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Zhang M, Bouland GA, Holstege H, Reinders MJT. Identifying Aging and Alzheimer Disease-Associated Somatic Variations in Excitatory Neurons From the Human Frontal Cortex. Neurol Genet 2023; 9:e200066. [PMID: 37123987 PMCID: PMC10136684 DOI: 10.1212/nxg.0000000000200066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 02/03/2023] [Indexed: 05/02/2023]
Abstract
Background and Objectives With age, somatic mutations accumulated in human brain cells can lead to various neurologic disorders and brain tumors. Because the incidence rate of Alzheimer disease (AD) increases exponentially with age, investigating the association between AD and the accumulation of somatic mutation can help understand the etiology of AD. Methods We designed a somatic mutation detection workflow by contrasting genotypes derived from whole-genome sequencing (WGS) data with genotypes derived from scRNA-seq data and applied this workflow to 76 participants from the Religious Order Study and the Rush Memory and Aging Project (ROSMAP) cohort. We focused only on excitatory neurons, the dominant cell type in the scRNA-seq data. Results We identified 196 sites that harbored at least 1 individual with an excitatory neuron-specific somatic mutation (ENSM), and these 196 sites were mapped to 127 genes. The single base substitution (SBS) pattern of the putative ENSMs was best explained by signature SBS5 from the Catalogue of Somatic Mutations in Cancer (COSMIC) mutational signatures, a clock-like pattern correlating with the age of the individual. The count of ENSMs per individual also showed an increasing trend with age. Among the mutated sites, we found 2 sites tend to have more mutations in older individuals (16:6899517 [RBFOX1], p = 0.04; 4:21788463 [KCNIP4], p < 0.05). In addition, 2 sites were found to have a higher odds ratio to detect a somatic mutation in AD samples (6:73374221 [KCNQ5], p = 0.01 and 13:36667102 [DCLK1], p = 0.02). Thirty-two genes that harbor somatic mutations unique to AD and the KCNQ5 and DCLK1 genes were used for gene ontology (GO)-term enrichment analysis. We found the AD-specific ENSMs enriched in the GO-term "vocalization behavior" and "intraspecies interaction between organisms." Of interest we observed both age-specific and AD-specific ENSMs enriched in the K+ channel-associated genes. Discussion Our results show that combining scRNA-seq and WGS data can successfully detect putative somatic mutations. The putative somatic mutations detected from ROSMAP data set have provided new insights into the association of AD and aging with brain somatic mutagenesis.
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Affiliation(s)
- Meng Zhang
- Delft Bioinformatics Lab (M.Z., G.A.B., H.H., M.J.T.R.), Delft University of Technology; Department of Human Genetics (M.Z., H.H.), Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC; and Department of Human Genetics (G.A.B., M.J.T.R.), Leiden University Medical Center, the Netherlands
| | - Gerard A Bouland
- Delft Bioinformatics Lab (M.Z., G.A.B., H.H., M.J.T.R.), Delft University of Technology; Department of Human Genetics (M.Z., H.H.), Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC; and Department of Human Genetics (G.A.B., M.J.T.R.), Leiden University Medical Center, the Netherlands
| | - Henne Holstege
- Delft Bioinformatics Lab (M.Z., G.A.B., H.H., M.J.T.R.), Delft University of Technology; Department of Human Genetics (M.Z., H.H.), Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC; and Department of Human Genetics (G.A.B., M.J.T.R.), Leiden University Medical Center, the Netherlands
| | - Marcel J T Reinders
- Delft Bioinformatics Lab (M.Z., G.A.B., H.H., M.J.T.R.), Delft University of Technology; Department of Human Genetics (M.Z., H.H.), Amsterdam Neuroscience, Vrije Universiteit Amsterdam, Amsterdam UMC; and Department of Human Genetics (G.A.B., M.J.T.R.), Leiden University Medical Center, the Netherlands
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2
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CRISPR-activated patient fibroblasts for modeling of familial Alzheimer's disease. Neurosci Res 2021; 172:7-12. [PMID: 33819561 DOI: 10.1016/j.neures.2021.03.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Revised: 03/07/2021] [Accepted: 03/15/2021] [Indexed: 12/14/2022]
Abstract
Analyzing an appropriate disease model system is important to conduct disease research. Analyzing cells obtained from patient tissues could not only help elucidate the pathological mechanisms and to develop novel therapy but also lead to personalized medicine in the future. However, it is generally difficult to collect and culture neuronal cells from patients suffering from neurodegenerative disorders. Skin fibroblasts are easier to collect than neurons but may not show the expected pathology when disease-relevant genes are not sufficiently expressed. In this article, I describe an in vitro model system that enables the facile analysis of neurological disease mechanisms in patient fibroblast cultures by CRISPR transcriptional activation of endogenous disease-relevant genes. This system introduces an additional platform to analyze neurodegenerative disorders.
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Maqoud F, Scala R, Hoxha M, Zappacosta B, Tricarico D. ATP-sensitive potassium channel subunits in the neuroinflammation: novel drug targets in neurodegenerative disorders. CNS & NEUROLOGICAL DISORDERS-DRUG TARGETS 2021; 21:130-149. [PMID: 33463481 DOI: 10.2174/1871527320666210119095626] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 08/07/2020] [Accepted: 08/28/2020] [Indexed: 11/22/2022]
Abstract
Arachidonic acids and its metabolites modulate plenty of ligand-gated, voltage-dependent ion channels, and metabolically regulated potassium channels including ATP-sensitive potassium channels (KATP). KATP channels are hetero-multimeric complexes of sulfonylureas receptors (SUR1, SUR2A or SUR2B) and the pore-forming subunits (Kir6.1 and Kir6.2) likewise expressed in the pre-post synapsis of neurons and inflammatory cells, thereby affecting their proliferation and activity. KATP channels are involved in amyloid-β (Aβ)-induced pathology, therefore emerging as therapeutic targets against Alzheimer's and related diseases. The modulation of these channels can represent an innovative strategy for the treatment of neurodegenerative disorders; nevertheless, the currently available drugs are not selective for brain KATP channels and show contrasting effects. This phenomenon can be a consequence of the multiple physiological roles of the different varieties of KATP channels. Openings of cardiac and muscular KATP channel subunits, is protective against caspase-dependent atrophy in these tissues and some neurodegenerative disorders, whereas in some neuroinflammatory diseases benefits can be obtained through the inhibition of neuronal KATP channel subunits. For example, glibenclamide exerts an anti-inflammatory effect in respiratory, digestive, urological, and central nervous system (CNS) diseases, as well as in ischemia-reperfusion injury associated with abnormal SUR1-Trpm4/TNF-α or SUR1-Trpm4/ Nos2/ROS signaling. Despite this strategy is promising, glibenclamide may have limited clinical efficacy due to its unselective blocking action of SUR2A/B subunits also expressed in cardiovascular apparatus with pro-arrhythmic effects and SUR1 expressed in pancreatic beta cells with hypoglycemic risk. Alternatively, neuronal selective dual modulators showing agonist/antagonist actions on KATP channels can be an option.
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Affiliation(s)
- Fatima Maqoud
- Department of Pharmacy-Pharmaceutical Science, University of Bari Aldo Moro, via Orabona 4, 70125-I. Italy
| | - Rosa Scala
- Department of Pharmacy-Pharmaceutical Science, University of Bari Aldo Moro, via Orabona 4, 70125-I. Italy
| | - Malvina Hoxha
- Department of Chemical-Toxicological and Pharmacological Evaluation of Drugs, Faculty of Pharmacy, "Catholic University Our Lady of Good Counsel", Tirana. Albania
| | - Bruno Zappacosta
- Department of Chemical-Toxicological and Pharmacological Evaluation of Drugs, Faculty of Pharmacy, "Catholic University Our Lady of Good Counsel", Tirana. Albania
| | - Domenico Tricarico
- Department of Pharmacy-Pharmaceutical Science, University of Bari Aldo Moro, via Orabona 4, 70125-I. Italy
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Lourdes A. Vega Rasgado, Urbieta AT, Medina Jiménez JM. Influence of Mitochondrial ATP-Sensitive Potassium Channels on Toxic Effect of Amyloid-β 25–35. NEUROCHEM J+ 2020. [DOI: 10.1134/s181971242001016x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Villa C, Suphesiz H, Combi R, Akyuz E. Potassium channels in the neuronal homeostasis and neurodegenerative pathways underlying Alzheimer's disease: An update. Mech Ageing Dev 2019; 185:111197. [PMID: 31862274 DOI: 10.1016/j.mad.2019.111197] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/27/2019] [Accepted: 12/12/2019] [Indexed: 02/06/2023]
Abstract
With more than 80 subunits, potassium (K+) channels represent a group of ion channels showing high degree of diversity and ubiquity. They play important role in the control of membrane depolarization and cell excitability in several tissues, including the brain. Controlling the intracellular and extracellular K+ flow in cells, they also modulate the hormone and neurotransmitter release, apoptosis and cell proliferation. It is therefore not surprising that an improper functioning of K+ channels in neurons has been associated with pathophysiology of a wide range of neurological disorders, especially Alzheimer's disease (AD). This review aims to give a comprehensive overview of the basic properties and pathophysiological functions of the main classes of K+ channels in the context of disease processes, also discussing the progress, challenges and opportunities to develop drugs targeting these channels as potential pharmacological approach for AD treatment.
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Affiliation(s)
- Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, Italy
| | | | - Romina Combi
- School of Medicine and Surgery, University of Milano-Bicocca, Italy
| | - Enes Akyuz
- Yozgat Bozok University, Medical Faculty, Department of Biophysics, Yozgat, Turkey.
