LYSOSOMAL PROCESSING OF AMYLOID PRECURSOR PROTEIN TO A-BETA PEPTIDES - A DISTINCT ROLE FOR CATHEPSIN-S
LYSOSOMAL PROCESSING OF AMYLOID PRECURSOR PROTEIN TO A-BETA PEPTIDES - A DISTINCT ROLE FOR CATHEPSIN-S
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DOI：
10.1042/bj3110299
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发表时间：
1995-10-01
影响因子：
4.1
通讯作者：
CHAPMAN, HA
中科院分区：
文献类型：
--
作者：
MUNGER, JS;HAASS, C;CHAPMAN, HA
研究溶酶体区室在淀粉样前体蛋白（APP）加工为淀粉样β肽中的潜在作用（A β），我们稳定过表达一系列溶酶体蛋白酶，（半胱氨酸蛋白酶，组织蛋白酶B、L和S，以及天冬氨酸蛋白酶，组织蛋白酶D）在人肾上皮细胞系中的作用（293）初步实验表明293细胞内源性合成组织蛋白酶B、L和D，但不合成组织蛋白酶S。通过免疫沉淀和ELISA评估A β分泌，发现在组织蛋白酶S表达后增加约2倍，但在其他双转染子中未改变（组织蛋白酶B，L）或减少（组织蛋白酶D）。E-64 d，一种溶酶体半胱氨酸蛋白酶抑制剂，显著降低了组织蛋白酶S转染子的A β分泌，但对表达其他蛋白酶的细胞没有影响。组织蛋白酶S表达细胞分泌的AP的放射性测序显示，以前未报道的从Met-1（相对于最常见的A β N-末端，Asp-1）开始的变体占A β分泌增加的大部分。人脑切片的免疫染色显示组织蛋白酶S存在于阿尔茨海默病患者大脑样本的皮层神经元和神经胶质中。这些结果为活细胞中组织蛋白酶S在内体/溶酶体区室中从β APP的淀粉样蛋白生成片段产生A β的途径提供了证据。该途径似乎是可诱导的，不同于293和其他细胞用于产生A β的组成性途径，并且可能与阿尔茨海默病的发病机制相关。
To investigate the potential contribution of the lysosomal compartment in the processing of amyloid precursor protein (APP) to amyloid beta-peptides (A beta s), we stably overexpressed a series of lysosomal proteases (the cysteine proteases, cathepsins B, L and S, and the aspartic protease, cathepsin D) in a human kidney epithelial cell line (293) transfected to express high levels of beta APP. preliminary experiments indicated that 293 cells endogenously synthesize cathepsins B, L and D, but not cathepsin S. A beta secretion was assessed by immunoprecipitation and ELISA and found to be increased similar to 2-fold following cathepsin S expression, but to be unchanged (cathepsins B, L) or decreased (cathepsin D) in the other double transfectants. E-64d, an inhibitor of lysosomal cysteine proteases, significantly reduced A beta secretion by the cathepsin S transfectants, but had no effect on cells expressing the other proteases. Radiosequencing of AP secreted by cathepsin S-expressing cells revealed that a previously unreported variant beginning at Met -1 (relative to the most common A beta N-terminus, Asp -1) accounted for most of the increase in A beta secretion. Immunostaining of human brain sections revealed cathepsin S in cortical neurons and glia in samples of brain from patients with Alzheimer's disease. These results provide evidence in living cells for a pathway in which cathepsin S generates A beta from amyloidogenic fragments of beta APP in the endosomal/lysosomal compartment. This pathway appears to be inducible, distinct from a constitutive pathway used by 293 and other cells to generate A beta, and may be relevant to the pathogenesis of Alzheimer's disease.