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Santos SF, Pierrot N, Octave JN. Network excitability dysfunction in Alzheimer's disease: insights from in vitro and in vivo models. Rev Neurosci 2010; 21:153-71. [PMID: 20879690 DOI: 10.1515/revneuro.2010.21.3.153] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
UNLABELLED Recent reports have drawn attention to dysfunctions of intrinsic neuronal excitability and network activity in Alzheimer disease (AD). Here we review the possible causes of these basic dysfunctions and implications for AD, based on in vitro and in vivo findings. We then review the current therapeutic approaches particularly linked to the issue of neuronal excitability in AD. CONCLUSION AD is a complex, neurodegenerative disorder. Hippocampal synaptic dysfunction is an early feature of the degenerative process that is clearly linked to memory impairment, the first and major symptom of AD. A growing body of evidence points toward a dysfunction of neuronal networks. Intrinsic neuronal excitability, mainly through profound dysregulation of calcium homeostasis, appears to be largely affected. Consequently, neuronal communication is disturbed. Such cellular defects might underlie cognitive manifestations like fluctuations in cognitive impairment and might also explain several observations obtained with EEG, MEG, MRI, or PET studies, leading to the concept of a disconnection syndrome in AD.
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Affiliation(s)
- Susana Ferrao Santos
- Université catholique de Louvain, Institute of Neuroscience, B-1200 Brussels, Belgium.
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52
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Taler-Verčič A, Zerovnik E. Binding of amyloid peptides to domain-swapped dimers of other amyloid-forming proteins may prevent their neurotoxicity. Bioessays 2010; 32:1020-4. [PMID: 21086533 DOI: 10.1002/bies.201000079] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Ajda Taler-Verčič
- Department of Biochemistry, Molecular and Structural Biology, Jožef Stefan Institute, Ljubljana, Slovenia
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53
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Spatial correlation between brain aerobic glycolysis and amyloid-β (Aβ ) deposition. Proc Natl Acad Sci U S A 2010; 107:17763-7. [PMID: 20837517 DOI: 10.1073/pnas.1010461107] [Citation(s) in RCA: 293] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Amyloid-β (Aβ) plaque deposition can precede the clinical manifestations of dementia of the Alzheimer type (DAT) by many years and can be associated with changes in brain metabolism. Both the Aβ plaque deposition and the changes in metabolism appear to be concentrated in the brain's default-mode network. In contrast to prior studies of brain metabolism which viewed brain metabolism from a unitary perspective that equated glucose utilization with oxygen consumption, we here report on regional glucose use apart from that entering oxidative phosphorylation (so-called "aerobic glycolysis"). Using PET, we found that the spatial distribution of aerobic glycolysis in normal young adults correlates spatially with Aβ deposition in individuals with DAT and cognitively normal participants with elevated Aβ, suggesting a possible link between regional aerobic glycolysis in young adulthood and later development of Alzheimer pathology.
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54
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Bobba A, Petragallo VA, Marra E, Atlante A. Alzheimer's proteins, oxidative stress, and mitochondrial dysfunction interplay in a neuronal model of Alzheimer's disease. Int J Alzheimers Dis 2010; 2010. [PMID: 20862336 PMCID: PMC2939402 DOI: 10.4061/2010/621870] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/24/2010] [Accepted: 07/09/2010] [Indexed: 11/20/2022] Open
Abstract
In this paper, we discuss the interplay between beta-amyloid (Aβ) peptide, Tau fragments, oxidative stress, and mitochondria in the neuronal model of cerebellar granule neurons (CGNs) in which the molecular events reminiscent of AD are activated. The identification of the death route and the cause/effect relationships between the events leading to death could be helpful to manage the progression of apoptosis in neurodegeneration and to define antiapoptotic treatments acting on precocious steps of the death process. Mitochondrial dysfunction is among the earliest events linked to AD and might play a causative role in disease onset and progression. Recent studies on CGNs have shown that adenine nucleotide translocator (ANT) impairment, due to interaction with toxic N-ter Tau fragment, contributes in a significant manner to bioenergetic failure and mitochondrial dysfunction. These findings open a window for new therapeutic strategies aimed at preserving and/or improving mitochondrial function.
