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Rishisree A, Mallory B, Elena K, Teodora J, Gordana Z, Katarina Š, Aleksandar J. Pomegranate peel, chokeberry leaves and Ironwort extract as novel natural inhibitors of amylin aggregation and cellular toxicity in pancreatic β cells. Biophys Chem 2024; 304:107130. [PMID: 37952497 PMCID: PMC10841580 DOI: 10.1016/j.bpc.2023.107130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 10/27/2023] [Accepted: 10/28/2023] [Indexed: 11/14/2023]
Abstract
Impeding or reducing human amylin aggregation and/or its toxicity can be key to preventing pancreatic islet amyloidosis and β-cell loss in patients with Type 2 Diabetes Mellitus (T2DM). Here, Punica granatum (pomegranate) peel, Sideritis raeseri (ironwort) and Aronia melanocarpa (chokeberry) leaf extracts, were tested for their novel anti-aggregative and antitoxic properties in human amylin (hIAPP) treated rat pancreatic insulinoma (INS) cells. The protein aggregation (Th-T) assay revealed an inhibitory trend of all three plant extracts against amylin aggregates. In agreement with this finding, pomegranate peel and ironwort extracts effectively prevented the transition of hIAPP from disordered, random coil structures into aggregation prone β-sheet enriched molecular assemblies, revealed by CD spectroscopy. Consistent with their anti-aggregative action, all three extracts prevented, to various degrees, reactive oxygen species (ROS) accumulation, mitochondrial stress, and, ultimately, apoptosis of INS cells. Collectively, the results from this study demonstrate effectiveness of natural products to halt hIAPP aggregation, redox stress, and toxicity, which could be exploited as novel therapeutics against amylin-derived islet amyloidosis and β-cell stress in T2DM.
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Affiliation(s)
- Achanta Rishisree
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Brayer Mallory
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Karnaukhova Elena
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
| | - Jankovic Teodora
- Institute for Medicinal Plant Research "Dr. Josif Pančić", 11000 Belgrade, Serbia
| | - Zdunić Gordana
- Institute for Medicinal Plant Research "Dr. Josif Pančić", 11000 Belgrade, Serbia
| | - Šavikin Katarina
- Institute for Medicinal Plant Research "Dr. Josif Pančić", 11000 Belgrade, Serbia
| | - Jeremic Aleksandar
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA.
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Meleleo D, Cibelli G, Valenzano A, Mastrodonato M, Mallamaci R. The Effect of Calcium Ions on hIAPP Channel Activity: Possible Implications in T2DM. MEMBRANES 2023; 13:878. [PMID: 37999364 PMCID: PMC10673357 DOI: 10.3390/membranes13110878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 11/07/2023] [Accepted: 11/07/2023] [Indexed: 11/25/2023]
Abstract
The calcium ion (Ca2+) has been linked to type 2 diabetes mellitus (T2DM), although the role of Ca2+ in this disorder is the subject of intense investigation. Serum Ca2+ dyshomeostasis is associated with the development of insulin resistance, reduced insulin sensitivity, and impaired glucose tolerance. However, the molecular mechanisms involving Ca2+ ions in pancreatic β-cell loss and subsequently in T2DM remain poorly understood. Implicated in the decline in β-cell functions are aggregates of human islet amyloid polypeptide (hIAPP), a small peptide secreted by β-cells that shows a strong tendency to self-aggregate into β-sheet-rich aggregates that evolve toward the formation of amyloid deposits and mature fibrils. The soluble oligomers of hIAPP can permeabilize the cell membrane by interacting with bilayer lipids. Our study aimed to evaluate the effect of Ca2+ on the ability of the peptide to incorporate and form ion channels in zwitterionic planar lipid membranes (PLMs) composed of palmitoyl-oleoyl-phosphatidylcholine (POPC) and on the aggregation process of hIAPP molecules in solution. Our results may help to clarify the link between Ca2+ ions, hIAPP peptide, and consequently the pathophysiology of T2DM.
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Affiliation(s)
- Daniela Meleleo
- Department of Science of Agriculture, Food, Natural Resources and Engineering, University of Foggia, 71122 Foggia, Italy
| | - Giuseppe Cibelli
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (G.C.); (A.V.)
| | - Anna Valenzano
- Department of Clinical and Experimental Medicine, University of Foggia, 71122 Foggia, Italy; (G.C.); (A.V.)
| | - Maria Mastrodonato
- Department of Biosciences, Biotechnologies and Environment, University of Bari “Aldo Moro”, 70125 Bari, Italy; (M.M.); (R.M.)
| | - Rosanna Mallamaci
- Department of Biosciences, Biotechnologies and Environment, University of Bari “Aldo Moro”, 70125 Bari, Italy; (M.M.); (R.M.)
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Sevcuka A, White K, Terry C. Factors That Contribute to hIAPP Amyloidosis in Type 2 Diabetes Mellitus. Life (Basel) 2022; 12:life12040583. [PMID: 35455074 PMCID: PMC9025880 DOI: 10.3390/life12040583] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 04/01/2022] [Accepted: 04/12/2022] [Indexed: 12/24/2022] Open
Abstract
Cases of Type 2 Diabetes Mellitus (T2DM) are increasing at an alarming rate due to the rise in obesity, sedentary lifestyles, glucose-rich diets and other factors. Numerous studies have increasingly illustrated the pivotal role that human islet amyloid polypeptide (hIAPP) plays in the pathology of T2DM through damage and subsequent loss of pancreatic β-cell mass. HIAPP can misfold and form amyloid fibrils which are preceded by pre-fibrillar oligomers and monomers, all of which have been linked, to a certain extent, to β-cell cytotoxicity through a range of proposed mechanisms. This review provides an up-to-date summary of recent progress in the field, highlighting factors that contribute to hIAPP misfolding and aggregation such as hIAPP protein concentration, cell stress, molecular chaperones, the immune system response and cross-seeding with other amyloidogenic proteins. Understanding the structure of hIAPP and how these factors affect amyloid formation will help us better understand how hIAPP misfolds and aggregates and, importantly, help identify potential therapeutic targets for inhibiting amyloidosis so alternate and more effective treatments for T2DM can be developed.
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Nguyen TH, Nguyen PH, Ngo ST, Derreumaux P. Effect of Cholesterol Molecules on Aβ1-42 Wild-Type and Mutants Trimers. Molecules 2022; 27:molecules27041395. [PMID: 35209177 PMCID: PMC8879133 DOI: 10.3390/molecules27041395] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 02/14/2022] [Accepted: 02/15/2022] [Indexed: 12/04/2022] Open
Abstract
Alzheimer’s disease displays aggregates of the amyloid-beta (Aβ) peptide in the brain, and there is increasing evidence that cholesterol may contribute to the pathogenesis of the disease. Though many experimental and theoretical studies have focused on the interactions of Aβ oligomers with membrane models containing cholesterol, an understanding of the effect of free cholesterol on small Aβ42 oligomers is not fully established. To address this question, we report on replica exchange with a solute tempering simulation of an Aβ42 trimer with cholesterol and compare it with a previous replica exchange molecular dynamics simulation. We show that the binding hot spots of cholesterol are rather complex, involving hydrophobic residues L17–F20 and L30–M35 with a non-negligible contribution of loop residues D22–K28 and N-terminus residues. We also examine the effects of cholesterol on the trimers of the disease-causing A21G and disease-protective A2T mutations by molecular dynamics simulations. We show that these two mutations moderately impact cholesterol-binding modes. In our REST2 simulations, we find that cholesterol is rarely inserted into aggregates but rather attached as dimers and trimers at the surface of Aβ42 oligomers. We propose that cholesterol acts as a glue to speed up the formation of larger aggregates; this provides a mechanistic link between cholesterol and Alzheimer’s disease.
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Affiliation(s)
- Trung Hai Nguyen
- Laboratory of Theoretical and Computational Biophysics, Ton Duc Thang University, Ho Chi Minh City, Vietnam; (T.H.N.); (S.T.N.)
- Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| | - Phuong H. Nguyen
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université de Paris, 13 rue Pierre et Marie Curie, 75005 Paris, France;
- Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild, PSL Research University, 75005 Paris, France
| | - Son Tung Ngo
- Laboratory of Theoretical and Computational Biophysics, Ton Duc Thang University, Ho Chi Minh City, Vietnam; (T.H.N.); (S.T.N.)
- Faculty of Applied Sciences, Ton Duc Thang University, Ho Chi Minh City, Vietnam
| | - Philippe Derreumaux
- Laboratoire de Biochimie Théorique, UPR 9080 CNRS, Université de Paris, 13 rue Pierre et Marie Curie, 75005 Paris, France;
- Institut de Biologie Physico-Chimique, Fondation Edmond de Rothschild, PSL Research University, 75005 Paris, France
- Institut Universitaire de France (IUF), 75005 Paris, France
- Correspondence:
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Molecular Mechanisms of Amylin Turnover, Misfolding and Toxicity in the Pancreas. Molecules 2022; 27:molecules27031021. [PMID: 35164285 PMCID: PMC8838401 DOI: 10.3390/molecules27031021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 01/24/2022] [Accepted: 01/29/2022] [Indexed: 12/13/2022] Open
Abstract
Amyloidosis is a common pathological event in which proteins self-assemble into misfolded soluble and insoluble molecular forms, oligomers and fibrils that are often toxic to cells. Notably, aggregation-prone human islet amyloid polypeptide (hIAPP), or amylin, is a pancreatic hormone linked to islet β-cells demise in diabetics. The unifying mechanism by which amyloid proteins, including hIAPP, aggregate and kill cells is still matter of debate. The pathology of type-2 diabetes mellitus (T2DM) is characterized by extracellular and intracellular accumulation of toxic hIAPP species, soluble oligomers and insoluble fibrils in pancreatic human islets, eventually leading to loss of β-cell mass. This review focuses on molecular, biochemical and cell-biology studies exploring molecular mechanisms of hIAPP synthesis, trafficking and degradation in the pancreas. In addition to hIAPP turnover, the dynamics and the mechanisms of IAPP–membrane interactions; hIAPP aggregation and toxicity in vitro and in situ; and the regulatory role of diabetic factors, such as lipids and cholesterol, in these processes are also discussed.
