期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2015
卷号：112
期号：11
页码：3344-3349
DOI：10.1073/pnas.1502150112
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：SignificanceAmyloid precursor protein (APP) is cleaved by {beta}-secretase to produce APP C99, which undergoes additional, sequential cleavages by {gamma}-secretase to generate amyloid-{beta} peptides including A{beta}40 and A{beta}42. Increased ratios of A{beta}42 over A{beta}40 are thought to cause Alzheimer's disease. Screening of {gamma}-secretase modulators is hindered by the technical challenges in expression and biochemical manipulation of {gamma}-secretase. In this study, we demonstrate that the archaeal intramembrane protease PSH represents an excellent surrogate of {gamma}-secretase in terms of cleavage of APP C99, ratio of A{beta}42 over A{beta}40, and modulation of cleavage preferences by known modulators of {gamma}-secretase. Our finding may facilitate discovery of {gamma}-secretase inhibitors and modulators. Aberrant cleavage of amyloid precursor protein (APP) by {gamma}-secretase contributes to the development of Alzheimer's disease. More than 200 disease-derived mutations have been identified in presenilin (the catalytic subunit of {gamma}-secretase), making modulation of {gamma}-secretase activity a potentially attractive therapeutic opportunity. Unfortunately, the technical challenges in dealing with intact {gamma}-secretase have hindered discovery of modulators and demand a convenient substitute approach. Here we report that, similar to {gamma}-secretase, the archaeal presenilin homolog PSH faithfully processes the substrate APP C99 into A{beta}42, A{beta}40, and A{beta}38. The molar ratio of the cleavage products A{beta}42 over A{beta}40 by PSH is nearly identical to that by {gamma}-secretase. The proteolytic activity of PSH is specifically suppressed by presenilin-specific inhibitors. Known modulators of {gamma}-secretase also modulate PSH similarly in terms of the A{beta}42/A{beta}40 ratio. Structural analysis reveals association of a known {gamma}-secretase inhibitor with PSH between its two catalytic aspartate residues. These findings identify PSH as a surrogate protease for the screening of agents that may regulate the protease activity and the cleavage preference of {gamma}-secretase.
