ORCID Profile
0000-0003-1262-8578
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Publisher: Bentham Science Publishers Ltd.
Date: 04-2005
Abstract: A pilot study was conducted employing a well known mouse model for Alzheimer's disease to evaluate the anti-amyloid efficacy of three FDA pre-approved drugs. Paroxetine (SSRI and APP 5'UTR directed lead compound), N-acetyl cysteine (antioxidant), and erythromycin (macrolide antibiotic) were provided to the drinking water of TgCRND8 mice for three months. This report provides data that measured the steady-state levels of amyloid Abeta-40 and Abeta-42 Abeta as pmol Abeta per gram of mouse brain cortex in drug treated and placebo animals. The relative levels of Abeta peptide levels were reduced after exposure of mice to paroxetine (N=5), NAC (N=7), and erythromycin (N=7) relative to matched placebo counterparts. These results demonstrated proof-of concept for a strategy to further screen the APP 5'UTR target to identify novel drugs that exhibit anti-amyloid efficacy in vivo. These data also demonstrated a statistically significant anti-amyloid trend for paroxetine, NAC and erythromycin. The potential for conducting further studies with these compounds using larger cohorts of TgCRND8 mice is discussed.
Publisher: Elsevier BV
Date: 07-2006
DOI: 10.1016/J.JSB.2005.12.011
Abstract: With the growing aging population in Western countries, Alzheimer's disease (AD) has become a major public health concern. No preventive measure and effective treatment for this burdensome disease is currently available. Genetic, biochemical, and neuropathological data strongly suggest that Abeta amyloidosis, which originates from the amyloidogenic processing of a metalloprotein-amyloid precursor protein (APP), is the key event in AD pathology. However, neurochemical factors that impact upon the age-dependent cerebral Abeta amyloidogenesis are not well recognized. Growing data indicate that cerebral dysregulation of biometals, environmental metal exposure, and oxidative stress contribute to AD pathology. Herein we provided further evidence that both metals (such as Cu) and H(2)O(2) promote formation of neurotoxic Abeta oligomers. Moreover, we first demonstrated that laser capture microdissection coupled with X-ray fluorescence microscopy can be applied to determine elemental profiles (S, Fe, Cu, and Zn) in Abeta amyloid plaques. Clearly the fundamental biochemical mechanisms linking brain biometal metabolism, environmental metal exposure, and AD pathophysiology warrant further investigation. Nevertheless, the study of APP and Abeta metallobiology may identify potential targets for therapeutic intervention and/or provide diagnostic methods for AD.
Publisher: Elsevier BV
Date: 09-2010
Publisher: Springer Science and Business Media LLC
Date: 08-2002
DOI: 10.1007/S12031-002-0014-6
Abstract: We performed a screen for drugs that specifically interact with the 5' untranslated region of the mRNA coding for the Alzheimer's Amyloid Precursor Protein (APP). Using a transfection based assay, in which APP 5'UTR sequences drive the translation of a downstream luciferase reporter gene, we have been screening for new therapeutic compounds that already have FDA approval and are pharmacologically and clinically well-characterized. Several classes of FDA-pre-approved drugs (16 hits) reduced APP 5'UTR-directed luciferase expression (> 95% inhibition of translation). The classes of drugs include known blockers of receptor ligand interactions, bacterial antibiotics, drugs involved in lipid metabolism, and metal chelators. These APP 5'UTR directed drugs exemplify a new strategy to identify RNA-directed agents to lower APP translation and A beta peptide output for Alzheimer's disease therapeutics.
Publisher: Springer Science and Business Media LLC
Date: 03-01-2013
DOI: 10.1038/MP.2011.168
Abstract: The catecholamines dopamine (DA), norepinephrine (NE) and epinephrine (E) are neurotransmitters and hormones that mediate stress responses in tissues and plasma. The expression of β-amyloid precursor protein (APP) is responsive to stress and is high in tissues rich in catecholamines. We recently reported that APP is a ferroxidase, subsuming, in neurons and other cells, the iron-export activity that ceruloplasmin mediates in glia. Here we report that, like ceruloplasmin, APP also oxidizes synthetic amines and catecholamines catalytically (K(m) NE=0.27 mM), through a site encompassing its ferroxidase motif and selectively inhibited by zinc. Accordingly, APP knockout mice have significantly higher levels of DA, NE and E in brain, plasma and select tissues. Consistent with this, these animals have increased resting heart rate and systolic blood pressure as well as suppressed prolactin and lymphocyte levels. These findings support a role for APP in extracellular catecholaminergic clearance.
