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脑出血的机制 多巴胺反应。小胶质细胞通过支持神经元存活促进正常脑发育 以及脑组织从无功能的神经元和突触中清除。我们确定了一种新的功能 小胶质细胞参与抑制成人大脑中的多巴胺诱导的行为。我们发现 对小胶质细胞进行泛脑或纹状体特异性消融的小鼠表现出夸大的多巴胺- 诱发的运动活动和癫痫发作的倾向。这些发现表明了一种抑制作用 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，这种效应是可以引起的。 直接通过多巴胺诱导的小胶质细胞激活。我们发现纹状体内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D_1的表达 纹状体小胶质细胞亚群的受体提示潜在的新的负反馈 小胶质细胞直接感觉/反应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背后的机制 小胶质细胞介导的多巴胺反应抑制，并围绕以下主要因素 问：是否有特定的纹状体小胶质细胞亚群控制神经元抑制，以及 如果是，它是基于多巴胺直接触发的小胶质细胞吗？小胶质细胞的抑制活性 以特定的纹状体神经元亚群为目标？小胶质细胞产生的性质是什么？ 影响神经元对多巴胺反应性的介质？我们的计划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，使其能够操纵 纹状体内的小胶质细胞。该提案的创新方法方面之一涉及国家 ART细胞类型特异性基因在不同神经元和小胶质细胞群体中的表达分析 我们开发的将细胞引起的基因表达异常变化降至最低的技术 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 通过调节抑制效应，我们的建议旨在确定小胶质细胞产生的调控因子 神经元对多巴胺的反应。我们发现，小胶质细胞的抑制活动需要 含溴结构域基因调控蛋白Brd4的表达 抄写。我们的数据表明，Brd4结合的小胶质细胞基因，特别是那些上调的基因 通过多巴胺，可能编码多巴胺反应的小胶质细胞抑制物。这些基因的鉴定 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和 染色质分析是我们自己开发的。总体而言，我们的提议有可能发现新的小胶质细胞- 以调节神经元对多巴胺反应的机制为基础。

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.