1
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Park J, Cheong DY, Lee G, Han CE. Deep learning-based denoising for unbiased analysis of morphology and stiffness in amyloid fibrils. Comput Biol Med 2025; 184:109410. [PMID: 39577350 DOI: 10.1016/j.compbiomed.2024.109410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2024] [Revised: 11/08/2024] [Accepted: 11/08/2024] [Indexed: 11/24/2024]
Abstract
Understanding the morphology of amyloid fibrils is crucial for comprehending the aggregation and degradation mechanisms of abnormal proteins implicated in various diseases, such as Alzheimer's disease, Parkinson's disease, type II diabetes, and various forms of amyloidosis. Atomic force microscopy (AFM) stands as the most representative method for studying amyloid fibril morphology. However, obstacles in AFM images, including noise, salt, and amorphous aggregates, often impede accurate sample quantification. In this study, we developed denoising software employing a U-Net deep learning architecture to address this issue. The software efficiently eliminated various impediments that interfere with fibril analysis in noisy AFM images, thereby facilitating precise quantification of amyloid fibrils. We also developed automated fibril analysis technologies using the denoised AFM images, leading to quicker, more precise, and more objective assessments of fibril morphology. Furthermore, we presented a method for fibril stiffness extraction from a modulus image through mask creation based on a denoised height image. Our approach secures time efficiency and precision in analyzing amyloid morphology, and we believe it will significantly advance the currently stagnant research on amyloid-related diseases.
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Affiliation(s)
- Jaehee Park
- Department of Electronics and Information Engineering, Korea University, Sejong, 30019, Republic of Korea; Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, 30019, Republic of Korea
| | - Da Yeon Cheong
- Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, 30019, Republic of Korea; Department of Biotechnology and Bioinformatics, Korea University, Sejong, 30019, Republic of Korea
| | - Gyudo Lee
- Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, 30019, Republic of Korea; Department of Biotechnology and Bioinformatics, Korea University, Sejong, 30019, Republic of Korea
| | - Cheol E Han
- Department of Electronics and Information Engineering, Korea University, Sejong, 30019, Republic of Korea; Interdisciplinary Graduate Program for Artificial Intelligence Smart Convergence Technology, Korea University, Sejong, 30019, Republic of Korea.
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2
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Ziaunys M, Mikalauskaite K, Sakalauskas A, Smirnovas V. Study of Insulin Aggregation and Fibril Structure under Different Environmental Conditions. Int J Mol Sci 2024; 25:9406. [PMID: 39273350 PMCID: PMC11395423 DOI: 10.3390/ijms25179406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2024] [Revised: 08/27/2024] [Accepted: 08/28/2024] [Indexed: 09/15/2024] Open
Abstract
Protein amyloid aggregation is linked with widespread and fatal neurodegenerative disorders as well as several amyloidoses. Insulin, a small polypeptide hormone, is associated with injection-site amyloidosis and is a popular model protein for in vitro studies of amyloid aggregation processes as well as in the search for potential anti-amyloid compounds. Despite hundreds of studies conducted with this specific protein, the procedures used have employed a vast array of different means of achieving fibril formation. These conditions include the use of different solution components, pH values, ionic strengths, and other additives. In turn, this variety of conditions results in the generation of fibrils with different structures, morphologies and stabilities, which severely limits the possibility of cross-study comparisons as well as result interpretations. In this work, we examine the condition-structure relationship of insulin amyloid aggregation under a range of commonly used pH and ionic strength conditions as well as solution components. We demonstrate the correlation between the reaction solution properties and the resulting aggregation kinetic parameters, aggregate secondary structures, morphologies, stabilities and dye-binding modes.
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Affiliation(s)
| | | | | | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania; (M.Z.); (K.M.); (A.S.)
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3
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Louros N, Schymkowitz J, Rousseau F. Mechanisms and pathology of protein misfolding and aggregation. Nat Rev Mol Cell Biol 2023; 24:912-933. [PMID: 37684425 DOI: 10.1038/s41580-023-00647-2] [Citation(s) in RCA: 36] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/28/2023] [Indexed: 09/10/2023]
Abstract
Despite advances in machine learning-based protein structure prediction, we are still far from fully understanding how proteins fold into their native conformation. The conventional notion that polypeptides fold spontaneously to their biologically active states has gradually been replaced by our understanding that cellular protein folding often requires context-dependent guidance from molecular chaperones in order to avoid misfolding. Misfolded proteins can aggregate into larger structures, such as amyloid fibrils, which perpetuate the misfolding process, creating a self-reinforcing cascade. A surge in amyloid fibril structures has deepened our comprehension of how a single polypeptide sequence can exhibit multiple amyloid conformations, known as polymorphism. The assembly of these polymorphs is not a random process but is influenced by the specific conditions and tissues in which they originate. This observation suggests that, similar to the folding of native proteins, the kinetics of pathological amyloid assembly are modulated by interactions specific to cells and tissues. Here, we review the current understanding of how intrinsic protein conformational propensities are modulated by physiological and pathological interactions in the cell to shape protein misfolding and aggregation pathology.
