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Forloni G. Alpha Synuclein: Neurodegeneration and Inflammation. Int J Mol Sci 2023; 24:ijms24065914. [PMID: 36982988 PMCID: PMC10059798 DOI: 10.3390/ijms24065914] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/14/2023] [Accepted: 03/15/2023] [Indexed: 03/30/2023] Open
Abstract
Alpha-Synuclein (α-Syn) is one of the most important molecules involved in the pathogenesis of Parkinson's disease and related disorders, synucleinopathies, but also in several other neurodegenerative disorders with a more elusive role. This review analyzes the activities of α-Syn, in different conformational states, monomeric, oligomeric and fibrils, in relation to neuronal dysfunction. The neuronal damage induced by α-Syn in various conformers will be analyzed in relation to its capacity to spread the intracellular aggregation seeds with a prion-like mechanism. In view of the prominent role of inflammation in virtually all neurodegenerative disorders, the activity of α-Syn will also be illustrated considering its influence on glial reactivity. We and others have described the interaction between general inflammation and cerebral dysfunctional activity of α-Syn. Differences in microglia and astrocyte activation have also been observed when in vivo the presence of α-Syn oligomers has been combined with a lasting peripheral inflammatory effect. The reactivity of microglia was amplified, while astrocytes were damaged by the double stimulus, opening new perspectives for the control of inflammation in synucleinopathies. Starting from our studies in experimental models, we extended the perspective to find useful pointers to orient future research and potential therapeutic strategies in neurodegenerative disorders.
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Affiliation(s)
- Gianluigi Forloni
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Via Mario Negri 2, 20156 Milano, Italy
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Kawahara M, Kato-Negishi M, Tanaka KI. Neurometals in the Pathogenesis of Prion Diseases. Int J Mol Sci 2021; 22:ijms22031267. [PMID: 33525334 PMCID: PMC7866166 DOI: 10.3390/ijms22031267] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 01/25/2021] [Accepted: 01/25/2021] [Indexed: 12/29/2022] Open
Abstract
Prion diseases are progressive and transmissive neurodegenerative diseases. The conformational conversion of normal cellular prion protein (PrPC) into abnormal pathogenic prion protein (PrPSc) is critical for its infection and pathogenesis. PrPC possesses the ability to bind to various neurometals, including copper, zinc, iron, and manganese. Moreover, increasing evidence suggests that PrPC plays essential roles in the maintenance of homeostasis of these neurometals in the synapse. In addition, trace metals are critical determinants of the conformational change and toxicity of PrPC. Here, we review our studies and other new findings that inform the current understanding of the links between trace elements and physiological functions of PrPC and the neurotoxicity of PrPSc.
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Forloni G, La Vitola P, Cerovic M, Balducci C. Inflammation and Parkinson's disease pathogenesis: Mechanisms and therapeutic insight. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2020; 177:175-202. [PMID: 33453941 DOI: 10.1016/bs.pmbts.2020.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
After Alzheimer's disease, Parkinson's disease is the most frequent neurodegenerative disorder. Although numerous treatments have been developed to control the disease symptomatology, with some successes, an efficacious therapy affecting the causes of PD is still a goal to pursue. The genetic evidence and the identification of α-synuclein as the main component of intracellular Lewy bodies, the neuropathological hallmark of PD and related disorders, have changed the approach to these disorders. More recently, the detrimental role of α-synuclein has been further extended to explain the wide spread of cerebral pathology through its oligomers. To emphasize the central pathogenic role of these soluble aggregates, we have defined synucleinopathies and other neurodegenerative disorders associated with protein misfolding as oligomeropathies. Another common element in the pathogenesis of oligomeropathies is the role played by inflammation, both at the peripheral and cerebral levels. In the brain parenchyma, inflammatory reaction has been considered an obvious consequence of neuronal degeneration, but recent observations indicate a direct contribution of glial alteration in the early phase of the disease. Furthermore, systemic inflammation also influences the development of neuronal dysfunction caused by specific elements, β amyloid, α-synuclein, tau or prion. However, each disorder has its own specific pathological process and within the same pathological condition, it is possible to find inter-individual differences. This heterogeneity might explain the difficulties developing efficacious therapeutic approaches, even though the possibility of intervention is supported by robust biological evidence. We have recently demonstrated that peripheral inflammation can amplify the neuronal dysfunction induced by α-synuclein oligomers and the neuropathological consequences observed in a Parkinson's disease model. In both cases, activation of microglia was incremented by the "double hit" process, compared to the single treatment. In contrast, astrocyte activation was attenuated and these cells appeared damaged when chronic inflammation was combined with α-synuclein exposure. This evidence might indicate a more specific anti-inflammatory strategy rather than the generic anti-inflammatory treatment.
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Affiliation(s)
- Gianluigi Forloni
- Biology of Neurodegenerative Diseases, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy.
| | - Pietro La Vitola
- Biology of Neurodegenerative Diseases, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
| | - Milica Cerovic
- Biology of Neurodegenerative Diseases, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
| | - Claudia Balducci
- Biology of Neurodegenerative Diseases, Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Milano, Italy
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EA at PC6 Promotes Gastric Motility: Role of Brainstem Vagovagal Neurocircuits. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2019; 2019:7457485. [PMID: 31379967 PMCID: PMC6662446 DOI: 10.1155/2019/7457485] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Revised: 05/28/2019] [Accepted: 07/03/2019] [Indexed: 12/14/2022]
Abstract
Background We aimed to assess whether electroacupuncture (EA) at PC6 affects gastric motility via the vagovagal reflex and if so whether brainstem vagovagal neurocircuits and related transmitters are involved. Methods Gastric motility was measured in male Sprague-Dawley (SD) rats by placing a small manometric balloon in the gastric antrum. The rats were subjected to control, sham surgery, vagotomy, sympathectomy, and microinjection group, including artificial cerebrospinal fluid, gamma-aminobutyric acid (GABA), and glutamic acid (L-Glu). The effect of EA at PC6 on gastric motility was measured. Moreover, electrophysiological testing was used to measure the effect of EA at PC6 on the parasympathetic and sympathetic nerves. In addition, artificial cerebrospinal fluid, L-Glu, and GABA have been microinjected into the dorsal motor nucleus of the vagus (DMV) to measure the changes in gastric motility and parasympathetic nerve discharge induced by EA at PC6. Key Results EA facilitated the gastric motility in control group. In the vagotomy group, gastric motility was not affected by EA at PC6. However, in the sympathectomy group, gastric motility was similar to control group. Acupuncture at PC6 increased parasympathetic nerve discharge but not sympathetic nerve discharge. Furthermore, the microinjection of L-Glu into the DMV increased gastric motility, although EA at PC6 showed no remarkable change in this group. The injection of GABA reduced gastric motility and parasympathetic nerve discharge, but EA at PC6 significantly increased gastric motility and the parasympathetic nerve discharge in this group. Conclusions and Inferences EA at PC6—primarily by inhibiting GABA transmission to DMV—reduced the inhibition of efferent vagal motor fibers and thus promoted efferent vagus nerve activity and increased gastric motility.
