Role of Gadd45b in Cocaine-driven Epigenetic and Behavioral Dynamics

精神刺激性药物滥用是一种公共健康危机，影响到美国数百万人和 造成严重的经济、社会和个人伤害。然而，尽管服药过量迅速增加 与可卡因等刺激性药物有关的死亡，目前仍没有批准的兴奋剂治疗方案 虐待障碍。精神刺激剂药物通过明确的信号机制作用于 伏核(NAC)中的多巴胺能神经传递，这是一种关键的奖赏相关脑结构， 整合来自不同大脑区域的信息，直接影响动机行为。此外，可卡因 导致NAC中棘神经元(MSN)的表观遗传和转录重组，促进 细胞信号和突触功能的不适应转变。我们的初步数据表明， Gadd45b(生长、停滞和DNA损伤诱导蛋白45b)在MSN中表达上调 可卡因和多巴胺受体的刺激，Gadd45b是可卡因相关记忆所必需的 队形。然而，尽管Gadd45b在表观遗传重新编程和记忆中起着关键作用 其他脑区的形成，Gadd45b在可卡因相关表观遗传学、分子和行为中的作用 适应情况尚不清楚。在这项提案中，我们将检验Gadd45b调节药物- 通过控制NAC中活性依赖的DNA去甲基化来诱导行为可塑性。的具体目标1 该方案将结合基于CRISPR的双向操作和单核RNA测序来 确定Gadd45b信号如何影响可卡因的转录反应。《特定目标2》将使用小说 Gadd45b工具和全基因组DNA甲基化分析，以确定调节 NAC中依赖Gadd45b的表观遗传编程。最后，特效靶标3将在体内使用细胞特异体 Gadd45b操作结合可卡因和自然奖励的行为分析来测试 假设Gadd45b增强可卡因的行为效应。总而言之，这些实验将确定 NAC中Gadd45b靶基因，剖析Gadd45b参与可卡因的表观遗传机制 表观遗传效应，并定义了Gadd45b在可卡因相关行为可塑性中的作用。这些研究将 揭示Gadd45b促进心理刺激反应的基本机制，并将为 为未来的实验探索滥用药物如何利用表观基因组来改变动机行为提供了方法。

Psychostimulant abuse is a public health crisis that affects millions of individuals in the United States and results in profound economic, social, and individual harm. However, despite rapid increases in overdose deaths linked to stimulant drugs like cocaine, there are still no approved therapeutic options for stimulant abuse disorders. Psychostimulant drugs act through well-defined signaling mechanisms to elevate dopaminergic neurotransmission in the nucleus accumbens (NAc), a key reward-linked brain structure that integrates information from diverse brain regions to directly influence motivated behavior. Further, cocaine causes epigenetic and transcriptional reorganization in medium spiny neurons (MSNs) in the NAc, promoting maladaptive shifts in cell signaling and synaptic function. Our preliminary data indicates that expression of Gadd45b (Growth, arrest, and DNA-damage inducible protein 45b) mRNA is upregulated in the MSNs after both cocaine and dopamine receptor stimulation, and that Gadd45b is required for cocaine-related memory formation. However, although Gadd45b plays a critical role in epigenetic reprogramming and memory formation in other brain regions, the role of Gadd45b in cocaine-related epigenetic, molecular, and behavioral adaptations is not clear. In this proposal, we will test the overarching hypothesis that Gadd45b regulates drug- induced behavioral plasticity by control of activity-dependent DNA demethylation in the NAc. Specific Aim 1 of this proposal will combine bidirectional CRISPR-based manipulations and single-nucleus RNA sequencing to determine how Gadd45b signaling impacts transcriptional responses to cocaine. Specific Aim 2 will use novel Gadd45b tools and genome-wide DNA methylation profiling to identify the molecular interactions that regulate Gadd45b-dependent epigenetic programming in the NAc. Finally, Specific Aim 3 will use cell-specific in vivo Gadd45b manipulations in combination with behavioral assays of cocaine and natural reward to test the hypothesis that Gadd45b enhances the behavioral effects of cocaine. Together, these experiments will identify Gadd45b target genes in the NAc, dissect epigenetic mechanisms by which Gadd45b contributes to cocaine’s epigenetic effects, and define a role for Gadd45b in cocaine-related behavioral plasticity. These studies will reveal fundamental mechanisms by which Gadd45b contributes to psychostimulant response, and will pave the way for future experiments to explore how drugs of abuse engage the epigenome to alter motivated behavior.