551
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Do TD, de Almeida NEC, LaPointe NE, Chamas A, Feinstein SC, Bowers MT. Amino Acid Metaclusters: Implications of Growth Trends on Peptide Self-Assembly and Structure. Anal Chem 2015; 88:868-76. [PMID: 26632663 DOI: 10.1021/acs.analchem.5b03454] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ion-mobility mass spectrometry is utilized to examine the metacluster formation of serine, asparagine, isoleucine, and tryptophan. These amino acids are representative of different classes of noncharged amino acids. We show that they can form relatively large metaclusters in solution that are difficult or impossible to observe by traditional solution techniques. We further demonstrate, as an example, that the formation of Ser metaclusters is not an ESI artifact because large metaclusters can be detected in negative polarity and low concentration with similar cross sections to those measured in positive polarity and higher concentration. The growth trends of tryptophan and isoleucine metaclusters, along with serine, asparagine, and the previously studied phenylalanine, are balanced among various intrinsic properties of individual amino acids (e.g., hydrophobicity, size, and shape). The metacluster cross sections of hydrophilic residues (Ser, Asn, Trp) tend to stay on or fall below the isotropic model trend lines whereas those of hydrophobic amino acids (Ile, Phe) deviate positively from the isotropic trend lines. The growth trends correlate well to the predicted aggregation propensity of individual amino acids. From the metacluster data, we introduce a novel approach to score and predict aggregation propensity of peptides, which can offer a significant improvement over the existing methods in terms of accuracy. Using a set of hexapeptides, we show that the strong negative deviations of Ser metaclusters from the isotropic model leads a prediction of microcrystalline formation for the SFSFSF peptide, whereas the strong positive deviation of Ile leads to prediction or fibril formation for the NININI peptide. Both predictions are confirmed experimentally using ion mobility and TEM measurements. The peptide SISISI is predicted to only weakly aggregate, a prediction confirmed by TEM.
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Affiliation(s)
- Thanh D Do
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
| | - Natália E C de Almeida
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
| | - Nichole E LaPointe
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
| | - Ali Chamas
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
| | - Stuart C Feinstein
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
| | - Michael T Bowers
- Department of Chemistry and Biochemistry and ‡Neuroscience Research Institute and Department of Molecular Cellular and Developmental Biology University of California , Santa Barbara, California 93106, United States
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552
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Dutta C, Yang M, Long F, Shahbazian-Yassar R, Tiwari A. Preformed Seeds Modulate Native Insulin Aggregation Kinetics. J Phys Chem B 2015; 119:15089-99. [DOI: 10.1021/acs.jpcb.5b07221] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Colina Dutta
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Mu Yang
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Fei Long
- Department
of Mechanical Engineering, Michigan Technological University, Houghton, Michigan 49931, United States
| | - Reza Shahbazian-Yassar
- Department
of Mechanical Engineering, Michigan Technological University, Houghton, Michigan 49931, United States
- Department
of Mechanical and Industrial Engineering, University of Illinois at Chicago, Chicago, Illinois 60607, United States
| | - Ashutosh Tiwari
- Department
of Chemistry, Michigan Technological University, Houghton, Michigan 49931, United States
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553
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Akter R, Cao P, Noor H, Ridgway Z, Tu LH, Wang H, Wong AG, Zhang X, Abedini A, Schmidt AM, Raleigh DP. Islet Amyloid Polypeptide: Structure, Function, and Pathophysiology. J Diabetes Res 2015; 2016:2798269. [PMID: 26649319 PMCID: PMC4662979 DOI: 10.1155/2016/2798269] [Citation(s) in RCA: 156] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Accepted: 04/24/2015] [Indexed: 01/29/2023] Open
Abstract
The hormone islet amyloid polypeptide (IAPP, or amylin) plays a role in glucose homeostasis but aggregates to form islet amyloid in type-2 diabetes. Islet amyloid formation contributes to β-cell dysfunction and death in the disease and to the failure of islet transplants. Recent work suggests a role for IAPP aggregation in cardiovascular complications of type-2 diabetes and hints at a possible role in type-1 diabetes. The mechanisms of IAPP amyloid formation in vivo or in vitro are not understood and the mechanisms of IAPP induced β-cell death are not fully defined. Activation of the inflammasome, defects in autophagy, ER stress, generation of reactive oxygen species, membrane disruption, and receptor mediated mechanisms have all been proposed to play a role. Open questions in the field include the relative importance of the various mechanisms of β-cell death, the relevance of reductionist biophysical studies to the situation in vivo, the molecular mechanism of amyloid formation in vitro and in vivo, the factors which trigger amyloid formation in type-2 diabetes, the potential role of IAPP in type-1 diabetes, the development of clinically relevant inhibitors of islet amyloidosis toxicity, and the design of soluble, bioactive variants of IAPP for use as adjuncts to insulin therapy.
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Affiliation(s)
- Rehana Akter
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ping Cao
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Harris Noor
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Zachary Ridgway
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Hui Wang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Amy G. Wong
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Xiaoxue Zhang
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
| | - Andisheh Abedini
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Ann Marie Schmidt
- Diabetes Research Program, NYU School of Medicine, 550 First Avenue, New York, NY 10016, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, NY 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London WC1E 6BT, UK
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554
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Abstract
Diabetes, a group of metabolic and age-related diseases, is a major global health problem, the incidence of which has increased dramatically in recent decades. Type 1 diabetes mellitus (T1DM) is a complex, T cell-mediated autoimmune disease characterized by immune cell infiltration and chronic inflammation in the islets of Langerhans. Type 2 diabetes mellitus (T2DM) is a complex metabolic disease characterized by hyperglycemia (high blood sugar) resulting from insulin resistance and β-cell dysfunction. The involvement of inflammatory processes, such as immune cell infiltration, and chronic inflammation in the pathogenesis of diabetes is less well understood in T2DM than in T1DM. However, studies conducted in the past decade have shown a strong link between inflammation and metabolic dysfunction. They have also shown that chronic inflammation plays a key role in the pathogenesis of both T1DM and T2DM. Two immunological factors commonly contribute to the pathogenesis of diabetes: the activation of inflammasomes and the release of proinflammatory cytokines in response to damage-associated molecular patterns (DAMPs). Inflammasomes are intracellular multiprotein molecular platforms. DAMPs act as endogenous danger signals. Here, we review current research on the function(s) of inflammasomes and DAMPs and discuss their pathological relevance and therapeutic implications in diabetes.
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555
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Effects of gold complexes on the assembly behavior of human islet amyloid polypeptide. J Inorg Biochem 2015; 152:114-22. [DOI: 10.1016/j.jinorgbio.2015.08.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Revised: 08/09/2015] [Accepted: 08/20/2015] [Indexed: 11/24/2022]
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556
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Ly H, Despa F. Hyperamylinemia as a risk factor for accelerated cognitive decline in diabetes. Expert Rev Proteomics 2015; 12:575-7. [PMID: 26503000 DOI: 10.1586/14789450.2015.1104251] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Type II diabetes increases the risk for cognitive decline via multiple traits. Amylin is a pancreatic hormone that has amyloidogenic and cytotoxic properties similar to the amyloid-β peptide. The amylin hormone is overexpressed in individuals with pre-diabetic insulin resistance or obesity leading to amylin oligomerization and deposition in pancreatic islets. Amylin oligomerization was implicated in the apoptosis of the insulin-producing β-cells. Recent studies showed that brain tissue from diabetic patients with cerebrovascular dementia or Alzheimer's disease contains significant deposits of oligomerized amylin. It has also been reported that the brain amylin deposition reduced exploratory drive, recognition memory and vestibulomotor function in a rat model that overexpresses human amylin in the pancreas. These novel findings are reviewed here and the hypothesis that type II diabetes is linked with cognitive decline by amylin accumulation in the brain is proposed. Deciphering the impact of hyperamylinemia on the brain is critical for both etiology and treatment of dementia.
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Affiliation(s)
- Han Ly
- a Department of Pharmacology and Nutritional Sciences , University of Kentucky, College of Medicine , Lexington , KY 40536 , USA
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557
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Young LM, Mahood RA, Saunders JC, Tu LH, Raleigh DP, Radford SE, Ashcroft AE. Insights into the consequences of co-polymerisation in the early stages of IAPP and Aβ peptide assembly from mass spectrometry. Analyst 2015; 140:6990-9. [PMID: 26193839 PMCID: PMC4626081 DOI: 10.1039/c5an00865d] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The precise molecular mechanisms by which different peptides and proteins assemble into highly ordered amyloid deposits remain elusive. The fibrillation of human amylin (also known as islet amyloid polypeptide, hIAPP) and the amyloid-beta peptide (Aβ-40) are thought to be pathogenic factors in Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD), respectively. Amyloid diseases may involve co-aggregation of different protein species, in addition to the self-assembly of single precursor sequences. Here we investigate the formation of heterogeneous pre-fibrillar, oligomeric species produced by the co-incubation of hIAPP and Aβ-40 using electrospray ionisation-ion mobility spectrometry-mass spectrometry (ESI-IMS-MS)-based methods. Conformational properties and gas-phase stabilities of amyloid oligomers formed from hIAPP or Aβ40 alone, and from a 1 : 1 mixture of hIAPP and Aβ40 monomers, were determined and compared. We show that co-assembly of the two sequences results in hetero-oligomers with distinct properties and aggregation kinetics properties compared with the homo-oligomers present in solution. The observations may be of key significance to unravelling the mechanisms of amyloid formation in vivo and elucidating how different sequences and/or assembly conditions can result in different fibril structures and/or pathogenic outcomes.
