疗艾滋病毒感染和甲基苯丙胺成瘾及其共同发病的新策略。

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.