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Pathak BK, Dey S, Mozumder S, Sengupta J. The role of membranes in function and dysfunction of intrinsically disordered amyloidogenic proteins. ADVANCES IN PROTEIN CHEMISTRY AND STRUCTURAL BIOLOGY 2021; 128:397-434. [PMID: 35034725 DOI: 10.1016/bs.apcsb.2021.08.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Membrane-protein interactions play a major role in human physiology as well as in diseases pathology. Interaction of a protein with the membrane was previously thought to be dependent on well-defined three-dimensional structure of the protein. In recent decades, however, it has become evident that a large fraction of the proteome, particularly in eukaryotes, stays disordered in solution and these proteins are termed as intrinsically disordered proteins (IDPs). Also, a vast majority of human proteomes have been reported to contain substantially long disordered regions, called intrinsically disordered regions (IDRs), in addition to the structurally ordered regions. IDPs exist in an ensemble of conformations and the conformational flexibility enables IDPs to achieve functional diversity. IDPs (and IDRs) are found to be important players in cell signaling, where biological membranes act as anchors for signaling cascades. Therefore, IDPs modulate the membrane architectures, at the same time membrane composition also affects the binding of IDPs. Because of intrinsic disorders, misfolding of IDPs often leads to formation of oligomers, protofibrils and mature fibrils through progressive self-association. Accumulation of amyloid-like aggregates of some of the IDPs is a known causative agent for numerous diseases. In this chapter we highlight recent advances in understanding membrane interactions of some of the intrinsically disordered proteins involved in the pathogenesis of human diseases.
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Affiliation(s)
- Bani Kumar Pathak
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sandip Dey
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India
| | - Sukanya Mozumder
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Jayati Sengupta
- Structural Biology and Bioinformatics Division, CSIR-Indian Institute of Chemical Biology, Jadavpur, Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India.
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Marmentini C, Branco RCS, Boschero AC, Kurauti MA. Islet amyloid toxicity: From genesis to counteracting mechanisms. J Cell Physiol 2021; 237:1119-1142. [PMID: 34636428 DOI: 10.1002/jcp.30600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 09/09/2021] [Accepted: 10/01/2021] [Indexed: 11/11/2022]
Abstract
Islet amyloid polypeptide (IAPP or amylin) is a hormone co-secreted with insulin by pancreatic β-cells and is the major component of islet amyloid. Islet amyloid is found in the pancreas of patients with type 2 diabetes (T2D) and may be involved in β-cell dysfunction and death, observed in this disease. Thus, investigating the aspects related to amyloid formation is relevant to the development of strategies towards β-cell protection. In this sense, IAPP misprocessing, IAPP overproduction, and disturbances in intra- and extracellular environments seem to be decisive for IAPP to form islet amyloid. Islet amyloid toxicity in β-cells may be triggered in intra- and/or extracellular sites by membrane damage, endoplasmic reticulum stress, autophagy disruption, mitochondrial dysfunction, inflammation, and apoptosis. Importantly, different approaches have been suggested to prevent islet amyloid cytotoxicity, from inhibition of IAPP aggregation to attenuation of cell death mechanisms. Such approaches have improved β-cell function and prevented the development of hyperglycemia in animals. Therefore, counteracting islet amyloid may be a promising therapy for T2D treatment.
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Affiliation(s)
- Carine Marmentini
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Brazil
| | - Renato C S Branco
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Brazil
| | - Antonio C Boschero
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Brazil
| | - Mirian A Kurauti
- Laboratory of Endocrine Pancreas and Metabolism, Obesity and Comorbidities Research Center (OCRC), University of Campinas (UNICAMP), Campinas, Brazil.,Department of Physiological Sciences, Biological Sciences Center, State University of Maringa (UEM), Maringa, Brazil
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Living with the enemy: from protein-misfolding pathologies we know, to those we want to know. Ageing Res Rev 2021; 70:101391. [PMID: 34119687 DOI: 10.1016/j.arr.2021.101391] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 04/19/2021] [Accepted: 06/09/2021] [Indexed: 12/12/2022]
Abstract
Conformational diseases are caused by the aggregation of misfolded proteins. The risk for such pathologies develops years before clinical symptoms appear, and is higher in people with alpha-1 antitrypsin (AAT) polymorphisms. Thousands of people with alpha-1 antitrypsin deficiency (AATD) are underdiagnosed. Enemy-aggregating proteins may reside in these underdiagnosed AATD patients for many years before a pathology for AATD fully develops. In this perspective review, we hypothesize that the AAT protein could exert a new and previously unconsidered biological effect as an endogenous metal ion chelator that plays a significant role in essential metal ion homeostasis. In this respect, AAT polymorphism may cause an imbalance of metal ions, which could be correlated with the aggregation of amylin, tau, amyloid beta, and alpha synuclein proteins in type 2 diabetes mellitus (T2DM), Alzheimer's and Parkinson's diseases, respectively.
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Tan Q, Liu H, Duan M, Huo S. Interplay between human islet amyloid polypeptide aggregates and micro-heterogeneous membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183691. [PMID: 34224702 DOI: 10.1016/j.bbamem.2021.183691] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 10/20/2022]
Abstract
Human islet amyloid polypeptides (hIAPP) aggregate into amyloid deposits in the pancreatic islets of Langerhans, contributing to the loss of β-cells of patients with type 2 diabetes. Despite extensive studies of membrane disruption associated with hIAPP aggregates, the molecular details regarding the complex interplay between hIAPP aggregates and raft-containing membranes are still very limited. Using all-atom molecular dynamics simulations, we investigate the impact of hIAPP aggregate insertion on lipid segregation. We have found that the domain separation of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) is enhanced upon hIAPP membrane permeabilization in the absence of cholesterol, while within our simulation timescale, we cannot provide definitive evidence regarding the impact of hIAPP insertion on domain segregation in the ternary mixture (DOPC/DPPC/cholesterol). When the lipid domains are perturbed, their restoration occurs rapidly and spontaneously in the presence of hIAPP aggregates. hIAPP insertion affects membrane thickness in its immediate surroundings. On average, hIAPP causes the fluidity of lipids to increase and even cholesterol shows enhanced diffusivity. The acyl chain packing of the lipids near hIAPP is disrupted as compared to that further away from it. Cholesterol not only modulates membrane mobility and ordering but also hIAPP aggregates' structure and relative orientation to the membrane. Our investigations on the interaction between hIAPP aggregates and raft-containing membranes could lead to a better understanding of the mechanisms of amyloid cytotoxicity.
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Affiliation(s)
- Qingzhe Tan
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA
| | - Hanzhong Liu
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA
| | - Mojie Duan
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA; Key Laboratory of Magnetic Resonance in Biological Systems, National Center for Magnetic Resonance in Wuhan, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Shuanghong Huo
- Gustaf H. Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA.
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Martínez-Navarro I, Díaz-Molina R, Pulido-Capiz A, Mas-Oliva J, Luna-Reyes I, Rodríguez-Velázquez E, Rivero IA, Ramos-Ibarra MA, Alatorre-Meda M, García-González V. Lipid Modulation in the Formation of β-Sheet Structures. Implications for De Novo Design of Human Islet Amyloid Polypeptide and the Impact on β-Cell Homeostasis. Biomolecules 2020; 10:biom10091201. [PMID: 32824918 PMCID: PMC7563882 DOI: 10.3390/biom10091201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Revised: 08/03/2020] [Accepted: 08/04/2020] [Indexed: 12/25/2022] Open
Abstract
Human islet amyloid polypeptide (hIAPP) corresponds to a 37-residue hormone present in insulin granules that maintains a high propensity to form β-sheet structures during co-secretion with insulin. Previously, employing a biomimetic approach, we proposed a panel of optimized IAPP sequences with only one residue substitution that shows the capability to reduce amyloidogenesis. Taking into account that specific membrane lipids have been considered as a key factor in the induction of cytotoxicity, in this study, following the same design strategy, we characterize the effect of a series of lipids upon several polypeptide domains that show the highest aggregation propensity. The characterization of the C-native segment of hIAPP (residues F23-Y37), together with novel variants F23R and I26A allowed us to demonstrate an effect upon the formation of β-sheet structures. Our results suggest that zwitterionic phospholipids promote adsorption of the C-native segments at the lipid-interface and β-sheet formation with the exception of the F23R variant. Moreover, the presence of cholesterol did not modify this behavior, and the β-sheet structural transitions were not registered when the N-terminal domain of hIAPP (K1-S20) was characterized. Considering that insulin granules are enriched in phosphatidylserine (PS), the property of lipid vesicles containing negatively charged lipids was also evaluated. We found that these types of lipids promote β-sheet conformational transitions in both the C-native segment and the new variants. Furthermore, these PS/peptides arrangements are internalized in Langerhans islet β-cells, localized in the endoplasmic reticulum, and trigger critical pathways such as unfolded protein response (UPR), affecting insulin secretion. Since this phenomenon was associated with the presence of cytotoxicity on Langerhans islet β-cells, it can be concluded that the anionic lipid environment and degree of solvation are critical conditions for the stability of segments with the propensity to form β-sheet structures, a situation that will eventually affect the structural characteristics and stability of IAPP within insulin granules, thus modifying the insulin secretion.
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Affiliation(s)
- Israel Martínez-Navarro
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Raúl Díaz-Molina
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
| | - Angel Pulido-Capiz
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Laboratorio de Biología Molecular, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico
| | - Jaime Mas-Oliva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Ismael Luna-Reyes
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ciudad de Mexico 04510, Mexico; (J.M.-O.); (I.L.-R.)
| | - Eustolia Rodríguez-Velázquez
- Facultad de Odontología, Universidad Autónoma de Baja California, Tijuana 22390, Mexico;
- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico
| | - Ignacio A. Rivero
- Tecnológico Nacional de México/Instituto Tecnológico de Tijuana, Centro de Graduados e Investigación en Química, Tijuana 22510, Baja California, Mexico;
| | - Marco A. Ramos-Ibarra
- Facultad de Ciencias Químicas e Ingeniería, Universidad Autónoma de Baja California, Tijuana 22390, Baja California, Mexico;
| | - Manuel Alatorre-Meda
- Cátedras CONACyT- Tecnológico Nacional de México/I.T. Tijuana, Centro de Graduados e Investigación en Química-Grupo de Biomateriales y Nanomedicina, Tijuana 22510, Mexico;
| | - Victor García-González
- Departamento de Bioquímica, Facultad de Medicina Mexicali, Universidad Autónoma de Baja California, Mexicali 21000, Baja California, Mexico; (I.M.-N.); (R.D.-M.); (A.P.-C.)
