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Mishra R, Gerlach GJ, Sahoo B, Camacho CJ, Wetzel R. A Targetable Self-association Surface of the Huntingtin exon1 Helical Tetramer Required for Assembly of Amyloid Pre-nucleation Oligomers. J Mol Biol 2024; 436:168607. [PMID: 38734203 DOI: 10.1016/j.jmb.2024.168607] [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: 12/13/2023] [Revised: 05/03/2024] [Accepted: 05/06/2024] [Indexed: 05/13/2024]
Abstract
Polyglutamine (polyQ) sequences undergo repeat-length dependent formation of disease-associated, amyloid-like cross-β core structures with kinetics and aggregate morphologies often influenced by the flanking sequences. In Huntington's disease (HD), the httNT segment on the polyQ's N-terminal flank enhances aggregation rates by changing amyloid nucleation from a classical homogeneous mechanism to a two-step process requiring an ɑ-helix-rich oligomeric intermediate. A folded, helix-rich httNT tetrameric structure suggested to be this critical intermediate was recently reported. Here we employ single alanine replacements along the httNT sequence to assess this proposed structure and refine the mechanistic model. We find that Ala replacement of hydrophobic residues within simple httNT peptides greatly suppresses helicity, supporting the tetramer model. These same helix-disruptive replacements in the httNT segment of an exon-1 analog greatly reduce aggregation kinetics, suggesting that an ɑ-helix rich multimer - either the tetramer or a larger multimer - plays an on-pathway role in nucleation. Surprisingly, several other Ala replacements actually enhance helicity and/or amyloid aggregation. The spatial localization of these residues on the tetramer surface suggests a self-association interface responsible for formation of the octomers and higher-order multimers most likely required for polyQ amyloid nucleation. Multimer docking of the tetramer, using the protein-protein docking algorithm ClusPro, predicts this symmetric surface to be a viable tetramer dimerization interface. Intriguingly, octomer formation brings the emerging polyQ chains into closer proximity at this tetramer-tetramer interface. Further supporting the potential importance of tetramer super-assembly, computational docking with a known exon-1 aggregation inhibitor predicts ligand contacts with residues at this interface.
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Affiliation(s)
- Rakesh Mishra
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Gabriella J Gerlach
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA
| | - Bankanidhi Sahoo
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Carlos J Camacho
- Department of Computational and Systems Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
| | - Ronald Wetzel
- Department Structural Biology, University of Pittsburgh School of Medicine Pittsburgh, PA 15260, USA.
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2
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Prajapati KP, Mittal S, Ansari M, Mahato OP, Bharati S, Singh AP, Ahlawat S, Tiku AB, Anand BG, Kar K. Pleiotropic Nanostructures Built from l-Histidine Show Biologically Relevant Multicatalytic Activities. ACS APPLIED MATERIALS & INTERFACES 2024; 16:18268-18284. [PMID: 38564419 DOI: 10.1021/acsami.3c14606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The essential amino acid histidine plays a central role in the manifestation of several metabolic processes, including protein synthesis, enzyme-catalysis, and key biomolecular interactions. However, excess accumulation of histidine causes histidinemia, which shows brain-related medical complications, and the molecular mechanism of such histidine-linked complications is largely unknown. Here, we show that histidine undergoes a self-assembly process, leading to the formation of amyloid-like cytotoxic and catalytically active nanofibers. The kinetics of histidine self-assembly was favored in the presence of Mg(II) and Co(II) ions. Molecular dynamics data showed that preferential noncovalent interactions dominated by H-bonds between histidine molecules facilitate the formation of histidine nanofibers. The histidine nanofibers induced amyloid cross-seeding reactions in several proteins and peptides including pathogenic Aβ1-42 and brain extract components. Further, the histidine nanofibers exhibited oxidase activity and enhanced the oxidation of neurotransmitters. Cell-based studies confirmed the cellular internalization of histidine nanofibers in SH-SY5Y cells and subsequent cytotoxic effects through necrosis and apoptosis-mediated cell death. Since several complications including behavioral abnormality, developmental delay, and neurological disabilities are directly linked to abnormal accumulation of histidine, our findings provide a foundational understanding of the mechanism of histidine-related complications. Further, the ability of histidine nanofibers to catalyze amyloid seeding and oxidation reactions is equally important for both biological and materials science research.
