Distinct mechanisms by mutant presenilin 1 and 2 leading to increased intracellular levels of amyloid β-protein 42 in Chinese hamster ovary cells
Distinct mechanisms by mutant presenilin 1 and 2 leading to increased intracellular levels of amyloid β-protein 42 in Chinese hamster ovary cells
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DOI：
10.1021/bi0267590
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发表时间：
2003-02-04
期刊：
影响因子：
2.9
通讯作者：
Ihara, Y
中科院分区：
文献类型：
--
作者：
Qi, Y;Morishima-Kawashima, M;Ihara, Y
为了研究早老素(PS)1和PS2相关的伽马分泌酶的性质，我们建立了稳定表达淀粉样前体蛋白和野生型(Wt)或突变型(Mt)PSI或PS2的转基因细胞。对mtPS1和mtPS2细胞系中细胞内淀粉样β蛋白(Abeta)水平的定量检测显示存在两种亚型。一组包括PS2基因的N141I、M239V和T122P突变以及PSI、N135D和M233T的同源突变。这些突变导致细胞内Abeta42水平的增加和随之而来的细胞内Abeta40水平的下降。使用这些转染体制备的膜进行的Abeta产生的无细胞检测显示，Abeta42位的裂解占主导地位，Abeta40的产生很少。另一组由PSI的M146L、H163R和G384A突变组成，仅导致细胞内Abeta42水平的增加。M146L细胞内Abeta水平与无细胞Abeta产生结果一致，而H163R和G384A细胞内Abeta水平与无细胞Abeta产生有显著差异。因此，这里研究的所有mtPS1/2都会导致细胞内Abeta42水平的增加。这表明这种共同表型的潜在机制可能是不同的。
To characterize the properties of presenilin (PS) 1- and PS2-associated gamma-secretases, we established stable transfectants overexpressing amyloid precursor protein and wild-type (wt) or a number of mutant (mt) PSI or PS2. Quantification of the intracellular amyloid beta-protein (Abeta) levels in mtPS1 and mtPS2 cell lines revealed the presence of two subtypes. One group consists of N141I, M239V, and T122P mutations of the PS2 gene and homologous mutations of PSI, N135D and M233T. These mutations led to an increase in the intracellular Abeta42 levels and a concomitant decrease in the intracellular Abeta40 levels. A cell-free assay for Abeta production using the membranes prepared from these transfectants exhibited predominant cleavage at position Abeta42 with marginal production of Abeta40. The other group consists of M146L, H163R, and G384A mutations of PSI, leading only to an increase in the intracellular Abeta42 levels. While the intracellular Abeta levels in M146L cells were consistent with the results from cell-free Abeta production, H163R and G384A cells showed significant discrepancies between the intracellular Abeta levels and cell-free Abeta production. Thus, all the mtPS1/2 examined here result in increases in the intracellular Abeta42 levels. This suggests that the underlying mechanisms for this shared phenotype may be diverse.