- Correspondence: ; Tel.: +52-68-6557-1622
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Liu Y, Zhang D, Zhang Y, Tang Y, Xu L, He H, Wu J, Zheng J. Molecular Dynamics Simulations of Cholesterol Effects on the Interaction of hIAPP with Lipid Bilayer. J Phys Chem B 2020; 124:7830-7841. [DOI: 10.1021/acs.jpcb.0c05742] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Yonglan Liu
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Dong Zhang
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Yanxian Zhang
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Yijing Tang
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44325, United States
| | - Lijian Xu
- Hunan Key Laboratory of Biomedical Nanomaterials and Devices College of Life Science and Chemistry, Hunan University of Technology, Zhuzhou 412007, P. R. China
| | - Huacheng He
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou, Zhejiang 325027, P. R. China
| | - Jiang Wu
- School of Pharmaceutical Sciences, Wenzhou Medical University, Wenzhou, Zhejiang 325035, P. R. China
| | - Jie Zheng
- Department of Chemical, Biomolecular, and Corrosion Engineering, The University of Akron, Akron, Ohio 44325, United States
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Kumar AP, Lee S, Lukman S. Computational and Experimental Approaches to Design Inhibitors of Amylin Aggregation. Curr Drug Targets 2019; 20:1680-1694. [DOI: 10.2174/1389450120666190719164316] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/04/2019] [Accepted: 07/05/2019] [Indexed: 01/21/2023]
Abstract
Amylin is a neuroendocrine peptide hormone secreted by pancreatic ß-cells; however,
amylin is toxic to ß-cells when it is aggregated in type 2 diabetes mellitus (T2DM). It is important to
understand amylin’s structures and aggregation mechanism for the discovery and design of effective
drugs to inhibit amylin aggregation. In this review, we investigated experimental and computational
studies on amylin structures and inhibitors. Our review provides some novel insights into amylin, particularly
for the design of its aggregation inhibitors to treat T2DM. We detailed the potential inhibitors
that have been studied hitherto and highlighted the neglected need to consider different amylin attributes
that depend on the presence/absence of physiologically relevant conditions, such as membranes.
These conditions and the experimental methods can greatly influence the results of studies on amylininhibitor
complexes. Text-mining over 3,000 amylin-related PubMed abstracts suggests the combined
therapeutic potential of amylin with leptin and glucagon-like peptide-1, which are two key hormones
in obesity. The results also suggest that targeting amylin aggregation can contribute to therapeutic efforts
for Alzheimer’s disease (AD). Therefore, we have also reviewed the role of amylin in other conditions
including obesity and AD. Finally, we provided insights for designing inhibitors of different
types (small molecules, proteins, peptides/mimetics, metal ions) to inhibit amylin aggregation.
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Affiliation(s)
- Ammu Prasanna Kumar
- Department of Chemistry, College of Arts and Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Sungmun Lee
- Department of Biomedical Engineering and Healthcare Engineering Innovation Center, College of Engineering, Khalifa University, Abu Dhabi, United Arab Emirates
| | - Suryani Lukman
- Department of Chemistry, College of Arts and Sciences, Khalifa University, Abu Dhabi, United Arab Emirates
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Owen MC, Gnutt D, Gao M, Wärmländer SKTS, Jarvet J, Gräslund A, Winter R, Ebbinghaus S, Strodel B. Effects of in vivo conditions on amyloid aggregation. Chem Soc Rev 2019; 48:3946-3996. [PMID: 31192324 DOI: 10.1039/c8cs00034d] [Citation(s) in RCA: 123] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
One of the grand challenges of biophysical chemistry is to understand the principles that govern protein misfolding and aggregation, which is a highly complex process that is sensitive to initial conditions, operates on a huge range of length- and timescales, and has products that range from protein dimers to macroscopic amyloid fibrils. Aberrant aggregation is associated with more than 25 diseases, which include Alzheimer's, Parkinson's, Huntington's, and type II diabetes. Amyloid aggregation has been extensively studied in the test tube, therefore under conditions that are far from physiological relevance. Hence, there is dire need to extend these investigations to in vivo conditions where amyloid formation is affected by a myriad of biochemical interactions. As a hallmark of neurodegenerative diseases, these interactions need to be understood in detail to develop novel therapeutic interventions, as millions of people globally suffer from neurodegenerative disorders and type II diabetes. The aim of this review is to document the progress in the research on amyloid formation from a physicochemical perspective with a special focus on the physiological factors influencing the aggregation of the amyloid-β peptide, the islet amyloid polypeptide, α-synuclein, and the hungingtin protein.
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Affiliation(s)
- Michael C Owen
- CEITEC - Central European Institute of Technology, Masaryk University, Kamenice 753/5, Brno 625 00, Czech Republic
| | - David Gnutt
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, 38106 Braunschweig, Germany and Lead Discovery Wuppertal, Bayer AG, 42096 Wuppertal, Germany
| | - Mimi Gao
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Str. 4a, 44227 Dortmund, Germany and Sanofi-Aventis Deutschland GmbH, R&D, Industriepark Höchst, 65926 Frankfurt, Germany
| | - Sebastian K T S Wärmländer
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Jüri Jarvet
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Astrid Gräslund
- Department of Biochemistry and Biophysics, Stockholm University, Svante Arrhenius väg 16C, 106 91 Stockholm, Sweden
| | - Roland Winter
- Faculty of Chemistry and Chemical Biology, TU Dortmund University, Otto-Hahn Str. 4a, 44227 Dortmund, Germany
| | - Simon Ebbinghaus
- Institute of Physical and Theoretical Chemistry, TU Braunschweig, Rebenring 56, 38106 Braunschweig, Germany
| | - Birgit Strodel
- Institute of Complex Systems: Structural Biochemistry, Forschungszentrum Jülich, 42525 Jülich, Germany. and Institute of Theoretical and Computational Chemistry, Heinrich Heine University Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf, Germany
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14
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Kever L, Cherezova A, Zenin V, Negulyaev Y, Komissarchik Y, Semenova S. Downregulation of TRPV6 channel activity by cholesterol depletion in Jurkat T cell line. Cell Biol Int 2019; 43:965-975. [DOI: 10.1002/cbin.11185] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 05/21/2019] [Accepted: 05/25/2019] [Indexed: 12/24/2022]
Affiliation(s)
- Lyudmila Kever
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
| | - Alena Cherezova
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
- Department of PhysiologyMedical College of Georgia, Augusta University1120 15th Street 30912 Augusta GA USA
| | - Valery Zenin
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
| | - Yuri Negulyaev
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
| | - Yan Komissarchik
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
| | - Svetlana Semenova
- Laboratory of Ionic Mechanisms of Cell SignalingInstitute of Cytology of the Russian Academy of ScienceTikhoretsky ave. 4 194064 Saint‐Petersburg Russia
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15
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Enkavi G, Javanainen M, Kulig W, Róg T, Vattulainen I. Multiscale Simulations of Biological Membranes: The Challenge To Understand Biological Phenomena in a Living Substance. Chem Rev 2019; 119:5607-5774. [PMID: 30859819 PMCID: PMC6727218 DOI: 10.1021/acs.chemrev.8b00538] [Citation(s) in RCA: 175] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2018] [Indexed: 12/23/2022]
Abstract
Biological membranes are tricky to investigate. They are complex in terms of molecular composition and structure, functional over a wide range of time scales, and characterized by nonequilibrium conditions. Because of all of these features, simulations are a great technique to study biomembrane behavior. A significant part of the functional processes in biological membranes takes place at the molecular level; thus computer simulations are the method of choice to explore how their properties emerge from specific molecular features and how the interplay among the numerous molecules gives rise to function over spatial and time scales larger than the molecular ones. In this review, we focus on this broad theme. We discuss the current state-of-the-art of biomembrane simulations that, until now, have largely focused on a rather narrow picture of the complexity of the membranes. Given this, we also discuss the challenges that we should unravel in the foreseeable future. Numerous features such as the actin-cytoskeleton network, the glycocalyx network, and nonequilibrium transport under ATP-driven conditions have so far received very little attention; however, the potential of simulations to solve them would be exceptionally high. A major milestone for this research would be that one day we could say that computer simulations genuinely research biological membranes, not just lipid bilayers.
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Affiliation(s)
- Giray Enkavi
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Matti Javanainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Institute
of Organic Chemistry and Biochemistry of the Czech Academy
of Sciences, Flemingovo naḿesti 542/2, 16610 Prague, Czech Republic
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Waldemar Kulig
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
| | - Tomasz Róg
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
| | - Ilpo Vattulainen
- Department
of Physics, University of
Helsinki, P.O. Box 64, FI-00014 Helsinki, Finland
- Computational
Physics Laboratory, Tampere University, P.O. Box 692, FI-33014 Tampere, Finland
- MEMPHYS-Center
for Biomembrane Physics
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16
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Khatun S, Singh A, Pawar N, Gupta AN. Aggregation of amylin: Spectroscopic investigation. Int J Biol Macromol 2019; 133:1242-1248. [PMID: 31028814 DOI: 10.1016/j.ijbiomac.2019.04.167] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/12/2019] [Accepted: 04/23/2019] [Indexed: 12/17/2022]
Abstract
Apart from its relevance to pathology, protein misfolding disease like Type-II Diabetes Mellitus, caused by amyloids of amylin protein has attracted more attention due to structural changes occurring during the aggregation process. We report extensive spectroscopy data of amylin during fibril formation through Raman, FTIR, CD, UV-vis absorption and photoluminescence (PL) spectroscopy. UV-vis and PL spectrum showed the sigmoidal growth of fibril with a lag time of ~2 days, which is consistent with earlier reported work using dynamic light scattering (DLS). Raman spectra revealed the formation of parallel and anti-parallel β-sheet from 0% to 20% with ageing (1st day to 21st day) at pH 6.5 ± 0.1. The results are corroborated by CD and FTIR data. These show the change in β-sheet by 23% at pH 6.5 ± 0.1, 26% at pH = 1.0 ± 0.1 and 30% at pH = 12 ± 0.1. It is also shown that the formation and conversion of other secondary structures into β-sheet is very sensitive towards the pH and ageing. The study may be used for the development of therapeutic strategies that could inhibit or even reverse the process of aggregation.
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Affiliation(s)
- Suparna Khatun
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Anurag Singh
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Nisha Pawar
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India
| | - Amar Nath Gupta
- Biophysics and Soft Matter Laboratory, Department of Physics, Indian Institute of Technology Kharagpur, 721302, India.
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17
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Repulsive interaction induces fibril formation and their growth. Int J Biol Macromol 2019; 123:20-25. [DOI: 10.1016/j.ijbiomac.2018.10.205] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Revised: 10/27/2018] [Accepted: 10/29/2018] [Indexed: 01/27/2023]
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18
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Zhang B, Paffett ML, Naik JS, Jernigan NL, Walker BR, Resta TC. Cholesterol Regulation of Pulmonary Endothelial Calcium Homeostasis. CURRENT TOPICS IN MEMBRANES 2018; 82:53-91. [PMID: 30360783 DOI: 10.1016/bs.ctm.2018.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Cholesterol is a key structural component and regulator of lipid raft signaling platforms critical for cell function. Such regulation may involve changes in the biophysical properties of lipid microdomains or direct protein-sterol interactions that alter the function of ion channels, receptors, enzymes, and membrane structural proteins. Recent studies have implicated abnormal membrane cholesterol levels in mediating endothelial dysfunction that is characteristic of pulmonary hypertensive disorders, including that resulting from long-term exposure to hypoxia. Endothelial dysfunction in this setting is characterized by impaired pulmonary endothelial calcium entry and an associated imbalance that favors production vasoconstrictor and mitogenic factors that contribute to pulmonary hypertension. Here we review current knowledge of cholesterol regulation of pulmonary endothelial Ca2+ homeostasis, focusing on the role of membrane cholesterol in mediating agonist-induced Ca2+ entry and its components in the normal and hypertensive pulmonary circulation.
