101
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Geng D, Kang L, Su Y, Jia J, Ma J, Li S, Du J, Cui H. Protective effects of EphB2 on Aβ1-42 oligomer-induced neurotoxicity and synaptic NMDA receptor signaling in hippocampal neurons. Neurochem Int 2013; 63:283-90. [PMID: 23831214 DOI: 10.1016/j.neuint.2013.06.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/14/2013] [Accepted: 06/15/2013] [Indexed: 12/19/2022]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized pathologically by the abnormal deposition of extracellular amyloid-β (Aβ) oligomers. However, the nature and precise mechanism of the toxicity of Aβ oligomers are not clearly understood. Aβ oligomers have been previously shown to cause a major loss of EphB2, a member of the EphB family of receptor tyrosine kinases. To determine the effect of EphB2 on Aβ oligomer-induced neurotoxicity and the underlying molecular mechanisms, we examined the EphB2 gene in cultured hippocampal neurons. Using a cellular model of AD, Aβ1-42 oligomers were confirmed to induce neurotoxicity in a time-dependent manner and result in a major decrease of EphB2. EphB2 overexpression could prevent the neurotoxicity of hippocampal neurons from exposure to Aβ1-42 oligomers for 1h. Further analysis revealed that EphB2 overexpression increased synaptic NR1 and NR2B expression in Aβ1-42 oligomer-treated neurons. Moreover, EphB2 overexpression prevented Aβ1-42 oligomer-induced downregulation of dephosphorylated p38 MAPK and phosphorylated CREB. Together, these results suggest that EphB2 is a factor which protects hippocampal neurons against the toxicity of Aβ1-42 oligomers, and we infer that the protection of EphB2 is achieved by increasing the synaptic NMDA receptor level and downstream p38 MAPK and CREB signaling in hippocampal neurons. This study provides new molecular insights into the neuroprotective effect of EphB2 and highlights its potential therapeutic role in the management of AD.
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Affiliation(s)
- Dandan Geng
- Department of Human Anatomy, Hebei Medical University, Shijiazhuang 050017, Hebei, PR China
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102
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Piccinni A, Origlia N, Veltri A, Vizzaccaro C, Marazziti D, Vanelli F, Moroni I, Domenici L, Dell'Osso L. Neurodegeneration, β-amyloid and mood disorders: state of the art and future perspectives. Int J Geriatr Psychiatry 2013; 28:661-71. [PMID: 22996674 DOI: 10.1002/gps.3879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 08/02/2012] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Depression may increase the risk of developing Alzheimer's disease (AD). Recent studies have shown modifications in blood beta-amyloid (Aβ) levels in depressed patients. This literature review examines the potential relationship between Aβ-mediated neurotoxicity and pathophysiology of mood disorders. DESIGN We conducted a review of the literature focusing on recent studies reporting alterations of plasma and serum Aβ peptides levels in patients suffering from mood disorders. RESULTS Different data suggest that patients with mood disorders are at great risk of developing cognitive impairment and dementia. In particular, low plasma levels of Aβ42 peptide and a high Aβ40/Aβ42 ratio have been found in depressed patients. In addition, changes in Aβ protein levels in patients with mood disorders have been associated with the severity of cognitive impairment and correlated positively with the number of episodes and severity of illness course. CONCLUSIONS Given the intriguing association between change in plasma level of Aβ, depression and cognitive impairment, future work should focus on the relationship between Aβ peripheral level(s), biomarkers of neurodegeneration and development of dementia in patients affected by mood disorders.
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Affiliation(s)
- Armando Piccinni
- Department of Psychiatry, Neurobiology, Pharmacology and Biotechnology, University of Pisa, Pisa, Italy.
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103
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Shastri A, Bonifati DM, Kishore U. Innate immunity and neuroinflammation. Mediators Inflamm 2013; 2013:342931. [PMID: 23843682 PMCID: PMC3697414 DOI: 10.1155/2013/342931] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2013] [Accepted: 05/15/2013] [Indexed: 01/07/2023] Open
Abstract
Inflammation of central nervous system (CNS) is usually associated with trauma and infection. Neuroinflammation occurs in close relation to trauma, infection, and neurodegenerative diseases. Low-level neuroinflammation is considered to have beneficial effects whereas chronic neuroinflammation can be harmful. Innate immune system consisting of pattern-recognition receptors, macrophages, and complement system plays a key role in CNS homeostasis following injury and infection. Here, we discuss how innate immune components can also contribute to neuroinflammation and neurodegeneration.
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Affiliation(s)
- Abhishek Shastri
- Centre for Infection, Immunity and Disease Mechanisms, Heinz Wolff Building, Brunel University, London UB8 3PH, UK
| | - Domenico Marco Bonifati
- Unit of Neurology, Department of Neurological Disorders, Santa Chiara Hospital, Largo Medaglie d'oro 1, 38100 Trento, Italy
| | - Uday Kishore
- Centre for Infection, Immunity and Disease Mechanisms, Heinz Wolff Building, Brunel University, London UB8 3PH, UK
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104
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Li XH, Du LL, Cheng XS, Jiang X, Zhang Y, Lv BL, Liu R, Wang JZ, Zhou XW. Glycation exacerbates the neuronal toxicity of β-amyloid. Cell Death Dis 2013; 4:e673. [PMID: 23764854 PMCID: PMC3698547 DOI: 10.1038/cddis.2013.180] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Accumulation evidence shows that β-amyloid (Aβ) is a neurotoxic and accumulation of Aβ is responsible for the pathology of Alzheimer's disease (AD). However, it is currently not fully understood what makes Aβ toxic and accumulated. Previous studies demonstrate that Aβ is a suitable substrate for glycation, producing one form of the advanced glycation endproducts (AGEs). We speculated that Aβ-AGE formation may exacerbate the neurotoxicity. To explore whether the Aβ-AGE is more toxic than the authentic Aβ and to understand the molecular mechanisms, we synthesized glycated Aβ by incubating Aβ with methylglyoxal (MG) in vitro and identified the formation of glycated Aβ by fluorescence spectrophotometer. Then, we treated the primary hippocampal neurons cultured 8 days in vitro with Aβ-AGE or Aβ for 24 h. We observed that glycation exacerbated neurotoxicity of Aβ with upregulation of receptor for AGE (RAGE) and activation of glycogen synthase kinase-3 (GSK-3), whereas simultaneous application of RAGE antibody or GSK-3 inhibitor reversed the neuronal damages aggravated by glycated Aβ. Thereafter, we found that Aβ is also glycated with an age-dependent elevation of AGEs in Tg2576 mice, whereas inhibition of Aβ-AGE formation by subcutaneously infusion of aminoguanidine for 3 months significantly rescued the early cognitive deficit in mice. Our data reveal for the first time that the glycated Aβ is more toxic. We propose that the glycated Aβ with the altered secondary structure may be a more suitable ligand than Aβ for RAGE and subsequent activation of GSK-3 that can lead to cascade pathologies of AD, therefore glycated Aβ may be a new therapeutic target for AD.
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Affiliation(s)
- X-H Li
- Department of Pathophysiology, Key Laboratory of Neurological Diseases of Ministry of Education, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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105
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Centaurin-α1-Ras-Elk-1 signaling at mitochondria mediates β-amyloid-induced synaptic dysfunction. J Neurosci 2013; 33:5367-74. [PMID: 23516302 DOI: 10.1523/jneurosci.2641-12.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Alzheimer's disease is thought to be caused by β-amyloid peptide (Aβ)-dependent synaptic dysfunction. However, the signaling pathways connecting Aβ and synaptic dysfunction remain elusive. Here we report that Aβ transiently increases the expression level of centaurin-α1 (CentA1) in neurons, which induces a Ras-dependent association of Elk-1 with mitochondria, leading to mitochondrial and synaptic dysfunction in organotypic hippocampal slices of rats. Downregulation of the CentA1-Ras-Elk-1 pathway restored normal mitochondrial activity, spine structural plasticity, spine density, and the amplitude and frequency of miniature EPSCs in Aβ-treated neurons, whereas upregulation of the pathway was sufficient to decrease spine density. Elevations of CentA1 and association of Elk-1 with mitochondria were also observed in transgenic mice overexpressing a human mutant form of amyloid precursor protein. Therefore, the CentA1-Ras-Elk-1 signaling pathway acts on mitochondria to regulate dendritic spine density and synaptic plasticity in response to Aβ in hippocampal neurons, providing new pharmacological targets for Alzheimer's disease.
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106
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Brain-derived neurotrophic factor-dependent synaptic plasticity is suppressed by interleukin-1β via p38 mitogen-activated protein kinase. J Neurosci 2013; 32:17714-24. [PMID: 23223292 DOI: 10.1523/jneurosci.1253-12.2012] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Evolving evidence suggests that brain inflammation and the buildup of proinflammatory cytokine increases the risk for cognitive decline and cognitive dysfunction. Interleukin-1β (IL-1β), acting via poorly understood mechanisms, appears to be a key cytokine in causing these deleterious effects along with a presumably related loss of long-term potentiation (LTP)-type synaptic plasticity. We hypothesized that IL-1β disrupts brain-derived neurotrophic factor (BDNF) signaling cascades and thereby impairs the formation of filamentous actin (F-actin) in dendritic spines, an event that is essential for the stabilization of LTP. Actin polymerization in spines requires phosphorylation of the filament severing protein cofilin and is modulated by expression of the immediate early gene product Arc. Using rat organotypic hippocampal cultures, we found that IL-1β suppressed BDNF-dependent regulation of Arc and phosphorylation of cofilin and cAMP response element-binding protein (CREB), a transcription factor regulating Arc expression. IL-1β appears to act on BDNF signal transduction by impairing the phosphorylation of insulin receptor substrate 1, a protein that couples activation of the BDNF receptor TrkB to downstream signaling pathways regulating CREB, Arc, and cofilin. IL-1β upregulated p38 mitogen-activated protein kinase (MAPK), and inhibiting p38 MAPK prevented IL-1β from disrupting BDNF signaling. IL-1β also prevented the formation of F-actin in spines and impaired the consolidation, but not the induction, of BDNF-dependent LTP in acute hippocampal slices. The suppressive effect of IL-1β on F-actin and LTP was prevented by inhibiting p38 MAPK. These findings define a new mechanism for the action of IL-1β on LTP and point to a potential therapeutic target to restore synaptic plasticity.
