801
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Zhao WQ, De Felice FG, Fernandez S, Chen H, Lambert MP, Quon MJ, Krafft GA, Klein WL. Amyloid beta oligomers induce impairment of neuronal insulin receptors. FASEB J 2007; 22:246-60. [PMID: 17720802 DOI: 10.1096/fj.06-7703com] [Citation(s) in RCA: 419] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Recent studies have indicated an association between Alzheimer's disease (AD) and central nervous system (CNS) insulin resistance. However, the cellular mechanisms underlying the link between these two pathologies have not been elucidated. Here we show that signal transduction by neuronal insulin receptors (IR) is strikingly sensitive to disruption by soluble Abeta oligomers (also known as ADDLs). ADDLs are known to accumulate in AD brain and have recently been implicated as primary candidates for initiating deterioration of synapse function, composition, and structure. Using mature cultures of hippocampal neurons, a preferred model for studies of synaptic cell biology, we found that ADDLs caused a rapid and substantial loss of neuronal surface IRs specifically on dendrites bound by ADDLs. Removal of dendritic IRs was associated with increased receptor immunoreactivity in the cell body, indicating redistribution of the receptors. The neuronal response to insulin, measured by evoked IR tyrosine autophosphorylation, was greatly inhibited by ADDLs. Inhibition also was seen with added glutamate or potassium-induced depolarization. The effects on IR function were completely blocked by NMDA receptor antagonists, tetrodotoxin, and calcium chelator BAPTA-AM. Downstream from the IR, ADDLs induced a phosphorylation of Akt at serine473, a modification associated with neurodegenerative and insulin resistance diseases. These results identify novel factors that affect neuronal IR signaling and suggest that insulin resistance in AD brain is a response to ADDLs, which disrupt insulin signaling and may cause a brain-specific form of diabetes as part of an overall pathogenic impact on CNS synapses.
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Affiliation(s)
- Wei-Qin Zhao
- Department of Neurobiology and Physiology, Northwestern University, 2205 Tech Dr., Hogan 5-110, Evanston, IL 60280, USA.
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802
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Cauwe B, Van den Steen PE, Opdenakker G. The biochemical, biological, and pathological kaleidoscope of cell surface substrates processed by matrix metalloproteinases. Crit Rev Biochem Mol Biol 2007; 42:113-85. [PMID: 17562450 DOI: 10.1080/10409230701340019] [Citation(s) in RCA: 274] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Matrix metalloproteinases (MMPs) constitute a family of more than 20 endopeptidases. Identification of specific matrix and non-matrix components as MMP substrates showed that, aside from their initial role as extracellular matrix modifiers, MMPs play significant roles in highly complex processes such as the regulation of cell behavior, cell-cell communication, and tumor progression. Thanks to the comprehensive examination of the expanded MMP action radius, the initial view of proteases acting in the soluble phase has evolved into a kaleidoscope of proteolytic reactions connected to the cell surface. Important classes of cell surface molecules include adhesion molecules, mediators of apoptosis, receptors, chemokines, cytokines, growth factors, proteases, intercellular junction proteins, and structural molecules. Proteolysis of cell surface proteins by MMPs may have extremely diverse biological implications, ranging from maturation and activation, to inactivation or degradation of substrates. In this way, modification of membrane-associated proteins by MMPs is crucial for communication between cells and the extracellular milieu, and determines cell fate and the integrity of tissues. Hence, insights into the processing of cell surface proteins by MMPs and the concomitant effects on physiological processes as well as on disease onset and evolution, leads the way to innovative therapeutic approaches for cancer, as well as degenerative and inflammatory diseases.
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Affiliation(s)
- Bénédicte Cauwe
- Rega Institute for Medical Research, Laboratory of Immunobiology, University of Leuven, Leuven, Belgium
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803
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Yang X, Yang Y, Wu J, Zhu J. Stable Expression of a Novel Fusion Peptide of Thioredoxin-1 and ABAD-Inhibiting Peptide Protects PC12 Cells from Intracellular Amyloid-Beta. J Mol Neurosci 2007; 33:180-8. [DOI: 10.1007/s12031-007-0063-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2007] [Revised: 11/30/1999] [Accepted: 06/27/2007] [Indexed: 11/28/2022]
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804
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Parsons CG, Stöffler A, Danysz W. Memantine: a NMDA receptor antagonist that improves memory by restoration of homeostasis in the glutamatergic system--too little activation is bad, too much is even worse. Neuropharmacology 2007; 53:699-723. [PMID: 17904591 DOI: 10.1016/j.neuropharm.2007.07.013] [Citation(s) in RCA: 464] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 06/19/2007] [Accepted: 07/17/2007] [Indexed: 12/13/2022]
Abstract
The neurotransmitter glutamate activates several classes of metabotropic receptor and three major types of ionotropic receptor--alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA). The involvement of glutamate mediated neurotoxicity in the pathogenesis of Alzheimer's disease (AD) is finding increasing scientific acceptance. Central to this hypothesis is the assumption that glutamate receptors, in particular of the NMDA type, are overactivated in a tonic rather than a phasic manner. Such continuous, mild, chronic activation ultimately leads to neuronal damage/death. Additionally, impairment of synaptic plasticity (learning) may result not only from neuronal damage per se but may also be a direct consequence of this continuous, non-contingent NMDA receptor activation. Complete NMDA receptor blockade has also been shown to impair neuronal plasticity, thus, both hypo- and hyperactivity of the glutamatergic system leads to dysfunction. Memantine received marketing authorization from the EMEA (European Medicines Agency) for the treatment of moderate to severe AD in Europe and was subsequently also approved by the FDA (Food and Drug Administration) for use in the same indication in the USA. Memantine is a moderate affinity, uncompetitive NMDA receptor antagonist with strong voltage-dependency and fast kinetics. This review summarizes existing hypotheses on the mechanism of action (MOA) of memantine in an attempt to understand how the accepted interaction with NMDA receptors could allow memantine to provide both neuroprotection and reverse deficits in learning/memory by the same MOA.
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Affiliation(s)
- Chris G Parsons
- Merz Pharmaceuticals, Eckenheimer Landstrasse 100, 60318 Frankfurt am Main, Germany
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805
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Farris W, Schütz SG, Cirrito JR, Shankar GM, Sun X, George A, Leissring MA, Walsh DM, Qiu WQ, Holtzman DM, Selkoe DJ. Loss of neprilysin function promotes amyloid plaque formation and causes cerebral amyloid angiopathy. THE AMERICAN JOURNAL OF PATHOLOGY 2007; 171:241-51. [PMID: 17591969 PMCID: PMC1941603 DOI: 10.2353/ajpath.2007.070105] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cerebral deposition of the amyloid beta protein (Abeta), an invariant feature of Alzheimer's disease, reflects an imbalance between the rates of Abeta production and clearance. The causes of Abeta elevation in the common late-onset form of Alzheimer's disease (LOAD) are largely unknown. There is evidence that the Abeta-degrading protease neprilysin (NEP) is down-regulated in normal aging and LOAD. We asked whether a decrease in endogenous NEP levels can prolong the half-life of Abeta in vivo and promote development of the classic amyloid neuropathology of Alzheimer's disease. We examined the brains and plasma of young and old mice expressing relatively low levels of human amyloid precursor protein and having one or both NEP genes silenced. NEP loss of function 1) elevated whole-brain and plasma levels of human Abeta(40) and Abeta(42), 2) prolonged the half-life of soluble Abeta in brain interstitial fluid of awake animals, 3) raised the concentration of Abeta dimers, 4) markedly increased hippocampal amyloid plaque burden, and 5) led to the development of amyloid angiopathy. A approximately 50% reduction in NEP levels, similar to that reported in some LOAD brains, was sufficient to increase amyloid neuropathology. These findings demonstrate an important role for proteolysis in determining the levels of Abeta and Abeta-associated neuropathology in vivo and support the hypothesis that primary defects in Abeta clearance can cause or contribute to LOAD pathogenesis.
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Affiliation(s)
- Wesley Farris
- Center for Neurologic Diseases, Department of Neurology, Harvard Institutes of Medicine, Room 730, Boston, MA 02115, USA.
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806
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Cacquevel M, Launay S, Castel H, Benchenane K, Chéenne S, Buée L, Moons L, Delacourte A, Carmeliet P, Vivien D. Ageing and amyloid-beta peptide deposition contribute to an impaired brain tissue plasminogen activator activity by different mechanisms. Neurobiol Dis 2007; 27:164-73. [PMID: 17566751 DOI: 10.1016/j.nbd.2007.04.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2006] [Revised: 02/23/2007] [Accepted: 04/07/2007] [Indexed: 10/23/2022] Open
Abstract
Alzheimer's disease (AD) is the most common form of neurodegenerative disorder in the ageing population. It is characterized by the cerebral accumulation of toxic amyloid-beta peptide assemblies (Abeta). The serine protease plasmin, which is generated from the inactive zymogen plasminogen through its proteolytic cleavage by tissue- (tPA) or urokinase-type plasminogen activator, has been implicated in the catabolism of Abeta peptides. In this report, we studied the regulation of tPA activity in vivo during ageing in normal mice and in a mouse model of AD characterized by an exacerbated endogenous Abeta accumulation. We observed that cerebral tPA activity was decreased during ageing in normal mice and that this effect was worsened in mice overproducing Abeta peptides. These phenomena result, respectively, from a decrease in tPA expression and from an increase in the production of one of the tPA inhibitors, the plasminogen activator inhibitor type 1 (PAI-1). A similar study in sporadic AD and age-matched control brain tissues revealed that the tPA proteolytic activity was negatively correlated to Abeta peptides levels supporting the data observed in mice. Altogether, our data support a model in which amyloid deposition induces a decrease in tPA activity through the overproduction of PAI-1 by activated glial cells.
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807
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Okada T, Wakabayashi M, Ikeda K, Matsuzaki K. Formation of Toxic Fibrils of Alzheimer’s Amyloid β-Protein-(1–40) by Monosialoganglioside GM1, a Neuronal Membrane Component. J Mol Biol 2007; 371:481-9. [PMID: 17582434 DOI: 10.1016/j.jmb.2007.05.069] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Revised: 05/08/2007] [Accepted: 05/21/2007] [Indexed: 10/23/2022]
Abstract
A pathological hallmark of Alzheimer's disease (AD) is the deposition of amyloid beta-protein (Abeta) in fibrillar form on neuronal cells. However, the role of Abeta fibrils in neuronal dysfunction is highly controversial. This study demonstrates that monosialoganglioside GM1 (GM1) released from damaged neurons catalyzes the formation of Abeta fibrils, the toxicity and the cell affinity of which are much stronger than those of Abeta fibrils formed in phosphate-buffered saline. Abeta-(1-40) was incubated with equimolar GM1 at 37 degrees C. After a lag period of 6-12 h, amyloid fibrils were formed, as confirmed by circular dichroism, thioflavin-T fluorescence, size-exclusion chromatography, and transmission electron microscopy. The fibrils showed significant cytotoxicity against PC12 cells differentiated with nerve growth factor. Trisialoganglioside GT1b also facilitated the fibrillization, although the effect was weaker than that of GM1. Our study suggests an exacerbation mechanism of AD and an importance of polymorphisms in Abeta fibrils during the pathogenesis of the disease.
