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Teixeira AC, Saraiva MJ. Selective recognition of human small transthyretin aggregates by a novel monoclonal antibody. Amyloid 2023; 30:74-80. [PMID: 36111397 DOI: 10.1080/13506129.2022.2122034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
Abstract
Biochemical characterisation of transthyretin variant TTR Y78F showed that this variant adopts a tetrameric conformation as normal TTR but exhibits some of the characteristics of an intermediate structure in the fibrillogenesis pathway. It was hypothesised that native Y78F might represent an early event in TTR amyloidogenesis. We immunised TTR knock out mice with recombinant variant TTR Y78F. One stable hybridoma named CE11, of the IgM isotype, was tested for reactivity towards several soluble recombinant TTR variants both amyloidogenic and non-amyloidogenic. CE11 only recognises the highly amyloidogenic TTR variants L55P, S52P, A97S, Y78F or acidified TTR wt preparations. At the same time, this clone was negative for TTR V30M, soluble wild type protein or TTR T119M. The reactivity increased with oligomer formation and decreased as mature fibrils grow. After size exclusion chromatography (SEC) followed by sandwich ELISA and native immunoblotting, the mAb recognised two peaks (i) peak 1 present in acidified and in soluble variant proteins preparations with material above 146 KDa (ii) peak 2 only present in soluble L55P and S52P TTR preparations with material between 66 and 146 KDa. mAb CE11 may be a potential tool to survey therapeutical agents against TTR aggregation.
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Affiliation(s)
- A C Teixeira
- Molecular Neurobiology Department, Instituto de Investigação e Inovação em Saúde, i3S, Instituto de Biologia Molecular e Celular, IBMC, Porto, Portugal
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2
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Gomes JR, Lobo A, Nogueira R, Terceiro AF, Costelha S, Lopes IM, Magalhães A, Summavielle T, Saraiva MJ. Neuronal megalin mediates synaptic plasticity-a novel mechanism underlying intellectual disabilities in megalin gene pathologies. Brain Commun 2020; 2:fcaa135. [PMID: 33225275 PMCID: PMC7667529 DOI: 10.1093/braincomms/fcaa135] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 07/14/2020] [Accepted: 07/16/2020] [Indexed: 12/15/2022] Open
Abstract
Donnai-Barrow syndrome, a genetic disorder associated to LRP2 (low-density lipoprotein receptor 2/megalin) mutations, is characterized by unexplained neurological symptoms and intellectual deficits. Megalin is a multifunctional endocytic clearance cell-surface receptor, mostly described in epithelial cells. This receptor is also expressed in the CNS, mainly in neurons, being involved in neurite outgrowth and neuroprotective mechanisms. Yet, the mechanisms involved in the regulation of megalin in the CNS are poorly understood. Using transthyretin knockout mice, a megalin ligand, we found that transthyretin positively regulates neuronal megalin levels in different CNS areas, particularly in the hippocampus. Transthyretin is even able to rescue megalin downregulation in transthyretin knockout hippocampal neuronal cultures, in a positive feedback mechanism via megalin. Importantly, transthyretin activates a regulated intracellular proteolysis mechanism of neuronal megalin, producing an intracellular domain, which is translocated to the nucleus, unveiling megalin C-terminal as a potential transcription factor, able to regulate gene expression. We unveil that neuronal megalin reduction affects physiological neuronal activity, leading to decreased neurite number, length and branching, and increasing neuronal susceptibility to a toxic insult. Finally, we unravel a new unexpected role of megalin in synaptic plasticity, by promoting the formation and maturation of dendritic spines, and contributing for the establishment of active synapses, both in in vitro and in vivo hippocampal neurons. Moreover, these structural and synaptic roles of megalin impact on learning and memory mechanisms, since megalin heterozygous mice show hippocampal-related memory and learning deficits in several behaviour tests. Altogether, we unveil a complete novel role of megalin in the physiological neuronal activity, mainly in synaptic plasticity with impact in learning and memory. Importantly, we contribute to disclose the molecular mechanisms underlying the cognitive and intellectual disabilities related to megalin gene pathologies.
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Affiliation(s)
- João R Gomes
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Andrea Lobo
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Renata Nogueira
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Ana F Terceiro
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Susete Costelha
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
| | - Igor M Lopes
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Ana Magalhães
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Teresa Summavielle
- I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal.,Addiction Biology Group, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal
| | - Maria J Saraiva
- Molecular Neurobiology Unit, IBMC- Instituto de Biologia Molecular e Celular, 4200-135 Porto, Portugal.,I3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal
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3
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Ré A, Campos I, Saraiva MJ, Puga J, Keizer JJ, Gonçalves FJM, Pereira JL, Abrantes N. Wildfire effects on two freshwater producers: Combining in-situ and laboratory bioassays. Ecotoxicol Environ Saf 2020; 194:110361. [PMID: 32126411 DOI: 10.1016/j.ecoenv.2020.110361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Revised: 02/18/2020] [Accepted: 02/19/2020] [Indexed: 06/10/2023]
Abstract
Mediterranean forests are highly susceptible to wildfires, which can cause several impacts not only within burnt areas but also on downstream aquatic ecosystems. The ashes' washout from burnt areas by surface runoff can be a diffuse source of toxic substances, such as metals, when reaching the nearby aquatic systems, and can be noxious to aquatic organisms. The present work aimed at assessing the ecotoxicological effects of post-fire contamination on two aquatic producers (the microalgae Raphidocelis subcapitata and the macrophyte Lemna minor) through in-situ bioassays, validating the obtained results with the outcomes of laboratory bioassays with surface water collected simultaneously. Four distinct sites were selected in a basin partially burnt (Ceira river basin; Coimbra district, Portugal) for bioassay deployment: one site upstream the burnt area in the Ceira river (RUS); three sites located under the influence of the burnt area, one immediately downstream of the burnt area in the Ceira river (RDS) and the other two in tributary streams within the burnt area (BS1 and BS2). The in-situ bioassays lasted for 13 days and began following the first post-fire major rain events. Results showed that the microalgae growth rate was able to distinguish the three sites within and downstream of the burnt area (BS1, BS2, RDS) from the site upstream (RUS). By contrast, the macrophytes growth rate only allowed to differentiate between the sites within the burnt area (BS1 and BS2) and those up- and downstream of the burnt area (RUS and RDS). The in-situ results for both species were corroborated with the results of the laboratory experiments, supporting the use of laboratory surrogates for a screening assessment of wildfire impacts in aquatic ecosystems. Direct causal relationships between the observed ecotoxicological effects on R. subcapitata and L. minor and the physical-chemical parameters of the water samples were difficult to establish, although the results suggest (i) a role of differential major and trace metal load in explaining species growth variation; (ii) interaction between metals and/or between metals and other field parameters are likely to modulate the biological responses to the challenges deriving from wildfire runoff.