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Affiliation(s)
- Lydia M. Young
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Rachel A. Mahood
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Janet C. Saunders
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Ling-Hsien Tu
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
| | - Daniel P. Raleigh
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, USA
- Research Department of Structural and Molecule Biology, University College London, Gower Street, London, WC1E 6BT, UK
| | - Sheena E. Radford
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
| | - Alison E. Ashcroft
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, University of Leeds, LS2 9JT, UK
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558
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De Carufel CA, Quittot N, Nguyen PT, Bourgault S. Delineating the Role of Helical Intermediates in Natively Unfolded Polypeptide Amyloid Assembly and Cytotoxicity. Angew Chem Int Ed Engl 2015; 54:14383-7. [DOI: 10.1002/anie.201507092] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 09/04/2015] [Indexed: 11/10/2022]
Affiliation(s)
- Carole Anne De Carufel
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Noé Quittot
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Phuong Trang Nguyen
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
| | - Steve Bourgault
- Department of Chemistry, Université du Québec à Montréal, Quebec Network for Research on Protein Function, Structure and Engineering (PROTEO), C.P. 8888, Montréal (Canada)
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559
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De Carufel CA, Quittot N, Nguyen PT, Bourgault S. Delineating the Role of Helical Intermediates in Natively Unfolded Polypeptide Amyloid Assembly and Cytotoxicity. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201507092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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560
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Arrojo e Drigo R, Ali Y, Diez J, Srinivasan DK, Berggren PO, Boehm BO. New insights into the architecture of the islet of Langerhans: a focused cross-species assessment. Diabetologia 2015. [PMID: 26215305 DOI: 10.1007/s00125-015-3699-0] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The human genome project and its search for factors underlying human diseases has fostered a major human research effort. Therefore, unsurprisingly, in recent years we have observed an increasing number of studies on human islet cells, including disease approaches focusing on type 1 and type 2 diabetes. Yet, the field of islet and diabetes research relies on the legacy of rodent-based investigations, which have proven difficult to translate to humans, particularly in type 1 diabetes. Whole islet physiology and pathology may differ between rodents and humans, and thus a comprehensive cross-species as well as species-specific view on islet research is much needed. In this review we summarise the current knowledge of interspecies islet cytoarchitecture, and discuss its potential impact on islet function and future perspectives in islet pathophysiology research.
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Affiliation(s)
- Rafael Arrojo e Drigo
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Yusuf Ali
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Juan Diez
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Dinesh Kumar Srinivasan
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore
| | - Per-Olof Berggren
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore.
- Imperial College London, London, UK.
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska University Hospital L1, Karolinska Institutet, SE-171 76, Stockholm, Sweden.
| | - Bernhard O Boehm
- Lee Kong Chian School of Medicine, Nanyang Technological University, 50 Nanyang Drive, Research Techno Plaza, Level 4, 637 553, Singapore, Singapore.
- Imperial College London, London, UK.
- Department of Internal Medicine 1, Ulm University Medical Centre, Ulm, Germany.
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561
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Fortin JS, Benoit-Biancamano MO. In Vitro Evaluation of Hypoglycemic Agents to Target Human Islet Amyloid Polypeptide: A Key Protein Involved in Amyloid Deposition and Beta-Cell Loss. Can J Diabetes 2015; 39:373-82. [DOI: 10.1016/j.jcjd.2015.01.291] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 01/09/2015] [Accepted: 01/28/2015] [Indexed: 11/26/2022]
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562
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Hieronymus L, Griffin S. Role of Amylin in Type 1 and Type 2 Diabetes. DIABETES EDUCATOR 2015; 41:47S-56S. [DOI: 10.1177/0145721715607642] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Purpose The pathophysiology of diabetes has historically focused on alterations in insulin secretion and function; however, diabetes involves multiple hormonal alterations, including abnormal regulation of amylin. This review discusses the physiologic functions of amylin in glucose homeostasis and the rationale for amylin replacement in type 1 and 2 diabetes. The use of pramlintide, a synthetic amylin analog, is also discussed. Conclusions Amylin, formed primarily in pancreatic islet β cells, is cosecreted with insulin in response to caloric intake. Patients with type 1 diabetes have lower baseline amylin serum concentrations, and amylin response to caloric intake is absent. Patients with type 2 diabetes requiring insulin also have a diminished amylin response to caloric intake, potentially related to the degree of β-cell impairment. Key physiologic functions of amylin in maintaining glucose homeostasis include suppressing glucagon release in response to caloric intake, delaying the rate of gastric emptying, and stimulating the satiety center in the brain to limit caloric intake. Pramlintide is indicated for adults with type 1 and 2 diabetes who have not achieved adequate glucose control despite optimal insulin therapy. As an adjunct to insulin therapy, pramlintide demonstrated significant reductions in A1C in patients with type 1 and 2 diabetes, with favorable effects on body weight. It is administered subcutaneously before each major meal. There is an increased risk of hypoglycemia with insulin when used in combination with pramlintide. Other adverse effects may include nausea, vomiting, anorexia, reduced appetite, and headache. Proper patient selection and education are essential to successful pramlintide use.
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Affiliation(s)
- Laura Hieronymus
- DiabetesCare & Communications, Lexington, KY, USA (Dr Hieronymus)
- Baptist Health-Lexington, KY, USA (Dr Griffin)
| | - Stacy Griffin
- DiabetesCare & Communications, Lexington, KY, USA (Dr Hieronymus)
- Baptist Health-Lexington, KY, USA (Dr Griffin)
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563
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Accardo A, Shalabaeva V, Di Cola E, Burghammer M, Krahne R, Riekel C, Dante S. Superhydrophobic Surfaces Boost Fibril Self-Assembly of Amyloid β Peptides. ACS APPLIED MATERIALS & INTERFACES 2015; 7:20875-20884. [PMID: 26306595 DOI: 10.1021/acsami.5b06219] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Amyloid β (Aβ) peptides are the main constituents of Alzheimer's amyloid plaques in the brain. Here we report how the unique microfluidic flows exerted by droplets sitting on superhydrophobic surfaces can influence the aggregation mechanisms of several Aβ fragments by boosting their fibril self-assembly. Aβ(25-35), Aβ(1-40), and Aβ(12-28) were dried both on flat hydrophilic surfaces (contact angle (CA) = 37.3°) and on nanostructured superhydrophobic ones (CA = 175.8°). By embedding nanoroughened surfaces on top of highly X-ray transparent Si3N4 membranes, it was possible to probe the solid residues by raster-scan synchrotron radiation X-ray microdiffraction (μXRD). As compared to residues obtained on flat Si3N4 membranes, a general enhancement of fibrillar material was detected for all Aβ fragments dried on superhydrophobic surfaces, with a particular emphasis on the shorter ones. Indeed, both Aβ(25-35) and Aβ(12-28) showed a marked crystalline cross-β phase with varying fiber textures. The homogeneous evaporation rate provided by these nanostructured supports, and the possibility to use transparent membranes, can open a wide range of in situ X-ray and spectroscopic characterizations of amyloidal peptides involved in neurodegenerative diseases and for the fabrication of amyloid-based nanodevices.
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Affiliation(s)
- Angelo Accardo
- Istituto Italiano di Tecnologia , Via Morego 30, Genova 16163, Italy
| | | | - Emanuela Di Cola
- The European Synchrotron, CS40220 , 38043 Cedex 9 Grenoble, France
| | - Manfred Burghammer
- The European Synchrotron, CS40220 , 38043 Cedex 9 Grenoble, France
- Department of Analytical Chemistry, Ghent University , Krijgslaan 281, Ghent 9000, Belgium
| | - Roman Krahne
- Istituto Italiano di Tecnologia , Via Morego 30, Genova 16163, Italy
| | - Christian Riekel
- The European Synchrotron, CS40220 , 38043 Cedex 9 Grenoble, France
| | - Silvia Dante
- Istituto Italiano di Tecnologia , Via Morego 30, Genova 16163, Italy
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564
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He J, Dai J, Li J, Peng X, Niemi AJ. Aspects of structural landscape of human islet amyloid polypeptide. J Chem Phys 2015; 142:045102. [PMID: 25638009 DOI: 10.1063/1.4905586] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The human islet amyloid polypeptide (hIAPP) co-operates with insulin to maintain glycemic balance. It also constitutes the amyloid plaques that aggregate in the pancreas of type-II diabetic patients. We have performed extensive in silico investigations to analyse the structural landscape of monomeric hIAPP, which is presumed to be intrinsically disordered. For this, we construct from first principles a highly predictive energy function that describes a monomeric hIAPP observed in a nuclear magnetic resonance experiment, as a local energy minimum. We subject our theoretical model of hIAPP to repeated heating and cooling simulations, back and forth between a high temperature regime where the conformation resembles a random walker and a low temperature limit where no thermal motions prevail. We find that the final low temperature conformations display a high level of degeneracy, in a manner which is fully in line with the presumed intrinsically disordered character of hIAPP. In particular, we identify an isolated family of α-helical conformations that might cause the transition to amyloidosis, by nucleation.
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Affiliation(s)
- Jianfeng He
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jin Dai
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Jing Li
- Institute of Biopharmaceutical Research, Yangtze River Pharmaceutical Group Beijing Haiyan Pharmaceutical Co., Ltd, Beijing 102206, China
| | - Xubiao Peng
- Department of Physics and Astronomy, Uppsala University, P.O. Box 803, S-75108 Uppsala, Sweden
| | - Antti J Niemi
- School of Physics, Beijing Institute of Technology, Beijing 100081, People's Republic of China
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565
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Donabedian PL, Pham TK, Whitten DG, Chi EY. Oligo(p-phenylene ethynylene) Electrolytes: A Novel Molecular Scaffold for Optical Tracking of Amyloids. ACS Chem Neurosci 2015; 6:1526-35. [PMID: 26114931 DOI: 10.1021/acschemneuro.5b00086] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Finding new optical probes to detect and track amyloid protein aggregates is key to understanding and defeating the myriad of neurodegenerative and other diseases associated with these misfolded proteins. Herein we report that a series of fluorescent, soluble oligo(p-phenylene ethynylene)s (OPEs) are able to detect amyloids in vitro by massive binding-activated superluminescence, with low micromolar affinity and high selectivity for the amyloid conformer. The OPEs track the kinetics of amyloid fibril formation from native hen egg white lysozyme (HEWL) similarly to thioflavin T (ThT), and the dependence of binding affinity on OPE length supports the theory of a linear binding groove. We hypothesize, based on spectral properties, induced circular dichroism, and previous work in analogous systems, that the fluorescence turn-on mechanism is a combination of the reduction of static solvent-mediated quenching at the ethyl ester end groups of the phenylene ethynylene fluorophore and the formation of chiral J-type aggregates templated on the amyloid fibril surface.
