Pharmacology and Therapeutics - Research Publications
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ItemThe hypoxia imaging agent CuII(atsm) is neuroprotective and improves motor and cognitive functions in multiple animal models of Parkinson's disease(ROCKEFELLER UNIV PRESS, 2012-04-09)Parkinson's disease (PD) is a progressive, chronic disease characterized by dyskinesia, rigidity, instability, and tremors. The disease is defined by the presence of Lewy bodies, which primarily consist of aggregated α-synuclein protein, and is accompanied by the loss of monoaminergic neurons. Current therapeutic strategies only give symptomatic relief of motor impairment and do not address the underlying neurodegeneration. Hence, we have identified Cu(II)(atsm) as a potential therapeutic for PD. Drug administration to four different animal models of PD resulted in improved motor and cognition function, rescued nigral cell loss, and improved dopamine metabolism. In vitro, this compound is able to inhibit the effects of peroxynitrite-driven toxicity, including the formation of nitrated α-synuclein oligomers. Our results show that Cu(II)(atsm) is effective in reversing parkinsonian defects in animal models and has the potential to be a successful treatment of PD.
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ItemNo Preview AvailableCopper Promotes the Trafficking of the Amyloid Precursor Protein(AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2011-03-11)Accumulation of the amyloid β peptide in the cortical and hippocampal regions of the brain is a major pathological feature of Alzheimer disease. Amyloid β peptide is generated from the sequential protease cleavage of the amyloid precursor protein (APP). We reported previously that copper increases the level of APP at the cell surface. Here we report that copper, but not iron or zinc, promotes APP trafficking in cultured polarized epithelial cells and neuronal cells. In SH-SY5Y neuronal cells and primary cortical neurons, copper promoted a redistribution of APP from a perinuclear localization to a wider distribution, including neurites. Importantly, a change in APP localization was not attributed to an up-regulation of APP protein synthesis. Using live cell imaging and endocytosis assays, we found that copper promotes an increase in cell surface APP by increasing its exocytosis and reducing its endocytosis, respectively. This study identifies a novel mechanism by which copper regulates the localization and presumably the function of APP, which is of major significance for understanding the role of APP in copper homeostasis and the role of copper in Alzheimer disease.
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ItemHigh Order W02-Reactive Stable Oligomers of Amyloid-β are Produced in vivo and in vitro via Dialysis and Filtration of Synthetic Amyloid-β Monomer(IOS PRESS, 2015)Oligomeric forms of amyloid-β (Aβ) are thought to be responsible for the pathogenesis of Alzheimer's disease. While many oligomers of Aβ are thought to be naturally occurring in the brain of humans and/or transgenic animals, it is well known that Aβ oligomers are also readily produced in vitro in the laboratory. In recent studies, we discovered that synthetic monomeric Aβ (4.7 kDa) could be transformed by microdialysis to higher molecular weight species (approximately 56 kDa, by western blot). Surface-enhanced laser desorption/ionization mass spectrometry and electron microscopy further identified these species' as potential Aβ oligomers. The production of similar species could also be produced by centrifugal filtration and this formation was concentration and pore-size dependent. These higher order species of Aβ were resistant to dissolution in NaOH, HFIP, formic acid, urea, and guanidine. We postulate that we have identified a novel way of producing a high order species of oligomeric Aβ and we provide evidence to suggest that Aβ oligomers can quite easily be a product of normal laboratory practices. These data suggest that the experimental detection of higher order oligomers in tissues derived from Alzheimer's disease brains or from animal models of disease could, in some cases, be a product the method of analysis.
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ItemAmyloid-Beta Peptide Aβ3pE-42 Induces Lipid Peroxidation, Membrane Permeabilization and Calcium-Influx in Neurons(American Society for Biochemistry and Molecular Biology, 2016)Pyroglutamate-modified amyloid-β (pE-Aβ) is a highly neurotoxic amyloid-β (Aβ) isoform and is enriched in the brains of individuals with Alzheimer disease compared with healthy aged controls. Pyroglutamate formation increases the rate of Aβ oligomerization and alters the interactions of Aβ with Cu(2+) and lipids; however, a link between these properties and the toxicity of pE-Aβ peptides has not been established. We report here that Aβ3pE-42 has an enhanced capacity to cause lipid peroxidation in primary cortical mouse neurons compared with the full-length isoform (Aβ(1-42)). In contrast, Aβ(1-42) caused a significant elevation in cytosolic reactive oxygen species, whereas Aβ3pE-42 did not. We also report that Aβ3pE-42 preferentially associates with neuronal membranes and triggers Ca(2+) influx that can be partially blocked by the N-methyl-d-aspartate receptor antagonist MK-801. Aβ3pE-42 further caused a loss of plasma membrane integrity and remained bound to neurons at significantly higher levels than Aβ(1-42) over extended incubations. Pyroglutamate formation was additionally found to increase the relative efficiency of Aβ-dityrosine oligomer formation mediated by copper-redox cycling.