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Affiliation(s)
- Antonella Bobba
- Istituto di Biomembrane e Bioenergetica, CNR, Via Amendola 165/A, 70126 Bari, Italy
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55
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Randall AD, Witton J, Booth C, Hynes-Allen A, Brown JT. The functional neurophysiology of the amyloid precursor protein (APP) processing pathway. Neuropharmacology 2010; 59:243-67. [PMID: 20167227 DOI: 10.1016/j.neuropharm.2010.02.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/12/2023]
Abstract
Amyloid beta (Abeta) peptides derived from proteolytic cleavage of amyloid precursor protein (APP) are thought to be a pivotal toxic species in the pathogenesis of Alzheimer's disease (AD). Furthermore, evidence has been accumulating that components of APP processing pathway are involved in non-pathological normal function of the CNS. In this review we aim to cover the extensive body of research aimed at understanding how components of this pathway contribute to neurophysiological function of the CNS in health and disease. We briefly outline changes to clinical neurophysiology seen in AD patients before discussing functional changes in mouse models of AD which range from changes to basal synaptic transmission and synaptic plasticity through to abnormal synchronous network activity. We then describe the various neurophysiological actions that are produced by application of exogenous Abeta in various forms, and finally discuss a number or other neurophysiological aspects of the APP pathway, including functional activities of components of secretase complexes other than Abeta production.
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Affiliation(s)
- A D Randall
- MRC Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol School of Medical Sciences, Bristol, UK.
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56
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Poulopoulou C, Markakis I, Davaki P, Tsaltas E, Rombos A, Hatzimanolis A, Vassilopoulos D. Aberrant modulation of a delayed rectifier potassium channel by glutamate in Alzheimer's disease. Neurobiol Dis 2010; 37:339-48. [DOI: 10.1016/j.nbd.2009.10.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Revised: 09/08/2009] [Accepted: 10/10/2009] [Indexed: 12/21/2022] Open
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57
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Oxidation of potassium channels by ROS: a general mechanism of aging and neurodegeneration? Trends Cell Biol 2010; 20:45-51. [DOI: 10.1016/j.tcb.2009.09.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 09/23/2009] [Accepted: 09/24/2009] [Indexed: 12/13/2022]
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58
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Cole SL, Vassar R. Linking vascular disorders and Alzheimer's disease: potential involvement of BACE1. Neurobiol Aging 2009; 30:1535-44. [PMID: 18289733 PMCID: PMC3490488 DOI: 10.1016/j.neurobiolaging.2007.12.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2007] [Revised: 11/28/2007] [Accepted: 12/14/2007] [Indexed: 01/26/2023]
Abstract
The etiology of Alzheimer's disease (AD) remains unknown. However, specific risk factors have been identified, and aging is the strongest AD risk factor. The majority of cardiovascular events occur in older people and a close relationship between vascular disorders and AD exists. Amyloid plaques, composed of the beta amyloid peptide (Abeta), are hallmark lesions in AD and evidence indicates that Abeta plays a central role in AD pathophysiology. The BACE1 enzyme is essential for Abeta generation, and BACE1 levels are elevated in AD brain. The cause(s) of this BACE1 elevation remains undetermined. Here we review the potential contribution of vascular disease to AD pathogenesis. We examine the putative vasoactive properties of Abeta and how the cellular changes associated with vascular disease may elevate BACE1 levels. Despite increasing evidence, the exact role(s) vascular disorders play in AD remains to be determined. However, given that vascular diseases can be addressed by lifestyle and pharmacologic interventions, the potential benefits of these therapies in delaying the clinical appearance and progression of AD may warrant investigation.
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Affiliation(s)
- Sarah L Cole
- Northwestern University, The Feinberg School of Medicine, Department of Cell and Molecular Biology, 303 E. Chicago Avenue, Chicago, IL 60611, USA.
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59
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Abstract
Alzheimer and prion diseases are neurodegenerative disorders characterised by the abnormal processing of amyloid-beta (Abeta) peptide and prion protein (PrP(C)), respectively. Recent evidence indicates that PrP(C) may play a critical role in the pathogenesis of Alzheimer disease. PrP(C) interacts with and inhibits the beta-secretase BACE1, the rate-limiting enzyme in the production of Abeta. More recently PrP(C) was identified as a receptor for Abeta oligomers and the expression of PrP(C) appears to be controlled by the amyloid intracellular domain (AICD). Here we review these observations and propose a feedback loop in the normal brain where PrP(C) exerts an inhibitory effect on BACE1 to decrease both Abeta and AICD production. In turn, the AICD upregulates PrP(C) expression, thus maintaining the inhibitory effect of PrP(C) on BACE1. In Alzheimer disease, this feedback loop is disrupted, and the increased level of Abeta oligomers bind to PrP(C) and prevent it from regulating BACE1 activity.
