Early Brain Serotonin and Its Lasting Impact on Neuronal Epigenetic Programming

早期生命中的5-羟色胺信号影响神经发育轨迹，而改变的5-羟色胺信号 与许多与应激有关的精神疾病的发病机制有关。目前尚不清楚的是， 细胞外5-羟色胺对神经系统发育的影响以及关键的合成来源 5-羟色胺的主要成分是大脑。项目1：早期大脑5-羟色胺及其对神经元表观遗传学的持久影响 编程，Evan Deneris试图确定5-羟色胺是否专门在后脑中缝合成 神经元在胎儿和出生后早期的生命中分泌，是一种重要的细胞外信号，需要 5-羟色胺能动态平衡和下丘脑-垂体-肾上腺(HPA)的早期表观遗传程序 轴应力回路。为了研究这一假说，德内里斯试图应用他最近开发的临时性 受控靶向方法敲除负责合成的色氨酸羟基酶2基因 脑部5-羟色胺。TPH2将在胎儿和出生后早期用于减少大脑5-羟色胺的合成，但 不是从胎盘或肠道等外部来源合成5-羟色胺的。靶向TPH2的实验研究 早期生活的不同阶段使德内里斯能够调查一系列困难或 不可能用以前旨在确定大脑5的发育影响的方法来解决 羟色胺合成。在特定的目标1中，德内里斯将在胎儿生命和关键的出生后早期以TPH2为靶标 研究5-羟色胺作为维持体内平衡所需的自分泌信号的潜在作用的时期 内源性5-羟色胺神经元转录程序、内源性5-羟色胺神经元生化和生理学 属性和RNA编辑模式。在具体目标2中，德内里斯试图启动一项关于 以前未探索过的5-羟色胺能表观基因组，并确定它如何影响与压力相关的行为。TPH2 靶向小鼠将被用来确定早期5-羟色胺对组蛋白长期编程的影响 5-羟色胺能基因和5-羟色胺能基因的乙酰化/甲基化标记和DNA启动子甲基化模式 5-羟色胺能组蛋白脱乙酰酶(HDAC)的表达。HDAC2的5-羟色胺神经元型靶向 在发育中的5-羟色胺神经元中强烈表达，将被用来确定5-羟色胺能神经元如何改变 表观基因组影响5-羟色胺神经元功能和应激相关行为。在特定的目标3中，德内里斯的团队将 利用他强大的5-羟色胺神经元型遗传策略直接测试长期存在的假设 在大脑中产生的羟色胺是一种早期生活经验的发育转换器，需要 对HPA轴的发育进行表观遗传学规划，防止早期生活应激的影响。

Early life 5-HT signaling influences neurodevelopmental trajectories and altered 5-HT signaling has been implicated in the pathogenesis of numerous stress-related psychiatric disorders. What is not clear is how extracellular 5-HT exerts its effects on nervous system development and whether the critical synthetic source of 5-HT is the brain. In Project 1: Early Brain Serotonin and its Lasting Impact on Neuronal Epigenetic Programming, Evan Deneris seeks to determine whether 5-HT synthesized specifically in hindbrain raphe neurons and secreted during fetal and early postnatal life is an important extracellular signal required for early-life epigenetic programming of serotonergic homeostasis and hypothalamic-pituitary-adrenal (HPA) axis stress circuitry. To investigate this hypothesis, Deneris seeks to apply his recently developed temporally controlled targeting approaches to knock out the gene, tryptophan hydroxylase 2, responsible for synthesis of brain 5-HT. Tph2 will be targeted during fetal and early postnatal life to reduce brain 5-HT synthesis but not synthesis of 5-HT from exogenous sources such as the placental or gut. The targeting of Tph2 at different stages of early life enables Deneris to investigate a series of questions that have been difficult or impossible to address with previous approaches aimed at determining the developmental impact of brain 5 HT synthesis. In Specific Aim 1, Deneris will target Tph2 during fetal life and during the critical early postnatal period to investigate a potential role for 5-HT as an autocrine signal required for homeostatic maintenance of intrinsic 5-HT neuron transcriptional programs, intrinsic 5-HT neuron biochemical and physiological properties and RNA editing patterns. In Specific Aim 2, Deneris seeks to initiate a novel study of the previously unexplored serotonergic epigenome and determine how it impacts stress-related behaviors. Tph2 targeted mice will be used to determine the impact of early-life 5-HT on long lasting programming of histone acetylation/methylation marks and DNA promoter methylation patterns in serotonergic genes and serotonergic histone deacetylase (HDAC) expression. 5-HT neuron-type targeting of HDAC2, an HDAC strongly expressed in developing 5-HT neurons, will be used to determine how alterations in the serotonergic epigenome impacts 5-HT neuron function and stress-related behaviors. In Specific Aim 3, Deneris' team will utilize his powerful 5-HT neuron-type genetic strategies to directly test the long standing hypothesis that 5 HT produced in the brain is a developmental transducer of early life experience and is required to epigenetically program development of the HPA axis and protect against the effects of early life stress.