Genome-wide approaches reveal EGR1-controlled regulatory networks associated with neurodegeneration.

Early growth response gene 1 (Egr1) is a member of the immediate early gene (IEG) family of transcription factors and plays a role in memory formation. To identify EGR1 target genes in brain of Alzheimer's disease (AD) model mice - APP23, we applied chromatin immunoprecipitation (ChIP) followed by high-throughput DNA sequencing (ChIP-seq). Functional annotation of genes associated with EGR1 binding revealed a set of related networks including synaptic vesicle transport, clathrin-mediated endocytosis (CME), intracellular membrane fusion and transmission of signals elicited by Ca2+ influx. EGR1 binding is associated with significant enrichment of activating chromatin marks and appears enriched near genes that are up-regulated in the brains of APP23 mice. Among the putative EGR1 targets identified and validated in this study are genes related to synaptic plasticity and transport of proteins, such as Arc, Grin1, Syn2, Vamp2 and Stx6, and genes implicated in AD such as Picalm, Psen2 and App. We also demonstrate a potential regulatory link between EGR1 and its newly identified targets in vivo, since conditions that up-regulate Egr1 levels in brain, such as a spatial memory test, also lead to increased expression of the targets. On the other hand, protein levels of EGR1 and ARC, SYN2, STX6 and PICALM are significantly lower in the brain of adult APP mice than in age-matched wild type animals. The results of this study suggest that EGR1 regulates the expression of genes involved in CME, vesicular transport and synaptic transmission that may be critical for AD pathogenesis.

早期生长反应基因1（Egr1）是即刻早期基因（IEG）转录因子家族的成员，在记忆形成中起作用。为了在阿尔茨海默病（AD）模型小鼠APP23的大脑中鉴定EGR1的靶基因，我们应用了染色质免疫沉淀（ChIP）技术，随后进行高通量DNA测序（ChIP - seq）。与EGR1结合相关基因的功能注释揭示了一系列相关网络，包括突触小泡运输、网格蛋白介导的内吞作用（CME）、细胞内膜融合以及由钙离子内流引发的信号传递。EGR1结合与激活染色质标记的显著富集相关，并且在APP23小鼠大脑中上调的基因附近似乎富集。在本研究中鉴定和验证的假定EGR1靶标中，包括与突触可塑性和蛋白质运输相关的基因，如Arc、Grin1、Syn2、Vamp2和Stx6，以及与AD相关的基因，如Picalm、Psen2和App。我们还证明了EGR1与其新鉴定的体内靶标之间存在潜在的调控联系，因为在大脑中上调Egr1水平的条件，如空间记忆测试，也会导致靶标表达增加。另一方面，成年APP小鼠大脑中EGR1以及ARC、SYN2、STX6和PICALM的蛋白质水平明显低于年龄匹配的野生型动物。这项研究的结果表明，EGR1调节参与CME、囊泡运输和突触传递的基因的表达，这些过程可能对AD的发病机制至关重要。