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Baheti K, Kale M. Methodologies Related to Computational Models in View of Developing Anti-Alzheimer Drugs: An Overview. Curr Drug Discov Technol 2018; 16:66-73. [PMID: 29663890 DOI: 10.2174/1570163815666180417120833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 04/06/2018] [Accepted: 04/13/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Since the last two decades, there has been more focus on the development strategies related to Anti-Alzheimer's drug research. This may be attributed to the fact that most of the Alzheimer's cases are still mostly unknown except for a few cases, where genetic differences have been identified. With the progress of the disease, the symptoms involve intellectual deterioration, memory impairment, abnormal personality and behavioural patterns, confusion, aggression, mood swings, irritability Current therapies available for this disease give only symptomatic relief and do not focus on manipulations of biololecular processes. METHODS Nearly all the therapies to treat Alzheimer's disease, target to change the amyloid cascade which is considered to be important in AD pathogenesis. New drug regimens are not able to keep pace with the ever-increasing understanding about dementia at the molecular level. Looking into these aggravated problems, we thought to put forth molecular modeling as a drug discovery approach for developing novel drugs to treat Alzheimer disease. The disease is incurable and it gets worst as it advances and finally causes death. Due to this, the design of drugs to treat this disease has become an utmost priority for research. One of the most important emerging technologies applied for this has been Computer-assisted drug design (CADD). It is a research tool that employs large-scale computing strategies in an attempt to develop a model receptor site which can be used for designing of an anti-Alzheimer drug. RESULTS Various models of amyloid-based calcium channels have been computationally optimized. Docking and De novo evolution are used to design the compounds. They are further subjected to absorption, distribution, metabolism, excretion and toxicity (ADMET) studies to finally bring about active compounds that are able to cross BBB. Many novel compounds have been designed which might be promising ones for the treatment of AD. CONCLUSION The present review describes the research carried out on various heterocyclic scaffolds that can serve as lead compounds to design Anti-Alzheimer's drugs in the future. The molecular modeling methods can thus become a better alternative for the discovery of newer Anti- Alzheimer agents. This methodology is extremely useful to design drugs in minimum time with enhanced activity keeping balanced ethical considerations. Thus, the researchers are opting for this improved process over the conventional methods hoping to achieve a sure shot way out for the sufferings of people affected by Alzheimer besides other diseases.
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Affiliation(s)
- Kirtee Baheti
- Department of Pharmaceutical Chemistry, Government College of Pharmacy, Aurangabad-431005, Maharashtra, India
| | - Mayura Kale
- Department of Pharmaceutical Chemistry, Government College of Pharmacy, Aurangabad-431005, Maharashtra, India
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Ge X, Sun Y, Ding F. Structures and dynamics of β-barrel oligomer intermediates of amyloid-beta16-22 aggregation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1687-1697. [PMID: 29550287 DOI: 10.1016/j.bbamem.2018.03.011] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2017] [Revised: 03/06/2018] [Accepted: 03/07/2018] [Indexed: 01/13/2023]
Abstract
Accumulating evidence suggests that soluble oligomers are more toxic than final fibrils of amyloid aggregations. Among the mixture of inter-converting intermediates with continuous distribution of sizes and secondary structures, oligomers in the β-barrel conformation - a common class of protein folds with a closed β-sheet - have been postulated as the toxic species with well-defined three-dimensional structures to perform pathological functions. A common mechanism for amyloid toxicity, therefore, implies that all amyloid peptides should be able to form β-barrel oligomers as the aggregation intermediates. Here, we applied all-atom discrete molecular dynamics (DMD) simulations to evaluate the formation of β-barrel oligomers and characterize their structures and dynamics in the aggregation of a seven-residue amyloid peptide, corresponding to the amyloid core of amyloid-β with a sequence of 16KLVFFAE22 (Aβ16-22). We carried out aggregation simulations with various numbers of peptides to study the size dependence of aggregation dynamics and assembly structures. Consistent with previous computational studies, we observed the formation of β-barrel oligomers in all-atom DMD simulations. Using a network-based approach to automatically identify β-barrel conformations, we systematically characterized β-barrels of various sizes. Our simulations revealed the conformational inter-conversion between β-barrels and double-layer β-sheets due to increased structural strains upon forming a closed β-barrel while maximizing backbone hydrogen bonds. The potential of mean force analysis further characterized the free energy barriers between these two states. The obtained structural and dynamic insights of β-barrel oligomers may help better understand the molecular mechanism of oligomer toxicities and design novel therapeutics targeting the toxic β-barrel oligomers. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Xinwei Ge
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Yunxiang Sun
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States.
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8
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Joshi AU, Saw NL, Shamloo M, Mochly-Rosen D. Drp1/Fis1 interaction mediates mitochondrial dysfunction, bioenergetic failure and cognitive decline in Alzheimer's disease. Oncotarget 2017; 9:6128-6143. [PMID: 29464060 PMCID: PMC5814200 DOI: 10.18632/oncotarget.23640] [Citation(s) in RCA: 87] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2017] [Accepted: 11/26/2017] [Indexed: 11/25/2022] Open
Abstract
Mitochondrial dynamics, involving a balance between fusion and fission, regulates mitochondrial quality and number. Increasing evidence suggests that dysfunctional mitochondria play a role in Alzheimer's disease (AD). We observed that Drp1 interaction with one of the adaptors, Fis1, is significantly increased in Aβ-treated neurons and AD patient-derived fibroblasts. P110, a seven-amino acid peptide, which specifically inhibits Drp1/Fis1 interaction without affecting the interaction of Drp1 with its other adaptors, attenuated Aβ42-induced mitochondrial recruitment of Drp1 and prevented mitochondrial structural and functional dysfunction in cultured neurons, in cells expressing mutant amyloid precursor protein (KM670/671NL), and in five different AD patient-derived fibroblasts. Importantly, sustained P110 treatment significantly improved behavioral deficits, and reduced Aβ accumulation, energetic failure and oxidative stress in the brain of the AD mouse model, 5XFAD. This suggests that Drp1/Fis1 interaction and excessive mitochondrial fission greatly contribute to Aβ-mediated and AD-related neuropathology and cognitive decline. Therefore, inhibiting excessive Drp1/Fis1-mediated mitochondrial fission may benefit AD patients.
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Affiliation(s)
- Amit U Joshi
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nay L Saw
- Behavioral and Functional Neuroscience Laboratory, Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Mehrdad Shamloo
- Behavioral and Functional Neuroscience Laboratory, Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Daria Mochly-Rosen
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, CA 94305, USA
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9
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Koselski M, Olszewska A, Hordyjewska A, Malecka-Massalska T, Trebacz K. Three types of ion channels in the cell membrane of mouse fibroblasts. Physiol Res 2017; 66:63-73. [PMID: 27782747 DOI: 10.33549/physiolres.933358] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Patch clamp recordings carried out in the inside-out configuration revealed activity of three kinds of channels: nonselective cation channels, small-conductance K(+) channels, and large-conductance anion channels. The nonselective cation channels did not distinguish between Na(+) and K(+). The unitary conductance of these channels reached 28 pS in a symmetrical concentration of 200 mM NaCl. A lower value of this parameter was recorded for the small-conductance K(+) channels and in a 50-fold gradient of K(+) (200 mM/4 mM) it reached 8 pS. The high selectivity of these channels to potassium was confirmed by the reversal potential (-97 mV), whose value was close to the equilibrium potential for potassium (-100 mV). One of the features of the largeconductance anion channels was high conductance amounting to 493 pS in a symmetrical concentration of 200 mM NaCl. The channels exhibited three subconductance levels. Moreover, an increase in the open probability of the channels at voltages close to zero was observed. The anion selectivity of the channels was low, because the channels were permeable to both Cl(-) and gluconate - a large anion. Research on the calcium dependence revealed that internal calcium activates nonselective cation channels and small-conductance K(+) channels, but not largeconductance anion channels.
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Affiliation(s)
- M Koselski
- Department of Biophysics, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University, Lublin, Poland.
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Brain mitochondrial ATP-insensitive large conductance Ca⁺²-activated K⁺ channel properties are altered in a rat model of amyloid-β neurotoxicity. Exp Neurol 2015; 269:8-16. [PMID: 25828534 DOI: 10.1016/j.expneurol.2014.12.024] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2014] [Revised: 12/01/2014] [Accepted: 12/20/2014] [Indexed: 12/22/2022]
Abstract
Mitochondrial dysfunction is a hallmark of amyloid-beta (Aβ)-induced neuronal toxicity in Alzheimer's disease (AD). However, the underlying mechanism of how Aβ affects mitochondrial function remains uncertain. Because mitochondrial potassium channels have been involved in several mitochondrial functions including cytoprotection, apoptosis and calcium homeostasis, a study was undertaken to investigate whether the gating behavior of the mitochondrial ATP- and ChTx-insensitive-IbTx-sensitive Ca(2+)-activated potassium channel (mitoBKCa) is altered in a rat model of Aβ neurotoxicity. Aβ1-42 (4 μg/μl) was intracerebroventricularly injected in male Wistar rats (220-250 g). Brain Aβ accumulation was confirmed two weeks later on the basis of an immunohistochemistry staining assay, and physiological impacts measured in passive avoidance task cognitive performance experiments. Brain mitochondrial inner membranes were then extracted and membrane vesicles prepared for channel incorporation into bilayer lipid. Purity of the cell fraction was confirmed by Western blot using specific markers of mitochondria, plasma membrane, endoplasmic reticulum, and Golgi. Our results first provide evidence for differences in mitoBKCa ion permeation properties with channels coming from Aβ vesicle preparations characterized by an inward rectifying I-V curve, in contrast to control mitoBKCa channels which showed a linear I-V relationship under the same ionic conditions (200 mM cis/50mM trans). More importantly the open probability of channels from Aβ vesicles appeared 1.5 to 2.5 smaller compared to controls, the most significant decrease being observed at depolarizing potentials (30 mV to 50 mV). Because BKCa-β4 subunit has been documented to shift the BKCa channel voltage dependence curve, a Western blot analysis was undertaken where expression of mitoBKCa α and β4 subunits was estimated using anti-α and β4 subunit antibodies. Our results indicated a significant increase in mitoBKCa-β4 subunit expression coupled to a decrease in the expression of α subunit. Our results thus demonstrate a modification in the mitoBKCa channel gating properties in membrane preparations coming from a rat model of Aβ neurotoxicity, an effect potentially linked to a change in mitoBKCa-β4 and -α subunits expression or increased ROS production due to an enhanced Aβ mitochondrial accumulation. Our results may provide new insights into the cellular mechanisms underlying mitochondrial dysfunctions in Aβ neurotoxicity.