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Affiliation(s)
- Bojun Zhang
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Michael L Paffett
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Jay S Naik
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Nikki L Jernigan
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Benjimen R Walker
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Thomas C Resta
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States.
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19
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Rawat A, Langen R, Varkey J. Membranes as modulators of amyloid protein misfolding and target of toxicity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1863-1875. [PMID: 29702073 DOI: 10.1016/j.bbamem.2018.04.011] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/19/2018] [Accepted: 04/19/2018] [Indexed: 12/15/2022]
Abstract
Abnormal protein aggregation is a hallmark of various human diseases. α-Synuclein, a protein implicated in Parkinson's disease, is found in aggregated form within Lewy bodies that are characteristically observed in the brains of PD patients. Similarly, deposits of aggregated human islet amyloid polypeptide (IAPP) are found in the pancreatic islets in individuals with type 2 diabetes mellitus. Significant number of studies have focused on how monomeric, disaggregated proteins transition into various amyloid structures leading to identification of a vast number of aggregation promoting molecules and processes over the years. Inasmuch as these factors likely enhance the formation of toxic, misfolded species, they might act as risk factors in disease. Cellular membranes, and particularly certain lipids, are considered to be among the major players for aggregation of α-synuclein and IAPP, and membranes might also be the target of toxicity. Past studies have utilized an array of biophysical tools, both in vitro and in vivo, to expound the membrane-mediated aggregation. Here, we focus on membrane interaction of α-synuclein and IAPP, and how various kinds of membranes catalyze or modulate the aggregation of these proteins and how, in turn, these proteins disrupt membrane integrity, both in vitro and in vivo. The membrane interaction and subsequent aggregation has been briefly contrasted to aggregation of α-synuclein and IAPP in solution. This article is part of a Special Issue entitled: Protein Aggregation and Misfolding at the Cell Membrane Interface edited by Ayyalusamy Ramamoorthy.
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Affiliation(s)
- Anoop Rawat
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States
| | - Ralf Langen
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States.
| | - Jobin Varkey
- Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, CA 90033, United States.
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20
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Singh S, Bhowmick DC, Pany S, Joe M, Zaghlula N, Jeremic AM. Apoptosis signal regulating kinase-1 and NADPH oxidase mediate human amylin evoked redox stress and apoptosis in pancreatic beta-cells. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1721-1733. [PMID: 29627323 DOI: 10.1016/j.bbamem.2018.03.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/22/2018] [Accepted: 03/24/2018] [Indexed: 01/20/2023]
Abstract
Misfolded toxic human islet amyloid polypeptide or amylin (hA) and plasma membrane-associated redox complex, NADPH oxidase (NOX), have been implicated in the islet β-cell demise associated with type-2 diabetes mellitus (T2DM). Studies show that hA accumulation is stressful to β-cells and that misfolding of human amylin evokes redox stress and activates mitogen activated protein (MAP) kinases, p38 MAPK and c-Jun N-terminal (JNK) kinase. However, the molecular link and causality between hA-evoked redox stress, NOX activity and MAP kinases signaling in pancreatic β-cells is incompletely understood. Here, we show that in the process of activating JNK, aggregation prone hA also activates an upstream apoptosis signal regulating kinase-1 (ASK1) with concomitant decrease in intracellular levels of reduced glutathione. Inhibition of ASK1 kinase activity, either by specific ASK1 inhibitor, NQDI1 or by thiol antioxidants reduces human amylin-evoked ASK1 and JNK activation and consequently human amylin toxicity in rat insulinoma Rin-m5F cells and human islets. β-cell specific overexpression of human amylin in mouse islets elicited ASK1 phosphorylation and activation in β-cells but not in other rodent's islet or exocrine cells. This ASK1 activation strongly correlated with islet amyloidosis and diabetes progression. Cytotoxic human amylin additionally stimulated pro-oxidative activity and expressions of plasma membrane bound NADPH oxidase (NOX) and its regulatory subunits. siRNA mediated NOX1 knockdown and selective NOX inhibitors, ML171 and apocynin, significantly reduced hA-induced mitochondrial stress in insulinoma beta-cells. However, NOX inhibitors were largely ineffective against hA-evoked redox stress and activation of cytotoxic ASK1/JNK signaling complex. Thus, our studies suggest that NOX1 and ASK1 autonomously mediate human amylin-evoked redox and mitochondrial stress in pancreatic β-cells.
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Affiliation(s)
- Sanghamitra Singh
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | | | - Satyabrata Pany
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Myungkuk Joe
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Noor Zaghlula
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
| | - Aleksandar M Jeremic
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA.
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21
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Effect of Phosphatidylserine and Cholesterol on Membrane-mediated Fibril Formation by the N-terminal Amyloidogenic Fragment of Apolipoprotein A-I. Sci Rep 2018; 8:5497. [PMID: 29615818 PMCID: PMC5882889 DOI: 10.1038/s41598-018-23920-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 03/22/2018] [Indexed: 01/31/2023] Open
Abstract
Here, we examined the effects of phosphatidylserine (PS) and cholesterol on the fibril-forming properties of the N-terminal 1‒83 fragment of an amyloidogenic G26R variant of apoA-I bound to small unilamellar vesicles. A thioflavin T fluorescence assay together with microscopic observations showed that PS significantly retards the nucleation step in fibril formation by apoA-I 1‒83/G26R, whereas cholesterol slightly enhances fibril formation. Circular dichroism analyses demonstrated that PS facilitates a structural transition from random coil to α-helix in apoA-I 1‒83/G26R with great stabilization of the α-helical structure upon lipid binding. Isothermal titration calorimetry measurements revealed that PS induces a marked increase in capacity for binding of apoA-I 1‒83/G26R to the membrane surface, perhaps due to electrostatic interactions of positively charged amino acids in apoA-I with PS. Such effects of PS to enhance lipid interactions and inhibit fibril formation of apoA-I were also observed for the amyloidogenic region-containing apoA-I 8‒33/G26R peptide. Fluorescence measurements using environment-sensitive probes indicated that PS induces a more solvent-exposed, membrane-bound conformation in the amyloidogenic region of apoA-I without affecting membrane fluidity. Since cell membranes have highly heterogeneous lipid compositions, our findings may provide a molecular basis for the preferential deposition of apoA-I amyloid fibrils in tissues and organs.
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22
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Sasahara K. Membrane-mediated amyloid deposition of human islet amyloid polypeptide. Biophys Rev 2018; 10:453-462. [PMID: 29204886 PMCID: PMC5899711 DOI: 10.1007/s12551-017-0351-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Accepted: 11/14/2017] [Indexed: 01/01/2023] Open
Abstract
Amyloid deposition of human islet amyloid polypeptide (hIAPP) within the islet of Langerhans is closely associated with type II diabetes mellitus. Accumulating evidence indicates that the membrane-mediated aggregation and subsequent deposition of hIAPP are linked to the dysfunction and death of insulin-producing pancreatic β-cells, but the molecular process of hIAPP deposition is poorly understood. In this review, I focus on recent in vitro studies utilizing model membranes to observe the membrane-mediated aggregation/deposition of hIAPP. Membrane surfaces can serve as templates for both hIAPP adsorption and aggregation. Using high-sensitivity surface analyzing/imaging techniques that can characterize the processes of hIAPP aggregation and deposition at the membrane surface, these studies provide valuable insights into the mechanism of membrane damage caused by amyloid deposition of the peptide.
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Affiliation(s)
- Kenji Sasahara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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23
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Zhang X, London E, Raleigh DP. Sterol Structure Strongly Modulates Membrane-Islet Amyloid Polypeptide Interactions. Biochemistry 2018; 57:1868-1879. [PMID: 29373018 DOI: 10.1021/acs.biochem.7b01190] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Amyloid formation has been implicated in a wide range of human diseases, and the interaction of amyloidogenic proteins with membranes are believed to be important for many of them. In type-2 diabetes, human islet amyloid polypeptide (IAPP) forms amyloids, which contribute to β-cell death and dysfunction in the disease. IAPP-membrane interactions are potential mechanisms of cytotoxicity. In vitro studies have shown that cholesterol significantly modulates the ability of model membranes to induce IAPP amyloid formation and IAPP-mediated membrane damage. It is not known if this is due to the general effects of cholesterol on membranes or because of specific sterol-IAPP interactions. The effects of replacing cholesterol with eight other sterols/steroids on IAPP binding to model membranes, membrane disruption, and membrane-mediated amyloid formation were examined. The primary effect of the sterols/steroids on the IAPP-membrane interactions was found to reflect their effect upon membrane order as judged by fluorescence anisotropy measurements. Specific IAPP-sterol/steroid interactions have smaller effects. The fraction of vesicles that bind IAPP was inversely correlated with the sterols/steroids' effect on membrane order, as was the extent of IAPP-induced membrane leakage and the time to form amyloids. The correlation between the fraction of vesicles binding IAPP and membrane leakage was particularly tight, suggesting the restriction of IAPP to a subset of vesicles is responsible for incomplete leakage.
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24
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Extracellular vesicles from human pancreatic islets suppress human islet amyloid polypeptide amyloid formation. Proc Natl Acad Sci U S A 2017; 114:11127-11132. [PMID: 28973954 DOI: 10.1073/pnas.1711389114] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Extracellular vesicles (EVs) are small vesicles released by cells to aid cell-cell communication and tissue homeostasis. Human islet amyloid polypeptide (IAPP) is the major component of amyloid deposits found in pancreatic islets of patients with type 2 diabetes (T2D). IAPP is secreted in conjunction with insulin from pancreatic β cells to regulate glucose metabolism. Here, using a combination of analytical and biophysical methods in vitro, we tested whether EVs isolated from pancreatic islets of healthy patients and patients with T2D modulate IAPP amyloid formation. We discovered that pancreatic EVs from healthy patients reduce IAPP amyloid formation by peptide scavenging, but T2D pancreatic and human serum EVs have no effect. In accordance with these differential effects, the insulin:C-peptide ratio and lipid composition differ between EVs from healthy pancreas and EVs from T2D pancreas and serum. It appears that healthy pancreatic EVs limit IAPP amyloid formation via direct binding as a tissue-specific control mechanism.