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Affiliation(s)
- Takuma Okada
- Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto 606-8501, Japan
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808
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Dewachter I, Filipkowski RK, Priller C, Ris L, Neyton J, Croes S, Terwel D, Gysemans M, Devijver H, Borghgraef P, Godaux E, Kaczmarek L, Herms J, Van Leuven F. Deregulation of NMDA-receptor function and down-stream signaling in APP[V717I] transgenic mice. Neurobiol Aging 2007; 30:241-56. [PMID: 17673336 DOI: 10.1016/j.neurobiolaging.2007.06.011] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Revised: 06/13/2007] [Accepted: 06/15/2007] [Indexed: 10/23/2022]
Abstract
Evidence is accumulating for a role for amyloid peptides in impaired synaptic plasticity and cognition, while the underlying mechanisms remain unclear. We here analyzed the effects of amyloid peptides on NMDA-receptor function in vitro and in vivo. A synthetic amyloid peptide preparation containing monomeric and oligomeric A beta (1-42) peptides was used and demonstrated to bind to synapses expressing NMDA-receptors in cultured hippocampal and cortical neurons. Pre-incubation of primary neuronal cultures with A beta peptides significantly inhibited NMDA-receptor function, albeit not by a direct pharmacological inhibition of NMDA-receptors, since acute application of A beta peptides did not change NMDA-receptor currents in autaptic hippocampal cultures nor in xenopus oocytes expressing recombinant NMDA-receptors. Pre-incubation of primary neuronal cultures with A beta peptides however decreased NR2B-immunoreactive synaptic spines and surface expression of NR2B containing NMDA-receptors. Furthermore, we extended these findings for the first time in vivo, demonstrating decreased concentrations of NMDA-receptor subunit NR2B and PSD-95 as well as activated alpha-CaMKII in postsynaptic density preparations of APP[V717I] transgenic mice. This was associated with impaired NMDA-dependent LTP and decreased NMDA- and AMPA-receptor currents in hippocampal CA1 region in APP[V717I] transgenic mice. In addition, induction of c-Fos following cued and contextual fear conditioning was significantly impaired in the basolateral amygdala and hippocampus of APP[V717I] transgenic mice. Our data demonstrate defects in NMDA-receptor function and learning dependent signaling cascades in vivo in APP[V717I] transgenic mice and point to decreased surface expression of NMDA-receptors as a mechanism involved in early synaptic defects in APP[V717I] transgenic mice in vivo.
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Affiliation(s)
- I Dewachter
- Experimental Genetics Group, LEGT_EGG, K.U.Leuven, Campus Gasthuisberg ON1-06.602, 3000 Leuven, Belgium
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809
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Galvan V, Banwait S, Spilman P, Gorostiza OF, Peel A, Crippen D, Sidhu G, Ichijo H, Bredesen DE. Interaction of ASK1 and the beta-amyloid precursor protein in a stress-signaling complex. Neurobiol Dis 2007; 28:65-75. [PMID: 17719230 PMCID: PMC2084074 DOI: 10.1016/j.nbd.2007.06.017] [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] [Received: 08/10/2006] [Revised: 06/05/2007] [Accepted: 06/14/2007] [Indexed: 11/21/2022] Open
Abstract
The amyloid precursor protein (APP) is a type I transmembrane protein translocated to neuronal terminals, whose function is still unknown. The C-terminus of APP mediates its interaction with cellular adaptor and signaling proteins, some of which signal to the stress-activated protein kinase (SAPK) pathway. Here we show that ASK1, a MAPKKK that activates two SAPKs, c-Jun N-terminal-kinase (JNK) and p38, is present in a complex containing APP, phospho-MKK6, JIP1 and JNK1. In primary neurons deprived of growth factors, as well as in brains of (FAD)APP-transgenic mice, ASK1 was upregulated in neuronal projections, where it interacted with APP. In non-transgenic brains, ASK1 and APP associated mainly in the ER. Our results indicate that recruitment of ASK1 to stress-signaling complexes assembled with APP may be triggered and enhanced by cellular stress. Thus, ASK1 may be the apical MAPKKK in a signaling complex assembled with APP as a response to stress.
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Affiliation(s)
- Veronica Galvan
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Surita Banwait
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Patricia Spilman
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | | | - Alyson Peel
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Danielle Crippen
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Gurleen Sidhu
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
| | - Hidenori Ichijo
- Laboratory of Cell Signaling, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Dale E. Bredesen
- Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945, USA
- To whom correspondence should be addressed, at The Buck Institute for Age Research, 8001 Redwood Blvd., Novato, CA 94945; Phone: 415-209-2090; fax: 415-209-2230; e-mail
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810
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Abstract
Phenserine, a derivative of physostigmine, was first described as an inhibitor of acetylcholinesterase (AChE) and was shown to improve cognition in various experimental paradigms in rodents and dogs. It was clinically tested for Alzheimer's disease, with moderate success in initial Phase II studies. Phenserine deserves attention for an additional quality of action: in addition to inhibiting AChE, it modulates the amount of beta-amyloid precursor protein (APP) in neuronal cell culture by reducing APP translation. This effect probably involves interaction of phenserine with a regulatory element in the 5'-untranslated region of the APP gene that controls APP expression. Phenserine apparently reduces translational efficiency of APP mRNA into protein, a process that may involve an interaction with iron and/or an iron-responsive element. As a consequence, phenserine reduces beta-amyloid peptide (Abeta) formation in vitro and in vivo. Phenserine is also unique because of differing actions of its enantiomers: (-)-phenserine is the active enantiomer for inhibition of AChE, whereas (+)-phenserine ('posiphen') has weak activity as an AChE inhibitor and can be dosed much higher. Both enantiomers are equipotent in downregulating APP expression. (+)-Posiphen may be a promising drug, either alone or in combination with (-)-phenserine, to attenuate the progression of Alzheimer's disease.
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Affiliation(s)
- Jochen Klein
- University of Frankfurt College of Pharmacy, Biocenter N260, Frankfurt, Germany.
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811
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Vega GL, Weiner MF. Plasma 24S Hydroxycholesterol Response to Statins in Alzheimer’s Disease Patients: Effects of Gender, CYP46, and ApoE Polymorphisms. J Mol Neurosci 2007; 33:51-5. [PMID: 17901546 DOI: 10.1007/s12031-007-0040-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/1999] [Revised: 11/30/1999] [Accepted: 11/30/1999] [Indexed: 11/29/2022]
Abstract
A number of epidemiologic studies suggest an association between plasma total cholesterol and risk for Alzheimer's disease (AD). Additionally, it has been suggested that treatment with statins, drugs that block cholesterol biosynthesis, lower the incidence and prevalence of AD and of vascular dementia. This review provides an overview of cholesterol transport within the central nervous system and the impact of statins on brain cholesterol metabolism in subjects with AD. Brain cholesterol is converted to 24-S-hydroxycholesterol, a reaction catalyzed by CYP46. The oxysterol traverses the blood-brain barrier and is transported to the liver by plasma lipoproteins. The levels of 24-S-hydroxy-cholesterol are a reflection of brain cholesterol turnover. Subjects with AD reportedly have high levels of the oxysterol possibly reflecting neuronal death with release of cell membrane cholesterol. We show gender dimorphism in plasma levels of 24-S-hydroxycholesterol in subjects with AD and significant reductions in plasma levels of the oxysterol during treatment with standard doses of statins (lovastatin, simvastatin, and pravastatin). Polymorphisms of apolipoprotein E and CYP46 do not influence the effect of statins on plasma levels of 24-S-hydroxycholesterol. There were no untoward effects of the standard doses of statin for the duration of treatment. Statins are currently in trial to determine their effect on the course of AD.
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Affiliation(s)
- Gloria Lena Vega
- The Nutrition and Metabolism Laboratory, Metabolic Unit, Veterans Affairs Medical Center, Dallas, TX 75390, USA.
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812
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Murphy MP, Beckett TL, Ding Q, Patel E, Markesbery WR, St Clair DK, LeVine H, Keller JN. Abeta solubility and deposition during AD progression and in APPxPS-1 knock-in mice. Neurobiol Dis 2007; 27:301-11. [PMID: 17651976 DOI: 10.1016/j.nbd.2007.06.002] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Revised: 05/14/2007] [Accepted: 06/04/2007] [Indexed: 01/02/2023] Open
Abstract
Amnestic mild cognitive impairment (MCI) appears to be a very early stage of Alzheimer's disease (AD). The amyloid-beta peptide (Abeta) is believed to be a possible substrate for AD, but little is currently known about Abeta alterations in MCI and how these changes compare to later stages of disease. In the present study Abeta was differentially extracted from the brains of age-matched control, MCI, and AD cases and compared with plaque counts. For comparison, APPxPS-1 knock-in mice were processed in parallel. We observed that Abeta42 was significantly elevated in MCI subjects, even though there was no significant alteration in the total amount of Abeta. Relative Abeta solubility within the different extractable pools was identical between AD and MCI subjects, with both significantly altered relative to controls. Temporal analysis of Abeta levels and solubility in a knock-in mouse model of Abeta pathogenesis recapitulated many of the salient features observed in AD. Characterization of the SDS fraction showed some similarities between aged knock-in mice and AD subjects. These data suggest that distinct changes in Abeta occur throughout the progression of AD, and that elevations in Abeta42 occur at an early, clinically defined stage.
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Affiliation(s)
- M Paul Murphy
- Department of Molecular and Cellular Biochemistry, Sanders-Brown Center on Aging, University of Kentucky, Lexington, Kentucky 40536-0230, USA.
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813
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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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814
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Cheng IH, Scearce-Levie K, Legleiter J, Palop JJ, Gerstein H, Bien-Ly N, Puoliväli J, Lesné S, Ashe KH, Muchowski PJ, Mucke L. Accelerating amyloid-beta fibrillization reduces oligomer levels and functional deficits in Alzheimer disease mouse models. J Biol Chem 2007; 282:23818-28. [PMID: 17548355 DOI: 10.1074/jbc.m701078200] [Citation(s) in RCA: 322] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many proteins suspected of causing neurodegenerative diseases exist in diverse assembly states. For most, it is unclear whether shifts from one state to another would be helpful or harmful. We used mutagenesis to change the assembly state of Alzheimer disease (AD)-associated amyloid-beta (Abeta) peptides. In vitro, the "Arctic" mutation (AbetaE22G) accelerated Abeta fibrillization but decreased the abundance of nonfibrillar Abeta assemblies, compared with wild-type Abeta. In human amyloid precursor protein (hAPP) transgenic mice carrying mutations adjacent to Abeta that increase Abeta production, addition of the Arctic mutation markedly enhanced the formation of neuritic amyloid plaques but reduced the relative abundance of a specific nonfibrillar Abeta assembly (Abeta*56). Mice overexpressing Arctic mutant or wild-type Abeta had similar behavioral and neuronal deficits when they were matched for Abeta*56 levels but had vastly different plaque loads. Thus, Abeta*56 is a likelier determinant of functional deficits in hAPP mice than fibrillar Abeta deposits. Therapeutic interventions that reduce Abeta fibrils at the cost of augmenting nonfibrillar Abeta assemblies could be harmful.
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Affiliation(s)
- Irene H Cheng
- Gladstone Institute of Neurological Disease, San Francisco, California 94158, USA
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815
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Lezoualc'h F. 5-HT4 receptor and Alzheimer's disease: The amyloid connection. Exp Neurol 2007; 205:325-9. [PMID: 17346704 DOI: 10.1016/j.expneurol.2007.02.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 01/30/2007] [Accepted: 02/01/2007] [Indexed: 11/21/2022]
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816
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Arancio O, Chao MV. Neurotrophins, synaptic plasticity and dementia. Curr Opin Neurobiol 2007; 17:325-30. [PMID: 17419049 DOI: 10.1016/j.conb.2007.03.013] [Citation(s) in RCA: 146] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Accepted: 03/28/2007] [Indexed: 01/08/2023]
Abstract
The growing realization that neurotrophins, such as brain-derived neurotrophic factor (BDNF), are crucial in modulating synaptic plasticity has broadened the spectrum of their trophic actions. At the same time, it has become clear that Abeta peptides derived from amyloid precursor protein (APP) have dramatic effects on synaptic transmission before the onset of the neurodegenerative disease. Because neurotrophins and Abeta are responsible for affecting both synaptic and cognitive function, it is likely that their mechanisms of action will be related and might even intersect. This review highlights several recent findings that suggest trophic factors and APP use similar pathways to control neuronal activity.