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Affiliation(s)
- Ana Ré
- Department of Biology and CESAM (Centre for Environmental and Marine Studies), University of Aveiro, Aveiro, Portugal
| | - Isabel Campos
- Earth Surface Processes Team, CESAM and Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - Maria J Saraiva
- Earth Surface Processes Team, CESAM and Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - João Puga
- Earth Surface Processes Team, CESAM and Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - Jan Jacob Keizer
- Earth Surface Processes Team, CESAM and Department of Environment and Planning, University of Aveiro, Aveiro, Portugal
| | - Fernando J M Gonçalves
- Department of Biology and CESAM (Centre for Environmental and Marine Studies), University of Aveiro, Aveiro, Portugal
| | - Joana L Pereira
- Department of Biology and CESAM (Centre for Environmental and Marine Studies), University of Aveiro, Aveiro, Portugal
| | - Nelson Abrantes
- Earth Surface Processes Team, CESAM and Department of Environment and Planning, University of Aveiro, Aveiro, Portugal.
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Gomes JR, Sárkány Z, Teixeira A, Nogueira R, Cabrito I, Soares H, Wittelsberger A, Stortelers C, Macedo-Ribeiro S, Vanlandschoot P, Saraiva MJ. Anti-TTR Nanobodies Allow the Identification of TTR Neuritogenic Epitope Associated with TTR-Megalin Neurotrophic Activities. ACS Chem Neurosci 2019; 10:704-715. [PMID: 30346709 DOI: 10.1021/acschemneuro.8b00502] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Transthyretin (TTR) has intrinsic neurotrophic physiological activities independent from its thyroxine ligands, which involve activation of signaling pathways through interaction with megalin. Still, the megalin binding motif on TTR is unknown. Nanobodies (Nb) have the ability to bind "hard to reach" epitopes being useful tools for protein/structure function. In this work, we characterize two anti-TTR Nanobodies, with similar mouse TTR binding affinities, although only one is able to block its neuritogenic activity (169F7_Nb). Through epitope mapping, we identified amino acids 14-18, at the entrance of the TTR central channel, to be important for interaction with megalin, and a stable TTR K15N mutant in that region was constructed. The TTR K15N mutant lacks neuritogenic activity, indicating that K15 is critical for TTR neuritogenic activity. Thus, we identify the putative binding site for megalin and describe two Nanobodies that will allow research and clarification of TTR physiological properties, regarding its neurotrophic effects.
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Affiliation(s)
- João R. Gomes
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Zsuzsa Sárkány
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Biomolecular Structure & Function, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Anabela Teixeira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | - Renata Nogueira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | | | | | | | | | - Sandra Macedo-Ribeiro
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Biomolecular Structure & Function, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
| | | | - Maria J. Saraiva
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto 4200-135, Portugal
- Molecular Neurobiology, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto 4200-135, Portugal
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5
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Simões CJV, Almeida ZL, Cardoso AL, Bezerra F, Almeida MR, Beirão J, Pinho E Melo TMVD, Saraiva MJ, Brito RMM. Lead optimization of resilient next-generation transthyretin stabilizers for multiple target-product profiles: approaching the CNS. Amyloid 2019; 26:77-78. [PMID: 31343302 DOI: 10.1080/13506129.2019.1583195] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Carlos J V Simões
- a Instituto Pedro Nunes, BSIM Therapeutics , Coimbra , Portugal.,b Coimbra Chemistry Centre and Chemistry Department, University of Coimbra , Coimbra , Portugal
| | - Zaida L Almeida
- b Coimbra Chemistry Centre and Chemistry Department, University of Coimbra , Coimbra , Portugal
| | - Ana L Cardoso
- b Coimbra Chemistry Centre and Chemistry Department, University of Coimbra , Coimbra , Portugal
| | - Filipa Bezerra
- c i3S-IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto , Porto , Portugal
| | - Maria R Almeida
- c i3S-IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto , Porto , Portugal.,d ICBAS - Institute of Biomedical Sciences Abel Salazar University of Porto , Porto , Portugal
| | - João Beirão
- e Centro Hospitalar do Porto, Ophtalmology Service , Porto , Portugal
| | | | - Maria J Saraiva
- c i3S-IBMC - Instituto de Biologia Molecular e Celular Universidade do Porto , Porto , Portugal
| | - Rui M M Brito
- b Coimbra Chemistry Centre and Chemistry Department, University of Coimbra , Coimbra , Portugal.,f Instituto Pedro Nunes, BSIM Therapeutics , Coimbra , Portugal
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6
