Temporal dynamics of Arc (Arg3.1) transcriptional regulation

摘要： 学习和记忆障碍是几种精神疾病的特征，包括 精神分裂症、自闭症和阿尔茨海默氏症。这些认知过程在正常和疾病中都存在 状态是由神经元回路中时空调节的基因控制的。研究表明， 涉及即刻早期基因(IEGs)的作用，特别是活性调节的细胞骨架 与行为反应相关(Arc/Arg3.1)。ARC引起了人们的特别兴趣，因为它 影响突触传递、可塑性和长期记忆。从短期的转换 对于长期记忆，一个被称为巩固的过程，需要Arc蛋白水平 维持几个小时到几天。然而，现有的研究表明，药物的半衰期很短。 Arc mRNA和蛋白(小于60min)。耐人寻味的是弧形的时间窗有多短 表达能在很长时间内促进记忆的巩固。对于包括Arc在内的IEG， 基因表达调控始于转录水平。因此，我们假设 神经元子集中的周期性转录循环将使Arc水平在 用于稳定内存跟踪的网络。我们建议确定分子机制。 在这些转录循环的背后。最近，我们制作了一种敲入小鼠模型 在内源性Arc基因用噬菌体衍生的茎环荧光标记的情况下， 在单个神经元中实现高检测灵敏度和单个Arc等位基因的成像 几个小时以前所未有的时间分辨率。通过内生弧的实时成像 在培养的神经元和急性海马片中的基因转录，我们将建立长时间的 Term Arc转录动力学及其对神经元活动模式的依赖。我们会 描述活动和翻译反馈在Arc转录调控中的作用 不同的时间尺度。这将提供对以下方面的见解：i)Arc转录调控多长时间 影响记忆整合和ii)改进以活动为基础的报告器设计，以可靠地 关联Arc表达和行为。

Abstract: Deficits in learning and memory are hallmarks of several psychiatric disorders including schizophrenia, autism, and Alzheimer’s. These cognitive processes in both normal and disease states are controlled by spatiotemporally regulated genes in neuronal circuits. Studies have implicated the role of immediate-early genes (IEGs), particularly, Activity-regulated cytoskeletal associated (Arc/Arg3.1) in behavioral responses. Arc has garnered special interest because it affects synaptic transmission, plasticity and long-term memory. The conversion from short-term to long-term memory, a process known as consolidation, requires Arc protein levels to be maintained over several hours to days. However, existing studies indicate very short half-lives of Arc mRNA and protein (less than 60 mins). It is intriguing how short temporal window of Arc expression promotes memory consolidation over long time scales. For IEGs including Arc, the regulation of gene expression initiates at the level of transcription. Therefore, we hypothesize that periodic cycles of transcription in a subset of neurons would enable persistence of Arc levels in the network for stabilizing the memory trace. We propose to identify the molecular mechanisms underlying these transcription cycles. Recently, we have generated a knock-in mouse model where the endogenous Arc gene is fluorescently labeled with bacteriophage-derived stem loops, enabling high detection sensitivity and imaging of individual Arc alleles in single neurons over several hours with unprecedented temporal resolution. By real-time imaging of endogenous Arc gene transcription in cultured neurons and in acute hippocampal slices, we will establish the long- term Arc transcription dynamics and its dependence on patterns of neuronal activity. We will characterize the role of activity and translational feedback in Arc transcriptional regulation at different time scales. This will provide insights into: i) how long term Arc transcriptional regulation impacts memory consolidation and ii) improve design of activity-based reporters to reliably correlate Arc expression and behavior.