β-secretase cleavage at amino acid residue 34 in the amyloid β peptide is dependent upon γ-secretase activity
β-secretase cleavage at amino acid residue 34 in the amyloid β peptide is dependent upon γ-secretase activity
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DOI：
10.1074/jbc.m209859200
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发表时间：
2003-06-06
影响因子：
4.8
通讯作者：
Hazuda, DJ
中科院分区：
文献类型：
--
作者：
Shi, XP;Tugusheva, K;Hazuda, DJ
淀粉样β肽（Abeta）是阿尔茨海默病特征的老年斑的主要成分。β肽是由β和γ分泌酶裂解淀粉样蛋白前体蛋白（APP）产生的。β -分泌酶（BACE）是一种i型跨膜天冬氨酸蛋白酶，它首先裂解APP，生成含有β肽N端的99个氨基酸的膜相关片段（CT99）。γ -分泌酶是一种多蛋白复合物，然后在CT99的跨膜区域分裂，产生β肽的C端。因此，β肽的产生依赖于BACE和γ分泌酶的活性。BACE对APP的裂解被认为是γ -分泌酶介导的加工的先决条件。在本研究中，我们在体外和细胞中提供了证据，证明bace介导的Abeta区域氨基酸残基34和35 （Abeta-34位点）之间的裂解依赖于γ -分泌酶活性。体外，Abeta-34位点被BACE1和BACE2特异性加工，而不被组织蛋白酶D（一种密切相关的天冬氨酸蛋白酶）加工。此外，BACE1或BACE2仅在β 1-40肽（γ -分泌酶的裂解产物）作为底物时，而不是以未裂解的CT99作为底物，才能裂解Abeta-34位点。在细胞中，过表达BACE1或BACE2可显著增加Abeta 1-34的产生。更重要的是，由BACE1或BACE2过表达诱导的Abeta 1 - 34种的细胞生成被许多已知的γ -分泌酶抑制剂以浓度依赖的方式阻断。这些γ -分泌酶抑制剂在体外对BACE1或BACE2的酶活性没有影响。因此，我们的数据表明-分泌酶切割CT99是bace介导的Abeta- 34位点加工的先决条件。因此，BACE和γ -分泌酶活性可以相互依赖。
The amyloid beta peptides (Abeta) are the major components of the senile plaques characteristic of Alzheimer's disease. Abeta peptides are generated from the cleavage of amyloid precursor protein (APP) by beta- and gamma-secretases. beta-Secretase ( BACE), a type-I transmembrane aspartyl protease, cleaves APP first to generate a 99-amino acid membrane-associated fragment (CT99) containing the N terminus of Abeta peptides. gamma-Secretase, a multi-protein complex, then cleaves within the transmembrane region of CT99 to generate the C termini of Abeta peptides. The production of Abeta peptides is, therefore, dependent on the activities of both BACE and gamma-secretase. The cleavage of APP by BACE is believed to be a prerequisite for gamma-secretase-mediated processing. In the present study, we provide evidence both in vitro and in cells that BACE-mediated cleavage between amino acid residues 34 and 35 ( Abeta-34 site) in the Abeta region is dependent on gamma-secretase activity. In vitro, the Abeta-34 site is processed specifically by BACE1 and BACE2, but not by cathepsin D, a closely related aspartyl protease. Moreover, the cleavage of the Abeta-34 site by BACE1 or BACE2 occurred only when Abeta 1-40 peptide, a gamma-secretase cleavage product, was used as substrate, not the non-cleaved CT99. In cells, overexpression of BACE1 or BACE2 dramatically increased the production of the Abeta 1-34 species. More importantly, the cellular production of Abeta 1 - 34 species induced by overexpression of BACE1 or BACE2 was blocked by a number of known gamma-secretase inhibitors in a concentration-dependent manner. These gamma-secretase inhibitors had no effect on enzymatic activity of BACE1 or BACE2 in vitro. Our data thus suggest that gamma-secretase cleavage of CT99 is a prerequisite for BACE-mediated processing at Abeta- 34 site. Therefore, BACE and gamma-secretase activity can be mutually dependent.