Publisher: Elsevier BV
Date: 06-2017
Publisher: Wiley
Date: 12-2004
Abstract: The Alzheimer's amyloid precursor protein (APP) is the metalloprotein that is cleaved to generate the pathogenic Abeta peptide. We showed that iron closely regulated the expression of APP by 5'-untranslated region (5'-UTR) sequences in APP mRNA. Iron modulated APP holoprotein expression by a pathway similar to iron control of the translation of the ferritin-L and -H mRNAs by iron-responsive elements in their 5'-UTRs. APP gene transcription is also responsive to copper deficit where the Menkes protein depleted fibroblasts of copper to suppress transcription of APP through metal regulatory and copper regulatory sequences upstream of the APP 5' cap site. APP is a copper-zinc metalloprotein and chelation of Fe(3+) by desferrioxamine and Cu(2+) by clioquinol appeared to provide effective therapy for the treatment of AD in limited patient studies. We have introduced an RNA-based screen for small APP 5'-UTR binding molecules to identify leads that limit APP translation (but not APLP-1 and APLP-2) and amyloid Abeta peptide production. A library of 1200 drugs was screened to identify lead drugs that limited APP 5'-UTR-directed translation of a reporter gene. The efficacy of these leads was confirmed for specificity in a cell-based secondary assay to measure the steady-state levels of APP holoprotein relative to APLP-1/APLP-2 by Western blotting. Several chelators were identified among the APP 5'-UTR directed leads consistent with the presence of an IRE stem-loop in front of the start codon of the APP transcript. The APP 5'-UTR-directed drugs--desferrioxamine (Fe(3+) chelator), tetrathiomolybdate (Cu(2+) chelator), and dimercaptopropanol (Pb(2+) and Hg(2+) chelator)--each suppressed APP holoprotein expression (and lowered Abeta peptide secretion). The novel anticholinesterase phenserine also provided "proof of concept" for our strategy to target the APP 5'-UTR sequence to identify "anti-amyloid" drugs. We further defined the interaction between iron chelation and phenserine action to control APP 5'-UTR-directed translation in neuroblastoma (SY5Y) transfectants. Phenserine was most efficient to block translation under conditions of intracellular iron chelation with desferrioxamine suggesting that this anticholinesterase operated through an iron (metal)-dependent pathway at the APP 5'-UTR site.
Publisher: Frontiers Media SA
Date: 13-08-2018
Publisher: Society for Neuroscience
Date: 25-02-2015
DOI: 10.1523/JNEUROSCI.3439-14.2015
Abstract: Elevation of both neuronal iron and nitric oxide (NO) in the substantia nigra are associated with Parkinson's disease (PD) pathogenesis. We reported previously that the Alzheimer-associated β-amyloid precursor protein (APP) facilitates neuronal iron export. Here we report markedly decreased APP expression in dopaminergic neurons of human PD nigra and that APP −/− mice develop iron-dependent nigral cell loss. Conversely, APP-overexpressing mice are protected in the MPTP PD model. NO suppresses APP translation in mouse MPTP models, explaining how elevated NO causes iron-dependent neurodegeneration in PD.
Publisher: Portland Press Ltd.
Date: 19-11-2008
DOI: 10.1042/BST0361282
Abstract: The essential metals iron, zinc and copper deposit near the Aβ (amyloid β-peptide) plaques in the brain cortex of AD (Alzheimer's disease) patients. Plaque-associated iron and zinc are in neurotoxic excess at 1 mM concentrations. APP (amyloid precursor protein) is a single transmembrane metalloprotein cleaved to generate the 40–42-amino-acid Aβs, which exhibit metal-catalysed neurotoxicity. In health, ubiquitous APP is cleaved in a non-amyloidogenic pathway within its Aβ domain to release the neuroprotective APP ectodomain, APP(s). To adapt and counteract metal-catalysed oxidative stress, as during reperfusion from stroke, iron and cytokines induce the translation of both APP and ferritin (an iron storage protein) by similar mechanisms. We reported that APP was regulated at the translational level by active IL (interleukin)-1 (IL-1-responsive acute box) and IRE (iron-responsive element) RNA stem–loops in the 5′ untranslated region of APP mRNA. The APP IRE is homologous with the canonical IRE RNA stem–loop that binds the iron regulatory proteins (IRP1 and IRP2) to control intracellular iron homoeostasis by modulating ferritin mRNA translation and transferrin receptor mRNA stability. The APP IRE interacts with IRP1 (cytoplasmic cis-aconitase), whereas the canonical H-ferritin IRE RNA stem–loop binds to IRP2 in neural cell lines, and in human brain cortex tissue and in human blood lysates. The same constellation of RNA-binding proteins [IRP1/IRP2 oly(C) binding protein] control ferritin and APP translation with implications for the biology of metals in AD.
