Oxidative stress mechanisms related to ribotoxic stress and endoplasmic reticulum stress

与核糖应激和内质网应激相关的氧化应激机制

基本信息

批准号：
13470196
负责人：
TAKEDA Masatoshi
金额：
$ 10.24万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

项目摘要

Neurofibliraly tangles (NFTs) and neuronal cell death are hallmark of Alzheimer's disease (AD) and abnormal hyperphospholylated tau protein is the major subunit of NFT. However the mechanisms of phosphorylation of tau in neurodegenerative process of AD is unknown. We investigated the changes of phosphorylation of tau protein and neuronal cell death in SY5Y human neuroblastoma cells treated with peptidyltransferase inhibitors including anisomycin and T2-triol. Western blot analysis revealed that anisomycin and T2-triol induced activation of SAPK and p38 MAPK and hyperphosphorylation of tau protein at the M4 (Thr-231/Ser-235), the PHF-1 (Ser-396/404) and the S422 (Ser-422) site. The inhibitor of p38, SB203580, attenuated the phosphorylation of tau protein in this response, whereas an inhibition of GSK-3, lithium, did not. In this response the number of apoptotic cells visualized by Hoechst33342 was less than *he number of total dead cells visualized by Live/Dead kit (Molecular Probe), suggesting the non-apoptotoc cell death mechanism might be involved. This peptidyltransferase-inhibition is one kind of ribotoxic stresses. Further the cells were treated with rose bengal and light, and singlet oxygen was induced. Under this condition, ribosomal RNA was oxidized and tau protein was phosphorylated, probably through ribotoxic stress. In AD brain hyperphosphorylation of tau protein and neuronal cell death might be explained by this ribotoxic stress mechanism.

神经软化缠结（NFTS）和神经元细胞死亡是阿尔茨海默氏病（AD）的标志，而异常的高磷酸化tau蛋白是NFT的主要亚基。但是，tau在AD的神经退行性过程中的磷酸化机制尚不清楚。我们研究了用肽基转移酶抑制剂在内的SY5Y人神经母细胞瘤细胞中Tau蛋白和神经元细胞死亡的磷酸化变化，包括苯甲霉素和T2-三醇。 Western印迹分析表明，在M4（THR-231/SER-235），PHF-1（SER-396/404）和S422（SER-422）（SER-422）位点，Anisomycin和T2-三醇诱导SAPK和P38 MAPK的激活以及Tau蛋白的过度磷酸化。 p38，SB203580的抑制剂在此反应中减弱了tau蛋白的磷酸化，而GSK-3，锂的抑制作用却没有。在这一响应中，Hoechst33342可视化的凋亡细胞的数量少于 *通过活/死试剂盒（分子探针）可视化的死细胞的数量，这表明可能涉及非托托托细胞死亡机制。这种肽基转移酶抑制是一种核糖毒性应激。此外，将细胞用玫瑰孟加拉和光处理，并诱导单线氧。在这种情况下，核糖体RNA被氧化并可能通过核毒性应激磷酸化。在AD脑中，Tau蛋白和神经元细胞死亡的高磷酸化可能通过这种核糖毒性应激机制来解释。