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Mechanism of aggregation and membrane interactions of mammalian prion protein. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018. [DOI: 10.1016/j.bbamem.2018.02.031] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Ke PC, Sani MA, Ding F, Kakinen A, Javed I, Separovic F, Davis TP, Mezzenga R. Implications of peptide assemblies in amyloid diseases. Chem Soc Rev 2017; 46:6492-6531. [PMID: 28702523 PMCID: PMC5902192 DOI: 10.1039/c7cs00372b] [Citation(s) in RCA: 239] [Impact Index Per Article: 34.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Neurodegenerative disorders and type 2 diabetes are global epidemics compromising the quality of life of millions worldwide, with profound social and economic implications. Despite the significant differences in pathology - much of which are poorly understood - these diseases are commonly characterized by the presence of cross-β amyloid fibrils as well as the loss of neuronal or pancreatic β-cells. In this review, we document research progress on the molecular and mesoscopic self-assembly of amyloid-beta, alpha synuclein, human islet amyloid polypeptide and prions, the peptides and proteins associated with Alzheimer's, Parkinson's, type 2 diabetes and prion diseases. In addition, we discuss the toxicities of these amyloid proteins based on their self-assembly as well as their interactions with membranes, metal ions, small molecules and engineered nanoparticles. Through this presentation we show the remarkable similarities and differences in the structural transitions of the amyloid proteins through primary and secondary nucleation, the common evolution from disordered monomers to alpha-helices and then to β-sheets when the proteins encounter the cell membrane, and, the consensus (with a few exceptions) that off-pathway oligomers, rather than amyloid fibrils, are the toxic species regardless of the pathogenic protein sequence or physicochemical properties. In addition, we highlight the crucial role of molecular self-assembly in eliciting the biological and pathological consequences of the amyloid proteins within the context of their cellular environments and their spreading between cells and organs. Exploiting such structure-function-toxicity relationship may prove pivotal for the detection and mitigation of amyloid diseases.
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Affiliation(s)
- Pu Chun Ke
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Marc-Antonie Sani
- School of Chemistry, Bio21 Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Feng Ding
- Department of Physics and Astronomy, Clemson University, Clemson, SC 29634, United States
| | - Aleksandr Kakinen
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Ibrahim Javed
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
| | - Frances Separovic
- School of Chemistry, Bio21 Institute, The University of Melbourne, 30 Flemington Rd, Parkville, VIC 3010, Australia
| | - Thomas P. Davis
- ARC Center of Excellence in Convergent Bio-Nano Science and Technology, Monash Institute of Pharmaceutical Sciences, Monash University, 381 Royal Parade, Parkville, VIC 3052, Australia
- Department of Chemistry, University of Warwick, Gibbet Hill, Coventry, CV4 7AL, United Kingdom
| | - Raffaele Mezzenga
- ETH Zurich, Department of Health Science & Technology, Schmelzbergstrasse 9, LFO, E23, 8092 Zurich, Switzerland
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Sabareesan AT, Singh J, Roy S, Udgaonkar JB, Mathew MK. The Pathogenic A116V Mutation Enhances Ion-Selective Channel Formation by Prion Protein in Membranes. Biophys J 2017; 110:1766-1776. [PMID: 27119637 DOI: 10.1016/j.bpj.2016.03.017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Revised: 02/23/2016] [Accepted: 03/07/2016] [Indexed: 11/19/2022] Open
Abstract
Prion diseases are a group of fatal neurodegenerative disorders that afflict mammals. Misfolded and aggregated forms of the prion protein (PrP(Sc)) have been associated with many prion diseases. A transmembrane form of PrP favored by the pathogenic mutation A116V is associated with Gerstmann-Sträussler-Scheinker syndrome, but no accumulation of PrP(Sc) is detected. However, the role of the transmembrane form of PrP in pathological processes leading to neuronal death remains unclear. This study reports that the full-length mouse PrP (moPrP) significantly increases the permeability of living cells to K(+), and forms K(+)- and Ca(2+)-selective channels in lipid membranes. Importantly, the pathogenic mutation A116V greatly increases the channel-forming capability of moPrP. The channels thus formed are impermeable to sodium and chloride ions, and are blocked by blockers of voltage-gated ion channels. Hydrogen-deuterium exchange studies coupled with mass spectrometry (HDX-MS) show that upon interaction with lipid, the central hydrophobic region (109-132) of the protein is protected against exchange, making it a good candidate for inserting into the membrane and lining the channel. HDX-MS also shows a dramatic increase in the protein-lipid stoichiometry for A116V moPrP, providing a rationale for its increased channel-forming capability. The results suggest that ion channel formation may be a possible mechanism of PrP-mediated neurodegeneration by the transmembrane forms of PrP.
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Affiliation(s)
- Ambadi Thody Sabareesan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Jogender Singh
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India
| | - Samrat Roy
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India; Biocon Bristol Myers Squibb Research Center, Bengaluru, India; School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT) University, Bhubaneswar, India
| | - Jayant B Udgaonkar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
| | - M K Mathew
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bengaluru, India.
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Xu F, Tan Y, Huang Z, Zhang N, Xu Y, Yin J. Ameliorating Effect of Transcutaneous Electroacupuncture on Impaired Gastric Accommodation in Patients with Postprandial Distress Syndrome-Predominant Functional Dyspepsia: A Pilot Study. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE : ECAM 2015; 2015:168252. [PMID: 26064155 PMCID: PMC4433673 DOI: 10.1155/2015/168252] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2014] [Accepted: 09/02/2014] [Indexed: 12/14/2022]
Abstract
Patients with functional dyspepsia (FD) have both reduced gastric accommodation and impaired gastric motility that are difficult to treat. The aim of this study was to investigate the therapeutic potential of transcutaneous electroacupuncture (TEA) for both of these disorders in FD patients. Acute experiments were performed in FD patients to study the effect of TEA and sham-TEA on gastric accommodation assessed by a nutrient drink test and gastric motility assessed by the measurement of the electrogastrogram (EGG). TEA or sham-TEA was performed via cutaneous electrodes at acupoints ST36 and PC6 or sham-points nonacupoints. It was found that (1) gastric accommodation (maximum tolerable volume) was reduced in FD patients compared with the controls (P < 0.03). TEA improved gastric accommodation in FD patients (P < 0.02). (2) Acute TEA significantly increased the percentage and power of normal gastric slow waves in the fed state assessed in the FD patients by the EGG in comparison with sham-TEA. (3) TEA increased vagal activity assessed by the spectral analysis of the heart rate variability in the fed state in FD patients. It was concluded that needleless method of transcutaneous electroacupuncture may have a therapeutic potential for treating both impaired gastric accommodation and impaired gastric motility in patients with FD.
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Affiliation(s)
- Feng Xu
- Division of Gastroenterology, Yinzhou Hospital Affiliated to Medical School of Ningbo University, Ningbo 315000, China
| | - Yan Tan
- Division of Gastroenterology, Affiliated Hospital of Hainan Medical College, Haikou 571000, China
- Ningbo Pace Translational Medical Research Center, Beilun, Ningbo 315000, China
| | - Zhihui Huang
- Ningbo Pace Translational Medical Research Center, Beilun, Ningbo 315000, China
- Department of Gastroenterology, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, Hangzhou 310000, China
| | - Nina Zhang
- Ningbo Pace Translational Medical Research Center, Beilun, Ningbo 315000, China
| | - Yuemei Xu
- Division of Gastroenterology, Yinzhou Hospital Affiliated to Medical School of Ningbo University, Ningbo 315000, China
| | - Jieyun Yin
- Ningbo Pace Translational Medical Research Center, Beilun, Ningbo 315000, China
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Chapron Y, Charlet L, Sahai N. Fate of pathological prion (PrP(sc)92-138) in soil and water: prion-clay nanoparticle molecular dynamics. J Biomol Struct Dyn 2013; 32:1802-16. [PMID: 24152238 DOI: 10.1080/07391102.2013.836461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Pathogenic prion protein scrapie (PrP(sc)) may contaminate soils for decades and remain in water in colloidal suspension, providing infection pathways for animals through the inhalation of ingested dust and soil particles, and drinking water. We used molecular dynamics simulations to understand the strong binding mechanism of this pathogenic peptide with clay mineral surfaces and compared our results to experimental works. We restricted our model to the moiety PrP(92-138), which is a portion of the whole PrP(sc) molecule responsible for infectivity and modeled it using explicit solvating water molecules in contact with a pyrophyllite cleavage plane. Pyrophyllite is taken as a model for common soil clay, but it has no permanent structural charge. However, partial residual negative charges occur on the cleavage plane slab surface due to a slab charge unbalance. The charge is isotropic in 2D and it was balanced with K(+) ions. After partially removing potassium ions, the peptide anchors to the clay surface via up to 10 hydrogen bonds, between protonated lysine or histidine residues and the oxygen atoms of the siloxane cavities. Our results provide insight to the mechanism responsible for the strong association between the PrP(sc) peptide and clay nanoparticles and the associations present in contaminated soil and water which may lead to the infection of animals.