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Affiliation(s)
- Nikolaos Louros
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Joost Schymkowitz
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium.
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
| | - Frederic Rousseau
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, Leuven, Belgium.
- Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
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4
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Kamelnia R, Goliaei B, Peyman Shariatpanahi S, Mehrnejad F, Ghasemi A, Zare Karizak A, Ebrahim-Habibi A. Chemical Modification of the Amino Groups of Human Insulin: Investigating Structural Properties and Amorphous Aggregation of Acetylated Species. Protein J 2023:10.1007/s10930-023-10131-7. [PMID: 37395911 DOI: 10.1007/s10930-023-10131-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2023] [Indexed: 07/04/2023]
Abstract
The efficacy of human recombinant insulin can be affected by its aggregation. Effects of acetylation were observed on insulin structure, stability, and aggregation at 37 and 50 °C and pH of 5.0 and 7.4 with the use of spectroscopy, circular dichroism (CD), dynamic light scattering (DLS), and atomic force microscopy (AFM). Raman and FTIR results were indicative of structural changes in AC-INS, and CD analyses showed a slight increase in β-sheet content in AC-INS. Melting temperature (Tm) measurements indicated an overall more stable structure and spectroscopic assessment showed a more compact one. Formation of amorphous aggregates was followed over time and kinetics parameters showed a longer nucleation phase (higher t* amount) and lower aggregates amount (lower Alim) for acetylated insulin (AC-INS) compared to native (N-INS) in all tested conditions. The results of amyloid-specific probes approved the formation of amorphous aggregates. Size particle and microscopic analysis suggested that AC-INS was less prone to form aggregates, which were smaller if formed. In conclusion, this study has demonstrated that controlled acetylation of insulin may lead to its higher stability and lower propensity toward amorphous aggregation and has provided insight into the result of this type of post-translational protein modification.
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Affiliation(s)
- Reyhane Kamelnia
- Laboratory of Biophysics and Molecular Biology, Departments of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., P.O. Box 13145-1384, Tehran, Iran
| | - Bahram Goliaei
- Laboratory of Biophysics and Molecular Biology, Departments of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., P.O. Box 13145-1384, Tehran, Iran.
| | - Seyed Peyman Shariatpanahi
- Laboratory of Biophysics and Molecular Biology, Departments of Biophysics, Institute of Biochemistry and Biophysics, University of Tehran, 16th Azar St., Enghelab Sq., P.O. Box 13145-1384, Tehran, Iran
| | - Faramarz Mehrnejad
- Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran, Tehran, Iran
| | - Atiyeh Ghasemi
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Ashkan Zare Karizak
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Azadeh Ebrahim-Habibi
- Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Jalal Al Ahmad Highway, Tehran, 1411713137, Iran.
- Endocrinology and Metabolism Research Center, Endocrinology and Metabolism Clinical Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
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5
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Vanik V, Bednarikova Z, Fabriciova G, Wang SSS, Gazova Z, Fedunova D. Modulation of Insulin Amyloid Fibrillization in Imidazolium-Based Ionic Liquids with Hofmeister Series Anions. Int J Mol Sci 2023; 24:ijms24119699. [PMID: 37298650 DOI: 10.3390/ijms24119699] [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: 05/20/2023] [Revised: 05/30/2023] [Accepted: 05/30/2023] [Indexed: 06/12/2023] Open
Abstract
Amyloid fibrils have immense potential to become the basis of modern biomaterials. The formation of amyloid fibrils in vitro strongly depends on the solvent properties. Ionic liquids (ILs), alternative solvents with tunable properties, have been shown to modulate amyloid fibrillization. In this work, we studied the impact of five ILs with 1-ethyl-3-methylimidazolium cation [EMIM+] and anions of Hofmeisterseries hydrogen sulfate [HSO4-], acetate [AC-], chloride [Cl-], nitrate [NO3-], and tetrafluoroborate [BF4-] on the kinetics of insulin fibrillization and morphology, and the structure of insulin fibrils when applying fluorescence spectroscopy, AFM and ATR-FTIR spectroscopy. We found that the studied ILs were able to speed up the fibrillization process in an anion- and IL-concentration-dependent manner. At an IL concentration of 100 mM, the efficiency of the anions at promoting insulin amyloid fibrillization followed the reverse Hofmeister series, indicating the direct binding of ions with the protein surface. At a concentration of 25 mM, fibrils with different morphologies were formed, yet with similar secondary structure content. Moreover, no correlation with the Hofmeister ranking was detected for kinetics parameters. IL with the kosmotropic strongly hydrated [HSO4-] anion induced the formation of large amyloid fibril clusters, while the other kosmotropic anion [AC-] along with [Cl-] led to the formation of fibrils with similar needle-like morphologies to those formed in the IL-free solvent. The presence of the ILs with the chaotropic anions [NO3-] and [BF4-] resulted in longer laterally associated fibrils. The effect of the selected ILs was driven by a sensitive balance and interplay between specific protein-ion and ion-water interactions and non-specific long-range electrostatic shielding.