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107
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Abstract
RAGE is a key molecule in the onset and sustainment of the inflammatory response. New studies indicate that RAGE might represent a new link between the innate and adaptive immune system. RAGE belongs to the superfamily of Ig cell-surface receptors and is expressed on all types of leukocytes promoting activation, migration, or maturation of the different cells. RAGE expression is prominent on the activated endothelium, where it mediates leukocyte adhesion and transmigration. Moreover, proinflammatory molecules released from the inflamed or injured vascular system induce migration and proliferation of SMCs. RAGE binds a large number of different ligands and is therefore considered as a PRR, recognizing a structural motif rather than a specific ligand. In this review, we summarize the current knowledge about the signaling pathways activated in the different cell types and discuss a potential activation mechanism of RAGE, as well as putative options for therapeutic intervention.
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Affiliation(s)
- Katrin Kierdorf
- Department of Neuropathology, University of Freiburg, Freiburg, Germany
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108
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Iori V, Maroso M, Rizzi M, Iyer AM, Vertemara R, Carli M, Agresti A, Antonelli A, Bianchi ME, Aronica E, Ravizza T, Vezzani A. Receptor for Advanced Glycation Endproducts is upregulated in temporal lobe epilepsy and contributes to experimental seizures. Neurobiol Dis 2013; 58:102-14. [PMID: 23523633 DOI: 10.1016/j.nbd.2013.03.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/05/2013] [Accepted: 03/13/2013] [Indexed: 01/07/2023] Open
Abstract
Toll-like receptor 4 (TLR4) activation in neuron and astrocytes by High Mobility Group Box 1 (HMGB1) protein is a key mechanism of seizure generation. HMGB1 also activates the Receptor for Advanced Glycation Endproducts (RAGE), but it was unknown whether RAGE activation contributes to seizures or to HMGB1 proictogenic effects. We found that acute EEG seizures induced by 7ng intrahippocampal kainic acid (KA) were significantly reduced in Rage-/- mice relative to wild type (Wt) mice. The proictogenic effect of HMGB1 was decreased in Rage-/- mice, but less so, than in Tlr4-/- mice. In a mouse mesial temporal lobe epilepsy (mTLE) model, status epilepticus induced by 200ng intrahippocampal KA and the onset of the spontaneous epileptic activity were similar in Rage-/-, Tlr4-/- and Wt mice. However, the number of hippocampal paroxysmal episodes and their duration were both decreased in epileptic Rage-/- and Tlr4-/- mice vs Wt mice. All strains of epileptic mice displayed similar cognitive deficits in the novel object recognition test vs the corresponding control mice. CA1 neuronal cell loss was increased in epileptic Rage-/- vs epileptic Wt mice, while granule cell dispersion and doublecortin (DCX)-positive neurons were similarly affected. Notably, DCX neurons were preserved in epileptic Tlr4-/- mice. We did not find compensatory changes in HMGB1-related inflammatory signaling nor in glutamate receptor subunits in Rage-/- and Tlr4-/- naïve mice, except for ~20% NR2B subunit reduction in Rage-/- mice. RAGE was induced in neurons, astrocytes and microvessels in human and experimental mTLE hippocampi. We conclude that RAGE contributes to hyperexcitability underlying acute and chronic seizures, as well as to the proictogenic effects of HMGB1. RAGE and TLR4 play different roles in the neuropathologic sequelae developing after status epilepticus. These findings reveal new molecular mechanisms underlying seizures, cell loss and neurogenesis which involve inflammatory pathways upregulated in human epilepsy.
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Affiliation(s)
- Valentina Iori
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri, Milan, Italy
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109
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Zhang J, Zhen YF, Pu-Bu-Ci-Ren, Song LG, Kong WN, Shao TM, Li X, Chai XQ. Salidroside attenuates beta amyloid-induced cognitive deficits via modulating oxidative stress and inflammatory mediators in rat hippocampus. Behav Brain Res 2013; 244:70-81. [PMID: 23396166 DOI: 10.1016/j.bbr.2013.01.037] [Citation(s) in RCA: 110] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 01/27/2013] [Accepted: 01/28/2013] [Indexed: 01/14/2023]
Abstract
Beta amyloid (Aβ)-induced oxidative stress and chronic inflammation in the brain are considered to be responsible for the pathogenesis of Alzheimer's disease (AD). Salidroside, the major active ingredient of Rhodiola crenulata, has been previously shown to have antioxidant and neuroprotective properties in vitro. The present study aimed to investigate the protective effects of salidroside on Aβ-induced cognitive impairment in vivo. Rats received intrahippocampal Aβ1-40 injection were treated with salidroside (25, 50 and 75 mg/kg p.o.) once daily for 21 days. Learning and memory performance were assessed in the Morris water maze (days 17-21). After behavioral testing, the rats were sacrificed and hippocampi were removed for biochemical assays (reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GPx), malondialdehyde (MDA), acetylcholinesterase (AChE), acetylcholine (ACh)) and molecular biological analysis (Cu/Zn-SOD, Mn-SOD, GPx, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, nuclear factor κB (NF-κB), inhibitor of κB-alpha (IκBα), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), receptor for advanced glycation end products (RAGE)). Our results confirmed that Aβ1-40 peptide caused learning and memory deficits in rats. Further analysis demonstrated that the NADPH oxidase-mediated oxidative stress was increased in Aβ1-40-injected rats. Furthermore, NF-κB was demonstrated to be activated in Aβ1-40-injected rats, and the COX-2, iNOS and RAGE expression were also induced by Aβ1-40. However, salidroside (50 and 75 mg/kg p.o.) reversed all the former alterations. Thus, the study indicates that salidroside may have a protective effect against AD via modulating oxidative stress and inflammatory mediators.
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Affiliation(s)
- Jia Zhang
- Department of Neurology, The First Affiliated Hospital of Hebei Medical University, Shijiazhuang 050017, China.
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110
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Zhao L, Wang JL, Wang YR, Fa XZ. Apigenin attenuates copper-mediated β-amyloid neurotoxicity through antioxidation, mitochondrion protection and MAPK signal inactivation in an AD cell model. Brain Res 2012. [PMID: 23178511 DOI: 10.1016/j.brainres.2012.11.019] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Apigenin, belonging to a less toxic and non-mutagenic flavone subclass of flavonoids, has been reported to possess numerous biological activities beneficial to health. Although evidence has shown apigenin might exert its protective effects by reducing the toxicity induced by amyloid-β peptides (Aβ), the precise mechanism is unclear. In the present study, we investigated the in vitro neuroprotective activity of apigenin interrelated with amyloid toxicity and mental homeostasis in an Alzheimer's disease (AD) cell model and explored its potential signal transduction. Our results showed that apigenin protected neurons against Aβ-mediated toxicity induced by copper, which was characterized by increasing neuronal viability and relieving mitochondrial membrane dissipation and neuronal nuclear condensation. Further, we demonstrated that apigenin did not provide sufficient effect on decreasing β-amyloid precursor protein (AβPP) expression and lowering Aβ(1-42) secretion, but conserved redox balance by increasing intracellular glutathione levels and enhancing cellular superoxide dismutase and glutathione peroxidase activities, reduced intracellular reactive oxygen species (ROS) generation, blocked ROS-induced p38 mitogen-activated protein kinases (p38 MAPK)- MAPKAP kinase-2 (MK2)-heat shock protein 27 (Hsp27) and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)-c-Jun signaling pathways, preserved mitochondrial function, and then regulated apoptotic pathways. In conclusion, apigenin could exert neuroprotection against Aβ-induced toxicity in the presence of copper mainly through the mechanisms that regulate redox imbalance, preserve mitochondrial function, inhibit MAPK pathways, and depress neuronal apoptosis.
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Affiliation(s)
- Le Zhao
- College of Life and Environmental Sciences, Minzu University of China, 27 South Street, Zhongguancun Beijing 100081, PR China
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111
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Liu R, Wu CX, Zhou D, Yang F, Tian S, Zhang L, Zhang TT, Du GH. Pinocembrin protects against β-amyloid-induced toxicity in neurons through inhibiting receptor for advanced glycation end products (RAGE)-independent signaling pathways and regulating mitochondrion-mediated apoptosis. BMC Med 2012; 10:105. [PMID: 22989295 PMCID: PMC3542580 DOI: 10.1186/1741-7015-10-105] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 09/18/2012] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND It is known that amyloid-β peptide (Aβ) plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). Interaction between Aβ and the receptor for advanced glycation end products (RAGE) has been implicated in neuronal degeneration associated with this disease. Pinocembrin, a flavonoid abundant in propolis, has been reported to possess numerous biological activities beneficial to health. Our previous studies have demonstrated that pinocembrin has neuroprotective effects on ischemic and vascular dementia in animal models. It has been approved by the State Food and Drug Administration of China for clinical use in stroke patients. Against this background, we investigated the effects of pinocembrin on cognitive function and neuronal protection against Aβ-induced toxicity and explored its potential mechanism. METHODS Mice received an intracerebroventricular fusion of Aβ25-35. Pinocembrin was administrated orally at 20 mg/kg/day and 40 mg/kg/day for 8 days. Behavioral performance, cerebral cortex neuropil ultrastructure, neuronal degeneration and RAGE expression were assessed. Further, a RAGE-overexpressing cell model and an AD cell model were used for investigating the mechanisms of pinocembrin. The mechanisms underlying the efficacy of pinocembrin were conducted on target action, mitochondrial function and potential signal transduction using fluorescence-based multiparametric technologies on a high-content analysis platform. RESULTS Our results showed that oral administration of pinocembrin improved cognitive function, preserved the ultrastructural neuropil and decreased neurodegeneration of the cerebral cortex in Aβ25-35-treated mice. Pinocembrin did not have a significant effect on inhibiting Aβ1-42 production and scavenging intracellular reactive oxygen species (ROS). However, pinocembrin significantly inhibited the upregulation of RAGE transcripts and protein expression both in vivo and in vitro, and also markedly depressed the activation of p38 mitogen-activated protein kinase (MAPK)-MAPKAP kinase-2 (MK2)-heat shock protein 27 (HSP27) and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK)-c-Jun pathways and the downstream nuclear factor κB (NFκB) inflammatory response subsequent to Aβ-RAGE interaction. In addition, pinocembrin significantly alleviated mitochondrial dysfunction through improving mitochondrial membrane potential and inhibiting mitochondrial oxidative stress, and regulated mitochondrion-mediated apoptosis by restoration of B cell lymphoma 2 (Bcl-2) and cytochrome c and inactivation of caspase 3 and caspase 9. CONCLUSIONS Pinocembrin was shown to infer cognitive improvement and neuronal protection in AD models. The mechanisms of action of the compound were illustrated on RAGE-dependent transduction inhibition and mitochondrion protection. It appears to be a promising candidate for the prevention and therapy of AD.