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Affiliation(s)
- Yves Chapron
- a AIED, Research , 108 rue du puy, La Terrasse , 38660 , France
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Effect of Electroacupuncture at ST36 on Gastric-Related Neurons in Spinal Dorsal Horn and Nucleus Tractus Solitarius. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:912898. [PMID: 24191172 PMCID: PMC3804039 DOI: 10.1155/2013/912898] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Accepted: 09/02/2013] [Indexed: 12/16/2022]
Abstract
The aim of this study was to observe the effect of electroacupuncture (EA) at the ST36 acupoint on the firing rate of gastric-related neurons in the spinal dorsal horn (SDH) and nucleus tractus solitarius (NTS). There were different effects of gastric distention in SDH and NTS in 46 male Sprague-Dawley rats. In 10 excitatory neurons in SDH, most of the neurons were inhibited by homolateral EA. The firing rates decreased significantly (P < 0.05) in 10 excitatory gastric-related neurons in NTS; the firing rates of 6 neurons were further excited by homolateral EA, with a significant increase of the firing rates (P < 0.05); all inhibitory gastric-related neurons in NTS were excited by EA. The inhibition rate of homolateral EA was significantly increased in comparison with contralateral EA in gastric-related neurons of SDH (P < 0.05). There was no significant difference between homolateral and contralateral EA in gastric-related neurons of NTS. EA at ST36 changes the firing rate of gastric-related neurons in SDH and NTS. However, there are some differences in responsive mode in these neurons. The existence of these differences could be one of the physiological foundations of diversity and complexity in EA effects.
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Vilches S, Vergara C, Nicolás O, Sanclimens G, Merino S, Varón S, Acosta GA, Albericio F, Royo M, Río JAD, Gavín R. Neurotoxicity of prion peptides mimicking the central domain of the cellular prion protein. PLoS One 2013; 8:e70881. [PMID: 23940658 PMCID: PMC3733940 DOI: 10.1371/journal.pone.0070881] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 06/25/2013] [Indexed: 12/20/2022] Open
Abstract
The physiological functions of PrP(C) remain enigmatic, but the central domain, comprising highly conserved regions of the protein may play an important role. Indeed, a large number of studies indicate that synthetic peptides containing residues 106-126 (CR) located in the central domain (CD, 95-133) of PrP(C) are neurotoxic. The central domain comprises two chemically distinct subdomains, the charge cluster (CC, 95-110) and a hydrophobic region (HR, 112-133). The aim of the present study was to establish the individual cytotoxicity of CC, HR and CD. Our results show that only the CD peptide is neurotoxic. Biochemical, Transmission Electron Microscopy and Atomic Force Microscopy experiments demonstrated that the CD peptide is able to activate caspase-3 and disrupt the cell membrane, leading to cell death.
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Affiliation(s)
- Silvia Vilches
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| | - Cristina Vergara
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
| | - Oriol Nicolás
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Gloria Sanclimens
- Combinatorial Chemistry Unit, Scientific Park of Barcelona, Barcelona, Spain
| | - Sandra Merino
- Department of Physicochemistry, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain
| | - Sonia Varón
- Combinatorial Chemistry Unit, Scientific Park of Barcelona, Barcelona, Spain
| | - Gerardo A. Acosta
- Institute for Research in Biomedicine (IRB), Barcelona, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - Fernando Albericio
- Institute for Research in Biomedicine (IRB), Barcelona, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
- Department of Organic Chemistry, Faculty of Chemistry, University of Barcelona, Barcelona, Spain
| | - Miriam Royo
- Combinatorial Chemistry Unit, Scientific Park of Barcelona, Barcelona, Spain
- Networking Research Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Barcelona, Spain
| | - José A. Del Río
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Rosalina Gavín
- Molecular and Cellular Neurobiotechnology, Institute for Bioengineering of Catalonia (IBEC), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), Barcelona, Spain
- Department of Cell Biology, Faculty of Biology, University of Barcelona, Barcelona, Spain
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"Intensity-response" effects of electroacupuncture on gastric motility and its underlying peripheral neural mechanism. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:535742. [PMID: 23935667 PMCID: PMC3713365 DOI: 10.1155/2013/535742] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 06/08/2013] [Accepted: 06/17/2013] [Indexed: 02/08/2023]
Abstract
The aim of this study was to explore the "intensity-response" relationship between EAS and the effect of gastric motility of rats and its underlying peripheral neural mechanism by employing ASIC3 knockout (ASIC3-/-), TRPV1 knockout (TRPV1-/-), and C57BL/6 mice. For adult male Sprague-Dawley (n = 18) rats, the intensities of EAS were 0.5, 1, 3, 5, 7, and 9 mA, respectively. For mice (n = 8 in each group), only 1 mA was used, by which C fiber of the mice can be activated. Gastric antrum motility was measured by intrapyloric balloon. Gastric motility was facilitated by EAS at ST36 and inhibited by EAS at CV12. The half maximal facilitation intensity of EAS at ST36 was 2.1-2.3 mA, and the half maximal inhibitory intensity of EAS at CV12 was 2.8 mA. In comparison with C57BL/6 mice, the facilitatory effect of ST36 and inhibitive effect of CV12 in ASIC3-/- mice decreased, but the difference was not statistically significant (P > 0.05). However, these effects in TRPV1-/- mice decreased significantly (P < 0.001). The results indicated that there existed an "intensity-response" relationship between EAS and the effect of gastric motility. TRPV1 receptor was involved in the regulation of gastric motility of EAS.
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Aidt FH, Hasholt LF, Christiansen M, Laursen H. Localization of A11-reactive oligomeric species in prion diseases. Histopathology 2013; 62:994-1001. [PMID: 23570304 DOI: 10.1111/his.12097] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Accepted: 01/13/2013] [Indexed: 12/16/2022]
Abstract
AIMS To investigate in prion diseases the in-situ localization of prion protein oligomers sharing a common epitope with amyloid oligomers involved in a range of neurodegenerative diseases. METHODS AND RESULTS We performed immunohistochemistry on sporadic Creutzfeldt-Jakob disease (sCJD) (n = 9) and hereditary Gerstmann-Sträussler-Scheinker disease (GSS) (n = 1) specimens with the anti-oligomer antibody A11 to determine the localization of reactive species. We found that A11 reactivity in the sCJD specimens was localized to the cerebral and cerebellar cortices both in spongiform and adjacent, non-spongiform areas, reminiscent of multicentric or diffuse plaques. In the GSS specimens, we found that staining was closely associated with kuru-like plaques, and that A11-reactive species colocalized with protease-resistant prion protein (Prp(Sc)). We also observed sporadic neuronal cytosolic staining in both types of specimen. CONCLUSIONS We confirm that intracellular and extracellular A11-reactive species are present in situ in sCJD cases and GSS, and that immunoreactivity for A11 and Prp(Sc) overlaps. We argue that the A11-reactive species are indeed composed of oligomeric Prp(Sc), and suggest that the toxic effects of Prp(Sc) oligomers could be related to the generic oligomeric conformation recognized by A11.
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Affiliation(s)
- Frederik H Aidt
- Section of Molecular Medicine, Department of Clinical Biochemistry, Immunology and Genetics, Statens Serum Institut, Copenhagen, Denmark.
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The primo vascular structures alongside nervous system: its discovery and functional limitation. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:538350. [PMID: 23606882 PMCID: PMC3626220 DOI: 10.1155/2013/538350] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Revised: 03/08/2013] [Accepted: 03/15/2013] [Indexed: 11/17/2022]
Abstract
The primo vascular structures comprising primo nodes and vessels (originally called Bonghan corpuscles and ducts, resp.) have recently been suggested to be the anatomical correlate of acupuncture, a therapeutic technique used in oriental medicine. Although the primo vascular structures have been observed in many parts of animals, including the nervous system, using anatomical methodologies, its physiological functions are still unclear. This paper summarizes the reports on the primo vascular structures, particularly in the nervous system and its surroundings, as well as the electrophysiological properties of cells in the primo nodes. In addition, recent reports examining the potential roles of the primo vascular structures in acupuncture are discussed. This review raises some fundamental questions and, at the same time, highlights the potential physiological roles of the primo vascular structures in acupuncture.