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Anemaet IG, van Heusden GPH. Transcriptional response of Saccharomyces cerevisiae to potassium starvation. BMC Genomics 2014; 15:1040. [PMID: 25432801 PMCID: PMC4289377 DOI: 10.1186/1471-2164-15-1040] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 11/24/2014] [Indexed: 01/28/2023] Open
Abstract
Background Ion homeostasis is essential for every cell and aberrant cation homeostasis is related to diseases like Alzheimer’s disease and epilepsy. The mechanisms responsible for cation homeostasis are only partly understood. The yeast Saccharomyces cerevisiae is an excellent organism to study fundamental aspects of cation homeostasis. In this study we investigated the transcriptional response of this yeast to potassium starvation by using Serial Analysis of Gene Expression (SAGE)-tag sequencing. Results Comparison of transcript levels in cells grown for 60 min in media without potassium with those in cells grown under standard potassium concentrations showed that the mRNA levels of 105 genes were significantly (P < 0.01) up-regulated more than 2.0-fold during potassium starvation and the mRNA levels of 172 genes significantly down-regulated. These genes belong to several functional categories. Genes involved in stress response including HSP30, YRO2 and TPO2 and phosphate metabolism including PHO84, PHO5 and SPL2 were highly up-regulated. Analysis of the promoter of PHO84 encoding a high affinity phosphate transporter, revealed that increased PHO84 RNA levels are caused by both increased Pho4-dependent transcription and decreased RNA turnover. In the latter process antisense transcription may be involved. Many genes involved in cell cycle control, and to a lesser extent genes involved in amino acid transport, were strongly down-regulated. Conclusions Our study showed that yeast cells respond to potassium starvation in a complex way and reveals a direct link between potassium homeostasis and phosphate metabolism. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1040) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - G Paul H van Heusden
- Institute of Biology, Leiden University, Sylviusweg 72, Leiden 2333BE, The Netherlands.
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Chen T, Gai WP, Abbott CA. Dipeptidyl peptidase 10 (DPP10(789)): a voltage gated potassium channel associated protein is abnormally expressed in Alzheimer's and other neurodegenerative diseases. BIOMED RESEARCH INTERNATIONAL 2014; 2014:209398. [PMID: 25025038 PMCID: PMC4084682 DOI: 10.1155/2014/209398] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2014] [Accepted: 04/23/2014] [Indexed: 12/15/2022]
Abstract
The neuropathological features associated with Alzheimer's disease (AD) include the presence of extracellular amyloid-β peptide-containing plaques and intracellular tau positive neurofibrillary tangles and the loss of synapses and neurons in defined regions of the brain. Dipeptidyl peptidase 10 (DPP10) is a protein that facilitates Kv4 channel surface expression and neuronal excitability. This study aims to explore DPP10789 protein distribution in human brains and its contribution to the neurofibrillary pathology of AD and other tauopathies. Immunohistochemical analysis revealed predominant neuronal staining of DPP10789 in control brains, and the CA1 region of the hippocampus contained strong reactivity in the distal dendrites of the pyramidal cells. In AD brains, robust DPP10789 reactivity was detected in neurofibrillary tangles and plaque-associated dystrophic neurites, most of which colocalized with the doubly phosphorylated Ser-202/Thr-205 tau epitope. DPP10789 positive neurofibrillary tangles and plaque-associated dystrophic neurites also appeared in other neurodegenerative diseases such as frontotemporal lobar degeneration, diffuse Lewy body disease, and progressive supranuclear palsy. Occasional DPP10789 positive neurofibrillary tangles and neurites were seen in some aged control brains. Western blot analysis showed both full length and truncated DPP10789 fragments with the later increasing significantly in AD brains compared to control brains. Our results suggest that DPP10789 is involved in the pathology of AD and other neurodegenerative diseases.
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Affiliation(s)
- Tong Chen
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Wei-Ping Gai
- Department of Human Physiology, School of Medicine, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
| | - Catherine A. Abbott
- School of Biological Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia
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Mocali A, Della Malva N, Abete C, Mitidieri Costanza VA, Bavazzano A, Boddi V, Sanchez L, Dessì S, Pani A, Paoletti F. Altered proteolysis in fibroblasts of Alzheimer patients with predictive implications for subjects at risk of disease. Int J Alzheimers Dis 2014; 2014:520152. [PMID: 24949214 PMCID: PMC4052202 DOI: 10.1155/2014/520152] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2014] [Revised: 04/09/2014] [Accepted: 05/04/2014] [Indexed: 02/04/2023] Open
Abstract
There is great interest in developing reliable biomarkers to support antemortem diagnosis of late-onset Alzheimer's disease (AD). Early prediction and diagnosis of AD might be improved by the detection of a proteolytic dysfunction in extracts from cultured AD fibroblasts, producing altered isoelectrophoretic forms of the enzyme transketolase (TK-alkaline bands). The TK profile and apolipoprotein E (APOE) genotype were examined in fibroblasts from 36 clinically diagnosed probable late-onset sporadic AD patients and 38 of their asymptomatic relatives, 29 elderly healthy individuals, 12 neurological non-AD patients, and 5 early-onset AD patients. TK alterations occurred in (i) several probable AD patients regardless of age-of-onset and severity of disease; (ii) all early-onset AD patients and APOE ε 4/4 carriers; and (iii) nearly half of asymptomatic AD relatives. Normal subjects and non-AD patients were all negative. Notably, culture conditions promoting TK alterations were also effective in increasing active BACE1 levels. Overall, the TK assay might represent a low-cost laboratory tool useful for supporting AD differential diagnosis and identifying asymptomatic subjects who are at greater risk of AD and who should enter a follow-up study. Moreover, the cultured fibroblasts were confirmed as a useful in vitro model for further studies on the pathogenetic process of AD.
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Affiliation(s)
- Alessandra Mocali
- Section of Experimental Pathology and Oncology, Department of Biomedical Experimental and Clinical Sciences, University of Florence, 50134 Florence, Italy
| | - Nunzia Della Malva
- Section of Experimental Pathology and Oncology, Department of Biomedical Experimental and Clinical Sciences, University of Florence, 50134 Florence, Italy
| | - Claudia Abete
- Department of Internal Medicine, University of Cagliari, 09042 Monserrato, Italy
| | | | | | - Vieri Boddi
- Department of Public Health, University of Florence, 50134 Florence, Italy
| | - Luis Sanchez
- 1st Unit of General Surgery and Transplantation, Careggi Hospital, 50134 Florence, Italy
| | - Sandra Dessì
- Department of Internal Medicine, University of Cagliari, 09042 Monserrato, Italy
| | - Alessandra Pani
- Department of Biomedical Sciences, University of Cagliari, 09042 Monserrato, Italy
| | - Francesco Paoletti
- Section of Experimental Pathology and Oncology, Department of Biomedical Experimental and Clinical Sciences, University of Florence, 50134 Florence, Italy
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Wu CT, Qi XY, Huang H, Naud P, Dawson K, Yeh YH, Harada M, Kuo CT, Nattel S. Disease and region-related cardiac fibroblast potassium current variations and potential functional significance. Cardiovasc Res 2014; 102:487-96. [PMID: 24596399 DOI: 10.1093/cvr/cvu055] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
AIMS Fibroblasts, which play an important role in cardiac function/dysfunction, including arrhythmogenesis, have voltage-dependent (Kv) currents of unknown importance. Here, we assessed the differential expression of Kv currents between atrial and ventricular fibroblasts from control dogs and dogs with an atrial arrhythmogenic substrate caused by congestive heart failure (CHF). METHODS AND RESULTS Left atrial (LA) and ventricular (LV) fibroblasts were freshly isolated from control and CHF dogs (2-week ventricular tachypacing, 240 bpm). Kv currents were measured with whole-cell voltage-clamp, mRNA by quantitative polymerase chain reaction (qPCR) and fibroblast proliferation by (3)H-thymidine incorporation. Robust voltage-dependent tetraethylammonium (TEA)-sensitive K(+) currents (IC50 ∼1 mM) were recorded. The morphologies and TEA responses of LA and LV fibroblast Kv currents were similar. LV fibroblast Kv-current densities were significantly greater than LA, and Kv-current densities were significantly less in CHF than control. The mRNA expression of Kv-channel subunits Kv1.5 and Kv4.3 was less in LA vs. LV fibroblasts and was down-regulated in CHF, consistent with K(+)-current recordings. Ca(2+)-dependent K(+)-channel subunit (KCa1.1) mRNA and currents were less expressed in LV vs. LA fibroblasts. Inhibiting LA fibroblast K(+) current with 1 mmol/L of TEA or KCa1.1 current with paxilline increased proliferation. CONCLUSIONS Fibroblast Kv-current expression is smaller in CHF vs. control, as well as LA vs. LV. KCa1.1 current is greater in LA vs. LV. Suppressing Kv current with TEA enhances fibroblast proliferation, suggesting that Kv current might act to check fibroblast proliferation and that reduced Kv current in CHF may contribute to fibrosis. Fibroblast Kv-current remodelling may play a role in the atrial fibrillation (AF) substrate; modulating fibroblast K(+) channels may present a novel strategy to prevent fibrosis and AF.