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Affiliation(s)
- Ottavio Arancio
- Department of Pathology and Taub Institute, Columbia University College of Physicians and Surgeons, 630 W168th Street, New York, NY 10032, USA
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817
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Small DH, Maksel D, Kerr ML, Ng J, Hou X, Chu C, Mehrani H, Unabia S, Azari MF, Loiacono R, Aguilar MI, Chebib M. The ?-amyloid protein of Alzheimer?s disease binds to membrane lipids but does not bind to the ?7 nicotinic acetylcholine receptor. J Neurochem 2007; 101:1527-38. [PMID: 17286584 DOI: 10.1111/j.1471-4159.2006.04444.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Accumulation of the amyloid protein (Abeta) in the brain is an important step in the pathogenesis of Alzheimer's disease. However, the mechanism by which Abeta exerts its neurotoxic effect is largely unknown. It has been suggested that the peptide can bind to the alpha7 nicotinic acetylcholine receptor (alpha7nAChR). In this study, we examined the binding of Abeta1-42 to endogenous and recombinantly expressed alpha7nAChRs. Abeta1-42 did neither inhibit the specific binding of alpha7nAChR ligands to rat brain homogenate or slice preparations, nor did it influence the activity of alpha7nAChRs expressed in Xenopus oocytes. Similarly, Abeta1-42 did not compete for alpha-bungarotoxin-binding sites on SH-SY5Y cells stably expressing alpha7nAChRs. The effect of the Abeta1-42 on tau phosphorylation was also examined. Although Abeta1-42 altered tau phosphorylation in alpha7nAChR-transfected SH-SY5Y cells, the effect of the peptide was unrelated to alpha7nAChR expression or activity. Binding studies using surface plasmon resonance indicated that the majority of the Abeta bound to membrane lipid, rather than to a protein component. Fluorescence anisotropy experiments indicated that Abeta may disrupt membrane lipid structure or fluidity. We conclude that the effects of Abeta are unlikely to be mediated by direct binding to the alpha7nAChR. Instead, we speculate that Abeta may exert its effects by altering the packing of lipids within the plasma membrane, which could, in turn, influence the function of a variety of receptors and channels on the cell surface.
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Affiliation(s)
- David H Small
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria, Australia.
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818
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González I, Arévalo-Serrano J, Sanz-Anquela JM, Gonzalo-Ruiz A. Effects of beta-amyloid protein on M1 and M2 subtypes of muscarinic acetylcholine receptors in the medial septum-diagonal band complex of the rat: relationship with cholinergic, GABAergic, and calcium-binding protein perikarya. Acta Neuropathol 2007; 113:637-51. [PMID: 17294199 DOI: 10.1007/s00401-007-0201-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2006] [Revised: 01/18/2007] [Accepted: 01/18/2007] [Indexed: 10/23/2022]
Abstract
Cortical cholinergic dysfunction has been correlated with the expression and processing of beta-amyloid precursor protein. However, it remains unclear as to how cholinergic dysfunction and beta-amyloid (Abeta) formation and deposition might be related to one another. Since the M1- and M2 subtypes of muscarinic acetylcholine receptors (mAChRs) are considered key molecules that transduce the cholinergic message, the purpose of the present study was to assess the effects of the injected Abeta peptide on the number of M1mAchR- and M2mAChR-immunoreactive cells in the medial septum-diagonal band (MS-nDBB) complex of the rat. Injections of Abeta protein into the retrosplenial cortex resulted in a decrease in M1mAChR and M2mAChR immunoreactivity in the MS-nDBB complex. Quantitative analysis revealed a significant reduction in the number of M1mAChR- and M2mAChR-immunoreactive cells in the medial septum nucleus (MS) and in the horizontal nucleus of the diagonal band of Broca (HDB) as compared to the corresponding hemisphere in control animals and with that seen in the contralateral hemisphere, which corresponds to the PBS-injected side. Co-localization studies showed that the M1mAChR protein is localized in GABA-immunoreactive cells of the MS-nDBB complex, in particular those of the MS nucleus, while M2mAChR protein is localized in both the cholinergic and GABAergic cells. Moreover, GABAergic cells containing M2mAChR are mainly localized in the MS nucleus, while cholinergic cells containing M2mAChR are localized in the MS and the HDB nuclei. Our findings suggest that Abeta induces a reduction in M1mAChR- and M2mAChR-containing cells, which may contribute to impairments of cholinergic and GABAergic transmission in the MS-nDBB complex.
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Affiliation(s)
- Iván González
- Laboratory of Neuroanatomy, Institute of Neuroscience of Castilla and León, University of Valladolid, Campus de los Pajaritos de Soria, 42004 Soria, Spain
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819
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Medeiros R, Prediger RDS, Passos GF, Pandolfo P, Duarte FS, Franco JL, Dafre AL, Di Giunta G, Figueiredo CP, Takahashi RN, Campos MM, Calixto JB. Connecting TNF-alpha signaling pathways to iNOS expression in a mouse model of Alzheimer's disease: relevance for the behavioral and synaptic deficits induced by amyloid beta protein. J Neurosci 2007; 27:5394-404. [PMID: 17507561 PMCID: PMC6672347 DOI: 10.1523/jneurosci.5047-06.2007] [Citation(s) in RCA: 218] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Increased brain deposition of amyloid beta protein (Abeta) and cognitive deficits are classical signals of Alzheimer's disease (AD) that have been highly associated with inflammatory alterations. The present work was designed to determine the correlation between tumor necrosis factor-alpha (TNF-alpha)-related signaling pathways and inducible nitric oxide synthase (iNOS) expression in a mouse model of AD, by means of both in vivo and in vitro approaches. The intracerebroventricular injection of Abeta(1-40) in mice resulted in marked deficits of learning and memory, according to assessment in the water maze paradigm. This cognition impairment seems to be related to synapse dysfunction and glial cell activation. The pharmacological blockage of either TNF-alpha or iNOS reduced the cognitive deficit evoked by Abeta(1-40) in mice. Similar results were obtained in TNF-alpha receptor 1 and iNOS knock-out mice. Abeta(1-40) administration induced an increase in TNF-alpha expression and oxidative alterations in prefrontal cortex and hippocampus. Likewise, Abeta(1-40) led to activation of both JNK (c-Jun-NH2-terminal kinase)/c-Jun and nuclear factor-kappaB, resulting in iNOS upregulation in both brain structures. The anti-TNF-alpha antibody reduced all of the molecular and biochemical alterations promoted by Abeta(1-40). These results provide new insights in mouse models of AD, revealing TNF-alpha and iNOS as central mediators of Abeta action. These pathways might be targeted for AD drug development.
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Affiliation(s)
| | | | | | | | | | | | - Alcir L. Dafre
- Ciências Fisiológicas, Centro de Ciências Biológicas, and
| | - Gabriella Di Giunta
- Departamento de Anatomia Patológica, Hospital Universitário–Universidade Federal de Santa Catarina, 88049-900, Florianópolis, Santa Catarina, Brazil, and
| | - Cláudia P. Figueiredo
- Departamento de Anatomia Patológica, Hospital Universitário–Universidade Federal de Santa Catarina, 88049-900, Florianópolis, Santa Catarina, Brazil, and
| | | | - Maria M. Campos
- Faculdade de Odontologia, Pontifícia Universidade Católica do Rio Grande do Sul 90619-900, Rio Grande do Sul, Brazil
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820
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Simonsen AH, Hansson SF, Ruetschi U, McGuire J, Podust VN, Davies HA, Mehta P, Waldemar G, Zetterberg H, Andreasen N, Wallin A, Blennow K. Amyloid beta1-40 quantification in CSF: comparison between chromatographic and immunochemical methods. Dement Geriatr Cogn Disord 2007; 23:246-50. [PMID: 17310122 DOI: 10.1159/000100020] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/28/2006] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND/AIMS Amyloid beta (Abeta) is the principal component of senile plaques, one of the hallmarks of Alzheimer's disease (AD). Evidence is accumulating that soluble aggregates (oligomers) of Abeta are important in the pathogenesis of AD. METHODS We compared three different methods for quantification of the 40 amino acid form of Abeta (Abeta40) in CSF, two based on antibodies [ELISA and surface-enhanced laser desorption/ionization-time of flight (SELDI-TOF) with antibody-coated arrays] and one based on direct binding of proteins to a protein array [SELDI-TOF and immobilized metal affinity [copper] (IMAC30)]. RESULTS CSF Abeta40 concentration was only found to be significantly elevated in AD (127% of control levels; p=0.0095) using SELDI-TOF with IMAC30 arrays. CONCLUSIONS These data suggest that the measured Abeta level in CSF may differ depending on whether antibody-based methods are used or not, possibly caused by epitope masking due to Abeta oligomerization or to binding of Abeta to carrier proteins.
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Affiliation(s)
- A H Simonsen
- Biomarker Discovery Center Facility, Ciphergen, Copenhagen, Denmark.
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821
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Muhs A, Hickman DT, Pihlgren M, Chuard N, Giriens V, Meerschman C, van der Auwera I, van Leuven F, Sugawara M, Weingertner MC, Bechinger B, Greferath R, Kolonko N, Nagel-Steger L, Riesner D, Brady RO, Pfeifer A, Nicolau C. Liposomal vaccines with conformation-specific amyloid peptide antigens define immune response and efficacy in APP transgenic mice. Proc Natl Acad Sci U S A 2007; 104:9810-5. [PMID: 17517595 PMCID: PMC1887581 DOI: 10.1073/pnas.0703137104] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We investigated the therapeutic effects of two different versions of Abeta(1-15 (16)) liposome-based vaccines. Inoculation of APP-V717IxPS-1 (APPxPS-1) double-transgenic mice with tetra-palmitoylated amyloid 1-15 peptide (palmAbeta(1-15)), or with amyloid 1-16 peptide (PEG-Abeta(1-16)) linked to a polyethyleneglycol spacer at each end, and embedded within a liposome membrane, elicited fast immune responses with identical binding epitopes. PalmAbeta(1-15) liposomal vaccine elicited an immune response that restored the memory defect of the mice, whereas that of PEG-Abeta(1-16) had no such effect. Immunoglobulins that were generated were predominantly of the IgG class with palmAbeta(1-15), whereas those elicited by PEG-Abeta(1-16) were primarily of the IgM class. The IgG subclasses of the antibodies generated by both vaccines were mostly IgG2b indicating noninflammatory Th2 isotype. CD and NMR revealed predominantly beta-sheet conformation of palmAbeta(1-15) and random coil of PEG-Abeta(1-16). We conclude that the association with liposomes induced a variation of the immunogenic structures and thereby different immunogenicities. This finding supports the hypothesis that Alzheimer's disease is a "conformational" disease, implying that antibodies against amyloid sequences in the beta-sheet conformation are preferred as potential therapeutic agents.