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Affiliation(s)
- Rui Liu
- National Center of Pharmacological Screening, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100050, PR China
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112
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Mitochondria-specific accumulation of amyloid β induces mitochondrial dysfunction leading to apoptotic cell death. PLoS One 2012; 7:e34929. [PMID: 22514691 PMCID: PMC3325919 DOI: 10.1371/journal.pone.0034929] [Citation(s) in RCA: 184] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Accepted: 03/07/2012] [Indexed: 12/30/2022] Open
Abstract
Mitochondria are best known as the essential intracellular organelles that host the homeostasis required for cellular survival, but they also have relevance in diverse disease-related conditions, including Alzheimer's disease (AD). Amyloid β (Aβ) peptide is the key molecule in AD pathogenesis, and has been highlighted in the implication of mitochondrial abnormality during the disease progress. Neuronal exposure to Aβ impairs mitochondrial dynamics and function. Furthermore, mitochondrial Aβ accumulation has been detected in the AD brain. However, the underlying mechanism of how Aβ affects mitochondrial function remains uncertain, and it is questionable whether mitochondrial Aβ accumulation followed by mitochondrial dysfunction leads directly to neuronal toxicity. This study demonstrated that an exogenous Aβ1–42 treatment, when applied to the hippocampal cell line of mice (specifically HT22 cells), caused a deleterious alteration in mitochondria in both morphology and function. A clathrin-mediated endocytosis blocker rescued the exogenous Aβ1–42-mediated mitochondrial dysfunction. Furthermore, the mitochondria-targeted accumulation of Aβ1–42 in HT22 cells using Aβ1–42 with a mitochondria-targeting sequence induced the identical morphological alteration of mitochondria as that observed in the APP/PS AD mouse model and exogenous Aβ1–42-treated HT22 cells. In addition, subsequent mitochondrial dysfunctions were demonstrated in the mitochondria-specific Aβ1–42 accumulation model, which proved indistinguishable from the mitochondrial impairment induced by exogenous Aβ1–42-treated HT22 cells. Finally, cellular toxicity was directly induced by mitochondria-targeted Aβ1–42 accumulation, which mimics the apoptosis process in exogenous Aβ1–42-treated HT22 cells. Taken together, these results indicate that mitochondria-targeted Aβ1–42 accumulation is the necessary and sufficient condition for Aβ-mediated mitochondria impairments, and leads directly to cellular death rather than along with other Aβ-mediated signaling alterations.
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113
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The Complexity of Sporadic Alzheimer's Disease Pathogenesis: The Role of RAGE as Therapeutic Target to Promote Neuroprotection by Inhibiting Neurovascular Dysfunction. Int J Alzheimers Dis 2012; 2012:734956. [PMID: 22482078 PMCID: PMC3310161 DOI: 10.1155/2012/734956] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Accepted: 12/02/2011] [Indexed: 01/08/2023] Open
Abstract
Alzheimer's disease (AD) is the most common cause of dementia. Amyloid plaques and neurofibrillary tangles are prominent pathological features of AD. Aging and age-dependent oxidative stress are the major nongenetic risk factors for AD. The beta-amyloid peptide (Aβ), the major component of plaques, and advanced glycation end products (AGEs) are key activators of plaque-associated cellular dysfunction. Aβ and AGEs bind to the receptor for AGEs (RAGE), which transmits the signal from RAGE via redox-sensitive pathways to nuclear factor kappa-B (NF-κB). RAGE-mediated signaling is an important contributor to neurodegeneration in AD. We will summarize the current knowledge and ongoing studies on RAGE function in AD. We will also present evidence for a novel pathway induced by RAGE in AD, which leads to the expression of thioredoxin interacting protein (TXNIP), providing further evidence that pharmacological inhibition of RAGE will promote neuroprotection by blocking neurovascular dysfunction in AD.
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114
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Stimulation-dependent intraspinal microtubules and synaptic failure in Alzheimer's disease: a review. Int J Alzheimers Dis 2012; 2012:519682. [PMID: 22482073 PMCID: PMC3310171 DOI: 10.1155/2012/519682] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 11/22/2011] [Indexed: 01/13/2023] Open
Abstract
There are many microtubules in axons and dendritic shafts, but it has been thought that there were fewer microtubules in spines. Recently, there have been four reports that observed the intraspinal microtubules. Because microtubules originate from the centrosome, these four reports strongly suggest a stimulation-dependent connection between the nucleus and the stimulated postsynaptic membrane by microtubules. In contrast, several pieces of evidence suggest that spine elongation may be caused by the polymerization of intraspinal microtubules. This structural mechanism for spine elongation suggests, conversely, that the synapse loss or spine loss observed in Alzheimer's disease may be caused by the depolymerization of intraspinal microtubules. Based on this evidence, it is suggested that the impairment of intraspinal microtubules may cause spinal structural change and block the translocation of plasticity-related molecules between the stimulated postsynaptic membranes and the nucleus, resulting in the cognitive deficits of Alzheimer's disease.
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115
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Wu CL, Yin JH, Hwang CS, Chen SD, Yang DY, Yang DI. c-Jun-dependent sulfiredoxin induction mediates BDNF protection against mitochondrial inhibition in rat cortical neurons. Neurobiol Dis 2012; 46:450-62. [PMID: 22402332 DOI: 10.1016/j.nbd.2012.02.010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Revised: 01/20/2012] [Accepted: 02/20/2012] [Indexed: 01/19/2023] Open
Abstract
In current study, we tested the hypothesis that c-Jun-dependent sulfiredoxin expression mediates protective effects of brain-derived neurotrophic factor (BDNF) against neurotoxicity induced by 3-nitropropionic acid (3-NP), a mitochondrial complex II inhibitor, in primary rat cortical cultures. We found that BDNF-dependent c-Jun expression and nuclear translocation required prior phosphorylation of extracellular signal-regulated kinase (ERK)1/2, but not Akt. BDNF also transiently activated the expression of sulfiredoxin, an ATP-dependent antioxidant enzyme, at both mRNA and protein levels. Furthermore, both c-Jun siRNA and ERK1/2 inhibitor PD98059 suppressed BDNF-induced sulfiredoxin expression. Finally, PD98059, c-Jun siRNA, and sulfiredoxin siRNA all abrogated BDNF-mediated 3-NP resistance. Together, these results established a signaling cascade of "BDNF → ERK1/2-Pi → c-Jun → sulfiredoxin → 3-NP resistance". We therefore conclude that c-Jun-induced sulfiredoxin mediates the BDNF-dependent neuroprotective effects against 3-NP toxicity in primary rat cortical neurons, at least in part.
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Affiliation(s)
- Chia-Lin Wu
- Program in Molecular Medicine, National Yang-Ming University and Academia Sinica, Taipei, Taiwan
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116
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Nomura I, Takechi H, Kato N. Intraneuronally injected amyloid β inhibits long-term potentiation in rat hippocampal slices. J Neurophysiol 2012; 107:2526-31. [PMID: 22338026 DOI: 10.1152/jn.00589.2011] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Extracellular accumulation of amyloid beta (Aβ) is a hallmark of Alzheimer's disease (AD). It has been reported that extracellular perfusion of Aβ inhibits long-term potentiation (LTP), which is strongly related to memory in animal models. However, it has recently been proposed that intracellular Aβ may be the first pathological change to occur in AD. Here, we have investigated the effect on LTP of intracellular injection of Aβ (Aβ(1-40), Aβ(1-42)) into hippocampal pyramidal cells using patch-clamp technique. We found that injection of 1 nM Aβ(1-42) completely blocked LTP, and extracellular perfusion of a p38 MAPK inhibitor or a metabotropic glutamate receptor blocker reversed these blocking effects on LTP. Furthermore, we have examined the effects of different concentrations of Aβ(1-40) and Aβ(1-42) on LTP and showed that Aβ(1-40) required a 1,000-fold higher concentration to attenuate LTP than 1 nM Aβ(1-42). These results indicate that LTP is impaired by Aβ injected into genetically wild-type neurons in the sliced hippocampus, suggesting an acute action of intracellular Aβ on the intracellular LTP-inducing machinery.
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Affiliation(s)
- Izumi Nomura
- Department of Geriatric Medicine, Graduate School of Medicine, Kyoto University, 54 Shogoin, Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan
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117
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Neuronal receptors as targets for the action of amyloid-beta protein (Aβ) in the brain. Expert Rev Mol Med 2012; 14:e2. [PMID: 22261393 DOI: 10.1017/s1462399411002134] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Accumulation of neurotoxic soluble amyloid-beta protein (Aβ) oligomers in the brains of patients with Alzheimer disease (AD) and their role in AD pathogenesis have emerged as topics of considerable interest in recent years. Soluble Aβ oligomers impair synaptic and neuronal function, leading to neurodegeneration that is clinically manifested by memory and cognitive dysfunction. The precise mechanisms whereby Aβ oligomers cause neurotoxicity remain unknown. Emerging insights into the mechanistic link between neuronal receptors and soluble Aβ oligomers highlight the potential role of these receptors in Aβ-mediated neurotoxicity in AD. The current review focuses on studies describing interactions between soluble Aβ oligomers and neuronal receptors, and their role in AD pathogenesis. Furthermore, these studies provide insight into potential therapies for AD using compounds directed at putative target receptors for the action of Aβ in the central nervous system. We focus on interactions of Aβ with subtypes of acetylcholine and glutamatergic receptors. Additionally, neuronal receptors such as insulin, amylin and receptor for advanced glycation end products could be potential targets for soluble Aβ-oligomer-mediated neurotoxicity. Aβ interactions with other receptors such as the p75 neurotrophin receptors, which are highly expressed on cholinergic basal forebrain neurons lost in AD, are also highlighted.
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118
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Correia SC, Santos RX, Carvalho C, Cardoso S, Candeias E, Santos MS, Oliveira CR, Moreira PI. Insulin signaling, glucose metabolism and mitochondria: major players in Alzheimer's disease and diabetes interrelation. Brain Res 2012; 1441:64-78. [PMID: 22290178 DOI: 10.1016/j.brainres.2011.12.063] [Citation(s) in RCA: 133] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 11/07/2011] [Accepted: 12/31/2011] [Indexed: 12/24/2022]
Abstract
Many epidemiological studies have shown that diabetes, particularly type 2 diabetes, significantly increases the risk to develop Alzheimer's disease. Both diseases share several common abnormalities including impaired glucose metabolism, increased oxidative stress, insulin resistance and deposition of amyloidogenic proteins. It has been suggested that these two diseases disrupt common cellular and molecular pathways and each disease potentiates the progression of the other. This review discusses clinical and biochemical features shared by Alzheimer's disease and diabetes, giving special attention to the involvement of insulin signaling, glucose metabolism and mitochondria. Understanding the key mechanisms underlying this deleterious interaction may provide opportunities for the design of effective therapeutic strategies.