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Affiliation(s)
- Chia-Tung Wu
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Xiao-Yan Qi
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Hai Huang
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Patrice Naud
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8
| | - Kristin Dawson
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
| | - Yung-Hsin Yeh
- Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Masahide Harada
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Cardiology, Hamamatsu Medical Center, Hamamatsu, Japan
| | - Chi-Tai Kuo
- Chang-Gung Memorial Hospital and University, Taoyuan, Taiwan, Republic of China
| | - Stanley Nattel
- Research Center, Montreal Heart Institute, Université de Montréal, 5000 Belanger St. E., Montreal, QC, Canada H1T 1C8 Department of Pharmacology and Therapeutics, McGill University, Montreal, QC, Canada
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15
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Tian C, Zhu R, Zhu L, Qiu T, Cao Z, Kang T. Potassium Channels: Structures, Diseases, and Modulators. Chem Biol Drug Des 2013; 83:1-26. [DOI: 10.1111/cbdd.12237] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Chuan Tian
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
- School of Pharmacy; Liaoning University of Traditional Chinese Medicine; Dalian Liaoning 116600 China
| | - Ruixin Zhu
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Lixin Zhu
- Department of Pediatrics; Digestive Diseases and Nutrition Center; The State University of New York at Buffalo; Buffalo NY 14226 USA
| | - Tianyi Qiu
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Zhiwei Cao
- School of Life Sciences and Technology; Tongji University; Shanghai 200092 China
| | - Tingguo Kang
- School of Pharmacy; Liaoning University of Traditional Chinese Medicine; Dalian Liaoning 116600 China
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16
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Campolongo P, Ratano P, Ciotti MT, Florenzano F, Nori SL, Marolda R, Palmery M, Rinaldi AM, Zona C, Possenti R, Calissano P, Severini C. Systemic administration of substance P recovers beta amyloid-induced cognitive deficits in rat: involvement of Kv potassium channels. PLoS One 2013; 8:e78036. [PMID: 24265678 PMCID: PMC3827079 DOI: 10.1371/journal.pone.0078036] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Accepted: 09/16/2013] [Indexed: 11/18/2022] Open
Abstract
Reduced levels of Substance P (SP), an endogenous neuropeptide endowed with neuroprotective and anti-apoptotic properties, have been found in brain and spinal fluid of Alzheimer's disease (AD) patients. Potassium (K(+)) channel dysfunction is implicated in AD development and the amyloid-β (Aβ)-induced up-regulation of voltage-gated potassium channel subunits could be considered a significant step in Aβ brain toxicity. The aim of this study was to evaluate whether SP could reduce, in vivo, Aβ-induced overexpression of Kv subunits. Rats were intracerebroventricularly infused with amyloid-β 25-35 (Aβ25-35, 20 µg) peptide. SP (50 µg/Kg, i.p.) was daily administered, for 7 days starting from the day of the surgery. Here we demonstrate that the Aβ infused rats showed impairment in cognitive performances in the Morris water maze task 4 weeks after Aβ25-35 infusion and that this impairing effect was prevented by SP administration. Kv1.4, Kv2.1 and Kv4.2 subunit levels were quantified in hippocampus and in cerebral cortex by Western blot analysis and immunofluorescence. Interestingly, SP reduced Kv1.4 levels overexpressed by Aβ, both in hippocampus and cerebral cortex. Our findings provide in vivo evidence for a neuroprotective activity of systemic administration of SP in a rat model of AD and suggest a possible mechanism underlying this effect.
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Affiliation(s)
- Patrizia Campolongo
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Patrizia Ratano
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | | | - Fulvio Florenzano
- Institute of Cell Biology and Neurobiology, CNR, Rome, Italy
- European Brain Research Institute, Rome, Italy
| | - Stefania Lucia Nori
- Department of Medicine and Surgery, University of Salerno Medicine Campus, Baronissi (SA), Italy
| | - Roberta Marolda
- Institute of Cell Biology and Neurobiology, CNR, Rome, Italy
| | - Maura Palmery
- Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy
| | - Anna Maria Rinaldi
- Department of Neuroscience, University of Rome “Tor Vergata”, Rome, Italy
| | - Cristina Zona
- Department of Neuroscience, University of Rome “Tor Vergata”, Rome, Italy
- IRCCS Fondazione Santa Lucia, Rome, Italy
| | - Roberta Possenti
- Department of Neuroscience, University of Rome “Tor Vergata”, Rome, Italy
| | | | - Cinzia Severini
- Institute of Cell Biology and Neurobiology, CNR, Rome, Italy
- * E-mail:
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17
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Noguchi T, Wang CW, Pan H, Welsh DK. Fibroblast circadian rhythms of PER2 expression depend on membrane potential and intracellular calcium. Chronobiol Int 2012; 29:653-64. [PMID: 22734566 DOI: 10.3109/07420528.2012.679330] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The suprachiasmatic nucleus (SCN) of the hypothalamus synchronizes circadian rhythms of cells and tissues throughout the body. In SCN neurons, rhythms of clock gene expression are suppressed by manipulations that hyperpolarize the plasma membrane or lower intracellular Ca(2+). However, whether clocks in other cells also depend on membrane potential and calcium is unknown. In this study, the authors investigate the effects of membrane potential and intracellular calcium on circadian rhythms in mouse primary fibroblasts. Rhythms of clock gene expression were monitored using a PER2::LUC knockin reporter. Rhythms were lost or delayed at lower (hyperpolarizing) K(+) concentrations. Bioluminescence imaging revealed that this loss of rhythmicity in cultures was due to loss of rhythmicity of single cells rather than loss of synchrony among cells. In lower Ca(2+) concentrations, rhythms were advanced or had shorter periods. Buffering intracellular Ca(2+) by the calcium chelator 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid tetrakis acetoxymethyl ester (BAPTA-AM) or manipulation of inositol triphosphate (IP(3))-sensitive intracellular calcium stores by thapsigargin delayed rhythms. These results suggest that the circadian clock in fibroblasts, as in SCN neurons, is regulated by membrane potential and Ca(2+). Changes in intracellular Ca(2+) may mediate the effects of membrane potential observed in this study.
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Affiliation(s)
- Takako Noguchi
- Department of Psychiatry and Center for Chronobiology, University of California, San Diego, La Jolla, USA
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18
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Massone S, Vassallo I, Castelnuovo M, Fiorino G, Gatta E, Robello M, Borghi R, Tabaton M, Russo C, Dieci G, Cancedda R, Pagano A. RNA polymerase III drives alternative splicing of the potassium channel-interacting protein contributing to brain complexity and neurodegeneration. ACTA ACUST UNITED AC 2011; 193:851-66. [PMID: 21624954 PMCID: PMC3105541 DOI: 10.1083/jcb.201011053] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
An RNA polymerase III–transcribed noncoding RNA promotes alternative splicing of KCNIP4, altering amyloid precursor protein processing and contributing to neurodegeneration. Alternative splicing generates protein isoforms that are conditionally or differentially expressed in specific tissues. The discovery of factors that control alternative splicing might clarify the molecular basis of biological and pathological processes. We found that IL1-α−dependent up-regulation of 38A, a small ribonucleic acid (RNA) polymerase III–transcribed RNA, drives the synthesis of an alternatively spliced form of the potassium channel–interacting protein (KCNIP4). The alternative KCNIP4 isoform cannot interact with the γ-secretase complex, resulting in modification of γ-secretase activity, amyloid precursor protein processing, and increased secretion of β-amyloid enriched in the more toxic Aβ x-42 species. Notably, synthesis of the variant KCNIP4 isoform is also detrimental to brain physiology, as it results in the concomitant blockade of the fast kinetics of potassium channels. This alternative splicing shift is observed at high frequency in tissue samples from Alzheimer’s disease patients, suggesting that RNA polymerase III cogenes may be upstream determinants of alternative splicing that significantly contribute to homeostasis and pathogenesis in the brain.
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Affiliation(s)
- Sara Massone
- Department of Oncology, Biology, and Genetics, National Institute for Cancer Research, 16132 Genoa, Italy
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19
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Zironi I, Gaibani P, Remondini D, Salvioli S, Altilia S, Pierini M, Aicardi G, Verondini E, Milanesi L, Bersani F, Gravina S, Roninson IB, Franceschi C, Castellani G. Molecular remodeling of potassium channels in fibroblasts from centenarians: A marker of longevity? Mech Ageing Dev 2010; 131:674-81. [DOI: 10.1016/j.mad.2010.09.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2010] [Revised: 08/09/2010] [Accepted: 09/10/2010] [Indexed: 01/06/2023]
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20
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Vicente MI, Costa PF, Lima PA. Galantamine inhibits slowly inactivating K+ currents with a dual dose–response relationship in differentiated N1E-115 cells and in CA1 neurones. Eur J Pharmacol 2010; 634:16-25. [DOI: 10.1016/j.ejphar.2010.02.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2009] [Revised: 01/26/2010] [Accepted: 02/13/2010] [Indexed: 11/15/2022]
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21
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Poulopoulou C, Markakis I, Davaki P, Tsaltas E, Rombos A, Hatzimanolis A, Vassilopoulos D. Aberrant modulation of a delayed rectifier potassium channel by glutamate in Alzheimer's disease. Neurobiol Dis 2010; 37:339-48. [DOI: 10.1016/j.nbd.2009.10.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2009] [Revised: 09/08/2009] [Accepted: 10/10/2009] [Indexed: 12/21/2022] Open
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22
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Oxidation of potassium channels by ROS: a general mechanism of aging and neurodegeneration? Trends Cell Biol 2010; 20:45-51. [DOI: 10.1016/j.tcb.2009.09.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 09/23/2009] [Accepted: 09/24/2009] [Indexed: 12/13/2022]
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23
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Khan TK, Nelson TJ, Verma VA, Wender PA, Alkon DL. A cellular model of Alzheimer's disease therapeutic efficacy: PKC activation reverses Abeta-induced biomarker abnormality on cultured fibroblasts. Neurobiol Dis 2009; 34:332-9. [PMID: 19233276 DOI: 10.1016/j.nbd.2009.02.003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2008] [Accepted: 02/03/2009] [Indexed: 12/21/2022] Open
Abstract
PKC signaling is critical for the non-toxic degradation of amyloid precursor protein (APP) and inhibition of GSK3beta, which controls phosphorylation of tau protein in Alzheimer's disease (AD). Thus the misregulation of PKC signaling could contribute to the origins of AD. Bryostatin, a potent PKC modulator, has the potential to ameliorate both the neurodegeneration and the recent memory loss associated with AD. As reported herein bryostatin and a potent synthetic analog (picolog) are found to cause stimulation of non-amyloidogenic pathways by increasing alpha-secretase activity and thus lowering the amount of toxic Abeta produced. Both bryostatin and picolog increased the secretion of the alpha-secretase product (s-APP-alpha) of APP at sub-nanomolar to nanomolar concentrations. A peripheral AD-Biomarker has previously been autopsy-validated. This Biomarker, based on bradykinin-induced differential phosphorylation of Erk1 and Erk2, has been used here to test the therapeutic efficacy both for bryostatin and picolog. Both of these PKC activators are then shown to convert the AD Erk1/2 phenotype of fibroblasts into the phenotype of "normal" control skin fibroblasts. This conversion occurred for both the abnormal Erk1/2 phenotype induced by application of Abeta(1-42) to the fibroblasts or the phenotype observed for fibroblasts of AD patients. The Abeta(1-42)-induction, and PKC modulator reversal of the AD Erk1/2 biomarker phenotype demonstrate the AD-Biomarker's potential to monitor both disease progression and treatment response. Additionally, this first demonstration of the therapeutic potential in AD of a synthetically accessible bryostatin analog warrants further preclinical advancement.