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Affiliation(s)
- Andreas Muhs
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - David T. Hickman
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Maria Pihlgren
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Nathalie Chuard
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Valérie Giriens
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Carine Meerschman
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | | | - Fred van Leuven
- Experimental Genetics Group, KULeuven, B-3000 Leuven, Belgium
| | - Masae Sugawara
- Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur, F-67083 Strasbourg, France
| | | | - Burkhard Bechinger
- Institut de Science et d'Ingénierie Supramoléculaires, Université Louis Pasteur, F-67083 Strasbourg, France
| | - Ruth Greferath
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Nadine Kolonko
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Luitgard Nagel-Steger
- Institut für Biophysikalische Chemie, Heinrich-Heine Universität, 40225 Düsseldorf, Germany
| | - Detlev Riesner
- Institut für Biophysikalische Chemie, Heinrich-Heine Universität, 40225 Düsseldorf, Germany
| | - Roscoe O. Brady
- Developmental and Metabolic Neurology Branch, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892; and
- **To whom correspondence may be addressed. E-mail: or
| | - Andrea Pfeifer
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - Claude Nicolau
- *AC Immune, PSE-B, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Friedman School of Nutrition Science and Policy, Tufts University, Boston, MA 02111
- **To whom correspondence may be addressed. E-mail: or
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822
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Spasic D, Raemaekers T, Dillen K, Declerck I, Baert V, Serneels L, Füllekrug J, Annaert W. Rer1p competes with APH-1 for binding to nicastrin and regulates gamma-secretase complex assembly in the early secretory pathway. ACTA ACUST UNITED AC 2007; 176:629-40. [PMID: 17325205 PMCID: PMC2064021 DOI: 10.1083/jcb.200609180] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
The γ-secretase complex, consisting of presenilin, nicastrin, presenilin enhancer-2 (PEN-2), and anterior pharynx defective-1 (APH-1) cleaves type I integral membrane proteins like amyloid precursor protein and Notch in a process of regulated intramembrane proteolysis. The regulatory mechanisms governing the multistep assembly of this “proteasome of the membrane” are unknown. We characterize a new interaction partner of nicastrin, the retrieval receptor Rer1p. Rer1p binds preferentially immature nicastrin via polar residues within its transmembrane domain that are also critical for interaction with APH-1. Absence of APH-1 substantially increased binding of nicastrin to Rer1p, demonstrating the competitive nature of these interactions. Moreover, Rer1p expression levels control the formation of γ-secretase subcomplexes and, concomitantly, total cellular γ-secretase activity. We identify Rer1p as a novel limiting factor that negatively regulates γ-secretase complex assembly by competing with APH-1 during active recycling between the endoplasmic reticulum (ER) and Golgi. We conclude that total cellular γ-secretase activity is restrained by a secondary ER control system that provides a potential therapeutic value.
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Affiliation(s)
- Dragana Spasic
- Laboratory for Membrane Trafficking, Center for Human Genetics, Katholieke Universiteit Leuven/Vlaams Instituut voor Biotechnologie, Gasthuisberg, Leuven, B-3000 Leuven, Belgium
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823
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Youssef I, Florent-Béchard S, Malaplate-Armand C, Koziel V, Bihain B, Olivier JL, Leininger-Muller B, Kriem B, Oster T, Pillot T. N-truncated amyloid-beta oligomers induce learning impairment and neuronal apoptosis. Neurobiol Aging 2007; 29:1319-33. [PMID: 17459527 DOI: 10.1016/j.neurobiolaging.2007.03.005] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2006] [Revised: 02/23/2007] [Accepted: 03/04/2007] [Indexed: 01/09/2023]
Abstract
N-terminal-truncated forms of amyloid-beta (A beta) peptide have been recently suggested to play a pivotal role early in Alzheimer's disease (AD). Among them, A beta 3(pE)-42 peptide, starting with pyroglutamyl at residue Glu-3, is considered as the predominant A beta species in AD plaques and pre-amyloid lesions. Its abundance is reported to be directly proportional to the severity of the clinical phenotype. The present study investigates the effects of soluble oligomeric A beta 3(pE)-42 after intracerebroventricular injection on mice learning ability and the molecular mechanisms of its in vitro neurotoxicity. Mice injected with soluble A beta 3(pE)-42 or A beta(l-42) displayed impaired spatial working memory and delayed memory acquisition in Y-maze and Morris water maze tests, while those injected with soluble A beta(42-1) showed no effect. These cognitive alterations were associated with free radical overproduction in the hippocampus and olfactory bulbs, but not in the cerebral cortex or cerebellum. In vitro, A beta 3(pE)-42 oligomers induced a redox-sensitive neuronal apoptosis involving caspase activation and an arachidonic acid-dependent pro-inflammatory pathway. These data suggest that A beta 3(pE)-42 could mediate the neurodegenerative process and subsequent cognitive alteration occurring in preclinical AD stages.
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Affiliation(s)
- Ihsen Youssef
- Lipidomix, JE 2482, INPL, Laboratoire de Médecine et Thérapeutique Moléculaire, 15 rue du Bois de la Champelle, 54505 Vandoeuvre-lès-Nancy, France
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824
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Fan R, Xu F, Previti ML, Davis J, Grande AM, Robinson JK, Van Nostrand WE. Minocycline reduces microglial activation and improves behavioral deficits in a transgenic model of cerebral microvascular amyloid. J Neurosci 2007; 27:3057-63. [PMID: 17376966 PMCID: PMC6672462 DOI: 10.1523/jneurosci.4371-06.2007] [Citation(s) in RCA: 154] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Cerebral microvascular amyloid beta protein (Abeta) deposition and associated neuroinflammation is increasingly recognized as an important component leading to cognitive impairment in Alzheimer's disease and related cerebral amyloid angiopathy disorders. Transgenic mice expressing the vasculotropic Dutch/Iowa (E693Q/D694N) mutant human Abeta precursor protein in brain (Tg-SwDI) accumulate abundant cerebral microvascular fibrillar amyloid deposits and exhibit robust neuroinflammation. In the present study, we investigated the effect of the anti-inflammatory drug minocycline on Abeta accumulation, neuroinflammation, and behavioral deficits in Tg-SwDI mice. Twelve-month-old mice were treated with saline or minocycline by intraperitoneal injection every other day for a total of 4 weeks. During the final week of treatment, the mice were tested for impaired learning and memory. Brains were then harvested for biochemical and immunohistochemical analysis. Minocycline treatment did not alter the cerebral deposition of Abeta or the restriction of fibrillar amyloid to the cerebral microvasculature. Similarly, minocycline-treated Tg-SwDI mice exhibited no change in the levels of total Abeta, the ratios of Abeta40 and Abeta42, or the amounts of soluble, insoluble, or oligomeric Abeta compared with the saline-treated control Tg-SwDI mice. In contrast, the numbers of activated microglia and levels of interleukin-6 were significantly reduced in minocycline-treated Tg-SwDI mice compared with saline-treated Tg-SwDI mice. In addition, there was a significant improvement in behavioral performance of the minocycline-treated Tg-SwDI mice. These finding suggest that anti-inflammatory treatment targeted for cerebral microvascular amyloid-induced microglial activation can improve cognitive deficits without altering the accumulation and distribution of Abeta.
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825
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Chin J, Massaro CM, Palop JJ, Thwin MT, Yu GQ, Bien-Ly N, Bender A, Mucke L. Reelin depletion in the entorhinal cortex of human amyloid precursor protein transgenic mice and humans with Alzheimer's disease. J Neurosci 2007; 27:2727-33. [PMID: 17360894 PMCID: PMC6672562 DOI: 10.1523/jneurosci.3758-06.2007] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Reelin regulates nervous system development and modulates synaptic plasticity in the adult brain. Several findings suggest that alterations in Reelin signaling may contribute to neuronal dysfunction associated with Alzheimer's disease (AD). Cell surface receptors for Reelin, including integrins and very-low-density lipoprotein receptor/apolipoprotein E2 receptor, may be targets of amyloid-beta (Abeta) peptides presumed to play key roles in the pathogenesis of AD. Reelin also regulates the extent of tau phosphorylation. Finally, increased amounts of Reelin fragments have been found in CSF from AD patients, suggesting altered processing of Reelin. We therefore hypothesized that Reelin levels might be altered in the brains of human amyloid precursor protein (hAPP) transgenic mice, particularly in brain regions vulnerable to AD such as hippocampus and entorhinal cortex. Compared with nontransgenic controls, hAPP mice had significantly fewer Reelin-expressing pyramidal cells in the entorhinal cortex, the major population of glutamatergic neurons expressing Reelin in the brain. Western blot analysis of the hippocampus, which receives projections from the entorhinal cortex, revealed significant reductions in Reelin levels. In contrast, the number of Reelin-expressing GABAergic interneurons was not altered in either the entorhinal cortex or the hippocampus. Thus, neuronal expression of hAPP/Abeta is sufficient to reduce Reelin expression in a specific population of entorhinal cortical pyramidal neurons in vivo. Underscoring the relevance of these findings, we found qualitatively similar reductions of Reelin-expressing pyramidal neurons in the entorhinal cortex of AD brains. We conclude that alterations in Reelin processing or signaling may be involved in AD-related neuronal dysfunction.
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Affiliation(s)
- Jeannie Chin
- Gladstone Institute of Neurological Disease
- Department of Neurology, and
| | - Catherine M. Massaro
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, California 94158
| | - Jorge J. Palop
- Gladstone Institute of Neurological Disease
- Department of Neurology, and
| | | | - Gui-Qiu Yu
- Gladstone Institute of Neurological Disease
| | | | | | - Lennart Mucke
- Gladstone Institute of Neurological Disease
- Department of Neurology, and
- Neuroscience Graduate Program, University of California, San Francisco, San Francisco, California 94158
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826
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De Felice FG, Wu D, Lambert MP, Fernandez SJ, Velasco PT, Lacor PN, Bigio EH, Jerecic J, Acton PJ, Shughrue PJ, Chen-Dodson E, Kinney GG, Klein WL. Alzheimer's disease-type neuronal tau hyperphosphorylation induced by A beta oligomers. Neurobiol Aging 2007; 29:1334-47. [PMID: 17403556 PMCID: PMC3142933 DOI: 10.1016/j.neurobiolaging.2007.02.029] [Citation(s) in RCA: 310] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 02/26/2007] [Accepted: 02/27/2007] [Indexed: 01/03/2023]
Abstract
Alzheimer's disease (AD) is characterized by presence of extracellular fibrillar A beta in amyloid plaques, intraneuronal neurofibrillary tangles consisting of aggregated hyperphosphorylated tau and elevated brain levels of soluble A beta oligomers (ADDLs). A major question is how these disparate facets of AD pathology are mechanistically related. Here we show that, independent of the presence of fibrils, ADDLs stimulate tau phosphorylation in mature cultures of hippocampal neurons and in neuroblastoma cells at epitopes characteristically hyperphosphorylated in AD. A monoclonal antibody that targets ADDLs blocked their attachment to synaptic binding sites and prevented tau hyperphosphorylation. Tau phosphorylation was blocked by the Src family tyrosine kinase inhibitor, 4-amino-5-(4-chlorophenyl)-7(t-butyl)pyrazol(3,4-D)pyramide (PP1), and by the phosphatidylinositol-3-kinase inhibitor LY294002. Significantly, tau hyperphosphorylation was also induced by a soluble aqueous extract containing A beta oligomers from AD brains, but not by an extract from non-AD brains. A beta oligomers have been increasingly implicated as the main neurotoxins in AD, and the current results provide a unifying mechanism in which oligomer activity is directly linked to tau hyperphosphorylation in AD pathology.