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25
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Christensen M, Skeby KK, Schiøtt B. Identification of Key Interactions in the Initial Self-Assembly of Amylin in a Membrane Environment. Biochemistry 2017; 56:4884-4894. [PMID: 28786287 DOI: 10.1021/acs.biochem.7b00344] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Islet amyloid polypeptide, also known as amylin, forms aggregates that reduce the amount of insulin-producing cells in patients with type II diabetes mellitus. Much remains unknown about the process of aggregation and cytotoxicity, but it is known that certain cell membrane components can alter the rate of aggregation. Using atomistic molecular dynamics simulations combined with the highly mobile membrane mimetic model incorporating enhanced sampling of lipid diffusion, we investigate interaction of amylin peptides with the membrane components as well as the self-assembly of amylin. Consistent with experimental evidence, we find that an initial membrane-bound α-helical state folds into stable β-sheet structures upon self-assembly. Our results suggest the following mechanism for the initial phase of amylin self-assembly. The peptides move around on the membrane with the positively charged N-terminus interacting with the negatively charged lipid headgroups. When the peptides start to interact, they partly unfold and break some of the contacts with the membrane. The initial interactions between the peptides are dominated by aromatic and hydrophobic interactions. Oligomers are formed showing both intra- and interpeptide β-sheets, initially with interactions mainly in the C-terminal domain of the peptides. Decreasing the pH to 5.5 is known to inhibit amyloid formation. At low pH, His18 is protonated, adding a fourth positive charge at the peptide. With His18 protonated, no oligomerization is observed in the simulations. The additional charge gives a strong midpoint anchoring of the peptides to negatively charged membrane components, and the peptides experience additional interpeptide repulsion, thereby preventing interactions.
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Affiliation(s)
- Mikkel Christensen
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark.,Sino-Danish Center for Education and Research , Beijing, China
| | - Katrine K Skeby
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
| | - Birgit Schiøtt
- Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University , DK-8000 Aarhus, Denmark
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26
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Sciacca MFM, Lolicato F, Di Mauro G, Milardi D, D'Urso L, Satriano C, Ramamoorthy A, La Rosa C. The Role of Cholesterol in Driving IAPP-Membrane Interactions. Biophys J 2017; 111:140-51. [PMID: 27410742 DOI: 10.1016/j.bpj.2016.05.050] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/15/2016] [Accepted: 05/26/2016] [Indexed: 01/01/2023] Open
Abstract
Our knowledge of the molecular events underlying type 2 diabetes mellitus-a protein conformational disease characterized by the aggregation of islet amyloid polypeptide (IAPP) in pancreatic β cells-is limited. However, amyloid-mediated membrane damage is known to play a key role in IAPP cytotoxicity, and therefore the effects of lipid composition on modulating IAPP-membrane interactions have been the focus of intense research. In particular, membrane cholesterol content varies with aging and consequently with adverse environmental factors such as diet and lifestyle, but its role in the development of the disease is controversial. In this study, we employ a combination of experimental techniques and in silico molecular simulations to shed light on the role of cholesterol in IAPP aggregation and the related membrane disruption. We show that if anionic POPC/POPS vesicles are used as model membranes, cholesterol has a negligible effect on the kinetics of IAPP fibril growth on the surface of the bilayer. In addition, cholesterol inhibits membrane damage by amyloid-induced poration on membranes, but enhances leakage through fiber growth on the membrane surface. Conversely, if 1:2 DOPC/DPPC raft-like model membranes are used, cholesterol accelerates fiber growth. Next, it enhances pore formation and suppresses fiber growth on the membrane surface, leading to leakage. Our results highlight a twofold effect of cholesterol on the amyloidogenicity of IAPP and help explain its debated role in type 2 diabetes mellitus.
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Affiliation(s)
- Michele F M Sciacca
- Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche, Catania, Italy
| | - Fabio Lolicato
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy; Department of Physics, Tampere University of Technology, Tampere, Finland
| | - Giacomo Di Mauro
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy
| | - Danilo Milardi
- Istituto di Biostrutture e Bioimmagini, Consiglio Nazionale delle Ricerche, Catania, Italy
| | - Luisa D'Urso
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy
| | - Cristina Satriano
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy
| | - Ayyalusamy Ramamoorthy
- Biophysics, University of Michigan, Ann Arbor, Michigan; Department of Chemistry, University of Michigan, Ann Arbor, Michigan; Institute for Advanced Study, Technische Universität München, Lichtenbergstrasse, Garching, Germany.
| | - Carmelo La Rosa
- Dipartimento di Scienze Chimiche, Università degli Studi di Catania, Catania, Italy.
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27
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Bhowmick DC, Singh S, Trikha S, Jeremic AM. The Molecular Physiopathogenesis of Islet Amyloidosis. Handb Exp Pharmacol 2017; 245:271-312. [PMID: 29043504 DOI: 10.1007/164_2017_62] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Human islet amyloid polypeptide or amylin (hA) is a 37-amino acid peptide hormone produced and co-secreted with insulin by pancreatic β-cells. Under physiological conditions, hA regulates a broad range of biological processes including insulin release and slowing of gastric emptying, thereby maintaining glucose homeostasis. However, under the pathological conditions associated with type 2 diabetes mellitus (T2DM), hA undergoes a conformational transition from soluble random coil monomers to alpha-helical oligomers and insoluble β-sheet amyloid fibrils or amyloid plaques. There is a positive correlation between hA oligomerization/aggregation, hA toxicity, and diabetes progression. Because the homeostatic balance between hA synthesis, release, and uptake is lost in diabetics and hA aggregation is a hallmark of T2DM, this chapter focuses on the biophysical and cell biology studies investigating molecular mechanisms of hA uptake, trafficking, and degradation in pancreatic cells and its relevance to h's toxicity. We will also discuss the regulatory role of endocytosis and proteolytic pathways in clearance of toxic hA species. Finally, we will discuss potential pharmacological approaches for specific targeting of hA trafficking pathways and toxicity in islet β-cells as potential new avenues toward treatments of T2DM patients.
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Affiliation(s)
| | - Sanghamitra Singh
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA
| | - Saurabh Trikha
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA
| | - Aleksandar M Jeremic
- Department of Biological Sciences, The George Washington University, Washington, DC, 20052, USA.
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28
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Proteasome regulates turnover of toxic human amylin in pancreatic cells. Biochem J 2016; 473:2655-70. [PMID: 27340132 DOI: 10.1042/bcj20160026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Accepted: 06/22/2016] [Indexed: 12/18/2022]
Abstract
Toxic human amylin (hA) oligomers and aggregates are implicated in the pathogenesis of type 2 diabetes mellitus (T2DM). Although recent studies demonstrated a causal connection between hA uptake and toxicity in pancreatic cells, the mechanism of amylin's clearance following its internalization and its relationship to toxicity is yet to be determined, and hence was investigated here. Using pancreatic rat insulinoma β-cells and human islets as model systems, we show that hA, following its internalization, first accumulates in the cytosol followed by its translocation into nucleus, and to a lesser extent lysosomes, keeping the net cytosolic amylin content low. An increase in hA accumulation in the nucleus of pancreatic cells correlated with its cytotoxicity, suggesting that its excessive accumulation in the nucleus is detrimental. hA interacted with 20S core and 19S lid subunits of the β-cell proteasomal complex, as suggested by immunoprecipitation and confocal microscopy studies, which subsequently resulted in a decrease in the proteasome's proteolytic activity in these cells. In vitro binding and activity assays confirmed an intrinsic and potent ability of amylin to interact with the 20S core complex thereby modulating its proteolytic activity. Interestingly, less toxic and aggregation incapable rat amylin (rA) showed a comparable inhibitory effect on proteasome activity and protein ubiquitination, decoupling amylin aggregation/ toxicity and amylin-induced protein stress. In agreement with these studies, inhibition of proteasomal proteolytic activity significantly increased intracellular amylin content and toxicity. Taken together, our results suggest a pivotal role of proteasomes in amylin's turnover and detoxification in pancreatic cells.
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29
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Li H, Ha E, Donaldson RP, Jeremic AM, Vertes A. Rapid assessment of human amylin aggregation and its inhibition by copper(II) ions by laser ablation electrospray ionization mass spectrometry with ion mobility separation. Anal Chem 2016; 87:9829-9837. [PMID: 26352401 DOI: 10.1021/acs.analchem.5b02217] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Native electrospray ionization (ESI) mass spectrometry (MS) is often used to monitor noncovalent complex formation between peptides and ligands. The relatively low throughput of this technique, however, is not compatible with extensive screening. Laser ablation electrospray ionization (LAESI) MS combined with ion mobility separation (IMS) can analyze complex formation and provide conformation information within a matter of seconds. Islet amyloid polypeptide (IAPP) or amylin, a 37-amino acid residue peptide, is produced in pancreatic beta-cells through proteolytic cleavage of its prohormone. Both amylin and its precursor can aggregate and produce toxic oligomers and fibrils leading to cell death in the pancreas that can eventually contribute to the development of type 2 diabetes mellitus. The inhibitory effect of the copper(II) ion on amylin aggregation has been recently discovered, but details of the interaction remain unknown. Finding other more physiologically tolerated approaches requires large scale screening of potential inhibitors. Here, we demonstrate that LAESI-IMS-MS can reveal the binding stoichiometry, copper oxidation state, and the dissociation constant of human amylin-copper(II) complex. The conformations of hIAPP in the presence of copper(II) ions were also analyzed by IMS, and preferential association between the β-hairpin amylin monomer and the metal ion was found. The copper(II) ion exhibited strong association with the -HSSNN- residues of the amylin. In the absence of copper(II), amylin dimers were detected with collision cross sections consistent with monomers of β-hairpin conformation. When copper(II) was present in the solution, no dimers were detected. Thus, the copper(II) ions disrupt the association pathway to the formation of β-sheet rich amylin fibrils. Using LAESI-IMS-MS for the assessment of amylin-copper(II) interactions demonstrates the utility of this technique for the high-throughput screening of potential inhibitors of amylin oligomerization and fibril formation. More generally, this rapid technique opens the door for high-throughput screening of potential inhibitors of amyloid protein aggregation.
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Affiliation(s)
- Hang Li
- Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C. 20052, United States
| | - Emmeline Ha
- Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C. 20052, United States
| | - Robert P Donaldson
- Department of Biological Sciences, The George Washington University, Washington, D.C. 20052, United States
| | - Aleksandar M Jeremic
- Department of Biological Sciences, The George Washington University, Washington, D.C. 20052, United States
| | - Akos Vertes
- Department of Chemistry, W. M. Keck Institute for Proteomics Technology and Applications, The George Washington University, Washington, D.C. 20052, United States
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30
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Abstract
The mechanisms or causes of pancreatic β-cell death as well as impaired insulin secretion, which are the principal events of diabetic etiopathology, are largely unknown. Diabetic complications are known to be associated with abnormal plasma lipid profile, mainly elevated level of cholesterol and free fatty acids. However, in recent years, elevated plasma cholesterol has been implicated as a primary modulator of pancreatic β-cell functions as well as death. High-cholesterol diet in animal models or excess cholesterol in pancreatic β-cell causes transporter desensitization and results in morphometric changes in insulin granules. Moreover, cholesterol is also held responsible to cause oxidative stress, mitochondrial dysfunction, and activation of proapoptotic markers leading to β-cell death. The present review focuses on the pathways and molecularevents that occur in the β-cell under the influence of excess cholesterol that hampers the basal physiology of the cell leading to the progression of diabetes.