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Affiliation(s)
- Katherine A B Kellett
- Institute of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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60
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Pieri M, Amadoro G, Carunchio I, Ciotti MT, Quaresima S, Florenzano F, Calissano P, Possenti R, Zona C, Severini C. SP protects cerebellar granule cells against beta-amyloid-induced apoptosis by down-regulation and reduced activity of Kv4 potassium channels. Neuropharmacology 2009; 58:268-76. [PMID: 19576909 DOI: 10.1016/j.neuropharm.2009.06.029] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 06/12/2009] [Accepted: 06/24/2009] [Indexed: 10/20/2022]
Abstract
The tachykinin endecapeptide substance P (SP) has been demonstrated to exert a functional role in neurodegenerative disorders, including Alzheimer's disease (AD). Aim of the present study was to evaluate the SP neuroprotective potential against apoptosis induced by the neurotoxic beta-amyloid peptide (A beta) in cultured rat cerebellar granule cells (CGCs). We found that SP protects CGCs against both A beta(25-35)- and A beta(1-42)-induced apoptotic CGCs death as revealed by live/dead cell assay, Hoechst staining and caspase(s)-induced PARP-1 cleavage, through an Akt-dependent mechanism. Since in CGCs the fast inactivating or A-type K(+) current (I(KA)) was potentiated by A beta treatment through up-regulation of Kv4 subunits, we investigated whether I(KA) and the related potassium channel subunits could be involved in the SP anti-apoptotic activity. Patch-clamp experiments showed that the A beta-induced increase of I(KA) current amplitude was reversed by SP treatment. In addition, as revealed by Western blot analysis and immunofluorescence studies, SP prevented the up-regulation of Kv4.2 and Kv4.3 channel subunits expression. These results indicate that SP plays a role in the regulation of voltage-gated potassium channels in A beta-mediated neuronal death and may represent a new approach in the understanding and treatment of AD.
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Affiliation(s)
- M Pieri
- Department of Neuroscience, University of Rome Tor Vergata, Via Montpellier, 1, 00133, Rome, Italy
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61
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Minkeviciene R, Rheims S, Dobszay MB, Zilberter M, Hartikainen J, Fülöp L, Penke B, Zilberter Y, Harkany T, Pitkänen A, Tanila H. Amyloid beta-induced neuronal hyperexcitability triggers progressive epilepsy. J Neurosci 2009; 29:3453-62. [PMID: 19295151 PMCID: PMC6665248 DOI: 10.1523/jneurosci.5215-08.2009] [Citation(s) in RCA: 472] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2008] [Revised: 01/05/2009] [Accepted: 02/08/2009] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease is associated with an increased risk of unprovoked seizures. However, the underlying mechanisms of seizure induction remain elusive. Here, we performed video-EEG recordings in mice carrying mutant human APPswe and PS1dE9 genes (APdE9 mice) and their wild-type littermates to determine the prevalence of unprovoked seizures. In two recording episodes at the onset of amyloid beta (Abeta) pathogenesis (3 and 4.5 months of age), at least one unprovoked seizure was detected in 65% of APdE9 mice, of which 46% had multiple seizures and 38% had a generalized seizure. None of the wild-type mice had seizures. In a subset of APdE9 mice, seizure phenotype was associated with a loss of calbindin-D28k immunoreactivity in dentate granular cells and ectopic expression of neuropeptide Y in mossy fibers. In APdE9 mice, persistently decreased resting membrane potential in neocortical layer 2/3 pyramidal cells and dentate granule cells underpinned increased network excitability as identified by patch-clamp electrophysiology. At stimulus strengths evoking single-component EPSPs in wild-type littermates, APdE9 mice exhibited decreased action potential threshold and burst firing of pyramidal cells. Bath application (1 h) of Abeta1-42 or Abeta25-35 (proto-)fibrils but not oligomers induced significant membrane depolarization of pyramidal cells and increased the activity of excitatory cell populations as measured by extracellular field recordings in the juvenile rodent brain, confirming the pathogenic significance of bath-applied Abeta (proto-)fibrils. Overall, these data identify fibrillar Abeta as a pathogenic entity powerfully altering neuronal membrane properties such that hyperexcitability of pyramidal cells culminates in epileptiform activity.