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Affiliation(s)
- Tapan K Khan
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, 26506, USA.
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24
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Khan TK, Alkon DL. Early diagnostic accuracy and pathophysiologic relevance of an autopsy-confirmed Alzheimer's disease peripheral biomarker. Neurobiol Aging 2008; 31:889-900. [PMID: 18760507 DOI: 10.1016/j.neurobiolaging.2008.07.010] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2007] [Revised: 07/10/2008] [Accepted: 07/11/2008] [Indexed: 11/28/2022]
Abstract
Treatment of Alzheimer's disease (AD) and the discovery of promising drug candidates depend on early diagnosis. Few currently available diagnostic tests have significantly improved this early uncertainty, while the "gold standard" diagnosis continues to require clinical dementia in life and the presence of pathologic brain lesions of amyloid plaques and neurofibrillary tangles in the brain at autopsy. Here, the inflammatory agonist bradykinin, a small nano-peptide, that induces PKC-mediated phosphorylation of Erk1 and Erk2 in fibroblasts, was applied to punch-biopsy-obtained human skin fibroblasts. Quantitative imaging of the phosphorylated Erk1 and Erk2 bands was then used in a ratio that is mathematically configured into an AD-Biomarker Index (AD-Index). In the population described here (N=264), there were 64 autopsy examinations. Demented individuals were clinically diagnosed as AD with an overall accuracy of 78%. Among the 42 autopsy-confirmed cases for which there were also AD-Biomarker measurements, the overall accuracy of the AD-Biomarker was 98%. Among both the autopsy-confirmed and the clinically diagnosed patients, the AD-Index values were inversely correlated with the duration of disease, i.e., the time from the onset of dementia symptoms. Among the autopsy-confirmed cases, the AD-Biomarker diagnosis showed remarkably high sensitivity (97%) and specificity (100%) compared to clinical diagnosis (sensitivity: 78% and specificity: 20%). Using autopsy validation, the clinical diagnosis was only accurate at 52% level vs. the AD-Biomarker accuracy of 100% for cases with dementia not larger than 4 years of duration. Finally, application of soluble Abeta(1-42) to the fibroblasts of normal controls induced the abnormal AD-Biomarker phenotype, suggesting the pathophysiologic relevance of this AD-Biomarker measurement. In summary, the AD-Biomarker, as confirmed by autopsy validation, showed significantly higher sensitivity and specificity than did clinical diagnosis, particularly at early stages of disease, and pathophysiological relevance was demonstrated for the mechanistic basis of the AD-Biomarker measurements.
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Affiliation(s)
- Tapan Kumar Khan
- Blanchette Rockefeller Neurosciences Institute, West Virginia University, Morgantown, WV 26506-9301, USA
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25
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Jang H, Zheng J, Lal R, Nussinov R. New structures help the modeling of toxic amyloidbeta ion channels. Trends Biochem Sci 2008; 33:91-100. [PMID: 18182298 DOI: 10.1016/j.tibs.2007.10.007] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2007] [Revised: 10/18/2007] [Accepted: 10/19/2007] [Indexed: 11/16/2022]
Abstract
The mechanism of amyloid toxicity is poorly understood and there are two schools of thought in this hotly debated field: the first favors membrane destabilization by intermediate-to-large amyloid oligomers, with consequent thinning and non-specific ion leakage; the second favors ion-specific permeable channels lined by small amyloid oligomers. Published results currently support both mechanisms. However, the amyloidbeta (Abeta) peptide has recently been shown to form a U-shaped 'beta-strand-turn-beta-strand' structure. This structure and the available physiological data present a challenge for computational biology--to provide candidate models consistent with the experimental data. Modeling based on small Abeta oligomers containing extramembranous N-termini predicts channels with shapes and dimensions consistent with experimentally derived channel structures. These results support the hypothesis that small Abeta oligomers can form ion channels. Molecular dynamics modeling can provide blueprints of 3D structural conformations for many other amyloids whose membrane association is key to their toxicity.
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Affiliation(s)
- Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick Inc. NCI-Frederick, Frederick, MD 21702, USA
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26
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Sultana R, Butterfield DA. Alterations of some membrane transport proteins in Alzheimer's disease: role of amyloid β-peptide. ACTA ACUST UNITED AC 2008; 4:36-41. [DOI: 10.1039/b715278g] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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27
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Potassium channels in hippocampal neurones are absent in a transgenic but not in a chemical model of Alzheimer's disease. Brain Res 2008; 1190:1-14. [DOI: 10.1016/j.brainres.2007.10.071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2007] [Revised: 10/19/2007] [Accepted: 10/26/2007] [Indexed: 01/02/2023]
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28
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Jang H, Zheng J, Nussinov R. Models of beta-amyloid ion channels in the membrane suggest that channel formation in the bilayer is a dynamic process. Biophys J 2007; 93:1938-49. [PMID: 17526580 PMCID: PMC1959551 DOI: 10.1529/biophysj.107.110148] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Here we model the Alzheimer beta-peptide ion channel with the goal of obtaining insight into the mechanism of amyloid toxicity. The models are built based on NMR data of the oligomers, with the universal U-shaped (strand-turn-strand) motif. After 30-ns simulations in the bilayer, the channel dimensions, shapes and subunit organization are in good agreement with atomic force microscopy (AFM). The models use the Abeta(17-42) pentamer NMR-based coordinates. Extension and bending of the straight oligomers lead to two channel topologies, depending on the direction of the curvature: 1), the polar/charged N-terminal beta-strand of Abeta(17-42) faces the water-filled pore, and the hydrophobic C-terminal beta-strand faces the bilayer (CNpNC; p for pore); and 2), the C-terminal beta-strand faces the solvated pore (NCpCN). In the atomistic simulations in a fully solvated DOPC lipid bilayer, the first (CNpNC) channel preserves the pore and conducts solvent; by contrast, hydrophobic collapse blocks the NCpCN channel. AFM demonstrated open pores and collapsed complexes. The final averaged CNpNC pore dimensions (outer diameter 8 nm; inner diameter approximately 2.5 nm) are in the AFM range (8-12 nm; approximately 2 nm, respectively). Further, in agreement with high-resolution AFM images, during the simulations, the channels spontaneously break into ordered subunits in the bilayer; however, we also observe that the subunits are loosely connected by partially disordered inner beta-sheet, suggesting subunit mobility in the bilayer. The cationic channel has strong selective affinity for Ca(2+), supporting experimental calcium-selective beta-amyloid channels. Membrane permeability and consequent disruption of calcium homeostasis were implicated in cellular degeneration. Consequently, the CNpNC channel topology can sign cell death, offering insight into amyloid toxicity via an ion "trap-release" transport mechanism. The observed loosely connected subunit organization suggests that amyloid channel formation in the bilayer is a dynamic, fluid process involving subunit association, dissociation, and channel rearrangements.
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Affiliation(s)
- Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, National Cancer Institute-Frederick, Frederick, MD 21702, USA
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29
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Alkon DL, Sun MK, Nelson TJ. PKC signaling deficits: a mechanistic hypothesis for the origins of Alzheimer's disease. Trends Pharmacol Sci 2007; 28:51-60. [PMID: 17218018 DOI: 10.1016/j.tips.2006.12.002] [Citation(s) in RCA: 174] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 11/06/2006] [Accepted: 12/19/2006] [Indexed: 11/29/2022]
Abstract
There is strong evidence that protein kinase C (PKC) isozyme signaling pathways are causally involved in associative memory storage. Other observations have indicated that PKC signaling pathways regulate important molecular events in the neurodegenerative pathophysiology of Alzheimer's disease (AD), which is a progressive dementia that is characterized by loss of recent memory. This parallel involvement of PKC signaling in both memory and neurodegeneration indicates a common basis for the origins of both the symptoms and the pathology of AD. Here, we discuss this conceptual framework as a basis for an autopsy-validated peripheral biomarker--and for AD drug design targeting drugs (bryostatin and bryologs) that activate PKC isozymes--that has already demonstrated significant promise for treating both AD neurodegeneration and its symptomatic memory loss.