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Affiliation(s)
- Sónia C Correia
- Center for Neuroscience and Cell Biology, University of Coimbra, 3000-354 Coimbra, Portugal
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119
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Yan SS, Chen D, Yan S, Guo L, Du H, Chen JX. RAGE is a key cellular target for Abeta-induced perturbation in Alzheimer's disease. Front Biosci (Schol Ed) 2012. [PMID: 22202057 DOI: 10.2741/265] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
RAGE, a receptor for advanced glycation endproducts, is an immunoglobulin-like cell surface receptor that is often described as a pattern recognition receptor due to the structural heterogeneity of its ligand. RAGE is an important cellular cofactor for amyloid beta-peptide (Abeta)-mediated cellular perturbation relevant to the pathogenesis of Alzheimer's disease (AD). The interaction of RAGE with Abeta in neurons, microglia, and vascular cells accelerates and amplifies deleterious effects on neuronal and synaptic function. RAGE-dependent signaling contributes to Abeta-mediated amyloid pathology and cognitive dysfunction observed in the AD mouse model. Blockade of RAGE significantly attenuates neuronal and synaptic injury. In this review, we summarize the role of RAGE in the pathogenesis of AD, specifically in Abeta-induced cellular perturbation.
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Affiliation(s)
- Shirley ShiDu Yan
- Department of Surgery, Physicians and Surgeons College of Columbia University, New York, NY 10032, USA.
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120
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Yan SS, Chen D, Yan S, Guo L, Du H, Chen JX. RAGE is a key cellular target for Abeta-induced perturbation in Alzheimer's disease. Front Biosci (Schol Ed) 2012; 4:240-250. [PMID: 22202057 PMCID: PMC3687351 DOI: 10.2741/s265] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
RAGE, a receptor for advanced glycation endproducts, is an immunoglobulin-like cell surface receptor that is often described as a pattern recognition receptor due to the structural heterogeneity of its ligand. RAGE is an important cellular cofactor for amyloid beta-peptide (Abeta)-mediated cellular perturbation relevant to the pathogenesis of Alzheimer's disease (AD). The interaction of RAGE with Abeta in neurons, microglia, and vascular cells accelerates and amplifies deleterious effects on neuronal and synaptic function. RAGE-dependent signaling contributes to Abeta-mediated amyloid pathology and cognitive dysfunction observed in the AD mouse model. Blockade of RAGE significantly attenuates neuronal and synaptic injury. In this review, we summarize the role of RAGE in the pathogenesis of AD, specifically in Abeta-induced cellular perturbation.
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Affiliation(s)
- Shirley ShiDu Yan
- Department of Surgery, Physicians and Surgeons College of Columbia University, New York, NY 10032, USA.
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121
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Abstract
For nearly 100 years following the first description of this neurological disorder by Dr Alois Alzheimer, amyloid plaques and neurofibrillary tangles have been hypothesized to cause neuronal loss. With evidence that the extent of insoluble, deposited amyloid poorly correlated with cognitive impairment, research efforts focused on soluble forms of Aβ, also referred as Aβ oligomers. Following a decade of studies, soluble oligomeric forms of Aβ are now believed to induce the deleterious cascade(s) involved in the pathophysiology of Alzheimer's disease. In this review, we will discuss our current understanding about endogenous oligomeric Aβ production, their relative toxicity in vivo and in vitro, and explore the potential future directions needed for the field.
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Affiliation(s)
- Megan E Larson
- Departments of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sylvain E Lesné
- Departments of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA.,N. Bud Grossman Center for Memory Research and Care, University of Minnesota, Minneapolis, Minnesota, USA.,Institute for Translational Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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122
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Lee ST, Chu K, Park JE, Jung KH, Jeon D, Lim JY, Lee SK, Kim M, Roh JK. Erythropoietin improves memory function with reducing endothelial dysfunction and amyloid-beta burden in Alzheimer's disease models. J Neurochem 2011; 120:115-24. [PMID: 22004348 DOI: 10.1111/j.1471-4159.2011.07534.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Neurovascular degeneration contributes to the pathogenesis of Alzheimer's disease (AD). Because erythropoietin (EPO) promotes endothelial regeneration, we investigated the therapeutic effects of EPO in animal models of AD. In aged Tg2576 mice, EPO receptors (EPORs) were expressed in the cortex and hippocampus. Tg2576 mice were treated with daily injection of EPO (5000 IU/kg/day) for 5 days. At 14 days, EPO improved contextual memory as measured by fear-conditioning test. EPO enhanced endothelial proliferation and the level of synaptophysin expression in the brain. EPO also increased capillary density, and decreased the level of the receptor for advanced glycation endproducts (RAGE) in the brain, while decreasing in the amount of amyloid plaque and amyloid-β (Aβ). In cultured human endothelial cells, EPO enhanced angiogenesis and suppressed the expression of the RAGE. These results show that EPO improves memory and ameliorates endothelial degeneration induced by Aβ in AD models. This pre-clinical evidence suggests that EPO may be useful for the treatment of AD.
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Affiliation(s)
- Soon-Tae Lee
- Department of Neurology, Seoul National University Hospital, Seoul, South Korea
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123
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Nonfibrillar Abeta 1-42 inhibits glutamate uptake and phosphorylates p38 in human fibroblasts. Alzheimer Dis Assoc Disord 2011; 25:164-72. [PMID: 20921877 DOI: 10.1097/wad.0b013e3181f9860f] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Alzheimer disease (AD) is the most prevalent neurodegenerative disease, characterized by an increased deposition of β-amyloid (Abeta) within the central nervous system, leading to neuronal death. The availability of effective models, in which confirming novel pathogenic hypotheses and developing therapeutic targets, represents a very important goal for the field of AD. Fibroblasts from these patients may be relevant models in which addressing these issues, as they display biochemical alterations mirroring SNC ones. In this work, fibroblasts obtained from controls were studied after exposure to nonfibrillar Abeta 1-42, showing decreased glutamate uptake, similar to that observed in AD cells, in absence of transporters modifications. Nonfibrillar Abeta 1-42 was able to induce in control cells mitochondrial alterations and p38-phosphorylation, mirroring similar alterations found in AD fibroblasts. Under our experimental conditions, this treatment induced neither apoptosis nor necrosis. To investigate a putative role of p38-modulation in mediating nonfibrillar Abeta 1-42 toxicity, fibroblasts from controls were pretreated with retinoic-acid, and SB203580, a p38-inhibitor. These pretreatments prevented both p38-phosphorylation and glutamate uptake inhibition. Our results suggest that nonfibrillar Abeta 1-42 downregulates glutamate transporters activity interfering with p38-activation and mitochondrial stress. Thus, modulating complex kinase signaling pathway might represent a future therapeutic target in AD.
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124
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Manzoni C, Colombo L, Bigini P, Diana V, Cagnotto A, Messa M, Lupi M, Bonetto V, Pignataro M, Airoldi C, Sironi E, Williams A, Salmona M. The molecular assembly of amyloid aβ controls its neurotoxicity and binding to cellular proteins. PLoS One 2011; 6:e24909. [PMID: 21966382 PMCID: PMC3179491 DOI: 10.1371/journal.pone.0024909] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2011] [Accepted: 08/22/2011] [Indexed: 11/29/2022] Open
Abstract
Accumulation of β-sheet-rich peptide (Aβ) is strongly associated with Alzheimer's disease, characterized by reduction in synapse density, structural alterations of dendritic spines, modification of synaptic protein expression, loss of long-term potentiation and neuronal cell death. Aβ species are potent neurotoxins, however the molecular mechanism responsible for Aβ toxicity is still unknown. Numerous mechanisms of toxicity were proposed, although there is no agreement about their relative importance in disease pathogenesis. Here, the toxicity of Aβ 1–40 and Aβ 1–42 monomers, oligomers or fibrils, was evaluated using the N2a cell line. A structure-function relationship between peptide aggregation state and toxic properties was established. Moreover, we demonstrated that Aβ toxic species cross the plasma membrane, accumulate in cells and bind to a variety of internal proteins, especially on the cytoskeleton and in the endoplasmatic reticulum (ER). Based on these data we suggest that numerous proteins act as Aβ receptors in N2a cells, triggering a multi factorial toxicity.
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Affiliation(s)
- Claudia Manzoni
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Laura Colombo
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Paolo Bigini
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Valentina Diana
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Alfredo Cagnotto
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Massimo Messa
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Monica Lupi
- Department of Oncology, Mario Negri Institute for Pharmacological Research, Milan, Italy
| | - Valentina Bonetto
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
- Dulbecco Telethon Institute, Milan, Italy
| | - Mauro Pignataro
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
- Dulbecco Telethon Institute, Milan, Italy
| | - Cristina Airoldi
- Department. of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Erika Sironi
- Department. of Biotechnology and Bioscience, University of Milano-Bicocca, Milan, Italy
| | - Alun Williams
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Mario Salmona
- Department of Molecular Biochemistry and Pharmacology, Mario Negri Institute for Pharmacological Research, Milan, Italy
- * E-mail:
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125
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Younessi P, Yoonessi A. Advanced glycation end-products and their receptor-mediated roles: inflammation and oxidative stress. IRANIAN JOURNAL OF MEDICAL SCIENCES 2011; 36:154-66. [PMID: 23358382 PMCID: PMC3556769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/16/2010] [Revised: 12/18/2010] [Accepted: 02/20/2011] [Indexed: 11/27/2022]
Abstract
Glycation is a protein modification, which results in a change in a protein structure. Glycation is believed to be the etiology of various age-related diseases such as diabetes mellitus and Alzheimer's disease (AD). Activation of microglia and resident macrophages in the brain by glycated proteins with subsequent oxidative stress and cytokine release may be an important factor in the progression of AD. It is also suggested that interaction between an advanced glycation end product (AGE) and its receptor (RAGE) results in glial activation as well as cytokine release and reactive oxygen species release. The use of antioxidants, receptor mediated compounds and reactive oxygen species scavenging enzyme produce an opportunity to intervene with AGE-RAGE signaling pathway, and thereby to slow down the progression of aging-related diseases.
