Transcriptional regulation of homeostatic and disease-associated-microglial genes by IRF1, LXRβ, and CEBPα
Transcriptional regulation of homeostatic and disease-associated-microglial genes by IRF1, LXRβ, and CEBPα
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DOI：
10.1002/glia.23678
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发表时间：
2019-07-13
期刊：
影响因子：
6.2
通讯作者：
Rangaraju, Srikant
中科院分区：
文献类型：
--
作者：
Gao, Tianwen;Jernigan, Janna;Rangaraju, Srikant
神经退行性变中小胶质细胞从稳态向疾病相关小胶质细胞（DAM）转变在DAM中，我们最近发现了不同的促炎和抗炎亚谱，尽管稳态和不同DAM谱的转录调节因子仍不清楚。根据这些研究，我们提出CEBP α、IRF1和LXR β可能是稳态、促炎和抗炎DAM状态的调节因子，并在初级小胶质细胞中进行体外siRNA研究，利用综合转录组学、生物信息学和实验验证方法，确定每种转录因子（TF）在调节小胶质细胞激活中的作用。小胶质细胞中TF的有效（>70%）沉默表明，在促炎激活后，每个TF之间特异性地相互调节。小胶质细胞的神经炎症转录组学分析与qPCR验证相结合，揭示了每个TF具有独特调节模式的不同基因簇，这些基因簇独立于LPS刺激。虽然所有三种tf（尤其是IRF1和LXR β）正向调节核心DAM基因（Apoe, Axl, cle7a， Tyrobp和Trem2）以及稳态和促炎DAM基因，LPS和IFN γ增加促炎DAM，但通过erk1 /2依赖性信号通路抑制稳态和抗炎DAM基因表达。IRF1和LXR β沉默抑制了聚苯乙烯微球和fA β 42的小胶质细胞吞噬活性，而IRF1沉默强烈抑制了促炎细胞因子的产生。我们的研究揭示了稳态和DAM谱的复杂转录调控，其中IRF1， LXR β和CEBP α积极调节促炎和抗炎DAM基因，而激活刺激独立地增强促炎DAM反应并通过Erk信号抑制稳态和抗炎反应。这一框架可以指导神经退行性疾病免疫调节治疗策略的发展。
Microglia transform from homeostatic to disease-associated-microglia (DAM) profiles in neurodegeneration. Within DAM, we recently identified distinct pro-inflammatory and anti-inflammatory sub-profiles although transcriptional regulators of homeostatic and distinct DAM profiles remain unclear. Informed by these studies, we nominated CEBP alpha, IRF1, and LXR beta as likely regulators of homeostatic, pro-inflammatory and anti-inflammatory DAM states and performed in-vitro siRNA studies in primary microglia to identify roles of each transcriptional factor (TF) in regulating microglial activation, using an integrated transcriptomics, bioinformatics and experimental validation approach. Efficient (>70%) silencing of TFs in microglia revealed reciprocal regulation between each TF specifically following pro-inflammatory activation. Neuroinflammatory transcriptomic profiling of microglia coupled with qPCR validation revealed distinct gene clusters with unique patterns of regulation by each TF, which were independent of LPS stimulation. While all three TFs (especially IRF1 and LXR beta) positively regulated core DAM genes (Apoe, Axl, Clec7a, Tyrobp, and Trem2) as well as homeostatic and pro-inflammatory DAM genes, LPS, and IFN gamma increased pro-inflammatory DAM but suppressed homeostatic and anti-inflammatory DAM gene expression via an Erk1/2-dependent signaling pathway. IRF1 and LXR beta silencing suppressed microglial phagocytic activity for polystyrene microspheres as well as fA beta 42 while IRF1 silencing strongly suppressed production of pro-inflammatory cytokines in response to LPS. Our studies reveal complex transcriptional regulation of homeostatic and DAM profiles whereby IRF1, LXR beta, and CEBP alpha positively regulate both pro- and anti-inflammatory DAM genes while activating stimuli independently augment pro-inflammatory DAM responses and suppress homeostatic and anti-inflammatory responses via Erk signaling. This framework can guide development of therapeutic immuno-modulatory strategies for neurodegeneration.