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Affiliation(s)
- Daniel L Alkon
- Blanchette Rockefeller Neurosciences Institute, 9601 Medical Center Drive, Rockville, MD 20850, USA.
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30
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Puzzo D, Palmeri A, Arancio O. Involvement of the nitric oxide pathway in synaptic dysfunction following amyloid elevation in Alzheimer's disease. Rev Neurosci 2007; 17:497-523. [PMID: 17180876 DOI: 10.1515/revneuro.2006.17.5.497] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Amyloid-beta (Abeta), a peptide thought to play a crucial role in Alzheimer's disease (AD), has attracted scientific interest with the aim of characterizing the mechanisms by which it is involved in AD pathogenesis. Abeta has been found to markedly impair hippocampal long-term potentiation (LTP), a widely studied cellular model of synaptic plasticity that is thought to underlie learning and memory. The overall purpose of this review is to define the role of the nitric oxide (NO)/cGMP/cAMP-regulatory element binding (CREB) pathway in beta-amyloid-induced changes of basal neurotransmission and synaptic plasticity in the hippocampus, a structure within the temporal lobe of the brain critical for memory storage.
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Affiliation(s)
- Daniela Puzzo
- Department of Pathology, Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, NY, USA.
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31
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Solntseva EI, Bukanova JV, Marchenko E, Skrebitsky VG. Donepezil is a strong antagonist of voltage-gated calcium and potassium channels in molluscan neurons. Comp Biochem Physiol C Toxicol Pharmacol 2007; 144:319-26. [PMID: 17126610 DOI: 10.1016/j.cbpc.2006.10.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Revised: 10/04/2006] [Accepted: 10/15/2006] [Indexed: 11/24/2022]
Abstract
Donepezil is an acetylcholinesterase inhibitor used in Alzheimer's disease therapy. The neuroprotective effect of donepezil has been demonstrated in a number of different models of neurodegeneration including beta-amyloid toxicity. Since the mechanisms of neurodegeneration involve the activation of both Ca(2+)- and K(+)-channels, the study of donepezil action on voltage-gated ionic currents looked advisable. In the present study, the action of donepezil on voltage-gated Ca(2+)- and K(+)-channels was investigated on isolated neurons of the edible snail (Helix pomatia) using the two-microelectrodes voltage-clamp technique. Donepezil rapidly and reversibly inhibited voltage activated Ca(2+)-current (I(Ca)) (IC(50)=7.9 microM) and three types of high threshold K(+)-current: Ca(2+)-dependent K(+)-current (I(C)) (IC(50)=6.4 microM), delayed rectifier K(+)-current (I(DR)) (IC(50)=8.0 microM) and fast transient K(+)-current (I(Adepol)) (IC(50)=9.1 microM). The drug caused a dual effect on low-threshold fast transient K(+)-current (I(A)), potentiating it at low (5 microM) concentration, but inhibiting at higher (7 microM and above) concentration. Donepezil also caused a significant hyperpolarizing shift of the voltage-current relationship of I(Ca) (but not of any type of K(+)-current). Results suggest the possible contribution of the blocking effect of donepezil on the voltage-gated Ca(2+)- and K(+)-channels to the neuroprotective effect of the drug.
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Affiliation(s)
- Elena I Solntseva
- Brain Research Institute, Russian Academy of Medical Sciences, Per. Obukha, 5, 105064, Moscow, Russia
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Momčilović B, Lykken GI, Cooley M. Natural distribution of environmental radon daughters in the different brain areas of an Alzheimer disease victim. Mol Neurodegener 2006; 1:11. [PMID: 16965619 PMCID: PMC1579210 DOI: 10.1186/1750-1326-1-11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2006] [Accepted: 09/11/2006] [Indexed: 11/26/2022] Open
Abstract
Background Radon is a ubiquitous noble gas in the environment and a primary source of harmful radiation exposure for humans; it decays in a cascade of daughters (RAD) by releasing the cell damaging high energy alpha particles. Results We studied natural distribution of RAD 210Po and 210Bi in the different parts of the postmortem brain of 86-year-old woman who had suffered from Alzheimer's disease (AD). A distinct brain map emerged, since RAD distribution was different among the analyzed brain areas. The highest RAD irradiation (mSv·year-1) occurred in the decreasing order of magnitude: amygdale (Amy) >> hippocampus (Hip) > temporal lobe (Tem) ~ frontal lobe (Fro) > occipital lobe (Occ) ~ parietal lobe (Par) > substantia nigra (SN) >> locus ceruleus (LC) ~ nucleus basalis (NB); generally more RAD accumulated in the proteins than lipids of gray and white (gray > white) brain matter. Amy and Hip are particularly vulnerable brain structure targets to significant RAD internal radiation damage in AD (5.98 and 1.82 mSv·year-1, respectively). Next, naturally occurring RAD radiation for Tem and Fro, then Occ and Par, and SN was an order of magnitude higher than that in LC and NB; the later was within RAD we observed previously in the healthy control brains. Conclusion Naturally occurring environmental RAD exposure may dramatically enhance AD deterioration by selectively targeting brain areas of emotions (Amy) and memory (Hip).
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Affiliation(s)
- Berislav Momčilović
- Institute for Medical Research and Occupational Health, PO Box 291, 10001 Zagreb, Croatia
| | - Glenn I Lykken
- Department of Physics, University of North Dakota, Grand Forks, ND 58202-7129, USA
| | - Marvin Cooley
- Department of Pathology, University of North Dakota, Grand Forks, ND 58202-7129, USA
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Qin Y, Qi JS, Qiao JT. Apolipoprotein E4 suppresses delayed-rectifier potassium channels in membrane patches excised from hippocampal neurons. Synapse 2006; 59:82-91. [PMID: 16270302 DOI: 10.1002/syn.20201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Recent studies show a clear association between Alzheimer's disease (AD) and the apolipoprotein E epsilon 4 allele (APOE4). The mechanisms underlying apoE4-mediated detrimental effects have not been well-clarified. The present study investigates possible effects of apoE4 on the delayed-rectifier potassium (IK) channels in inside-out membrane patches excised from rat hippocampal neurons. Acute application of apoE4 (0.5 microM) to the inside of the membrane patches markedly and reversibly suppressed the single IK channel activities. The average open probability and open frequency of IK channels decreased by (92.6+/-7.1)% and (88.6+/-3.2)%, respectively. The mean open time of IK channels decreased by (81.6+/-6.7)%, and the mean closed-time of them increased by 6.9+/-1.9 fold. Meanwhile, the mean current amplitude of IK channels was not significantly affected. In contrast, application of apolipoprotein A (apoA, 0.5 microM), another member of apolipoprotein family with similar molecular weight and amino acid sequence to apoE4, did not exhibit any effects on IK currents. These results indicate that apoE4 molecules can rapidly suppress the activities of IK channels in hippocampal neurons when they act on the inner side of the neuronal membrane. We propose that the overproduction of apoE4 in neurons may suppress normal IK channel activities and thus be responsible for the late-developed neuronal damages related to the pathogenesis of AD.
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Affiliation(s)
- Ying Qin
- Department of Neurobiology, Shanxi Medical University, Taiyuan, Shanxi 030001, People's Republic of China
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McLarnon JG, Choi HB, Lue LF, Walker DG, Kim SU. Perturbations in calcium-mediated signal transduction in microglia from Alzheimer's disease patients. J Neurosci Res 2005; 81:426-35. [PMID: 15948178 DOI: 10.1002/jnr.20487] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Calcium-sensitive fluorescence microscopy has been used to study Ca2+-dependent signal transduction pathways in microglia obtained from Alzheimer's disease (AD) patients and non-demented (ND) individuals. Data were obtained from nine AD cases and seven ND individuals and included basal levels of intracellular Ca2+ [Ca2+]i, peak amplitudes (Delta[Ca2+]i) and time courses of adenosine triphosphate (ATP) responses and amplitudes of an initial transient response and a subsequent second component of Ca2+ influx through store-operated channels (SOC) induced by platelet-activating factor (PAF). Overall, AD microglia were characterized by significantly higher (20%) basal Ca2+ [Ca2+]i relative to ND cells. The Delta[Ca2+]i of ATP and initial phase of PAF responses, which reflect rapid depletion of Ca2+ from endoplasmic reticulum stores, were reduced by respective values of 63% and 59% in AD cells relative to amplitudes recorded from ND microglia. Additionally, AD microglia showed diminished amplitudes (reduction of 61%) of SOC-mediated Ca2+ entry induced by PAF and prolonged time courses (increase of 60%) of ATP responses with respect to ND microglia. We have generally replicated these results with exposure of human fetal microglia to beta amyloid (5 microM Abeta1-42 applied for 24 hr). Overall, these data indicate significant abnormalities are present in Ca2+-mediated signal transduction in microglia isolated from AD patients.
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Affiliation(s)
- James G McLarnon
- Department of Pharmacology and Therapeutics, Faculty of Medicine, University of British Columbia, Vancouver, British Columbia, Canada.
