Poksay Karen S, Sheffler Douglas J, Spilman Patricia, Campagna Jesus, Jagodzinska Barbara, Descamps Olivier, Gorostiza Olivia, Matalis Alex, Mullenix Michael, Bredesen Dale E, Cosford Nicholas D P, John Varghese
Bredesen Lab, Buck Institute for Research on Aging, Novato CA, USA.
Cancer Metabolism and Signaling Networks Program, Sanford Burnham Prebys Medical Discovery Institute, La Jolla CA, USA.
Front Pharmacol. 2017 Feb 15;8:46. doi: 10.3389/fphar.2017.00046. eCollection 2017.
Alzheimer's disease (AD) is characterized by neuronal and synaptic loss. One process that could contribute to this loss is the intracellular caspase cleavage of the amyloid precursor protein (APP) resulting in release of the toxic C-terminal 31-amino acid peptide APP-C31 along with the production of APPΔC31, full-length APP minus the C-terminal 31 amino acids. We previously found that a mutation in APP that prevents this caspase cleavage ameliorated synaptic loss and cognitive impairment in a murine AD model. Thus, inhibition of this cleavage is a reasonable target for new therapeutic development. In order to identify small molecules that inhibit the generation of APP-C31, we first used an APPΔC31 cleavage site-specific antibody to develop an AlphaLISA to screen several chemical compound libraries for the level of N-terminal fragment production. This antibody was also used to develop an ELISA for validation studies. In both high throughput screening (HTS) and validation testing, the ability of compounds to inhibit simvastatin- (HTS) or cerivastatin- (validation studies) induced caspase cleavage at the APP-D720 cleavage site was determined in Chinese hamster ovary (CHO) cells stably transfected with wildtype (wt) human APP (CHO-7W). Several compounds, as well as control pan-caspase inhibitor Q-VD-OPh, inhibited APPΔC31 production (measured fragment) and rescued cell death in a dose-dependent manner. The effective compounds fell into several classes including SERCA inhibitors, inhibitors of Wnt signaling, and calcium channel antagonists. Further studies are underway to evaluate the efficacy of lead compounds - identified here using cells and tissues expressing wt human APP - in mouse models of AD expressing mutated human APP, as well as to identify additional compounds and determine the mechanisms by which they exert their effects.
阿尔茨海默病(AD)的特征是神经元和突触丧失。导致这种丧失的一个过程是淀粉样前体蛋白(APP)的细胞内半胱天冬酶切割,导致有毒的C末端31个氨基酸肽APP-C31释放,同时产生APPΔC31,即全长APP减去C末端31个氨基酸。我们之前发现,APP中的一种突变可阻止这种半胱天冬酶切割,从而改善了小鼠AD模型中的突触丧失和认知障碍。因此,抑制这种切割是新治疗方法开发的一个合理靶点。为了鉴定抑制APP-C31生成的小分子,我们首先使用一种APPΔC31切割位点特异性抗体开发了一种AlphaLISA,以筛选几个化合物库中N末端片段的产生水平。该抗体还用于开发用于验证研究的ELISA。在高通量筛选(HTS)和验证测试中,在稳定转染野生型(wt)人APP(CHO-7W)的中国仓鼠卵巢(CHO)细胞中,测定化合物抑制辛伐他汀(HTS)或西立伐他汀(验证研究)诱导的APP-D720切割位点半胱天冬酶切割的能力。几种化合物以及对照泛半胱天冬酶抑制剂Q-VD-OPh以剂量依赖性方式抑制APPΔC31的产生(测量片段)并挽救细胞死亡。有效的化合物分为几类,包括SERCA抑制剂、Wnt信号通路抑制剂和钙通道拮抗剂。正在进行进一步的研究,以评估在此使用表达wt人APP的细胞和组织鉴定的先导化合物在表达突变人APP的AD小鼠模型中的疗效,以及鉴定其他化合物并确定它们发挥作用的机制。