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Affiliation(s)
- Patrick L. Donabedian
- The Nanoscience and Microsystems Engineering Program, ‡Department of Chemical
and Biological Engineering, and §The Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Thao K. Pham
- The Nanoscience and Microsystems Engineering Program, ‡Department of Chemical
and Biological Engineering, and §The Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - David G. Whitten
- The Nanoscience and Microsystems Engineering Program, ‡Department of Chemical
and Biological Engineering, and §The Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Eva Y. Chi
- The Nanoscience and Microsystems Engineering Program, ‡Department of Chemical
and Biological Engineering, and §The Center for Biomedical Engineering, University of New Mexico, Albuquerque, New Mexico 87131, United States
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566
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Fortin JS, Benoit-Biancamano MO, C-Gaudreault R. Discovery of ethyl urea derivatives as inhibitors of islet amyloid polypeptide fibrillization and cytotoxicity. Can J Physiol Pharmacol 2015; 94:341-6. [PMID: 26679837 DOI: 10.1139/cjpp-2015-0204] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Islet amyloid polypeptide (IAPP) has been shown to form amyloid deposits in pancreatic islets, thereby furthering type 2 diabetes disease progression. Further discovery of new molecules is needed to create a diverse set of molecules that impede pancreatic amyloidosis. We have recently designed and synthesized N-phenyl-N'-(2-ethyl)ureas (EU) that are non-cytotoxic small molecules, to evaluate the role of the aryl-substituted moiety on the inhibition of hIAPP fibrillization. Several EUs were tested in vitro for their anti-amyloidogenic activity using the fluorometric ThT assay, the photo-induced cross-linking (PIUCP) assay, and cell survival assay in pancreatic MIN-6 cells. EU-362 and EU-418 were able to significantly inhibit the formation of hIAPP fibrils and protected cells from amyloid cytotoxic effects. Our results suggest that increasing the nucleophilic potency of the aryl moiety significantly enhances the anti-amyloidogenic activity of the molecules.
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Affiliation(s)
- Jessica S Fortin
- a Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Marie-Odile Benoit-Biancamano
- a Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - René C-Gaudreault
- b CR CHU de Québec, Axe oncologie, Hôpital Saint-François d'Assise, 10 rue de l'Espinay, Québec, QC G1L 3L5, Canada
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567
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vandenAkker CC, Deckert-Gaudig T, Schleeger M, Velikov KP, Deckert V, Bonn M, Koenderink GH. Nanoscale Heterogeneity of the Molecular Structure of Individual hIAPP Amyloid Fibrils Revealed with Tip-Enhanced Raman Spectroscopy. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:4131-4139. [PMID: 25952953 DOI: 10.1002/smll.201500562] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Indexed: 06/04/2023]
Abstract
Type 2 diabetes mellitus is characterized by the pathological deposition of fibrillized protein, known as amyloids. It is thought that oligomers and/or amyloid fibrils formed from human islet amyloid polypeptide (hIAPP or amylin) cause cell death by membrane damage. The molecular structure of hIAPP amyloid fibrils is dominated by β-sheet structure, as probed with conventional infrared and Raman vibrational spectroscopy. However, with these techniques it is not possible to distinguish between the core and the surface structure of the fibrils. Since the fibril surface crucially affects amyloid toxicity, it is essential to know its structure. Here the surface molecular structure and amino acid residue composition of hIAPP fibrils are specifically probed with nanoscale resolution using tip-enhanced Raman spectroscopy (TERS). The fibril surface mainly contains unordered or α-helical structures, in contrast to the β-sheet-rich core. This experimentally validates recent models of hIAPP amyloids based on NMR measurements. Spatial mapping of the surface structure reveals a highly heterogeneous surface structure. Finally, TERS can probe fibrils formed on a lipid interface, which is more representative of amyloids in vivo.
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Affiliation(s)
| | - Tanja Deckert-Gaudig
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
| | - Michael Schleeger
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
| | - Krassimir P Velikov
- Soft Condensed Matter, Debye Institute for Nanomaterials Science, Department of Physics and Astronomy, Utrecht University, Princetonplein 5, 3584, CC, Utrecht, The Netherlands
- Unilever Research Labs, NL-3133 AT Vlaardingen, The Netherlands
| | - Volker Deckert
- Leibniz Institute of Photonic Technology, Albert-Einstein-Straße 9, 07745, Jena, Germany
- Institute for Physical Chemistry and Abbe Center of Photonics, University of Jena, Helmholtzweg 4, 07743, Jena, Germany
| | - Mischa Bonn
- Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany
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568
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Lambert R, Srodulski S, Peng X, Margulies KB, Despa F, Despa S. Intracellular Na+ Concentration ([Na+]i) Is Elevated in Diabetic Hearts Due to Enhanced Na+-Glucose Cotransport. J Am Heart Assoc 2015; 4:e002183. [PMID: 26316524 PMCID: PMC4599504 DOI: 10.1161/jaha.115.002183] [Citation(s) in RCA: 74] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Background Intracellular Na+ concentration ([Na+]i) regulates Ca2+ cycling, contractility, metabolism, and electrical stability of the heart. [Na+]i is elevated in heart failure, leading to arrhythmias and oxidative stress. We hypothesized that myocyte [Na+]i is also increased in type 2 diabetes (T2D) due to enhanced activity of the Na+–glucose cotransporter. Methods and Results To test this hypothesis, we used myocardial tissue from humans with T2D and a rat model of late-onset T2D (HIP rat). Western blot analysis showed increased Na+–glucose cotransporter expression in failing hearts from T2D patients compared with nondiabetic persons (by 73±13%) and in HIP rat hearts versus wild-type (WT) littermates (by 61±8%). [Na+]i was elevated in HIP rat myocytes both at rest (14.7±0.9 versus 11.4±0.7 mmol/L in WT) and during electrical stimulation (17.3±0.8 versus 15.0±0.7 mmol/L); however, the Na+/K+-pump function was similar in HIP and WT cells, suggesting that higher [Na+]i is due to enhanced Na+ entry in diabetic hearts. Indeed, Na+ influx was significantly larger in myocytes from HIP versus WT rats (1.77±0.11 versus 1.29±0.06 mmol/L per minute). Na+–glucose cotransporter inhibition with phlorizin or glucose-free solution greatly reduced Na+ influx in HIP myocytes (to 1.20±0.16 mmol/L per minute), whereas it had no effect in WT cells. Phlorizin also significantly decreased glucose uptake in HIP myocytes (by 33±9%) but not in WT, indicating an increased reliance on the Na+–glucose cotransporter for glucose uptake in T2D hearts. Conclusions Myocyte Na+–glucose cotransport is enhanced in T2D, which increases Na+ influx and causes Na+ overload. Higher [Na+]i may contribute to arrhythmogenesis and oxidative stress in diabetic hearts.
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Affiliation(s)
- Rebekah Lambert
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Sarah Srodulski
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Xiaoli Peng
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Kenneth B Margulies
- Cardiovascular Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA (K.B.M.)
| | - Florin Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
| | - Sanda Despa
- Department of Pharmacology and Nutritional Sciences, University of Kentucky, Lexington, KY (R.L., S.S., X.P., F.D., S.D.)
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569
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Jandhyala SM, Talukdar R, Subramanyam C, Vuyyuru H, Sasikala M, Reddy DN. Role of the normal gut microbiota. World J Gastroenterol 2015; 21:8787-8803. [PMID: 26269668 PMCID: PMC4528021 DOI: 10.3748/wjg.v21.i29.8787] [Citation(s) in RCA: 1554] [Impact Index Per Article: 172.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2014] [Revised: 05/10/2015] [Accepted: 07/03/2015] [Indexed: 02/06/2023] Open
Abstract
Relation between the gut microbiota and human health is being increasingly recognised. It is now well established that a healthy gut flora is largely responsible for overall health of the host. The normal human gut microbiota comprises of two major phyla, namely Bacteroidetes and Firmicutes. Though the gut microbiota in an infant appears haphazard, it starts resembling the adult flora by the age of 3 years. Nevertheless, there exist temporal and spatial variations in the microbial distribution from esophagus to the rectum all along the individual’s life span. Developments in genome sequencing technologies and bioinformatics have now enabled scientists to study these microorganisms and their function and microbe-host interactions in an elaborate manner both in health and disease. The normal gut microbiota imparts specific function in host nutrient metabolism, xenobiotic and drug metabolism, maintenance of structural integrity of the gut mucosal barrier, immunomodulation, and protection against pathogens. Several factors play a role in shaping the normal gut microbiota. They include (1) the mode of delivery (vaginal or caesarean); (2) diet during infancy (breast milk or formula feeds) and adulthood (vegan based or meat based); and (3) use of antibiotics or antibiotic like molecules that are derived from the environment or the gut commensal community. A major concern of antibiotic use is the long-term alteration of the normal healthy gut microbiota and horizontal transfer of resistance genes that could result in reservoir of organisms with a multidrug resistant gene pool.
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570
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Shi F, Kouadir M, Yang Y. NALP3 inflammasome activation in protein misfolding diseases. Life Sci 2015; 135:9-14. [DOI: 10.1016/j.lfs.2015.05.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2015] [Revised: 04/09/2015] [Accepted: 05/03/2015] [Indexed: 01/26/2023]
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571
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Spijker HS, Song H, Ellenbroek JH, Roefs MM, Engelse MA, Bos E, Koster AJ, Rabelink TJ, Hansen BC, Clark A, Carlotti F, de Koning EJP. Loss of β-Cell Identity Occurs in Type 2 Diabetes and Is Associated With Islet Amyloid Deposits. Diabetes 2015; 64:2928-38. [PMID: 25918235 DOI: 10.2337/db14-1752] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Accepted: 04/10/2015] [Indexed: 01/06/2023]
Abstract
Loss of pancreatic islet β-cell mass and β-cell dysfunction are central in the development of type 2 diabetes (T2DM). We recently showed that mature human insulin-containing β-cells can convert into glucagon-containing α-cells ex vivo. This loss of β-cell identity was characterized by the presence of β-cell transcription factors (Nkx6.1, Pdx1) in glucagon(+) cells. Here, we investigated whether the loss of β-cell identity also occurs in vivo, and whether it is related to the presence of (pre)diabetes in humans and nonhuman primates. We observed an eight times increased frequency of insulin(+) cells coexpressing glucagon in donors with diabetes. Up to 5% of the cells that were Nkx6.1(+) but insulin(-) coexpressed glucagon, which represents a five times increased frequency compared with the control group. This increase in bihormonal and Nkx6.1(+)glucagon(+)insulin(-) cells was also found in islets of diabetic macaques. The higher proportion of bihormonal cells and Nkx6.1(+)glucagon(+)insulin(-) cells in macaques and humans with diabetes was correlated with the presence and extent of islet amyloidosis. These data indicate that the loss of β-cell identity occurs in T2DM and could contribute to the decrease of functional β-cell mass. Maintenance of β-cell identity is a potential novel strategy to preserve β-cell function in diabetes.