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Affiliation(s)
- Parisa Younessi
- Centre for Complementary Medicine Research, University of Western Sydney, Campbelltown Campus, Sydney, Australia
- Faculty of Applied Science, University of Canberra, Canberra, Australia
| | - Ali Yoonessi
- Department of Neuroscience, School of Advanced Medical Technologies, Tehran University of Medical Science, Tehran, Iran
- Iranian National Center for Addiction Studies, Tehran University of Medical Sciences, Tehran, Iran
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126
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Soluble Aβ oligomers inhibit long-term potentiation through a mechanism involving excessive activation of extrasynaptic NR2B-containing NMDA receptors. J Neurosci 2011; 31:6627-38. [PMID: 21543591 DOI: 10.1523/jneurosci.0203-11.2011] [Citation(s) in RCA: 474] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
In Alzheimer's disease (AD), dementia severity correlates strongly with decreased synapse density in hippocampus and cortex. Numerous studies report that hippocampal long-term potentiation (LTP) can be inhibited by soluble oligomers of amyloid β-protein (Aβ), but the synaptic elements that mediate this effect remain unclear. We examined field EPSPs and whole-cell recordings in wild-type mouse hippocampal slices. Soluble Aβ oligomers from three distinct sources (cultured cells, AD cortex, or synthetic peptide) inhibited LTP, and this was prevented by the selective NR2B inhibitors ifenprodil and Ro 25-6981. Soluble Aβ enhanced NR2B-mediated NMDA currents and extrasynaptic responses; these effects were mimicked by the glutamate reuptake inhibitor dl-threo-β-benzyloxyaspartic acid. Downstream, an Aβ-mediated rise in p38 mitogen-activated protein kinase (MAPK) activation was followed by downregulation of cAMP response element-binding protein, and LTP impairment was prevented by inhibitors of p38 MAPK or calpain. Thus, soluble Aβ oligomers at low nanomolar levels present in AD brain increase activation of extrasynaptic NR2B-containing receptors, thereby impairing synaptic plasticity.
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127
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Yamamoto K, Ueta Y, Wang L, Yamamoto R, Inoue N, Inokuchi K, Aiba A, Yonekura H, Kato N. Suppression of a neocortical potassium channel activity by intracellular amyloid-β and its rescue with Homer1a. J Neurosci 2011; 31:11100-9. [PMID: 21813671 PMCID: PMC6623357 DOI: 10.1523/jneurosci.6752-10.2011] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2010] [Revised: 04/18/2011] [Accepted: 05/22/2011] [Indexed: 11/21/2022] Open
Abstract
It is proposed that intracellular amyloid-β (Aβ), before extracellular plaque formation, triggers cognitive deficits in Alzheimer disease (AD). Here we report how intracellular Aβ affects neuronal properties. This was done by injecting Aβ protein into rat and mouse neocortical pyramidal cells through whole-cell patch pipettes and by using 3xTg AD model mice, in which intracellular Aβ is accumulated innately. In rats, intracellular application of a mixed Aβ(1-42) preparation containing both oligomers and monomers, but not a monomeric preparation of Aβ(1-40), broadened spike width and augmented Ca(2+) influx via voltage-dependent Ca(2+) channels in neocortical neurons. Both effects were mimicked and occluded by charybdotoxin, a blocker of large-conductance Ca(2+)-activated K(+) (BK) channels, and blocked by isopimaric acid, a BK channel opener. Surprisingly, augmented Ca(2+) influx was caused by elongated spike duration, but not attributable to direct Ca(2+) channel modulation by Aβ(1-42). The Aβ(1-42)-induced spike broadening was blocked by electroconvulsive shock (ECS), which we previously showed to facilitate BK channel opening via expression of the scaffold protein Homer1a. In young 3xTg and wild mice, we confirmed spike broadening by Aβ(1-42), which was again mimicked and occluded by charybdotoxin and blocked by ECS. In Homer1a knock-out mice, ECS failed to block the Aβ(1-42) effect. Single-channel recording on BK channels supported these results. These findings suggest that the suppression of BK channels by intracellular Aβ(1-42) is a possible key mechanism for early dysfunction in the AD brain, which may be counteracted by activity-dependent expression of Homer1a.
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Affiliation(s)
- Kenji Yamamoto
- Departments of Physiology and
- Clinical Research Center and Department of Neurology, Utano National Hospital, Kyoto 616-8255, Japan
| | | | - Li Wang
- Departments of Physiology and
- China-Japan Friendship Hospital, Beijing 100029, China
| | | | - Naoko Inoue
- Mitsubishi Kagaku Institute of Life Sciences, Tokyo 194-8511, Japan, and
| | - Kaoru Inokuchi
- Mitsubishi Kagaku Institute of Life Sciences, Tokyo 194-8511, Japan, and
| | - Atsu Aiba
- Department of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan
| | - Hideto Yonekura
- Biochemistry, Kanazawa Medical University, Ishikawa 920-0293, Japan
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Bachstetter AD, Xing B, de Almeida L, Dimayuga ER, Watterson DM, Van Eldik LJ. Microglial p38α MAPK is a key regulator of proinflammatory cytokine up-regulation induced by toll-like receptor (TLR) ligands or beta-amyloid (Aβ). J Neuroinflammation 2011; 8:79. [PMID: 21733175 PMCID: PMC3142505 DOI: 10.1186/1742-2094-8-79] [Citation(s) in RCA: 183] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 07/06/2011] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Overproduction of proinflammatory cytokines from activated microglia has been implicated as an important contributor to pathophysiology progression in both acute and chronic neurodegenerative diseases. Therefore, it is critical to elucidate intracellular signaling pathways that are significant contributors to cytokine overproduction in microglia exposed to specific stressors, especially pathways amenable to drug interventions. The serine/threonine protein kinase p38α MAPK is a key enzyme in the parallel and convergent intracellular signaling pathways involved in stressor-induced production of IL-1β and TNFα in peripheral tissues, and is a drug development target for peripheral inflammatory diseases. However, much less is known about the quantitative importance of microglial p38α MAPK in stressor-induced cytokine overproduction, or the potential of microglial p38α MAPK to be a druggable target for CNS disorders. Therefore, we examined the contribution of microglial p38αMAPK to cytokine up-regulation, with a focus on the potential to suppress the cytokine increase by inhibition of the kinase with pharmacological or genetic approaches. METHODS The microglial cytokine response to TLR ligands 2/3/4/7/8/9 or to Aβ1-42 was tested in the presence of a CNS-penetrant p38α MAPK inhibitor, MW01-2-069A-SRM. Primary microglia from mice genetically deficient in p38α MAPK were used to further establish a linkage between microglia p38α MAPK and cytokine overproduction. The in vivo significance was determined by p38α MAPK inhibitor treatment in a LPS-induced model of acute neuroinflammation. RESULTS Increased IL-1β and TNFα production by the BV-2 microglial cell line and by primary microglia cultures was inhibited in a concentration-dependent manner by the p38α MAPK-targeted inhibitor. Cellular target engagement was demonstrated by the accompanying decrease in the phosphorylation state of two p38α MAPK protein substrates, MK2 and MSK1. Consistent with the pharmacological findings, microglia from p38α-deficient mice showed a diminished cytokine response to LPS. Further, oral administration of the inhibitor blocked the increase of IL-1β in the cerebral cortex of mice stressed by intraperitoneal injection of LPS. CONCLUSION The p38α MAPK pathway is an important contributor to the increased microglial production of proinflammatory cytokines induced by diverse stressors. The results also indicate the feasibility of targeting p38α MAPK to modulate CNS proinflammatory cytokine overproduction.
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Affiliation(s)
- Adam D Bachstetter
- Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
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129
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Binding studies of truncated variants of the Aβ peptide to the V-domain of the RAGE receptor reveal Aβ residues responsible for binding. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:592-609. [DOI: 10.1016/j.bbapap.2011.02.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 02/15/2011] [Accepted: 02/18/2011] [Indexed: 11/20/2022]
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Sambamurti K, Greig NH, Utsuki T, Barnwell EL, Sharma E, Mazell C, Bhat NR, Kindy MS, Lahiri DK, Pappolla MA. Targets for AD treatment: conflicting messages from γ-secretase inhibitors. J Neurochem 2011; 117:359-74. [PMID: 21320126 DOI: 10.1111/j.1471-4159.2011.07213.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Current evidence suggests that Alzheimer's disease (AD) is a multi-factorial disease that starts with accumulation of multiple proteins. We have previously proposed that inhibition of γ-secretase may impair membrane recycling causing neurodegeneration starting at synapses (Sambamurti K., Suram A., Venugopal C., Prakasam A., Zhou Y., Lahiri D. K. and Greig N. H. A partial failure of membrane protein turnover may cause Alzheimer's disease: a new hypothesis. Curr. Alzheimer Res., 3, 2006, 81). We also proposed familal AD mutations increase Aβ42 by inhibiting γ-secretase. Herein, we discuss the failure of Eli Lilly's γ-secretase inhibitor, semagacestat, in clinical trials in the light of our hypothesis, which extends the problem beyond toxicity of Aβ aggregates. We elaborate that γ-secretase inhibitors lead to accumulation of amyloid precursor protein C-terminal fragments that can later be processed by γ-secretase to yields bursts of Aβ to facilitate aggregation. Although we do not exclude a role for toxic Aβ aggregates, inhibition of γ-secretase can affect numerous substrates other than amyloid precursor protein to affect multiple pathways and the combined accumulation of multiple peptides in the membrane may impair its function and turnover. Taken together, protein processing and turnover pathways play an important role in maintaining cellular homeostasis and unless we clearly see consistent disease-related increase in their levels or activity, we need to focus on preserving their function rather than inhibiting them for treatment of AD and similar diseases.
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Affiliation(s)
- Kumar Sambamurti
- Department of Neuroscience, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
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132
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Han SH, Kim YH, Mook-Jung I. RAGE: the beneficial and deleterious effects by diverse mechanisms of actions. Mol Cells 2011; 31:91-7. [PMID: 21347704 PMCID: PMC3932687 DOI: 10.1007/s10059-011-0030-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 12/22/2010] [Indexed: 12/16/2022] Open
Abstract
Receptor for advanced glycation endproducts (RAGE) is a transmembrane protein that belongs to the immunoglobulin superfamily. RAGE is expressed ubiquitously-high in lung and moderate to low in a wide range of cells-in a tightly regulated manner at various stages of development. RAGE is a pattern recognition receptor that binds to multiple ligands, including amphoterin, members of the S100/calgranulin family, the integrin Mac-1, and amyloid β-peptide (Aβ). RAGE-ligand engagement effects the activation of diverse cascades that initiate and stimulate chronic stress pathways and repair, depending on the ligand, environment, and developmental stage. Further, RAGE-ligand interaction and the consequent upregulation of RAGE through a positive feedback loop are often associated with various diseases, including vascular disease, diabetes, cancer, and neurodegenerative disease. It is unknown how RAGE mediates these events, but such phenomena appear to be linked to the inflammatory response. In this review, we summarize the findings on RAGE from published reports and ongoing studies. Also, the implication of RAGE in Alzheimer disease, the most common neurodegenerative disease in the elderly population, will be discussed, with a focus on Aβ-RAGE interactions with regard to signaling pathways and their impact on cellular activity.