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Affiliation(s)
- Kailash Prasad Prajapati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Shikha Mittal
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Om Prakash Mahato
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Shikha Bharati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Akhilesh Pratap Singh
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Shobha Ahlawat
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ashu Bhan Tiku
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Bibin Gnanadhason Anand
- Biomolecular Self-Assembly Lab, Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu 603203, India
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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Prajapati KP, Ansari M, Mittal S, Anand BG, Kar K. Initiation of Brain Extract Fibrillation and Effective Cellular Internalization of Tryptophan Fibrils Unveils Its Neurotoxicity Risk. ACS Chem Neurosci 2023; 14:4274-4281. [PMID: 37962955 DOI: 10.1021/acschemneuro.3c00367] [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] [Indexed: 11/16/2023] Open
Abstract
Recent discoveries on the self-assembly of aromatic amino acids into amyloid-like neurotoxic nanostructures have initiated a quest to decode the molecular mechanisms for the initiation of neurodegeneration. Moreover, the multicomponent nature of the amyloid deposits still questions the existing and well-defined amyloid cascade hypothesis. Hence, deciphering the neurotoxicity of amyloid-like nanostructures of aromatic amino acids becomes crucial for understanding the etiology of amyloidogenesis. Here, we demonstrate the cellular internalization and consequential damaging effects of self-assembled amyloid-like tryptophan nanostructures on human neuroblastoma cells. The cell-damaging potential of tryptophan nanostructure seems to be facilitated via ROS generation, necrosis and apoptosis mediated cell death. Further, tryptophan nanostructures were found to be seeding competent conformers, which triggered aggressive aggregation of brain extract components. The early stage intermediate nanostructures possess a higher cross-seeding efficacy than the seeding potential of the matured tryptophan fibrils. In addition to the cell-damaging and cross-seeding effects, tryptophan fibrils were found to catalyze oxidation of neuromodulator dopamine. These findings add more insights into the specific role of tryptophan self-assembly during the pathogenesis of hypertryptophanemia and other amyloid-associated neurodegenerative complications.
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Affiliation(s)
- Kailash Prasad Prajapati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Shikha Mittal
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Bibin Gnanadhason Anand
- Biomolecular Self-Assembly Lab, Department of Biotechnology, School of Bioengineering, SRM Institute of Science and Technology, Kattankulathur, Tamil Nadu 603203, India
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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4
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Prajapati KP, Ansari M, Yadav DK, Mittal S, Anand BG, Kar K. A robust yet simple method to generate fluorescent amyloid nanofibers. J Mater Chem B 2023; 11:8765-8774. [PMID: 37661927 DOI: 10.1039/d3tb01203d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Covalent tagging of fluorophores is central to the mechanistic understanding of important biological processes including protein-protein interaction and protein aggregation. Hence, studies on fluorophore-tagged peptides help in elucidating the molecular mechanism of amyloidogenesis, its cellular internalization, and crosstalk potential. Despite the many advantages the covalently tagged proteins offer, difficulties such as expensive and tedious synthesis and purification protocols have become a matter of concern. Importantly, covalently tagged fluorophores could introduce structural constraints, which may influence the conformation of the monomeric and aggregated forms of proteins. Here, we describe a robust-yet-simple method to make fluorescent-amyloid nanofibers through a coassembly-reaction route that does not alter the aggregation kinetics and the characteristic β-sheet-conformers of resultant nanofibers. Fluorescent amyloid nanofibers derived from insulin, lysozyme, Aβ1-42, and metabolites were successfully fabricated in our study. Importantly, the incorporated fluorophores exhibited remarkable stability, remaining intact without leaching even after undergoing serial dilutions and prolonged storage periods. This method enables monitoring of cellular internalization of the fluorescent-amyloid-nanofibers and the detection of FRET-signals during interfibrillar interactions. This simple and affordable protocol may significantly help amyloid researchers working on both in vitro and animal models.
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Affiliation(s)
- Kailash Prasad Prajapati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Deepak Kumar Yadav
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Shikha Mittal
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Bibin Gnanadhason Anand
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, 110067, India.
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Autooxidation of curcumin in physiological buffer causes an enhanced synergistic anti-amyloid effect. Int J Biol Macromol 2023; 235:123629. [PMID: 36773869 DOI: 10.1016/j.ijbiomac.2023.123629] [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: 10/18/2022] [Revised: 12/27/2022] [Accepted: 02/06/2023] [Indexed: 02/11/2023]
Abstract
Curcumin is an important food additive that shows multiple medical-benefits including anticarcinogenic, anti-inflammatory, antibiotic and antiamyloid properties. However, understanding the mechanism of curcumin-mediated effects becomes rather complicated since it has low bio-viability and it undergoes autooxidation, influenced by temperature, pH and buffer. We find that curcumin's antiamyloid-potential is not primarily due to curcumin alone, rather due to a synergistic action of curcumin and its autooxidized-products generated during inhibition reactions. In physiological buffer curcumin undergoes thermally induced autooxidation and yields stable compounds which can synergistically work for both inhibition of amyloid aggregation and promotion of amyloid-disaggregation into soluble protein species. Curcumin also showed substantial inhibition effect against coaggregation of different food proteins. Curcumin's strong affinity for the hydrophobic moieties of the aggregation-prone partially-folded insulin structures seems crucial for the inhibition mechanism. Further, autooxidized curcumin products were found to protect UV-induced protein damage. The results provide conceptual foundations highlighting the link between chemistry and antiamyloid-activity of curcumin and may inspire curcumin-based therapeutics against amyloidogenesis.