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31
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Li Y, Guan L, Lu T, Li H, Li Z, Li F. Interactions of the N-terminal domain of human islet amyloid polypeptide with lipid membranes: the effect of cholesterol. RSC Adv 2016. [DOI: 10.1039/c6ra19714k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cholesterol facilitates the insertion and aggregation of hIAPP1–19 in membrane and the CARC motif mediates the peptide–cholesterol interaction.
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Affiliation(s)
- Yang Li
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Liping Guan
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Tong Lu
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
| | - Haichao Li
- Key Laboratory for Molecular Enzymology & Engineering
- The Ministry of Education
- Jilin University
- Changchun 130012
- P. R. China
| | - Zhengqiang Li
- Key Laboratory for Molecular Enzymology & Engineering
- The Ministry of Education
- Jilin University
- Changchun 130012
- P. R. China
| | - Fei Li
- State Key Laboratory of Supramolecular Structure and Materials
- Jilin University
- Changchun 130012
- P. R. China
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32
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Grouleff J, Irudayam SJ, Skeby KK, Schiøtt B. The influence of cholesterol on membrane protein structure, function, and dynamics studied by molecular dynamics simulations. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:1783-95. [PMID: 25839353 DOI: 10.1016/j.bbamem.2015.03.029] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 03/24/2015] [Accepted: 03/25/2015] [Indexed: 12/12/2022]
Abstract
The plasma membrane, which encapsulates human cells, is composed of a complex mixture of lipids and embedded proteins. Emerging knowledge points towards the lipids as having a regulating role in protein function. Furthermore, insight from protein crystallography has revealed several different types of lipids intimately bound to membrane proteins and peptides, hereby possibly pointing to a site of action for the observed regulation. Cholesterol is among the lipid membrane constituents most often observed to be co-crystallized with membrane proteins, and the cholesterol levels in cell membranes have been found to play an essential role in health and disease. Remarkably little is known about the mechanism of lipid regulation of membrane protein function in health as well as in disease. Herein, we review molecular dynamics simulation studies aimed at investigating the effect of cholesterol on membrane protein and peptide properties. This article is part of a Special Issue entitled: Lipid-protein interactions.
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Affiliation(s)
- Julie Grouleff
- Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Sheeba Jem Irudayam
- Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Katrine K Skeby
- Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark
| | - Birgit Schiøtt
- Department of Chemistry and Interdisciplinary Nanoscience Center, Aarhus University, Langelandsgade 140, 8000 Aarhus C, Denmark.
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33
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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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34
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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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35
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Tomasello MF, Sinopoli A, Pappalardo G. On the Environmental Factors Affecting the Structural and Cytotoxic Properties of IAPP Peptides. J Diabetes Res 2015; 2015:918573. [PMID: 26582441 PMCID: PMC4637107 DOI: 10.1155/2015/918573] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Accepted: 02/05/2015] [Indexed: 12/18/2022] Open
Abstract
Pancreatic islets in type 2 diabetes mellitus (T2DM) patients are characterized by reduced β-cells mass and diffuse extracellular amyloidosis. Amyloid deposition involves the islet amyloid polypeptide (IAPP), a neuropancreatic hormone cosecreted with insulin by β-cells. IAPP is physiologically involved in glucose homeostasis, but it may turn toxic to β-cells owing to its tendency to misfold giving rise to oligomers and fibrils. The process by which the unfolded IAPP starts to self-assemble and the overall factors promoting this conversion are poorly understood. Other open questions are related to the nature of the IAPP toxic species and how exactly β-cells die. Over the last decades, there has been growing consensus about the notion that early molecular assemblies, notably small hIAPP oligomers, are the culprit of β-cells decline. Numerous environmental factors might affect the conformational, aggregation, and cytotoxic properties of IAPP. Herein we review recent progress in the field, focusing on the influences that membranes, pH, and metal ions may have on the conformational conversion and cytotoxicity of full-length IAPP as well as peptide fragments thereof. Current theories proposed for the mechanisms of toxicity will be also summarized together with an outline of the underlying molecular links between IAPP and amyloid beta (Aβ) misfolding.
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Affiliation(s)
| | - Alessandro Sinopoli
- International PhD Program in Translational Biomedicine, University of Catania, Viale A. Doria 6, 95125 Catania, Italy
| | - Giuseppe Pappalardo
- CNR Institute of Biostructures and Bioimaging, Via P. Gaifami 18, 95126 Catania, Italy
- *Giuseppe Pappalardo:
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36
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Caillon L, Duma L, Lequin O, Khemtemourian L. Cholesterol modulates the interaction of the islet amyloid polypeptide with membranes. Mol Membr Biol 2014; 31:239-49. [PMID: 25495656 DOI: 10.3109/09687688.2014.987182] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The deposition of insoluble amyloid fibrils resulting from the aggregation of the human islet amyloid polypeptide (hIAPP) within the islet of Langerhans is a pathological feature of type 2 diabetes mellitus (T2DM). Increasing evidence indicates that biological membranes play a key role in amyloid aggregation, modulating among others the kinetics of amyloid formation, and being the target of toxic species generated during amyloid formation. In T2DM patients, elevated levels of cholesterol, an important determinant of the physical state of biological membranes, are observed in β-cells and are thought to directly impair β-cell function and insulin secretion. However, it is not known whether cholesterol enhances membrane-interaction or membrane-insertion of hIAPP. In this study, we investigated the effect of cholesterol incorporated in zwitterionic and anionic membranes. Our circular dichroism and liquid state NMR data reveal that 10-30% of cholesterol slightly affects the aggregational and conformational behaviour of hIAPP. Additional fluorescence results indicate that 10 and 20% of cholesterol slightly slow down the kinetics of oligomer and fibril formation while anionic lipids accelerate this kinetics. This behavior might be caused by differences in membrane insertion and therefore in membrane binding of hIAPP. The membrane binding affinity was evaluated using (1)H NMR experiments and our results show that the affinity of hIAPP for membranes containing cholesterol is significantly smaller than that for membranes containing anionic lipids. Furthermore, we found that hIAPP-induced membrane damage is synchronized to fibril formation in the absence and in the presence of cholesterol.
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Affiliation(s)
- Lucie Caillon
- Sorbonne Universités , UPMC Univ Paris 06, Laboratoire des Biomolécules , Paris, France
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37
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Sasahara K, Morigaki K, Shinya K. Amyloid aggregation and deposition of human islet amyloid polypeptide at membrane interfaces. FEBS J 2014; 281:2597-612. [PMID: 24702784 DOI: 10.1111/febs.12807] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2013] [Revised: 03/15/2014] [Accepted: 04/04/2014] [Indexed: 11/29/2022]
Abstract
Amyloid deposition of human islet amyloid polypeptide (hIAPP) within the islets of Langerhans is a pathological feature of type 2 diabetes mellitus. Substantial evidence indicates that the membrane-mediated aggregation and subsequent deposition of hIAPP are linked to dysfunction and death of pancreatic β-cells, but the molecular processes of hIAPP deposition are poorly understood. In this study, we examined the membrane-mediated aggregation and deposition of hIAPP at supported planar lipid bilayers with and without raft components (i.e. cholesterol and sphingomyelin) to provide insight into hIAPP-induced membrane dysfunction. The adsorption of hIAPP onto the bilayers was studied using a quartz crystal microbalance with dissipation monitoring, which showed enhanced accumulation of the peptide onto the bilayer containing raft components. Microscope observations demonstrated the growth of the aggregates formed from the membrane-adsorbed hIAPP. The examination of the membrane interfaces revealed that hIAPP aggregates retained the ability to associate with the membranes during the aggregation process, resulting in insertion of the aggregates into the bilayers. We also report the inhibitory effect of insulin on the hIAPP deposition. These findings demonstrate the aggregation of hIAPP at the membrane interfaces leading to amyloid deposits associated with the membrane and suggest a role for insulin in hIAPP deposition. A presumed mechanism regulating hIAPP deposition at the membrane interfaces is discussed.
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Affiliation(s)
- Kenji Sasahara
- Department of Microbiology and Infectious Diseases, Graduate School of Medicine, Kobe University, Japan
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38
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Lee EC, Ha E, Singh S, Legesse L, Ahmad S, Karnaukhova E, Donaldson RP, Jeremic AM. Copper(II)-human amylin complex protects pancreatic cells from amylin toxicity. Phys Chem Chem Phys 2014; 15:12558-71. [PMID: 23793354 DOI: 10.1039/c3cp44542a] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Human amylin-derived oligomers and aggregates are believed to play an important role in the pathogenesis of type II diabetes mellitus (T2DM). In addition to amylin-evoked cell attrition, T2DM is often accompanied by elevated serum copper levels. Although previous studies have shown that human amylin, in the course of its aggregation, produces hydrogen peroxide (H2O2) in solution, and that this process is exacerbated in the presence of copper(ii) ions (Cu(2+)), very little is known about the mechanism of interaction between Cu(2+) and amylin in pancreatic β-cells, including its pathological significance. Hence, in this study we investigated the mechanism by which Cu(2+) and human amylin catalyze formation of reactive oxygen species (ROS) in cells and in vitro, and examined the modulatory effect of Cu(2+) on amylin aggregation and toxicity in pancreatic rat insulinoma (RIN-m5F) β-cells. Our results indicate that Cu(2+) interacts with human and rat amylin to form metalo-peptide complexes with low aggregative and oxidative properties. Human and non-amyloidogenic rat amylin produced minute (nM) amounts of H2O2, the accumulation of which was slightly enhanced in the presence of Cu(2+). In a marked contrast to human and rat amylin, and in the presence of the reducing agents glutathione and ascorbate, Cu(2+) produced μM concentrations of H2O2 surpassing the amylin effect by several fold. The current study shows that human and rat amylin not only produce but also quench H2O2, and that human but not rat amylin significantly decreases the amount of H2O2 in solution produced by Cu(2+) and glutathione. Similarly, human amylin was found to also decrease hydroxyl radical formation elicited by Cu(2+) and glutathione. Furthermore, Cu(2+) mitigated the toxic effect of human amylin by inhibiting activation of pro-apoptotic caspase-3 and stress-kinase signaling pathways in rat pancreatic insulinoma cells in part by stabilizing human amylin in its native conformational state. This sacrificial quenching of metal-catalyzed ROS by human amylin and copper's anti-aggregative and anti-apoptotic properties suggest a novel and protective role for the copper-amylin complex.
