KDM5蛋白维持肠道微生态平衡的功能及其机制研究

Gut microbiome regulates a variety of animal physiology, behavior and metabolic activity. Intestinal microbiome disturbance is related to the development and progression of many diseases. KDM5 family proteins are important transcriptional regulators that activate or repress gene expression in a context-dependent manner. Dysregulation of KDM5 proteins in humans results in intellectual disability (ID) diseases, autism and cancer. Mutations in KDM5A and KDM5C are found in patients with autosomal recessive intellectual disability. Imbalance of gut microbial populations or dysbiosis is implicated in the intellectual disability and autism diseases. However, the genetics mechanisms of gut dysbiosis in these diseases are unclear. Using Drosophila as model, we indentified phylogenetic differences in gut microbiome in wildetype and KDM5-/- mutant flies and found KDM5-/- intestinal epithelial showed disrupted stucture. Based on the KDM5 protein importance in diseases, in the current proposal, we will use Crisper-cas9 technique to build conserved mutant site of fly. Futhermore, we will take advantge of these screening mutant flies to investigate the function and machanism of KDM5 protein in the maintance of normal gut micrbiota, the relationship between dysbiosis and brain behavior. We believe that the research would provide an important theoretical basis for the pathogenesis of diseases caused by pathogens, and exploit to develop novel strategies to treat or prevent ID diseases by restoring KDM5 function and healthy microbe–host interactions.

肠道微生态紊乱与多种疾病的发生发展过程密切相关。近年来，很多参与到调节肠道微生态过程中的重要宿主蛋白被发现。KDM5家族蛋白是重要的激活或抑制基因表达的染色体蛋白，参与了多种生物学过程的调控。该蛋白的失调与人类癌症发生，神经系统的智能和认知障碍密切相关，然而在肠道免疫方面的功能还未见报道。我们在前期研究中发现，KDM5蛋白功能失活的突变体果蝇肠道菌群紊乱，肠上皮细胞不能正常增殖分化。临床研究表明智能障碍和自闭症患者肠道免疫异常，菌群失调。并且该类患者KDM5蛋白家族频繁出现基因突变情况。因此本项目将在此基础上，利用CRISPR-Cas9技术构建与病人突变位点保守的突变体果蝇，采用高通量测序技术，无菌和感染动物模型以及行为分析等分子生物学技术揭示KDM5蛋白在肠道微生态的作用机理和功能，从而为由病原体引起的疾病发病机理提供重要的理论基础，也为人类治疗该疾病提供研究基础，防治和治疗依据。

KDM5家族蛋白是一类去组蛋白甲基化酶，它参与基因的表观遗传调控过程。此前有研究表明，在智力障碍以及孤独症患者中，存在KDM5家族蛋白（KDM5A/KDM5B/KDM5C）的基因突变以及功能的丧失。在本研究中，我们已模式生物果蝇为模型探讨KDM5如何调控ID和ASD发生发展的。研究发现KDM5功能丧失会导致肠屏障功能受损和与肠道微生态失调，同时出现社交行为异常的现象。 通过给予抗生素或益生菌（植物乳杆菌L168）能够部分挽救因KDM5蛋白功能缺失而导致的果蝇的社交行为紊乱、寿命缩短、以及细胞表型产生的变化。从分子层面，本研究发现KDM5通过其去甲基化酶的活性，能够调节“免疫缺陷信号通路（immune deficiency signaling，IMD）”组成基因的表达，从而影响了体内共生菌的稳态平衡。肠道菌群结构的紊乱则影响了神经递质5-HT的代谢，从而影响了个体的社会性行为。本研究详细解读和分析了KDM5在肠道-微生物群-大脑轴中的作用和机制，这项研究成果将拓展人们对孤独症诱发因素的认识，也为孤独症的诊疗提供了新的线索。