Genome-Wide Identification of Basic Helix-Loop-Helix and NF-1 Motifs Underlying GR Binding Sites in Male Rat Hippocampus.
Genome-Wide Identification of Basic Helix-Loop-Helix and NF-1 Motifs Underlying GR Binding Sites in Male Rat Hippocampus.
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DOI：
10.1210/en.2016-1929
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发表时间：
2017-05-01
期刊：
影响因子：
4.8
通讯作者：
Conway-Campbell BL
中科院分区：
文献类型：
--
作者：
Pooley JR;Flynn BP;Grøntved L;Baek S;Guertin MJ;Kershaw YM;Birnie MT;Pellatt A;Rivers CA;Schiltz RL;Hager GL;Lightman SL;Conway-Campbell BL
糖皮质激素部分通过糖皮质激素受体（GR）调节基因表达来调节海马功能。GR结合是高度细胞类型特异性的，直接指向在组织分化过程中建立的可接近的染色质区域。不同种类的GR结合位点依赖于额外的信号激活转录因子的活性，这些转录因子将染色质引向上下文特异性组织。我们假设应激环境依赖于GR在海马中的结合，这是快速诱导应激介质启动染色质可及性的结果。使用染色质免疫沉淀测序来研究GR结合，我们发现约束应激环境对GR结合没有影响，尽管对GR结合位点的序列分析揭示了海马GR功能的机制细节。我们注意到与结构和组织作用相关的基因附近的GR结合位点丰富，GR缺乏主要的束缚伙伴，并且很少或没有证据表明与糖皮质激素负反应元件结合。一个基本的螺旋-环-螺旋基序与NeuroD1或Olig2结合位点非常相似，在GR结合位点的一个子集中被发现，并被提出作为指导GR海马染色质通路的候选谱系决定转录因子。在我们的GR结合位点中，54%额外含有核因子(NF)-1的半位点，我们认为核因子(NF)-1是参与海马GR功能的协同或一般转录因子。我们的研究结果表明，海马体中的GRs具有剂量依赖性和上下文无关性作用。NF-1/碱性螺旋-环-螺旋因子的表达或活性的改变可能通过改变GR进入海马结合位点，在糖皮质激素相关疾病的易感性和结局中发挥尚未确定的作用。与非应激对照相比，应激经历不影响海马体中的GR结合。GR结合机制包括通过基本螺旋-环-螺旋和NF-1基序的支持。
Glucocorticoids regulate hippocampal function in part by modulating gene expression through the glucocorticoid receptor (GR). GR binding is highly cell type specific, directed to accessible chromatin regions established during tissue differentiation. Distinct classes of GR binding sites are dependent on the activity of additional signal-activated transcription factors that prime chromatin toward context-specific organization. We hypothesized a stress context dependency for GR binding in hippocampus as a consequence of rapidly induced stress mediators priming chromatin accessibility. Using chromatin immunoprecipitation sequencing to interrogate GR binding, we found no effect of restraint stress context on GR binding, although analysis of sequences underlying GR binding sites revealed mechanistic detail for hippocampal GR function. We note enrichment of GR binding sites proximal to genes linked to structural and organizational roles, an absence of major tethering partners for GRs, and little or no evidence for binding at negative glucocorticoid response elements. A basic helix–loop–helix motif closely resembling a NeuroD1 or Olig2 binding site was found underlying a subset of GR binding sites and is proposed as a candidate lineage-determining transcription factor directing hippocampal chromatin access for GRs. Of our GR binding sites, 54% additionally contained half-sites for nuclear factor (NF)-1 that we propose as a collaborative or general transcription factor involved in hippocampal GR function. Our findings imply a dose-dependent and context-independent action of GRs in the hippocampus. Alterations in the expression or activity of NF-1/basic helix–loop–helix factors may play an as yet undetermined role in glucocorticoid-related disease susceptibility and outcome by altering GR access to hippocampal binding sites. A stressful experience does not influence GR binding in the hippocampus relative to nonstressed controls. Insights into GR binding mechanisms include support via basic helix–loop–helix and NF-1 motifs.