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Gomes JR, Cabrito I, Soares HR, Costelha S, Teixeira A, Wittelsberger A, Stortelers C, Vanlandschoot P, Saraiva MJ. Delivery of an anti-transthyretin Nanobody to the brain through intranasal administration reveals transthyretin expression and secretion by motor neurons. J Neurochem 2018. [PMID: 29527688 PMCID: PMC6001800 DOI: 10.1111/jnc.14332] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Transthyretin (TTR) is a transport protein of retinol and thyroxine in serum and CSF, which is mainly secreted by liver and choroid plexus, and in smaller amounts in other cells throughout the body. The exact role of TTR and its specific expression in Central Nervous System (CNS) remains understudied. We investigated TTR expression and metabolism in CNS, through the intranasal and intracerebroventricular delivery of a specific anti-TTR Nanobody to the brain, unveiling Nanobody pharmacokinetics to the CNS. In TTR deficient mice, we observed that anti-TTR Nanobody was successfully distributed throughout all brain areas, and also reaching the spinal cord. In wild-type mice, a similar distribution pattern was observed. However, in areas known to be rich in TTR, reduced levels of Nanobody were found, suggesting potential target-mediated effects. Indeed, in wild-type mice, the anti-TTR Nanobody was specifically internalized in a receptor-mediated process, by neuronal-like cells, which were identified as motor neurons. Whereas in KO TTR mice Nanobody was internalized by all cells, for late lysosomal degradation. Moreover, we demonstrate that in vivo motor neurons also actively synthesize TTR. Finally, in vitro cultured primary motor neurons were also found to synthesize and secrete TTR into culture media. Thus, through a novel intranasal CNS distribution study with an anti-TTR Nanobody, we disclose a new cell type capable of synthesizing TTR, which might be important for the understanding of the physiological role of TTR, as well as in pathological conditions where TTR levels are altered in CSF, such as amyotrophic lateral sclerosis.
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Affiliation(s)
- João R Gomes
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | | | | | - Susete Costelha
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | - Anabela Teixeira
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
| | | | | | | | - Maria J Saraiva
- Instituto de Investigação e Inovação em Saúde (I3S), University of Porto, Porto, Portugal.,Neurobiology Unit, IBMC- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
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7
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Affiliation(s)
- Paula Gonçalves
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Porto , Portugal and.,b Department of Neurobiologia Molecular , IBMC, Universidade do Porto , Porto , Portugal
| | - Helena Martins
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Porto , Portugal and.,b Department of Neurobiologia Molecular , IBMC, Universidade do Porto , Porto , Portugal
| | - Susete Costelha
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Porto , Portugal and.,b Department of Neurobiologia Molecular , IBMC, Universidade do Porto , Porto , Portugal
| | - Maria J Saraiva
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Porto , Portugal and.,b Department of Neurobiologia Molecular , IBMC, Universidade do Porto , Porto , Portugal
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8
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Gonçalves NP, Martins D, Saraiva MJ. The importance of pre-clinical studies in animal models of TTR amyloidosis for the discovery of novel patient disease biomarkers. Amyloid 2017; 24:83-84. [PMID: 28434291 DOI: 10.1080/13506129.2016.1278362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Affiliation(s)
- N P Gonçalves
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Portugal and.,b IBMC Unidade de Neurobiologia Molecular, Universidade do Porto , Portugal
| | - D Martins
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Portugal and.,b IBMC Unidade de Neurobiologia Molecular, Universidade do Porto , Portugal
| | - M J Saraiva
- a Instituto de Inovação e Investigação em Saúde (I3S), Universidade do Porto , Portugal and.,b IBMC Unidade de Neurobiologia Molecular, Universidade do Porto , Portugal
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9
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Lopes CDF, Gonçalves NP, Gomes CP, Saraiva MJ, Pêgo AP. BDNF gene delivery mediated by neuron-targeted nanoparticles is neuroprotective in peripheral nerve injury. Biomaterials 2016; 121:83-96. [PMID: 28081461 DOI: 10.1016/j.biomaterials.2016.12.025] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Revised: 12/05/2016] [Accepted: 12/21/2016] [Indexed: 12/22/2022]
Abstract
Neuron-targeted gene delivery is a promising strategy to treat peripheral neuropathies. Here we propose the use of polymeric nanoparticles based on thiolated trimethyl chitosan (TMCSH) to mediate targeted gene delivery to peripheral neurons upon a peripheral and minimally invasive intramuscular administration. Nanoparticles were grafted with the non-toxic carboxylic fragment of the tetanus neurotoxin (HC) to allow neuron targeting and were explored to deliver a plasmid DNA encoding for the brain-derived neurotrophic factor (BDNF) in a peripheral nerve injury model. The TMCSH-HC/BDNF nanoparticle treatment promoted the release and significant expression of BDNF in neural tissues, which resulted in an enhanced functional recovery after injury as compared to control treatments (vehicle and non-targeted nanoparticles), associated with an improvement in key pro-regenerative events, namely, the increased expression of neurofilament and growth-associated protein GAP-43 in the injured nerves. Moreover, the targeted nanoparticle treatment was correlated with a significantly higher density of myelinated axons in the distal stump of injured nerves, as well as with preservation of unmyelinated axon density as compared with controls and a protective role in injury-denervated muscles, preventing them from denervation. These results highlight the potential of TMCSH-HC nanoparticles as non-viral gene carriers to deliver therapeutic genes into the peripheral neurons and thus, pave the way for their use as an effective therapeutic intervention for peripheral neuropathies.