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Affiliation(s)
- Vladimir Vanik
- Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Košice, Slovakia
| | - Zuzana Bednarikova
- Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Košice, Slovakia
| | - Gabriela Fabriciova
- Department of Biophysics, Faculty of Science, Pavol Jozef Šafárik University in Košice, 041 54 Košice, Slovakia
| | - Steven S-S Wang
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Zuzana Gazova
- Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Košice, Slovakia
| | - Diana Fedunova
- Institute of Experimental Physics, Slovak Academy of Sciences, 040 01 Košice, Slovakia
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6
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Exploring Epigallocatechin-3-Gallate Autoxidation Products: Specific Incubation Times Required for Emergence of Anti-Amyloid Properties. Antioxidants (Basel) 2022; 11:antiox11101887. [PMID: 36290609 PMCID: PMC9598636 DOI: 10.3390/antiox11101887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 09/16/2022] [Accepted: 09/19/2022] [Indexed: 11/16/2022] Open
Abstract
Amyloidogenic protein/peptide aggregation into fibrillar aggregates is associated with multiple amyloidoses, including widespread neurodegenerative disorders. Despite years of research and a well-understood mechanism, there are still very few treatments available for the increasing number of amyloid-related disorders. In recent years, the search for potential anti-aggregation compounds has shifted toward naturally occurring molecules, with one of the most promising being epigallocatechin-3-gallate (EGCG). This polyphenolic compound was shown to inhibit the aggregation of several amyloidogenic proteins/peptides, including amyloid-beta (related to Alzheimer’s disease) and alpha-synuclein (related to Parkinson’s disease). However, multiple reports have indicated its limited stability under physiological conditions and the possibility of EGCG autoxidation products being the actual inhibitory compounds. In this work, we explore how different EGCG autoxidation products associate with non-aggregated insulin, as well as how they affect its aggregation and resulting fibril structure. We also show that there is a specific incubation time required for the emergence of compounds, which alters the amyloid aggregation process.
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7
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Mikalauskaite K, Ziaunys M, Smirnovas V. Lysozyme Amyloid Fibril Structural Variability Dependence on Initial Protein Folding State. Int J Mol Sci 2022; 23:5421. [PMID: 35628230 PMCID: PMC9141980 DOI: 10.3390/ijms23105421] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Revised: 05/11/2022] [Accepted: 05/11/2022] [Indexed: 02/05/2023] Open
Abstract
Amyloid fibril formation is associated with several amyloidoses, including neurodegenerative Alzheimer's or Parkinson's diseases. The process of such fibrillar structure formation is still not fully understood, with new mechanistic insights appearing on a regular basis. This, in turn, has limited the development of potential anti-amyloid compounds, with only a handful of effective cures or treatment modalities available. One of the multiple amyloid aggregation factors that requires further examination is the ability of proteins to form multiple, structurally distinct aggregates, based on the environmental conditions. In this work, we examine how the initial folding state affects the fibrilization of lysozyme-an amyloidogenic protein, often used in protein aggregation studies. We show that there is a correlation between the initial state of the protein and the aggregate formation lag time, rate of elongation, resulting aggregate structural variability and dye-binding properties, as well as formation lag time and rate of elongation.
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Affiliation(s)
- Kamile Mikalauskaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania
| | - Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania
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8
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Matiiv AB, Trubitsina NP, Matveenko AG, Barbitoff YA, Zhouravleva GA, Bondarev SA. Structure and Polymorphism of Amyloid and Amyloid-Like Aggregates. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:450-463. [PMID: 35790379 DOI: 10.1134/s0006297922050066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 04/08/2022] [Accepted: 04/09/2022] [Indexed: 06/15/2023]
Abstract
Amyloids are protein aggregates with the cross-β structure. The interest in amyloids is explained, on the one hand, by their role in the development of socially significant human neurodegenerative diseases, and on the other hand, by the discovery of functional amyloids, whose formation is an integral part of cellular processes. To date, more than a hundred proteins with the amyloid or amyloid-like properties have been identified. Studying the structure of amyloid aggregates has revealed a wide variety of protein conformations. In the review, we discuss the diversity of protein folds in the amyloid-like aggregates and the characteristic features of amyloid aggregates that determine their unusual properties, including stability and interaction with amyloid-specific dyes. The review also describes the diversity of amyloid aggregates and its significance for living organisms.