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Affiliation(s)
| | - Sylvain Rheims
- Faculté de Sciences de Luminy, Aix Marseille Université, and
| | - Marton B. Dobszay
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, S-17177 Stockholm, Sweden
| | - Misha Zilberter
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, S-17177 Stockholm, Sweden
| | | | | | - Botond Penke
- Supramolecular and Nanostructured Materials Research Group of the Hungarian Academy of Science, University of Szeged, H-6720 Szeged, Hungary
| | - Yuri Zilberter
- Institut National de la Santé et de la Recherche Médicale, Institut de Neurobiologie de la Méditerranée U901, F-13000 Marseille, France
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, S-17177 Stockholm, Sweden
| | - Tibor Harkany
- Division of Molecular Neurobiology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, S-17177 Stockholm, Sweden
- Institute of Medical Sciences, College of Life Sciences & Medicine, University of Aberdeen, Aberdeen, AB25 2ZD, United Kingdom
| | - Asla Pitkänen
- A. I. Virtanen Institute, University of Kuopio, and
- Department of Neurology, Kuopio University Hospital, FIN-70211 Kuopio, Finland
| | - Heikki Tanila
- A. I. Virtanen Institute, University of Kuopio, and
- Department of Neurology, Kuopio University Hospital, FIN-70211 Kuopio, Finland
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62
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Abstract
The Alzheimer's disease related peptide amyloid beta (Abeta) might have a physiological role in upregulating K channel currents in neurones. Earlier studies used the human form of Abeta1-40 on rat neurones. We sought to confirm our hypothesis by use of rat Abeta, which has no Alzheimer's association. In rat cerebellar granule neurones and HEK293 cells expressing Kv4.2 subunits, whole-cell patch clamp of K currents revealed that preincubation of cells with recombinant human or rat Abeta1-40 (10 nM for 24 h) significantly increased K channel current density. This was accompanied by increased mRNA levels for Kv4.2. These data indicate that rodent and human Abeta are effective in modulating K currents. The effectiveness of nonaggregating rat Abeta also strongly supports a physiological role for the peptide.
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63
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Sanz-Blasco S, Valero RA, Rodríguez-Crespo I, Villalobos C, Núñez L. Mitochondrial Ca2+ overload underlies Abeta oligomers neurotoxicity providing an unexpected mechanism of neuroprotection by NSAIDs. PLoS One 2008; 3:e2718. [PMID: 18648507 PMCID: PMC2447871 DOI: 10.1371/journal.pone.0002718] [Citation(s) in RCA: 158] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 06/20/2008] [Indexed: 12/01/2022] Open
Abstract
Dysregulation of intracellular Ca2+ homeostasis may underlie amyloid β peptide (Aβ) toxicity in Alzheimer's Disease (AD) but the mechanism is unknown. In search for this mechanism we found that Aβ1–42 oligomers, the assembly state correlating best with cognitive decline in AD, but not Aβ fibrils, induce a massive entry of Ca2+ in neurons and promote mitochondrial Ca2+ overload as shown by bioluminescence imaging of targeted aequorin in individual neurons. Aβ oligomers induce also mitochondrial permeability transition, cytochrome c release, apoptosis and cell death. Mitochondrial depolarization prevents mitochondrial Ca2+ overload, cytochrome c release and cell death. In addition, we found that a series of non-steroidal anti-inflammatory drugs (NSAIDs) including salicylate, sulindac sulfide, indomethacin, ibuprofen and R-flurbiprofen depolarize mitochondria and inhibit mitochondrial Ca2+ overload, cytochrome c release and cell death induced by Aβ oligomers. Our results indicate that i) mitochondrial Ca2+ overload underlies the neurotoxicity induced by Aβ oligomers and ii) inhibition of mitochondrial Ca2+ overload provides a novel mechanism of neuroprotection by NSAIDs against Aβ oligomers and AD.
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Affiliation(s)
- Sara Sanz-Blasco
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Ruth A. Valero
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
| | - Ignacio Rodríguez-Crespo
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Madrid, Spain
| | - Carlos Villalobos
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
- * E-mail:
| | - Lucía Núñez
- Instituto de Biología y Genética Molecular (IBGM), Universidad de Valladolid and Consejo Superior de Investigaciones Científicas (CSIC), Valladolid, Spain
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64
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Kobayashi D, Zeller M, Cole T, Buttini M, McConlogue L, Sinha S, Freedman S, Morris RGM, Chen KS. BACE1 gene deletion: Impact on behavioral function in a model of Alzheimer's disease. Neurobiol Aging 2008; 29:861-73. [PMID: 17331621 DOI: 10.1016/j.neurobiolaging.2007.01.002] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Revised: 11/15/2006] [Accepted: 01/13/2007] [Indexed: 10/23/2022]
Abstract
Accumulation of cerebral amyloid-beta (Abeta) has been implicated as a putative causal factor in the development of Alzheimer's disease (AD). Transgenic mice like the PDAPP line overexpress human mutant Amyloid Precursor Protein (hAPP) and recapitulate many features of AD, including amyloid neuropathology and cognitive deficits. Inhibition of the beta-site aspartyl cleaving enzyme (BACE1) enzyme responsible for the first proteolytic cleavage that ultimately generates Abeta has been proposed as a strategy for AD therapy. To assess the theoretical repercussions of beta-secretase activity reduction in an in vivo model of AD, BACE1(-/-) mice bred to the PDAPP line were examined in a series of behavioral tasks. Although BACE1 gene ablation abolished hAbeta accumulation, BACE1(-/-) mice had unexpected sensorimotor impairments, spatial memory deficits, and displayed seizures, phenotypes which were severe on the PDAPP background. These results suggest that while excess Abeta is functionally pathological, BACE1-mediated processing of APP and other substrates play a role in "normal" learning, memory and sensorimotor processes.