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Prajapati KP, Anand BG, Ansari M, Tiku AB, Kar K. Tryptophan self-assembly yields cytotoxic nanofibers containing amyloid-mimicking and cross-seeding competent conformers. NANOSCALE 2022; 14:16270-16285. [PMID: 36300424 DOI: 10.1039/d2nr03544h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Dietary consumption of Trp via protein-based foods is essential for the maintenance of crucial metabolic processes including the synthesis of proteins and several vital metabolites such as serotonin, melatonin, acetyl CoA, and NADP. However, the abnormal build-up of Trp is known to cause familial hypertryptophanemia and several brain-related medical complications. The molecular mechanism of the onset of such Trp-driven health issues is largely unknown. Here, we show that Trp, under the physiologically mimicked conditions of temperature and buffer, undergoes a concentration driven self-assembly process, yielding amyloid-mimicking nanofibers. Viable H-bonds, π-π interactions and hydrophobic contacts between optimally coordinated Trp molecules become important factors for the formation of a Trp nanoassembly that displays a hydrophobic exterior and a hydrophilic interior. Importantly, Trp nanofibers were found to possess high affinity for native proteins, and they act as cross-seeding competent conformers capable of nucleating amyloid formation in globular proteins including whey protein β-lactoglobulin and type II diabetes linked insulin hormone. Moreover, these amyloid mimicking Trp nanostructures showed toxic effects on neuroblastoma cells. Since the key symptoms in hypertryptophanemia such as behavioural defects and brain-damaging oxidative stress are also observed in amyloid related disorders, our findings on amyloid-like Trp-nanofibers may help in the mechanistic understanding of Trp-related complications and these findings are equally important for innovation in applied nanomaterials design and strategies.
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Affiliation(s)
- Kailash Prasad Prajapati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Bibin Gnanadhason Anand
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Ashu Bhan Tiku
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
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7
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Significance of native PLGA nanoparticles in the treatment of Alzheimer's disease pathology. Bioact Mater 2022; 17:506-525. [PMID: 36330076 PMCID: PMC9614411 DOI: 10.1016/j.bioactmat.2022.05.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 04/26/2022] [Accepted: 05/23/2022] [Indexed: 02/07/2023] Open
Abstract
Alzheimer's disease (AD) is believed to be triggered by increased levels/aggregation of β-amyloid (Aβ) peptides. At present, there is no effective disease-modifying treatment for AD. Here, we evaluated the therapeutic potential of FDA-approved native poly(d,l-lactide-co-glycolide) (PLGA) nanoparticles on Aβ aggregation and in cellular/animal models of AD. Our results showed that native PLGA can not only suppress the spontaneous aggregation but can also trigger disassembly of preformed Aβ aggregates. Spectroscopic studies, molecular dynamics simulations and biochemical analyses revealed that PLGA, by interacting with the hydrophobic domain of Aβ1-42, prevents a conformational shift towards the β-sheet structure, thus precluding the formation and/or triggering disassembly of Aβ aggregates. PLGA-treated Aβ samples can enhance neuronal viability by reducing phosphorylation of tau protein and its associated signaling mechanisms. Administration of PLGA can interact with Aβ aggregates and attenuate memory deficits as well as Aβ levels/deposits in the 5xFAD mouse model of AD. PLGA can also protect iPSC-derived neurons from AD patients against Aβ toxicity by decreasing tau phosphorylation. These findings provide unambiguous evidence that native PLGA, by targeting different facets of the Aβ axis, can have beneficial effects in mouse neurons/animal models as well as on iPSC-derived AD neurons - thus signifying its unique therapeutic potential in the treatment of AD pathology. PLGA nanoparticles by interacting with hydrophobic domain inhibit Aβ aggregation. PLGA-mediated inhibition of Aβ aggregation can increase viability of mouse neurons. PLGA administration can attenuate cognitive deficits/pathology in 5xFAD AD mouse model. PLGA can protect iPSC-derived neurons from AD patients against Aβ toxicity.
