Nuclear 82-kDa choline acetyltransferase decreases amyloidogenic APP metabolism in neurons from APP/PS1 transgenic mice
Nuclear 82-kDa choline acetyltransferase decreases amyloidogenic APP metabolism in neurons from APP/PS1 transgenic mice
复制标题
DOI：
10.1016/j.nbd.2014.05.008
复制
发表时间：
2014-09-01
影响因子：
6.1
通讯作者：
Rylett, R. Jane
中科院分区：
文献类型：
--
作者：
Albers, Shawn;Inthathirath, Fatima;Rylett, R. Jane
阿尔茨海默病（AD）与淀粉样前体蛋白（APP）向β-淀粉样肽（A β）的淀粉样蛋白生成加工增加、胆碱能神经元损失伴胆碱乙酰转移酶（ChAT）活性降低和认知功能障碍相关。69-kDa ChAT和82-kDa ChAT都在人脑和脊髓的胆碱能神经元中表达，其中82-kDa ChAT主要定位于神经元核，这表明该酶具有潜在的替代功能作用。通过基因微阵列分析，我们发现，82 kDa的ChAT表达IMR 32神经细胞有不同的细胞功能参与基因的表达改变。重要的是，调节APP加工的几种蛋白质的基因在含有82-kDa ChAT的细胞中差异表达，这些蛋白质沿着淀粉样蛋白生成和非淀粉样蛋白生成途径。基于观察到的这些基因表达模式的变化，预测的净效应将是淀粉样蛋白生成APP加工减少，A β产生减少。通过实验验证了这种功能结果，即BACE 1蛋白水平和活性显著降低，同时从AD模型APP/PS1转基因小鼠脑中培养的神经元中释放的内源性A β（1-42）减少。神经元中82 kDa ChAT的表达增加了GGA 3的水平，GGA 3参与将BACE 1运输到溶酶体进行降解。shRNA诱导的GGA 3蛋白水平的降低减弱了82 kDa ChAT介导的BACE 1蛋白和活性以及A β（1-42）释放的降低。在表达该ChAT蛋白的SN 56神经细胞中增强的GGA 3基因启动子活性显示了82-kDa ChAT可以增强GGA 3基因表达的证据。这些研究表明胆碱能神经元和APP加工之间存在一种新的关系，82-KDa ChAT作为A β产生的负调节剂。这种A β形成的减少可能导致对胆碱能神经元的保护，以及对附近对A β水平增加敏感的其他细胞的保护。由于年龄增加或神经变性导致的82 kDa ChAT水平降低可能会改变A β产生增加的平衡，从而增强胆碱能神经元功能的下降。(C)2014爱思唯尔公司All rights reserved.
Alzheimer disease (AD) is associated with increased amyloidogenic processing of amyloid precursor protein (APP) to beta-amyloid peptides (A beta), cholinergic neuron loss with decreased choline acetyltransferase (ChAT) activity, and cognitive dysfunction. Both 69-kDa ChAT and 82-kDa ChAT are expressed in cholinergic neurons in human brain and spinal cord with 82-kDa ChAT localized predominantly to neuronal nuclei, suggesting potential alternative functional roles for the enzyme. By gene microarray analysis, we found that 82-kDa ChAT-expressing IMR32 neural cells have altered expression of genes involved in diverse cellular functions. Importantly, genes for several proteins that regulate APP processing along amyloidogenic and non-amyloidogenic pathways are differentially expressed in 82-kDa ChAT-containing cells. The predicted net effect based on observed changes in expression patterns of these genes would be decreased amyloidogenic APP processing with decreased A beta production. This functional outcome was verified experimentally as a significant decrease in BACE1 protein levels and activity and a concomitant reduction in the release of endogenous A beta(1-42) from neurons cultured from brains of AD-model APP/PS1 transgenic mice. The expression of 82-kDa ChAT in neurons increased levels of GGA3, which is involved in trafficking BACE1 to lysosomes for degradation. shRNA-induced decreases in GGA3 protein levels attenuated the 82-kDa ChAT-mediated decreases in BACE1 protein and activity and A beta(1-42) release. Evidence that 82-kDa ChAT can enhance GGA3 gene expression is shown by enhanced GGA3 gene promoter activity in SN56 neural cells expressing this ChAT protein. These studies indicate a novel relationship between cholinergic neurons and APP processing, with 82-KDa ChAT acting as a negative regulator of A beta production. This decreased formation of A beta could result in protection for cholinergic neurons, as well as protection of other cells in the vicinity that are sensitive to increased levels of A beta. Decreasing levels of 82-kDa ChAT due to increasing age or neuro-degeneration could alter the balance towards increasing A beta production, with this potentiating the decline in function of cholinergic neurons. (C) 2014 Elsevier Inc. All rights reserved.