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Affiliation(s)
- Anton B Matiiv
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Nina P Trubitsina
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Andrew G Matveenko
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Yury A Barbitoff
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
- Bioinformatics Institute, Saint Petersburg, 197342, Russia
| | - Galina A Zhouravleva
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
- Laboratory of Amyloid Biology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
| | - Stanislav A Bondarev
- Department of Genetics and Biotechnology, Saint Petersburg State University, Saint Petersburg, 199034, Russia.
- Laboratory of Amyloid Biology, Saint Petersburg State University, Saint Petersburg, 199034, Russia
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9
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Ziaunys M, Sakalauskas A, Mikalauskaite K, Smirnovas V. Polymorphism of Alpha-Synuclein Amyloid Fibrils Depends on Ionic Strength and Protein Concentration. Int J Mol Sci 2021; 22:12382. [PMID: 34830264 PMCID: PMC8621411 DOI: 10.3390/ijms222212382] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/20/2022] Open
Abstract
Protein aggregate formation is linked with multiple amyloidoses, including Alzheimer's and Parkinson's diseases. Currently, the understanding of such fibrillar structure formation and propagation is still not sufficient, the outcome of which is a lack of potent, anti-amyloid drugs. The environmental conditions used during in vitro protein aggregation assays play an important role in determining both the aggregation kinetic parameters, as well as resulting fibril structure. In the case of alpha-synuclein, ionic strength has been shown as a crucial factor in its amyloid aggregation. In this work, we examine a large sample size of alpha-synuclein aggregation reactions under thirty different ionic strength and protein concentration combinations and determine the resulting fibril structural variations using their dye-binding properties, secondary structure and morphology. We show that both ionic strength and protein concentration determine the structural variability of alpha-synuclein amyloid fibrils and that sometimes even identical conditions can result in up to four distinct types of aggregates.
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Affiliation(s)
- Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Centre, Vilnius University, 10257 Vilnius, Lithuania; (A.S.); (K.M.); (V.S.)
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10
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Ziaunys M, Mikalauskaite K, Sakalauskas A, Smirnovas V. Interplay between epigallocatechin-3-gallate and ionic strength during amyloid aggregation. PeerJ 2021; 9:e12381. [PMID: 34733592 PMCID: PMC8544251 DOI: 10.7717/peerj.12381] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/04/2021] [Indexed: 01/04/2023] Open
Abstract
The formation and accumulation of protein amyloid aggregates is linked with multiple amyloidoses, including neurodegenerative Alzheimer's or Parkinson's disease. The mechanism of such fibril formation is impacted by various environmental conditions, which greatly complicates the search for potential anti-amyloid compounds. One of these factors is solution ionic strength, which varies between different aggregation protocols during in vitro drug screenings. In this work, we examine the interplay between ionic strength and a well-known protein aggregation inhibitor-epigallocatechin-3-gallate. We show that changes in solution ionic strength have a major impact on the compound's inhibitory effect, reflected in both aggregation times and final fibril structure. We also observe that this effect is unique to different amyloid-forming proteins, such as insulin, alpha-synuclein and amyloid-beta.
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Affiliation(s)
- Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Kamile Mikalauskaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Andrius Sakalauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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11
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Sakalauskas A, Ziaunys M, Snieckute R, Smirnovas V. Autoxidation Enhances Anti-Amyloid Potential of Flavone Derivatives. Antioxidants (Basel) 2021; 10:antiox10091428. [PMID: 34573060 PMCID: PMC8465893 DOI: 10.3390/antiox10091428] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 08/31/2021] [Accepted: 09/01/2021] [Indexed: 02/07/2023] Open
Abstract
The increasing prevalence of amyloid-related disorders, such as Alzheimer's or Parkinson's disease, raises the need for effective anti-amyloid drugs. It has been shown on numerous occasions that flavones, a group of naturally occurring anti-oxidants, can impact the aggregation process of several amyloidogenic proteins and peptides, including amyloid-beta. Due to flavone autoxidation at neutral pH, it is uncertain if the effective inhibitor is the initial molecule or a product of this reaction, as many anti-amyloid assays attempt to mimic physiological conditions. In this work, we examine the aggregation-inhibiting properties of flavones before and after they are oxidized. The oxidation of flavones was monitored by measuring the UV-vis absorbance spectrum change over time. The protein aggregation kinetics were followed by measuring the amyloidophilic dye thioflavin-T (ThT) fluorescence intensity change. Atomic force microscopy was employed to image the aggregates formed with the most prominent inhibitors. We demonstrate that flavones, which undergo autoxidation, have a far greater potency at inhibiting the aggregation of both the disease-related amyloid-beta, as well as a model amyloidogenic protein-insulin. Oxidized 6,2',3'-trihydroxyflavone was the most potent inhibitor affecting both insulin (7-fold inhibition) and amyloid-beta (2-fold inhibition). We also show that this tendency to autoxidize is related to the positions of the flavone hydroxyl groups.