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Affiliation(s)
- H Siebe Spijker
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Heein Song
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Johanne H Ellenbroek
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Maaike M Roefs
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Marten A Engelse
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Erik Bos
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Abraham J Koster
- Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, the Netherlands
| | - Ton J Rabelink
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Barbara C Hansen
- Departments of Internal Medicine and Pediatrics, Morsani College of Medicine, University of South Florida, Tampa, FL
| | - Anne Clark
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, U.K
| | - Françoise Carlotti
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - Eelco J P de Koning
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands Hubrecht Institute, Utrecht, the Netherlands
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572
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Berglund E, Daré E, Branca RM, Akcakaya P, Fröbom R, Berggren PO, Lui WO, Larsson C, Zedenius J, Orre L, Lehtiö J, Kim J, Bränström R. Secretome protein signature of human gastrointestinal stromal tumor cells. Exp Cell Res 2015; 336:158-70. [DOI: 10.1016/j.yexcr.2015.05.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/04/2015] [Accepted: 05/05/2015] [Indexed: 01/03/2023]
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573
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Vandal M, White PJ, Chevrier G, Tremblay C, St.‐Amour I, Planel E, Marette A, Calon F. Age‐dependent impairment of glucose tolerance in the 3xTg‐AD mouse model of Alzheimer's disease. FASEB J 2015; 29:4273-84. [DOI: 10.1096/fj.14-268482] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 06/22/2015] [Indexed: 01/21/2023]
Affiliation(s)
- Milene Vandal
- Faculté de PharmacieUniversité LavalQuébecQuébecCanada
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université LavalQuébecQuébecCanada
- Axe NeurosciencesCentre de Recherche du Centre Hospitalier de l'Université Laval (CHUL)QuébecQuébecCanada
| | - Phillip J. White
- Faculté de PharmacieUniversité LavalQuébecQuébecCanada
- Département de Medicine, Axe de Cardiologie, Faculté de MédicineUniversité LavalQuébecQuébecCanada
- Sarah W. Stedman Nutrition and Metabolism Center, Duke Molecular Physiology InstituteDurhamNorth CarolinaUSA
| | - Geneviève Chevrier
- Département de Medicine, Axe de Cardiologie, Faculté de MédicineUniversité LavalQuébecQuébecCanada
- Institut Universitaire de Pneumologie et de CardiologieQuébecQuébecCanada
| | - Cyntia Tremblay
- Axe NeurosciencesCentre de Recherche du Centre Hospitalier de l'Université Laval (CHUL)QuébecQuébecCanada
| | - Isabelle St.‐Amour
- Faculté de PharmacieUniversité LavalQuébecQuébecCanada
- Axe NeurosciencesCentre de Recherche du Centre Hospitalier de l'Université Laval (CHUL)QuébecQuébecCanada
| | - Emmanuel Planel
- Axe NeurosciencesCentre de Recherche du Centre Hospitalier de l'Université Laval (CHUL)QuébecQuébecCanada
| | - Andre Marette
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université LavalQuébecQuébecCanada
- Département de Medicine, Axe de Cardiologie, Faculté de MédicineUniversité LavalQuébecQuébecCanada
- Institut Universitaire de Pneumologie et de CardiologieQuébecQuébecCanada
| | - Frederic Calon
- Faculté de PharmacieUniversité LavalQuébecQuébecCanada
- Institut des Nutraceutiques et des Aliments Fonctionnels, Université LavalQuébecQuébecCanada
- Axe NeurosciencesCentre de Recherche du Centre Hospitalier de l'Université Laval (CHUL)QuébecQuébecCanada
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574
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Lutz TA, Meyer U. Amylin at the interface between metabolic and neurodegenerative disorders. Front Neurosci 2015; 9:216. [PMID: 26136651 PMCID: PMC4468610 DOI: 10.3389/fnins.2015.00216] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 05/29/2015] [Indexed: 12/14/2022] Open
Abstract
The pancreatic peptide amylin is best known for its role as a satiation hormone in the control of food intake and as the major component of islet amyloid deposits in the pancreatic islets of patients with type 2 diabetes mellitus (T2DM). Epidemiological studies have established a clear association between metabolic and neurodegenerative disorders in general, and between T2DM and Alzheimer's disease (AD) in particular. Here, we discuss that amylin may be an important player acting at the interface between these metabolic and neurodegenerative disorders. Abnormal amylin production is a hallmark peripheral pathology both in the early (pre-diabetic) and late phases of T2DM, where hyperamylinemic (early phase) and hypoamylinemic (late phase) conditions coincide with hyper- and hypo-insulinemia, respectively. Moreover, there are notable biochemical similarities between amylin and β-amyloids (Aβ), which are both prone to amyloid plaque formation and to cytotoxic effects. Amylin's propensity to form amyloid plaques is not restricted to pancreatic islet cells, but readily extends to the CNS, where it has been found to co-localize with Aβ plaques in at least a subset of AD patients. Hence, amylin may constitute a “second amyloid” in neurodegenerative disorders such as AD. We further argue that hyperamylinemic conditions may be more relevant for the early processes of amyloid formation in the CNS, whereas hypoamylinemic conditions may be more strongly associated with late stages of central amyloid pathologies. Advancing our understanding of these temporal relationships may help to establish amylin-based interventions in the treatment of AD and other neurodegenerative disorders with metabolic comorbidities.
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Affiliation(s)
- Thomas A Lutz
- Institute of Veterinary Physiology, University of Zurich Zurich, Switzerland ; Zurich Center of Integrative Human Physiology, University of Zurich Zurich, Switzerland
| | - Urs Meyer
- Institute of Veterinary Pharmacology and Toxicology, University of Zurich Zurich, Switzerland
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575
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Oskarsson ME, Singh K, Wang J, Vlodavsky I, Li JP, Westermark GT. Heparan Sulfate Proteoglycans Are Important for Islet Amyloid Formation and Islet Amyloid Polypeptide-induced Apoptosis. J Biol Chem 2015; 290:15121-32. [PMID: 25922077 PMCID: PMC4463455 DOI: 10.1074/jbc.m114.631697] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Revised: 04/16/2015] [Indexed: 12/23/2022] Open
Abstract
Deposition of β cell toxic islet amyloid is a cardinal finding in type 2 diabetes. In addition to the main amyloid component islet amyloid polypeptide (IAPP), heparan sulfate proteoglycan is constantly present in the amyloid deposit. Heparan sulfate (HS) side chains bind to IAPP, inducing conformational changes of the IAPP structure and an acceleration of fibril formation. We generated a double-transgenic mouse strain (hpa-hIAPP) that overexpresses human heparanase and human IAPP but is deficient of endogenous mouse IAPP. Culture of hpa-hIAPP islets in 20 mm glucose resulted in less amyloid formation compared with the amyloid load developed in cultured islets isolated from littermates expressing human IAPP only. A similar reduction of amyloid was achieved when human islets were cultured in the presence of heparin fragments. Furthermore, we used CHO cells and the mutant CHO pgsD-677 cell line (deficient in HS synthesis) to explore the effect of cellular HS on IAPP-induced cytotoxicity. Seeding of IAPP aggregation on CHO cells resulted in caspase-3 activation and apoptosis that could be prevented by inhibition of caspase-8. No IAPP-induced apoptosis was seen in HS-deficient CHO pgsD-677 cells. These results suggest that β cell death caused by extracellular IAPP requires membrane-bound HS. The interaction between HS and IAPP or the subsequent effects represent a possible therapeutic target whose blockage can lead to a prolonged survival of β cells.
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Affiliation(s)
| | | | - Jian Wang
- Ningxia People's Hospital, Yinchuan 750021, China, and Medical Biochemistry and Microbiology, Uppsala University, Box 571, 75123 Uppsala, Sweden
| | - Israel Vlodavsky
- the Cancer and Vascular Biology Research Center, The Bruce Rappaport Faculty of Medicine, Technion, Haifa 31096, Israel
| | - Jin-Ping Li
- Medical Biochemistry and Microbiology, Uppsala University, Box 571, 75123 Uppsala, Sweden,
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576
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Colvin MT, Silvers R, Frohm B, Su Y, Linse S, Griffin RG. High resolution structural characterization of Aβ42 amyloid fibrils by magic angle spinning NMR. J Am Chem Soc 2015; 137:7509-18. [PMID: 26001057 PMCID: PMC4623963 DOI: 10.1021/jacs.5b03997] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
![]()
The presence of amyloid plaques composed
of amyloid beta (Aβ)
fibrils is a hallmark of Alzheimer’s disease (AD). The Aβ
peptide is present as several length variants with two common alloforms
consisting of 40 and 42 amino acids, denoted Aβ1–40 and Aβ1–42, respectively. While there have
been numerous reports that structurally characterize fibrils of Aβ1–40, very little is known about the structure of amyloid
fibrils of Aβ1–42, which are considered the
more toxic alloform involved in AD. We have prepared isotopically 13C/15N labeled AβM01–42 fibrils in vitro from recombinant protein and examined their 13C–13C and 13C–15N magic angle spinning (MAS) NMR spectra. In contrast to several
other studies of Aβ fibrils, we observe spectra with excellent
resolution and a single set of chemical shifts, suggesting the presence
of a single fibril morphology. We report the initial structural characterization
of AβM01–42 fibrils utilizing 13C and 15N shift assignments of 38 of the 43 residues,
including the backbone and side chains, obtained through a series
of cross-polarization based 2D and 3D 13C–13C, 13C–15N MAS NMR experiments for rigid
residues along with J-based 2D TOBSY experiments for dynamic residues.
We find that the first ∼5 residues are dynamic and most efficiently
detected in a J-based TOBSY spectrum. In contrast, residues 16–42
are easily observed in cross-polarization experiments and most likely
form the amyloid core. Calculation of ψ and φ dihedral
angles from the chemical shift assignments indicate that 4 β-strands
are present in the fibril’s secondary structure.
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Affiliation(s)
- Michael T Colvin
- †Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Robert Silvers
- †Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Birgitta Frohm
- ‡Department of Biochemistry and Structural Biology, Lund University, SE22100 Lund, Sweden
| | - Yongchao Su
- †Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
| | - Sara Linse
- ‡Department of Biochemistry and Structural Biology, Lund University, SE22100 Lund, Sweden
| | - Robert G Griffin
- †Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States
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577
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Potter KJ, Werner I, Denroche HC, Montane J, Plesner A, Chen Y, Lei D, Soukhatcheva G, Warnock GL, Oberholzer J, Fraser PE, Verchere CB. Amyloid formation in human islets is enhanced by heparin and inhibited by heparinase. Am J Transplant 2015; 15:1519-30. [PMID: 25833002 DOI: 10.1111/ajt.13134] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 11/16/2014] [Accepted: 11/16/2014] [Indexed: 01/25/2023]
Abstract
Islet transplantation is a promising therapy for patients with diabetes, but its long-term success is limited by many factors, including the formation of islet amyloid deposits. Heparin is employed in clinical islet transplantation to reduce clotting but also promotes fibrillization of amyloidogenic proteins. We hypothesized that heparin treatment of islets during pre-transplant culture may enhance amyloid formation leading to beta cell loss and graft dysfunction. Heparin promoted the fibrillization of human islet amyloid polypeptide (IAPP) and enhanced its toxicity to INS-1 beta cells. Heparin increased amyloid deposition in cultured human islets, but surprisingly decreased islet cell apoptosis. Treatment of human islets with heparin prior to transplantation increased the likelihood of graft failure. Removal of islet heparan sulfate glycosaminoglycans, which localize with islet amyloid deposits in type 2 diabetes, by heparinase treatment decreased amyloid deposition and protected against islet cell death. These findings raise the possibility that pretransplant treatment of human islets with heparin could potentiate IAPP aggregation and amyloid formation and may be detrimental to subsequent graft function.