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Affiliation(s)
- Elizabeth C Lee
- Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA
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39
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Trikha S, Jeremic AM. Distinct internalization pathways of human amylin monomers and its cytotoxic oligomers in pancreatic cells. PLoS One 2013; 8:e73080. [PMID: 24019897 PMCID: PMC3760900 DOI: 10.1371/journal.pone.0073080] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/15/2013] [Indexed: 01/06/2023] Open
Abstract
Toxic human amylin oligomers and aggregates are implicated in the pathogenesis of type 2 diabetes mellitus (TTDM). Although recent studies have shown that pancreatic cells can recycle amylin monomers and toxic oligomers, the exact uptake mechanism and trafficking routes of these molecular forms and their significance for amylin toxicity are yet to be determined. Using pancreatic rat insulinoma (RIN-m5F) beta (β)-cells and human islets as model systems we show that monomers and oligomers cross the plasma membrane (PM) through both endocytotic and non-endocytotic (translocation) mechanisms, the predominance of which is dependent on amylin concentrations and incubation times. At low (≤ 100 nM) concentrations, internalization of amylin monomers in pancreatic cells is completely blocked by the selective amylin-receptor (AM-R) antagonist, AC-187, indicating an AM-R dependent mechanism. In contrast at cytotoxic (µM) concentrations monomers initially (1 hour) enter pancreatic cells by two distinct mechanisms: translocation and macropinocytosis. However, during the late stage (24 hours) monomers internalize by a clathrin-dependent but AM-R and macropinocytotic independent pathway. Like monomers a small fraction of the oligomers initially enter cells by a non-endocytotic mechanism. In contrast a majority of the oligomers at both early (1 hour) and late times (24 hours) traffic with a fluid-phase marker, dextran, to the same endocytotic compartments, the uptake of which is blocked by potent macropinocytotic inhibitors. This led to a significant increase in extra-cellular PM accumulation, in turn potentiating amylin toxicity in pancreatic cells. Our studies suggest that macropinocytosis is a major but not the only clearance mechanism for both amylin's molecular forms, thereby serving a cyto-protective role in these cells.
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Affiliation(s)
- Saurabh Trikha
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia, United States of America
| | - Aleksandar M. Jeremic
- Department of Biological Sciences, The George Washington University, Washington, District of Columbia, United States of America
- * E-mail:
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40
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Caillon L, Lequin O, Khemtémourian L. Evaluation of membrane models and their composition for islet amyloid polypeptide-membrane aggregation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2091-8. [PMID: 23707907 DOI: 10.1016/j.bbamem.2013.05.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 04/26/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023]
Abstract
Human islet amyloid polypeptide (IAPP) forms amyloid fibrils in the pancreatic islets of patients suffering from type 2 diabetes mellitus (T2DM). The formation of IAPP fibrils has been shown to cause membrane damage which most likely is responsible for the death of pancreatic islet β-cells during the pathogenesis of T2DM. Several studies have demonstrated a clear interaction between IAPP and lipid membranes. However the effect of different lipid compositions and of various membrane mimetics (including micelles, bicelles, SUV and LUV) on fibril formation kinetics and fibril morphology has not yet systematically been analysed. Here we report that the interaction of IAPP with various membrane models promoted different processes of fibril formation. Our data reveal that in SDS and DPC micelles, IAPP adopts a stable α-helical structure for several days, suggesting that the micelle models may stabilize monomeric or small oligomeric species of IAPP. In contrast, zwitterionic DMPC/DHPC bicelles and DOPC SUV accelerate the fibril formation compared to zwitterionic DOPC LUV, indicating that the size of the membrane model and its curvature influence the fibrillation process. Negatively charged membranes decrease the lag-time of the fibril formation kinetics while phosphatidylethanolamine and cholesterol have an opposite effect, probably due to the modulation of the physical properties of the membrane and/or due to direct interactions with IAPP within the membrane core. Finally, our results show that the modulation of lipid composition influences not only the growth of fibrils at the membrane surface but also the interactions of β-sheet oligomers with membranes.
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Key Words
- 1,1,1,3,3,3-hexafluoro-2-propanol
- 1,2-dihexanoyl-sn-glycero-3-phosphocholine
- 1,2-dimyristoyl-sn-glycero-3-phosphocholine
- 1,2-dioleoyl-sn-glycero-3-phospho-(1′-rac-glycerol)
- 1,2-dioleoyl-sn-glycero-3-phospho-L-serine
- 1,2-dioleoyl-sn-glycero-3-phosphocholine
- 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine
- 1,2-dipalmitoyl-sn-glycero-3-phosphocholine
- 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine
- Aggregation kinetics
- Amyloid
- CD
- Chol
- DHPC
- DMPC
- DMSO
- DOPC
- DOPE
- DOPG
- DOPS
- DPC
- DPPC
- Fibril morphology
- HFIP
- IAPP
- LUV
- Model membranes (LUV SUV, bicelles, micelles)
- POPC
- Phospholipid
- SDS
- SM
- ThT
- Thioflavin T
- cholesterol
- circular dichroism
- dimethyl sulfoxide
- dodecyl phosphocholine
- human Islet Amyloid Polypeptide
- large unilamellar vesicle
- sodium dodecyl sulphate
- sphingomyelin
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Affiliation(s)
- Lucie Caillon
- UPMC Univ Paris 06, UMR 7203 CNRS-UPMC-ENS, Laboratoire des Biomolécules, 4 place Jussieu, 75005 Paris, France
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41
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Sciacca MFM, Brender JR, Lee DK, Ramamoorthy A. Phosphatidylethanolamine enhances amyloid fiber-dependent membrane fragmentation. Biochemistry 2012; 51:7676-84. [PMID: 22970795 DOI: 10.1021/bi3009888] [Citation(s) in RCA: 99] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The toxicity of amyloid-forming peptides has been hypothesized to reside in the ability of protein oligomers to interact with and disrupt the cell membrane. Much of the evidence for this hypothesis comes from in vitro experiments using model membranes. However, the accuracy of this approach depends on the ability of the model membrane to accurately mimic the cell membrane. The effect of membrane composition has been overlooked in many studies of amyloid toxicity in model systems. By combining measurements of membrane binding, membrane permeabilization, and fiber formation, we show that lipids with the phosphatidylethanolamine (PE) headgroup strongly modulate the membrane disruption induced by IAPP (islet amyloid polypeptide protein), an amyloidogenic protein involved in type II diabetes. Our results suggest that PE lipids hamper the interaction of prefibrillar IAPP with membranes but enhance the membrane disruption correlated with the growth of fibers on the membrane surface via a detergent-like mechanism. These findings provide insights into the mechanism of membrane disruption induced by IAPP, suggesting a possible role of PE and other amyloids involved in other pathologies.
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Affiliation(s)
- Michele F M Sciacca
- Departments of Biophysics and Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States
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42
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Sasahara K, Morigaki K, Okazaki T, Hamada D. Binding of Islet Amyloid Polypeptide to Supported Lipid Bilayers and Amyloid Aggregation at the Membranes. Biochemistry 2012; 51:6908-19. [DOI: 10.1021/bi300542g] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Kenji Sasahara
- Division of Structural Biology
(G-COE), Department of Biochemistry and Molecular Biology, Graduate
School of Medicine, Kobe University, Kobe
650-0017, Japan
| | - Kenichi Morigaki
- National Institute of Advanced Industrial Science and Technology (AIST), Ikeda 563-8577, Japan
- Research Center for Environmental
Genomics, Kobe University, Kobe 657-8501,
Japan
| | - Takashi Okazaki
- National Institute of Advanced Industrial Science and Technology (AIST), Ikeda 563-8577, Japan
| | - Daizo Hamada
- Division of Structural Biology
(G-COE), Department of Biochemistry and Molecular Biology, Graduate
School of Medicine, Kobe University, Kobe
650-0017, Japan
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43
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Bucciantini M, Nosi D, Forzan M, Russo E, Calamai M, Pieri L, Formigli L, Quercioli F, Soria S, Pavone F, Savistchenko J, Melki R, Stefani> M. Toxic effects of amyloid fibrils on cell membranes: the importance of ganglioside GM1. FASEB J 2011; 26:818-31. [DOI: 10.1096/fj.11-189381] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Monica Bucciantini
- Department of Biochemical Sciences, and Forensic MedicineUniversity of Florence Florence Italy
- Research Centre on the Molecular Basis of Neurodegeneration, and Forensic MedicineUniversity of Florence Florence Italy
| | - Daniele Nosi
- Department of Anatomy, Histology, and Forensic MedicineUniversity of Florence Florence Italy
| | - Mario Forzan
- Department of Animal Pathology, Food Prophylaxis, and HygieneUniversity of Pisa Pisa Italy
| | - Edda Russo
- Department of Biochemical Sciences, and Forensic MedicineUniversity of Florence Florence Italy
| | - Martino Calamai
- European Laboratory for Nonlinear Spectroscopy (LENS)University of Florence Florence Italy
| | - Laura Pieri
- Laboratoire d'Enzymologie et Biochimie StructuralesCentre National de la Recherche Scientifique Gif sur Yvette France
| | - Lucia Formigli
- Department of Anatomy, Histology, and Forensic MedicineUniversity of Florence Florence Italy
| | - Franco Quercioli
- National Institute of OpticsConsiglio Nazionale delle Ricerche Florence Research Area Florence Italy
| | - Silvia Soria
- Nello Carrara Institute of Applied PhysicsConsiglio Nazionale delle Ricerche Florence Research Area Florence Italy
| | - Francesco Pavone
- European Laboratory for Nonlinear Spectroscopy (LENS)University of Florence Florence Italy
| | - Jimmy Savistchenko
- Laboratoire d'Enzymologie et Biochimie StructuralesCentre National de la Recherche Scientifique Gif sur Yvette France
| | - Ronald Melki
- Department of Animal Pathology, Food Prophylaxis, and HygieneUniversity of Pisa Pisa Italy
- Laboratoire d'Enzymologie et Biochimie StructuralesCentre National de la Recherche Scientifique Gif sur Yvette France
| | - Massimo Stefani>
- Department of Biochemical Sciences, and Forensic MedicineUniversity of Florence Florence Italy
- Research Centre on the Molecular Basis of Neurodegeneration, and Forensic MedicineUniversity of Florence Florence Italy
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44
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Xu W, Wei G, Su H, Nordenskiöld L, Mu Y. Effects of cholesterol on pore formation in lipid bilayers induced by human islet amyloid polypeptide fragments: a coarse-grained molecular dynamics study. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2011; 84:051922. [PMID: 22181459 DOI: 10.1103/physreve.84.051922] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Indexed: 05/31/2023]
Abstract
Disruption of the cellular membrane by the amyloidogenic peptide, islet amyloid polypeptide (IAPP), has been considered as one of the mechanisms of β-cell death during type 2 diabetes. The N-terminal region (residues 1-19) of the human version of IAPP is suggested to be primarily responsible for the membrane-disrupting effect of the full-length hIAPP peptide. However, the detailed assembly mode of hIAPP1-19 with membrane remains unclear. To gain insight into the interactions of hIAPP1-19 oligomer with the model membrane, we have employed coarse-grained molecular dynamics self-assembly simulations to study the aggregation of hIAPP1-19 fragments in the binary lipid made of zwitterionic dipalmitoylphosphatidylcholine (DPPC) and anionic dipalmitoylphosphatidylserine (DPPS) in the presence and absence of different levels of cholesterol content. The membrane-destabilizing effect of hIAPP1-19 is found to be modulated by the presence of cholesterol. In the absence of cholesterol, hIAPP1-19 aggregates prefer to locate inside the bilayer, forming pore-like assemblies. While in the presence of cholesterol molecules, the lipid bilayer becomes more ordered and stiff, and the hIAPP1-19 aggregates are dominantly positioned at the bilayer-water interface. The action of cholesterol may suggest a possible way to maintain the membrane integrity by small molecule interference.