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Affiliation(s)
- Cátia D F Lopes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; FMUP - Faculdade de Medicina da Universidade do Porto, Alameda Prof. Hernâni Monteiro, 4200-319 Porto, Portugal
| | - Nádia P Gonçalves
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Carla P Gomes
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; FEUP - Faculdade de Engenharia, Universidade do Porto, Porto, R. Dr. Roberto Frias s/n, 4200-465 Porto, Portugal
| | - Maria J Saraiva
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal
| | - Ana P Pêgo
- i3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; INEB - Instituto de Engenharia Biomédica, Universidade do Porto, Rua Alfredo Allen, 208, 4200-135 Porto, Portugal; FEUP - Faculdade de Engenharia, Universidade do Porto, Porto, R. Dr. Roberto Frias s/n, 4200-465 Porto, Portugal; ICBAS - Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, R. Jorge de Viterbo Ferreira 228, Porto, Portugal.
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10
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Pires RH, Saraiva MJ, Damas AM, Kellermayer MSZ. Force spectroscopy reveals the presence of structurally modified dimers in transthyretin amyloid annular oligomers. J Mol Recognit 2016; 30. [PMID: 27808434 DOI: 10.1002/jmr.2587] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Revised: 09/21/2016] [Accepted: 09/30/2016] [Indexed: 12/17/2022]
Abstract
Toxicity in amyloidogenic protein misfolding disorders is thought to involve intermediate states of aggregation associated with the formation of amyloid fibrils. Despite their relevance, the heterogeneity and transience of these oligomers have placed great barriers in our understanding of their structural properties. Among amyloid intermediates, annular oligomers or annular protofibrils have raised considerable interest because they may contribute to a mechanism of cellular toxicity via membrane permeation. Here we investigated, by using AFM force spectroscopy, the structural detail of amyloid annular oligomers from transthyretin (TTR), a protein involved in systemic and neurodegenerative amyloidogenic disorders. Manipulation was performed in situ, in the absence of molecular handles and using persistence length-fit values to select relevant curves. Force curves reveal the presence of dimers in TTR annular oligomers that unfold via a series of structural intermediates. This is in contrast with the manipulation of native TTR that was more often manipulated over length scales compatible with a TTR monomer and without unfolding intermediates. Imaging and force spectroscopy data suggest that dimers are formed by the assembly of monomers in a head-to-head orientation with a nonnative interface along their β-strands. Furthermore, these dimers stack through nonnative contacts that may enhance the stability of the misfolded structure.
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Affiliation(s)
- Ricardo H Pires
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.,Institute for Molecular and Cell Biology (IBMC), Porto, Portugal
| | - Maria J Saraiva
- Institute for Molecular and Cell Biology (IBMC), Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Ana M Damas
- Institute for Molecular and Cell Biology (IBMC), Porto, Portugal.,Instituto de Ciências Biomédicas de Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Miklós S Z Kellermayer
- Department of Biophysics and Radiation Biology, Semmelweis University, Budapest, Hungary.,MTA-SE Molecular Biophysics Research Group, Budapest, Hungary
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11
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Butler JS, Chan A, Costelha S, Fishman S, Willoughby JLS, Borland TD, Milstein S, Foster DJ, Gonçalves P, Chen Q, Qin J, Bettencourt BR, Sah DW, Alvarez R, Rajeev KG, Manoharan M, Fitzgerald K, Meyers RE, Nochur SV, Saraiva MJ, Zimmermann TS. Preclinical evaluation of RNAi as a treatment for transthyretin-mediated amyloidosis. Amyloid 2016; 23:109-18. [PMID: 27033334 PMCID: PMC4898164 DOI: 10.3109/13506129.2016.1160882] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
ATTR amyloidosis is a systemic, debilitating and fatal disease caused by transthyretin (TTR) amyloid accumulation. RNA interference (RNAi) is a clinically validated technology that may be a promising approach to the treatment of ATTR amyloidosis. The vast majority of TTR, the soluble precursor of TTR amyloid, is expressed and synthesized in the liver. RNAi technology enables robust hepatic gene silencing, the goal of which would be to reduce systemic levels of TTR and mitigate many of the clinical manifestations of ATTR that arise from hepatic TTR expression. To test this hypothesis, TTR-targeting siRNAs were evaluated in a murine model of hereditary ATTR amyloidosis. RNAi-mediated silencing of hepatic TTR expression inhibited TTR deposition and facilitated regression of existing TTR deposits in pathologically relevant tissues. Further, the extent of deposit regression correlated with the level of RNAi-mediated knockdown. In comparison to the TTR stabilizer, tafamidis, RNAi-mediated TTR knockdown led to greater regression of TTR deposits across a broader range of affected tissues. Together, the data presented herein support the therapeutic hypothesis behind TTR lowering and highlight the potential of RNAi in the treatment of patients afflicted with ATTR amyloidosis.
