In vivo Evaluation of a Newly Synthesized Acetylcholinesterase Inhibitor in a Transgenic Drosophila Model of Alzheimer's Disease.

Giuseppe Uras,Marco Bo,Zsuzsa Markus,Marios Georgiou,Natalie Mack,Jinyi Xu,Alessia Manca,Pengfei Zhang,Shengtao Xu,Stephanie Allen,Zheying Zhu

doi:10.3389/fnins.2021.691222

Abstract

Alzheimer’s disease is a neurodegenerative disease characterized by disrupted memory, learning functions, reduced life expectancy, and locomotor dysfunction, as a result of the accumulation and aggregation of amyloid peptides that cause neuronal damage in neuronal circuits. In the current study, we exploited a transgenic Drosophila melanogaster line, expressing amyloid-β peptides to investigate the efficacy of a newly synthesized acetylcholinesterase inhibitor, named XJP-1, as a potential AD therapy. Behavioral assays and confocal microscopy were used to characterize the drug effect on AD symptomatology and amyloid peptide deposition. The symptomatology induced in this particular transgenic model recapitulates the scenario observed in human AD patients, showing a shortened lifespan and reduced locomotor functions, along with a significant accumulation of amyloid plaques in the brain. XJP-1 treatment resulted in a significant improvement of AD symptoms and a reduction of amyloid plaques by diminishing the amyloid aggregation rate. In comparison with clinically effective AD drugs, our results demonstrated that XJP-1 has similar effects on AD symptomatology, but at 10 times lower drug concentration than donepezil. It also showed an earlier beneficial effect on the reduction of amyloid plaques at 10 days after drug treatment, as observed for donepezil at 20 days, while the other drugs tested have no such effect. As a novel and potent AChE inhibitor, our study demonstrates that inhibition of the enzyme AChE by XJP-1 treatment improves the amyloid-induced symptomatology in Drosophila, by reducing the number of amyloid plaques within the fruit fly CNS. Thus, compound XJP-1 has the therapeutic potential to be further investigated for the treatment of AD.

Highlights

Alzheimer’s disease (AD) is recognized as the worldwide leading cause of dementia, with 5.8 million patients currently affected in the US, with this number expected to double by 2050 (Alzheimer’s Association, 2019)
Flies were kept at 25◦C in 25-ml plastic vials containing 5 ml of standard fly food. elav-Gal4 virgin females were crossed with upstream activating sequence (UAS)-APPE693G males, all stocks were kept at 25◦C, and the female progeny was used for all the assays
To investigate the effects of XJP1 treatment on life expectancy, amyloid-β Arctic (Aβarc) flies were treated with 40 μM of the new AChE inhibitor after testing a range of concentrations (10– 40 μM); 10 to 30 μM did not produce any significant amelioration in pilot lifespan assay

Summary

Introduction

Alzheimer’s disease (AD) is recognized as the worldwide leading cause of dementia, with 5.8 million patients currently affected in the US, with this number expected to double by 2050 (Alzheimer’s Association, 2019). Amyloid plaques are formed of amyloid-β peptides, secreted by neurons, which form insoluble toxic aggregates that lead to local neuroinflammatory and neurodegenerative responses (Sharma et al, 2019). Sequential cleavages of the amyloid precursor protein (APP) performed by β- and γ-secretase is required to generate neurotoxic amyloid-β peptides, which is primarily 40 or 42 amino acids in length (O’Brien and Wong, 2011). Neurofibrillary tangles are composed of a number of fused Tau protein, due to the presence of a hyperphosphorylated form of Tau (Zhang et al, 2016a). Tau is required to stabilize and promote microtubule polymerization, while in AD, Tau is hyperphosphorylated, leading to a disruption of microtubule architecture and stability (Sharma et al, 2019)

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Results

Conclusion