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8
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Buell AK. Stability matters, too - the thermodynamics of amyloid fibril formation. Chem Sci 2022; 13:10177-10192. [PMID: 36277637 PMCID: PMC9473512 DOI: 10.1039/d1sc06782f] [Citation(s) in RCA: 24] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2021] [Accepted: 01/30/2022] [Indexed: 12/26/2022] Open
Abstract
Amyloid fibrils are supramolecular homopolymers of proteins that play important roles in biological functions and disease. These objects have received an exponential increase in attention during the last few decades, due to their role in the aetiology of a range of severe disorders, most notably some of a neurodegenerative nature. While an overwhelming number of experimental studies exist that investigate how, and how fast, amyloid fibrils form and how their formation can be inhibited, a much more limited body of experimental work attempts to answer the question as to why these types of structures form (i.e. the thermodynamic driving force) and how stable they actually are. In this review, I attempt to give an overview of the types of experiments that have been performed to-date to answer these questions, and to summarise our current understanding of amyloid thermodynamics.
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Affiliation(s)
- Alexander K Buell
- Technical University of Denmark, Department of Biotechnology and Biomedicine Søltofts Plads, Building 227 2800 Kgs. Lyngby Denmark
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Prajapati KP, Anand BG, Ansari M, Temgire M, Tiku AB, Kar K. Amyloid-mimicking toxic nanofibers generated via self-assembly of dopamine. NANOSCALE 2022; 14:8649-8662. [PMID: 35667124 DOI: 10.1039/d1nr07741d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Molecular self-assembly of biologically relevant aromatic metabolites is known to generate cytotoxic nanostructures and this unique property has opened up new concepts in the molecular mechanisms of metabolite-linked disorders. Because aromaticity is intrinsic to the chemical structure of some important neuromodulators, the question of whether this property can promote their self-assembly into toxic higher order structures is highly relevant to the advancement of both fundamental and applied research. We show here that dopamine, an aromatic neuromodulator of high significance, undergoes self-assembly, under physiological buffer conditions, yielding cytotoxic supramolecular nanostructures. The oxidation of dopamine seems crucial in driving the self-assembly, and substantial inhibition effect was observed in the presence of antioxidants and acidic buffers. Strong H-bonds and π-π interactions between optimally-oriented dopamine molecules were found to stabilize the dopamine nanostructure which displayed characteristic β-structure-patterns with hydrophobic exterior and hydrophilic interior moieties. Furthermore, dopamine nanostructures were found to be highly toxic to human neuroblastoma cells, revealing apoptosis and necrosis-mediated cytotoxicity. Abnormal fluctuation in the dopamine concentration is known to predispose a multitude of neuronal complications, hence, the new findings of this study on oxidation-driven buildup of amyloid-mimicking neurotoxic dopamine assemblies may have direct relevance to the molecular origin of several dopamine related disorders.
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Affiliation(s)
| | | | - Masihuzzaman Ansari
- School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Mayur Temgire
- Department of Chemical Engineering, Indian Institution of Technology Bombay, Powai, Mumbai, 400076, India
| | - Ashu Bhan Tiku
- School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
| | - Karunakar Kar
- School of Life Sciences, Jawaharlal Nehru University, New Delhi-110067, India.
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Páníková T, Mitrová K, Halamová T, Mrzílková K, Pícha J, Chrudinová M, Kurochka A, Selicharová I, Žáková L, Jiráček J. Insulin Analogues with Altered Insulin Receptor Isoform Binding Specificities and Enhanced Aggregation Stabilities. J Med Chem 2021; 64:14848-14859. [PMID: 34591477 DOI: 10.1021/acs.jmedchem.1c01388] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Insulin is a lifesaver for millions of diabetic patients. There is a need for new insulin analogues with more physiological profiles and analogues that will be thermally more stable than human insulin. Here, we describe the chemical engineering of 48 insulin analogues that were designed to have changed binding specificities toward isoforms A and B of the insulin receptor (IR-A and IR-B). We systematically modified insulin at the C-terminus of the B-chain, at the N-terminus of the A-chain, and at A14 and A18 positions. We discovered an insulin analogue that has Cα-carboxyamidated Glu at B31 and Ala at B29 and that has a more than 3-fold-enhanced binding specificity in favor of the "metabolic" IR-B isoform. The analogue is more resistant to the formation of insulin fibrils at 37 °C and is also more efficient in mice than human insulin. Therefore, [AlaB29,GluB31,amideB31]-insulin may be interesting for further clinical evaluation.
