Cell-type specific role of the circadian molecular clock in regulating hippocampal physiology and cognition

项目摘要 这项提议的首要目标是研究分子时钟的细胞特异性表达和作用。 在海马体内，对学习和记忆至关重要的大脑区域，受神经系统的影响 也存在昼夜节律紊乱的疾病，例如癫痫和神经退行性疾病。 昼夜节律是每24小时循环一次的生物过程，在许多生理学 在身体各处运作。在细胞水平上，昼夜节律是由一种 “时钟”基因的转录和翻译反馈环，称为分子时钟。这种分子 Clock在不同的组织和细胞类型中表达不同，并驱动许多其他基因的表达，从而 上升到昼夜节律影响的生理过程的多样性。因此，检查 分子时钟及其对组织和细胞特有的生理学的影响。 海马区依赖的记忆表现出昼夜节律，在记忆任务中表现最好 在夜间活动的啮齿动物中发生的。然而，海马体表达核心分子时钟组件， 在海马区，分子时钟的细胞特异性表达及其对细胞生理的影响 未知。这是复杂的海马体网络，由异质组成 神经元群体，每个群体都有不同的生理特性和基因表达谱。这项研究将 研究分子钟在两个海马神经元群体中的生理作用：兴奋性 锥体和小白蛋白(PV)中间神经元。第一，核心蛋白的内源性昼夜节律表达 时钟基因将在24小时内在这两个神经元群体中进行测量。接下来，分子钟的作用 在这两个神经元群体中，将评估其在调节海马区的生理和记忆方面的作用。至 做到这一点，时钟将被选择性地消融在兴奋性锥体细胞或PV中间神经元使用CRE/LOX 重组，然后是神经元的兴奋性，突触的可塑性，以及海马依赖的学习和 记忆将在白天和晚上进行评估。这一提议利用了单分子原位杂交， 全细胞和细胞外电生理学，以及海马区依赖的学习和记忆分析 确定分子钟在调节海马体生理和功能中的细胞特异性作用。 这一提议将对分子时钟的细胞特异性表达和功能产生新的见解 这可能会影响海马体的研究和疾病治疗策略。 鉴于许多神经疾病都有昼夜节律紊乱，理解分子和生理 整个大脑的节律对人类健康和疾病治疗至关重要，正如这一知识所能做到的 用于产生针对昼夜节律紊乱的治疗药物，并通知给药时间 现有的治疗方法。

Project Summary The overarching goal of this proposal is to investigate the cell-specific expression and role of the molecular clock within the hippocampus, a brain region critically important for learning and memory and affected by neurological disorders that also present with circadian rhythm disruptions, e.g. epilepsy and neurodegenerative diseases. Circadian rhythms are biological processes that cycle every 24 hours and are exhibited in many physiological functions throughout the body. At the cellular level, circadian rhythms are maintained by an oscillating transcriptional and translational feedback loop of ‘clock’ genes known as the molecular clock. This molecular clock is differentially expressed across tissue and cell-types and drives expression of many other genes, giving rise to the diversity of circadian-influenced physiological processes. Thus, it is important to examine the molecular clock and its impact on physiology in a tissue and cell-specific manner. Hippocampal-dependent memory exhibits circadian regulation, with peak performance on memory tasks occurring at night in nocturnal rodents. The hippocampus expresses core molecular clock components, however, the cell-specific expression of the molecular clock and its impact on cellular physiology in the hippocampus is unknown. This is complicated by the complexity of the hippocampal network, composed of heterogeneous neuronal populations, each with distinct physiological properties and gene expression profiles. This study will examine the physiological role of the molecular clock in two hippocampal neuron populations: excitatory pyramidal and parvalbumin-containing (PV) interneurons. First, the endogenous circadian expression of core clock genes will be measured over 24hrs in these two neuronal populations. Next, the role of the molecular clock within these two neuronal populations in regulating hippocampal physiology and memory will be assessed. To do this, the clock will be selectively ablated in either excitatory pyramidal cells or PV-interneurons using Cre/lox recombination and then neuronal excitability, synaptic plasticity, and hippocampal-dependent learning and memory will be assessed during the day and night. This proposal utilizes single-molecule in situ hybridization, whole-cell and extracellular electrophysiology, and hippocampal-dependent learning and memory assays to determine the cell-specific role of the molecular clock in regulating hippocampal physiology and function. This proposal will generate novel insight into the cell-specific expression and function of the molecular clock in the hippocampus and has the potential to impact research and disease treatment strategies in the hippocampus. Given that many neurological diseases have circadian disruptions, understanding molecular and physiological rhythms across the brain is critically important for human health and disease treatment, as this knowledge can be used to generate therapeutics targeting circadian disruptions and inform the timing of administration for existing therapeutics.