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Affiliation(s)
- Dione Kobayashi
- Rinat Neurosciences, 230 East Grand Avenue, South San Francisco, CA 94080, USA.
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65
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Minkeviciene R, Ihalainen J, Malm T, Matilainen O, Keksa-Goldsteine V, Goldsteins G, Iivonen H, Leguit N, Glennon J, Koistinaho J, Banerjee P, Tanila H. Age-related decrease in stimulated glutamate release and vesicular glutamate transporters in APP/PS1 transgenic and wild-type mice. J Neurochem 2008; 105:584-94. [DOI: 10.1111/j.1471-4159.2007.05147.x] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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66
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Suh J, Yoo SH, Kim MG, Jeong K, Ahn JY, Kim MS, Chae PS, Lee TY, Lee J, Lee J, Jang YA, Ko EH. Cleavage agents for soluble oligomers of amyloid beta peptides. Angew Chem Int Ed Engl 2008; 46:7064-7. [PMID: 17705324 DOI: 10.1002/anie.200702399] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Junghun Suh
- Department of Chemistry, Seoul National University, Seoul 151-747, Korea.
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67
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Cole SL, Vassar R. The Alzheimer's disease beta-secretase enzyme, BACE1. Mol Neurodegener 2007; 2:22. [PMID: 18005427 PMCID: PMC2211305 DOI: 10.1186/1750-1326-2-22] [Citation(s) in RCA: 343] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2007] [Accepted: 11/15/2007] [Indexed: 12/11/2022] Open
Abstract
The pathogenesis of Alzheimer's disease is highly complex. While several pathologies characterize this disease, amyloid plaques, composed of the β-amyloid peptide are hallmark neuropathological lesions in Alzheimer's disease brain. Indeed, a wealth of evidence suggests that β-amyloid is central to the pathophysiology of AD and is likely to play an early role in this intractable neurodegenerative disorder. The BACE1 enzyme is essential for the generation of β-amyloid. BACE1 knockout mice do not produce β-amyloid and are free from Alzheimer's associated pathologies including neuronal loss and certain memory deficits. The fact that BACE1 initiates the formation of β-amyloid, and the observation that BACE1 levels are elevated in this disease provide direct and compelling reasons to develop therapies directed at BACE1 inhibition thus reducing β-amyloid and its associated toxicities. However, new data indicates that complete abolishment of BACE1 may be associated with specific behavioral and physiological alterations. Recently a number of non-APP BACE1 substrates have been identified. It is plausible that failure to process certain BACE1 substrates may underlie some of the reported abnormalities in the BACE1-deficient mice. Here we review BACE1 biology, covering aspects ranging from the initial identification and characterization of this enzyme to recent data detailing the apparent dysregulation of BACE1 in Alzheimer's disease. We pay special attention to the putative function of BACE1 during healthy conditions and discuss in detail the relationship that exists between key risk factors for AD, such as vascular disease (and downstream cellular consequences), and the pathogenic alterations in BACE1 that are observed in the diseased state.
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Affiliation(s)
- Sarah L Cole
- Department of Cell and Molecular Biology, The Feinberg School of Medicine, Northwestern University, Chicago Avenue, Chicago, IL, USA.
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68
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69
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Schreurs BG, Smith-Bell CA, Darwish DS, Stankovic G, Sparks DL. High dietary cholesterol facilitates classical conditioning of the rabbit's nictitating membrane response. Nutr Neurosci 2007; 10:31-43. [PMID: 17539481 PMCID: PMC3115564 DOI: 10.1080/10284150701232034] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Studies have shown that modifying dietary cholesterol may improve learning and that serum cholesterol levels can be positively correlated with cognitive performance. Rabbits fed a 0, 0.5, 1 or 2% cholesterol diet for eight weeks and 0.12 ppm copper added to their drinking water received trace and then delay classical conditioning pairing tone with corneal air puff during which movement of the nictitating membrane (NM) across the eye was monitored. We found that the level of classical conditioning and conditioning-specific reflex modification (CRM) as well as the number of beta amyloid-labeled neurons in the cortex and hippocampus were a function of the concentration of cholesterol in the diet. The data provide support for the idea that dietary cholesterol may facilitate learning and memory.