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Affiliation(s)
| | | | - Inhee Mook-Jung
- Department of Biochemistry and Biomedical Sciences, Seoul National University, College of Medicine, Seoul 110-799, Korea
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Bachstetter AD, Van Eldik LJ. The p38 MAP Kinase Family as Regulators of Proinflammatory Cytokine Production in Degenerative Diseases of the CNS. Aging Dis 2010; 1:199-211. [PMID: 22720195 PMCID: PMC3377763] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2010] [Revised: 09/15/2010] [Accepted: 09/17/2010] [Indexed: 06/01/2023] Open
Abstract
Inflammation in the central nervous system (CNS) is a common feature of age-related neurodegenerative diseases. Proinflammatory cytokines, such as IL-1β and TNFα, are produced primarily by cells of the innate immune system, namely microglia in the CNS, and are believed to contribute to the neuronal damage seen in the disease. The p38 mitogen-activated protein kinase (MAPK) is one of the kinase pathways that regulate the production of IL-1β and TNFα. Importantly, small molecule inhibitors of the p38 MAPK family have been developed and show efficacy in blocking the production of IL-1β and TNFα. The p38 family consists of at least four isoforms (p38α, β, γ, δ) encoded by separate genes. Recent studies have begun to demonstrate unique functions of the different isoforms, with p38α being implicated as the key isoform involved in CNS inflammation. Interestingly, there is also emerging evidence that two downstream substrates of p38 may have opposing roles, with MK2 being pro-inflammatory and MSK1/2 being antiinflammatory. This review discusses the properties, function and regulation of the p38 MAPK family as it relates to cytokine production in the CNS.
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Affiliation(s)
| | - Linda J. Van Eldik
- Sanders-Brown Center on Aging
- Dept Anatomy and Neurobiology, University of Kentucky Lexington, KY 40536-0230 USA
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134
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Microglial receptor for advanced glycation end product-dependent signal pathway drives beta-amyloid-induced synaptic depression and long-term depression impairment in entorhinal cortex. J Neurosci 2010; 30:11414-25. [PMID: 20739563 DOI: 10.1523/jneurosci.2127-10.2010] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Overproduction of beta-amyloid (Abeta) is a pathologic feature of Alzheimer's disease, leading to cognitive impairment. Here, we investigated the impact of cell-specific receptor for advanced glycation end products (RAGE) on Abeta-induced entorhinal cortex (EC) synaptic dysfunction. We found both a transient depression of basal synaptic transmission and inhibition of long-term depression (LTD) after the application of Abeta in EC slices. Synaptic depression and LTD impairment induced by Abeta were rescued by functional suppression of RAGE. Remarkably, the rescue was only observed in slices from mice expressing a defective form of RAGE targeted to microglia, but not in slices from mice expressing defective RAGE targeted to neurons. Moreover, we found that the inflammatory cytokine IL-1beta (interleukin-1beta) and stress-activated kinases [p38 MAPK (p38 mitogen-activated protein kinase) and JNK (c-Jun N-terminal kinase)] were significantly altered and involved in RAGE signaling pathways depending on RAGE expression in neuron or microglia. These findings suggest a prominent role of microglial RAGE signaling in Abeta-induced EC synaptic dysfunction.
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135
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Abstract
The development of amyloid-containing neuritic plaques is an invariable characteristic of Alzheimer's diseases (AD). The conversion from monomeric amyloid β protein (Aβ) to oligomeric Aβ and finally neuritic plaques is highly dynamic. The specific Aβ species that is correlated with disease severity remains to be discovered. Oligomeric Aβ has been detected in cultured cells, rodent and human brains, as well as human cerebrospinal fluid. Synthetic, cell, and brain derived Aβ oligomers have been found to inhibit hippocampal long-term potentiation (LTP) and this effect can be suppressed by the blockage of Aβ oligomer formation. A large body of evidence suggests that Aβ oligomers inhibit N-methyl-D-aspartate receptor dependent LTP; additional receptors have also been found to elicit downstream pathways upon binding to Aβ oligomers. Amyloid antibodies and small molecular compounds that reduce brain Aβ levels and block Aβ oligomer formation are capable of reversing synaptic dysfunction and these approaches hold a promising therapeutic potential to rescue memory disruption.
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Affiliation(s)
- Weiming Xia
- Center for Neurologic Diseases, Department of Neurology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
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136
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Sick E, Brehin S, André P, Coupin G, Landry Y, Takeda K, Gies JP. Advanced glycation end products (AGEs) activate mast cells. Br J Pharmacol 2010; 161:442-55. [PMID: 20735427 PMCID: PMC2989594 DOI: 10.1111/j.1476-5381.2010.00905.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Accepted: 04/19/2010] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Advanced glycation endproducts (AGEs) represent one of the many types of chemical modifications that occur with age in long-lived proteins. AGEs also accumulate in pathologies such as diabetes, cardiovascular diseases, neurodegeneration and cancer. Mast cells are major effectors of acute inflammatory responses that also contribute to the progression of chronic diseases. Here we investigated interactions between AGEs and mast cells. EXPERIMENTAL APPROACHES Histamine secretion from AGEs-stimulated mast cells was measured. Involvement of a receptor for AGEs, RAGE, was assessed by PCR, immunostaining and use of inhibitors of RAGE. Production of reactive oxygen species (ROS) and cytokines was measured. KEY RESULTS Advanced glycation endproducts dose-dependently induced mast cell exocytosis with maximal effects being obtained within 20 s. RAGE mRNA was detected and intact cells were immunostained by a specific anti-RAGE monoclonal antibody. AGEs-induced exocytosis was inhibited by an anti-RAGE antibody and by low molecular weight heparin, a known RAGE antagonist. RAGE expression levels were unaltered after 3 h treatment with AGEs. AGE-RAGE signalling in mast cells involves Pertussis toxin-sensitive G(i)-proteins and intracellular Ca(2+) increases as pretreatment with Pertussis toxin, caffeine, 2-APB and BAPTA-AM inhibited AGE-induced exocytosis. AGEs also rapidly stimulated ROS production. After 6 h treatment with AGEs, the pattern of cytokine secretion was unaltered compared with controls. CONCLUSIONS AND IMPLICATIONS Advanced glycation endproducts activated mast cells and may contribute to a vicious cycle involving generation of ROS, increased formation of AGEs, activation of RAGE and to the increased low-grade inflammation typical of chronic diseases.
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Affiliation(s)
- E Sick
- Université de Strasbourg, Faculté de Pharmacie, Illkirch, France.
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137
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Lee YK, Choi IS, Ban JO, Lee HJ, Lee US, Han SB, Jung JK, Kim YH, Kim KH, Oh KW, Hong JT. 4-O-methylhonokiol attenuated β-amyloid-induced memory impairment through reduction of oxidative damages via inactivation of p38 MAP kinase. J Nutr Biochem 2010; 22:476-86. [PMID: 20688501 DOI: 10.1016/j.jnutbio.2010.04.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2009] [Revised: 04/04/2010] [Accepted: 04/05/2010] [Indexed: 11/16/2022]
Abstract
Oxidative stress induced neuronal cell death by accumulation of β-amyloid (Aβ) is a critical pathological mechanism of Alzheimer's disease (AD). Intracerebroventrical infusion of Aβ(1-42) (300 pmol/day per mouse) for 14 days induced neuronal cell death and memory impairment, but pre-treatment of 4-O-methylhonokiol (4-O-MH), a novel compound extracted from Magnolia officinalis for 3 weeks (0.2, 0.5 and 1.0 mg/kg) prior to the infusion of Aβ(1-42) and during the infusion dose dependently improved Aβ(1-42)-induced memory impairment and prevented neuronal cell death. Additionally, 4-O-MH reduced Aβ(1-42) infusion-induced oxidative damages of protein and lipid but reduced glutathione levels in the cortex and hippocampus. Aβ(1-42) infusion-induced activation of astrocytes and p38 mitogenic activated protein (MAP) kinase was also prevented by 4-O-MH in mice brains. In further study using culture cortical neurons, p38 MAP kinase inhibitor abolished the inhibitory effect of 4-O-MH (10 μM) on the Aβ(1-42) (5 μM)-induced reactive oxidative species generation and neuronal cell death. These results suggest that 4-O-MH might prevent the development and progression of AD through the reduction of oxidative stress and neuronal cell death via inactivation of p38 MAP kinase pathway.
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Affiliation(s)
- Yong Kyung Lee
- College of Pharmacy and MRC, Chungbuk National University, Heungduk-gu, Cheongju, Chungbuk 361-763, South Korea
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138
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Daborg J, von Otter M, Sjölander A, Nilsson S, Minthon L, Gustafson DR, Skoog I, Blennow K, Zetterberg H. Association of the RAGE G82S polymorphism with Alzheimer's disease. J Neural Transm (Vienna) 2010; 117:861-7. [PMID: 20567859 PMCID: PMC2895876 DOI: 10.1007/s00702-010-0437-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Accepted: 06/07/2010] [Indexed: 02/06/2023]
Abstract
The receptor for advanced glycation end-products (RAGE) has been implicated in several pathophysiological processes relevant to Alzheimer’s disease (AD), including transport and synaptotoxicity of AD-associated amyloid β (Aβ) peptides. A recent Chinese study (Li et al. in J Neural Transm 117:97–104, 2010) suggested an association between the 82S allele of the functional single nucleotide polymorphism (SNP) G82S (rs2070600) in the RAGE-encoding gene AGER and risk of AD. The present study aimed to investigate associations between AGER, AD diagnosis, cognitive scores and cerebrospinal fluid AD biomarkers in a European cohort of 316 neurochemically verified AD cases and 579 controls. Aside from G82S, three additional tag SNPs were analyzed to cover the common genetic variation in AGER. The 82S allele was associated with increased risk of AD (Pc = 0.04, OR = 2.0, 95% CI 1.2–3.4). There was no genetic interaction between AGER 82S and APOE ε4 in producing increased risk of AD (P = 0.4), and none of the AGER SNPs showed association with Aβ42, T-tau, P-tau181 or mini-mental state examination scores. The data speak for a weak, but significant effect of AGER on risk of AD.
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Affiliation(s)
- Jonny Daborg
- Department of Physiology, Institute of Neuroscience and Physiology, Sahlgrenska Academy at the University of Gothenburg, 432, 405 30, Gothenburg, Sweden.