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The neural pathway of reflex regulation of electroacupuncture at orofacial acupoints on gastric functions in rats. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:753264. [PMID: 23346213 PMCID: PMC3549401 DOI: 10.1155/2012/753264] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 12/14/2012] [Accepted: 12/16/2012] [Indexed: 01/14/2023]
Abstract
Acupuncture has a reflex regulation in gastrointestinal functions, which is characterized with segment. In the present study, the neural pathway of electroacupuncture (EA) at orofacial acupoints (ST2) on gastric myoelectric activity (GMA) in rats was investigated. The results indicated that EA at ST2 facilitated spike bursts of GMA, which is similar to EA at limbs and opposite to EA at abdomen. The excitatory effect was abolished by the transaction of infraorbital nerves, dorsal vagal complex lesion, and vagotomy, respectively. In addition, microinjection of L-glutamate into the nucleus of the solitary tract (NTS) attenuated the excitatory effect. All these data suggest that the dorsal vagal complex is involved in the reflex regulation of EA at orofacial acupoints on gastric functions and NTS-dorsal motor nucleus of the vagus (DMV) inhibitory connections may be essential for it.
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NMDA Receptor-Dependent Synaptic Activity in Dorsal Motor Nucleus of Vagus Mediates the Enhancement of Gastric Motility by Stimulating ST36. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2012; 2012:438460. [PMID: 23118791 PMCID: PMC3478787 DOI: 10.1155/2012/438460] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 09/04/2012] [Accepted: 09/08/2012] [Indexed: 02/08/2023]
Abstract
Previous studies have demonstrated the efficacy of electroacupuncture at ST36 for patients with gastrointestinal motility disorders. While several lines of evidence suggest that the effect may involve vagal reflex, the precise molecular mechanism underlying this process still remains unclear. Here we report that the intragastric pressure increase induced by low frequency electric stimulation at ST36 was blocked by AP-5, an antagonist of N-methyl-D-aspartate receptors (NMDARs). Indeed, stimulating ST36 enhanced NMDAR-mediated, but not 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl)propanoic-acid-(AMPA-) receptor-(AMPAR-) mediated synaptic transmission in gastric-projecting neurons of the dorsal motor nucleus of the vagus (DMV). We also identified that suppression of presynaptic μ-opioid receptors may contribute to upregulation of NMDAR-mediated synaptic transmission induced by electroacupuncture at ST36. Furthermore, we determined that the glutamate-receptor-2a-(NR2A-) containing NMDARs are essential for NMDAR-mediated enhancement of gastric motility caused by stimulating ST36. Taken together, our results reveal an important role of NMDA receptors in mediating enhancement of gastric motility induced by stimulating ST36.
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18
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Kagan BL, Jang H, Capone R, Arce FT, Ramachandran S, Lal R, Nussinov R. Antimicrobial properties of amyloid peptides. Mol Pharm 2012; 9:708-17. [PMID: 22081976 PMCID: PMC3297685 DOI: 10.1021/mp200419b] [Citation(s) in RCA: 166] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
More than two dozen clinical syndromes known as amyloid diseases are characterized by the buildup of extended insoluble fibrillar deposits in tissues. These amorphous Congo red staining deposits known as amyloids exhibit a characteristic green birefringence and cross-β structure. Substantial evidence implicates oligomeric intermediates of amyloids as toxic species in the pathogenesis of these chronic disease states. A growing body of data has suggested that these toxic species form ion channels in cellular membranes causing disruption of calcium homeostasis, membrane depolarization, energy drainage, and in some cases apoptosis. Amyloid peptide channels exhibit a number of common biological properties including the universal U-shape β-strand-turn-β-strand structure, irreversible and spontaneous insertion into membranes, production of large heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition by Congo red, and channel blockade by zinc. Recent evidence has suggested that increased amounts of amyloids not only are toxic to its host target cells but also possess antimicrobial activity. Furthermore, at least one human antimicrobial peptide, protegrin-1, which kills microbes by a channel-forming mechanism, has been shown to possess the ability to form extended amyloid fibrils very similar to those of classic disease-forming amyloids. In this paper, we will review the reported antimicrobial properties of amyloids and the implications of these discoveries for our understanding of amyloid structure and function.
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Affiliation(s)
- Bruce L. Kagan
- Department of Psychiatry, David Geffen School of Medicine, Semel Institute for Neuroscience & Human Behavior, University of California, Los Angeles, California 90024, U.S.A
| | - Hyunbum Jang
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
| | - Ricardo Capone
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Fernando Teran Arce
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Srinivasan Ramachandran
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ratnesh Lal
- Departments of Bioengineering and of Mechanical and Aerospace Engineering and Material Science Program, University of California, San Diego, La Jolla, California 92093, U.S.A
| | - Ruth Nussinov
- Center for Cancer Research Nanobiology Program, SAIC-Frederick, Inc., NCI-Frederick, Frederick, Maryland 21702, U.S.A
- Department of Human Molecular Genetics and Biochemistry, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
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Huang T, Xu J, Xiang J, Lu Y, Chen R, Huang L, Xiao G, Sun G. PrPC interacts with potassium channel tetramerization domain containing 1 (KCTD1) protein through the PrP51-136 region containing octapeptide repeats. Biochem Biophys Res Commun 2012; 417:182-6. [DOI: 10.1016/j.bbrc.2011.11.081] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 11/16/2011] [Indexed: 12/26/2022]
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Kagan BL. Membrane pores in the pathogenesis of neurodegenerative disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2012; 107:295-325. [PMID: 22482454 DOI: 10.1016/b978-0-12-385883-2.00001-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The neurodegenerative diseases described in this volume, as well as many nonneurodegenerative diseases, are characterized by deposits known as amyloid. Amyloid has long been associated with these various diseases as a pathological marker and has been implicated directly in the molecular pathogenesis of disease. However, increasing evidence suggests that these proteinaceous Congo red staining deposits may not be toxic or destructive of tissue. Recent studies strongly implicate smaller aggregates of amyloid proteins as the toxic species underlying these neurodegenerative diseases. Despite the outward obvious differences among these clinical syndromes, there are some striking similarities in their molecular pathologies. These include dysregulation of intracellular calcium levels, impairment of mitochondrial function, and the ability of virtually all amyloid peptides to form ion-permeable pores in lipid membranes. Pore formation is enhanced by environmental factors that promote protein aggregation and is inhibited by agents, such as Congo red, which prevent aggregation. Remarkably, the pores formed by a variety of amyloid peptides from neurodegenerative and other diseases share a common set of physiologic properties. These include irreversible insertion of the pores in lipid membranes, formation of heterodisperse pore sizes, inhibition by Congo red of pore formation, blockade of pores by zinc, and a relative lack of ion selectivity and voltage dependence. Although there exists some information about the physical structure of these pores, molecular modeling suggests that 4-6-mer amyloid subunits may assemble into 24-mer pore-forming aggregates. The molecular structure of these pores may resemble the β-barrel structure of the toxics pore formed by bacterial toxins, such as staphylococcal α-hemolysin, anthrax toxin, and Clostridium perfringolysin.
