Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China.
Huashan Hospital, Fudan University, Shanghai, China.
Biol Psychiatry. 2023 Feb 1;93(3):279-290. doi: 10.1016/j.biopsych.2022.08.021. Epub 2022 Aug 31.
GABAergic (gamma-aminobutyric acidergic) interneurons (INs) are highly heterogeneous, and Htr3a labels a subpopulation of cortical INs originating from the embryonic caudal ganglionic eminence. SETDB1 is one of the histone H3K9 methyltransferases and plays an essential role in the excitatory neurons, but its role in regulating cortical inhibitory INs remains largely unknown.
In this study, we generated transgenic mice with conditional knockout of Setdb1 in neural progenitor cells (Setdb1-NS-cKO) and GABAergic neurons (Setdb1-Gad2-cKO). In addition, we performed RNA sequencing, ATAC-seq (assay for transposase-accessible chromatin with sequencing), chromatin immunoprecipitation sequencing, luciferase assay, chromatin conformation capture, and CRISPR (clustered regularly interspaced short palindromic repeats)/dCas9 to study the epigenetic mechanism underlying SETDB1-mediated transcriptional regulation of Htr3a. We also performed in situ hybridization and whole-cell recording to evaluate the functional properties of cortical Htr3a+ INs and behavioral tests for mood.
We detected significant upregulation of Htr3a expression in the embryonic ganglionic eminence of Setdb1-NS-cKO and identified the endogenous retroviral sequence RMER21B as a new target of SETDB1. RMER21B showed enhancer activity and formed distal chromatin interaction with the promoter of Htr3a. In addition, we observed an increased number and enhanced excitability of Htr3a+ INs in the knockout cortex. Moreover, Setdb1-Gad2-cKO mice exhibited anxiety- and depressive-like behaviors, which were partially reversed by a 5-HT receptor antagonist.
These findings suggest that SETDB1 represses Htr3a transcription via RMER21B-mediated distal chromatin interaction in the embryonic ganglionic eminence and regulates the development of cortical Htr3a+ INs and mood behaviors.
γ-氨基丁酸能（GABAergic）中间神经元（INs）高度异质，Htr3a 标记起源于胚胎尾侧神经节隆起的皮质 INs 的一个亚群。SETDB1 是组蛋白 H3K9 甲基转移酶之一，在兴奋性神经元中发挥着重要作用，但它在调节皮质抑制性 INs 中的作用在很大程度上仍是未知的。
在这项研究中，我们生成了条件性敲除神经前体细胞（Setdb1-NS-cKO）和 GABAergic 神经元（Setdb1-Gad2-cKO）中 Setdb1 的转基因小鼠。此外，我们进行了 RNA 测序、ATAC-seq（转座酶可及染色质测序）、染色质免疫沉淀测序、荧光素酶测定、染色质构象捕获和 CRISPR（成簇规律间隔短回文重复）/dCas9，以研究 SETDB1 介导的 Htr3a 转录调控的表观遗传机制。我们还进行了原位杂交和全细胞记录，以评估皮质 Htr3a+INs 的功能特性，并进行了情绪的行为测试。
我们在 Setdb1-NS-cKO 的胚胎神经节隆起中检测到 Htr3a 表达的显著上调，并鉴定出内源性逆转录病毒序列 RMER21B 是 SETDB1 的一个新靶点。RMER21B 表现出增强子活性，并与 Htr3a 的启动子形成远端染色质相互作用。此外，我们观察到敲除皮层中 Htr3a+INs 的数量增加和兴奋性增强。此外，Setdb1-Gad2-cKO 小鼠表现出焦虑和抑郁样行为，这些行为部分被 5-HT 受体拮抗剂逆转。
这些发现表明，SETDB1 通过 RMER21B 介导的胚胎神经节隆起中的远端染色质相互作用抑制 Htr3a 的转录，并调节皮质 Htr3a+INs 的发育和情绪行为。