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Affiliation(s)
- K J Potter
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - I Werner
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - H C Denroche
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - J Montane
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - A Plesner
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Y Chen
- Department of Medical Biophysics, Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, ON, Canada
| | - D Lei
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - G Soukhatcheva
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada
| | - G L Warnock
- Surgery, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - J Oberholzer
- Surgery, and Bioengineering, University of Illinois, Chicago, IL
| | - P E Fraser
- Department of Medical Biophysics, Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, ON, Canada
| | - C B Verchere
- Departments of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, BC, Canada.,Surgery, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada
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578
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Hjuler ST, Andreassen KV, Gydesen S, Karsdal MA, Henriksen K. KBP-042 improves bodyweight and glucose homeostasis with indices of increased insulin sensitivity irrespective of route of administration. Eur J Pharmacol 2015; 762:229-38. [PMID: 26027795 DOI: 10.1016/j.ejphar.2015.05.051] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 05/07/2015] [Accepted: 05/26/2015] [Indexed: 01/24/2023]
Abstract
KBP-042 is a synthetic peptide dual amylin- and calcitonin-receptor agonist (DACRA) developed to treat type 2 diabetes by inducing a significant weight loss while improving glucose homeostasis. In this study the aim was to compare two different formulations: An oral formulation (1mg/kg) to subcutaneous formulations of KBP-042 (2.5μg/kg, 5.0μg/kg and 7.5μg/kg) with comparable pharmacokinetic profiles. Furthermore to examine if differences in mode of action between the two different routes of administration in high-fat fed Sprague-Dawley rats were present. It was established that the subcutaneous administrations of KBP-042 were able to dose-dependently cause a significant weight-loss, reduce food intake, and improve glucose homeostasis without increasing insulin secretion, effects comparable to those observed with oral administration. At the same time, s.c. KBP-042 suppressed the inappropriate glucagon response better than the oral formulation. Furthermore, KBP-042 was found to reduce incretins GLP-1 and GIP and considerably, improve gastric emptying, and to alleviate leptin resistance, as well as insulin resistance. In conclusion, the subcutaneous route of administration was found to have the same beneficial effects on blood glucose homeostasis and weight loss as well as resistance towards important insulin and leptin, albeit with a markedly lower variation in both exposure and biological responses. These data support the application of subcutaneously delivered peptide for mechanistic studies, and highlight the potential of developing s.c. KBP-042 as a therapy for T2D.
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Affiliation(s)
- Sara T Hjuler
- Nordic Bioscience, Herlev Hovedgade 207, DK-2730 Herlev, Denmark.
| | - Kim V Andreassen
- Nordic Bioscience, Herlev Hovedgade 207, DK-2730 Herlev, Denmark
| | - Sofie Gydesen
- Nordic Bioscience, Herlev Hovedgade 207, DK-2730 Herlev, Denmark
| | - Morten A Karsdal
- Nordic Bioscience, Herlev Hovedgade 207, DK-2730 Herlev, Denmark
| | - Kim Henriksen
- Nordic Bioscience, Herlev Hovedgade 207, DK-2730 Herlev, Denmark
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579
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Louros NN, Tsiolaki PL, Zompra AA, Pappa EV, Magafa V, Pairas G, Cordopatis P, Cheimonidou C, Trougakos IP, Iconomidou VA, Hamodrakas SJ. Structural studies and cytotoxicity assays of “aggregation-prone” IAPP8-16and its non-amyloidogenic variants suggest its important role in fibrillogenesis and cytotoxicity of human amylin. Biopolymers 2015; 104:196-205. [DOI: 10.1002/bip.22650] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 03/10/2015] [Accepted: 03/30/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Nikolaos N. Louros
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
| | - Paraskevi L. Tsiolaki
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
| | | | - Eleni V. Pappa
- Department of Pharmacy; University of Patras; Patras 26504 Greece
| | - Vassiliki Magafa
- Department of Pharmacy; University of Patras; Patras 26504 Greece
| | - George Pairas
- Department of Pharmacy; University of Patras; Patras 26504 Greece
| | - Paul Cordopatis
- Department of Pharmacy; University of Patras; Patras 26504 Greece
| | - Christina Cheimonidou
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
| | - Ioannis P. Trougakos
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
| | - Vassiliki A. Iconomidou
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
| | - Stavros J. Hamodrakas
- Department of Cell Biology and Biophysics; Faculty of Biology, University of Athens; Panepistimiopolis Athens 157 01 Greece
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580
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Nath A, Schlamadinger DE, Rhoades E, Miranker AD. Structure-Based Small Molecule Modulation of a Pre-Amyloid State: Pharmacological Enhancement of IAPP Membrane-Binding and Toxicity. Biochemistry 2015; 54:3555-64. [PMID: 25966003 DOI: 10.1021/acs.biochem.5b00052] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Islet amyloid polypeptide (IAPP) is a peptide hormone whose pathological self-assembly is a hallmark of the progression of type II diabetes. IAPP-membrane interactions catalyze its higher-order self-assembly and also underlie its toxic effects toward cells. While there is great interest in developing small molecule reagents capable of altering the structure and behavior of oligomeric, membrane-bound IAPP, the dynamic and heterogeneous nature of this ensemble makes it recalcitrant to traditional approaches. Here, we build on recent insights into the nature of membrane-bound states and develop a combined computational and experimental strategy to address this problem. The generalized structural approach efficiently identified diverse compounds from large commercial libraries with previously unrecognized activities toward the gain-of-function behaviors of IAPP. The use of appropriate computational prescreening reduced the experimental burden by orders of magnitude relative to unbiased high-throughput screening. We found that rationally targeting experimentally derived models of membrane-bound dimers identified several compounds that demonstrate the remarkable ability to enhance IAPP-membrane binding and one compound that enhances IAPP-mediated cytotoxicity. Taken together, these findings imply that membrane binding per se is insufficient to generate cytotoxicity; instead, enhanced sampling of rare states within the membrane-bound ensemble may potentiate IAPP's toxic effects.
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Affiliation(s)
- Abhinav Nath
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, United States
| | - Diana E Schlamadinger
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, United States
| | - Elizabeth Rhoades
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, United States
| | - Andrew D Miranker
- Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, Connecticut 06520-8114, United States
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581
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Mukherjee A, Morales-Scheihing D, Butler PC, Soto C. Type 2 diabetes as a protein misfolding disease. Trends Mol Med 2015; 21:439-49. [PMID: 25998900 DOI: 10.1016/j.molmed.2015.04.005] [Citation(s) in RCA: 228] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Revised: 04/16/2015] [Accepted: 04/22/2015] [Indexed: 12/12/2022]
Abstract
Type 2 diabetes (T2D) is a highly prevalent and chronic metabolic disorder. Recent evidence suggests that formation of toxic aggregates of the islet amyloid polypeptide (IAPP) might contribute to β-cell dysfunction and disease. However, the mechanism of protein aggregation and associated toxicity remains unclear. Misfolding, aggregation, and accumulation of diverse proteins in various organs is the hallmark of the group of protein misfolding disorders (PMDs), including highly prevalent illnesses affecting the central nervous system (CNS) such as Alzheimer's disease (AD) and Parkinson's disease (PD). In this review we discuss the current understanding of the mechanisms implicated in the formation of protein aggregates in the endocrine pancreas and associated toxicity in the light of the long-standing knowledge from neurodegenerative disorders associated with protein misfolding.
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Affiliation(s)
- Abhisek Mukherjee
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA
| | - Diego Morales-Scheihing
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA; Universidad de los Andes, Facultad de Medicina, Av. San Carlos de Apoquindo 2200, Las Condes, Santiago, Chile
| | - Peter C Butler
- Larry L. Hillblom Islet Research Center, University of California at Los Angeles, Los Angeles, CA, USA
| | - Claudio Soto
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA.
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582
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Westermark GT, Oskarsson M, Andersson A, Westermark P. Eighty years of research on islet amyloidosis in Uppsala. Ups J Med Sci 2015; 120:117-23. [PMID: 25903284 PMCID: PMC4463485 DOI: 10.3109/03009734.2015.1037032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Marie Oskarsson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Arne Andersson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Per Westermark
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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583
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Smaoui MR, Orland H, Waldispühl J. Probing the binding affinity of amyloids to reduce toxicity of oligomers in diabetes. Bioinformatics 2015; 31:2294-302. [PMID: 25777526 DOI: 10.1093/bioinformatics/btv143] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Accepted: 03/08/2015] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION Amyloids play a role in the degradation of β-cells in diabetes patients. In particular, short amyloid oligomers inject themselves into the membranes of these cells and create pores that disrupt the strictly controlled flow of ions through the membranes. This leads to cell death. Getting rid of the short oligomers either by a deconstruction process or by elongating them into longer fibrils will reduce this toxicity and allow the β-cells to live longer. RESULTS We develop a computational method to probe the binding affinity of amyloid structures and produce an amylin analog that binds to oligomers and extends their length. The binding and extension lower toxicity and β-cell death. The amylin analog is designed through a parsimonious selection of mutations and is to be administered with the pramlintide drug, but not to interact with it. The mutations (T9K L12K S28H T30K) produce a stable native structure, strong binding affinity to oligomers, and long fibrils. We present an extended mathematical model for the insulin-glucose relationship and demonstrate how affecting the concentration of oligomers with such analog is strictly coupled with insulin release and β-cell fitness. AVAILABILITY AND IMPLEMENTATION SEMBA, the tool to probe the binding affinity of amyloid proteins and generate the binding affinity scoring matrices and R-scores is available at: http://amyloid.cs.mcgill.ca
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Affiliation(s)
- Mohamed Raef Smaoui
- School of Computer Science and McGill Center for Bioinformatics, McGill University, Montreal, QC, Canada and
| | - Henri Orland
- Institut de Physique Théorique, CEA-Saclay, 91191 Gif/Yvette Cedex, France
| | - Jérôme Waldispühl
- School of Computer Science and McGill Center for Bioinformatics, McGill University, Montreal, QC, Canada and
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584
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Oskarsson ME, Paulsson JF, Schultz SW, Ingelsson M, Westermark P, Westermark GT. In vivo seeding and cross-seeding of localized amyloidosis: a molecular link between type 2 diabetes and Alzheimer disease. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 185:834-46. [PMID: 25700985 DOI: 10.1016/j.ajpath.2014.11.016] [Citation(s) in RCA: 222] [Impact Index Per Article: 24.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 10/31/2014] [Accepted: 11/06/2014] [Indexed: 01/21/2023]
Abstract
Several proteins have been identified as amyloid forming in humans, and independent of protein origin, the fibrils are morphologically similar. Therefore, there is a potential for structures with amyloid seeding ability to induce both homologous and heterologous fibril growth; thus, molecular interaction can constitute a link between different amyloid forms. Intravenous injection with preformed fibrils from islet amyloid polypeptide (IAPP), proIAPP, or amyloid-beta (Aβ) into human IAPP transgenic mice triggered IAPP amyloid formation in pancreas in 5 of 7 mice in each group, demonstrating that IAPP amyloid could be enhanced through homologous and heterologous seeding with higher efficiency for the former mechanism. Proximity ligation assay was used for colocalization studies of IAPP and Aβ in islet amyloid in type 2 diabetic patients and Aβ deposits in brains of patients with Alzheimer disease. Aβ reactivity was not detected in islet amyloid although islet β cells express AβPP and convertases necessary for Aβ production. By contrast, IAPP and proIAPP were detected in cerebral and vascular Aβ deposits, and presence of proximity ligation signal at both locations showed that the peptides were <40 nm apart. It is not clear whether IAPP present in brain originates from pancreas or is locally produced. Heterologous seeding between IAPP and Aβ shown here may represent a molecular link between type 2 diabetes and Alzheimer disease.