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Affiliation(s)
- Bruce L Kagan
- Department of Psychiatry & Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Semel Institute for Neuroscience and Human Behavior, Los Angeles, California, USA
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21
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Paulis D, Maras B, Schininà ME, di Francesco L, Principe S, Galeno R, Abdel-Haq H, Cardone F, Florio T, Pocchiari M, Mazzanti M. The pathological prion protein forms ionic conductance in lipid bilayer. Neurochem Int 2011; 59:168-74. [PMID: 21683106 DOI: 10.1016/j.neuint.2011.04.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Revised: 04/16/2011] [Accepted: 04/18/2011] [Indexed: 11/15/2022]
Abstract
Transmissible spongiform encephalopathies (TSEs) are neurodegenerative pathologies characterized by the accumulation of amyloid fibrils mainly composed of the pathological isoform of the prion protein (PrP(TSE)). PrP(TSE) pre-amyloid fibrils are supposed to induce neurodegenerative lesions possibly through the alteration of membrane permeability. The effect of PrP(TSE) on cellular membranes has been modeled in vitro by synthetic peptides that are, however, only partially representative of PrP(TSE) isoforms found in vivo. In the present work we show that a synthetic membrane exposed to PrP27-30 extracted from TSE-infected hamster brains changes its permeability because of the formation of molecular pores that alter the conductance of the synthetic lipid bilayer. Synthetic membrane challenged with the recombinant prion peptide PrP90-231 shows a much lower conductance. Elevation of calcium ion concentration not only increases the current amplitude due to the action of both PrP27-30 and PrP90-231 on the membrane, but also amplifies the interaction of PrP90-231 with the lipid bilayer.
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Affiliation(s)
- Daniele Paulis
- Dipartimento di Scienze Biomolecolari e Biotecnologie, University of Milan, Italy
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22
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Abstract
Transmissible spongiform encephalopathies, or prion diseases, are lethal neurodegenerative disorders caused by the infectious agent named prion, whose main constituent is an aberrant conformational isoform of the cellular prion protein, PrP(C) . The mechanisms of prion-associated neurodegeneration and the physiologic function of PrP(C) are still unclear, although it is now increasingly acknowledged that PrP(C) plays a role in cell differentiation and survival. PrP(C) thus exhibits dichotomic attributes, as it can switch from a benign function under normal conditions to the triggering of neuronal death during disease. By reviewing data from models of prion infection and PrP-knockout paradigms, here we discuss the possibility that Ca(2+) is the hidden factor behind the multifaceted behavior of PrP(C) . By featuring in almost all processes of cell signaling, Ca(2+) might explain diverse aspects of PrP(C) pathophysiology, including the recently proposed one in which PrP(C) acts as a mediator of synaptic degeneration in Alzheimer's disease.
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Butterfield SM, Lashuel HA. Amyloidogenic protein-membrane interactions: mechanistic insight from model systems. Angew Chem Int Ed Engl 2011; 49:5628-54. [PMID: 20623810 DOI: 10.1002/anie.200906670] [Citation(s) in RCA: 474] [Impact Index Per Article: 36.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The toxicity of amyloid-forming proteins is correlated with their interactions with cell membranes. Binding events between amyloidogenic proteins and membranes result in mutually disruptive structural perturbations, which are associated with toxicity. Membrane surfaces promote the conversion of amyloid-forming proteins into toxic aggregates, and amyloidogenic proteins, in turn, compromise the structural integrity of the cell membrane. Recent studies with artificial model membranes have highlighted the striking resemblance of the mechanisms of membrane permeabilization of amyloid-forming proteins to those of pore-forming toxins and antimicrobial peptides.
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Affiliation(s)
- Sara M Butterfield
- Laboratory of Molecular Neurobiology and Neuroproteomics, Swiss Federal Institute of Technology Lausanne (EPFL), SV-BMI-LMNN AI2351, 1015 Lausanne, Switzerland
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24
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Scanlon DB, Karas JA. Synthesis of peptide sequences derived from fibril-forming proteins. Methods Mol Biol 2011; 752:29-43. [PMID: 21713629 DOI: 10.1007/978-1-60327-223-0_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The pathogenesis of a large number of diseases, including Alzheimer's Disease, Parkinson's Disease, and Creutzfeldt-Jakob Disease (CJD), is associated with protein aggregation and the formation of amyloid, fibrillar deposits. Peptide fragments of amyloid-forming proteins have been found to form fibrils in their own right and have become important tools for unlocking the mechanism of amyloid fibril formation and the pathogenesis of amyloid diseases. The synthesis and purification of peptide sequences derived from amyloid fibril-forming proteins can be extremely challenging. The synthesis may not proceed well, generating a very low quality crude product which can be difficult to purify. Even clean crude peptides can be difficult to purify, as they are often insoluble or form fibrils rapidly in solution. This chapter presents methods to recognise and to overcome the difficulties associated with the synthesis, and purification of fibril-forming peptides, illustrating the points with three synthetic examples.
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Affiliation(s)
- Denis B Scanlon
- Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia.
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25
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Abstract
The relationship between Alzheimer disease (AD) and prion-related encephalopathies (TSE) has been proposed by different points of view. Recently, the scientific attention has been attracted by the results proposing the possibility that PrPc, the protein whose pathologic form is responsible of TSE, can mediated the toxic effect of β amyloid (Aβ) oligomers. The oligomers are considered the culprit of the neurodegenerative process associated to AD, although the pathogenic mechanism activated by these small aggregates remain to be elucidated. In the initial study based on the binding screening PrPc was identified as ligand /receptor of Aβ oligomers, while long term potentiation (LTP) analysis in vitro and behavioural studies in vivo, demonstrated that the absence of PrPc abolished the damage induced by Aβ oligomers. The high affinity binding Aβ oligomers-PrPc has been confirmed, whereas a functional role of this association has been excluded by three different studies. We approached this issue by the direct application of Aβ oligomers in the brain followed by the behavioural examination of memory deficits. Our data using PrP knock-out mice suggest that Aβ 1-42 oligomers are responsible for cognitive impairment in AD but PrPc is not required for their effect. Similarly, in two other studies the LTP alterations induced by Aβ 1-42 oligomers was not influenced by the absence of PrP. Possible explanations of these contradictory results are discussed.
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Affiliation(s)
- Gianluigi Forloni
- Biology of Neurodegenerative Diseases Lab, Department of Neuroscience, Mario Negri Institute for Pharmacological Research, Milano, Italy
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26
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Butterfield S, Lashuel H. Wechselwirkungen zwischen amyloidogenen Proteinen und Membranen: Modellsysteme liefern mechanistische Einblicke. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200906670] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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27
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Amyloid peptide pores and the beta sheet conformation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2010; 677:150-67. [PMID: 20687488 DOI: 10.1007/978-1-4419-6327-7_13] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Over 20 clinical syndromes have been described as amyloid diseases. Pathologically, these illnesses are characterized by the deposition in various tissues of amorphous, Congo red stainingdeposits, referred to as amyloid. Under polarizing light microscopy, these deposits exhibit characteristic green birefringence. X-ray diffraction reveals cross-beta structure of extended amyloid fibrils. Although there is always a major protein in amyloid deposits, the predominant protein differs in each ofthe clinical syndromes. All the proteins exhibit the characteristic nonnative beta-sheet state. These proteins aggregate spontaneously into extended fibrils and precipitate out of solution. At least a dozen of these peptides have been demonstrated to be capable of channel formation in lipid bilayers and it has been proposed that this represents a pathogenic mechanism. Remarkably, the channels formed by these various peptides exhibit a number of common properties including irreversible, spontaneous insertion into membranes, production oflarge, heterogeneous single-channel conductances, relatively poor ion selectivity, inhibition of channel formation by Congo red and related dyes and blockade of inserted channels by zinc. In vivo amyloid peptides have been shown to disrupt intracellular calcium regulation, plasma membrane potential, mitochondrial membrane potential and function and long-term potentiation in neurons. Amyloid peptides also cause cytotoxicity. Formation of the beta sheet conformation from native protein structures can be induced by high protein concentrations, metal binding, acidic pH, amino acid mutation and interaction with lipid membranes. Most amyloid peptides interact strongly with membranes and this interaction is enhanced by conditions which favor beta-sheet formation. Formation of pores in these illnesses appears to be a spontaneous process and available evidence suggests several steps are critical. First, destabilization of the native structure and formation of the beta-sheet conformation must occur. This may occur in solution or may be facilitated by contact with lipid membranes. Oligomerization of the amyloid protein is then mediated by the beta strands. Amyloid monomers and extended fibrils appear to have little potential for toxicity whereas there is much evidence implicating amyloid oligomers of intermediate size in the pathogenesis of amyloid disease. Insertion of the oligomer appears to take place spontaneously although there may be a contribution of acidic pH and/or membrane potential. Very little is known about the structure of amyloid pores, but given that the amyloid peptides must acquire beta-sheet conformation to aggregate and polymerize, it has been hypothesized that amyloid pores may in fact be beta-sheet barrels similar to the pores formed by alpha-latrotoxin, Staphylococcal alpha-hemolysin, anthrax toxin and clostridial perfringolysin.