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Affiliation(s)
| | - Amy Chan
- a Alnylam Pharmaceuticals , Cambridge , MA , USA
| | - Susete Costelha
- b Instituto de Investigação e Inovação em Saúde, Universidade do Porto , Porto , Portugal .,c Molecular Neurobiology, IBMC - Institute for Molecular and Cell Biology Porto , Porto , Portugal
| | | | | | | | | | | | - Paula Gonçalves
- b Instituto de Investigação e Inovação em Saúde, Universidade do Porto , Porto , Portugal .,c Molecular Neurobiology, IBMC - Institute for Molecular and Cell Biology Porto , Porto , Portugal
| | - Qingmin Chen
- a Alnylam Pharmaceuticals , Cambridge , MA , USA
| | - June Qin
- a Alnylam Pharmaceuticals , Cambridge , MA , USA
| | | | - Dinah W Sah
- a Alnylam Pharmaceuticals , Cambridge , MA , USA
| | - Rene Alvarez
- a Alnylam Pharmaceuticals , Cambridge , MA , USA
| | | | | | | | | | | | - Maria J Saraiva
- b Instituto de Investigação e Inovação em Saúde, Universidade do Porto , Porto , Portugal .,c Molecular Neurobiology, IBMC - Institute for Molecular and Cell Biology Porto , Porto , Portugal
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12
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Ferreira N, Gonçalves NP, Saraiva MJ, Almeida MR. Curcumin: A multi-target disease-modifying agent for late-stage transthyretin amyloidosis. Sci Rep 2016; 6:26623. [PMID: 27197872 PMCID: PMC4873750 DOI: 10.1038/srep26623] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 05/04/2016] [Indexed: 12/21/2022] Open
Abstract
Transthyretin amyloidoses encompass a variety of acquired and hereditary diseases triggered by systemic extracellular accumulation of toxic transthyretin aggregates and fibrils, particularly in the peripheral nervous system. Since transthyretin amyloidoses are typically complex progressive disorders, therapeutic approaches aiming multiple molecular targets simultaneously, might improve therapy efficacy and treatment outcome. In this study, we evaluate the protective effect of physiologically achievable doses of curcumin on the cytotoxicity induced by transthyretin oligomers in vitro by showing reduction of caspase-3 activity and the levels of endoplasmic reticulum-resident chaperone binding immunoglobulin protein. When given to an aged Familial Amyloidotic Polyneuropathy mouse model, curcumin not only reduced transthyretin aggregates deposition and toxicity in both gastrointestinal tract and dorsal root ganglia but also remodeled congophilic amyloid material in tissues. In addition, curcumin enhanced internalization, intracellular transport and degradation of transthyretin oligomers by primary macrophages from aged Familial Amyloidotic Polyneuropathy transgenic mice, suggesting an impaired activation of naïve phagocytic cells exposed to transthyretin toxic intermediate species. Overall, our results clearly support curcumin or optimized derivatives as promising multi-target disease-modifying agent for late-stage transthyretin amyloidosis.
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Affiliation(s)
- Nelson Ferreira
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal
| | - Nádia P Gonçalves
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua Jorge Viterbo Ferreira 228, 4050 - 313 Porto, Portugal
| | - Maria J Saraiva
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua Jorge Viterbo Ferreira 228, 4050 - 313 Porto, Portugal
| | - Maria R Almeida
- IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,i3S - Instituto de Investigação e Inovação em Saúde da Universidade do Porto, Rua Alfredo Allen, 208, 4200 - 135 Porto, Portugal.,ICBAS, Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Rua Jorge Viterbo Ferreira 228, 4050 - 313 Porto, Portugal
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13
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Simões CJV, Almeida ZL, Costa D, Jesus CSH, Cardoso AL, Almeida MR, Saraiva MJ, Pinho E Melo TMVD, Brito RMM. A novel bis-furan scaffold for transthyretin stabilization and amyloid inhibition. Eur J Med Chem 2016; 121:823-840. [PMID: 27020050 DOI: 10.1016/j.ejmech.2016.02.074] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Revised: 02/26/2016] [Accepted: 02/29/2016] [Indexed: 12/22/2022]
Abstract
The design and synthesis of a novel bis-furan scaffold tailored for high efficiency at inhibiting transthyretin amyloid formation is reported. In vitro results show that the discovered compounds are more efficient inhibitors of amyloid formation than tafamidis, a drug currently used in the treatment of familial amyloid polyneuropathy (FAP), despite their lower molecular weight and lipophilicity. Moreover, ex vivo experiments with the strongest inhibitor in the series, conducted in human blood plasma from normal and FAP Val30Met-transthyretin carriers, disclose remarkable affinity and selectivity profiles. The promises and challenges facing further development of this compound are discussed under the light of increasing evidence implicating transthyretin stability as a key factor not only in transthyretin amyloidoses and several associated co-morbidities, but also in Alzheimer's disease.
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Affiliation(s)
- Carlos J V Simões
- BSIM(2) - Drug Discovery, Parque Tecnológico de Cantanhede, 3060-197 Cantanhede, Portugal; Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal.
| | - Zaida L Almeida
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal; Center for Neuroscience and Cell Biology, Universidade de Coimbra, 3004-504 Coimbra, Portugal
| | - Dora Costa
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Catarina S H Jesus
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal; Center for Neuroscience and Cell Biology, Universidade de Coimbra, 3004-504 Coimbra, Portugal
| | - Ana L Cardoso
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Maria R Almeida
- I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto; ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal
| | - Maria J Saraiva
- I3S - Instituto de Investigação e Inovação em Saúde, Universidade do Porto, 4200-135 Porto, Portugal; IBMC - Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto
| | - Teresa M V D Pinho E Melo
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal
| | - Rui M M Brito
- Centro de Química de Coimbra and Departamento de Química, Universidade de Coimbra, 3004-535 Coimbra, Portugal; Center for Neuroscience and Cell Biology, Universidade de Coimbra, 3004-504 Coimbra, Portugal.