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Affiliation(s)
- Bernard G Schreurs
- Department of Physiology and Pharmacology, West Virginia University, Blanchette Rockefeller Neurosciences Institute, Morgantown, WV, USA.
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70
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Abstract
In this issue of Molecular Pharmacology (p. 665), Pannacione et al. provide evidence of a role for the voltage-gated potassium channel alpha subunit Kv3.4 and its ancillary subunit MiRP2 in beta-amyloid (Abeta) peptide-mediated neuronal death. The MiRP2-Kv3.4 channel complex-previously found to be important in skeletal myocyte physiology-is now argued to be a molecular correlate of the transient outward potassium current up-regulated by Abeta peptide, considered a significant step in the etiology of Alzheimer's disease. The authors conclude that MiRP2 and Kv3.4 are up-regulated by Abeta peptide in a nuclear factor kappaB-dependent fashion at the transcriptional level, and the sea anemone toxin BDS-I is shown to protect against Abeta peptide-mediated cell death by specific blockade of Kv3.4-generated current. The findings lend weight to the premise that specific channels, such as MiRP2-Kv3.4, could hold promise as future therapeutic targets in Alzheimer's disease and potentially other neurodegenerative disorders.
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Affiliation(s)
- Eun Choi
- Greenberg Division of Cardiology, Department of Medicine, Cornell University, Weill Medical College, New York, NY 10021, USA
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71
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Trabace L, Kendrick KM, Castrignanò S, Colaianna M, De Giorgi A, Schiavone S, Lanni C, Cuomo V, Govoni S. Soluble amyloid beta1-42 reduces dopamine levels in rat prefrontal cortex: relationship to nitric oxide. Neuroscience 2007; 147:652-63. [PMID: 17560043 DOI: 10.1016/j.neuroscience.2007.04.056] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2007] [Revised: 04/03/2007] [Accepted: 04/05/2007] [Indexed: 11/16/2022]
Abstract
Several studies suggest a pivotal role of amyloid beta (Abeta)(1-42) and nitric oxide (NO) in the pathogenesis of Alzheimer's disease. NO also possess central neuromodulatory properties. To study the soluble Abeta(1-42) effects on dopamine concentrations in rat prefrontal cortex, microdialysis technique was used. We showed that i.c.v. injection or retrodialysis Abeta(1-42) administration reduced basal and K(+)-stimulated dopamine levels, measured 2 and 48 h after peptide administration. Immunofluorescent experiments revealed that after 48 h from i.c.v. injection Abeta(1-42) was no longer detectable in the ventricular space. We then evaluated the role of NO on Abeta(1-42)-induced reduction in dopamine concentrations. Subchronic L-arginine administration decreased basal dopamine levels, measured either 2 h after i.c.v. Abeta(1-42) or on day 2 post-injection, whereas subchronic 7-nitroindazole administration increased basal dopamine concentrations, measured 2 h after i.c.v. Abeta(1-42) injection, and decreased them when measured on day 2 post-Abeta(1-42)-injection. No dopaminergic response activity was observed after K(+) stimulation in all groups. These results suggest that the dopaminergic system seems to be acutely vulnerable to soluble Abeta(1-42) effects. Finally, the opposite role of NO occurring at different phases might be regarded as a possible link between Abeta(1-42)-induced effects and dopaminergic dysfunction.
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Affiliation(s)
- L Trabace
- Department of Biomedical Sciences, University of Foggia, Foggia, Italy.