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Affiliation(s)
- Weixin Xu
- State Key Laboratory of Precision Spectroscopy, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, China
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45
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Trikha S, Jeremic AM. Clustering and internalization of toxic amylin oligomers in pancreatic cells require plasma membrane cholesterol. J Biol Chem 2011; 286:36086-36097. [PMID: 21865171 DOI: 10.1074/jbc.m111.240762] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Self-assembly of the human pancreatic hormone amylin into toxic oligomers and aggregates is linked to dysfunction of islet β-cells and pathogenesis of type 2 diabetes mellitus. Recent evidence suggests that cholesterol, an essential component of eukaryotic cells membranes, controls amylin aggregation on model membranes. However, the pathophysiological consequence of cholesterol-regulated amylin polymerization on membranes and biochemical mechanisms that protect β-cells from amylin toxicity are poorly understood. Here, we report that plasma membrane (PM) cholesterol plays a key role in molecular recognition, sorting, and internalization of toxic amylin oligomers but not monomers in pancreatic rat insulinoma and human islet cells. Depletion of PM cholesterol or the disruption of the cytoskeleton network inhibits internalization of amylin oligomers, which in turn enhances extracellular oligomer accumulation and potentiates amylin toxicity. Confocal microscopy reveals an increased nucleation of amylin oligomers across the plasma membrane in cholesterol-depleted cells, with a 2-fold increase in cell surface coverage and a 3-fold increase in their number on the PM. Biochemical studies confirm accumulation of amylin oligomers in the medium after depletion of PM cholesterol. Replenishment of PM cholesterol from intracellular cholesterol stores or by the addition of water-soluble cholesterol restores amylin oligomer clustering at the PM and internalization, which consequently diminishes cell surface coverage and toxicity of amylin oligomers. In contrast to oligomers, amylin monomers followed clathrin-dependent endocytosis, which is not sensitive to cholesterol depletion. Our studies identify an actin-mediated and cholesterol-dependent mechanism for selective uptake and clearance of amylin oligomers, impairment of which greatly potentiates amylin toxicity.
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Affiliation(s)
- Saurabh Trikha
- Department of Biological Sciences, The George Washington University, Washington, D. C. 20052
| | - Aleksandar M Jeremic
- Department of Biological Sciences, The George Washington University, Washington, D. C. 20052.
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Kawahara M, Ohtsuka I, Yokoyama S, Kato-Negishi M, Sadakane Y. Membrane Incorporation, Channel Formation, and Disruption of Calcium Homeostasis by Alzheimer's β-Amyloid Protein. Int J Alzheimers Dis 2011; 2011:304583. [PMID: 21547225 PMCID: PMC3087492 DOI: 10.4061/2011/304583] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2010] [Revised: 12/22/2010] [Accepted: 01/27/2011] [Indexed: 01/09/2023] Open
Abstract
Oligomerization, conformational changes, and the consequent neurodegeneration of Alzheimer's β-amyloid protein (AβP) play crucial roles in the pathogenesis of Alzheimer's disease (AD). Mounting evidence suggests that oligomeric AβPs cause the disruption of calcium homeostasis, eventually leading to neuronal death. We have demonstrated that oligomeric AβPs directly incorporate into neuronal membranes, form cation-sensitive ion channels (“amyloid channels”), and cause the disruption of calcium homeostasis via the amyloid channels. Other disease-related amyloidogenic proteins, such as prion protein in prion diseases or α-synuclein in dementia with Lewy bodies, exhibit similarities in the incorporation into membranes and the formation of calcium-permeable channels. Here, based on our experimental results and those of numerous other studies, we review the current understanding of the direct binding of AβP into membrane surfaces and the formation of calcium-permeable channels. The implication of composition of membrane lipids and the possible development of new drugs by influencing membrane properties and attenuating amyloid channels for the treatment and prevention of AD is also discussed.
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Affiliation(s)
- Masahiro Kawahara
- Department of Analytical Chemistry, School of Pharmaceutical Sciences, Kyushu University of Health and Welfare, 1714-1 Yoshino-cho, Nobeoka-shi, Miyazaki 882-8508, Japan
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47
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Brender JR, Lee EL, Hartman K, Wong PT, Ramamoorthy A, Steel DG, Gafni A. Biphasic effects of insulin on islet amyloid polypeptide membrane disruption. Biophys J 2011; 100:685-692. [PMID: 21281583 PMCID: PMC3030259 DOI: 10.1016/j.bpj.2010.09.070] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2010] [Revised: 09/09/2010] [Accepted: 09/27/2010] [Indexed: 10/18/2022] Open
Abstract
Type II diabetes, in its late stages, is often associated with the formation of extracellular islet amyloid deposits composed of islet amyloid polypeptide (IAPP or amylin). IAPP is stored before secretion at millimolar concentrations within secretory granules inside the β-cells. Of interest, at these same concentrations in vitro, IAPP rapidly aggregates and forms fibrils, yet within secretory granules of healthy individuals, IAPP does not fibrillize. Insulin is also stored within the secretory granules before secretion, and has been shown in vitro to inhibit IAPP fibril formation. Because of insulin's inhibitory effect on IAPP fibrillization, it has been suggested that insulin may also inhibit IAPP-mediated permeabilization of the β-cell plasma membrane in vivo. We show that although insulin is effective at preventing fiber-dependent membrane disruption, it is not effective at stopping the initial phase of membrane disruption before fibrillogenesis, and does not prevent the formation of small IAPP oligomers on the membrane. These results suggest that insulin has a more complicated role in inhibiting IAPP fibrillogenesis, and that other factors, such as the low pH of the secretory granule, may also play a role.
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Affiliation(s)
- Jeffrey R Brender
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan; Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Edgar L Lee
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Kevin Hartman
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan; Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Pamela T Wong
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Ayyalusamy Ramamoorthy
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan; Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Duncan G Steel
- Department of Biophysics, University of Michigan, Ann Arbor, Michigan; Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan; Department of Physics, University of Michigan, Ann Arbor, Michigan
| | - Ari Gafni
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan; Department of Biophysics, University of Michigan, Ann Arbor, Michigan.
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48
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Butterfield SM, Lashuel HA. Amyloidogenic protein-membrane interactions: mechanistic insight from model systems. Angew Chem Int Ed Engl 2011; 49:5628-54. [PMID: 20623810 DOI: 10.1002/anie.200906670] [Citation(s) in RCA: 483] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The toxicity of amyloid-forming proteins is correlated with their interactions with cell membranes. Binding events between amyloidogenic proteins and membranes result in mutually disruptive structural perturbations, which are associated with toxicity. Membrane surfaces promote the conversion of amyloid-forming proteins into toxic aggregates, and amyloidogenic proteins, in turn, compromise the structural integrity of the cell membrane. Recent studies with artificial model membranes have highlighted the striking resemblance of the mechanisms of membrane permeabilization of amyloid-forming proteins to those of pore-forming toxins and antimicrobial peptides.
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Affiliation(s)
- Sara M Butterfield
- Laboratory of Molecular Neurobiology and Neuroproteomics, Swiss Federal Institute of Technology Lausanne (EPFL), SV-BMI-LMNN AI2351, 1015 Lausanne, Switzerland
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49
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Molecular insights into amyloid regulation by membrane cholesterol and sphingolipids: common mechanisms in neurodegenerative diseases. Expert Rev Mol Med 2010; 12:e27. [PMID: 20807455 PMCID: PMC2931503 DOI: 10.1017/s1462399410001602] [Citation(s) in RCA: 135] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Alzheimer, Parkinson and other neurodegenerative diseases involve a series of brain
proteins, referred to as ‘amyloidogenic proteins’, with exceptional
conformational plasticity and a high propensity for self-aggregation. Although the
mechanisms by which amyloidogenic proteins kill neural cells are not fully understood, a
common feature is the concentration of unstructured amyloidogenic monomers on
bidimensional membrane lattices. Membrane-bound monomers undergo a series of
lipid-dependent conformational changes, leading to the formation of oligomers of varying
toxicity rich in β-sheet structures (annular pores, amyloid fibrils) or in
α-helix structures (transmembrane channels). Condensed membrane nano- or
microdomains formed by sphingolipids and cholesterol are privileged sites for the binding
and oligomerisation of amyloidogenic proteins. By controlling the balance between
unstructured monomers and α or β conformers (the chaperone effect),
sphingolipids can either inhibit or stimulate the oligomerisation of amyloidogenic
proteins. Cholesterol has a dual role: regulation of protein–sphingolipid
interactions through a fine tuning of sphingolipid conformation (indirect effect), and
facilitation of pore (or channel) formation through direct binding to amyloidogenic
proteins. Deciphering this complex network of molecular interactions in the context of
age- and disease-related evolution of brain lipid expression will help understanding of
how amyloidogenic proteins induce neural toxicity and will stimulate the development of
innovative therapies for neurodegenerative diseases.
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50
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Abstract
Gut microbiota is an assortment of microorganisms inhabiting the length and width of the mammalian gastrointestinal tract. The composition of this microbial community is host specific, evolving throughout an individual's lifetime and susceptible to both exogenous and endogenous modifications. Recent renewed interest in the structure and function of this "organ" has illuminated its central position in health and disease. The microbiota is intimately involved in numerous aspects of normal host physiology, from nutritional status to behavior and stress response. Additionally, they can be a central or a contributing cause of many diseases, affecting both near and far organ systems. The overall balance in the composition of the gut microbial community, as well as the presence or absence of key species capable of effecting specific responses, is important in ensuring homeostasis or lack thereof at the intestinal mucosa and beyond. The mechanisms through which microbiota exerts its beneficial or detrimental influences remain largely undefined, but include elaboration of signaling molecules and recognition of bacterial epitopes by both intestinal epithelial and mucosal immune cells. The advances in modeling and analysis of gut microbiota will further our knowledge of their role in health and disease, allowing customization of existing and future therapeutic and prophylactic modalities.
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Affiliation(s)
- Inna Sekirov
- Michael Smith Laboratories, Department of Microbiology and Immunology, The University of British Columbia, Vancouver, British Columbia, Canada
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