The role of the DNA Methyltransferase1 (DNMT1) in the development of somatostatin (SST)-positive cortical interneurons

GABA能中间神经元的空间和时间抑制作用极大地影响了皮质信息处理，这反映在自闭症、癫痫和精神分裂症等涉及皮质抑制缺陷的疾病上。解密指导亚型特异性皮质间神经元发育的调控网络是非常有意义的，因为这有助于识别与此类疾病的病因学有关的关键事件。基因调控的表观遗传机制，如DNA甲基转移酶(DNMT)执行的DNA甲基化和组蛋白修饰，在塑造发育过程和人类健康方面受到越来越多的关注。几项研究将诊断为精神分裂症的患者胚胎和成人皮质间神经元亚群中DNA甲基转移酶1(DNMT1)的表达水平和功能改变联系起来。虽然越来越多的证据支持表观遗传信号与指导细胞类型特异性发育的相关性，但对于它们在离散发育过程和皮质神经元亚型特异性成熟中的功能暗示知之甚少。通过对FAC分类的胚胎中间神经元进行单细胞转录、整体转录组和甲基组分析，结合功能验证实验，我们最近发现DNMT1主要通过与组蛋白修饰的相互作用促进起源于视前区(POA)的中间神经元的迁移。相反，初步实验表明，DNMT1的DNA甲基化作用似乎对SST阳性中间神经元的正常发育至关重要，可能参与建立指导亚型特异性发育的转录程序。SST-中间神经元主要在MGE中产生，已被证明在精神分裂症和其他人类精神和神经疾病中受到影响。因此，我们在这里的目的是剖析DNMT1在SST阳性中间神经元有丝分裂后成熟中的作用。为此，我们将应用一系列创新和多样而又成熟的方法，包括小鼠遗传学、高通量测序和功能生物测定。为了确定DNMT1在SST-神经元间成熟过程中的调控过程，将对胚胎、出生后和成年条件DNMT1野生型和基因敲除小鼠进行全面的表型表征。此外，通过对富含FACS的SST中间神经元进行测序分析，以绘制DNMT1缺失时DNA甲基化和转录的全球变化图，将揭示迁移中SST中间神经元DNA甲基化依赖于DNMT1的重构。解码SST中间神经元在成熟过程中采用的依赖DNMT1的表观遗传重构有助于更好地理解亚型特异性发育程序，并可能与疾病相关问题相关，为建立基于表观遗传学的治疗开辟新途径。

The spatial and temporal inhibitory actions of the enormously heterogeneously collection of GABAergic interneurons tremendously influence cortical information processing, which is reflected by diseases like autism, epilepsy and schizophrenia that involve defective cortical inhibition. Decrypting regulatory networks that direct subtype-specific cortical interneuron development is of great interest, as this helps to identify critical events implicated in the etiology of such diseases. Epigenetic mechanisms of gene regulation like DNA methylation executed by DNA methyltransferases (DNMTs) and histone modifications call increasing attention in sculpting developmental processes and human health. Several studies associate altered expression levels and function of the DNA methyltransferase 1 (DNMT1) in subsets of embryonic and adult cortical interneurons in patients diagnosed with schizophrenia. Although accumulating evidence supports the relevance of epigenetic signatures for instructing cell type-specific development, only very little is known about their functional implications in discrete developmental processes and in subtype-specific maturation of cortical interneurons.By single cell transcriptomics, global transcriptome and methylome analysis of FAC-sorted embryonic interneurons in combination with functional validation experiments, we have recently found that DNMT1 promotes the migration of interneurons originating in the preoptic area (POA) mainly through interactions with histone modifications.In contrast, preliminary experiments indicate that DNA methylating actions of DNMT1 seem crucial for the proper development of SST-positive interneurons, potentially involved in setting up transcriptional programs that direct the subtype-specific development. SST-interneurons are generated mainly in the MGE and have been shown to be affected in schizophrenia and in other human psychiatric and neurological disorders. Thus, we here aim to dissect the role of DNMT1 in the post-mitotic maturation of SST-positive interneurons. To this end, we will apply an innovative and diverse yet well-established collection of methods involving mouse genetics, high-throughput sequencing and functional bioassays. To determine the processes DNMT1 regulates during SST-interneuron maturation, a comprehensive phenotypic characterization of embryonic, postnatal and adult conditional DNMT1 wild-type and knockout mice will be conducted. Moreover, DNMT1-dependent remodeling in DNA methylation in migrating SST-interneurons will be revealed by sequencing-based analysis of FACS-enriched SST interneurons to map the global changes in DNA methylation and transcription upon Dnmt1 deletion.Decoding the DNMT1-dependent epigenetic reconfigurations SST interneurons adopt during their maturation helps to better understand subtype-specific developmental programs and might be of relevance for disease-related questions, opening new avenues for the establishment of epigenetic-based therapies.