GLIAL NEURONAL INTERACTIONS IN NEURODEGENERATION

这项研究计划将研究神经元之间的关系 存活率和细胞内钙动态平衡。我们发现这两个人 这些功能在16三体(TS16)的神经元中是有缺陷的 老鼠。TS16小鼠有一个额外的16号染色体副本，即小鼠 人类21号染色体的同源基因。自从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 调节TS16神经元存活的机制可能揭示异常 这会导致AD。 使用一种新的神经元存活体外测试方法，我们发现 TS16小鼠海马神经元死亡速度是对照组的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 作用于神经元的微摩尔浓度谷氨酸促进神经元 海人藻酸/AMPA受体。TS16神经元缺乏这种生存反应 谷氨酸和这一缺陷可以解释TS16的加速死亡 神经元。相比之下，整倍体和TS16神经元都可以通过 多肽生长因子和杀伤剂的兴奋性毒性浓度增加 谷氨酸。使用计算机辅助的Fura-2[钙离子]成像，我们还 发现TS16神经元和TS16神经元的钙稳态均异常 星形胶质细胞。 我们假设促进生存的谷氨酸浓度 维持细胞[Ca~(2+)]-Cyt在最佳范围内可使整倍体神经元存活和 这种反应在TS16神经元中是缺乏的，这是由于基因- 确定存在钙离子内稳态缺陷。这些假说将得到检验。 通过在平行实验中将神经元存活与[Ca~(2+)]相关联 不同程度的生存条件。我们建议进行实验，以 确定谷氨酸促进存活的细胞机制 正常神经元和缺陷存活的机制基础，以及 TS16神经元的钙稳态。 TS16小鼠是一种自然产生的遗传缺陷，它使两种 离散的，但感兴趣的，正常细胞生理的缺陷，即， 降低神经元存活率，改变钙稳态。这两个都是 体内的缺陷可能通过代偿过程被掩盖，这取决于 细胞类型和细胞环境，因此，最容易 在控制良好的条件下进行体外研究。这类赤字 将被加速以使细胞容易受到有毒影响 随着年龄的增长而积累。这种脆弱性可能会在 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.