PRESENILINS, CALCIUM HOMEOSTASIS, AND APOPTOSIS

早老素-1(PS-1)基因突变是许多病例的原因 遗传性早发性阿尔茨海默病(AD)。我们的初步数据 显示突变PS-1在PC12细胞中的表达导致改变 内质网(ER)钙调节，这可能与 淀粉样β蛋白(Abeta)诱导的细胞死亡增加 和营养因子戒断(TFW)。拟议的研究测试了 假设，通过扰乱内质网钙稳态和应激 响应，PS-1突变促进线粒体功能障碍，氧自由基 产生和神经元变性。第一个目标将测试 PS-1突变的促凋亡作用是由 内质网钙稳态紊乱促进线粒体受损 功能和增加氧自由基的产生。线粒体功能 参数和氧自由基水平将在PC12细胞和 原代表达突变型或野生型PS-1的小鼠海马神经元 在细胞暴露于凋亡性侮辱之后。我们将决定 基因和药物操作是否会阻止亲和力- 突变型PS-1的凋亡作用。第二个目的是检验假设 IP/3受体在突变体的促凋亡作用中起关键作用 MS-1。我们将研究该基因的表达和亚细胞定位 神经细胞(表达野生型或突变型PS-1)中的IP3R-3 并确定IP3R-3和PS-1是否相互作用以及是否 PS-1突变会影响这种相互作用。第三个目标是测试 内质网葡萄糖调节蛋白(GRP78和GRP94)发挥作用的假说 在保护神经元免受细胞凋亡方面的作用。我们将研究： GRP78和GRP94在神经细胞保护中的作用 抗细胞凋亡。我们将研究：细胞凋亡侮辱对 野生型和突变型PS-1表达神经元的GRP78和Grp94水平； GRP78和GRP94过度表达和“敲除”的后果 细胞对细胞凋亡的脆弱性。最终目的是检验假设 这是通过扰乱内质网钙稳态并诱导氧化 应激，PS突变使神经元对兴奋性毒性易感 活着。给药对海马神经元的损伤 兴奋性毒素或3NP对表达野生型或突变型转基因小鼠的影响 PS-1将被量化。这些研究将建立机制 对PS-1突变对神经元存活的不利影响负责， 并将确定制定预防措施的目标 阿尔茨海默病的神经退行性变。

Mutations in the presenilin-1 (PS-1) gene are responsible for many cases of inherited early onset Alzheimer's disease (AD). Our preliminary data show that expression of mutant PS-1 in PC12 cells results in altered endoplasmic reticulum (ER) calcium regulation, which may be linked to increased of the cells to death induced by amyloid beta-peptide (Abeta) and trophic factor withdrawal (TFW). The proposed studies test the hypothesis that, by perturbing ER calcium homeostasis and stress responses, PS-1 mutations promote mitochondrial dysfunction, oxyradical production and neuronal degeneration. The first aim will test the hypothesis that the pro-apoptotic action of PS-1 mutations results from perturbed ER calcium homeostasis which promotes impaired mitochondrial function and increased oxyradical production. Mitochondrial functional parameters and oxyradical levels will be measured in PC12 cells and primary mouse hippocampal neurons expressing mutant or wild-type PS-1 following exposure of the cells to apoptotic insults. We will determine whether genetic and pharmacological manipulations block the pro- apoptotic actions of mutant PS-1. The second aim tests the hypothesis the IP/3 receptors play a key role in the pro-apoptotic action of mutant MS-1. We will examine the expression and subcellular localization of IP3R-3 in neurons (expressing wild-type or mutant PS-1) undergoing apoptosis; and determine whether IP3R-3 and PS-1 interact and whether PS-1 mutations affect the interaction. The third aim tests the hypothesis that the ER glucose-regulated proteins (grp78 and GRP94) play a role in protecting neurons against apoptosis. We will examine: the effects of apoptotic insults of grp78 and grp94) in protecting neurons against apoptosis. We will examine: the effects of apoptotic insults on grp78 and grp94 levels in neurons expressing wild-type or mutant PS-1; the consequence of grp78 and grp94 over-expression and "knock-out" on cellular vulnerability to apoptosis. The final aim tests the hypothesis that, by perturbing ER calcium homeostasis and inducing oxidative stress, PS mutations render neurons vulnerable to excitotoxicity in vivo. Injury to hippocampal neurons following administration of excitotoxins or 3NP to transgenic mice expressing wild-type or mutant PS-1 will be quantified. These studies will establish mechanisms responsible for adverse effects on PS-1 mutations on neuronal survival, and will identify targets for developing approaches to prevent neurodegeneration in AD.