Diurnal Experimental Models to Investigate Neural Mechanisms of Sleep Disturbance in Smith-Magenis Syndrome

摘要 睡眠问题是许多神经发育障碍中常见但未被充分认识的并发症。 值得注意的是，4个患有神经发育障碍的个体中有>1个表现出睡眠节律紊乱。这些 睡眠问题似乎加剧了不守规矩的行为，如侵略和自伤，使生活变得非常 这对患者及其家属来说很难。与此同时，许多单基因的致病基因 神经发育障碍编码转录和染色质调节因子。这些意见提出 关于睡眠障碍和神经发育状况之间关系的基本问题。 睡眠障碍是大脑发育受损的结果还是昼夜节律失调引起的 生物钟基因控制日常节律，包括睡眠/觉醒周期？与疾病相关的 转录调节因子直接控制神经发育基因，上游时钟基因， 或下游与睡眠有关的时钟靶基因？缺乏对这些问题的答案限制了基于证据的 睡眠节律和神经发育受损的治疗策略。 模式生物是建立基因在神经发育和睡眠中的因果作用的必然工具 人类遗传和临床关联之外的疾病。然而，实验室小鼠， 哺乳动物模型，是夜间的，即，在夜间活动，并倾向于在白天睡觉，而人类 都是白天的除了这种生理时钟类型的差异，大多数近交系小鼠不合成褪黑激素， 睡眠和神经发育关键调节剂。拟议项目旨在通过以下方式克服这些缺点 建立昼夜实验系统，探究睡眠障碍的遗传机制 与神经发育受损有关我们的目的基因是视黄酸诱导的1（RAI 1），其 杂合性导致Smith-Magenis综合征（SMS）。这种智力残疾综合症 包括白天嗜睡，夜间清醒，伴有血液倒置 褪黑激素周期多个实验室产生了Rai 1突变小鼠，但小鼠没有表现出睡眠节律 在SMS患者中观察到的干扰。RAI 1编码一种假定的组蛋白结合蛋白，与昼夜节律有关 时钟基因调控，但RAI 1的神经元昼夜节律基因调控的作用仍然未知。更好地 为了了解RAI 1的作用，我们将采用两种方法-尼罗河草鼠，一种昼行啮齿动物和人类 神经元来源于胚胎干细胞。拟议的研究将提供第一个昼夜实验 研究SMS病理生理学的系统和测试治疗干预的优秀平台 条件许多治疗剂已被证明在夜间啮齿动物模型中有效，但在人类中失败 临床试验，可能是由于生理时钟的差异。因此，迫切需要一个昼夜实验 系统，所提出的方法可以应用于其他神经发育障碍， 睡眠障碍及其他。

Abstract Sleep problem is a common but underappreciated comorbidity in many neurodevelopmental disorders. Remarkably, >1 in 4 individuals with neurodevelopmental disorders exhibit sleep rhythm disturbance. These sleep problems appear to exacerbate unruly behavior such as aggression and self-injury, making life very difficult for patients and their families. Meanwhile, numerous causative genes for monogenic neurodevelopmental disorders encode transcriptional and chromatin regulators. These observations raise fundamental questions about the relationship between sleep disturbance and neurodevelopmental conditions. Is sleep disturbance a consequence of impaired brain development or caused by dysregulation of circadian clock genes that controls daily rhythms, including the sleep/wake cycle? Do the disease-associated transcriptional regulators directly control the expression of neurodevelopmental genes, upstream clock genes, or downstream clock-target genes involved in sleep? Lack of answers to these questions limits evidence-based therapeutic strategies for impaired sleep rhythm and neurodevelopment. Model organisms are inevitable tools to establish causal roles of genes in neurodevelopment and sleep disturbance beyond genetic and clinical associations in humans. However, the laboratory mice, the primary mammalian model, are nocturnal, i.e., active during the night and tend to sleep during the day, while humans are diurnal. In addition to this chronotype difference, most inbred mouse strains do not synthesize melatonin, a key modulator of sleep and neurodevelopment. The proposed project aims to overcome these shortcomings by generating the diurnal experimental systems to interrogate the genetic mechanisms of sleep disturbance associated with impaired neurodevelopment. Our target gene is retinoic-acid induced 1 (RAI1), whose heterozygosity is responsible for Smith-Magenis Syndrome (SMS). This intellectual disability syndrome involves sleepiness during the day and elevated awakeness during the night, accompanied by inverted blood melatonin cycles. Multiple laboratories generated Rai1-mutant mice, but the mice did not exhibit sleep rhythm disturbance as seen in SMS patients. RAI1 encodes a putative histone-binding protein implicated in circadian clock gene regulation, yet the RAI1's role in neuronal circadian gene regulation remains unknown. To better understand the roles of RAI1, we will employ two approaches ― Nile grass rat, a diurnal rodent, and human neurons derived from embryonic stem cells. The proposed research will provide the first diurnal experimental systems to study SMS pathophysiology and excellent platforms to test therapeutic interventions for this condition. Numerous therapeutic agents have proven effective in nocturnal rodent models failed in human clinical trials, likely due to the chronotype difference. Thus, there is an urgent need for a diurnal experimental system, and the proposed approaches can be applied to other neurodevelopmental disorders that involve sleep disturbance and beyond.