Transcriptional control of microglia diversification and inflammation

项目摘要 我们的建议侧重于小胶质细胞介导的脑内稳态调节的表观遗传学机制 和神经退行性变。我们最近的研究揭示了大脑区域特定的小胶质细胞规格和 这表明这一规范与功能不同的大脑区域中不同的神经元表型相匹配。我们 表明区域小胶质细胞的指定取决于多梳抑制复合体2(PRC2)， 它以大脑区域特有的方式沉默小胶质细胞的基因。烧蚀PRC2“放宽”规范 伴随着神经功能和行为的退行性改变的小胶质细胞。这些发现 建议一个模型，在这个模型中，匹配的神经元和小胶质细胞之间的相互作用使小胶质细胞从 导致小胶质细胞介导的神经元损伤的因子的异常产生。为了检验我们的假设， 我们建议识别不同脑区小胶质细胞中的PRC2靶点，并确定 区域小胶质细胞规范的PRC2失活。PRC2已被证明在下游运行 不同的信号通路包括RAF/Erk信号通路，该信号通路已参与 小胶质细胞介导的神经毒性。我们假设这些信号通路的激活可能触发 控制小胶质细胞增殖、吞噬和/或促炎的基因异常表达 通过直接影响PRC2功能的活跃性。我们将解决信号诱导的小胶质细胞驱动之间的联系 神经毒性和PrC2介导的基因沉默。 神经变性过程中小胶质细胞介导的毒性很大程度上涉及炎症的激活。 回应。我们的建议旨在确定支持基因调控机制 小胶质细胞的促炎活性。我们发现BET蛋白，它连接组蛋白乙酰化和 RNA Pol II的激活在信号诱导的促炎基因转录中起关键作用 小胶质细胞。我们发现BET的药理抑制导致了对小胶质细胞的选择性抑制。 炎症基因在体外和体内的表达。BET家族包括结构不同的BRD2， BRD3和BRD4蛋白，均在小胶质细胞中表达。我们之前观察到了差异 巨噬细胞和神经元中单个BET蛋白与不同基因靶点的结合。将小鼠与 条件性小胶质细胞特异性失活，我们将确定单个BET蛋白对 健康大脑和神经退行性变过程中脑区特异性小胶质细胞表型。总而言之， 拟议的研究将确定区域特定小胶质细胞规范的新表观遗传机制。 以及这些机制对神经退化的贡献。控制DISTING的蛋白质鉴定 小胶质细胞的活动状态将有助于开发新的治疗方法来预防 和/或神经退行性变的减弱。

Project Summary Our proposal focuses on the epigenetic mechanisms of microglia-mediated regulation of brain homeostasis and neuro-degeneration. Our recent studies revealed brain region-specific microglia specification and suggested that this specification matches distinct neuron phenotypes in functionally distinct brain areas. We showed that regional microglia specification depends on the Polycomb Repressive Complex 2 (PRC2), which silences microglia genes in a brain-region specific fashion. Ablation of PRC2 “relaxes” specification of microglia followed by neurodegenerative-like changes in neuronal function and behavior. These findings suggest a model where interaction between “matching” neurons and microglia renders microglia from the aberrant production of factors responsible for microglial-mediated neuronal damage. To test our hypothesis, we propose to identify PRC2 targets in microglia in different brain regions and to determine the impact of PRC2 inactivation on regional microglia specification. PRC2 has been shown to operate downstream of different signaling pathways including the RAF/Erk signaling pathway, which has been implicated in microglia-mediated neurotoxicity. We hypothesize that activation of these signaling pathways may trigger the aberrant expression of genes controlling microglia proliferation, phagocytosis and/or proinflammatory activity by directly affecting PRC2 function. We will address the link between signal-induced microglia-driven neurotoxicity and PRC2-mediated gene silencing. Much of the microglia-mediated toxicity during neurodegeneration involves the activation of inflammatory responses. Our proposal aims at identification of the gene regulatory mechanisms supporting the proinflammatory activity of microglia. We found that BET proteins, which link histone acetylation and activation of RNA Pol II, play a key role in the signal-induced transcription of proinflammatory genes in microglia. We show that the pharmacological inhibition of BET leads to the selective suppression of microglia inflammatory gene expression in vitro and in vivo. The BET family includes the structurally different BRD2, BRD3 and BRD4 proteins, all of which are expressed in microglia. We previously observed differential binding of individual BET proteins to distinct gene targets in macrophages and neurons. Using mice with conditional microglia-specific inactivation, we will determine the contribution of individual BET proteins to brain region-specific microglia phenotypes in the healthy brain and during neurodegeneration. In summary, the proposed research will identify novel epigenetic mechanisms of region-specific microglia specification and the contribution of these mechanisms to neurodegeneration. Identification of proteins controlling distinct states of microglia activity will facilitate the development of novel therapeutic approaches for the prevention and/or attenuation of neurodegeneration.