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Affiliation(s)
- Marie E Oskarsson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Johan F Paulsson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | | | - Martin Ingelsson
- Department of Public Health/Geriatrics, Uppsala University, Uppsala, Sweden
| | - Per Westermark
- Department of Immunology, Genetics and Pathology, Uppsala University, Uppsala, Sweden
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585
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Khadra A, Schnell S. Development, growth and maintenance of β-cell mass: models are also part of the story. Mol Aspects Med 2015; 42:78-90. [PMID: 25720614 DOI: 10.1016/j.mam.2015.01.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Revised: 01/26/2015] [Accepted: 01/26/2015] [Indexed: 01/09/2023]
Abstract
Pancreatic β-cells in the islets of Langerhans play a crucial role in regulating glucose homeostasis in the circulation. Loss of β-cell mass or function due to environmental, genetic and immunological factors leads to the manifestation of diabetes mellitus. The mechanisms regulating the dynamics of pancreatic β-cell mass during normal development and diabetes progression are complex. To fully unravel such complexity, experimental and clinical approaches need to be combined with mathematical and computational models. In the natural sciences, mathematical and computational models have aided the identification of key mechanisms underlying the behavior of systems comprising multiple interacting components. A number of mathematical and computational models have been proposed to explain the development, growth and death of pancreatic β-cells. In this review, we discuss some of these models and how their predictions provide novel insight into the mechanisms controlling β-cell mass during normal development and diabetes progression. Lastly, we discuss a handful of the major open questions in the field.
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Affiliation(s)
- Anmar Khadra
- Department of Physiology, McGill University, McIntyre Medical Building, 3655 Promenade Sir William Osler, Montreal, Quebec H3G 1Y6, Canada
| | - Santiago Schnell
- Department of Molecular & Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA; Department of Computational Medicine & Bioinformatics, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA; Brehm Center for Diabetes Research, University of Michigan Medical School, Ann Arbor, Michigan 48105, USA.
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586
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Guo C, Côté S, Mousseau N, Wei G. Distinct helix propensities and membrane interactions of human and rat IAPP(1-19) monomers in anionic lipid bilayers. J Phys Chem B 2015; 119:3366-76. [PMID: 25646717 DOI: 10.1021/jp5111357] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Islet amyloid polypeptide, IAPP or amylin, is a 37-residue peptide hormone coexpressed with insulin by pancreatic β-cells. The aggregation of human IAPP (hIAPP) into amyloid deposits is associated with type II diabetes. Substantial evidence suggests that the interaction of anionic membranes with hIAPP may facilitate peptide aggregation and the N-terminal 1-19 fragment (IAPP(1-19)) plays an important role in peptide-membrane interaction. As a first step to understand how structural differences between human and rat IAPP peptides in membranes may influence the later oligomerization process, we have investigated the structures and orientations of hIAPP(1-19) and the less toxic rIAPP(1-19) (i.e., the H18R mutant of hIAPP(1-19)) monomers in anionic POPG bilayers by performing replica exchange molecular dynamics (REMD) simulations. On the basis of ∼20 μs REMD simulations started from a random coil conformation of the peptide placed in water, we find that unfolded h(r)IAPP(1-19) can insert into the bilayers and the membrane-bound peptide stays mainly at the lipid head-tail interface. hIAPP(1-19) displays higher helix propensity than rIAPP(1-19), especially in the L12-L16 region. The helix is oriented parallel to the bilayer surface and buried in the membrane 0.3-0.8 nm below the phosphorus atoms, consistent with previous electron paramagnetic resonance data. The helical conformation is an amphiphilic helix with its hydrophilic and hydrophobic faces pointing, respectively, to the lipid head and tail regions. The H18R substitution enhances the electrostatic interactions of IAPP(1-19) with the membrane, while it weakens the intrapeptide interactions crucial for helix formation, thus leading to lower helix propensity of rIAPP(1-19). Implications of our simulation results on the membrane-mediated IAPP(1-19) oligomerization are discussed.
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Affiliation(s)
- Cong Guo
- State Key Laboratory of Surface Physics, Key Laboratory for Computational Physical Sciences (MOE), and Department of Physics, Fudan University , 220 Handan Road, Shanghai 200433, China
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587
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Brender JR, Krishnamoorthy J, Sciacca MFM, Vivekanandan S, D'Urso L, Chen J, La Rosa C, Ramamoorthy A. Probing the sources of the apparent irreproducibility of amyloid formation: drastic changes in kinetics and a switch in mechanism due to micellelike oligomer formation at critical concentrations of IAPP. J Phys Chem B 2015; 119:2886-96. [PMID: 25645610 DOI: 10.1021/jp511758w] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aggregation of amyloidogenic proteins is infamous for being highly chaotic, with small variations in conditions sometimes leading to large changes in aggregation rates. Using the amyloidogenic protein IAPP (islet amyloid polypeptide protein, also known as amylin) as an example, we show that a part of this phenomenon may be related to the formation of micellelike oligomers at specific critical concentrations and temperatures. We show that pyrene fluorescence can sensitively detect micellelike oligomer formation by IAPP and discriminate between micellelike oligomers from fibers and monomers, making pyrene one of the few chemical probes specific to a prefibrillar oligomer. We further show that oligomers of this type reversibly form at critical concentrations in the low micromolar range and at specific critical temperatures. Micellelike oligomer formation has several consequences for amyloid formation by IAPP. First, the kinetics of fiber formation increase substantially as the critical concentration is approached but are nearly independent of concentration below it, suggesting a direct role for the oligomers in fiber formation. Second, the critical concentration is strongly correlated with the propensity to form amyloid: higher critical concentrations are observed for both IAPP variants with lower amyloidogenicity and for native IAPP at acidic pH in which aggregation is greatly slowed. Furthermore, using the DEST NMR technique, we show that the pathway of amyloid formation switches as the critical point is approached, with self-interactions primarily near the N-terminus below the critical temperature and near the central region above the critical temperature, reconciling two apparently conflicting views of the initiation of IAPP aggregation.
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Affiliation(s)
- Jeffrey R Brender
- Biophysics, University of Michigan , Ann Arbor, Michigan 48109-1055, United States
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588
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Rodriguez Camargo DC, Tripsianes K, Kapp TG, Mendes J, Schubert J, Cordes B, Reif B. Cloning, expression and purification of the human Islet Amyloid Polypeptide (hIAPP) from Escherichia coli. Protein Expr Purif 2015; 106:49-56. [DOI: 10.1016/j.pep.2014.10.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 10/20/2014] [Accepted: 10/23/2014] [Indexed: 10/24/2022]
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589
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Profit AA, Vedad J, Saleh M, Desamero RZB. Aromaticity and amyloid formation: effect of π-electron distribution and aryl substituent geometry on the self-assembly of peptides derived from hIAPP(22-29). Arch Biochem Biophys 2015; 567:46-58. [PMID: 25524740 PMCID: PMC5490837 DOI: 10.1016/j.abb.2014.12.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Revised: 11/26/2014] [Accepted: 12/07/2014] [Indexed: 10/24/2022]
Abstract
A comprehensive investigation of peptides derived from the 22-29 region of human islet amyloid polypeptide (hIAPP) that contain phenylalanine analogs at position 23 with a variety of electron donating and withdrawing groups, along with heteroaromatic surrogates, has been employed to interrogate how π-electron distribution effects amyloid formation. Kinetic aggregation studies using turbidity measurements indicate that electron rich aromatic ring systems consistently abolish the amyloidogenic propensity of hIAPP(22-29). Electron poor systems modulate the rate of aggregation. Raman and Fourier transform infrared spectroscopy confirm the parallel β-sheet secondary structure of aggregates derived from peptides containing electron poor phenylalanine analogs and provide direct evidence of ring stacking. Transmission electron microscopy confirms the presence of amyloid fibrils. The effect of aryl substituent geometry on peptide self-assembly reveals that the electronic nature of substituents and not their steric profile is responsible for failure of the electron donating group peptides to aggregate. Non-aggregating hIAPP(22-29) peptides were found to inhibit the self-assembly of full-length hIAPP(1-37). The most potent inhibitory peptides contain phenylalanine with the p-amino and p-formamido functionalities. These novel peptides may serve as leads for the development of future aggregation inhibitors. A potential mechanism for inhibition of amylin self-assembly by electron rich (-29) peptides is proposed.
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Affiliation(s)
- Adam A Profit
- York College, Institute for Macromolecular Assemblies and the Graduate Center of the City University of New York, Jamaica, NY 11451, United States.
| | - Jayson Vedad
- York College, Institute for Macromolecular Assemblies and the Graduate Center of the City University of New York, Jamaica, NY 11451, United States
| | - Mohamad Saleh
- York College, Institute for Macromolecular Assemblies and the Graduate Center of the City University of New York, Jamaica, NY 11451, United States
| | - Ruel Z B Desamero
- York College, Institute for Macromolecular Assemblies and the Graduate Center of the City University of New York, Jamaica, NY 11451, United States.
