The ability to investigate therapeutic interventions in animal models of neurodegenerative diseases depends on extensive characterization of the model(s) being used. There are numerous models that have been generated to study Alzheimer’s disease (AD) and the underlying pathogenesis of the disease. While transgenic models have been instrumental in understanding AD mechanisms and risk factors, they are limited in the degree of characteristics displayed in comparison with AD in humans, and the full spectrum of AD effects has yet to be recapitulated in a single mouse model. The Model Organism Development and Evaluation for Late-Onset Alzheimer’s Disease (MODEL-AD) consortium was assembled by the National Institute on Aging (NIA) to develop more robust animal models of AD with increased relevance to human disease, standardize the characterization of AD mouse models, improve preclinical testing in animals, and establish clinically relevant AD biomarkers, among other aims toward enhancing the translational value of AD models in clinical drug design and treatment development. Here we have conducted a detailed characterization of the 5XFAD mouse, including transcriptomics, electroencephalogram, in vivo imaging, biochemical characterization, and behavioral assessments. The data from this study is publicly available through the AD Knowledge Portal.

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Parkinson's disease (PD) is a neurodegenerative disorder characterized by the necrosis of midbrain dopaminergic neurons and subsequent deficiencies of dopamine (DA) signaling, resulting in tremors, rigidity, and bradykinesia among a range of other motor and non-motor complications. Despite its high prevalence and considerable economic burden, driven by a rapidly growing aging population, the underlying molecular mechanisms of PD remain poorly understood, and robust, translational models of the disease have yet to be fully established. These limitations in our collective understanding of PD warrant an urgent need for discovering and interrogating PD-associated druggable targets to address the lack of effective, neuroprotective therapeutics with minimal side effect profiles. Here, we report the development of two high throughput in vivo assays for the discovery of small molecule compounds with therapeutic potential and for probing genes potentially involved in dopaminergic neuroprotection. Transgenic mutant Caenorhabditis elegans (C. elegans) carrying human PD-linked genes were used, one expressing mutant (G2019S) leucine-rich repeat kinase 2 (LRRK2), and the other expressing mutant (A53T) a-synuclein (SNCA). Both strains express GFP exclusively within their dopaminergic neurons allowing for fluorescent signal intensity to serve as a proxy for monitoring dopaminergic neurodegeneration. A control strain (BY250) was used that expressed only dopaminergic neuronal GFP in the absence of PDlinked transgenes. Daily laser cytometry and high-content imaging readings of GFP intensity revealed a robust temporal dopaminergic neurodegeneration in both PD strains, mirroring that which is seen in human PD, within the first seven days of adulthood. By day seven, GFP fluorescent intensity had decreased by 30-50% and 75-85% in the SNCA and LRRK2 worms, respectively; such an effect was not observed in the wild-type control worms. In the LRRK2 mutant worms, we have identified a set of selective LRRK2 kinase inhibitors that may serve as positive controls for neuroprotection. Assay validation and optimization studies are ongoing with the goal of conducting a high throughput screen of small molecules that may confer neuroprotection in our LRRK2 model and serve as scaffolds for the development of drug leads. We have also established effective knockdown of GFP fluorescent signal intensity by the administration of RNA interference (RNAi) via engineered vector bacterial feeding. Due to the low penetrance of RNAi in neurons, we crossed our control and mutant worms into three RNAi hypersensitive backgrounds carrying eri-1, eri-1; lin-15B, and rrf-3 mutations. In a preliminary screen of RNAi vectors, three (ceh-43, unc-62, and ama-1) conferred robust knockdown of GFP signal in both the control and mutant a-synuclein-expressing strains, averaging $75% knockdown by day seven of treatment when compared to an empty vector control RNAi. In the future, we hope to use this assay to screen C. elegans RNAi libraries to elucidate genes that may be neurop...

Background Alzheimer’s disease (AD) is the most common form of dementia without an effective treatment. Animal models of AD have been valuable tools to understand familial or early onset AD, but to date have not been predictive for translational research. The Model Organism Development and Evaluation for Late‐onset AD (MODEL‐AD) Center is developing, validating, and distributing novel mouse models of late‐onset AD (LOAD) that can be used to develop novel therapeutics. Using the 5XFAD model of early onset AD, we have established pipelines to characterize models across multiple sites using biochemistry, histology, functional assays, in vivo MRI and PET imaging, and Serial Two‐Photon (STP) tomography whole brain imaging. Methods At designated time points, animals were subjected to the following assays: Functional ‐ behavioral testing paradigms, and in vivo MRI and PET scanning followed by secondary validation with autoradiography. Biochemistry/Histology ‐ mice were sacrificed, perfused, and tissue harvested, with half of the brain frozen and the other half fixed. On frozen tissue samples we performed bulk RNA‐seq. On fixed tissue samples, we assessed AD relevant changes using the following stains and antibodies: X34 (plaques and NFTs), Lamp1 (dystrophic neurites), Iba1 (microglia). STP Whole Brain Imaging ‐ on additional fixed tissue samples we performed whole brain imaging and regional analysis of Methoxy‐X04 labeled plaques using the TissueCyte® imaging platform. Results Combined assessment of the 5XFAD model revealed systematic neurodegenerative changes in the mouse brain. Multiple data sets including histology, biochemistry, RNA‐seq, transcriptomics, in vivo imaging, and STP whole brain analysis show differences throughout disease progression. Conclusions We utilized the well characterized 5XFAD model of AD to develop an integrated pipeline for deep phenotyping of novel mouse models of AD. This pipeline combines novel functional and anatomical assays across sites to track the ontology of AD progression, and targeted understanding of the molecular, biochemical and functional progression of AD pathology. Together, this pipeline provides a novel platform for greater understanding of LOAD mouse models and potential therapeutic approaches for AD.