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Affiliation(s)
- Terezie Páníková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
- Department of Biochemistry and Microbiology, University of Chemistry and Technology Prague, Technická 5, 166 28 Prague, Czech Republic
| | - Katarína Mitrová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Tereza Halamová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Karolína Mrzílková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Jan Pícha
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Martina Chrudinová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Andrii Kurochka
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Irena Selicharová
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Lenka Žáková
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
| | - Jiří Jiráček
- Institute of Organic Chemistry and Biochemistry, Czech Academy of Sciences, Flemingovo n. 2, 116 10 Prague 6, Czech Republic
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Anand BG, Prajapati KP, Ansari M, Yadav DK, Temgire M, Kar K. Genesis of Neurotoxic Hybrid Nanofibers from the Coassembly of Aromatic Amino Acids. ACS APPLIED MATERIALS & INTERFACES 2021; 13:36722-36736. [PMID: 34327979 DOI: 10.1021/acsami.1c04161] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Considering the relevance of accumulation and self-assembly of metabolites and aftermath of biological consequences, it is important to know whether they undergo coassembly and what properties the resultant hybrid higher-order structures would exhibit. This work reveals the inherent tendency of aromatic amino acids to undergo a spontaneous coassembly process under physiologically mimicked conditions, which yields neurotoxic hybrid nanofibers. Resultant hybrid nanostructures resembled the β-structured conformers stabilized by H-bonds and π-π stacking interactions, which were highly toxic to human neuroblastoma cells. The hybrid nanofibers also showed strong cross-seeding potential that triggered in vitro aggregation of diverse globular proteins and brain extract components, converting the native structures into cross-β-rich amyloid aggregates. The heterogenic nature of the hybrid nanofibers seems crucial for their higher toxicity and faster cross-seeding potential as compared to the homogeneous amino acid nanofibers. Our findings reveal the importance of aromaticity-driven optimized intermolecular arrangements for the coassembly of aromatic amino acids, and the results may provide important clues to the fundamental understanding of metabolite accumulation-related complications.
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Affiliation(s)
- Bibin Gnanadhason Anand
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Kailash Prasad Prajapati
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Deepak Kumar Yadav
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Mayur Temgire
- Department of Chemical Engineering, Indian Institution of Technology Bombay, Powai, Mumbai 400076, India
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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12
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Anand BG, Prajapati KP, Purohit S, Ansari M, Panigrahi A, Kaushik B, Behera RK, Kar K. Evidence of Anti-amyloid Characteristics of Plumbagin via Inhibition of Protein Aggregation and Disassembly of Protein Fibrils. Biomacromolecules 2021; 22:3692-3703. [PMID: 34375099 DOI: 10.1021/acs.biomac.1c00344] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The biological consequences associated with the conversion of soluble proteins into insoluble toxic amyloids are not only limited to the onset of neurodegenerative diseases but also to the potential health risks associated with supplements of protein therapeutic agents as well. Hence, finding inhibitors against amyloid formation is important, and natural product-based anti-amyloid compounds have gained much interest because of their higher efficacy and biocompatibility. Plumbagin has been identified as a potential natural product with multiple medical benefits; however, it remains largely unclear whether plumbagin can act against amyloid formation of proteins. Here, we show that plumbagin can effectively inhibit the temperature-induced amyloid aggregation of important proteins (insulin and serum albumin). Both experimental and computational data revealed that the presence of plumbagin in protein solutions, under aggregating conditions, promotes a direct protein-plumbagin interaction, which is predominantly stabilized by stronger H-bonds and hydrophobic interactions. Plumbagin-mediated retention of the native structures of proteins appears to play a crucial role in preventing their conversion into insoluble β-sheet-rich amyloid aggregates. More importantly, the addition of plumbagin into a suspension of protein fibrils triggered their spontaneous disassembly, promoting the release of soluble proteins. The results highlight that a possible synergistic effect via both the stabilization of protein structures and the restriction of the monomer recruitment at the fibril growth sites could be important for the mechanism of plumbagin's anti-aggregation effect. These findings may inspire the development of plumbagin-based formulations to benefit both the prevention and treatment of amyloid-related health complications.
