Nasal delivery of a CRMP2-derived CBD3 adenovirus improves cognitive function and pathology in APP/PS1 transgenic mice

Baochang Qi,Xu Wang,Di Sun,Rajesh Khanna,Weina Ju,Yu Yang,Yingying Cheng

doi:10.1186/s13041-020-00596-3

Abstract

Calcium dysregulation is a key pathological event in Alzheimer’s disease (AD). In studying approaches to mitigate this calcium overload, we identified the collapsin response mediator protein 2 (CRMP2), an axonal guidance protein that participates in synapse dynamics by interacting with and regulating activity of N-methyl-D-aspartate receptors (NMDARs). We further identified a 15 amino acid peptide from CRMP2 (designated CBD3, for calcium-binding domain 3), that reduced NMDAR-mediated Ca2+ influx in cultured neurons and post-synaptic NMDAR-mediated currents in cortical slices. Whether targeting CRMP2 could be therapeutically beneficial in AD is unknown. Here, using CBD3, we tested the utility of this approach. Employing the APP/PS1 mouse model of AD which demonstrates robust pathophysiology including Aβ1–42 deposition, altered tau levels, and diminished cognitive functions, we asked if overexpression of CBD3 could rescue these events. CBD3 was engineered into an adeno-associated vector and nasally delivered into APP/PS1 mice and then biochemical (immunohistochemistry, immunoblotting), cellular (TUNEL apoptosis assays), and behavioral (Morris water maze test) assessments were performed. APP/PS1 mice administered adeno-associated virus (AAV, serotype 2) harboring CBD3 demonstrated: (i) reduced levels of Aβ1–42 and phosphorylated-tau (a marker of AD progression), (ii) reduced apoptosis in the hippocampus, and (iii) reduced cognitive decline compared with APP/PS1 mice or APP/PS1 administered a control virus. These results provide an instructive example of utilizing a peptide-based approach to unravel protein-protein interactions that are necessary for AD pathology and demonstrate the therapeutic potential of CRMP2 as a novel protein player in AD.

Highlights

Alzheimer’s disease (AD) has been regarded as an agedependent neurodegenerative disease, and one of the most common forms of dementia, clinically manifesting as progressive cognitive and behavioral impairment [46]
associated viral (AAV) vector construction and validation of the AD model As shown in Fig. 1a, immunoblotting lysates from HEK293 cells transduced with the channel-binding domain 3 (CBD3) or control viruses revealed the presence of a higher molecular weight protein in cells from AAV NT4-TAT-CBD3 infected cells compared to cells infected with AAV NT4-TAT, confirming the expression of the CBD3 peptide
amyloid precursor protein / presenilin 1 (APP/PS1) mice spent more time locating the platform when compared to wildtype (WT) mice, supporting previous findings that the cognitive ability of APP/PS1 mice in spatial learning is significantly reduced

Summary

Introduction

Alzheimer’s disease (AD) has been regarded as an agedependent neurodegenerative disease, and one of the most common forms of dementia, clinically manifesting as progressive cognitive and behavioral impairment [46]. The prevalence of AD generally doubles every 5 years in adults over the age of 65 [31], and it has been estimated that about 152 million people will be living with AD by 2050 [44]. Multiple factors, such as vascular risk factors, lifestyle, and genetic susceptibility have been reported to be involved in AD pathogenesis. To improve the understanding of AD pathogenesis and explore potential curative treatments for it, the amyloid precursor protein / presenilin 1 (APP/PS1) mouse model was constructed to simulate the behavioral and pathological changes observed in AD patients [35, 57]

Methods

Results

Conclusion