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Affiliation(s)
- Fernanda G. De Felice
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
- Instituto de Bioquíica Médica, Programa de Bioquímica e Biofísica Celular, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ 21944-590, Brazil
| | - Diana Wu
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
| | - Mary P. Lambert
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
| | - Sara J. Fernandez
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
| | - Pauline T. Velasco
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
| | - Pascale N. Lacor
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
| | - Eileen H. Bigio
- Neuropathology Core, Cognitive Neurology and Alzheimer’s Disease Center, Northwestern Feinberg School of Medicine, Chicago, IL 60611 USA
| | - Jasna Jerecic
- Acumen Pharmaceuticals, Inc., South San Francisco, CA 94080 USA
| | - Paul J. Acton
- Merck Research Laboratories, Department of Alzheimer’s Research, West Point, PA 19486 USA
| | - Paul J. Shughrue
- Merck Research Laboratories, Department of Alzheimer’s Research, West Point, PA 19486 USA
| | - Elizabeth Chen-Dodson
- Merck Research Laboratories, Department of Alzheimer’s Research, West Point, PA 19486 USA
| | - Gene G. Kinney
- Merck Research Laboratories, Department of Alzheimer’s Research, West Point, PA 19486 USA
| | - William L. Klein
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois, 60208 USA
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827
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Holscher C, Gengler S, Gault VA, Harriott P, Mallot HA. Soluble beta-amyloid[25–35] reversibly impairs hippocampal synaptic plasticity and spatial learning. Eur J Pharmacol 2007; 561:85-90. [PMID: 17320856 DOI: 10.1016/j.ejphar.2007.01.040] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2006] [Revised: 01/09/2007] [Accepted: 01/12/2007] [Indexed: 11/29/2022]
Abstract
Beta-amyloid is a peptide that appears to be responsible for cognitive impairments in patients with Alzheimer's disease. Recent research shows that soluble oligomers of beta-amyloid affect synaptic activity and learning, well before any amyloid has aggregated into plaques. Here we show that injection of 3x10 nmol amyloid [25-35] i.c.v. transiently impairs learning of a radial arm maze and the induction of hippocampal long-term potentiation. Furthermore, hippocampal field potentials had been recorded over a period of 21 days and were found to be reduced from day 9 to day 15 (P<0.001), after which the reduction had reversed to baseline. In the spatial 8-arm learning task, animals had to learn which 3 out of 8 arms had been baited. A significant impairment of working and long-term memory was observed at day 12-20 (P<0.001), but not at days 3-11 or 20-28. Long-term potentiation induction in the hippocampus area CA1 was also impaired at day 12-20 (P<0.001), but not at other days. A scrambled peptide sequence version of amyloid did not have any effect. These results emphasise that soluble amyloid fragments already have detrimental effects on brain function well before aggregation occurs. They also show that these effects are reversible, and therefore most likely do not involve neuronal death. The neurodegeneration seen in Alzheimer's disease brains is most likely a downstream effect, linked to processes such as immune response activation and free radical production. These results suggest that treatment at very early stages of Alzheimer's disease could prevent later irreversible neuronal degeneration.
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828
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Chauhan NB. Intracerebroventricular passive immunization with anti-oligoAbeta antibody in TgCRND8. J Neurosci Res 2007; 85:451-63. [PMID: 17086547 DOI: 10.1002/jnr.21110] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Based on the central dogma of beta-amyloid (Abeta) as a key seeding event in the pathogenesis of Alzheimer disease (AD), immunoneutralization strategies have been actively pursued both in AD and in models of AD as a potential means for treating AD. Both active and passive immunizations targeted at fibrillar Abeta successfully remove cerebral plaque load and attenuate Abeta-induced toxicity. Consistently with this, intracerebroventricular (ICV) passive immunization established in our laboratory using antibody against fibrillar Abeta (anti-fAbeta) reduced cerebral plaque load and reversed early synaptic deficits at pre/early plaque stage when there is an abundance of soluble dimeric/oligomeric Abeta but sparse fibrillar Abeta, indicating that anti-fAbeta-mediated partial neutralization of toxic oligomeric Abeta species might have reduced early synaptotoxicity. In the previous investigation, we found that immunoneutralization with anti-fAbeta transiently reduced cerebral Abeta and associated toxicity. The current investigation tested whether ICV im munization using antibody to conformationally changed oligomeric Abeta (anti-oligoAbeta) will overcome the transient restorative nature of anti-fAbeta and produce persistent, long-lasting preventive effects. Because oligomeric Abeta is strongly correlated with synaptotoxicity, we investigated whether immunoneutralization of oligomeric Abeta will reverse synaptic deficits by analyzing presynaptic molecular marker (SNAP-25) profile within hippocampal dendritic fields, where SNAP-25 is abundantly expressed. Results show that, in contrast to ICV anti-fAbeta antibody, ICV anti-oligoAbeta antibody significantly prevented cerebral Abeta build and almost completely restored SNAP-25 immunoreaction up to 8 weeks postinjection in TgCRND8 brain. Results show that ICV passive immunization with anti-oligoAbeta antibody might be an improved ICV immunization strategy for preventing permanent structural damage in AD.
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Affiliation(s)
- Neelima B Chauhan
- Research and Development (151), Jesse Brown VA Medical Center Chicago, Chicago, Illinois 60612, USA.
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829
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Hu M, Schurdak ME, Puttfarcken PS, El Kouhen R, Gopalakrishnan M, Li J. High content screen microscopy analysis of A beta 1-42-induced neurite outgrowth reduction in rat primary cortical neurons: neuroprotective effects of alpha 7 neuronal nicotinic acetylcholine receptor ligands. Brain Res 2007; 1151:227-35. [PMID: 17449017 DOI: 10.1016/j.brainres.2007.03.051] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 03/05/2007] [Accepted: 03/06/2007] [Indexed: 12/14/2022]
Abstract
beta-Amyloid peptide 1-42 (A beta(1-42)) is generated from amyloid precursor protein (APP) and associated with neurodegeneration in Alzheimer's disease (AD). A beta(1-42) has been shown to be cytotoxic when incubated with cultured neurons. However, APP transgenic mice over-expressing A beta(1-42) do not show substantial loss of neurons, despite deficits in learning and memory. It is thus emerging that A beta(1-42)-induced memory deficits may involve subtler neuronal alternations leading to synaptic deficits, prior to frank neurodegeneration in AD brains. In this study, high content screen (HCS) microscopy, an advanced high-throughput cellular image processing and analysis technique, was utilized in establishing an in vitro model of A beta(1-42)-induced neurotoxicity utilizing rat neonatal primary cortical cells. Neurite outgrowth was found to be significantly reduced by A beta(1-42) (300 nM to 30 microM), but not by the scrambled control peptide control, in a time- and concentration-dependent manner. In contrast, no reduction in the total number of neurons was observed. The A beta(1-42)-induced reduction of neurite outgrowth was attenuated by the NMDA receptor antagonist memantine and the alpha 7 nicotinic acetylcholine receptor (nAChR) selective agonist PNU-282987. Interestingly, the alpha 7 nAChR antagonist methyllycaconitine also significantly prevented reduction in A beta(1-42)-induced neurite outgrowth. The observed neuroprotective effects could arise either from interference of A beta(1-42) interactions with alpha 7 nAChRs or by modification of receptor-mediated signaling pathways. Our studies demonstrate that reduction of neurite outgrowth may serve as a model representing A beta(1-42)-mediated neuritic and synaptic toxicity, which, in combination of HCS, provides a high-throughput cell-based assay that can be used to evaluate compounds with neuroprotective properties in neurons.
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Affiliation(s)
- Min Hu
- Neuroscience Research, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064-6125, USA
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830
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Sun L, Wang L, Sun Y, Tang SW, Hu Y. Protective effects of EUK4010 on beta-amyloid(1-42) induced degeneration of neuronal cells. Eur J Neurosci 2007; 24:1011-9. [PMID: 16930428 DOI: 10.1111/j.1460-9568.2006.04951.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
EUK4010 has been identified to exhibit an inhibitory effect on beta-amyloid (Abeta)(1-42)-induced loss of neuronal cell viability. Further studies demonstrated that EUK4010 attenuated the Abeta(1-42)-induced degeneration in both cultured rat hippocampal neurons and human neuroblastoma cells, as demonstrated by typical morphological changes, cell viability and the chip-based flow cytometric assay. Gene expression analysis using DNA microarray showed that the senescence marker calcium-binding protein, regucalcin (Rgn), GABA-A receptor pi subunit (Gabrp), the huntingtin binding protein, optineurin (Optn) and a semaphorin family plexin A3 similar protein (Plex-similar) changed their expression levels significantly in cultured neurons after Abeta(1-42) treatment. In this report, we have undertaken a chemical genetic approach to study the molecular basis of Abeta(1-42) effects on the neuronal degeneration. Our results demonstrate that EUK4010 completely blocked the Abeta(1-42)-induced up-regulation of GABA-A receptor pi subunit and the semaphorin family plexin A3 similar protein, and partially attenuated the down-regulation of senescence marker calcium-binding protein, regucalcin. These observations suggest that EUK4010 may prevent or reduce the Abeta toxicity by regulating the expression of genes involved in the Abeta induced neuronal degeneration. These genes may represent a promising target for the therapeutic drug development for Alzheimer's disease (AD) and other neurological disorders. Furthermore, EUK4010 and its analogues could potentially be developed as neuronal protective agents for the treatment of these diseases.
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Affiliation(s)
- Liwen Sun
- Biophysics lab of Brain Function, College of Life Sciences, Zhejiang University, Hangzhou 310027, China
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831
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Uemura K, Kuzuya A, Aoyagi N, Ando K, Shimozono Y, Ninomiya H, Shimohama S, Kinoshita A. Amyloid β inhibits ectodomain shedding of N-cadherin via down-regulation of cell-surface NMDA receptor. Neuroscience 2007; 145:5-10. [PMID: 17257767 DOI: 10.1016/j.neuroscience.2006.12.022] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2006] [Revised: 12/10/2006] [Accepted: 12/11/2006] [Indexed: 11/29/2022]
Abstract
Dysfunction in the synapse is recognized as an early and the primary pathological process in Alzheimer's disease (AD). N-cadherin, an essential adhesion molecule for excitatory synaptic contact, forms a complex with presenilin 1 (PS1) and beta-catenin in the synaptic membrane. N-cadherin is sequentially cleaved by ADAM10 and PS1/gamma-secretase, producing a cytoplasmic fragment, N-cadherin C-terminal fragment (Ncad/CTF2) after NMDA receptor stimulation [Marambaud P, Wen PH, Dutt A, Shioi J, Takashima A, Siman R, Robakis NK (2003) A CBP binding transcriptional repressor produced by the PS1/epsilon-cleavage of N-cadherin is inhibited by PS1 FAD mutations. Cell 114:635-645; Reiss K, Maretzky T, Ludwig A, Tousseyn T, de Strooper B, Hartmann D, Saftig P (2005) ADAM10 cleavage of N-cadherin and regulation of cell-cell adhesion and beta-catenin nuclear signalling. EMBO J 24:1762]. Ncad/CTF2 translocates to the nucleus together with beta-catenin to enhance beta-catenin nuclear signaling [Uemura K, Kihara T, Kuzuya A, Okawa K, Nishimoto T, Bito H, Ninomiya H, Sugimoto H, Kinoshita A, Shimohama S (2006a) Activity-dependent regulation of beta-catenin via epsilon-cleavage of N-cadherin. Biochem Biophys Res Commun 345:951-958]. To examine whether an impairment of N-cadherin metabolism is involved in AD pathogenesis, we investigated the effect of amyloid beta peptide (Abeta) treatment on sequential N-cadherin cleavage. Here, we demonstrate that both synthetic and cell-derived Abeta species inhibit ectodomain shedding of mouse N-cadherin. Inhibition of N-cadherin cleavage by Abeta treatment was suggested to be mediated by the enhanced endocytosis of NMDA receptor, resulting in reduced turnover of N-cadherin. Since both N-cadherin and beta-catenin are essential for synaptic plasticity, impairment of N-cadherin cleavage caused by Abeta may underlie the synapse toxicity involved in AD pathogenesis.