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28
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Caughey B, Baron GS, Chesebro B, Jeffrey M. Getting a grip on prions: oligomers, amyloids, and pathological membrane interactions. Annu Rev Biochem 2009; 78:177-204. [PMID: 19231987 DOI: 10.1146/annurev.biochem.78.082907.145410] [Citation(s) in RCA: 249] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The prion (infectious protein) concept has evolved with the discovery of new self-propagating protein states in organisms as diverse as mammals and fungi. The infectious agent of the mammalian transmissible spongiform encephalopathies (TSE) has long been considered the prototypical prion, and recent cell-free propagation and biophysical analyses of TSE infectivity have now firmly established its prion credentials. Other disease-associated protein aggregates, such as some amyloids, can also have prion-like characteristics under certain experimental conditions. However, most amyloids appear to lack the natural transmissibility of TSE prions. One feature that distinguishes the latter from the former is the glycophosphatidylinositol membrane anchor on prion protein, the molecule that is corrupted in TSE diseases. The presence of this anchor profoundly affects TSE pathogenesis, which involves major membrane distortions in the brain, and may be a key reason for the greater neurovirulence of TSE prions relative to many other autocatalytic protein aggregates.
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Affiliation(s)
- Byron Caughey
- Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute for Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT 59840, USA.
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29
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Keblesh JP, Dou H, Gendelman HE, Xiong H. 4-Aminopyridine improves spatial memory in a murine model of HIV-1 encephalitis. J Neuroimmune Pharmacol 2009; 4:317-27. [PMID: 19462247 DOI: 10.1007/s11481-009-9161-7] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 05/08/2009] [Indexed: 11/24/2022]
Abstract
HIV-1-associated neurocognitive disorders (HAND) remains a significant source of morbidity in the era of wide spread use of highly active antiretroviral therapy. Disease is precipitated by low levels of viral growth and glial immune activation within the central nervous system. Blood borne macrophage and microglia affect a proinflammatory response and release viral proteins that affects neuronal viability and leads to death of nerve cells. Increasing evidence supports the notion that HAND is functional channelopathy, but proof of this concept remains incomplete. Based on their role in learning and memory processes, we now posit that voltage-gated potassium (K(v)) channels could be a functional substrate for disease. This was tested in the severe combined immunodeficient (SCID) mouse model of HIV-1 encephalitis (HIVE) by examining whether the K(v) channel blocker, 4-aminopyridine (4-AP), could affect behavioral, electrophysiological, and morphological measures of learning and memory. HIVE SCID mice showed impaired spatial memory in radial arm water maze tests. Electrophysiology studies revealed a reduction of long-term potentiation (LTP) in the CA1 region of the hippocampus. Importantly, systemic administration of 4-AP blocked HIV-1-associated reduction of LTP and improved animal performance in the radial arm water maze. These results support the importance of K(v) channel dysfunction in disease but, more importantly, provide a potential target for adjunctive therapies for HAND.
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Affiliation(s)
- James P Keblesh
- Neurophysiology Laboratory, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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30
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Monocyte chemotactic protein-1 regulates voltage-gated K+ channels and macrophage transmigration. J Neuroimmune Pharmacol 2008; 4:47-59. [PMID: 19034671 DOI: 10.1007/s11481-008-9135-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2008] [Accepted: 10/31/2008] [Indexed: 10/21/2022]
Abstract
Progressive human immunodeficiency virus (HIV)-1 infection and virus-induced neuroinflammatory responses effectuate monocyte-macrophage transmigration across the blood-brain barrier (BBB). A key factor in mediating these events is monocyte chemotactic protein-1 (MCP-1). Upregulated glial-derived MCP-1 in HIV-1-infected brain tissues generates a gradient for monocyte recruitment into the nervous system. We posit that the inter-relationships between MCP-1, voltage-gated ion channels, cell shape and volume, and cell mobility underlie monocyte transmigration across the BBB. In this regard, MCP-1 serves both as a chemoattractant and an inducer of monocyte-macrophage ion flux affecting cell shape and mobility. To address this hypothesis, MCP-1-treated bone marrow-derived macrophages (BMM) were analyzed for gene and protein expression, electrophysiology, and capacity to migrate across a laboratory constructed BBB. MCP-1 enhanced K+ channel gene (KCNA3) and channel protein expression. Electrophysiological studies revealed that MCP-1 increased outward K+ currents in a dose-dependent manner. In vitro studies demonstrated that MCP-1 increased BMM migration across an artificial BBB, and the MCP-1-induced BMM migration was blocked by tetraethylammonium, a voltage-gated K+ channel blocker. Together these data demonstrated that MCP-1 affects macrophage migratory movement through regulation of voltage-gated K+ channels and, as such, provides a novel therapeutic strategy for neuroAIDS.
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31
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Natalello A, Prokorov VV, Tagliavini F, Morbin M, Forloni G, Beeg M, Manzoni C, Colombo L, Gobbi M, Salmona M, Doglia SM. Conformational Plasticity of the Gerstmann–Sträussler–Scheinker Disease Peptide as Indicated by Its Multiple Aggregation Pathways. J Mol Biol 2008; 381:1349-61. [DOI: 10.1016/j.jmb.2008.06.063] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2008] [Revised: 06/17/2008] [Accepted: 06/21/2008] [Indexed: 10/21/2022]
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32
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Simoneau S, Rezaei H, Salès N, Kaiser-Schulz G, Lefebvre-Roque M, Vidal C, Fournier JG, Comte J, Wopfner F, Grosclaude J, Schätzl H, Lasmézas CI. In vitro and in vivo neurotoxicity of prion protein oligomers. PLoS Pathog 2007; 3:e125. [PMID: 17784787 PMCID: PMC1959381 DOI: 10.1371/journal.ppat.0030125] [Citation(s) in RCA: 184] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2007] [Accepted: 07/10/2007] [Indexed: 11/18/2022] Open
Abstract
The mechanisms underlying prion-linked neurodegeneration remain to be elucidated, despite several recent advances in this field. Herein, we show that soluble, low molecular weight oligomers of the full-length prion protein (PrP), which possess characteristics of PrP to PrPsc conversion intermediates such as partial protease resistance, are neurotoxic in vitro on primary cultures of neurons and in vivo after subcortical stereotaxic injection. Monomeric PrP was not toxic. Insoluble, fibrillar forms of PrP exhibited no toxicity in vitro and were less toxic than their oligomeric counterparts in vivo. The toxicity was independent of PrP expression in the neurons both in vitro and in vivo for the PrP oligomers and in vivo for the PrP fibrils. Rescue experiments with antibodies showed that the exposure of the hydrophobic stretch of PrP at the oligomeric surface was necessary for toxicity. This study identifies toxic PrP species in vivo. It shows that PrP-induced neurodegeneration shares common mechanisms with other brain amyloidoses like Alzheimer disease and opens new avenues for neuroprotective intervention strategies of prion diseases targeting PrP oligomers.