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Affiliation(s)
- Bibin G Anand
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Kailash P Prajapati
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Sampreeta Purohit
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Masihuzzaman Ansari
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Ayoushna Panigrahi
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Bharti Kaushik
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Rajendra Kumar Behera
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | - Karunakar Kar
- Biophysical and Biomaterials Research Laboratory, Room 310, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
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13
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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: 22] [Impact Index Per Article: 5.5] [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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14
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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: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
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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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15
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Wetzel R. Exploding the Repeat Length Paradigm while Exploring Amyloid Toxicity in Huntington's Disease. Acc Chem Res 2020; 53:2347-2357. [PMID: 32975927 DOI: 10.1021/acs.accounts.0c00450] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Huntington's disease (HD) is a progressive, familial neurodegenerative disease triggered by the expansion of a polyglutamine (polyQ) track in the protein huntingtin (htt). PolyQ sequences up to Q36 in htt are not known to be toxic, while polyQ lengths above Q36 almost invariably lead to increased disease risk and decreased ages of onset. The large number of physical states (monomers, dimers, tetramers, non-β oligomers, nanofibrils, and clustered amyloid fibrils) on the self-association landscape, with their overlapping kinetics of formation, have greatly complicated identification of the molecular species responsible for HD toxicity, drawing attention to the need for innovative approaches.After reports of HD-associated intraneuronal htt inclusions in 1997, we elucidated aggregation mechanisms of both simple polyQ sequences and the more complex polyQ-containing "exon1" fragment of htt (htt-ex1). Grounded in this work, the more recent results described here were made possible by breakthroughs in the molecular design of diagnostic polyQ derivatives and in fluorescence applications for characterizing amyloid assembly intermediates. Thus, insertion of β-turn-promoting mutations into relatively short, disordered polyQ sequences created "pro-β-hairpin" polyQs (βHPs) that exhibit amyloid formation rates comparable to the enhanced rates seen with expanded polyQ peptides. Introduction of "β-breaker" mutations into these βHP polyQ sequences created molecules that are blocked from aggregating into amyloid and also can inhibit amyloid formation by other polyQ proteins. These mutational effects were then successfully transferred into more complex htt-ex1 sequence backgrounds. Insights into the aggregation properties of htt-ex1 derivatives-as well as into the nucleation process itself-were obtained using fluorescence correlation spectroscopy (FCS) and a novel thioflavin-T (ThT) protocol that allows quantitation of htt-ex1 assembly intermediates.Using these tools, we quantified physical states of htt-ex1 at different growth times in mammalian PC12 cells engineered for inducible expression of both normal and expanded polyQ repeat length versions of htt-ex1. For expanded polyQ versions, we found tetramers, oligomers, and fibrils (but no monomers) all populated in these cells at a time when the first indication of toxicity (nuclear DNA damage) was observed. These experiments provided a strong hint that monomeric forms of htt-ex1 are not involved in toxicity, but we were otherwise unable to implicate a specific toxic self-assembled state because of the overlapping kinetics of formation. To gain a more intimate focus and control over the timelines of htt-ex1 self-assembly and the resulting toxic response, we engineered various htt-ex1-βHP molecules-with and without added β-breaker mutations-that could be expressed in rat neuronal and Drosophila models of HD. In both models, novel htt-ex1-βHP analogues exhibiting strong aggregation in spite of their very short polyQ repeat lengths proved to be toxic, dramatically breaking the "repeat length paradigm" and strongly suggesting that the toxic species must be some kind of aggregate. In both models, β-breaker analogues of htt-ex1-βHP that are slow to make amyloid-instead favoring accumulation of non-β oligomers-were nontoxic. In contrast, htt-ex1-βHP analogues that rapidly progress to amyloid states were toxic, suggesting that an aggregate possessing the fundamental amyloid folding motif is very likely the major toxic species in HD.
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Affiliation(s)
- Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Biomedical Sciences Tower 3, 3501 Fifth Avenue, Pittsburgh, Pennsylvania 15260, United States
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16
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Boatz JC, Piretra T, Lasorsa A, Matlahov I, Conway JF, van der Wel PCA. Protofilament Structure and Supramolecular Polymorphism of Aggregated Mutant Huntingtin Exon 1. J Mol Biol 2020; 432:4722-4744. [PMID: 32598938 DOI: 10.1016/j.jmb.2020.06.021] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 06/01/2020] [Accepted: 06/18/2020] [Indexed: 12/11/2022]
Abstract
Huntington's disease is a progressive neurodegenerative disease caused by expansion of the polyglutamine domain in the first exon of huntingtin (HttEx1). The extent of expansion correlates with disease progression and formation of amyloid-like protein deposits within the brain. The latter display polymorphism at the microscopic level, both in cerebral tissue and in vitro. Such polymorphism can dramatically influence cytotoxicity, leading to much interest in the conditions and mechanisms that dictate the formation of polymorphs. We examine conditions that govern HttEx1 polymorphism in vitro, including concentration and the role of the non-polyglutamine flanking domains. Using electron microscopy, we observe polymorphs that differ in width and tendency for higher-order bundling. Strikingly, aggregation yields different polymorphs at low and high concentrations. Narrow filaments dominate at low concentrations that may be more relevant in vivo. We dissect the role of N- and C-terminal flanking domains using protein with the former (httNT or N17) largely removed. The truncated protein is generated by trypsin cleavage of soluble HttEx1 fusion protein, which we analyze in some detail. Dye binding and solid-state NMR studies reveal changes in fibril surface characteristics and flanking domain mobility. Higher-order interactions appear facilitated by the C-terminal tail, while the polyglutamine forms an amyloid core resembling those of other polyglutamine deposits. Fibril-surface-mediated branching, previously attributed to secondary nucleation, is reduced in absence of httNT. A new model for the architecture of the HttEx1 filaments is presented and discussed in context of the assembly mechanism and biological activity.
