Microglia mediated suppression of dopamine induced neuronal responses and behavior

项目摘要 该提案的目的是确定支持小胶质细胞介导的抑制神经元凋亡的机制。 多巴胺反应小胶质细胞通过支持神经元存活来促进正常脑发育 以及脑组织清除无功能神经元和突触。我们发现了一种新的功能， 小胶质细胞，涉及抑制多巴胺诱导的行为在成年人的大脑。我们发现 对小胶质细胞进行全脑或纹状体特异性消融的小鼠显示出过度的多巴胺- 诱发运动活动和癫痫倾向这些发现表明， 小胶质细胞对纹状体神经元激活的影响。我们的初步数据表明，这种效应可能是由 直接通过多巴胺诱导的小胶质细胞激活。我们发现纹状体中10-15%的小胶质细胞 但在其他大脑区域不表达多巴胺D1受体。多巴胺D1的表达 纹状体小胶质细胞亚群的一种受体表明了一种潜在的新的负反馈 小胶质细胞在直接感知/响应多巴胺后调节神经元对多巴胺的反应的机制 神经递质水平的变化。我们的建议旨在阐明 小胶质细胞介导的多巴胺反应抑制，并围绕以下主要 问题：是否有一个特定的纹状体小胶质细胞亚群控制神经元抑制， 如果是，是否基于多巴胺直接触发小胶质细胞？小胶质细胞的抑制活性 针对特定的纹状体神经元亚群小胶质细胞产生的 影响神经元对多巴胺反应的介质我们的建议在很大程度上依赖于体内 动物模型，我们计划产生新的转基因小鼠品系，使操纵 纹状体中的小胶质细胞该提案的创新方法之一涉及到 在不同神经元和小胶质细胞群体中使用ART细胞类型特异性基因表达分析， 我们开发的技术，最大限度地减少细胞引起的基因表达的异常变化， 隔离程序。除了阐明特定的纹状体小胶质细胞和神经元亚群 我们的建议旨在确定小胶质细胞产生的调节因子， 多巴胺的神经反应我们发现小胶质细胞的抑制活性需要 含溴结构域蛋白Brd 4的表达，其作为基因表达的调节因子发挥作用。 转录。我们的数据表明，Brd 4结合的小胶质细胞基因，特别是那些被上调的基因， 可能编码多巴胺反应的小胶质细胞抑制因子。鉴定这些基因 是该提案的主要目标之一，我们计划通过使用小胶质细胞特异性RNA来实现， 我们开发的染色质分析。总的来说，我们的建议有可能识别新的小胶质细胞- 基于调节神经元对多巴胺反应的机制。

Project Summary The proposal's objective is to identify the mechanisms that support microglia-mediated suppression of dopamine responses. Microglia contribute to normal brain development by supporting neuronal survival and brain tissue clearance from non-functional neurons and synapses. We identified a novel function of microglia that involves the suppression of dopamine-induced behaviors in the adult brain. We found that mice with a pan-brain or striatum-specific ablation of microglia display exaggerated dopamine- induced motor activity and a propensity to seizures. These findings suggest a suppressive effect of microglia on striatal neuron activation. Our preliminary data suggest that this effect could be elicited directly by dopamine-induced microglia activation. We found that 10-15% of microglia in the striatum but not in other brain regions express the dopamine D1 receptor. The expression of the dopamine D1 receptor by a subpopulation of striatal microglia suggests a potential novel negative feedback mechanism where microglia tune neuronal response to dopamine after directly sensing/responding to changes in the neurotransmitter level. Our proposal aims to elucidate the mechanism underlying microglia-mediated suppression of dopamine responses and revolves around the following major questions: Is there a specific subpopulation of striatal microglia that controls neuronal suppression, and if yes, is it based on direct microglia triggering by dopamine? Does the suppressive activity of microglia target a specific subpopulation of striatal neurons? What is the nature of the microglia-produced mediators that impact neuronal responsiveness to dopamine? Our proposal relies heavily on in vivo animal models, and we plan to generate new strains of transgenic mice that enable the manipulation of microglia in the striatum. One of the innovative methodological aspects of the proposal involves state of the art cell type-specific gene expression analysis in different neurons and microglia populations using techniques developed by us that minimize aberrant changes in gene expression caused by cell isolation procedures. In addition to elucidating the specific striatal microglia and neuron subpopulations mediating the suppressive effect, our proposal aims to identify the microglia-produced regulators of neuronal responses to dopamine. We found that the suppressive activity of microglia requires the expression of the bromodomain-containing protein Brd4, which functions as a regulator of gene transcription. Our data suggest that Brd4-bound microglia genes, especially those that are upregulated by dopamine, may encode microglial suppressors of dopamine responses. Identification of these genes is one of the major goals of the proposal, which we plan to achieve by using microglia-specific RNA and chromatin analysis developed by us. Overall, our proposal has the potential to identify novel microglia- based mechanisms that regulate neuronal responses to dopamine.