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72
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Pannaccione A, Boscia F, Scorziello A, Adornetto A, Castaldo P, Sirabella R, Taglialatela M, Di Renzo GF, Annunziato L. Up-regulation and increased activity of KV3.4 channels and their accessory subunit MinK-related peptide 2 induced by amyloid peptide are involved in apoptotic neuronal death. Mol Pharmacol 2007; 72:665-73. [PMID: 17495071 DOI: 10.1124/mol.107.034868] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
The aim of the present study was to investigate whether K(V)3.4 channel subunits are involved in neuronal death induced by neurotoxic beta-amyloid peptides (Abeta). In particular, to test this hypothesis, three main questions were addressed: 1) whether the Abeta peptide can up-regulate both the transcription/translation and activity of K(V)3.4 channel subunit and its accessory subunit, MinK-related peptide 2 (MIRP2); 2) whether the increase in K(V)3.4 expression and activity can be mediated by the nuclear factor-kappaB (NF-kappaB) family of transcriptional factors; and 3) whether the specific inhibition of K(V)3.4 channel subunit reverts the Abeta peptide-induced neurodegeneration in hippocampal neurons and nerve growth factor (NGF)-differentiated PC-12 cells. We found that Abeta(1-42) treatment induced an increase in K(V)3.4 and MIRP2 transcripts and proteins, detected by reverse transcription-polymerase chain reaction and Western blot analysis, respectively, in NGF-differentiated PC-12 cells and hippocampal neurons. Patch-clamp experiments performed in whole-cell configuration revealed that the Abeta peptide caused an increase in I(A) current amplitude carried by K(V)3.4 channel subunits, as revealed by their specific blockade with blood depressing substance-I (BDS-I) in both hippocampal neurons and NGF-differentiated PC-12 cells. The inhibition of NF-kappaB nuclear translocation with the cell membrane-permeable peptide SN-50 prevented the increase in K(V)3.4 protein and transcript expression. In addition, the SN-50 peptide was able to block Abeta(1-42)-induced increase in K(V)3.4 K(+) currents and to prevent cell death caused by Abeta(1-42) exposure. Finally, BDS-I produced a similar neuroprotective effect by inhibiting the increase in K(V)3.4 expression. As a whole, our data indicate that K(V)3.4 channels could be a novel target for Alzheimer's disease pharmacological therapy.
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Affiliation(s)
- A Pannaccione
- Division of Pharmacology, Department of Neuroscience, School of Medicine, University of Naples Federico II, Naples, Italy
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73
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Schreurs BG, Smith-Bell CA, Darwish DS, Wang D, Burhans LB, Gonzales-Joekes J, Deci S, Stankovic G, Sparks DL. Cholesterol enhances classical conditioning of the rabbit heart rate response. Behav Brain Res 2007; 181:52-63. [PMID: 17466388 PMCID: PMC1942042 DOI: 10.1016/j.bbr.2007.03.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2006] [Revised: 02/05/2007] [Accepted: 03/21/2007] [Indexed: 01/19/2023]
Abstract
The cholesterol-fed rabbit is a model of atherosclerosis and has been proposed as an animal model of Alzheimer's disease. Feeding rabbits cholesterol has been shown to increase the number of beta amyloid immunoreactive neurons in the cortex. Addition of copper to the drinking water of cholesterol-fed rabbits can increase this number still further and may lead to plaque-like structures. Classical conditioning of the nictitating membrane response in cholesterol-fed rabbits is retarded in the presence of these plaque-like structures but may be facilitated in their absence. In a factorial design, rabbits fed 2% cholesterol or a normal diet (0% cholesterol) for 8 weeks with or without copper added to the drinking water were given trace classical conditioning using a tone and periorbital electrodermal stimulation to study the effects of cholesterol and copper on classical conditioning of heart rate and the nictitating membrane response. Cholesterol-fed rabbits showed significant facilitation of heart rate conditioning and conditioning-specific modification of heart rate relative to normal diet controls. Consistent with previous research, cholesterol had minimal effects on classical conditioning of the nictitating membrane response when periorbital electrodermal stimulation was used as the unconditioned stimulus. Immunohistochemical analysis showed a significant increase in the number of beta amyloid positive neurons in the cortex, hippocampus and amygdala of the cholesterol-fed rabbits. Supplementation of drinking water with copper increased the number of beta amyloid positive neurons in the cortex of cholesterol-fed rabbits but did not produce plaque-like structures or have a significant effect on heart rate conditioning. The data provide additional support for our finding that, in the absence of plaques, dietary cholesterol may facilitate learning and memory.
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Affiliation(s)
- Bernard G Schreurs
- Blanchette Rockefeller Neurosciences Institute and Department of Physiology and Pharmacology, West Virginia University, P.O. Box 9302, Morgantown, WV, United States.