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590
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Fortin JS, Santamaria-Bouvier A, Lair S, Dallaire AD, Benoit-Biancamano MO. Anatomic and molecular characterization of the endocrine pancreas of a teleostean fish: Atlantic wolffish ( Anarhichas lupus). Zool Stud 2015; 54:e21. [PMID: 31966108 DOI: 10.1186/s40555-014-0093-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 12/23/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND The biologic attributes of the endocrine pancreas and the comparative endocrinology of islet amyloid polypeptide (IAPP) of fish are not well described in the literature. This study describes the endocrine pancreasof one teleostean fish. Ten captive Atlantic wolffish (Anarhichas lupus)from the Montreal Biodome were submitted for necropsy and their pancreata were collected. RESULTS Grossly, all the fish pancreata examined contained 1-3 nodules of variable diameter (1-8 mm). Microscopically, the nodules were uniform, highly cellular, and composed of polygonal to elongated cells. Immunofluorescence for pancreatic hormones was performed. The nodules were immunoreactive for insulin most prominent centrally, but with IAPP and glucagon only in the periphery of the nodules. Exocrine pancreas was positive for chromogranin A. Not previously recognized in fish, IAPP immunoreactivity occurred in α, glucagon-containing, cells and did not co-localize with insulin in β cells. The islet tissues were devoid of amyloid deposits. IAPP DNA sequencing was performed to compare the sequence among teleost fish and the potency to form amyloid fibrils. In silico analysis of the amino acid sequences 19-34 revealed that it was not amyloidogenic. CONCLUSIONS Amyloidosis of pancreatic islets would not be expected as a spontaneous disease in the Atlantic wolffish. Our study underlines that this teleost fish is a potential candidate for pancreatic xenograft research.
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Affiliation(s)
- Jessica S Fortin
- Département de pathologie et de microbiologie, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Ariane Santamaria-Bouvier
- Département des sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Stéphane Lair
- Département des sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - André D Dallaire
- Département de pathologie et de microbiologie, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
| | - Marie-Odile Benoit-Biancamano
- Département de pathologie et de microbiologie, Faculté de médecine vétérinaire, Université de Montréal, 3200 Sicotte, Saint-Hyacinthe, QC J2S 2M2, Canada
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591
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Sun D, Forsman J, Woodward CE. Amphipathic membrane-active peptides recognize and stabilize ruptured membrane pores: exploring cause and effect with coarse-grained simulations. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:752-761. [PMID: 25490714 DOI: 10.1021/la5038266] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Induction of membrane pores has been suggested as the common molecular action by which a variety of amphipathic membrane-active peptides cause damage to cells. In this study, we have performed coarse-grained molecular dynamics simulations to establish two clear molecular processes that seem critical for the activity of amphipathic peptides. They are (i) the recognition and (ii) the stabilization of ruptured membrane pores. By considering 12 structurally different peptide types, we reveal that peptide secondary structure content, hydrophobicity, and length are important physicochemical factors that allow amphipathic peptides to aggregate in and stabilize ruptured membrane pores. The simulated inner diameters of peptide-stabilized membrane pores are in good agreement with available experimental data. However, the orientations of α-helical peptides in the membrane pore were found to be quite dispersed. This supports recent challenges to the traditional depictions to peptide orientations in the classical toroidal and barrel-stave pore models.
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Affiliation(s)
- Delin Sun
- School of Physical, Environmental and Mathematical Sciences, University of New South Wales , Canberra ACT 2600, Australia
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592
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Tu LH, Young LM, Wong AG, Ashcroft AE, Radford SE, Raleigh DP. Mutational analysis of the ability of resveratrol to inhibit amyloid formation by islet amyloid polypeptide: critical evaluation of the importance of aromatic-inhibitor and histidine-inhibitor interactions. Biochemistry 2015; 54:666-76. [PMID: 25531836 PMCID: PMC4310630 DOI: 10.1021/bi501016r] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The process of amyloid formation by the normally soluble hormone islet amyloid polypeptide (IAPP) contributes to β-cell death in type 2 diabetes and in islet transplants. There are no clinically approved inhibitors of islet amyloidosis, and the mode of action of existing inhibitors is not well-understood. Resveratrol, a natural polyphenol, has been reported to inhibit amyloid formation by IAPP and by the Alzheimer's disease Aβ peptide. The mechanism of action of this compound is not known, nor is its mode of interaction with IAPP. In this study, we use a series of IAPP variants to examine possible interactions between resveratrol and IAPP. Fluorescence assays, transmission electron microscopy, and mass spectrometry demonstrate that resveratrol is much less effective as an inhibitor of IAPP amyloid formation than the polyphenol (-)-epigallocatechin 3-gallate (EGCG) and, unlike EGCG, does not significantly disaggregate preformed IAPP amyloid fibrils. Resveratrol is also shown to interfere with thioflavin-T assays. His-18 mutants, a truncation mutant, mutants of each of the aromatic residues, and mutants of Arg-11 of IAPP were examined. Mutation of His to Gln or Leu weakens the ability of resveratrol to inhibit amyloid formation by IAPP, as do mutations of Arg-11, Phe-15, or Tyr-37 to Leu, and truncation to form the variant Ac 8-37-IAPP, which removes the first seven residues to eliminate Lys-1 and the N-terminal amino group. In contrast, replacement of Phe-23 with Leu has a smaller effect. The data highlight Phe-15, His-18, and Tyr-37 as being important for IAPP-resveratrol interactions and are consistent with a potential role of the N-terminus and Arg-11 in polypeptide-resveratrol interactions.
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Affiliation(s)
- Ling-Hsien Tu
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
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593
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Abderrazak A, Syrovets T, Couchie D, El Hadri K, Friguet B, Simmet T, Rouis M. NLRP3 inflammasome: from a danger signal sensor to a regulatory node of oxidative stress and inflammatory diseases. Redox Biol 2015; 4:296-307. [PMID: 25625584 PMCID: PMC4315937 DOI: 10.1016/j.redox.2015.01.008] [Citation(s) in RCA: 524] [Impact Index Per Article: 58.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 01/11/2015] [Accepted: 01/12/2015] [Indexed: 02/07/2023] Open
Abstract
IL-1β production is critically regulated by cytosolic molecular complexes, termed inflammasomes. Different inflammasome complexes have been described to date. While all inflammasomes recognize certain pathogens, it is the distinctive feature of NLRP3 inflammasome to be activated by many and diverse stimuli making NLRP3 the most versatile, and importantly also the most clinically implicated inflammasome. However, NLRP3 activation has remained the most enigmatic. It is not plausible that the intracellular NLRP3 receptor is able to detect all of its many and diverse triggers through direct interactions; instead, it is discussed that NLRP3 is responding to certain generic cellular stress-signals induced by the multitude of molecules that trigger its activation. An ever increasing number of studies link the sensing of cellular stress signals to a direct pathophysiological role of NLRP3 activation in a wide range of autoinflammatory and autoimmune disorders, and thus provide a novel mechanistic rational, on how molecules trigger and support sterile inflammatory diseases. A vast interest has created to unravel how NLRP3 becomes activated, since mechanistic insight is the prerequisite for a knowledge-based development of therapeutic intervention strategies that specifically target the NLRP3 triggered IL-1β production. In this review, we have updated knowledge on NLRP3 inflammasome assembly and activation and on the pyrin domain in NLRP3 that could represent a drug target to treat sterile inflammatory diseases. We have reported mutations in NLRP3 that were found to be associated with certain diseases. In addition, we have reviewed the functional link between NLRP3 inflammasome, the regulator of cellular redox status Trx/TXNIP complex, endoplasmic reticulum stress and the pathogenesis of diseases such as type 2 diabetes. Finally, we have provided data on NLRP3 inflammasome, as a critical regulator involved in the pathogenesis of obesity and cardiovascular diseases.
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Affiliation(s)
- Amna Abderrazak
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing - IBPS, F-75005 Paris, France; CNRS-UMR 8256, F-75005 Paris, France; Inserm U1164, F-75005 Paris, France
| | - Tatiana Syrovets
- Institute of Pharmacology of Natural Products & Clinical Pharmacology, Ulm University, D-89081 Ulm, Germany
| | - Dominique Couchie
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing - IBPS, F-75005 Paris, France; CNRS-UMR 8256, F-75005 Paris, France; Inserm U1164, F-75005 Paris, France
| | - Khadija El Hadri
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing - IBPS, F-75005 Paris, France; CNRS-UMR 8256, F-75005 Paris, France; Inserm U1164, F-75005 Paris, France
| | - Bertrand Friguet
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing - IBPS, F-75005 Paris, France; CNRS-UMR 8256, F-75005 Paris, France; Inserm U1164, F-75005 Paris, France
| | - Thomas Simmet
- Institute of Pharmacology of Natural Products & Clinical Pharmacology, Ulm University, D-89081 Ulm, Germany
| | - Mustapha Rouis
- Sorbonne Universités, UPMC Univ Paris 06, UMR 8256, Biological Adaptation and Ageing - IBPS, F-75005 Paris, France; CNRS-UMR 8256, F-75005 Paris, France; Inserm U1164, F-75005 Paris, France.
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594
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Theodoraki A, Hu Y, Poopalasundaram S, Oosterhof A, Guimond SE, Disterer P, Khoo B, Hauge-Evans AC, Jones PM, Turnbull JE, van Kuppevelt TH, Bouloux PM. Distinct patterns of heparan sulphate in pancreatic islets suggest novel roles in paracrine islet regulation. Mol Cell Endocrinol 2015; 399:296-310. [PMID: 25224485 DOI: 10.1016/j.mce.2014.09.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 08/18/2014] [Accepted: 09/10/2014] [Indexed: 11/29/2022]
Abstract
Heparan sulphate proteoglycans (HSPGs) exist in pancreatic beta cells, and HS seems to modulate important interactions in the islet microenvironment. However, the intra-islet structures of HS in health or altered glucose homeostasis are currently unknown. Here we show that distinct spatial distribution of HS motifs is present in islets in the adult, that intra-islet HS motifs are mostly conserved between rodents and humans, and that HS is abundant in glucagon producing islet alpha cells. In beta cells HS is characterised by 2-O, 6-O and N-sulphated moieties, whereas HS in alpha cells is N-acetylated, N-, and 2-O sulphated and low in 6-O groups. Differential expression of three HS modifying genes in alpha and beta cells was observed and may account for the different HS patterns. Furthermore, we found that FGF1 and FGF2 were present in alpha cells, whereas functional FGFRs exist in beta cells, but not in the alpha cell line aTC1-6, or in primary alpha cells in islets. FGF1 induced signalling was dependent on 2-O, and 6-O HS sulphation in beta cells, and HS desulphation reduced beta cell proliferation and potentiated oxidant induced apoptosis. In leptin resistant animals and in islets from streptozotocin treated rats there was a reduction in alpha cell HS expression. These data demonstrate the distinct HS expression patterns in alpha and beta islet cells and propose a novel role for alpha cells as a source of paracrine FGF ligands to neighbouring beta cells with specific cell-associated HS domains mediating the activation and diffusion of paracrine ligands.