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Batista AR, Gianni D, Ventosa M, Coelho AV, Almeida MR, Sena-Esteves M, Saraiva MJ. Erratum: Gene therapy approach to FAP: in vivo influence of T119M in TTR deposition in a transgenic V30M mouse model. Gene Ther 2014. [DOI: 10.1038/gt.2014.111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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15
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Conejos-Sánchez I, Cardoso I, Oteo-Vives M, Romero-Sanz E, Paul A, Sauri AR, Morcillo MA, Saraiva MJ, Vicent MJ. Polymer-doxycycline conjugates as fibril disrupters: an approach towards the treatment of a rare amyloidotic disease. J Control Release 2014; 198:80-90. [PMID: 25481444 DOI: 10.1016/j.jconrel.2014.12.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 11/01/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
The term amyloidosis describes neurological diseases where an abnormal protein is misfolded and accumulated as deposits in organs and tissues, known as amyloid, disrupting their normal function. In the most common familial amyloid polyneuropathy (FAP), transthyretin (TTR) displays this role primarily affecting the peripheral nervous system (PNS). Advanced stages of this inherited rare amyloidosis, present as fibril deposits that are responsible for disease progression. In order to stop disease progression, herein we designed an efficient family of nanoconjugates as fibril disrupters. These polymer conjugates are based on doxycycline (doxy), already in phase II trials for Alzheimer's disease, covalently linked to poly-l-glutamic acid (PGA). The conjugates were rationally designed, looking at drug loading and drug release rate by adequate linker design, always considering the physiological conditions at the molecular target site. Conjugation of doxycycline exhibited greater potential towards TTR fibril disaggregation in vitro compared to the parent drug. Exhaustive physico-chemical evaluation of these polymer-drug conjugates concluded that drug release was unnecessary for activity, highlighting the importance of an appropriate linker. Furthermore, biodistribution studies through optical imaging (OI) and the use of radiolabelled polymer-drug conjugates demonstrated conjugate safety profile and renal clearance route of the selected PGA-doxy candidate, settling the adequacy of our conjugate for future in vivo evaluation. Furthermore, preliminary studies in an FAP in vivo model at early stages of disease development showed non-organ toxicity evidences. This nanosized-system raises a promising treatment for advanced stages of this rare amyloidotic disease, and also presents a starting point for possible application within other amyloidosis-related diseases, such as Alzheimer's disease.
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Affiliation(s)
- Inmaculada Conejos-Sánchez
- Polymer Therapeutics Lab., Centro de Investigación Príncipe Felipe (CIPF), Av. Eduardo Primo Yúfera 3, Valencia 46012, Spain
| | - Isabel Cardoso
- Instituto de Biología Molecular e Celular (IBMC), Rua do Campo Alegre 823, Porto 4150-180, Portugal
| | - Marta Oteo-Vives
- Biomedical Applications of Radioisotopes and Pharmacokinetics Unit, CIEMAT, Av. Complutense 40, Madrid 28040, Spain
| | - Eduardo Romero-Sanz
- Biomedical Applications of Radioisotopes and Pharmacokinetics Unit, CIEMAT, Av. Complutense 40, Madrid 28040, Spain
| | - Alison Paul
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom
| | - Amparo Ruiz Sauri
- Pathology Department, University of Valencia, Blasco Ibáñez 15, Valencia 46010, Spain
| | - Miguel A Morcillo
- Biomedical Applications of Radioisotopes and Pharmacokinetics Unit, CIEMAT, Av. Complutense 40, Madrid 28040, Spain
| | - Maria J Saraiva
- Instituto de Biología Molecular e Celular (IBMC), Rua do Campo Alegre 823, Porto 4150-180, Portugal
| | - María J Vicent
- Polymer Therapeutics Lab., Centro de Investigación Príncipe Felipe (CIPF), Av. Eduardo Primo Yúfera 3, Valencia 46012, Spain.