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12
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Fridmanis J, Toleikis Z, Sneideris T, Ziaunys M, Bobrovs R, Smirnovas V, Jaudzems K. Aggregation Condition-Structure Relationship of Mouse Prion Protein Fibrils. Int J Mol Sci 2021; 22:9635. [PMID: 34502545 PMCID: PMC8431800 DOI: 10.3390/ijms22179635] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/02/2021] [Accepted: 09/03/2021] [Indexed: 11/16/2022] Open
Abstract
Prion diseases are associated with conformational conversion of cellular prion protein into a misfolded pathogenic form, which resembles many properties of amyloid fibrils. The same prion protein sequence can misfold into different conformations, which are responsible for variations in prion disease phenotypes (prion strains). In this work, we use atomic force microscopy, FTIR spectroscopy and magic-angle spinning NMR to devise structural models of mouse prion protein fibrils prepared in three different denaturing conditions. We find that the fibril core region as well as the structure of its N- and C-terminal parts is almost identical between the three fibrils. In contrast, the central part differs in length of β-strands and the arrangement of charged residues. We propose that the denaturant ionic strength plays a major role in determining the structure of fibrils obtained in a particular condition by stabilizing fibril core interior-facing glutamic acid residues.
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Affiliation(s)
- Jēkabs Fridmanis
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006 Riga, Latvia; (J.F.); (Z.T.); (R.B.)
| | - Zigmantas Toleikis
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006 Riga, Latvia; (J.F.); (Z.T.); (R.B.)
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania; (T.S.); (M.Z.); (V.S.)
| | - Tomas Sneideris
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania; (T.S.); (M.Z.); (V.S.)
| | - Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania; (T.S.); (M.Z.); (V.S.)
| | - Raitis Bobrovs
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006 Riga, Latvia; (J.F.); (Z.T.); (R.B.)
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, LT-10257 Vilnius, Lithuania; (T.S.); (M.Z.); (V.S.)
| | - Kristaps Jaudzems
- Department of Physical Organic Chemistry, Latvian Institute of Organic Synthesis, Aizkraukles 21, LV-1006 Riga, Latvia; (J.F.); (Z.T.); (R.B.)
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13
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Temperature-Dependent Structural Variability of Prion Protein Amyloid Fibrils. Int J Mol Sci 2021; 22:ijms22105075. [PMID: 34064883 PMCID: PMC8151363 DOI: 10.3390/ijms22105075] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/07/2021] [Accepted: 05/09/2021] [Indexed: 12/20/2022] Open
Abstract
Prion protein aggregation into amyloid fibrils is associated with the onset and progression of prion diseases—a group of neurodegenerative amyloidoses. The process of such aggregate formation is still not fully understood, especially regarding their polymorphism, an event where the same type of protein forms multiple, conformationally and morphologically distinct structures. Considering that such structural variations can greatly complicate the search for potential antiamyloid compounds, either by having specific propagation properties or stability, it is important to better understand this aggregation event. We have recently reported the ability of prion protein fibrils to obtain at least two distinct conformations under identical conditions, which raised the question if this occurrence is tied to only certain environmental conditions. In this work, we examined a large sample size of prion protein aggregation reactions under a range of temperatures and analyzed the resulting fibril dye-binding, secondary structure and morphological properties. We show that all temperature conditions lead to the formation of more than one fibril type and that this variability may depend on the state of the initial prion protein molecules.