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Affiliation(s)
- K Uemura
- Horizontal Medical Research Organization, Kyoto University Graduate School of Medicine, Kyoto, Japan 606-8507
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832
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Xu F, Grande AM, Robinson JK, Previti ML, Vasek M, Davis J, Van Nostrand WE. Early-onset subicular microvascular amyloid and neuroinflammation correlate with behavioral deficits in vasculotropic mutant amyloid beta-protein precursor transgenic mice. Neuroscience 2007; 146:98-107. [PMID: 17331655 PMCID: PMC1949338 DOI: 10.1016/j.neuroscience.2007.01.043] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 01/16/2007] [Accepted: 01/20/2007] [Indexed: 11/19/2022]
Abstract
Cerebral microvascular amyloid beta protein (Abeta) deposition and associated neuroinflammation are increasingly recognized as an important component leading to cognitive impairment in Alzheimer's disease and related cerebral amyloid angiopathy (CAA) disorders. Transgenic mice expressing the vasculotropic Dutch/Iowa (E693Q/D694N) mutant human Abeta precursor protein in brain (Tg-SwDI) accumulate abundant cerebral microvascular fibrillar amyloid deposits exhibiting robust neuroinflammation. In the present study, we sought to determine if the unique amyloid pathology of Tg-SwDI mice was associated with deficits in behavioral performance. Behavioral performance tests that assessed a variety of psychological functions, including overall activity, motor ability, balance and strength, anxiety, impulsivity, and learning were conducted on homozygous Tg-SwDI mice and similarly aged wild-type C57Bl/6 mice. Our results indicate that Tg-SwDI mice were impaired in the performance of the Barnes maze learning and memory task at 3, 9, and 12 months of age. While more widespread cerebral microvascular Abeta pathology was evident in older animals, the evaluation of the Abeta pathology in the 3 months old transgenic animals revealed specific accumulation of microvascular amyloid and markedly elevated numbers of reactive astrocytes and activated microglia restricted to the subiculum. These findings indicate that early-onset accumulation of subicular microvascular amyloid and accompanying neuroinflammation correlates with impaired performance in the learning and memory task in Tg-SwDI mice.
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Affiliation(s)
- Feng Xu
- Department of Medicine, Stony Brook University Stony Brook, NY 1179
| | - Alicia M. Grande
- Department of Psychology, Stony Brook University Stony Brook, NY 1179
| | - John K. Robinson
- Department of Psychology, Stony Brook University Stony Brook, NY 1179
| | - Mary Lou Previti
- Department of Medicine, Stony Brook University Stony Brook, NY 1179
| | - Michael Vasek
- Department of Medicine, Stony Brook University Stony Brook, NY 1179
| | - Judianne Davis
- Department of Medicine, Stony Brook University Stony Brook, NY 1179
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833
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Cachard-Chastel M, Lezoualc'h F, Dewachter I, Deloménie C, Croes S, Devijver H, Langlois M, Van Leuven F, Sicsic S, Gardier AM. 5-HT4 receptor agonists increase sAPPalpha levels in the cortex and hippocampus of male C57BL/6j mice. Br J Pharmacol 2007; 150:883-92. [PMID: 17325649 PMCID: PMC2013878 DOI: 10.1038/sj.bjp.0707178] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND AND PURPOSE A strategy to treat Alzheimer's disease (AD) is to increase the soluble form of amyloid precursor protein (sAPPalpha), a promnesic protein, in the brain. Because strong evidence supports beneficial effects of 5-hydroxytryptamine 5-HT(4) receptor agonists in memory and learning, we investigated the role of 5-HT(4) receptors on APP processing in 8 weeks-old male C57BL/6j mice. EXPERIMENTAL APPROACH Mice were given, subcutaneously, prucalopride or ML 10302 (s.c.), two highly selective 5-HT(4) receptor agonists and, up to 240 min later, the hippocampus and cortex were analysed by Western blot for sAPPalpha determination. KEY RESULTS Prucalopride (5 or 10 mg kg(-1)) significantly increased sAPPalpha levels in the hippocampus and cortex, but did not modify the expression level of APP mRNA as detected by quantitative RT-PCR. A selective 5-HT(4) receptor antagonist, GR125487 (1 mg kg(-1), s.c.) inhibited prucalopride induced- increase in sAPPalpha levels. In addition, levels of sAPPalpha were increased by ML10302 only at 20 mg kg(-1) and was limited to the cortex. Also, prucalopride increased sAPPalpha levels in the cortex of a transgenic mouse model of AD, expressing the London mutation of APP. Furthermore, the combined injection of a selective acetylcholinesterase inhibitor, donepezil and prucalopride induced a synergic increase in sAPPalpha levels in the cortex and hippocampus. CONCLUSIONS AND IMPLICATIONS Our results demonstrate that the 5-HT(4) receptor plays a key role in the non-amyloidogenic pathway of APP metabolism in vivo and give support to the beneficial use of 5-HT(4) agonists for AD treatment.
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Affiliation(s)
- M Cachard-Chastel
- EA3544, Sérotonine et Neuropharmacologie, Faculté de Pharmacie, Universite Paris-Sud Châtenay-Malabry cedex, France
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - F Lezoualc'h
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- INSERM, U769, Signalisation et Physiopathologie Cardiaque, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - I Dewachter
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - C Deloménie
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - S Croes
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - H Devijver
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - M Langlois
- BIOCIS, Laboratoire de Reconnaissance Moléculaire et Synthèse, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - F Van Leuven
- Experimental Genetics Group, KULeuven, Campus Gasthuisberg Leuven, Belgium
| | - S Sicsic
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- BIOCIS, Laboratoire de Reconnaissance Moléculaire et Synthèse, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
| | - A M Gardier
- EA3544, Sérotonine et Neuropharmacologie, Faculté de Pharmacie, Universite Paris-Sud Châtenay-Malabry cedex, France
- IFR-141, Faculté de Pharmacie, Université Paris-Sud Châtenay-Malabry cedex, France
- Author for correspondence:
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834
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Townsend M, Cleary JP, Mehta T, Hofmeister J, Lesne S, O'Hare E, Walsh DM, Selkoe DJ. Orally available compound prevents deficits in memory caused by the Alzheimer amyloid-beta oligomers. Ann Neurol 2007; 60:668-76. [PMID: 17192927 DOI: 10.1002/ana.21051] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OBJECTIVE Despite progress in defining a pathogenic role for amyloid beta protein (Abeta) in Alzheimer's disease, orally bioavailable compounds that prevent its effects on hippocampal synaptic plasticity and cognitive function have not yet emerged. A particularly attractive therapeutic strategy is to selectively neutralize small, soluble Abeta oligomers that have recently been shown to mediate synaptic dysfunction. METHODS Using electrophysiological, biochemical, and behavioral assays, we studied how scyllo-inositol (AZD-103; molecular weight, 180) neutralizes the acutely toxic effects of Abeta on synaptic function and memory recall. RESULTS Scyllo-inositol, but not its stereoisomer, chiro-inositol, dose-dependently rescued long-term potentiation in mouse hippocampus from the inhibitory effects of soluble oligomers of cell-derived human Abeta. Cerebroventricular injection into rats of the soluble Abeta oligomers interfered with learned performance on a complex lever-pressing task, but administration of scyllo-inositol via the drinking water fully prevented oligomer-induced errors. INTERPRETATION A small, orally available natural product penetrates into the brain in vivo to rescue the memory impairment produced by soluble Abeta oligomers through a mechanism that restores hippocampal synaptic plasticity.
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Affiliation(s)
- Matthew Townsend
- Center for Neurologic Diseases, Harvard Medical School and Brigham and Women's Hospital, Boston, MA, USA
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835
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Lacor PN, Buniel MC, Furlow PW, Sanz Clemente A, Velasco PT, Wood M, Viola KL, Klein WL. Abeta oligomer-induced aberrations in synapse composition, shape, and density provide a molecular basis for loss of connectivity in Alzheimer's disease. J Neurosci 2007; 27:796-807. [PMID: 17251419 PMCID: PMC6672917 DOI: 10.1523/jneurosci.3501-06.2007] [Citation(s) in RCA: 924] [Impact Index Per Article: 54.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The basis for memory loss in early Alzheimer's disease (AD) seems likely to involve synaptic damage caused by soluble Abeta-derived oligomers (ADDLs). ADDLs have been shown to build up in the brain and CSF of AD patients and are known to interfere with mechanisms of synaptic plasticity, acting as gain-of-function ligands that attach to synapses. Because of the correlation between AD dementia and synaptic degeneration, we investigated here the ability of ADDLs to affect synapse composition, structure, and abundance. Using highly differentiated cultures of hippocampal neurons, a preferred model for studies of synapse cell biology, we found that ADDLs bound to neurons with specificity, attaching to presumed excitatory pyramidal neurons but not GABAergic neurons. Fractionation of ADDLs bound to forebrain synaptosomes showed association with postsynaptic density complexes containing NMDA receptors, consistent with observed attachment of ADDLs to dendritic spines. During binding to hippocampal neurons, ADDLs promoted a rapid decrease in membrane expression of memory-related receptors (NMDA and EphB2). Continued exposure resulted in abnormal spine morphology, with induction of long thin spines reminiscent of the morphology found in mental retardation, deafferentation, and prionoses. Ultimately, ADDLs caused a significant decrease in spine density. Synaptic deterioration, which was accompanied by decreased levels of the spine cytoskeletal protein drebrin, was blocked by the Alzheimer's therapeutic drug Namenda. The observed disruption of dendritic spines links ADDLs to a major facet of AD pathology, providing strong evidence that ADDLs in AD brain cause neuropil damage believed to underlie dementia.
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Affiliation(s)
- Pascale N. Lacor
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Maria C. Buniel
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Paul W. Furlow
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Antonio Sanz Clemente
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Pauline T. Velasco
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Margaret Wood
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - Kirsten L. Viola
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
| | - William L. Klein
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208
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836
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Puglielli L. Aging of the brain, neurotrophin signaling, and Alzheimer's disease: is IGF1-R the common culprit? Neurobiol Aging 2007; 29:795-811. [PMID: 17313996 PMCID: PMC2387053 DOI: 10.1016/j.neurobiolaging.2007.01.010] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2006] [Revised: 09/21/2006] [Accepted: 01/13/2007] [Indexed: 12/26/2022]
Abstract
The last decade has revealed that the lifespan of an organism can be modulated by the signaling pathway that acts downstream of the insulin/insulin-like growth factor 1 receptors (IR/IGF1-R), indicating that there is a "program" that drives the process of aging. New results have now linked the same pathway to the neurogenic capacities of the aging brain, to neurotrophin signaling, and to the molecular pathogenesis of Alzheimer's disease. Therefore, a common signaling cascade now seems to link aging to age-associated pathologies of the brain, suggesting that pharmacologic approaches aimed at the modulation of this pathway can serve to delay the onset of age-associated disorders and improve the quality of life. Work from a wide range of fields performed with different approaches has already identified some of the signaling molecules that act downstream of IGF1-R, and has revealed that a delicate checkpoint exists to balance excessive growth/"immortality" and reduced growth/"senescence" of a cell. Future research will determine how far the connection goes and how much of it we can influence.
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Affiliation(s)
- Luigi Puglielli
- Department of Medicine, University of Wisconsin-Madison, and Geriatric Research Education Clinical Center, VA Medical Center, VAH-GRECC 11G, 2500 Overlook Terrace, Madison, WI 53705, USA.
