Glial Cell Function on SVZ Neurogenesis

描述(申请人提供)：出生后脑室下区(SVZ)是一个生发中心，由迁移和增殖的神经母细胞链组成，被胶质纤维酸性蛋白免疫阳性(GFAP+)细胞包裹，显示出干细胞的特征。祖细胞在整个SVZ和沿吻端迁移流(RMS)向嗅球迁移，在那里它们在一生中不断地替换中间神经元。识别影响SVZ祖细胞行为的信号将有助于更好地了解影响嗅球间神经元替换的机制，并且对于设计促进神经发生和自我修复的策略是必要的。祖细胞的产生被认为是由在神经母细胞和GFAP+细胞之间提供通讯信号的分子调控的，然而我们对这种信号的了解仍然很初级。这项资助的中心假设是，从GFAP+细胞到神经母细胞的谷氨酸能信号通过促进出生后SVZ前体细胞的增殖来平衡GABA的抑制功能。将解决三个目标。首先，我们将确定是否存在从GFAP+细胞到神经母细胞的快速谷氨酸能信号。当神经母细胞通过GABA能信号向GFAP+细胞传递信号时，谷氨酸能信号将为这两种细胞之间的双向交流提供必要的反馈回路。其次，我们将确定SVZ细胞释放的PGE2是否调节GFAP+细胞的谷氨酸释放，从而调节mGluR的激活。最后，我们将确定谷氨酸和前列腺素E_2的S对谷氨酸释放的调节是否对细胞增殖起到积极的控制作用，以抵消GABA的抑制影响。我们将使用膜片钳和钙离子成像技术，并在脑片和体内进行增殖分析。我们将使用CD1小鼠和几种转基因小鼠来实现我们的目标。希望通过这些实验，我们可以确定GFAP+细胞和神经母细胞之间双向通讯的存在和功能，并进一步了解细胞间信号如何调控出生后的神经发生。

DESCRIPTION (provided by applicant): The postnatal subventricular zone (SVZ) is a germinal center composed of a network of chains of migrating and proliferative neuroblasts ensheathed by glial fibrillary acidic protein immunopositive (GFAP+) cells, which display the characteristics of stem cells. The progenitors migrate throughout the SVZ and along the rostral migratory stream (RMS) toward the olfactory bulb where they continuously replace interneurons throughout life. Identifying the signals influencing the behavior of SVZ progenitors would lead to a better basic understanding of the mechanisms influencing replacement of olfactory bulb interneurons, and is necessary to design strategies to promote neurogenesis and self-repair. The production of progenitors is thought to be regulated by molecules providing communication signals between neuroblasts and GFAP+ cells, yet our knowledge of such signaling remains rudimentary. The central hypothesis of this grant is that glutamatergic signaling from GFAP+ cells to neuroblasts balances GABA's inhibitory function by promoting the proliferation of postnatal SVZ progenitors. Three aims will be addressed. First we will determine whether a fast glutamatergic signaling from GFAP+ cells to neuroblast exists. As neuroblasts signal to GFAP+ cells via GABAergic signaling, glutamatergic signaling would provide a feedback loop necessary for a bidirectional communication between these two cell types. Second, we will determine whether PGE2 released from SVZ cells modulates glutamate release from GFAP+ cells and thus mGluR activation. Finally, we will determine whether glutamate and PGE2's modulation of glutamate release provide a positive control on cell proliferation to counterbalance GABA's inhibitory influence. We will use patch-clamp and Ca2+ imaging techniques, and perform proliferation assays in brain slices and in vivo. We will use CD1 mice and several lines of transgenic mice to address our aims. It is hoped that together the proposed experiments will identify the existence and function of a bidirectional communication between GFAP+ cells and neuroblasts, and further our understanding of how intercellular signaling regulates postnatal neurogenesis.