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14
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Hadi Alijanvand S, Peduzzo A, Buell AK. Secondary Nucleation and the Conservation of Structural Characteristics of Amyloid Fibril Strains. Front Mol Biosci 2021; 8:669994. [PMID: 33937341 PMCID: PMC8085410 DOI: 10.3389/fmolb.2021.669994] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 03/30/2021] [Indexed: 12/17/2022] Open
Abstract
Amyloid fibrils are ordered protein aggregates and a hallmark of many severe neurodegenerative diseases. Amyloid fibrils form through primary nucleation from monomeric protein, grow through monomer addition and proliferate through fragmentation or through the nucleation of new fibrils on the surface of existing fibrils (secondary nucleation). It is currently still unclear how amyloid fibrils initially form in the brain of affected individuals and how they are amplified. A given amyloid protein can sometimes form fibrils of different structure under different solution conditions in vitro, but often fibrils found in patients are highly homogeneous. These findings suggest that the processes that amplify amyloid fibrils in vivo can in some cases preserve the structural characteristics of the initial seed fibrils. It has been known for many years that fibril growth by monomer addition maintains the structure of the seed fibril, as the latter acts as a template that imposes its fold on the newly added monomer. However, for fibrils that are formed through secondary nucleation it was, until recently, not clear whether the structure of the seed fibril is preserved. Here we review the experimental evidence on this question that has emerged over the last years. The overall picture is that the fibril strain that forms through secondary nucleation is mostly defined by the solution conditions and intrinsic structural preferences, and not by the seed fibril strain.
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Affiliation(s)
- Saeid Hadi Alijanvand
- Bioprocess Engineering Department, Institute of Industrial and Environmental Biotechnology, National Institute of Genetic Engineering and Biotechnology, Tehran, Iran
| | - Alessia Peduzzo
- Technical University of Denmark, Department of Biotechnology and Biomedicine, Lyngby, Denmark
| | - Alexander K. Buell
- Technical University of Denmark, Department of Biotechnology and Biomedicine, Lyngby, Denmark
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15
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Lysozyme Fibrils Alter the Mechanism of Insulin Amyloid Aggregation. Int J Mol Sci 2021; 22:ijms22041775. [PMID: 33579016 PMCID: PMC7916790 DOI: 10.3390/ijms22041775] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/06/2021] [Accepted: 02/08/2021] [Indexed: 12/30/2022] Open
Abstract
Protein aggregation into amyloid fibrils is linked to multiple disorders. The understanding of how natively non-harmful proteins convert to these highly cytotoxic amyloid aggregates is still not sufficient, with new ideas and hypotheses being presented each year. Recently it has been shown that more than one type of protein aggregates may co-exist in the affected tissue of patients suffering from amyloid-related disorders, sparking the idea that amyloid aggregates formed by one protein may induce another protein’s fibrillization. In this work, we examine the effect that lysozyme fibrils have on insulin amyloid aggregation. We show that not only do lysozyme fibrils affect insulin nucleation, but they also alter the mechanism of its aggregation.
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16
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Ziaunys M, Sakalauskas A, Mikalauskaite K, Smirnovas V. Exploring the occurrence of thioflavin-T-positive insulin amyloid aggregation intermediates. PeerJ 2021; 9:e10918. [PMID: 33614299 PMCID: PMC7881721 DOI: 10.7717/peerj.10918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/18/2021] [Indexed: 12/12/2022] Open
Abstract
The aggregation of proteins is considered to be the main cause of several neurodegenerative diseases. Despite much progress in amyloid research, the process of fibrillization is still not fully understood, which is one of the main reasons why there are still very few effective treatments available. When the aggregation of insulin, a model amyloidogenic protein, is tracked using thioflavin-T (ThT), an amyloid specific dye, there is an anomalous occurrence of double-sigmoidal aggregation kinetics. Such an event is likely related to the formation of ThT-positive intermediates, which may affect the outcome of both aggregation kinetic data, as well as final fibril structure. In this work we explore insulin fibrillization under conditions, where both normal and double-sigmoidal kinetics are observed and show that, despite their dye-binding properties and random occurrence, the ThT-positive intermediates do not significantly alter the overall aggregation process.
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Affiliation(s)
- Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Andrius Sakalauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Kamile Mikalauskaite
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania
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17
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Effect of Ionic Strength on Thioflavin-T Affinity to Amyloid Fibrils and Its Fluorescence Intensity. Int J Mol Sci 2020; 21:ijms21238916. [PMID: 33255444 PMCID: PMC7727833 DOI: 10.3390/ijms21238916] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 11/23/2020] [Accepted: 11/24/2020] [Indexed: 12/12/2022] Open
Abstract
The formation of amyloid fibrils is linked to multiple neurodegenerative disorders, including Alzheimer’s and Parkinson’s disease. Despite years of research and countless studies on the topic of such aggregate formation, as well as their resulting structure, the current knowledge is still fairly limited. One of the main aspects prohibiting effective aggregation tracking is the environment’s effect on amyloid-specific dyes, namely thioflavin-T (ThT). Currently, there are only a few studies hinting at ionic strength being one of the factors that modulate the dye’s binding affinity and fluorescence intensity. In this work we explore this effect under a range of ionic strength conditions, using insulin, lysozyme, mouse prion protein, and α-synuclein fibrils. We show that ionic strength is an extremely important factor affecting both the binding affinity, as well as the fluorescence intensity of ThT.
