The Cell-Cycle Control of Astrocytes and Astrocytomas

描述（由申请人提供）：今年，并在每年的 在可预见的未来，将有17,000名美国人患上原发性脑癌。的 其中，最常见的肿瘤是星形细胞瘤。在8,000人中， 被诊断出患有星形细胞瘤，所有人最终都会死于这种疾病。的 星形胶质细胞对转化的脆弱性在于它能够 在生物体生命周期的任何时候重新进入细胞周期。尽管 在增殖能力方面，星形胶质细胞大多保持静止，除了在 对疾病或创伤的反应，其中伴随有神经元损失。一 几年前，我们和其他人证明星形胶质细胞增殖 控制是通过与神经元膜接触来实现的，尽管精确的 神经元发挥这种控制作用的分子机制仍然是难以捉摸的。 我的实验室最近发现了一种受体， 星形胶质细胞，CD 8 1，这是神经元诱导的星形胶质细胞所必需的 细胞周期阻滞（详见初步数据和随附手稿）。 在这个应用中，我们提出了一系列的生物化学，分子和细胞 生物学实验，旨在鉴定和表征 神经元CD 8 1结合蛋白。此外，我们将开始查询 神经元结合后的星形胶质细胞信号传导机制。我们的研究结果 星形胶质细胞表达CD 8 - 1对神经元诱导生长控制的需求 根据我们的观察， 迄今为止，我们检测的星形细胞瘤细胞系绝对下调了 CD 81蛋白与信息。为了确定CD 8 1表达是否可以挽救 这些细胞对细胞周期阻滞引起的神经元反应的能力，我们 已经在星形细胞瘤细胞系中表达了CD 8 1 -GFP融合构建体。的 将测定转染子的体外神经元反应性，和体内神经元反应性。 裸鼠的肿瘤进展和转移。与此同时， 实验中，我们将继续进行一系列的亲和层析纯化 神经元膜蛋白是星形胶质细胞 增殖虽然我们希望并期待我们的两条调查路线 星形胶质细胞生长控制的神经元介质将收敛，这是相当 我们可能会发现涉及到的独立的、冗余的机制， 维持中枢神经系统的数值稳态。

DESCRIPTION (provided by applicant): This year, and in every year in the foreseeable future, 17,000 Americans will develop primary brain cancers. Of these, the most common tumor is astrocytoma. Of the 8,000 people to be diagnosed with astrocytoma, all will eventually die of their disease. The vulnerability of the astrocyte to transformation lies in its ability to re-enter the cell-cycle at any point in the life-time of an organism. In spite of the ability to proliferate, astrocytes are kept mostly quiescent, except in response to disease or trauma, where there is a concomitant neuronal loss. A number of years ago, we and others demonstrated that astrocyte proliferative control is effected by contact with neuronal membranes, although the precise molecular mechanism by which neurons exert this control has remained elusive. My laboratory has recently identified a receptor on the surface of the astrocyte, CD8 1, which is absolutely required for neuron-induced astrocyte cell-cycle arrest (see Preliminary Data, and appended manuscript for details). In this application, we propose a series of biochemical, molecular and cell biological experiments aimed at the identification and characterization of neuronal CD8 1 binding proteins. In addition, we will begin to query the astrocytic signaling mechanism following neuronal binding. Our findings for the requirement for astrocyte expressed CD8 1 for neuron-induced growth control takes on added significance, based on our observation that all of the astrocytoma cell lines we have examined to date have absolutely down regulated CD8 1 protein and message. To determine if CD8 1 expression can rescue the ability of these cells to respond to neuron-induced by cell-cycle arrest, we have expressed a CD8 1 -GFP fusion construct in the astrocytoma cell lines. The transfectants will be assayed for in vitro neuronal responsiveness, and in vivo tumor progression and metastasis in nude mice. In parallel with these experiments, we will continue a series of affinity chromatographic purification of neuronal membrane proteins that are active inhibitors of astrocyte proliferation. While we hope and anticipate that our two lines of inquiry on neuronal mediators of astrocyte growth control will converge, it is quite possible that we will identify separate, redundant mechanisms that are involved in maintaining CNS numerical homeostasis.