Epigenetic and transcriptional consequences of Intellectual Disability-associated mutations in the histone lysine demethylase KDM5.

摘要 智力残疾是一组以记忆困难为特征的神经发育障碍， 认知能力和适应能力。ID患者的全外显子组测序显示 编码KDM 5A、B和C的基因中的突变。1%到3%的X连锁ID（X-LID）归因于 高度神经元表达的Parkinson KDM 5C。KDM 5蛋白质最为人所知的是其酶促活性。 赖氨酸4上三甲基化的H3去甲基化（H3 K4 me 3），这是一种与 转录活性启动子。尽管Kdm 5c敲除小鼠显示出认知表型，但临床上没有发现 相关的途径已经确定，KDM 5调节转录的机制仍然是 不清楚果蝇有一个单一的，高度保守的KDM 5直系同源物，我们可以在其中模拟患者- 相关的ID突变，以了解它们对神经元发育的影响。我们实验室之前的一项研究 在果蝇中模拟ID突变揭示了核糖体蛋白基因（RPG）表达的减少， 蛋白质翻译，以及短期和长期记忆的缺陷。从头翻译对于记忆是必要的 形成，并发现在几种ID病症中改变。重要的是，修复翻译缺陷是一种 新兴的和潜在的治疗手段，以改善个人的认知功能与ID。 任何疗法的发展都缺乏对KDM 5如何在分子上发挥作用以调节细胞增殖的理解。 RP和其他基因的表达，这需要其典型组蛋白去甲基化酶活性的程度， 以及ID相关突变如何改变KDM 5功能。在这里，我们具体解决这些关键问题 通过评估启动子H3 K4 me 3水平系统地解码KDM 5在RPG表达中的作用， KDM 5相互作用组，以及这些如何被ID突变改变。

ABSTRACT Intellectual disabilities (ID) are a group of neurodevelopmental disorders characterized by difficulties in memory, cognition, and adaptive function by the age of 18. Whole exome sequencing from patients with ID reveals mutations in the genes encoding KDM5A, B, and C. One to three percent of X-linked ID (X-LID) is attributed to the highly neuronally expressed paralog KDM5C. KDM5 proteins are best known for their enzymatic demethylation of H3 that is tri-methylated on lysine 4 (H3K4me3), a chromatin modification associated with transcriptionally active promoters. Though Kdm5c knockout mice show cognitive phenotypes, no clinically relevant pathways have been identified and the mechanism by which KDM5 regulates transcription is still unclear. Drosophila possess a single, well conserved ortholog of KDM5 in which we can model patient- associated ID mutations to understand their effects on neuronal development. A previous study from our lab modeling ID mutations in Drosophila reveals a reduction in expression of ribosomal protein genes (RPG), total protein translation, and defects in both short and long-term memory. De novo translation is necessary for memory formation and is found to be altered in several ID disorders. Importantly, restoring translational defects are an emerging and potentially therapeutic means to improve the cognitive function of individuals with ID. Hindering the development of any therapies is a lack of understanding of how KDM5 functions molecularly to regulate the expression of RP and other genes, the extent to which this requires its canonical histone demethylase activity, and how KDM5 function is altered by ID-associated mutations. Here, we specifically address these key issues by systematically decoding the role of KDM5 in RPG expression by assessing promoter H3K4me3 levels, the KDM5 interactome, and how these are altered by ID mutations.