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Affiliation(s)
- Jennifer C Boatz
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Talia Piretra
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Alessia Lasorsa
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
| | - Irina Matlahov
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
| | - James F Conway
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA.
| | - Patrick C A van der Wel
- Department of Structural Biology, School of Medicine, University of Pittsburgh, 3501 5th Ave, Biomedical Science Tower 3, Pittsburgh, PA 15213, USA; Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, the Netherlands.
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17
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Gaddi GM, Gisonno RA, Rosú SA, Curto LM, Prieto ED, Schinella GR, Finarelli GS, Cortez MF, Bauzá L, Elías EE, Ramella NA, Tricerri MA. Structural analysis of a natural apolipoprotein A-I variant (L60R) associated with amyloidosis. Arch Biochem Biophys 2020; 685:108347. [DOI: 10.1016/j.abb.2020.108347] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Revised: 03/12/2020] [Accepted: 03/14/2020] [Indexed: 01/11/2023]
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18
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Prajapati KP, Singh AP, Dubey K, Ansari M, Temgire M, Anand BG, Kar K. Myricetin inhibits amyloid fibril formation of globular proteins by stabilizing the native structures. Colloids Surf B Biointerfaces 2020; 186:110640. [DOI: 10.1016/j.colsurfb.2019.110640] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 09/19/2019] [Accepted: 11/10/2019] [Indexed: 02/06/2023]
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19
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Ziaunys M, Sneideris T, Smirnovas V. Exploring the potential of deep-blue autofluorescence for monitoring amyloid fibril formation and dissociation. PeerJ 2019; 7:e7554. [PMID: 31440437 PMCID: PMC6699583 DOI: 10.7717/peerj.7554] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Accepted: 07/25/2019] [Indexed: 02/03/2023] Open
Abstract
Protein aggregation into amyloid fibrils has been linked to multiple neurodegenerative disorders. Determining the kinetics of fibril formation, as well as their structural stability are important for the mechanistic understanding of amyloid aggregation. Tracking both fibril association and dissociation is usually performed by measuring light scattering of the solution or fluorescence of amyloid specific dyes, such as thioflavin-T. A possible addition to these methods is the recently discovered deep-blue autofluorescence (dbAF), which is linked to amyloid formation. In this work we explore the potential of this phenomenon to monitor amyloid fibril formation and dissociation, as well as show its possible relation to fibril size rather than amyloid structure.
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Affiliation(s)
- Mantas Ziaunys
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
| | - Tomas Sneideris
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
| | - Vytautas Smirnovas
- Vilnius University, Life Sciences Center, Institute of Biotechnology, Vilnius, Lithuania
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20
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Anand BG, Prajapati KP, Dubey K, Ahamad N, Shekhawat DS, Rath PC, Joseph GK, Kar K. Self-Assembly of Artificial Sweetener Aspartame Yields Amyloid-like Cytotoxic Nanostructures. ACS NANO 2019; 13:6033-6049. [PMID: 31021591 DOI: 10.1021/acsnano.9b02284] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Recent reports have revealed the intrinsic propensity of single aromatic metabolites to undergo self-assembly and form nanostructures of amyloid nature. Hence, identifying whether aspartame, a universally consumed artificial sweetener, is inherently aggregation prone becomes an important area of investigation. Although the reports on aspartame-linked side effects describe a multitude of metabolic disorders, the mechanistic understanding of such destructive effects is largely mysterious. Since aromaticity, an aggregation-promoting factor, is intrinsic to aspartame's chemistry, it is important to know whether aspartame can undergo self-association and if such a property can predispose any cytotoxicity to biological systems. Our study finds that aspartame molecules, under mimicked physiological conditions, undergo a spontaneous self-assembly process yielding regular β-sheet-like cytotoxic nanofibrils of amyloid nature. The resultant aspartame fibrils were found to trigger amyloid cross-seeding and become a toxic aggregation trap for globular proteins, Aβ peptides, and aromatic metabolites that convert native structures to β-sheet-like fibrils. Aspartame fibrils were also found to induce hemolysis, causing DNA damage resulting in both apoptosis and necrosis-mediated cell death. Specific spatial arrangement between aspartame molecules is predicted to form a regular amyloid-like architecture with a sticky exterior that is capable of promoting viable H-bonds, electrostatic interactions, and hydrophobic contacts with biomolecules, leading to the onset of protein aggregation and cell death. Results reveal that the aspartame molecule is inherently amyloidogenic, and the self-assembly of aspartame becomes a toxic trap for proteins and cells, exposing the bitter side of such a ubiquitously used artificial sweetener.
