GLIAL NEURONAL INTERACTIONS IN NEURODEGENERATION

这项研究计划将探讨神经元之间的关系， 存活和细胞内Ca 2+稳态。 我们发现， 这些功能在来自16三体（Ts 16）的神经元中有缺陷 老鼠. Ts 16小鼠有一个额外的16号染色体拷贝， 人类21号染色体的同源物。 由于21三体患者（下降 综合征）不可避免地发展为阿尔茨海默病（AD）， 以神经元死亡为特征的神经退行性疾病，理解 调节Ts 16神经元存活的机制可能揭示了 这有助于AD。 使用一种新的体外神经元存活测定法，我们发现， Ts 16小鼠海马神经元的死亡速度比对照组快2-3倍， 正常（整倍体）神经元。 我们的数据表明整倍体的存活率 神经元是促进微摩尔浓度的谷氨酸作用， 红藻氨酸/AMPA受体。 Ts 16神经元缺乏这种存活反应， 谷氨酸和这种赤字可以解释Ts 16的加速死亡 神经元 相比之下，整倍体和Ts 16神经元都被 肽生长因子和杀死兴奋毒性浓度的添加 谷氨酸盐。 使用计算机辅助fura-2 [Ca 2 +]成像，我们还 发现Ts 16神经元和 星形胶质细胞 我们假设促进存活的谷氨酸浓度 将[Ca 2 +]cyt维持在整倍体神经元存活的最佳范围内， 这种反应在Ts 16神经元中是缺乏的，这是由于遗传上的- 确定的Ca 2+稳态缺陷。 这些假设将得到检验 通过在平行实验中将神经元存活与[Ca 2 +] 不同程度的生存条件。我们提出实验， 确定谷氨酸促进存活的细胞机制 正常神经元和有缺陷的生存机制的基础， Ts 16神经元内Ca ~（2+）的稳态。 Ts 16小鼠是一种自然发生的遗传缺陷， 正常细胞生理学上的离散但感兴趣的缺陷，即， 降低神经元存活和改变Ca 2+稳态。 这两 在体内，这些缺陷可能被代偿过程所掩盖， 细胞类型和细胞环境，因此， 在受控条件下进行体外研究。 这种赤字 会加速细胞对有毒物质的反应， 随着年龄的增长而积累。 这种脆弱性可能在 神经退行性疾病的发展。

This research program will investigate the relationship between neuron survival and intracellular Ca2+ homeostasis. We have found that both of these functions are defective in neurons from the trisomy 16 (Ts16) mouse. The Ts16 mouse has an extra copy of chromosome 16, the mouse homolog of human chromosome 21. Since patients with trisomy 21 (down syndrome) inevitable develop Alzeheimer's disease (AD), a neurodegenerative disorder characterized by neuronal death, understanding the mechanisms regulating Ts16 neuron survival may reveal abnormalities that contribute to AD. Using a novel in vitro assay for neuron survival, we have discovered that hippocampal neurons from the Ts16 mouse die 2-3 times faster than do normal (euploid) neurons. Our data demonstrate that survival of euploid neurons is promoted by micromolar concentrations of glutamate acting at kainate/AMPA receptors. Ts16 neurons lack this survival response to glutamate and this deficit can account for the accelerated death of Ts16 neurons. In contrast, both euploid and Ts16 neurons are rescued by peptide growth factors and killed by excitotoxic concentrations of added glutamate. Using computer-assisted fura-2 [Ca2+] imaging, we have also discovered that Ca2+ homeostasis is abnormal in both Ts16 neurons and astrocytes. We hypothesize that survival-promoting concentrations of glutamate maintain [Ca2+]cyt in an optimal range for euploid neuron survival and that this response is lacking in Ts16 neurons due to a genetically- determined defect in Ca2+ homeostasis. These hypotheses will be tested by correlating neuron survival with [Ca2+] in parallel experiments under conditions of varying degrees of survival. We propose experiments to determine the cellular mechanism underlying glutamate-promoted survival of normal neurons and the mechanistic basis for defective survival and Ca2+ homeostasis in Ts16 neurons. The Ts16 mouse is a naturally-occurring genetic defect that confers two discrete, but interested, deficits n normal cell physiology, viz., decreased neuronal survival and altered Ca2+ homeostasis. Both of these deficits may be masked in vivo by compensatory processes depending on cell type and cellular environment and, therefore, are most easily studied in vitro under well-controlled conditions. Deficits of this kind would be expedited to make cells vulnerable to toxic influences that accumulate with aging. Such vulnerability may play a role in the development of neurodegenerate disorders.