Publisher: Elsevier BV
Date: 11-2002
Publisher: Wiley
Date: 03-2004
Abstract: Considerable evidence is mounting that dyshomeostasis of the redox-active biometals, Cu and Fe, and oxidative stress contribute to the neuropathology of Alzheimer's disease (AD). Present data suggest that metals can interact directly with Abeta peptide, the principal component of beta-amyloid that is one of the primary lesions in AD. The binding of metals to Abeta modulates several physiochemical properties of Abeta that are thought to be central to the pathogenicity of the peptide. First, we and others have shown that metals can promote the in vitro aggregation into tinctorial Abeta amyloid. Studies have confirmed that insoluble amyloid plaques in postmortem AD brain are abnormally enriched in Cu, Fe, and Zn. Conversely, metal chelators dissolve these proteinaceous deposits from postmortem AD brain tissue and attenuate cerebral Abeta amyloid burden in APP transgenic mouse models of AD. Second, we have demonstrated that redox-active Cu(II) and, to a lesser extent, Fe(III) are reduced in the presence of Abeta with concomitant production of reactive oxygen species (ROS), hydrogen peroxide (H(2)O(2)) and hydroxyl radical (OH*). These Abeta/metal redox reactions, which are silenced by redox-inert Zn(II), but exacerbated by biological reducing agents, may lead directly to the widespread oxidation damages observed in AD brains. Moreover, studies have also shown that H(2)O(2) mediates Abeta cellular toxicity and increases the production of both Abeta and amyloid precursor protein (APP). Third, the 5' untranslated region (5'UTR) of APP mRNA has a functional iron-response element (IRE), which is consistent with biochemical evidence that APP is a redox-active metalloprotein. Hence, the redox interactions between Abeta, APP, and metals may be at the heart of a pathological positive feedback system wherein Abeta amyloidosis and oxidative stress promote each other. The emergence of redox-active metals as key players in AD pathogenesis strongly argues that amyloid-specific metal-complexing agents and antioxidants be investigated as possible disease-modifying agents for treating this horrible disease.
Publisher: Bentham Science Publishers Ltd.
Date: 07-2006
Publisher: Elsevier BV
Date: 11-2004
DOI: 10.1016/J.EXGER.2004.08.016
Abstract: A growing body of evidence indicates that dysregulation of cerebral biometals (Fe, Cu, Zn) and their interactions with APP and Abeta amyloid may contribute to the Alzheimer's amyloid pathology, and thus metal chelation could be a rational therapeutic approach for interdicting AD pathogenesis. However, poor target specificity and consequential clinical safety of current metal-complexing agents have limited their widespread clinical use. To develop the next generation of metal chelators, we have designed and synthesized a new bifunctional molecule-XH1, based on a novel 'pharmacophore conjugation' concept. This lipophilic molecule has both amyloid-binding and metal-chelating moieties covalently connected by amide bonds. It achieved a putative binding geometry with Abeta1-40 peptide by the computational chemistry modeling and reduced Zn(II)-induced Abeta1-40 aggregation in vitro as determined by turbidometry. Moreover, our pilot data indicated that XH1 has no significant neurotoxicity at low micromolar concentrations and acute animal toxicity. XH1 specifically reduced APP protein expression in human SH-SY5Y neuroblastoma cells and attenuated cerebral Abeta amyloid pathology in PS1/APP transgenic mice without inducing apparent toxicity and behavior disturbances. Collectively, these preliminary findings carry implication for XH1 being a BBB-permeable lead compound for AD therapeutics targeting Alzheimer's amyloidogenesis, although further studies are needed.
Publisher: Bentham Science Publishers Ltd.
Date: 05-2013
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jack Rogers.