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Batista AR, Gianni D, Ventosa M, Coelho AV, Almeida MR, Sena-Esteves M, Saraiva MJ. Gene therapy approach to FAP: in vivo influence of T119M in TTR deposition in a transgenic V30M mouse model. Gene Ther 2014; 21:1041-50. [DOI: 10.1038/gt.2014.86] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 07/16/2014] [Accepted: 08/06/2014] [Indexed: 11/09/2022]
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Saraiva MJ, Salvador ÂC, Fernandes T, Ferreira JP, Barros AS, Rocha SM, Fonseca C. Three mammal species distinction through the analysis of scats chemical composition provided by comprehensive two-dimensional gas chromatography. BIOCHEM SYST ECOL 2014. [DOI: 10.1016/j.bse.2014.02.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Conejos–Sánchez I, Cardoso I, Saraiva MJ, Vicent MJ. Targeting a rare amyloidotic disease through rationally designed polymer conjugates. J Control Release 2014; 178:95-100. [DOI: 10.1016/j.jconrel.2014.01.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Revised: 01/16/2014] [Accepted: 01/21/2014] [Indexed: 01/26/2023]
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Misumi Y, Ando Y, Gonçalves NP, Saraiva MJ. Fibroblasts endocytose and degrade transthyretin aggregates in transthyretin-related amyloidosis. J Transl Med 2013; 93:911-20. [PMID: 23817086 DOI: 10.1038/labinvest.2013.83] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Revised: 05/24/2013] [Accepted: 06/03/2013] [Indexed: 12/12/2022] Open
Abstract
Transthyretin (TTR)-related amyloidosis is a fatal disorder characterized by systemic extracellular deposition of TTR amyloid fibrils. Mutations in the TTR gene cause an autosomal dominant form of the disease-familial amyloidotic polyneuropathy (FAP). Wild-type (WT) TTR can also form amyloid fibrils in elderly patients with senile systemic amyloidosis. Regression of amyloid deposits in FAP patients who undergo liver transplantation to remove the main source of mutant TTR suggests the existence of mechanisms for the clearance of TTR deposits from the extracellular matrix (ECM), but the precise mechanisms are largely unknown. Because fibroblasts are abundant, playing a central role in the maintenance of the ECM and because the skin is one of the major sites of soluble TTR catabolism, in the present study, we analyzed their role in clearance of TTR aggregates. In vitro studies with a fibroblast cell line revealed that fibroblasts endocytosed and degraded aggregated TTR. Subcutaneous injection of soluble and aggregated TTR into WT mice showed internalization and clearance over time by both fibroblasts and macrophages. Immunohistochemical studies of skin biopsies from V30M patients, asymptomatic carriers, recipients of domino FAP livers as well as transgenic mice for human V30M showed intracellular TTR immunoreactivity in fibroblasts and macrophages that increased with clinical status and with age in transgenic mice. Overall, the present in vitro and in vivo data show that fibroblasts endocytose and degrade TTR aggregates. The function or dysfunction of TTR clearance by fibroblasts may have important implications for the development, progression, and regression of TTR deposition in the ECM.
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Affiliation(s)
- Yohei Misumi
- Molecular Neurobiology, IBMC-Instituto de Biologia Molecular e Celular, Porto, Portugal
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Teixeira AC, Saraiva MJ. Presence of N-glycosylated transthyretin in plasma of V30M carriers in familial amyloidotic polyneuropathy: an escape from ERAD. J Cell Mol Med 2013; 17:429-35. [PMID: 23387326 PMCID: PMC3823024 DOI: 10.1111/jcmm.12024] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Accepted: 12/20/2012] [Indexed: 11/27/2022] Open
Abstract
Familial amyloid polyneuropathy (FAP) is an autosomal dominant disease characterized by deposition of amyloid related to the presence of mutations in the transthyretin (TTR) gene. TTR is mainly synthesized in liver, choroid plexuses of brain and pancreas and secreted to plasma and cerebrospinal fluid (CSF). Although it possesses a sequon for N-glycosylation N-D-S at position 98, it is not secreted as a glycoprotein. The most common FAP-associated mutation is TTR V30M. In a screening for monoclonal antibodies developed against an amyloidogenic TTR form, we detected a distinct TTR with slower electrophoretic mobility in Western of plasma from carriers of the V30M mutation, not present in normal plasma. Mass spectrometry analyses of this slower migrating TTR (SMT) identified both wild-type and mutant V30M; SMT was undetectable upon N-glycosidase F treatment. Furthermore, SMT readily disappeared in the plasma of V30M - FAP patients after liver transplantation and appeared in plasma of transplanted domino individuals that received a V30M liver. SMT was also detected in plasma, but not in CSF of transgenic mice for the human V30M mutation. A hepatoma cell line transduced to express human V30M did not present the SMT modification in secretion media. Glycosylated TTR was absent in fibrils extracted from human kidney V30M autopsy tissue or in TTR aggregates extracted from the intestine of human TTR transgenic mice. Studies on the metabolism of this novel, glycosylated TTR secreted from FAP liver are warranted to provide new mechanisms in protein quality control and etiopathogenesis of the disease.
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Affiliation(s)
- Anabela C Teixeira
- Molecular Neurobiology, Instituto de Biologia Molecular e Celular, IBMC, Porto, Portugal
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Saraiva MJ, Magalhaes J, Ferreira N, Almeida MR. Transthyretin deposition in familial amyloidotic polyneuropathy. Curr Med Chem 2012; 19:2304-11. [PMID: 22471982 DOI: 10.2174/092986712800269236] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2011] [Revised: 11/15/2011] [Accepted: 01/09/2012] [Indexed: 11/22/2022]
Abstract
The subject of the review is on hereditary transthyretin (TTR) amyloidosis which is a genetically transmitted disease that results from a mutation in the gene encoding the plasma TTR protein. TTR is a transport protein for thyroid hormones and vitamin A and is predominantly synthesised in the liver. Although originally regarded as a rare disease, it is now becoming clear that many kindreds exist worldwide. Current knowledge and hypotheses on the biology of TTR, mechanisms of TTR amyloid fibril formation, phenotypic consequences TTR amyloid deposition and pre-clinical models of the disease will be discussed.
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Affiliation(s)
- M J Saraiva
- Instituto de Biologia Molecular e Celular, Universidade do Porto, Portugal.