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18
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Ziaunys M, Sakalauskas A, Smirnovas V. Identifying Insulin Fibril Conformational Differences by Thioflavin-T Binding Characteristics. Biomacromolecules 2020; 21:4989-4997. [PMID: 33201685 PMCID: PMC7739267 DOI: 10.1021/acs.biomac.0c01178] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
![]()
Amyloidogenic
protein aggregation into highly structured fibrils
is linked to more than 30 amyloidoses, including several neurodegenerative
disorders. Despite significant progress in trying to understand the
process of amyloid formation, there is still no cure or effective
treatment available. A number of studies involving potential anti-amyloid
compounds rely on the use of a fluorescent probe—thioflavin-T—to
track the appearance, growth, or disassembly of these cytotoxic aggregates.
Despite the wide application of this dye molecule, its interaction
with amyloid fibrils is still poorly understood. Recent reports have
shown it may possess distinct binding modes and fluorescence intensities
based on the conformation of the examined fibrils. In this work, we
generate insulin fibrils under four different conditions and attempt
to identify distinct conformations using both classic methods, such
as atomic force microscopy and Fourier-transform infrared spectroscopy,
as well as their ThT binding ability and fluorescence quantum yield.
We show that there is a significant variance of ThT fluorescence quantum
yields, excitation/emission maxima positions, and binding modes between
distinct insulin fibril conformations.
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Affiliation(s)
- Mantas Ziaunys
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio al. 7, Vilnius LT-10257, Lithuania
| | - Andrius Sakalauskas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio al. 7, Vilnius LT-10257, Lithuania
| | - Vytautas Smirnovas
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Sauletekio al. 7, Vilnius LT-10257, Lithuania
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19
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Self-Replication of Prion Protein Fragment 89-230 Amyloid Fibrils Accelerated by Prion Protein Fragment 107-143 Aggregates. Int J Mol Sci 2020; 21:ijms21197410. [PMID: 33049945 PMCID: PMC7583978 DOI: 10.3390/ijms21197410] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 10/02/2020] [Accepted: 10/03/2020] [Indexed: 12/15/2022] Open
Abstract
Prion protein amyloid aggregates are associated with infectious neurodegenerative diseases, known as transmissible spongiform encephalopathies. Self-replication of amyloid structures by refolding of native protein molecules is the probable mechanism of disease transmission. Amyloid fibril formation and self-replication can be affected by many different factors, including other amyloid proteins and peptides. Mouse prion protein fragments 107-143 (PrP(107-143)) and 89-230 (PrP(89-230)) can form amyloid fibrils. β-sheet core in PrP(89-230) amyloid fibrils is limited to residues ∼160-220 with unstructured N-terminus. We employed chemical kinetics tools, atomic force microscopy and Fourier-transform infrared spectroscopy, to investigate the effects of mouse prion protein fragment 107-143 fibrils on the aggregation of PrP(89-230). The data suggest that amyloid aggregates of a short prion-derived peptide are not able to seed PrP(89-230) aggregation; however, they accelerate the self-replication of PrP(89-230) amyloid fibrils. We conclude that PrP(107-143) fibrils could facilitate the self-replication of PrP(89-230) amyloid fibrils in several possible ways, and that this process deserves more attention as it may play an important role in amyloid propagation.
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20
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Sakalauskas A, Ziaunys M, Smirnovas V. Gallic acid oxidation products alter the formation pathway of insulin amyloid fibrils. Sci Rep 2020; 10:14466. [PMID: 32879381 PMCID: PMC7468289 DOI: 10.1038/s41598-020-70982-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Accepted: 08/05/2020] [Indexed: 12/25/2022] Open
Abstract
Amyloidogenic protein assembly into insoluble fibrillar aggregates is linked with several neurodegenerative disorders, such as Alzheimer’s or Parkinson’s disease, affecting millions of people worldwide. The search for a potential anti-amyloid drug has led to the discovery of hundreds of compounds, none of which have passed all clinical trials. Gallic acid has been shown to both modulate factors leading to the onset of neurodegenerative disorders, as well as directly inhibit amyloid formation. However, the conditions under which this effect is seen could lead to oxidation of this polyphenol, likely changing its properties. Here we examine the effect of gallic acid and its oxidised form on the aggregation of a model amyloidogenic protein–insulin at low pH conditions. We show a vastly higher inhibitory potential of the oxidised form, as well as an alteration in the aggregation pathway, leading to the formation of a specific fibril conformation.
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Affiliation(s)
- Andrius Sakalauskas
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, 10257, Vilnius, Lithuania
| | - Mantas Ziaunys
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, 10257, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Life Sciences Center, Institute of Biotechnology, Vilnius University, Sauletekio al. 7, 10257, Vilnius, Lithuania.