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Affiliation(s)
- Steve Simoneau
- Commissariat à l'Energie Atomique, Fontenay-aux-Roses, France
| | - Human Rezaei
- Institut National de la Recherche Agronomique, Jouy-en-Josas, France
| | - Nicole Salès
- Department of Infectology, The Scripps Research Institute, Jupiter, Florida, United States of America
| | | | - Maxime Lefebvre-Roque
- Commissariat à l'Energie Atomique, Fontenay-aux-Roses, France
- Department of Infectology, The Scripps Research Institute, Jupiter, Florida, United States of America
| | | | | | - Julien Comte
- Commissariat à l'Energie Atomique, Fontenay-aux-Roses, France
| | - Franziska Wopfner
- Institute of Virology, Technical University of Munich, Munich, Germany
| | - Jeanne Grosclaude
- Institut National de la Recherche Agronomique, Jouy-en-Josas, France
| | - Hermann Schätzl
- Institute of Virology, Technical University of Munich, Munich, Germany
| | - Corinne Ida Lasmézas
- Department of Infectology, The Scripps Research Institute, Jupiter, Florida, United States of America
- * To whom correspondence should be addressed. E-mail:
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33
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Irvine E, Keblesh J, Liu J, Xiong H. Voltage-gated potassium channel modulation of neurotoxic activity in human immunodeficiency virus type-1(HIV-1)-infected macrophages. J Neuroimmune Pharmacol 2007; 2:265-9. [PMID: 18040860 DOI: 10.1007/s11481-007-9072-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Accepted: 03/15/2007] [Indexed: 11/30/2022]
Abstract
Macrophages play an important role in brain immune and inflammatory responses. They are also critical cells in mediating the pathology of neurodegenerative disorders such as HIV-associated dementia. This is largely through their capacity to secrete a variety of bioactive molecules such as cytokines, leading to neuronal dysfunction and/or death. Accumulating evidence indicates that voltage-gated potassium (Kv) channels play a pivotal role in the modulation of macrophage proliferation, activation, and secretion. Blockade of Kv channels by specific antagonists decreases macrophage cytokine production and ameliorates macrophage-associated neuronal injury. These results suggest that Kv channels might become a potential target for the development of new therapeutic strategies for chronic inflammatory diseases.
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Affiliation(s)
- Elizabeth Irvine
- Neurophysiology Laboratory, the Center for Neurovirology and Neurodegenerative Disorders, and Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE 68198-5880, USA
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34
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Fioriti L, Angeretti N, Colombo L, De Luigi A, Colombo A, Manzoni C, Morbin M, Tagliavini F, Salmona M, Chiesa R, Forloni G. Neurotoxic and gliotrophic activity of a synthetic peptide homologous to Gerstmann-Sträussler-Scheinker disease amyloid protein. J Neurosci 2007; 27:1576-83. [PMID: 17301166 PMCID: PMC6673725 DOI: 10.1523/jneurosci.5145-06.2007] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Amyloid fibrils in Gerstmann-Sträussler-Scheinker (GSS) disease are composed of a fragment of the prion protein (PrP), the N and C termini of which correspond to ragged residues 81-90 and 144-153. A synthetic peptide spanning the sequence 82-146 (PrP 82-146) polymerizes into protease-resistant fibrils with the tinctorial properties of amyloid. We investigated the biological activity of PrP 82-146 and of two nonamyloidogenic variants of PrP 82-146 with scrambled amino acid sequence 106-126 or 127-146. Cortical neurons prepared from rat and mouse embryos were chronically exposed to the PrP 82-146 peptides (10-50 microM). PrP 82-146 and the partially scrambled peptides induced neuronal death with a similar dose-response pattern, indicating that neurotoxicity was independent of amyloid fibril formation. Neurotoxicity was significantly reduced by coadministration of an anti-oligomer antibody, suggesting that PrP 82-146 oligomers are primarily responsible for triggering cell death. Neurons from PrP knock-out (Prnp0/0) mice were significantly less sensitive to PrP 82-146 toxicity than neurons expressing PrP. The gliotrophic effect of PrP 82-146 was determined by [methyl-3H]-thymidine incorporation in cultured astrocytes. Treatment with PrP 82-146 stimulated [methyl-3H]-thymidine uptake 3.5-fold. This activity was significantly less when the 106-126 or 127-146 regions were disrupted, indicating that PrP 82-146 amyloid activates the gliotrophic response. Prnp0/0 astrocytes were insensitive to the proliferative stimulus of PrP 82-146. These results underline the role of cerebral accumulation of abnormally folded PrP fragments and indicate that cellular PrP governs the pathogenic process.
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Affiliation(s)
- Luana Fioriti
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
- Dulbecco Telethon Institute, 20157 Milano, Italy, and
| | - Nadia Angeretti
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Laura Colombo
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Ada De Luigi
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Alessio Colombo
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Claudia Manzoni
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Michela Morbin
- Istituto Neurologico Nazionale “Carlo Besta,” 20133 Milano, Italy
| | | | - Mario Salmona
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
| | - Roberto Chiesa
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
- Dulbecco Telethon Institute, 20157 Milano, Italy, and
| | - Gianluigi Forloni
- Istituto di Ricerche Farmacologiche “Mario Negri,” 20157 Milano, Italy
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Stock C, Schilling T, Schwab A, Eder C. Lysophosphatidylcholine stimulates IL-1beta release from microglia via a P2X7 receptor-independent mechanism. THE JOURNAL OF IMMUNOLOGY 2007; 177:8560-8. [PMID: 17142754 DOI: 10.4049/jimmunol.177.12.8560] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
IL-1beta released from activated macrophages contributes significantly to tissue damage in inflammatory, degenerative, and autoimmune diseases. In the present study, we identified a novel mechanism of IL-1beta release from activated microglia (brain macrophages) that occurred independently of P2X(7) ATP receptor activation. Stimulation of LPS-preactivated microglia with lysophosphatidylcholine (LPC) caused rapid processing and secretion of mature 17-kDa IL-1beta. Neither LPC-induced IL-1beta release nor LPC-stimulated intracellular Ca(2+) increases were affected by inhibition of P2X(7) ATP receptors with oxidized ATP. Microglial LPC-induced IL-1beta release was suppressed in Ca(2+)-free medium or during inhibition of nonselective cation channels with Gd(3+) or La(3+). It was also attenuated when Ca(2+)-activated K(+) channels were blocked with charybdotoxin (CTX). The electroneutral K(+) ionophore nigericin did not reverse the suppressive effects of CTX on LPC-stimulated IL-1beta release, demonstrating the importance of membrane hyperpolarization. Furthermore, LPC-stimulated caspase activity was unaffected by Ca(2+)-free medium or CTX, suggesting that secretion but not processing of IL-1beta is Ca(2+)- and voltage-dependent. In summary, these data indicate that the activity of nonselective cation channels and Ca(2+)-activated K(+) channels is required for optimal IL-1beta release from LPC-stimulated microglia.
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Affiliation(s)
- Christian Stock
- Institute of Physiology II, University of Muenster, Muenster, Germany
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Uversky VN, Kabanov AV, Lyubchenko YL. Nanotools for megaproblems: probing protein misfolding diseases using nanomedicine modus operandi. J Proteome Res 2006; 5:2505-22. [PMID: 17022621 PMCID: PMC1880889 DOI: 10.1021/pr0603349] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Misfolding and self-assembly of proteins in nanoaggregates of different sizes and morphologies (nanoensembles, primary nanofilaments, nanorings, filaments, protofibrils, fibrils, etc.) is a common theme unifying a number of human pathologies termed protein misfolding diseases. Recent studies highlight increasing recognition of the public health importance of protein misfolding diseases, including various neurodegenerative disorders and amyloidoses. It is understood now that the first essential elements in the vast majority of neurodegenerative processes are misfolded and aggregated proteins. Altogether, the accumulation of abnormal protein nanoensembles exerts toxicity by disrupting intracellular transport, overwhelming protein degradation pathways, and/or disturbing vital cell functions. In addition, the formation of inclusion bodies is known to represent a major problem in the production of recombinant therapeutic proteins. Formulation of these therapeutic proteins into delivery systems and their in vivo delivery are often complicated by protein association. Thus, protein folding abnormalities and subsequent events underlie a multitude of human pathologies and difficulties with protein therapeutic applications. The field of medicine therefore can be greatly advanced by establishing a fundamental understanding of key factors leading to misfolding and self-assembly responsible for various protein folding pathologies. This article overviews protein misfolding diseases and outlines some novel and advanced nanotechnologies, including nanoimaging techniques, nanotoolboxes and nanocontainers, complemented by appropriate ensemble techniques, all focused on the ultimate goal to establish etiology and to diagnose, prevent, and cure these devastating disorders.