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74
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Ohno M, Cole SL, Yasvoina M, Zhao J, Citron M, Berry R, Disterhoft JF, Vassar R. BACE1 gene deletion prevents neuron loss and memory deficits in 5XFAD APP/PS1 transgenic mice. Neurobiol Dis 2006; 26:134-45. [PMID: 17258906 PMCID: PMC1876698 DOI: 10.1016/j.nbd.2006.12.008] [Citation(s) in RCA: 228] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2006] [Revised: 11/29/2006] [Accepted: 12/06/2006] [Indexed: 10/23/2022] Open
Abstract
Evidence suggests that beta-amyloid (Abeta) peptide triggers a pathogenic cascade leading to neuronal loss in Alzheimer's disease (AD). However, the causal link between Abeta and neuron death in vivo remains unclear since most animal models fail to recapitulate the dramatic cell loss observed in AD. We have recently developed transgenic mice that overexpress human APP and PS1 with five familial AD mutations (5XFAD mice) and exhibit robust neuron death. Here, we demonstrate that genetic deletion of the beta-secretase (BACE1) not only abrogates Abeta generation and blocks amyloid deposition but also prevents neuron loss found in the cerebral cortex and subiculum, brain regions manifesting the most severe amyloidosis in 5XFAD mice. Importantly, BACE1 gene deletion also rescues memory deficits in 5XFAD mice. Our findings provide strong evidence that Abeta ultimately is responsible for neuron death in AD and validate the therapeutic potential of BACE1-inhibiting approaches for the treatment of AD.
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Affiliation(s)
- Masuo Ohno
- Department of Physiology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611-3008, USA.
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75
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Abstract
Alzheimer's disease is recognized post mortem by the presence of extracellular senile plaques, made primarily of aggregation of amyloid beta peptide (Abeta). This peptide has consequently been regarded as the principal toxic factor in the neurodegeneration of Alzheimer's disease. As such, intense research effort has been directed at determining its source, activity and fate, primarily with a view to preventing its formation or its biological activity, or promoting its degradation. Clearly, much progress has been made concerning its formation by proteolytic processing of the amyloid precursor protein, and its degradation by enzymes such as neprilysin and insulin degrading enzyme. The activities of Abeta, however, are numerous and yet to be fully elucidated. What is currently emerging from such studies is a diffuse but steadily growing body of data that suggests Abeta has important physiological functions and, further, that it should only be regarded as toxic when its production and degradation are imbalanced. Here, we review these data and suggest that physiological levels of Abeta have important physiological roles, and may even be crucial for neuronal cell survival. Thus, the view of Abeta being a purely toxic peptide requires re-evaluation.
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Affiliation(s)
- Hugh A Pearson
- Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK.
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76
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Yun SH, Gamkrelidze G, Stine WB, Sullivan PM, Pasternak JF, LaDu MJ, Trommer BL. Amyloid-beta1-42 reduces neuronal excitability in mouse dentate gyrus. Neurosci Lett 2006; 403:162-5. [PMID: 16765515 PMCID: PMC3752836 DOI: 10.1016/j.neulet.2006.04.065] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2006] [Revised: 04/10/2006] [Accepted: 04/24/2006] [Indexed: 11/17/2022]
Abstract
Amyloid-beta (Abeta) is causally implicated in Alzheimer's disease and neuroplasticity failure has acquired validity as a possible mechanism of early AD pathogenesis. We have previously demonstrated that oligomeric Abeta(1-42) inhibits LTP in the dentate gyrus of rat hippocampal slices. We now show, using whole cell recordings in hippocampal granule cells, that oligomeric Abeta(1-42) decreases neuronal excitability. In particular, Abeta(1-42) application was associated with a decrease in the number of action potentials fired in response to current injection, and with an increase in the amplitude of the afterhyperpolarization. Reduced excitability may underlie the Abeta-mediated impairment in neuroplasticity, and ultimately may contribute to the memory loss in Alzheimer disease.
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Affiliation(s)
- Sung Hwan Yun
- Departments of Pediatrics and Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, United States
- Department of Pediatrics, Division of Neurology, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston IL 60201, United States
- ENH Research Institute, 1001 University Place Evanston, IL 60202, United States
| | - Georgi Gamkrelidze
- Department of Physiology and Neuroscience, New York University School of Medicine, New York, NY 10016, United States
| | - W. Blaine Stine
- ENH Research Institute, 1001 University Place Evanston, IL 60202, United States
| | - Patrick M. Sullivan
- Department of Medicine, Division of Neurology, Duke University, Durham, NC 27710, United States
| | - Joseph F. Pasternak
- Departments of Pediatrics and Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, United States
- Department of Pediatrics, Division of Neurology, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston IL 60201, United States
- ENH Research Institute, 1001 University Place Evanston, IL 60202, United States
| | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois at Chicago, Chicago, IL 60612, United States
| | - Barbara L. Trommer
- Departments of Pediatrics and Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60614, United States
- Department of Pediatrics, Division of Neurology, Evanston Northwestern Healthcare, 2650 Ridge Avenue, Evanston IL 60201, United States
- ENH Research Institute, 1001 University Place Evanston, IL 60202, United States
- Corresponding author. Tel.: +1 847 570 2577; fax: +1 847 570 2073.
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