Identification of novel intercellular signaling molecules of the animal central nervous system

除了神经元外，大脑还含有几种称为神经胶质的非神经元支持细胞，它们分泌生长因子和神经元存活所需的其他分子。然而，胶质细胞也可以被诱导分泌神经毒性物质。胶质细胞是否促进神经元存活或损伤取决于其周围环境中存在的刺激。参与神经胶质-神经元和神经胶质-神经胶质通讯的细胞间信号分子的确切网络仍有待阐明。具体而言，以下问题尚未得到解答：1）由刺激和/或受损的胶质细胞和神经元释放的哪些分子被周围的胶质细胞识别; 2）如果胶质细胞对不同的内源性分子有不同的反应，这种反应的关键特征是什么？该研究计划的总体目标是鉴定在动物脑中作为细胞间信号的新型蛋白质，并探索其作用的细胞和分子机制。通过合作，我已经确定了两种候选蛋白质，线粒体转录因子（TFAM）和细胞色素c，它们通常隐藏在称为线粒体的细胞器内，但一旦从细胞中释放出来，就可以与神经胶质相互作用。拟议研究计划的两个具体目标将产生支持或驳回这两种和其他候选蛋白质作为脑细胞使用的信号分子的数据。我和我的学生将鉴定参与胶质细胞-TFAM相互作用的受体和细胞内信号通路。还将TFAM蛋白注射到大鼠脑中，并测量细胞反应。在第三个目标下，将使用大规模蛋白质分析（蛋白质组学）来鉴定TFAM及其相关分子诱导的神经胶质分泌的变化。总的来说，这项研究将确定属于大脑细胞间信号分子网络的蛋白质。所产生的数据将通过提供有关这些网络的基础知识而使神经生物学领域受益。此外，这项研究计划可以通过确定改变或改善大脑功能的分子靶点，使所有加拿大人受益。

In addition to neurons, the brain contains several types of non-neuronal support cells called glia that secrete growth factors and other molecules needed for neuronal survival. However, glia can also be induced to secrete neurotoxic substances. Whether glia promote neuronal survival or damage depends on the stimuli present in their surrounding environment. The exact network of intercellular signaling molecules involved in glia-neuronal and glia-glial communication remains to be elucidated. Specifically, the following questions are unanswered: 1) What molecules released by stimulated and/or damaged glia and neurons are recognized by surrounding glia; 2) If glia respond differently to distinct endogenous molecules, what are the key features of such responses? The OVERALL OBJECTIVE of the proposed research program is to identify novel proteins that function as intercellular signals in the animal brain and explore their cellular and molecular mechanisms of action. Through collaborative work, I have already identified two candidate proteins, mitochondrial transcription factor (TFAM) and cytochrome c, which are normally hidden inside cell organelles called mitochondria, but could interact with glia once released from cells. Two of the specific objectives of the proposed research program will generate data that either support or dismiss these two and other candidate proteins as signaling molecules used by brain cells. My students and I will identify the receptors and intracellular signaling pathways involved in glia-TFAM interactions. TFAM protein will also be injected into rat brains and cellular responses will be measured. Under the third objective, large-scale protein analysis (proteomics) will be used to identify changes in glial secretions induced by TFAM and its associated molecules. Overall, this research will identify proteins that belong to the network of intercellular signaling molecules of the brain. The data generated will benefit the field of neurobiology by providing fundamental knowledge about these networks. Moreover, this research program could lead to practical applications benefitting all Canadians through identification of molecular targets for altering or improving brain function.