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21
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Peduzzo A, Linse S, Buell AK. The Properties of α-Synuclein Secondary Nuclei Are Dominated by the Solution Conditions Rather than the Seed Fibril Strain. ACS Chem Neurosci 2020; 11:909-918. [PMID: 32069013 DOI: 10.1021/acschemneuro.9b00594] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Amyloid fibrils of α-synuclein (α-syn) are a component of Lewy bodies, the characteristic hallmark of Parkinson's disease. Amyloid fibrils arise through primary nucleation from monomers, which in the case of α-syn is often heterogeneous, followed by the growth of the nuclei by monomer addition. Secondary nucleation corresponds to the formation of new fibrils facilitated by pre-existing fibrils. While it is well-established that the newly added monomer in fibril elongation adopts the conformation of the monomers in the seed ("templating"), it is unclear whether fibrils formed through secondary nucleation of monomers on the surface of seed fibrils copy the structure of the "parent" fibril. Here we show by biochemical and microscopical methods that the secondary nucleation of α-syn, enabled at mildly acidic pH, leads to fibrils that structurally resemble more closely those formed de novo under the same conditions, rather than the seeds if these are formed under different solution conditions. This result has important implications for the mechanistic understanding of the secondary nucleation of amyloid fibrils and its role in the propagation of aggregate pathology in protein misfolding diseases.
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Affiliation(s)
- Alessia Peduzzo
- Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany
| | - Sara Linse
- Department of Biochemistry and Structural Biology, Centre for Molecular Protein Science, Lund University, SE-221 00 Lund, Sweden
| | - Alexander K. Buell
- Institute of Physical Biology, Heinrich-Heine University, 40225 Düsseldorf, Germany
- Technical University of Denmark, Department of Biotechnology and Biomedicine, 2800 Lyngby, Denmark
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22
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Yuzu K, Lindgren M, Nyström S, Zhang J, Mori W, Kunitomi R, Nagase T, Iwaya K, Hammarström P, Zako T. Insulin amyloid polymorphs: implications for iatrogenic cytotoxicity. RSC Adv 2020; 10:37721-37727. [PMID: 35515176 PMCID: PMC9057202 DOI: 10.1039/d0ra07742a] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 10/05/2020] [Indexed: 12/15/2022] Open
Abstract
Amyloid specific fluorescent probes are becoming an important tool for studies of disease progression and conformational polymorphisms in diseases related to protein misfolding and aggregation such as localized and systemic amyloidosis. Herein, it is demonstrated that using the amyloid specific fluorescent probes pFTAA and benzostyryl capped benzothiadiazole BTD21, structural polymorphisms of insulin amyloids are imaged in localized insulin-derived amyloid aggregates formed at subcutaneous insulin-injection sites in patients with diabetes. It is also found that pFTAA and BTD21 could discriminate structural polymorphisms of insulin amyloids, so called fibrils and filaments, formed in vitro. In addition, it is shown that insulin drug preparations used for treating diabetes formed various types of amyloid aggregates that can be assessed and quantified using pFTAA and BTD21. Interestingly, incubated pFTAA-positive insulin preparation aggregates show cytotoxicity while BTD21-positive aggregates are less toxic. From these observations, a variety of amyloid polymorphic structures with different cytotoxicities formed both in vivo and in vitro by various insulin preparations are proposed. Structural polymorphism of insulin amyloids in vivo can be recognized using novel amyloid specific fluorescent probes, pFTAA and BTD21.![]()
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Affiliation(s)
- Keisuke Yuzu
- Department of Chemistry and Biology
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
| | - Mikael Lindgren
- Department of Physics
- Faculty of Natural Sciences
- Norwegian University of Science and Technology
- NO-7491 Trondheim
- Norway
| | - Sofie Nyström
- IFM Chemistry
- Linköping University
- SE-58183 Linköping
- Sweden
| | - Jun Zhang
- IFM Chemistry
- Linköping University
- SE-58183 Linköping
- Sweden
| | - Wakako Mori
- Department of Chemistry and Biology
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
| | - Risako Kunitomi
- Department of Chemistry and Biology
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
| | - Terumasa Nagase
- Department of Metabolism and Endocrinology
- Tokyo Medical University Ibaraki Medical Center
- Japan
| | - Keiichi Iwaya
- Department of Pathology
- Sasaki Institute
- Kyoundo Hospital
- Tokyo 101-0062
- Japan
| | | | - Tamotsu Zako
- Department of Chemistry and Biology
- Graduate School of Science and Engineering
- Ehime University
- Matsuyama
- Japan
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