Role of histone acetyltransferases in memory storage and synaptic plasticity

项目摘要 组蛋白乙酰转移酶在记忆储存和突触可塑性中的作用 突触可塑性，即大脑中神经元连接强度的变化，被认为是记忆储存的基础，并可能在各种神经和精神疾病中发挥关键作用，包括阿尔茨海默病，精神发育迟滞，癫痫和抑郁症。突触可塑性的一种形式是长时程增强（LTP），这是一种活动依赖性的突触增强形式。与长期记忆存储一样，长期形式的LTP与短期增强不同，需要蛋白质合成和转录。蛋白激酶A（PKA）与其他激酶沿着激活转录因子如cAMP反应元件结合蛋白（CREB），导致基因诱导和长期记忆储存。然而，基因表达的调控不仅需要序列特异性转录因子如CREB，而且需要转录辅激活因子，如旁系同源因子CREB结合蛋白（CBP）和p300。CBP和p300是有效的组蛋白乙酰转移酶（HAT），通过修饰染色质结构以细胞类型和启动子特异性方式协调调节基因活性。记忆储存和突触可塑性的大部分工作都集中在CBP上。CBP突变和转基因显性阴性小鼠在空间学习和海马LTP范式中表现出缺陷。然而，对p300显性阴性转基因小鼠和p300条件性敲除的研究也显示了p300在空间记忆中的作用。一种常见的功能丧失遗传操作尚未用于研究CBP和p300，以剖析这些HAT在记忆存储中的需求。该项目旨在使用靶向方法，通过使用病毒载体，导致海马中CBP，p300或两者的空间限制性缺失。这种方法有两个目的：一个是有一个共同的操作，以评估不同的和重叠的作用的旁系同源物，另一个是确定的轨迹的行动，这些因素中的每一个是海马。该提案有三个目标：第一个是观察这些靶向缺失突变体的电生理学，特别是观察Schaffer侧支突触中cAMP依赖性、PKA依赖性和PKA非依赖性LTP模式。第二个目的是研究这些动物的行为表型，特别是在依赖于校园的任务中，如情境恐惧条件反射和空间物体识别。最后，第三个目标是在学习范例之前和之后，观察这些突变体中这些基因的靶基因表达和染色质乙酰化。这些研究将使我们能够比较这两种旁系同源HAT的不同和重叠的靶点，并有助于理解记忆储存过程中神经元中活性依赖的基因激活。

Project Summary The role of histone acetyltransferases in memory storage and synaptic plasticity Synaptic plasticity, the change in the strength of neuronal connections in the brain, is thought to underlie memory storage and may play a crucial role in a variety of neurological and mental disorders, including Alzheimer's disease, mental retardation, epilepsy and depression. One form of synaptic plasticity that has received much attention is long-term potentiation (LTP), an activity-dependent form of synaptic enhancement. Like long-term memory storage, long-lasting forms of LTP differ from short-term potentiation in requiring protein synthesis, and transcription. Protein kinase A (PKA) acts along with other kinases to activate transcription factors such as cAMP response element binding protein (CREB), leading to gene induction and long-term memory storage. The regulation of gene expression, however, requires not only sequence-specific transcription factors like CREB, but also transcriptional coactivators, such as the paralogous factors CREB- binding protein (CBP) and p300. CBP and p300 are potent histone acetyltransferases (HATs) that coordinately regulate gene activity in a cell type- and promoter-specific fashion by modifying chromatin structure. Much of the work in memory storage and synaptic plasticity has been focused on CBP. CBP mutant and transgenic dominant negative mice show deficits in spatial learning, and in hippocampal LTP paradigms. However, work on p300 dominant negative transgenic mice and p300 conditional knockouts also show a role for p300 in spatial memory. A common loss-of-function genetic manipulation has not been used to study both CBP and p300, in order to dissect the requirement of these HATs in memory storage. This project aims to use a targeted approach that would result in a spatially restricted deletion of CBP, p300 or both in the hippocampus, through the use of a viral vector. This approach serves two purposes: one is to have a common manipulation to assess the different and overlapping roles of the paralogues, and the other is to determine if the locus of action of each of these factors is the hippocampus. The proposal has three aims: the first is to look at the electrophysiology in these targeted deletion mutants; specifically looking at cAMP-, and PKA-dependent, and PKA-independent LTP paradigms in the Schaffer collateral synapse. The second aim is to look at the behavioral phenotypes of these animals, especially in hippocampus-dependent tasks such as contextual fear conditioning, and spatial object recognition. Finally, the third aim is to look at target gene expression and chromatin acetylation of these genes in these mutants, before and after a learning paradigm. These studies would allow us to compare the different and overlapping targets of these two paralogous HATs, and help in the understanding of activity-dependent gene activation in the neuron during memory storage.