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837
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De Felice FG, Velasco PT, Lambert MP, Viola K, Fernandez SJ, Ferreira ST, Klein WL. Abeta oligomers induce neuronal oxidative stress through an N-methyl-D-aspartate receptor-dependent mechanism that is blocked by the Alzheimer drug memantine. J Biol Chem 2007; 282:11590-601. [PMID: 17308309 DOI: 10.1074/jbc.m607483200] [Citation(s) in RCA: 663] [Impact Index Per Article: 39.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Oxidative stress is a major aspect of Alzheimer disease (AD) pathology. We have investigated the relationship between oxidative stress and neuronal binding of Abeta oligomers (also known as ADDLs). ADDLs are known to accumulate in brain tissue of AD patients and are considered centrally related to pathogenesis. Using hippocampal neuronal cultures, we found that ADDLs stimulated excessive formation of reactive oxygen species (ROS) through a mechanism requiring N-methyl-d-aspartate receptor (NMDA-R) activation. ADDL binding to neurons was reduced and ROS formation was completely blocked by an antibody to the extracellular domain of the NR1 subunit of NMDA-Rs. In harmony with a steric inhibition of ADDL binding by NR1 antibodies, ADDLs that were bound to detergent-extracted synaptosomal membranes co-immunoprecipitated with NMDA-R subunits. The NR1 antibody did not affect ROS formation induced by NMDA, showing that NMDA-Rs themselves remained functional. Memantine, an open channel NMDA-R antagonist prescribed as a memory-preserving drug for AD patients, completely protected against ADDL-induced ROS formation, as did other NMDA-R antagonists. Memantine and the anti-NR1 antibody also attenuated a rapid ADDL-induced increase in intraneuronal calcium, which was essential for stimulated ROS formation. These results show that ADDLs bind to or in close proximity to NMDA-Rs, triggering neuronal damage through NMDA-R-dependent calcium flux. This response provides a pathologically specific mechanism for the therapeutic action of memantine, indicates a role for ROS dysregulation in ADDL-induced cognitive impairment, and supports the unifying hypothesis that ADDLs play a central role in AD pathogenesis.
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Affiliation(s)
- Fernanda G De Felice
- Department of Neurobiology and Physiology, Northwestern University, Evanston, Illinois 60208, USA
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838
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Saganich MJ, Schroeder BE, Galvan V, Bredesen DE, Koo EH, Heinemann SF. Deficits in synaptic transmission and learning in amyloid precursor protein (APP) transgenic mice require C-terminal cleavage of APP. J Neurosci 2007; 26:13428-36. [PMID: 17192425 PMCID: PMC6674728 DOI: 10.1523/jneurosci.4180-06.2006] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Synaptic dysfunction has been shown to be one of the earliest correlates of disease progression in animal models of Alzheimer's disease. Amyloid-beta protein (Abeta) is thought to play an important role in disease-related synaptic dysfunction, but the mechanism by which Abeta leads to synaptic dysfunction is not understood. Here we describe evidence that cleavage of APP in the C terminus may be necessary for the deficits present in APP transgenic mice. In APP transgenic mice with a mutated cleavage site at amino acid 664, normal synaptic transmission, synaptic plasticity, and learning were maintained despite the presence of elevated levels of APP, Abeta42, and even plaque accumulation. These results indicate that cleavage of APP may play a critical role in the development of synaptic and behavioral dysfunction in APP transgenic mice.
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839
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Roney C, Kulkarni P, Arora V, Bennett M, Antich P, Bonte F, Wu A, Mallikarjuna NN, Manohar S, Sairam M, Aminabhavi TM. Feature Article: Polymeric Nanoparticulate Drug Delivery Through The Blood Brain Barrier. ACTA ACUST UNITED AC 2007. [DOI: 10.1080/00323910500290374] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Celeste Roney
- a Department of Radiology , Division of Advanced Radiological Sciences
| | - Padmakar Kulkarni
- a Department of Radiology , Division of Advanced Radiological Sciences
| | - Veera Arora
- a Department of Radiology , Division of Advanced Radiological Sciences
| | - Michael Bennett
- b Department of Pathology , The University of Texas, Southwestern Medical Center at Dallas , Dallas , TX , 75390 , USA
| | - Peter Antich
- a Department of Radiology , Division of Advanced Radiological Sciences
| | - Frederick Bonte
- a Department of Radiology , Division of Advanced Radiological Sciences
| | - Aimei Wu
- c Alan G. MacDiarmid Center for Innovation, Department of Chemistry , The University of Texas at Dallas , Richardson , TX , 75083 , USA
| | - N. N. Mallikarjuna
- c Alan G. MacDiarmid Center for Innovation, Department of Chemistry , The University of Texas at Dallas , Richardson , TX , 75083 , USA
| | - Sanjeev Manohar
- c Alan G. MacDiarmid Center for Innovation, Department of Chemistry , The University of Texas at Dallas , Richardson , TX , 75083 , USA
| | - Malladi Sairam
- d Drug Delivery Division, Center of Excellence in Polymer Science , The Karnatak University , Dharwad , 580003 , India
| | - Tejraj M. Aminabhavi
- d Drug Delivery Division, Center of Excellence in Polymer Science , The Karnatak University , Dharwad , 580003 , India
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840
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Campiglia P, Esposito C, Scrima M, Gomez-Monterrey I, Bertamino A, Grieco P, Novellino E, D'Ursi AM. Conformational Stability of A?-(25?35) in the Presence of Thiazolidine Derivatives. Chem Biol Drug Des 2007; 69:111-8. [PMID: 17381724 DOI: 10.1111/j.1747-0285.2007.00482.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In the attempt to identify a new lead compound able to modify the conformational preferences of the beta-amyloid peptides, a set of new compounds characterized by a thiazolidine ring linked to several different aryl moieties were synthesized. The ability of these compounds to prevent the beta-amyloid aggregation was evaluated using circular dichroism and nuclear magnetic resonance techniques. Molecular docking procedure allowed an interpretation of spectroscopic in the key of molecular interaction.
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Affiliation(s)
- Pietro Campiglia
- Dipartimento di Scienze Farmaceutiche, University of Salerno, 84084 Fisciano, Italy
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841
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Riddell DR, Zhou H, Comery TA, Kouranova E, Lo CF, Warwick HK, Ring RH, Kirksey Y, Aschmies S, Xu J, Kubek K, Hirst WD, Gonzales C, Chen Y, Murphy E, Leonard S, Vasylyev D, Oganesian A, Martone RL, Pangalos MN, Reinhart PH, Jacobsen JS. The LXR agonist TO901317 selectively lowers hippocampal Abeta42 and improves memory in the Tg2576 mouse model of Alzheimer's disease. Mol Cell Neurosci 2007; 34:621-8. [PMID: 17336088 DOI: 10.1016/j.mcn.2007.01.011] [Citation(s) in RCA: 194] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2006] [Revised: 01/05/2007] [Accepted: 01/18/2007] [Indexed: 10/23/2022] Open
Abstract
Recent studies show that intracellular cholesterol levels can modulate the processing of amyloid precursor protein to Abeta peptide. Moreover, cholesterol-rich apoE-containing lipoproteins may also promote Abeta clearance. Agonists of the liver X receptor (LXR) transcriptionally induce genes involved in intracellular lipid efflux and transport, including apoE. Thus, LXR agonists have the potential to both inhibit APP processing and promote Abeta clearance. Here we show that LXR agonist, TO901317, increased hippocampal ABCA1 and apoE and decreased Abeta42 levels in APP transgenic mice. TO901317 had no significant effects on levels of Abeta40, full length APP, or the APP processing products. Next, we examined the effects of TO901317 in the contextual fear conditioning paradigm; TO901317 completely reversed the contextual memory deficit in these mice. These data demonstrate that LXR agonists do not directly inhibit APP processing but rather facilitate the clearance of Abeta42 and may represent a novel therapeutic approach to Alzheimer's disease.
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Affiliation(s)
- David R Riddell
- Discovery Neuroscience, Wyeth Research, CN8000, Princeton, NJ 08543, USA.
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842
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Abstract
Neuroinflammation is a host defense mechanism associated with neutralization of an insult and restoration of normal structure and function of brain. Neuroinflammation is a hallmark of all major CNS diseases. The main mediators of neuroinflammation are microglial cells. These cells are activated during a CNS injury. Microglial cells initiate a rapid response that involves cell migration, proliferation, release of cytokines/chemokines and trophic and/or toxic effects. Cytokines/chemokines stimulate phospholipases A2 and cyclooxygenases. This results in breakdown of membrane glycerophospholipids with the release of arachidonic acid (AA) and docosahexaenoic acid (DHA). Oxidation of AA produces pro-inflammatory prostaglandins, leukotrienes, and thromboxanes. One of the lyso-glycerophospholipids, the other products of reactions catalyzed by phospholipase A2, is used for the synthesis of pro-inflammatory platelet-activating factor. These pro-inflammatory mediators intensify neuroinflammation. Lipoxin, an oxidized product of AA through 5-lipoxygenase, is involved in the resolution of inflammation and is anti-inflammatory. Docosahexaenoic acid is metabolized to resolvins and neuroprotectins. These lipid mediators inhibit the generation of prostaglandins, leukotrienes, and thromboxanes. Levels of prostaglandins, leukotrienes, and thromboxanes are markedly increased in acute neural trauma and neurodegenerative diseases. Docosahexaenoic acid and its lipid mediators prevent neuroinflammation by inhibiting transcription factor NFkappaB, preventing cytokine secretion, blocking the synthesis of prostaglandins, leukotrienes, and thromboxanes, and modulating leukocyte trafficking. Depending on its timing and magnitude in brain tissue, inflammation serves multiple purposes. It is involved in the protection of uninjured neurons and removal of degenerating neuronal debris and also in assisting repair and recovery processes. The dietary ratio of AA to DHA may affect neurodegeneration associated with acute neural trauma and neurodegenerative diseases. The dietary intake of docosahexaenoic acid offers the possibility of counter-balancing the harmful effects of high levels of AA-derived pro-inflammatory lipid mediators.
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Affiliation(s)
- Akhlaq A Farooqui
- Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, Ohio 43210, USA
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843
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Rosario ER, Carroll JC, Oddo S, LaFerla FM, Pike CJ. Androgens regulate the development of neuropathology in a triple transgenic mouse model of Alzheimer's disease. J Neurosci 2007; 26:13384-9. [PMID: 17182789 PMCID: PMC6674990 DOI: 10.1523/jneurosci.2514-06.2006] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Normal age-related testosterone depletion in men is a recently identified risk factor for Alzheimer's disease (AD), but how androgen loss affects the development of AD is unclear. To investigate the relationship between androgen depletion and AD, we compared how androgen status affects the progression of neuropathology in the triple transgenic mouse model of AD (3xTg-AD). Adult male 3xTg-AD mice were sham gonadectomized (GDX) or GDX to deplete endogenous androgens and then exposed for 4 months to either the androgen dihydrotestosterone (DHT) or to placebo. In comparison to gonadally intact 3xTg-AD mice, GDX mice exhibited robust increases in the accumulation of beta-amyloid (Abeta), the protein implicated as the primary causal factor in AD pathogenesis, in both hippocampus and amygdala. In parallel to elevated levels of Abeta, GDX mice exhibited significantly impaired spontaneous alternation behavior, indicating deficits in hippocampal function. Importantly, DHT treatment of GDX 3xTg-AD mice attenuated both Abeta accumulation and behavioral deficits. These data demonstrate that androgen depletion accelerates the development of AD-like neuropathology, suggesting that a similar mechanism may underlie the increased risk for AD in men with low testosterone. In addition, our finding that DHT protects against acceleration of AD-like neuropathology predicts that androgen-based hormone therapy may be a useful strategy for the prevention and treatment of AD in aging men.
