Trushina, Eugenia

AbstractBackgroundWe have previously demonstrated that partial reduction of mitochondrial complex I (MCI) activity using small molecules is efficacious in decreasing levels of amyloid beta (Aβ), phosphorylated Tau, augmenting mitochondrial bioenergetics, promoting resistance to oxidative stress and restoring mitochondrial axonal trafficking, levels of BDNF and synaptic proteins in pre‐symptomatic APP/PS1 mice. In parallel, these mice demonstrated an improved cognitive and behavioral phenotype compared to their untreated littermates.MethodIn the current study, we tested whether treatment with MCI inhibitors could halt the disease progression when treatment was administered to symptomatic APP/PS1 mice.ResultTreatment improved glucose tolerance, prevented body weight loss, and ameliorated systemic inflammation. Treatment improved glucose uptake in the brain measured using FDG‐PET imaging. Electrophysiological recording in hippocampus indicated that synaptic activity and LTP were restored in treated APP/PS1 mice. Data gathered using 3D electron microscopy reconstruction of dendrites in CA1 region of hippocampus showed that treatment increased the population of mature dendritic spines in APP/PS1 mice, which correlates with restored synaptic activity and improved glucose uptake and utilization in the brain. Immunohistochemical analysis showed that treated APP/PS1 mice had reduced brain level of Aβ plaques, markers of inflammation and reduced degeneration of TH+ neurons in locus coeruleus. The RNA‐seq gene function enrichment analysis showed that pathways down‐regulated by treatment with MCI inhibitors in APP/PS1 mice included the ones involved in oxidative stress and immune system response. Moreover, RNA‐seq data analysis depicted a cluster of genes involved in dendritic morphology, axonal guidance and neuronal development, which expression were reverted by treatment in APP/PS1 mice to the level observed in NTG mice. Western blot analysis in cortico‐hippocampal brain region of APP/PS1 mice confirmed that treatment increased signaling molecules involved in IGF‐1/insulin pathway, mitochondrial biogenesis, oxidative stress protection, autophagy and synaptic function.ConclusionOverall, our data suggest that long‐term treatment with MCI inhibitors is safe and efficacious in restoring cognitive function and preventing degeneration in symptomatic APP/PS1 mice. Therefore, partial MCI inhibitors represent a promising therapeutic approach to ameliorate AD and promote healthy aging.

AbstractBackgroundAlzheimer’s Disease (AD) has no effective treatments, and recent clinical trials focused on prevention of amyloid beta (Ab) production have consistently failed. Alternative approaches are urgently needed. We developed small molecules partial mitochondrial complex I (MCI) inhibitors and demonstrated that their application prevents the development of cognitive and behavior phenotype, improves LTP, reduces oxidative stress and inflammation, and restores glucose uptake and utilization in the brain in mouse models of familial AD. Efficacy could be monitored in vivo using translational biomarkers FDG‐PET, 31P NMR and blood biomarkers.MethodWe conducted extensive structure‐activity relationship (SAR) studies to characterize novel classes of compounds partial MCI inhibitors including a new lead compound C458. Target engagement, selectivity and specificity of new compounds were established using multiple in vitro and cellular assays including SPR, competitive and direct binding, proteomics and pull down experiments.ResultWe demonstrated that the lead C458 directly binds and competes with the FMN for binding to complex I. In primary neurons and mouse brain tissue, single dose administration of C458 activates AMPK‐a, autophagy, Sirtuins 1 and 3, and upregulate PGC‐1a leading to enhanced mitochondrial biogenesis. In vivo, chronic administration of C458 had no detectable toxicity at therapeutic doses. C458 has excellent oral bioavailability and blood–brain‐barrier penetration. C458 was remarkably clean in 250 kinase panel. Finally, in pre‐symptomatic APP/PS1 mice, treatment with C458 resulted in cognitive protection and improved long‐term potentiation after 6 months of chronic oral administration (25 mg/kg/day), decreased oxidative stress and inflammation. Furthermore, APP/PS1 mice treated with C458 showed a significant increase in metabolic rates and glucose brain uptake and utilization detected with translational FDG‐PET imaging as well as an enhancement of ATP production in the brain measured in vivo with 31P NMR.ConclusionMechanistic studies demonstrate that MCI inhibitors induce protective stress response increasing mitochondrial biogenesis and turnover, augmenting cellular energetics and the protection against oxidative stress, and engage other mechanisms that intersect with the pathways involved in longevity and health extension. Our studies demonstrate that modulation of MCI activity using novel FMN MCI inhibitors improves bioenergetics in the brain and averts cognitive decline in Alzheimer’s Disease representing novel therapeutic approach.

Background: Accumulation of hyperphosphorylated tau (pTau) protein is associated with synaptic dysfunction in Alzheimer’s disease (AD). We previously demonstrated that neuroprotection in familial mouse models of AD could be achieved by targeting mitochondria complex I (MCI) and activating the adaptive stress response. Efficacy of this strategy on pTau-related pathology remained unknown. Objective: To investigate the effect of specific MCI inhibitor tricyclic pyrone compound CP2 on levels of human pTau, memory function, long term potentiation (LTP), and energy homeostasis in 18-month-old 3xTg-AD mice and explore the potential mechanisms. Methods: CP2 was administered to male and female 3xTg-AD mice from 3.5–18 months of age. Cognitive function was assessed using the Morris water maze. Glucose metabolism was measured in periphery using a glucose tolerance test and in the brain using fluorodeoxyglucose F18 positron-emission tomography (FDG-PET). LTP was evaluated using electrophysiology in the hippocampus. The expression of key proteins associated with neuroprotective mechanisms were assessed by western blotting. Results: Chronic CP2 treatment restored synaptic activity in female 3xTg-AD mice; cognitive function, levels of synaptic proteins, glucose metabolism, and energy homeostasis were improved in male and female 3xTg-AD mice. Significant reduction of human pTau in the brain was associated with increased activity of protein phosphatase of type 2A (PP2A), and reduced activity of cyclin-dependent kinase 5 (CDK5) and glycogen synthase kinase 3β (GSK3β). Conclusion: CP2 treatment protected against synaptic dysfunction and memory impairment in symptomatic 3xTg-AD mice, and reduced levels of human pTau, indicating that targeting mitochondria with small molecule specific MCI inhibitors represents a promising strategy for treating AD.

Abstract Introduction Development of efficacious therapeutic interventions for Alzheimer's disease (AD) is hampered by the lack of understanding early disease mechanisms, biomarkers, and models that mimic complex pathophysiology of human disease. Methods This article aims to assess to what extent peripheral cells recapitulate molecular mechanisms altered in the brain and could be used as translational models for the development of individualized medicine for AD. Results Multiple studies suggest that AD is a systemic disorder with an active crosstalk between brain and periphery where multiple pathways altered in the brain cells are also affected in plasma, cerebrospinal fluid, and other peripheral cells of AD patients. Discussion Additional studies to validate molecular mechanisms in peripheral cells using advanced system biology techniques and well‐characterized cohorts of AD patients together with the development of standardized protocols should be considered to support the application of peripheral cells in AD research.