Liang Ping, Pan Yang-xing, Zhao Xue-mei, Du Hong-zhen, Zhang Ji-min
Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100005, China.
Zhonghua Bing Li Xue Za Zhi. 2005 May;34(5):297-301.
To study the role of presenilin1 (PS1) in the processing of beta-amyloid precursor protein (APP) to amyloid beta-peptide (Abeta) and its relation to gamma-secretase in the pathogenesis of Alzheimer's disease (AD).
Several CHO cell lines stably transfected with either wide-type or mutant PS1 (M(146)L) along with APP(751) genes were established. The expression of PS1 and its half-life were determined by immunoprecipitation, Western blotting and pulse-chase experiment. Abeta released into the conditional media was quantitated by ELISA.
PS1 transfected CHO cells expressed an expected 45,000 full length protein. This over-expressed full length PS1 was subject to fast degradation with a half-life of less than 1 hour. In contrast to full length PS1, the truncated N-terminal and C-terminal proteins of PS1 were significantly more stable with a longer half-life of nearly 16 hours. Although the total amount of Abeta released into the conditional media did not show a significant difference between wild-type and mutant PS1 (M(146)L) transfected APP cells, mutant PS1 (M(146)L) transfected APP cells increase Abeta(1 - 42) (a subspecies of total Abeta) production with nearly a 2 fold increase, comparing to untransfected or wild-type PS1 transfected APP cells.
PS1 is involved in the processing of APP to Abeta, a nearly 2 fold increase of Abeta production in mutant PS1 (M(146)L) transfected APP cells indicates that PS1 may be the expected gamma-secretase itself.
研究早老素1（PS1）在β-淀粉样前体蛋白（APP）加工生成淀粉样β肽（Aβ）过程中的作用及其与γ-分泌酶在阿尔茨海默病（AD）发病机制中的关系。
构建了几种稳定转染野生型或突变型PS1（M(146)L）以及APP(751)基因的CHO细胞系。通过免疫沉淀、蛋白质印迹和脉冲追踪实验测定PS1的表达及其半衰期。采用酶联免疫吸附测定法对条件培养基中释放的Aβ进行定量分析。
转染PS1的CHO细胞表达预期的45000全长蛋白。这种过表达的全长PS1会快速降解，半衰期小于1小时。与全长PS1相比，PS1的截短型N端和C端蛋白稳定性显著更高，半衰期近16小时。虽然野生型和突变型PS1（M(146)L）转染APP细胞的条件培养基中释放的Aβ总量无显著差异，但与未转染或野生型PS1转染APP细胞相比，突变型PS1（M(146)L）转染APP细胞的Aβ(1 - 42)（总Aβ的一个亚类）生成量增加近2倍。
PS1参与APP加工生成Aβ的过程，突变型PS1（M(146)L）转染APP细胞中Aβ生成量增加近2倍表明PS1可能就是预期的γ-分泌酶本身。