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36
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Sun XD, Mo ZL, Taylor BM, Epps DE. A slowly formed transient conformer of Abeta(1-40) is toxic to inward channels of dissociated hippocampal and cortical neurons of rats. Neurobiol Dis 2004; 14:567-78. [PMID: 14678772 DOI: 10.1016/j.nbd.2003.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The mechanism by which amyloid peptide (Abeta(1-40)) produces effects on neurotransmission is currently unresolved. In initial experiments, using the patch-clamp technique, we found that 11.5 microM of preaggregated Abeta(1-40) altered the hippocampal neuron resting membrane potential and inhibited action potential firing. To identify the toxic species, the effects of Abeta(1-40) on sodium (I(Na)), calcium (I(Ca)), and potassium (I(K)) currents in hippocampal neurons were examined as a function of peptide aggregation state in a specially designed miniature recording chamber. Aggregation reactions were induced by constant shaking, starting with 50 microM monomeric peptide. At 10- to 30-min intervals, the ionic currents were examined on a single neuron suspended in control saline and then in a 100-microl sample of the aggregating peptide. We found that samples of the peptide taken 60-120 min into the aggregation process contained species that exhibited maximal inhibitory effects over a broad potential range in the rank ordering of I(Na) > I(Ca). I(K) was inhibited only slightly at depolarized potentials. Inhibition of APF through blockade of these channels would inhibit normal neuronal activity and directly contribute to cognitive dysfunction. In previous studies on SH-EP cells, we showed that neither monomeric nor fibrillar peptide had significant effect on cell viability except during exposure to the 60-120 minute aggregation product when cell death was recorded. Our kinetic model demonstrated that the toxic species was a slowly formed transient conformer (activated monomer), which was the only aggregating species that passed through a maximum concentration during aggregation. This species amounted to only a small fraction of the total amount of aggregating peptide. We conclude that, for both the native neurons in the present study as well as SH-EP1 cells, the activated monomeric conformer of the peptide is the toxic species.
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Affiliation(s)
- Xiao-Dong Sun
- Discovery Technologies Toxicology, Pharmacia Inc., 301 Henrietta Street, Kalamazoo, MI 49007, USA
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37
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Jong YJI, Dalemar LR, Seehra K, Baenziger NL. Bradykinin receptor modulation in cellular models of aging and Alzheimer's disease. Int Immunopharmacol 2002; 2:1833-40. [PMID: 12489797 DOI: 10.1016/s1567-5769(02)00168-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Human fibroblast cell culture systems have been used to model both molecular events associated with the aging process and the biochemical anomalies found in the aging-associated neurodegenerative disorder Alzheimer's disease (AD). We demonstrate modulation of bradykinin (BK) B2 receptors that results in Intermediate (I, Kd 2.5-5 nM) and Low (L, Kd 44 nM) receptor affinity states in two cellular model systems that target aging and aging-associated disorders: the human lung fibroblast cell line WI-38 model for cellular aging and a skin fibroblast cell line from a patient with early onset familial Alzheimer's disease. In both cellular models the generation of I and L BK B2 receptors is extremely rapid, occurring within 1 min of activation of protein kinase C (PKC) by phorbol ester. Blocking phosphoprotein phosphatase activity further augments the cellular content of I and L receptors in the Alzheimer's skin fibroblast cell line. These two lines of evidence suggest that a phosphorylation cascade modifying the receptors is responsible for the I and L states. The I and L receptors remain biologically active and enhance cellular responsiveness to elevated levels of BK that are found in tissue injury, one of the major risk factors for development of Alzheimer's disease. The Alzheimer's disease skin fibroblast cell line presents a cellular environment highly enriched in the amyloid Abeta1-42 peptide that is the hallmark of Alzheimer's plaque lesions in the brain. This Abeta-rich environment may serve to foster the signal transduction mechanism that generates I and L BK B2 receptors.
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Affiliation(s)
- Y J I Jong
- Department of Anatomy and Neurology, Washington University School of Medicine, 660 South Euclid Avenue, Campus Box 8108, St Louis, MO 63110, USA
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38
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Zhao WQ, Ravindranath L, Mohamed AS, Zohar O, Chen GH, Lyketsos CG, Etcheberrigaray R, Alkon DL. MAP kinase signaling cascade dysfunction specific to Alzheimer's disease in fibroblasts. Neurobiol Dis 2002; 11:166-83. [PMID: 12460556 DOI: 10.1006/nbdi.2002.0520] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mitogen-activated protein kinases (such as Erk1/2) regulate phosphorylation of the microtubule-associated protein tau and processing of the amyloid protein beta, both events critical to the pathophysiology of Alzheimer's disease (AD). Here we report that enhanced and prolonged Erk1/2 phosphorylation in response to bradykinin (BK) was detected in fibroblasts of both familial and sporadic AD, but not age-matched controls (AC). The AD-associated abnormality in Erk1/2 phosphorylation was not seen in fibroblasts from Huntington's disease patients with dementia. The elevation of Erk1/2 phosphorylation occurred immediately after BK stimulation and required an IP3-sensitive Ca(2+) release as well as activation of PKC and c-src as upstream events. Treatment of cells with the PI-3 kinase blocker LY924002 partially inhibited the BK-stimulated Erk1/2 phosphorylation in AC, but had no effect in AD cells, suggesting that the BK-induced Erk1/2 phosphorylation in AD cells is independent of PI-3 kinase. Activation of the cAMP-responsive element binding protein (CREB) monitored as an increase in phosphorylation at Ser-133 was also observed after BK stimulation. Unlike the AD-specific differences for Erk1/2, however, the BK-stimulated CREB phosphorylation was not different between AC and AD cells. Abnormal Erk1/2 activities may alter downstream cellular processes such as gene transcription, amyloid precursor protein processing, and tau protein phosphorylation, which contribute to the pathogenesis of AD. Moreover, detection of AD-specific differences in MAP kinase in peripheral tissues may provide an efficient means for early diagnosis of AD as well as help us to identify therapeutic targets for drug discovery.
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Affiliation(s)
- Wei-Qin Zhao
- Laboratory of Adaptive Systems, National Institute of Neurological Disorder and Stroke, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Tran MH, Yamada K, Nabeshima T. Amyloid beta-peptide induces cholinergic dysfunction and cognitive deficits: a minireview. Peptides 2002; 23:1271-83. [PMID: 12128084 DOI: 10.1016/s0196-9781(02)00062-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amyloid beta-peptide (Abeta) plays a critical role in the development of Alzheimer's disease (AD). Much progress has been made in understanding this age-related neurodegenerative disorder, thus an insight into the cellular actions of Abeta and resulting functional consequences may contribute to preventive and therapeutic approaches for AD. In this review, recent evidence of Abeta-induced brain dysfunction, particularly of cholinergic impairment and memory deficits is summarized. Moreover, proposed mechanisms for Abeta-induced neurotoxicity such as oxidative stress, ion-channel formation, and Abeta-receptor interaction are discussed.
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Affiliation(s)
- Manh Hung Tran
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya 466-8560, Japan
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40
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Xu XH, Pan YP, Wang XL. mRNA expression alterations of inward rectifier potassium channels in rat brain with cholinergic impairment. Neurosci Lett 2002; 322:25-8. [PMID: 11958835 DOI: 10.1016/s0304-3940(02)00071-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Potassium channel dysfunction has been indicated in Alzheimer's disease. In the present study, spatial memory, the activity of cortical acetylcholinesterase (AChE) and the expressions of inward rectifier potassium channels (Kir) were measured after ibotenic acid lesions of nucleus basalis magnocellularis (nbm) in rats. Expressions of Kir (Kir2.1, Kir3.1, Kir6.1 and Kir6.2) at mRNA level were assessed using reverse transcription-polymerase chain reaction. At 28 days after ibotenic acid injection, the spatial memory of rats was significantly impaired accompanied by a 32% reduction of cortical AChE activity. Furthermore, the expression of Kir6.2 was increased by 79.3% in cortex, and that of Kir6.1 was increased by 172.1% in hippocampus, while no obvious changes in the mRNA expression of Kir2.1 and Kir3.1 were detected. This study indicated that the expression of adenosine triphosphate-sensitive potassium channel was area and channel subtype specifically increased following nbm lesions.
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Affiliation(s)
- Xiang-Hua Xu
- Department of Pharmacology, Institute of Materia Medica, Peking Union Medical College and Chinese Academy of Medical Sciences, 1 Xiannongtan Street, Beijing 100050, China
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41
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Kalanj-Bognar S, Rundek T, Furac I, Demarin V, Cosović C. Leukocyte lysosomal enzymes in Alzheimer's disease and Down's syndrome. J Gerontol A Biol Sci Med Sci 2002; 57:B16-21. [PMID: 11773202 DOI: 10.1093/gerona/57.1.b16] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Previous studies suggested the possibility of accelerated lysosomal degradation of brain gangliosides in Alzheimer's disease (AD). As AD pathology affects both neural and nonneural tissues, the aim of this study was to determine possible changes of glycosphingolipid metabolism in available peripheral cells in AD and Down's syndrome (DS). The activities of several lysosomal enzymes involved in catabolism of gangliosides and sulfatides were measured in leukocytes from subjects with dementia of the Alzheimer type, DS, and age-matched controls, by fluorimetry and spectrophotometry using specific substrates. The results showed a statistically significant increase of beta-galactosidase activity in both dementia of the Alzheimer type and DS leukocytes when compared with age-matched controls (p <.01 and p <.05, respectively; Student's t test). Not significantly increased activities of beta-galactosidase, beta-hexosaminidase, beta-hexosaminidase A, and slightly decreased activity of arylsulfatase A were observed in control leukocytes with aging. Our results indicate that a metabolic dysfunction and the acceleration of at least some lysosomal catabolic pathways are present in AD and DS nonneural cells.
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42
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Botta L, Valli P, Asti A, Perin P, Zucca G, Racchi M, Govoni S, Pascale A. beta amyloid-induced disruption of ionic balance: studies on the isolated frog labyrinth. Neuroreport 2001; 12:2493-7. [PMID: 11496136 DOI: 10.1097/00001756-200108080-00041] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The beta-amyloid peptide (A beta) is a key player in the pathogenesis of Alzheimer's disease. Although its mechanisms of action are not fully elucidated, a disruption of ionic homeostasis has been suggested, and A beta aggregation in fibrils seems correlated to its toxic potential. In the present work, we studied the effects of different A beta fragments on the activity of frog ampullar nerve fibers. Our results show that A beta fragments are able to reduce ampullar nerve responses, with a potency correlated to their fibrillogenic capability. This study may have clinical implications, since vestibular problems are often reported in Alzheimer patients, and provide a model for the dissection of A beta effects in a simple multicomponent system.