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139
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Simard JC, Girard D, Tessier PA. Induction of neutrophil degranulation by S100A9 via a MAPK-dependent mechanism. J Leukoc Biol 2010; 87:905-14. [PMID: 20103766 DOI: 10.1189/jlb.1009676] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
S100A9 is a proinflammatory protein, expressed abundantly in the cytosol of neutrophils and monocytes. High extracellular S100A9 concentrations have been correlated with chronic inflammatory diseases such as rheumatoid arthritis and Crohn's disease, as well as with phagocyte extravasation. This study tested the hypothesis that S100A9 induces degranulation in human neutrophils. S100A9 was found to up-regulate the surface expression of CD35 and CD66b, proteins contained in secretory vesicles and specific/gelatinase granules, respectively. In addition, gelatinase and albumin, stored, respectively, in specific/gelatinase granules and secretory vesicles, were detected in the supernatants of neutrophils stimulated with S100A9. In contrast, stimulation with S100A9 had no effect on CD63 expression or MPO secretion, two proteins contained in azurophilic granules. S100A9 induced the phosphorylation of the MAPKs, ERK1/2, p38, and JNK. Inhibition of p38 and JNK but not ERK1/2, with specific inhibitors (SB203580, JNKII, and PD98059, respectively), blocked neutrophil degranulation induced by S100A9. Taken together, these results support the hypothesis and clearly indicate that S100A9 induces the degranulation of secretory and specific/gelatinase granules but not of azurophilic granules in a process involving p38 and JNK and further support its classification as a DAMP.
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Affiliation(s)
- Jean-Christophe Simard
- Laboratoire de Recherche en Inflammation et Physiologie des Granulocytes, Université du Québec, INRS-Institut Armand-Frappier, Laval, Quebec, Canada
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140
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Tsuruma K, Tanaka Y, Shimazawa M, Hara H. Induction of amyloid precursor protein by the neurotoxic peptide, amyloid-beta 25-35, causes retinal ganglion cell death. J Neurochem 2010; 113:1545-54. [PMID: 20374419 DOI: 10.1111/j.1471-4159.2010.06724.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Patients with Alzheimer's disease (AD) show a significantly increased incidence of glaucoma. AD is also associated with the occurrence of the neurotoxic peptide amyloid beta (Abeta). Therefore, we investigated whether Abeta is associated with retinal cell death in a retinal ganglion cell line (RGC-5). Treatment with Abeta(25-35), a neurotoxic fragment of Abeta, induced cell death in RGC-5 in both a concentration- and time-dependent manner. The amount of amyloid precursor protein was increased by treatment of RGC-5 and primary culture of mouse cortical neurons with fibril Abeta(25-35) and Abeta(1-42), which is a putative physiological neurotoxic fragment of Abeta present in AD. Amyloid precursor protein knockdown inhibited the cell death induced by Abeta(25-35). Treatment with Abeta(25-35) increased the amount of intracellular Abeta(1-40) and Abeta(1-42), while beta- and gamma-secretase inhibitors reduced cell death. Thus, the regulation of Abeta can be viewed as a new therapeutic target for glaucoma, especially in patients with coincident AD.
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Affiliation(s)
- Kazuhiro Tsuruma
- Department of Biofunctional Evaluation, Molecular Pharmacology, Gifu Pharmaceutical University, Gifu, Japan
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141
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Shi J, Guan J, Jiang B, Brenner DA, del Monte F, Ward JE, Connors LH, Sawyer DB, Semigran MJ, Macgillivray TE, Seldin DC, Falk R, Liao R. Amyloidogenic light chains induce cardiomyocyte contractile dysfunction and apoptosis via a non-canonical p38alpha MAPK pathway. Proc Natl Acad Sci U S A 2010; 107:4188-93. [PMID: 20150510 PMCID: PMC2840082 DOI: 10.1073/pnas.0912263107] [Citation(s) in RCA: 231] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Patients with primary (AL) cardiac amyloidosis suffer from progressive cardiomyopathy with a median survival of less than 8 months and a 5-year survival of <10%. Contributing to this poor prognosis is the fact that these patients generally do not tolerate standard heart failure therapies. The molecular mechanisms underlying this deadly form of heart disease remain unclear. Although interstitial amyloid fibril deposition of Ig light chain proteins is a major cause of cardiac dysfunction in AL cardiac amyloidosis, we have previously shown that amyloid precursor proteins directly impair cardiac function at the cellular and isolated organ levels, independent of fibril formation. In this study, we report that amyloidogenic light chain (AL-LC) proteins provoke oxidative stress, cellular dysfunction, and apoptosis in isolated adult cardiomyocytes through activation of p38 mitogen-activated protein kinase (MAPK). AL-LC-induced p38 activation was found to be independent of the upstream MAPK kinase, MKK3/6, and instead depends upon transforming growth factor-beta-activated protein kinase-1 binding protein-1 (TAB1)-mediated p38alpha MAPK autophosphorylation. Treatment of cardiomyocytes with SB203580, a selective p38 MAPK inhibitor, significantly attenuated AL-LC-induced oxidative stress, cellular dysfunction, and apoptosis. Our data provide a unique mechanistic insight into the pathogenesis of AL-LC cardiac toxicity and suggest that TAB1-mediated p38alpha MAPK autophosphorylation may serve as an important event leading to cardiac dysfunction and subsequent heart failure.
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Affiliation(s)
- Jianru Shi
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Jian Guan
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Molecular Medicine Graduate Program and
| | - Bingbing Jiang
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Daniel A. Brenner
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
| | - Federica del Monte
- Cardiovascular Institute, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215
| | - Jennifer E. Ward
- Amyloid Treatment and Research Program, Boston University School of Medicine, Boston, MA 02118
| | - Lawreen H. Connors
- Amyloid Treatment and Research Program, Boston University School of Medicine, Boston, MA 02118
| | - Douglas B. Sawyer
- Division of Cardiovascular Medicine, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN 37232
| | | | | | - David C. Seldin
- Molecular Medicine Graduate Program and
- Amyloid Treatment and Research Program, Boston University School of Medicine, Boston, MA 02118
| | - Rodney Falk
- Harvard Vanguard Medical Associates, Boston, MA 02116
| | - Ronglih Liao
- Cardiac Muscle Research Laboratory, Cardiovascular Division, Department of Medicine, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA 02115
- Molecular Medicine Graduate Program and
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142
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Abstract
Neurodegenerative diseases are characterized by progressive dysfunction of specific populations of neurons, determining clinical presentation. Neuronal loss is associated with extra and intracellular accumulation of misfolded proteins, the hallmarks of many neurodegenerative proteinopathies. Major basic processes include abnormal protein dynamics due to deficiency of the ubiquitin-proteosome-autophagy system, oxidative stress and free radical formation, mitochondrial dysfunction, impaired bioenergetics, dysfunction of neurotrophins, 'neuroinflammatory' processes and (secondary) disruptions of neuronal Golgi apparatus and axonal transport. These interrelated mechanisms lead to programmed cell death is a long run over many years. Neurodegenerative disorders are classified according to known genetic mechanisms or to major components of protein deposits, but recent studies showed both overlap and intraindividual diversities between different phenotypes. Synergistic mechanisms between pathological proteins suggest common pathogenic mechanisms. Animal models and other studies have provided insight into the basic neurodegeneration and cell death programs, offering new ways for future prevention/treatment strategies.
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Affiliation(s)
- Kurt A Jellinger
- Institute of Clinical Neurobiology, Kenyongasse, Vienna, Austria.
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143
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Origlia N, Arancio O, Domenici L, Yan SS. MAPK, beta-amyloid and synaptic dysfunction: the role of RAGE. Expert Rev Neurother 2010; 9:1635-45. [PMID: 19903023 DOI: 10.1586/ern.09.107] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Genetic and biological studies provide strong support for the hypothesis that accumulation of beta amyloid peptide (Abeta) contributes to the etiology of Alzheimer's disease (AD). Growing evidence indicates that oligomeric soluble Abeta plays an important role in the development of synaptic dysfunction and the impairment of cognitive function in AD. The receptor for advanced glycation end products (RAGE), a multiligand receptor in the immunoglobulin superfamily, acts as a cell surface binding site for Abeta and mediates alternations in the phosphorylation state of mitogen-activated protein kinase (MAPKs). Recent results have shown that MAPKs are involved in neurodegenerative processes. In particular, changes in the phosphorylation state of various MAPKs by Abeta lead to synaptic dysfunction and cognitive decline, as well as development of inflammatory responses in AD. The present review summarizes the evidence justifying a novel therapeutic approach focused on inhibition of RAGE signaling in order to arrest or halt the development of neuronal dysfunction in AD.
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144
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Ramasamy R, Yan SF, Schmidt AM. Polyol pathway and RAGE: a central metabolic and signaling axis in diabetic complications. Expert Rev Endocrinol Metab 2010; 5:65-75. [PMID: 30934384 DOI: 10.1586/eem.09.52] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
There are multiple metabolic and molecular consequences of hyperglycemia. This review will focus on the roles of the polyol pathway and the receptor for advanced glycation end products (RAGE) in the pathogenesis of diabetic complications. The lead enzyme of the polyol pathway, aldose reductase, transduces maladaptive effects of hyperglycemia by multiple mechanisms, at least in part via the generation of the products of nonenzymatic glycation of proteins, the advanced glycation end products (AGEs). Furthermore, seminal shifts in metabolic flux in the intracellular space stimulated by aldose reductase action activate signal transduction pathways, which alter gene expression and change cellular phenotype. Among the ligands of the multi-ligand receptor RAGE are the AGEs. AGE-RAGE stimulation mediates vascular and target cell dysfunction. The intersection and interdependence of the polyol pathway-RAGE connection suggest that targeting this axis may provide benefit in reducing the complications of diabetes.
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Affiliation(s)
- Ravichandran Ramasamy
- a Division of Surgical Science, Department of Surgery, Columbia University, College of Physicians and Surgeons, P&S 17-501, 630 West 168th Street, New York, NY 10032, USA
| | - Shi Fang Yan
- a Division of Surgical Science, Department of Surgery, Columbia University, College of Physicians and Surgeons, P&S 17-501, 630 West 168th Street, New York, NY 10032, USA
| | - Ann Marie Schmidt
- b Division of Surgical Science, Department of Surgery, Columbia University, College of Physicians and Surgeons, P&S 17-501, 630 West 168th Street, New York, NY 10032, USA.
