Chemokine Receptor Function in the Nervous System

描述（由申请人提供）：在我们最初的提议中，我们试图证明成人脑中神经祖细胞表达趋化因子受体，以检查SDF 1/CXCR 4信号传导对齿状回（DG）中成人神经祖细胞的影响，并研究HIV 1对该过程的影响。我们成功地实施了这些项目。事实上，这种情况已经发展到这样一种程度，以至于从我们的工作中自然产生了几个新的具体目标。 一个重要的成就是开发了几种不同品系的双色BAC转基因小鼠，这些小鼠报告了趋化因子（SDF 1，MCP 1-RED）及其受体（CXCR 4，CCR 2-绿色）的表达。这些小鼠使我们能够证明SDF 1发挥了新的作用，并在成年DG的神经干细胞龛（NSN）中充当神经递质。我们证明，SDF 1与GABA在突触传递到DG NSN中表达CXCR 4的神经祖细胞中合作。这些观察结果表明，无论是HIV 1（T-tropic）或慢性吗啡使用可能直接影响神经发生的影响，这SDF 1利用突触在DG NSN，一个新的目标，我们现在希望追求。 我们还观察到，SDF 1表达的内皮细胞，内衬血管在DG NSN表明SDF 1可能从血管和神经元来源释放可能会影响神经发生。 这些观察结果提出了一个新的目标，在该目标中，我们将从神经元或内皮来源中遗传删除SDF 1，并在正常和病理条件下检查其对神经发生的影响。我们已经创建了一个具有条件性SDF 1等位基因的小鼠品系，现在希望实现这个额外的目标。 我们的新MCP-1-Red/CC 2-绿色小鼠的使用使我们能够检查先天性免疫应答在DG NSN中的作用。先天性免疫应答由HIV 1激活，并将细胞如激活的小胶质细胞和白细胞募集到DG NSN。使用这些小鼠，我们观察到了HIV 1和其他类型的感染或脑损伤对先天免疫反应的激活。形成先天免疫反应的一部分的细胞在病理条件下也可能构成DG NSN的一部分，这是一个新的想法，表明先天免疫可能与成人神经发生相互作用的方式。这些观察结果提出了一个新的目标，我们将研究先天免疫引发的HIV 1和吗啡对DG NSN神经发生的整体影响。我们相信趋化因子信号传导，特别是涉及MCP 1通过CCR 2受体起作用将介导这种作用。 公共卫生相关性。我们已经证明，成年人齿状回干细胞龛中的神经发生可以受到趋化因子SDF 1的影响。表达SDF 1的神经元与GABA合作形成神经前体细胞的突触输入。我们现在希望确定由HIV 1触发的先天免疫反应如何影响成年人DG中神经元的发育，以及如何通过慢性吗啡治疗来改变。我们将利用新的免疫抑制剂来抑制这种免疫反应。趋化因子报告基因和基因敲除小鼠的细胞系，以确定先天免疫系统的细胞成分如何形成成体干细胞生态位的功能部分，以及在正常条件下和神经病理学背景下，趋化因子及其受体如何调节神经源性事件。

DESCRIPTION (provided by applicant): In our original proposal we sought to demonstrate the expression of chemokine receptors by neural progenitor cells in the adult brain, to examine the effect of SDF1/CXCR4 signaling on adult neural progenitor cells in the dentate gyrus (DG), and to investigate the effects of HIV1 on this process. We have successfully pursued these projects. Indeed, this has occurred to such an extent that several new Specific Aims have naturally developed from our work. A significant achievement has been the development of several different lines of two color BAC transgenic mice that report the expression of chemokines (SDF1, MCP1-RED) and their receptors (CXCR4, CCR2-GREEN). These mice allowed us to demonstrate that SDF1 took on a new role and acted as a neurotransmitter within the neural stem cell niche (NSN) of the adult DG. We demonstrated that SDF1 cooperated with GABA in synaptic transmission to CXCR4 expressing neural progenitors in the DG NSN. These observations indicate that both HIV1 (T-tropic) or chronic morphine use may directly influence neurogenesis by impacting this SDF1 utilizing synapse in the DG NSN, a new Aim which we now wish to pursue. We also observed that SDF1 was expressed by endothelial cells that line blood vessels in the DG NSN indicating that SDF1 potentially released from both vascular and neuronal sources may influence neurogenesis. These observations have suggested a new Aim in which we would genetically delete SDF1 from either neuronal or endothelial sources and examine its effects on neurogenesis under normal and pathological conditions. We have created a line of mice with a conditional SDF1 allele and now wish to carry out this additional Aim. The use of our new MCP-1-Red/CC2-Green mice has allowed us to examine the role of the innate immune response in the DG NSN. The innate immune response is activated by HIV1 and recruits cells such as activated microglia and leukocytes to the DG NSN. Using these mice we have observed the activation of the innate immune response by HIV1 and by other types of infection or brain damage. The idea that cells that form part of the innate immune response may also constitute part of the DG NSN under pathological conditions is a new idea suggesting ways in which innate immunity may interact with adult neurogenesis. These observations have suggested a new Aim in which we will examine the overall effect of innate immunity triggered by HIV1 and morphine on neurogenesis in the DG NSN. We believe that chemokine signaling, particularly involving MCP1 acting via the CCR2 receptor will mediate such actions. PUBLIC HEALTH RELEVANCE. We have demonstrated that adult neurogenesis in the dentate gyrus stem cell niche can be influenced by the chemokine SDF1.SDF1 expressing neurons cooperate with GABA in forming synaptic inputs to neural progenitor cells.We now wish to determine how the innate immune response that is triggered by HIV1 can influence the development of neurons in the adult DG and how this can also be modified by chronic morphine treatment.We shall utilize novel lines of chemokine reporter and knockout mice to determine how the cellular elements of the innate immune system can form a functional part of the adult stem cell niche and how neurogenic events can be regulated by chemokines and their receptors under normal conditions and in the context of neuropathology.