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Affiliation(s)
| | - Youli Hu
- Centre for Neuroendocrinology, Royal Free Campus, UCL, London NW3 2QG, UK
| | | | - Arie Oosterhof
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands
| | - Scott E Guimond
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZE, UK
| | - Petra Disterer
- Centre for Neuroendocrinology, Royal Free Campus, UCL, London NW3 2QG, UK
| | - Bernard Khoo
- Centre for Neuroendocrinology, Royal Free Campus, UCL, London NW3 2QG, UK
| | - Astrid C Hauge-Evans
- Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Peter M Jones
- Diabetes and Nutritional Sciences Division, School of Medicine, King's College London, Guy's Campus, London SE1 1UL, UK
| | - Jeremy E Turnbull
- Institute of Integrative Biology, University of Liverpool, Liverpool L69 7ZE, UK
| | - Toin H van Kuppevelt
- Department of Biochemistry, Nijmegen Centre for Molecular Life Sciences, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands
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595
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Fortin JS, Benoit-Biancamano MO. Wildlife sequences of islet amyloid polypeptide (IAPP) identify critical species variants for fibrillization. Amyloid 2015; 22:194-202. [PMID: 26300107 DOI: 10.3109/13506129.2015.1070824] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Amyloid can be detected in the islets of Langerhans in a majority of type 2 diabetic patients. These deposits have been associated with β-cell death, thereby furthering diabetes progression. Islet amyloid polypeptide (IAPP) amyloidogenicity is quite variable among animal species, and studying this variability could further our understanding of the mechanisms involved in the aggregation process. Thus, the general aim of this study was to identify IAPP isoforms in different animal species and characterize their propensity to form fibrillar aggregates. A library of 23 peptides (fragment 8-32) was designed to study the amyloid formation using in silico analysis and in vitro assays. Amyloid formation was impeded when the NFLVH motif found in segment 8-20 was substituted by DFLGR or KFLIR segments. A 29P, 14K and 18R substitution were often present in non-amyloidogenic sequences. Non-amyloidogenic sequences were obtained from Leontopithecus rosalia, Tursiops truncatus and Vicugna pacos. Fragment peptides from 34 species were amyloidogenic. To conclude, this project advances our knowledge on the comparative pathogenesis of amyloidosis in type II diabetes. It is conceivable that the additional information gained may help point towards new therapeutic strategies for diabetes patients.
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Affiliation(s)
- Jessica S Fortin
- a Département de Pathologie et de Microbiologie, Faculté de Médecine Vétérinaire , Université de Montréal , Saint-Hyacinthe , Quebec , Canada
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596
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Gao M, Winter R. The Effects of Lipid Membranes, Crowding and Osmolytes on the Aggregation, and Fibrillation Propensity of Human IAPP. J Diabetes Res 2015; 2015:849017. [PMID: 26582333 PMCID: PMC4637101 DOI: 10.1155/2015/849017] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/16/2015] [Indexed: 12/13/2022] Open
Abstract
Type 2 diabetes mellitus (T2DM) is an age-related and metabolic disease. Its development is hallmarked, among others, by the dysfunction and degeneration of β-cells of the pancreatic islets of Langerhans. The major pathological characteristic thereby is the formation of extracellular amyloid deposits consisting of the islet amyloid polypeptide (IAPP). The process of human IAPP (hIAPP) self-association, and the intermediate structures formed as well as the interaction of hIAPP with membrane systems seem to be, at least to a major extent, responsible for the cytotoxicity. Here we present a summary and comparison of the amyloidogenic propensities of hIAPP in bulk solution and in the presence of various neutral and charged lipid bilayer systems as well as biological membranes. We also discuss the cellular effects of macromolecular crowding and osmolytes on the aggregation pathway of hIAPP. Understanding the influence of different cellular factors on hIAPP aggregation will provide more insight into the onset of T2DM and help to develop novel therapeutic strategies.
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Affiliation(s)
- Mimi Gao
- Physical Chemistry I-Biophysical Chemistry, Department of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn Street 6, 44227 Dortmund, Germany
| | - Roland Winter
- Physical Chemistry I-Biophysical Chemistry, Department of Chemistry and Chemical Biology, TU Dortmund, Otto-Hahn Street 6, 44227 Dortmund, Germany
- *Roland Winter:
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597
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Nguyen PT, Andraka N, De Carufel CA, Bourgault S. Mechanistic Contributions of Biological Cofactors in Islet Amyloid Polypeptide Amyloidogenesis. J Diabetes Res 2015; 2015:515307. [PMID: 26576436 PMCID: PMC4630397 DOI: 10.1155/2015/515307] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Revised: 01/26/2015] [Accepted: 02/09/2015] [Indexed: 01/24/2023] Open
Abstract
Type II diabetes mellitus is associated with the deposition of fibrillar aggregates in pancreatic islets. The major protein component of islet amyloids is the glucomodulatory hormone islet amyloid polypeptide (IAPP). Islet amyloid fibrils are virtually always associated with several biomolecules, including apolipoprotein E, metals, glycosaminoglycans, and various lipids. IAPP amyloidogenesis has been originally perceived as a self-assembly homogeneous process in which the inherent aggregation propensity of the peptide and its local concentration constitute the major driving forces to fibrillization. However, over the last two decades, numerous studies have shown a prominent role of amyloid cofactors in IAPP fibrillogenesis associated with the etiology of type II diabetes. It is increasingly evident that the biochemical microenvironment in which IAPP amyloid formation occurs and the interactions of the polypeptide with various biomolecules not only modulate the rate and extent of aggregation, but could also remodel the amyloidogenesis process as well as the structure, toxicity, and stability of the resulting fibrils.
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Affiliation(s)
- Phuong Trang Nguyen
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Nagore Andraka
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- Biophysics Unit (CSIC, UPV/EHU) and Department of Biochemistry and Molecular Biology, Faculty of Science and Technology, University of the Basque Country, 48080 Bilbao, Spain
| | - Carole Anne De Carufel
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
| | - Steve Bourgault
- Department of Chemistry, Pharmaqam, University of Quebec in Montreal, Montreal, QC, Canada H3C 3P8
- Quebec Network for Research on Protein Function, Structure, and Engineering (PROTEO), Canada
- *Steve Bourgault:
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598
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Patil SM, Alexandrescu AT. Charge-Based Inhibitors of Amylin Fibrillization and Toxicity. J Diabetes Res 2015; 2015:946037. [PMID: 26576438 PMCID: PMC4630399 DOI: 10.1155/2015/946037] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Accepted: 12/12/2014] [Indexed: 02/01/2023] Open
Abstract
To test the hypothesis that electrostatic repulsion is an important force opposing amyloid fibril assembly, we designed peptides that substitute strings of positively or negatively charged residues into the sequence of the amyloidogenic hormone amylin, which contributes to type 2 diabetes pathology. Arg-1 and Arg-2 substitute four positively charged arginines for segments that in structural models of amylin fibrils form the end of strand β1 and the beginning of strand β2, respectively. Mem-T substitutes negatively charged aspartates for the peptide segment with the largest avidity for membranes. All three charge-loaded peptides fibrillize poorly on their own and inhibit fibril elongation of WT-amylin at physiological ionic strength. The inhibition of WT-amylin fibril elongation rates is salt-dependent indicating that the analogs act through electrostatic interactions. Arg-1 protects against WT-amylin cytotoxicity towards a MIN6 mouse model of pancreatic β-cells, and Arg-2 protects at higher concentrations, whereas Mem-T has no effect. The most effective variant, Arg-1, inhibits WT-amylin fibril elongation rates with an IC50 of ~1 µM and cytotoxicity with an IC50 of ~50 µM, comparable to other types of fibrillization inhibitors reported in the literature. Taken together, these results suggest that electrostatic interactions can be exploited to develop new types of inhibitors of amyloid fibrillization and toxicity.
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Affiliation(s)
- Sharadrao M. Patil
- Department of Molecular and Cell Biology, University of Connecticut, 91 N. Eagleville Road, Storrs, CT 06269-3125, USA
| | - Andrei T. Alexandrescu
- Department of Molecular and Cell Biology, University of Connecticut, 91 N. Eagleville Road, Storrs, CT 06269-3125, USA
- *Andrei T. Alexandrescu:
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599
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Singh S, Trikha S, Bhowmick DC, Sarkar AA, Jeremic AM. Role of Cholesterol and Phospholipids in Amylin Misfolding, Aggregation and Etiology of Islet Amyloidosis. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 855:95-116. [PMID: 26149927 DOI: 10.1007/978-3-319-17344-3_4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Amyloidosis is a biological event in which proteins undergo structural transitions from soluble monomers and oligomers to insoluble fibrillar aggregates that are often toxic to cells. Exactly how amyloid proteins, such as the pancreatic hormone amylin, aggregate and kill cells is still unclear. Islet amyloid polypeptide, or amylin, is a recently discovered hormone that is stored and co-released with insulin from pancreatic islet β-cells. The pathology of type 2 diabetes mellitus (T2DM) is characterized by an excessive extracellular and intracellular accumulation of toxic amylin species, soluble oligomers and insoluble fibrils, in islets, eventually leading to β-cell loss. Obesity and elevated serum cholesterol levels are additional risk factors implicated in the development of T2DM. Because the homeostatic balance between cholesterol synthesis and uptake is lost in diabetics, and amylin aggregation is a hallmark of T2DM, this chapter focuses on the biophysical and cell biology studies exploring molecular mechanisms by which cholesterol and phospholipids modulate secondary structure, folding and aggregation of human amylin and other amyloid proteins on membranes and in cells. Amylin turnover and toxicity in pancreatic cells and the regulatory role of cholesterol in these processes are also discussed.
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Affiliation(s)
- Sanghamitra Singh
- Department of Biological Sciences, The George Washington University, 2023 G Street NW, Washington, DC, 20052, USA
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600
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Westermark P. Localized Amyloidoses and Amyloidoses Associated with Aging Outside the Central Nervous System. CURRENT CLINICAL PATHOLOGY 2015. [DOI: 10.1007/978-3-319-19294-9_7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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