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145
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Sakatani S, Yamada K, Homma C, Munesue S, Yamamoto Y, Yamamoto H, Hirase H. Deletion of RAGE causes hyperactivity and increased sensitivity to auditory stimuli in mice. PLoS One 2009; 4:e8309. [PMID: 20016851 PMCID: PMC2788702 DOI: 10.1371/journal.pone.0008309] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Accepted: 11/23/2009] [Indexed: 12/03/2022] Open
Abstract
The receptor for advanced glycation end-products (RAGE) is a multi-ligand receptor that belongs to the immunoglobulin superfamily of cell surface receptors. In diabetes and Alzheimer's disease, pathological progression is accelerated by activation of RAGE. However, how RAGE influences gross behavioral activity patterns in basal condition has not been addressed to date. In search for a functional role of RAGE in normal mice, a series of standard behavioral tests were performed on adult RAGE knockout (KO) mice. We observed a solid increase of home cage activity in RAGE KO. In addition, auditory startle response assessment resulted in a higher sensitivity to auditory signal and increased prepulse inhibition in KO mice. There were no significant differences between KO and wild types in behavioral tests for spatial memory and anxiety, as tested by Morris water maze, classical fear conditioning, and elevated plus maze. Our results raise a possibility that systemic therapeutic treatments to occlude RAGE activation may have adverse effects on general activity levels or sensitivity to auditory stimuli.
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Affiliation(s)
- Seiichi Sakatani
- Hirase Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Kazuyuki Yamada
- Research Resource Center, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Chihiro Homma
- Research Resource Center, RIKEN Brain Science Institute, Wako, Saitama, Japan
| | - Seiichi Munesue
- Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Yasuhiko Yamamoto
- Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Hiroshi Yamamoto
- Department of Biochemistry and Molecular Vascular Biology, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan
| | - Hajime Hirase
- Hirase Research Unit, RIKEN Brain Science Institute, Wako, Saitama, Japan
- Saitama University Brain Science Institute, Saitama, Japan
- * E-mail:
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146
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Munoz L, Ammit AJ. Targeting p38 MAPK pathway for the treatment of Alzheimer's disease. Neuropharmacology 2009; 58:561-8. [PMID: 19951717 DOI: 10.1016/j.neuropharm.2009.11.010] [Citation(s) in RCA: 265] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2009] [Revised: 10/30/2009] [Accepted: 11/24/2009] [Indexed: 10/20/2022]
Abstract
Accumulating evidence indicates that p38 mitogen-activated protein kinase (MAPK) could play more than one role in Alzheimer's disease (AD) pathophysiology and that patients suffering from AD dementia could benefit from p38 MAPK inhibitors. The p38 MAPK signalling has been widely accepted as a cascade contributing to neuroinflammation. However, deepening insight into the underlying biology of Alzheimer's disease reveals that p38 MAPK operates in other events related to AD, such as excitotoxicity, synaptic plasticity and tau phosphorylation. Although quantification of behavioural improvements upon p38 MAPK inhibition and in vivo evaluation of p38 MAPK significance to various aspects of AD pathology is still missing, the p38 MAPK is emerging as a new Alzheimer's disease treatment strategy. Thus, we present here an update on the role of p38 MAPK in neurodegeneration, with a focus on Alzheimer's disease, by summarizing recent literature and several key papers from earlier years.
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Affiliation(s)
- Lenka Munoz
- Department of Pharmaceutical Chemistry, Faculty of Pharmacy, The University of Sydney, NSW 2006, Australia.
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147
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Canas PM, Porciúncula LO, Cunha GMA, Silva CG, Machado NJ, Oliveira JMA, Oliveira CR, Cunha RA. Adenosine A2A receptor blockade prevents synaptotoxicity and memory dysfunction caused by beta-amyloid peptides via p38 mitogen-activated protein kinase pathway. J Neurosci 2009; 29:14741-51. [PMID: 19940169 PMCID: PMC6665997 DOI: 10.1523/jneurosci.3728-09.2009] [Citation(s) in RCA: 270] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2009] [Accepted: 09/30/2009] [Indexed: 12/14/2022] Open
Abstract
Alzheimer's disease (AD) is characterized by memory impairment, neurochemically by accumulation of beta-amyloid peptide (namely Abeta(1-42)) and morphologically by an initial loss of nerve terminals. Caffeine consumption prevents memory dysfunction in different models, which is mimicked by antagonists of adenosine A(2A) receptors (A(2A)Rs), which are located in synapses. Thus, we now tested whether A(2A)R blockade prevents the early Abeta(1-42)-induced synaptotoxicity and memory dysfunction and what are the underlying signaling pathways. The intracerebral administration of soluble Abeta(1-42) (2 nmol) in rats or mice caused, 2 weeks later, memory impairment (decreased performance in the Y-maze and object recognition tests) and a loss of nerve terminal markers (synaptophysin, SNAP-25) without overt neuronal loss, astrogliosis, or microgliosis. These were prevented by pharmacological blockade [5-amino-7-(2-phenylethyl)-2-(2-furyl)-pyrazolo[4,3-e]-1,2,4-triazolo[1,5-c]pyrimidine (SCH58261); 0.05 mg . kg(-1) . d(-1), i.p.; for 15 d] in rats, and genetic inactivation of A(2A)Rs in mice. Moreover, these were synaptic events since purified nerve terminals acutely exposed to Abeta(1-42) (500 nm) displayed mitochondrial dysfunction, which was prevented by A(2A)R blockade. SCH58261 (50 nm) also prevented the initial synaptotoxicity (loss of MAP-2, synaptophysin, and SNAP-25 immunoreactivity) and subsequent loss of viability of cultured hippocampal neurons exposed to Abeta(1-42) (500 nm). This A(2A)R-mediated control of neurotoxicity involved the control of Abeta(1-42)-induced p38 phosphorylation and was independent from cAMP/PKA (protein kinase A) pathway. Together, these results show that A(2A)Rs play a crucial role in the development of Abeta-induced synaptotoxicity leading to memory dysfunction through a p38 MAPK (mitogen-activated protein kinase)-dependent pathway and provide a molecular basis for the benefits of caffeine consumption in AD.
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Affiliation(s)
- Paula M. Canas
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Lisiane O. Porciúncula
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
- Department of Biochemistry, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, 90035-003, Porto Alegre, Brazil
| | - Geanne M. A. Cunha
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
- Department of Physiology and Pharmacology, Federal University of Ceará, 60430-270, Ceará, Brazil, and
| | - Carla G. Silva
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Nuno J. Machado
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Jorge M. A. Oliveira
- Rede de Química e Tecnologia, Serviço de Farmacologia, Faculdade de Farmácia, Universidade do Porto, 4050-047 Porto, Portugal
| | - Catarina R. Oliveira
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Rodrigo A. Cunha
- Center for Neuroscience of Coimbra, Institute of Biochemistry, Faculty of Medicine, University of Coimbra, 3004-504 Coimbra, Portugal
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148
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Fang F, Lue LF, Yan S, Xu H, Luddy JS, Chen D, Walker DG, Stern DM, Yan S, Schmidt AM, Chen JX, Yan SS. RAGE-dependent signaling in microglia contributes to neuroinflammation, Abeta accumulation, and impaired learning/memory in a mouse model of Alzheimer's disease. FASEB J 2009; 24:1043-55. [PMID: 19906677 DOI: 10.1096/fj.09-139634] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Microglia are critical for amyloid-beta peptide (Abeta)-mediated neuronal perturbation relevant to Alzheimer's disease (AD) pathogenesis. We demonstrate that overexpression of receptor for advanced glycation end products (RAGE) in imbroglio exaggerates neuroinflammation, as evidenced by increased proinflammatory mediator production, Abeta accumulation, impaired learning/memory, and neurotoxicity in an Abeta-rich environment. Transgenic (Tg) mice expressing human mutant APP (mAPP) in neurons and RAGE in microglia displayed enhanced IL-1beta and TNF-alpha production, increased infiltration of microglia and astrocytes, accumulation of Abeta, reduced acetylcholine esterase (AChE) activity, and accelerated deterioration of spatial learning/memory. Notably, introduction of a signal transduction-defective mutant RAGE (DN-RAGE) to microglia attenuates deterioration induced by Abeta. These findings indicate that RAGE signaling in microglia contributes to the pathogenesis of an inflammatory response that ultimately impairs neuronal function and directly affects amyloid accumulation. We conclude that blockade of microglial RAGE may have a beneficial effect on Abeta-mediated neuronal perturbation relevant to AD pathogenesis.-Fang, F., Lue, L.-F., Yan, S., Xu, H., Luddy, J. S., Chen, D., Walker, D. G., Stern, D. M., Yan, S., Schmidt, A. M., Chen, J. X., Yan, S. S. RAGE-dependent signaling in microglia contributes to neuroinflammation, Abeta accumulation, and impaired learning/memory in a mouse model of Alzheimer's disease.
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Affiliation(s)
- Fang Fang
- P&S 17-410, Department Surgery, College of Physicians and Surgeons, Columbia University, 630 West 168th St., New York, NY 10032, USA
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Association between the RAGE G82S polymorphism and Alzheimer’s disease. J Neural Transm (Vienna) 2009; 117:97-104. [DOI: 10.1007/s00702-009-0334-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2009] [Accepted: 10/19/2009] [Indexed: 10/20/2022]
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150
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RAGE-mediated signaling contributes to intraneuronal transport of amyloid-beta and neuronal dysfunction. Proc Natl Acad Sci U S A 2009; 106:20021-6. [PMID: 19901339 DOI: 10.1073/pnas.0905686106] [Citation(s) in RCA: 229] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Intracellular amyloid-beta peptide (Abeta) has been implicated in neuronal death associated with Alzheimer's disease. Although Abeta is predominantly secreted into the extracellular space, mechanisms of Abeta transport at the level of the neuronal cell membrane remain to be fully elucidated. We demonstrate that receptor for advanced glycation end products (RAGE) contributes to transport of Abeta from the cell surface to the intracellular space. Mouse cortical neurons exposed to extracellular human Abeta subsequently showed detectable peptide intracellularly in the cytosol and mitochondria by confocal microscope and immunogold electron microscopy. Pretreatment of cultured neurons from wild-type mice with neutralizing antibody to RAGE, and neurons from RAGE knockout mice displayed decreased uptake of Abeta and protection from Abeta-mediated mitochondrial dysfunction. Abeta activated p38 MAPK, but not SAPK/JNK, and then stimulated intracellular uptake of Abeta-RAGE complex. Similar intraneuronal co-localization of Abeta and RAGE was observed in the hippocampus of transgenic mice overexpressing mutant amyloid precursor protein. These findings indicate that RAGE contributes to mechanisms involved in the translocation of Abeta from the extracellular to the intracellular space, thereby enhancing Abeta cytotoxicity.
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