NEUROTROPHIC FACTOR DEPRIVATION AND NEURONAL CELL DEATH

这个项目的长期目标是发现分子 营养因子支持神经元存活的机制 当失去营养支持时，哪些神经元会发生凋亡死亡 特别是，我们将检验这些假设(由最近的工作提出 来自我们自己和其他实验室的)：a)神经元经历凋亡 当他们不适当地试图重新进入细胞周期时死亡；b) 神经生长因子等营养因子通过将神经元排除在 细胞周期；c)营养因子的退出导致神经元 试图重新进入细胞周期，但他们这样做是不适当的 协调方式，并经历细胞凋亡性死亡。对这些假设的检验 将使用大鼠PC12嗜铬细胞瘤细胞和 需要神经生长因子(NGF)的啮齿动物交感神经元 它们的营养支持。具体目标包括：(1)。研究其作用机制 N-乙酰半胱氨酸使神经细胞免于凋亡性死亡 由于营养支持的丧失而引起的。特别是，为了确定 这种药物的促存活作用是否直接归因于它的 抗氧化性能或使其间接能力增强 细胞内谷胱甘肽的水平，以及(正如我们所认为的)它的 促进生存的作用归功于它的能力(最近发现 由我们)，以阻止细胞增殖。(2)。以确定是否 阻止神经细胞的操作(药理学和分子) 从进入或重新进入细胞周期(尤其是从 进入S阶段)，将防止他们因 营养支持的退出。这将在一定程度上通过 干扰特异性G0-G1期的表达和/或活性 包括细胞周期蛋白和细胞周期蛋白依赖性激酶在内的调控分子 (CDK)。(3)。以确定营养因子和其他因素是否 通过对神经细胞的特殊作用来防止神经元的凋亡 细胞周期和参与调节细胞的特定分子 周而复始。我们坚信，对 营养因子防止神经元死亡的机制(S) 当营养支持被剥夺时神经元死亡将提供手段 开发合适的药物疗法来预防或改善 神经退行性疾病。如果一个人能做到这一点，情况就尤其如此。 确定细胞周期相关分子参与细胞周期调控 神经元的生死。

The long-term goals of this project are to uncover the molecular mechanisms by which trophic factors support neuronal survival and by which neurons undergo apoptotic death when deprived of trophic support In particular, we shall test the hypotheses (suggested by recent work from our own and other laboratories) that: a) Neurons undergo apoptotic death when they inappropriately attempt to reenter the cell cycle; b) Trophic factors such as NGF promote survival by keeping neurons out of the cell cycle; c) Withdrawal of trophic factors causes neurons to attempt to re-enter the cell cycle, but they do so in an inappropriately coordinated manner and undergo apoptotic death. Tests of these hypotheses will be carried out using cultures of rat Pc12 pheochromocytoma cells and rodent sympathetic neurons that require nerve growth factor (NGF) for their trophic support. Specific aims include: (1). To study the mechanism by which N-acetylcysteine rescues neuronal cells from apoptotic death caused by withdrawal of trophic support. In particular, to determine whether the survival-promoting actions of this drug are due to its direct anti-oxidative properties or to its indirect ability to increase intracellular levels of glutathione, and whether (as we believe) its survival-promoting actions are due to its ability (recently discovered by us) to block cellular proliferation. (2). To determine whether manipulations (pharmacological and molecular) that prevent neuronal cells from entering or re-entering the cell cycle (and in particular, from entering S phase), will prevent their apoptotic death caused by withdrawal of trophic support. This will be accomplished in part by interfering with the expression and/or activity of specific G0-G1 phase regulatory molecules including cyclins and cyclin-dependent kinases (Cdks). (3). To determine whether trophic factors and other agents that prevent neuronal apoptotic death do so by means of specific effects on cell cycle and on specific molecules that are involved in regulating cell cycle. We are of the conviction that a clear understanding of the mechanism(s) by which trophic factors prevent neuronal death and by which neurons perish when deprived of trophic support will provide mean& to develop suitable pharmacologic therapies to prevent or ameliorate neurodegenerative conditions. This will be especially so if one can establish involvement of cell cycle-related molecules in governance of neuronal life and death.