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Affiliation(s)
| | | | - Salvatore Oddo
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California 92697
| | - Frank M. LaFerla
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, California 92697
| | - Christian J. Pike
- Neuroscience Graduate Program and
- Davis School of Gerontology, University of Southern California, Los Angeles, California 90089, and
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844
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Baron R, Harpaz I, Nemirovsky A, Cohen H, Monsonego A. Immunity and neuronal repair in the progression of Alzheimer’s disease: A brief overview. Exp Gerontol 2007; 42:64-9. [PMID: 17074458 DOI: 10.1016/j.exger.2006.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2006] [Accepted: 07/05/2006] [Indexed: 11/22/2022]
Abstract
Alzheimer's disease (AD) is an age-related progressive neurodegenerative disorder characterized by memory loss and severe cognitive decline. The etiology of the disease has not been explored, although a significant body of evidence suggests that neuronal dysfunction is caused by hyperphosphorylation and intracellular accumulation of the Tau protein, extracellular accumulation of the amyloid beta-peptide (Abeta), and the associated chronic activation of glial cells. Clearance of toxic Abeta, apoptotic cells and debris from the brain together with induction of neuronal repair mechanisms may all take place partially throughout the progression of AD, but therapeutic approaches based on knowledge of these processes have been unsuccessfully developed. Here, we address the question of whether autoimmune mechanisms can be boosted to safely facilitate the above-mentioned clearance and neuronal repair in the AD brain. We have previously demonstrated that depending on genetic background, autoimmunity targeted to Abeta is already induced in elderly individuals and in patients with AD. We have shown in a mouse model of AD that given a preexisting proinflammatory milieu in the brain, immune cells can enter the brain tissue and participate in clearance of Abeta. Furthermore, the decline in cognitive functions and neurogenesis throughout the progression of AD may also be affected by autoimmune mechanisms operating in the periphery and in the brain. In light of the so-far unsuccessful anti-inflammatory approaches to treating AD, we suggest that boosting - rather than suppressing - the endogenous immune mechanisms induced in AD may enhance repair pathways in the brain, provided that this approach can be safely applied.
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Affiliation(s)
- Rona Baron
- Department of Microbiology and Immunology and National Institute of Biotechnology in Negev, Faculty of Health Sciences, Ben-Gurion University of Negev, PO Box 653, Beer-Sheva 84105, Israel
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845
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Minopoli G, Stante M, Napolitano F, Telese F, Aloia L, De Felice M, Di Lauro R, Pacelli R, Brunetti A, Zambrano N, Russo T. Essential Roles for Fe65, Alzheimer Amyloid Precursor-binding Protein, in the Cellular Response to DNA Damage. J Biol Chem 2007; 282:831-5. [PMID: 17121854 DOI: 10.1074/jbc.c600276200] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Fe65 interacts with the cytosolic domain of the Alzheimer amyloid precursor protein (APP). The functions of the Fe65 are still unknown. To address this point we generated Fe65 knockout (KO) mice. These mice do not show any obvious phenotype; however, when fibroblasts (mouse embryonic fibroblasts), isolated from Fe65 KO embryos, were exposed to low doses of DNA damaging agents, such as etoposide or H2O2, an increased sensitivity to genotoxic stress, compared with wild type animals, clearly emerged. Accordingly, brain extracts from Fe65 KO mice, exposed to non-lethal doses of ionizing radiations, showed high levels of gamma-H2AX and p53, thus demonstrating a higher sensitivity to X-rays than wild type mice. Nuclear Fe65 is necessary to rescue the observed phenotype, and few minutes after the exposure of MEFs to DNA damaging agents, Fe65 undergoes phosphorylation in the nucleus. With a similar timing, the proteolytic processing of APP is rapidly affected by the genotoxic stress: in fact, the cleavage of the APP COOH-terminal fragments by gamma-secretase is induced soon after the exposure of cells to etoposide, in a Fe65-dependent manner. These results demonstrate that Fe65 plays an essential role in the response of the cells to DNA damage.
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846
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Abad MA, Enguita M, DeGregorio-Rocasolano N, Ferrer I, Trullas R. Neuronal pentraxin 1 contributes to the neuronal damage evoked by amyloid-beta and is overexpressed in dystrophic neurites in Alzheimer's brain. J Neurosci 2006; 26:12735-47. [PMID: 17151277 PMCID: PMC6674827 DOI: 10.1523/jneurosci.0575-06.2006] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Accumulation of amyloid-beta (Abeta) is thought to play a central role in the progressive loss of synapses, the neurite damage, and the neuronal death that are characteristic in brains affected by Alzheimer's disease. However, the mechanisms through which Abeta produces such neurotoxicity remain unclear. Because Abeta depresses synaptic activity, we investigated whether the neurotoxicity of Abeta depends on the expression of NP1, a protein involved in excitatory synapse remodeling that has recently been shown to mediate neuronal death induced by reduction in neuronal activity in mature neurons. We found that treatment of cortical neurons in culture with Abeta produces a marked increase in NP1 protein that precedes apoptotic neurotoxicity. Silencing NP1 gene expression by RNA interference (short hairpin RNA for RNA interference) prevents the loss of synapses, the reduction in neurite outgrowth, and the apoptosis evoked by Abeta. Transgene overexpression of NP1 reproduced these neurotoxic effects of Abeta. Moreover, we found that NP1 was increased in dystrophic neurites of brains from patients with sporadic late-onset Alzheimer's disease. Dual immunohistochemistry for NP1 and tau showed that NP1 colocalizes with tau deposits in dystrophic neurites. Furthermore, NP1 colocalized with SNAP-25 (synaptosomal-associated protein of 25 kDa) in the majority of dystrophic neurites surrounding amyloid deposits. NP1 was also increased in cell processes surrounding amyloid plaques in the cerebral cortex and hippocampus of APP/PS1 (mutant amyloid precursor protein/presenilin 1) transgenic mice. These findings show that NP1 is a key factor for the synapse loss, the neurite damage, and the apoptotic neuronal death evoked by Abeta and indicate that Abeta contributes to the pathology of Alzheimer's disease by regulating NP1 expression.
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Affiliation(s)
- Maria A. Abad
- Neurobiology Unit, Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain, and
| | - Marta Enguita
- Neurobiology Unit, Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain, and
| | - Nuria DeGregorio-Rocasolano
- Neurobiology Unit, Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain, and
| | - Isidre Ferrer
- Institut de Neuropatologia, Servei Anatomia Patològica, Hospital Universitari de Bellvitge, Universitat de Barcelona, Hospitalet de Llobregat, 08097 Barcelona, Spain
| | - Ramon Trullas
- Neurobiology Unit, Institut d'Investigacions Biomèdiques de Barcelona, Consejo Superior de Investigaciones Científicas, Institut d'Investigacions Biomèdiques August Pi i Sunyer, 08036 Barcelona, Spain, and
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847
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Garcia-Alloza M, Zaldua N, Diez-Ariza M, Marcos B, Lasheras B, Javier Gil-Bea F, Ramirez MJ. Effect of selective cholinergic denervation on the serotonergic system: implications for learning and memory. J Neuropathol Exp Neurol 2006; 65:1074-81. [PMID: 17086104 DOI: 10.1097/01.jnen.0000240469.20167.89] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
The cholinergic system has been widely implicated in cognitive processes and cholinergic loss is a classical hallmark in Alzheimer disease. Increasing evidence supports a role of the serotonergic system in cognition, possibly through a modulation of cholinergic activity. We compared selective cholinergic denervation by administration of the immunotoxin 192 IgG-saporin in the nucleus basalis of Meynert (NBM) with intracerebroventricular (ICV) lesions of the basal forebrain in male rats 7 days after lesioning. NBM lesions induced significant changes in cholinergic markers in the frontal cortex, whereas ICV lesions produced significant decreases in cholinergic markers both in the frontal cortex and hippocampus. Only ICV lesions lead to memory impairments in passive avoidance and Morris water maze tasks. Both models lead to reductions of serotonin levels in the frontal cortex. Similar changes in 5-hydroxytriptophan levels were observed, suggesting a downregulation of the rate-limiting enzyme for the synthesis of serotonin along with the cholinergic deficit. Neither 5-HT1A nor 5-HT1B receptors seem to mediate this process. These data imply that the serotonergic system in the frontal cortex can compensate for diminished cholinergic function and support the investigation of the serotonergic system as a therapeutic target to treat Alzheimer disease.
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Affiliation(s)
- Monica Garcia-Alloza
- Department of Pharmacology, School of Medicine, Centre for Applied Medical Research, University of Navarra, Pamplona, Spain
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848
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Abstract
Alzheimer's disease (AD) is the most common form of dementia in industrialized nations. If more effective therapies are not developed that either prevent AD or block progression of the disease in its very early stages, the economic and societal cost of caring for AD patients will be devastating. Only two types of drugs are currently approved for the treatment of AD: inhibitors of acetyl cholinesterase, which symptomatically enhance cognitive state to some degree but are not disease modifying; and the adamantane derivative, memantine. Memantine preferentially blocks excessive NMDA receptor activity without disrupting normal receptor activity and is thought to be a neuroprotective agent that blocks excitotoxicty. Memantine therefore may have a potentially disease modifying effect in multiple neurodegenerative conditions. An improved understanding of the pathogeneses of AD has now led to the identification of numerous therapeutic targets designed to alter amyloid beta protein (Abeta) or tau accumulation. Therapies that alter Abeta and tau through these various targets are likely to have significant disease modifying effects. Many of these targets have been validated in proof of concept studies in preclinical animal models, and some potentially disease modifying therapies targeting Abeta or tau are being tested in the clinic. This review will highlight both the promise of and the obstacles to developing such disease modifying AD therapies.
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Affiliation(s)
- Todd E Golde
- Mayo Clinic College of Medicine, Department of Neuroscience, Mayo Clinic Jacksonville 4500 San Pablo Road., Jacksonville, Florida 32224, USA.
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849
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Gengler S, Gault VA, Harriott P, Hölscher C. Impairments of hippocampal synaptic plasticity induced by aggregated beta-amyloid (25–35) are dependent on stimulation-protocol and genetic background. Exp Brain Res 2006; 179:621-30. [PMID: 17171334 DOI: 10.1007/s00221-006-0819-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2006] [Accepted: 11/23/2006] [Indexed: 11/26/2022]
Abstract
The aggregation of beta-amyloid to plaques in the brain is one of the hallmarks of Alzheimer disease (AD). Numerous studies have tried to elucidate to what degree amyloid peptides play a role in the neurodegenerative developments seen in AD. While most studies report an effect of amyloid on neural activity and cognitive abilities of rodents, there have been many inconsistencies in the results. This study investigated to what degree the different genetic backgrounds affect the outcome of beta-amyloid fragment (25-35) on synaptic plasticity in vivo in the rat hippocampus. Two strains, Wistar and Lister hooded rats, were tested. In addition, the effects of a strong (600 stimuli) and a weak stimulation protocol (100 stimuli) on impairments of LTP were analysed. Furthermore, since the state of amyloid aggregation appears to play a role in the induction of toxic processes, it was tested by dual polarisation interferometry to what degree and at what speed beta-amyloid (25-35) can aggregate in vitro. It was found that 100 nmol beta-amyloid (25-35) injected icv did impair LTP in Wistar rats when using the weak but not the strong stimulation protocol (P < 0.001). One-hundred nano mole of the reverse sequence amyloid (35-25) had no effect. LTP in Lister Hooded rats was not impaired by amyloid at any stimulation protocol. The aggregation studies showed that amyloid (25-35) aggregated within hours, while amyloid (35-25) did not. These results show that the genetic background and the stimulation protocol are important variables that greatly influence the experimental outcome. The fact that amyloid (25-35) aggregated quickly and showed neurophysiological effects, while amyloid (35-25) did not aggregate and did not show any effects indicates that the state of aggregation plays an important role in the physiological effects.
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Affiliation(s)
- Simon Gengler
- School of Biomedical Sciences, University of Ulster, Cromore Road, Coleraine, BT52 1SA, Northern Ireland
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850
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