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ItemTraumatic brain injury induces elevation of Co in the human brain(ROYAL SOC CHEMISTRY, 2015)Traumatic brain injury (TBI) is the most common cause of death and disability in young adults, yet the molecular mechanisms that follow TBI are poorly understood. We previously reported a perturbation in iron (Fe) levels following TBI. Here we report that the distribution of cobalt (Co) is modulated in post-mortem human brain following injury. We also investigated how the distribution of other biologically relevant elements changes in TBI. Cobalt is increased due to TBI while copper (Cu), magnesium (Mg), manganese (Mn), phosphorus (P), potassium (K), rubidium (Rb), selenium (Se) and zinc (Zn) remain unchanged. The elevated Co has important implications for positron emission tomography neuroimaging. This is the first demonstration of the accumulation of Co in injured tissue explaining the previous utility of (55)Co-PET imaging in TBI.
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ItemUtility of an improved model of amyloid-beta (Aβ1-42) toxicity in Caenorhabditis elegans for drug screening for Alzheimer's disease(BMC, 2012-11-21)BACKGROUND: The definitive indicator of Alzheimer's disease (AD) pathology is the profuse accumulation of amyloid-ß (Aß) within the brain. Various in vitro and cell-based models have been proposed for high throughput drug screening for potential therapeutic benefit in diseases of protein misfolding. Caenorhabditis elegans offers a convenient in vivo system for examination of Aß accumulation and toxicity in a complex multicellular organism. Ease of culturing and a short life cycle make this animal model well suited to rapid screening of candidate compounds. RESULTS: We have generated a new transgenic strain of C. elegans that expresses full length Aß₁₋₄₂. This strain differs from existing Aß models that predominantly express amino-truncated Aß₃₋₄₂. The Aß₁₋₄₂ is expressed in body wall muscle cells, where it oligomerizes, aggregates and results in severe, and fully penetrant, age progressive-paralysis. The in vivo accumulation of Aß₁₋₄₂ also stains positive for amyloid dyes, consistent with in vivo fibril formation. The utility of this model for identification of potential protective compounds was examined using the investigational Alzheimer's therapeutic PBT2, shown to be neuroprotective in mouse models of AD and significantly improve cognition in AD patients. We observed that treatment with PBT2 provided rapid and significant protection against the Aß-induced toxicity in C. elegans. CONCLUSION: This C. elegans model of full length Aß₁₋₄₂ expression can now be adopted for use in screens to rapidly identify and assist in development of potential therapeutics and to study underlying toxic mechanism(s) of Aß.
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ItemOral Treatment with CuII(atsm) Increases Mutant SOD1 In Vivo but Protects Motor Neurons and Improves the Phenotype of a Transgenic Mouse Model of Amyotrophic Lateral Sclerosis(SOC NEUROSCIENCE, 2014-06-04)Mutations in the metallo-protein Cu/Zn-superoxide dismutase (SOD1) cause amyotrophic lateral sclerosis (ALS) in humans and an expression level-dependent phenotype in transgenic rodents. We show that oral treatment with the therapeutic agent diacetyl-bis(4-methylthiosemicarbazonato)copper(II) [Cu(II)(atsm)] increased the concentration of mutant SOD1 (SOD1G37R) in ALS model mice, but paradoxically improved locomotor function and survival of the mice. To determine why the mice with increased levels of mutant SOD1 had an improved phenotype, we analyzed tissues by mass spectrometry. These analyses revealed most SOD1 in the spinal cord tissue of the SOD1G37R mice was Cu deficient. Treating with Cu(II)(atsm) decreased the pool of Cu-deficient SOD1 and increased the pool of fully metallated (holo) SOD1. Tracking isotopically enriched (65)Cu(II)(atsm) confirmed the increase in holo-SOD1 involved transfer of Cu from Cu(II)(atsm) to SOD1, suggesting the improved locomotor function and survival of the Cu(II)(atsm)-treated SOD1G37R mice involved, at least in part, the ability of the compound to improve the Cu content of the mutant SOD1. This was supported by improved survival of SOD1G37R mice that expressed the human gene for the Cu uptake protein CTR1. Improving the metal content of mutant SOD1 in vivo with Cu(II)(atsm) did not decrease levels of misfolded SOD1. These outcomes indicate the metal content of SOD1 may be a greater determinant of the toxicity of the protein in mutant SOD1-associated forms of ALS than the mutations themselves. Improving the metal content of SOD1 therefore represents a valid therapeutic strategy for treating ALS caused by SOD1.
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Itemβ-amyloid in biological samples: not all Aβ detection methods are created equal(FRONTIERS MEDIA SA, 2014-08-13)