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Affiliation(s)
- L Botta
- Department of Cell and Molecular Physiological and Pharmacological Sciences, Via Forlanini 6, University of Pavia, 27100 Pavia, Italy
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43
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Chang SW, Zhang D, Chung HD, Zassenhaus HP. The frequency of point mutations in mitochondrial DNA is elevated in the Alzheimer's brain. Biochem Biophys Res Commun 2000; 273:203-8. [PMID: 10873587 DOI: 10.1006/bbrc.2000.2885] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Using a PCR-based strategy, we found that point mutation frequencies in mitochondrial DNA (mtDNA) were 2- to 3-fold higher in the parietal gyrus, hippocampus, and cerebellum from subjects with Alzheimer's disease (AD) compared to normal controls. In contrast, levels of a commonly studied deletion mutation, mtDNA(4977), were not elevated in AD. The frequency of point mutations did not vary significantly among the three brain areas, whereas the frequency of mtDNA(4977) was 15- to 25-fold lower in the cerebellum in comparison to the cortex; this regional variation was seen in both the normal and Alzheimer's brain. In blood mtDNA, point mutation frequencies were not elevated in AD patients. The elevated frequency of point mutations in all three brain regions is consistent with the idea that increased oxidant stress is associated with AD.
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Affiliation(s)
- S W Chang
- Department of Molecular Microbiology and Immunology, Department of Pathology, St. Louis University Health Sciences Center, 1402 South Grand Boulevard, St. Louis, Missouri 63104, USA
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Itoh A, Akaike T, Sokabe M, Nitta A, Iida R, Olariu A, Yamada K, Nabeshima T. Impairments of long-term potentiation in hippocampal slices of beta-amyloid-infused rats. Eur J Pharmacol 1999; 382:167-75. [PMID: 10556667 DOI: 10.1016/s0014-2999(99)00601-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this study, we investigated the neuronal activity of hippocampal slices from the beta-amyloid protein-infused (300 pmol/day for 10-11 days) rats using the extracellular recording technique. Perfusion of nicotine (50 microM) reduced the amplitude of electrically evoked population spikes in the CA1 pyramidal cells of the vehicle control rats, but not in those of the beta-amyloid protein-infused rats, suggesting the impairment of nicotinic signaling in the beta-amyloid protein-infused rats. Long-term potentiation induced by tetanic stimulations in CA1 pyramidal cells, which was readily observed in the vehicle control rats, was also impaired in the beta-amyloid protein-infused rats. Nicotinic blockade by adding hexamethonium into the perfused solution inhibited long-term potentiation induction. Taken together, our previous and present results suggest that beta-amyloid protein infusion impairs the signal transduction mechanisms via nicotinic acetylcholine receptors. This dysfunction may be responsible, at least in part, for the impairment of long-term potentiation induction and may lead to learning deficits.
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Affiliation(s)
- A Itoh
- Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya, Japan
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45
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Etcheberrigaray R, Bhagavan S. Ionic and signal transduction alterations in Alzheimer's disease: relevance of studies on peripheral cells. Mol Neurobiol 1999; 20:93-109. [PMID: 10966116 DOI: 10.1007/bf02742436] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Several lines of evidence indicate that Alzheimer's disease (AD) has systemic expression. Systemic changes are manifested as alterations in a number of molecular and cellular processes. Although, these alterations appear to have little or no consequence in peripheral systems, their parallel expression in the central nervous system (CNS) could account for the principal clinical manifestations of the disease. Recent research seems to indicate that alterations in ion channels, calcium homeostasis, and protein kinase C (PKC) can be linked and thereby constitute a model of pathophysiological relevance. Considering the difficulties of studying dynamic pathophysiological processes in the disease-ridden postmortem AD brain, peripheral tissues such as fibroblasts provide a suitable model to study molecular and cellular aspects of the disease.
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Affiliation(s)
- R Etcheberrigaray
- Laboratory of Applied Neuroscience, Institute for Cognitive and Computational Sciences, Georgetown University Medical Center, Washington, DC, USA.
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de Silva HA, Aronson JK, Grahame-Smith DG, Jobst KA, Smith AD. Abnormal function of potassium channels in platelets of patients with Alzheimer's disease. Lancet 1998; 352:1590-3. [PMID: 9843105 DOI: 10.1016/s0140-6736(98)03200-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND Reports of abnormalities of potassium-channel function in various cultured cells of Alzheimer's disease patients led us to attempt to characterise the pharmacological characteristics of the abnormal channel. METHODS We studied platelets from 14 patients with Alzheimer-type dementia and 14 non-demented controls matched for age and sex. The effects of specific inhibitors of K+ channels on the efflux of rubidium-86 ions, a radioactive analogue of K+, from the platelets were measured. FINDINGS Normal platelets contain three types of K+ channel, sensitive to the inhibitory actions of apamin (small-conductance calcium-dependent potassium channels), charybdotoxin (of less specificity, but probably intermediate-conductance calcium-dependent K+ channels), and alpha-dendrotoxin (voltage-sensitive K+ channels). However, 8Rb+ efflux from the platelets of patients with Alzheimer-type dementia was not inhibited by either apamin or charybdotoxin. By contrast, inhibition by alpha-dendrotoxin did occur. INTERPRETATION Our results suggest that calcium-dependent K+ channels in platelets are selectively impaired in Alzheimer's disease. A similar abnormality in neurons could contribute to the pathophysiology of the disorder.
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Affiliation(s)
- H A de Silva
- University Department of Clinical Pharmacology, Radcliffe Infirmary, Oxford, UK
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47
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Garlind A, Nilsson E, Palmblad J. Calcium ion transients in neutrophils from patients with sporadic Alzheimer's disease. Neurosci Lett 1998; 255:95-8. [PMID: 9835223 DOI: 10.1016/s0304-3940(98)00716-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Abnormalities involving intracellular calcium homeostasis have been detected in Alzheimer's disease brain and fibroblasts as well as presenilin-1 mutation-bearing cells. In the present study we investigated inositol(1,4,5)trisphosphate-mediated calcium transients as well as calcium responses via mechanisms not related to surface receptors in Alzheimer's disease polymorphonuclear (PMN) granulocytes, using the tripeptide formyl-methionyl-leucyl-phenyl alanine (fMLP) and calcium ionophore ionomycin, respectively. fMLP elicited a biphasic response with an initial, fast increase in intracellular free calcium concentrations followed by a second, lower phase with no significant differences in either maximal response or time course between Alzheimer's disease granulocytes and controls. Similarly, the calcium signal elicited after ionomycin exposure was unchanged in Alzheimer's disease PMN. In conclusion, these results indicate that calcium mobilization from intracellular stores and via cross-membrane mechanisms is intact in Alzheimer's disease granulocytes.
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Affiliation(s)
- A Garlind
- Department of Clinical Neuroscience and Family Medicine, Karolinska Institute, Huddinge University Hospital, Sweden
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48
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Bhagavan S, Ibarreta D, Ma D, Kozikowski AP, Etcheberrigaray R. Restoration of TEA-induced calcium responses in fibroblasts from Alzheimer's disease patients by a PKC activator. Neurobiol Dis 1998; 5:177-87. [PMID: 9848089 DOI: 10.1006/nbdi.1998.0195] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Several alterations in fibroblasts of Alzheimer's disease (AD) patients have been described, including alterations in calcium regulation, protein kinase C (PKC), and potassium (K+) channels. Studies have also found reduced levels of the alpha isoform of PKC in brains and fibroblasts of AD patients. Since PKC is known to regulate ion channels, we studied K+ channel activity in fibroblasts from AD patients in the presence of (2S, 5S)-8-(1-decynyl)benzolactam (BL), a novel activator of PKC with improved selectivity for the alpha, beta, and gamma isoforms. We present evidence for restoration of normal K+ channel function, as measured by TEA-induced [Ca2+]i elevations, due to activation of PKC by BL. Representative patch-clamp data further substantiate the effect of BL on restoration of 113pS K+ channel activity. Immunoblotting analyses using an alpha-isozyme-specific PKC antibody confirm that BL-treated fibroblasts of AD patients show increased PKC activation. The present study suggests that PKC activator-based restoration of K+ channels may offer another approach to the investigation of AD pathophysiology, which in turn could lead to the development of a useful model for AD therapeutics.
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Affiliation(s)
- S Bhagavan
- Laboratory of Applied Neuroscience, Georgetown University Medical Center, Washington, DC 20007-2197, USA
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49
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Paoletti F, Tombaccini D. Proteolytic imbalance in Alzheimer fibroblasts as potential pathological trait of disease. FASEB J 1998; 12:925-7. [PMID: 9707164 DOI: 10.1096/fasebj.12.11.925] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- F Paoletti
- Istituto di Patologia Generale, Università di Firenze, Italy.
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50
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Etcheberrigaray R, Hirashima N, Nee L, Prince J, Govoni S, Racchi M, Tanzi RE, Alkon DL. Calcium responses in fibroblasts from asymptomatic members of Alzheimer's disease families. Neurobiol Dis 1998; 5:37-45. [PMID: 9702786 DOI: 10.1006/nbdi.1998.0176] [Citation(s) in RCA: 118] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously identified alterations of K+ channel function, IP3-mediated calcium release, and Cp20 (a memory-associated GTP binding protein) in fibroblasts from Alzheimer's disease (AD) patients vs controls. Some of these alterations can be integrated into an index that distinguishes AD patients from controls with both high specificity and high sensitivity. We report here that alterations in IP3-mediated calcium responses are present in a large proportion of AD family members (i.e., individuals at high risk) before clinical symptoms of Alzheimer's disease are present. This was not the case if such members later "escaped" AD symptoms. This preclinical calcium signal correlate of later AD does not reflect, however, the presence of the PS1 familial AD gene.
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Affiliation(s)
- R Etcheberrigaray
- Laboratory of Applied Neuroscience, Georgetown University Medical Center, NW Washington, DC 20007, USA.
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