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Affiliation(s)
- Bibin Gnanadhason Anand
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | | | - Kriti Dubey
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - Naseem Ahamad
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - Dolat Singh Shekhawat
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | - Pramod Chandra Rath
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
| | - George Kodimattam Joseph
- Department of Bioscience and Bioengineering , Indian Institute of Technology Jodhpur , Jodhpur 342037 , India
| | - Karunakar Kar
- School of Life Sciences , Jawaharlal Nehru University , New Delhi 110067 , India
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21
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Skamris T, Marasini C, Madsen KL, Foderà V, Vestergaard B. Early Stage Alpha-Synuclein Amyloid Fibrils are Reservoirs of Membrane-Binding Species. Sci Rep 2019; 9:1733. [PMID: 30741994 PMCID: PMC6370759 DOI: 10.1038/s41598-018-38271-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 12/19/2018] [Indexed: 11/16/2022] Open
Abstract
The presence of αSN fibrils indisputably associates with the development of synucleinopathies. However, while certain fibril morphologies have been linked to downstream pathological phenotypes, others appear less harmful, leading to the concept of fibril strains, originally described in relation to prion disease. Indeed, the presence of fibrils does not associate directly with neurotoxicity. Rather, it has been suggested that the toxic compounds are soluble amyloidogenic oligomers, potentially co-existing with fibrils. Here, combining synchrotron radiation circular dichroism, transmission electron microscopy and binding assays on native plasma membrane sheets, we reveal distinct biological and biophysical differences between initial and matured fibrils, transformed within the timespan of few days. Immature fibrils are reservoirs of membrane-binding species, which in response to even gentle experimental changes release into solution in a reversible manner. In contrast, mature fibrils, albeit macroscopically indistinguishable from their less mature counterparts, are structurally robust, shielding the solution from the membrane active soluble species. We thus show that particular biological activity resides transiently with the fibrillating sample, distinct for one, but not the other, spontaneously formed fibril polymorph. These results shed new light on the principles of fibril polymorphism with consequent impact on future design of assays and therapeutic development.
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Affiliation(s)
- Thomas Skamris
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Carlotta Marasini
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark
| | - Kenneth L Madsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, The Panum Institute, Maersk Tower 7.5, 2200, Copenhagen, Denmark
| | - Vito Foderà
- Department of Pharmacy, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
| | - Bente Vestergaard
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen, Denmark.
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22
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Drombosky KW, Rode S, Kodali R, Jacob TC, Palladino MJ, Wetzel R. Mutational analysis implicates the amyloid fibril as the toxic entity in Huntington's disease. Neurobiol Dis 2018; 120:126-138. [PMID: 30171891 DOI: 10.1016/j.nbd.2018.08.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 08/22/2018] [Accepted: 08/28/2018] [Indexed: 10/28/2022] Open
Abstract
In Huntington disease (HD), an expanded polyglutamine (polyQ > 37) sequence within huntingtin (htt) exon1 leads to enhanced disease risk. It has proved difficult, however, to determine whether the toxic form generated by polyQ expansion is a misfolded or avid-binding monomer, an α-helix-rich oligomer, or a β-sheet-rich amyloid fibril. Here we describe an engineered htt exon1 analog featuring a short polyQ sequence that nonetheless quickly forms amyloid fibrils and causes HD-like toxicity in rat neurons and Drosophila. Additional modifications within the polyQ segment produce htt exon1 analogs that populate only spherical oligomers and are non-toxic in cells and flies. Furthermore, in mixture with expanded-polyQ htt exon1, the latter analogs in vitro suppress amyloid formation and promote oligomer formation, and in vivo rescue neurons and flies expressing mhtt exon1 from dysfunction and death. Thus, in our experiments, while htt exon1 toxicity tracks with aggregation propensity, it does so in spite of the toxic construct's possessing polyQ tracts well below those normally considered to be disease-associated. That is, aggregation propensity proves to be a more accurate surrogate for toxicity than is polyQ repeat length itself, strongly supporting a major toxic role for htt exon1 aggregation in HD. In addition, the results suggest that the aggregates that are most toxic in these model systems are amyloid-related. These engineered analogs are novel tools for mapping properties of polyQ self-assembly intermediates and products that should similarly be useful in the analysis of other expanded polyQ diseases. Small molecules with similar amyloid inhibitory properties might be developed into effective therapeutic agents.
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Affiliation(s)
- Kenneth W Drombosky
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Graduate Program in Molecular Pharmacology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Sascha Rode
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ravi Kodali
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Tija C Jacob
- Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Michael J Palladino
- Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ronald Wetzel
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA 15260, USA; Pittsburgh Institute for Neurodegenerative Diseases (PIND), University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
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