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Affiliation(s)
- Vladimir N Uversky
- Center for Computational Biology and Bioinformatics, Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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Pelegrin P, Surprenant A. Pannexin-1 mediates large pore formation and interleukin-1beta release by the ATP-gated P2X7 receptor. EMBO J 2006; 25:5071-82. [PMID: 17036048 PMCID: PMC1630421 DOI: 10.1038/sj.emboj.7601378] [Citation(s) in RCA: 1139] [Impact Index Per Article: 63.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2006] [Accepted: 09/08/2006] [Indexed: 12/24/2022] Open
Abstract
P2X(7) receptors are ATP-gated cation channels; their activation in macrophage also leads to rapid opening of a membrane pore permeable to dyes such as ethidium, and to release of the pro-inflammatory cytokine, interleukin-1beta (IL-1beta). It has not been known what this dye-uptake path is, or whether it is involved in downstream signalling to IL-1beta release. Here, we identify pannexin-1, a recently described mammalian protein that functions as a hemichannel when ectopically expressed, as this dye-uptake pathway and show that signalling through pannexin-1 is required for processing of caspase-1 and release of mature IL-1beta induced by P2X(7) receptor activation.
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Affiliation(s)
- Pablo Pelegrin
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
| | - Annmarie Surprenant
- Department of Biomedical Science, University of Sheffield, Sheffield, UK
- Department of Biomedical Science, University of Sheffield, Western Bank, Sheffield, South Yorkshire S10 2TN, UK. Tel.: +44 114 222 2366; Fax: +44 114 222 2360; E-mail:
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Teisseyre A, Michalak K. Genistein inhibits the activity of kv1.3 potassium channels in human T lymphocytes. J Membr Biol 2006; 205:71-9. [PMID: 16283587 DOI: 10.1007/s00232-005-0764-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2005] [Revised: 06/21/2005] [Indexed: 10/25/2022]
Abstract
In the present study, the whole-cell patch-clamp technique was applied to follow the inhibitory effect of genistein--a tyrosine kinase inhibitor and a natural anticancer agent--on the activity of voltage-gated potassium channels Kv1.3 expressed in human T lymphocytes (TL). Obtained data provide evidence that genistein application in the concentration range of 1-80 microM reversibly decreased the whole-cell potassium currents in TL in a concentration-dependent manner to about 0.23 of the control value. The half-blocking concentration range of genistein was from 10 to 40 microM. The current inhibition was correlated in time with a significant decrease of the current activation rate. The steady-state activation of the currents was unchanged upon application of genistein, as was the inactivation rate. The inhibitory effect of genistein on the current amplitude and activation kinetics was voltage-independent. The current inhibition was not changed significantly in the presence of 1 mM of sodium orthovanadate, a tyrosine phosphatase inhibitor. Application of daidzein, an inactive genistein analogue, did not affect significantly either the current amplitudes or the activation kinetics. Possible mechanisms of the observed phenomena and their significance for genistein-induced inhibition of cancer cell proliferation are discussed.
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Affiliation(s)
- A Teisseyre
- Department of Biophysics, Wrocław Medical University, ul. Chałubińskiego 10, Wrocław, Poland.
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Abstract
Protein aggregation--and, more specifically, amyloid fibril formation--has been implicated as a primary cause of neurodegeneration in Alzheimer's disease, Parkinson's disease, and related disorders, but the mechanism by which this process triggers neuronal death is unknown. Mounting evidence from in vitro studies, cell culture, and animal models of these diseases supports the hypothesis that a structural intermediate on the pathway to fibril formation, rather than amyloid fibrils themselves, may be the pathogenic species. Characterization of these intermediates in solution or upon interactions with membranes indicate that these intermediates form pores and suggests that neurons could be killed by unregulated membrane permeabilization caused by such "amyloid pores."
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Affiliation(s)
- Hilal A Lashuel
- Integrative Biosciences Institute, Laboratory of Molecular Neurobiology and Neuroproteomics, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
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40
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Balestrini JL, Tsuchida D, Fukuda H, Pappas TN, Takahashi T. Acupuncture accelerates delayed gastrointestinal transit after abdominal surgery in conscious rats. Scand J Gastroenterol 2005; 40:734-5. [PMID: 16036535 DOI: 10.1080/00365520510015719] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- Jose L Balestrini
- Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA
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Kagan BL, Azimov R, Azimova R. Amyloid peptide channels. J Membr Biol 2005; 202:1-10. [PMID: 15702375 DOI: 10.1007/s00232-004-0709-4] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2004] [Revised: 07/28/2004] [Indexed: 12/20/2022]
Abstract
At least 16 distinct clinical syndromes including Alzheimer's disease (AD), Parkinson's disease (PD), rheumatoid arthritis, type II diabetes mellitus (DM), and spongiform encephelopathies (prion diseases), are characterized by the deposition of amorphous, Congo red-staining deposits known as amyloid. These "misfolded" proteins adopt beta-sheet structures and aggregate spontaneously into similar extended fibrils despite their widely divergent primary sequences. Many, if not all, of these peptides are capable of forming ion-permeable channels in vitro and possibly in vivo. Common channel properties include irreversible, spontaneous insertion into membranes, relatively large, heterogeneous single-channel conductances, inhibition of channel formation by Congo red, and blockade of inserted channels by Zn2+. Physiologic effects of amyloid, including Ca2+ dysregulation, membrane depolarization, mitochondrial dysfunction, inhibition of long-term potentiation (LTP), and cytotoxicity, suggest that channel formation in plasma and intracellular membranes may play a key role in the pathophysiology of the amyloidoses.
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Affiliation(s)
- B L Kagan
- Department of Psychiatry, Neuropsychiatric Institute, David Geffen School of Medicine, UCLA, Los Angeles, California 90024-1759, USA.
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Farrelly PV, Kenna BL, Laohachai KL, Bahadi R, Salmona M, Forloni G, Kourie JI. Quinacrine blocks PrP (106-126)-formed channels. J Neurosci Res 2004; 74:934-41. [PMID: 14648599 DOI: 10.1002/jnr.10849] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We investigated the action of the acridine derivative, quinacrine (QC), which has been shown to act as a noncompetitive channel inhibitor. The main effects of QC are voltage- and concentration-dependent changes in the kinetics of the prion protein fragment (PrP[106-126])-formed cation channels. The current-voltage relationships show that the maximal current (I) was not affected whereas the physiologically important mean current (I') was reduced as a result of changes in channel kinetics. These findings suggest that QC acts on the open state of the channels. The half-inhibitory concentration (IC50) for the dose-dependent effects of [QC]cis on the kinetic parameters of the PrP(106-126)-formed cation channel shows a reduction in the ratios Po(QC)/Po, Fo(QC)/Fo, and To(QC)/To, whereas Tc(QC)/Tc increases. Of these ratios, Po(QC)/Po was more sensitive than the others. The corresponding IC50 for these ratios were 51, 94, 86, and 250 microM QC, respectively. The QC-induced changes in the kinetic parameters were more apparent at positive voltages. IC50 values for Po were 95, 75, and 51 microM at +20, +80, and +140 mV, respectively. The fact that QC induced changes in the kinetics of this channel, although the conductance of the channel remained unchanged, indicates that QC may bind at the mouth of the channel via a mechanism known as fast channel block. The QC-induced changes in the kinetic parameters of this channel suggest that they are pathophysiologically significant because these channels could be the mechanisms by which amyloids induce membrane damage in vivo.
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Affiliation(s)
- Peter V Farrelly
- Membrane Transport Group, Department of Chemistry, The Faculties, The Australian National University, Canberra City, Australian Capital Territory, Australia
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