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Pires RH, Karsai Á, Saraiva MJ, Damas AM, Kellermayer MSZ. Distinct annular oligomers captured along the assembly and disassembly pathways of transthyretin amyloid protofibrils. PLoS One 2012; 7:e44992. [PMID: 22984597 PMCID: PMC3440338 DOI: 10.1371/journal.pone.0044992] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Accepted: 08/15/2012] [Indexed: 11/20/2022] Open
Abstract
Background Defects in protein folding may lead to severe degenerative diseases characterized by the appearance of amyloid fibril deposits. Cytotoxicity in amyloidoses has been linked to poration of the cell membrane that may involve interactions with amyloid intermediates of annular shape. Although annular oligomers have been detected in many amyloidogenic systems, their universality, function and molecular mechanisms of appearance are debated. Methodology/Principal Findings We investigated with high-resolution in situ atomic force microscopy the assembly and disassembly of transthyretin (TTR) amyloid protofibrils formed of the native protein by pH shift. Annular oligomers were the first morphologically distinct intermediates observed in the TTR aggregation pathway. Morphological analysis suggests that they can assemble into a double-stack of octameric rings with a 16±2 nm diameter, and displaying the tendency to form linear structures. According to light scattering data coupled to AFM imaging, annular oligomers appeared to undergo a collapse type of structural transition into spheroid oligomers containing 8–16 monomers. Disassembly of TTR amyloid protofibrils also resulted in the rapid appearance of annular oligomers but with a morphology quite distinct from that observed in the assembly pathway. Conclusions/Significance Our observations indicate that annular oligomers are key dynamic intermediates not only in the assembly but also in the disassembly of TTR protofibrils. The balance between annular and more compact forms of aggregation could be relevant for cytotoxicity in amyloidogenic disorders.
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Affiliation(s)
- Ricardo H. Pires
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- * E-mail: (RHP); (AMD); (MSZK)
| | - Árpád Karsai
- Department of Biophysics, University of Pécs, Pécs, Hungary
| | - Maria J. Saraiva
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal
| | - Ana M. Damas
- Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
- Instituto de Ciências Biomédicas de Abel Salazar, University of Porto, Porto, Portugal
- * E-mail: (RHP); (AMD); (MSZK)
| | - Miklós S. Z. Kellermayer
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Budapest, Hungary
- * E-mail: (RHP); (AMD); (MSZK)
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Obici L, Cortese A, Lozza A, Lucchetti J, Gobbi M, Palladini G, Perlini S, Saraiva MJ, Merlini G. Doxycycline plus tauroursodeoxycholic acid for transthyretin amyloidosis: a phase II study. Amyloid 2012; 19 Suppl 1:34-6. [PMID: 22551192 DOI: 10.3109/13506129.2012.678508] [Citation(s) in RCA: 153] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We designed a phase II, open-label study to evaluate the efficacy, tolerability, safety, and pharmacokinetics of orally doxycycline (100 mg BID) and tauroursodeoxycholic acid (TUDCA) (250 mg three times/day) administered continuously for 12 months. Primary endpoint is response rate defined as nonprogression of the neuropathy and of the cardiomyopathy. Since July 2010, we enrolled 20 patients. Seventeen patients have hereditary ATTR, two patients have senile systemic amyloidosis, and one is a domino recipient. Seven patients completed 12-month treatment, 10 completed 6-month treatment, two discontinued because of poor tolerability, and one is lost at follow-up. No serious adverse events were registered. No clinical progression of cardiac involvement was observed. The neuropathy (Neuropathy Impairment Score in the Lower Limbs [NIS-LL] and Kumamoto score) remained substantially stable over 1 year. These preliminary data indicate that the combination of Doxy-TUDCA stabilizes the disease for at least 1 year in the majority of patients with an acceptable toxicity profile.
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Affiliation(s)
- Laura Obici
- Amyloid Research and Treatment Center, Fondazione IRCCS Policlinico San Matteo, and Department of Molecular Medicine, University of Pavia, Pavia, Italy.
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Pires RH, Saraiva MJ, Damas AM, Kellermayer MS. Mechanical Features of Transthyretin: Probing Folding Intermediates of an Amyloid Forming Protein by Single Molecule Force Spectroscopy. Biophys J 2012. [DOI: 10.1016/j.bpj.2011.11.3140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Castro-Rodrigues AF, Gales L, Saraiva MJ, Damas AM. Structural insights into a zinc-dependent pathway leading to Leu55Pro transthyretin amyloid fibrils. Acta Crystallogr D Biol Crystallogr 2011; 67:1035-44. [PMID: 22120741 DOI: 10.1107/s090744491104491x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2011] [Accepted: 10/26/2011] [Indexed: 11/10/2022]
Abstract
Human transthyretin (TTR) is a homotetrameric protein that is responsible for the formation of amyloid in patients with familiar amyloidotic polyneuropathy (FAP), familiar amyloidotic cardiomyopathy (FAC) and senile systemic amyloidosis (SSA). Amyloid fibrils are characterized by a cross-β structure. However, details of how TTR monomers are organized to form such an assembly remain unknown. The effect of Zn(2+) in increasing TTR L55P amyloidogenecity has been reported. Crystals of the TTR L55P-Zn(2+) complex were grown under conditions similar to those leading to higher amyloidogenic potential of the variant protein and the three-dimensional structure of the complex was determined by X-ray crystallography. Two different tetrahedral Zn(2+)-binding sites were identified: one cross-links two tetramers, while the other lies at the interface between two monomers in a dimer. The association of monomers involving the two Zn(2+)-binding sites leads to a bidimensional array with a cross-β structure. The formation of this structure and subsequent organization into amyloid fibrils was monitored by fluorescence spectroscopy and electron microscopy. The TTR L55P-Zn(2+) structure offers the first molecular insights into the role of Zn(2+) as a mediator of cross-β-type structure in TTR amyloidosis and the relevance of a Zn(2+)-dependent pathway leading to the production of early amyloidogenic intermediates is discussed.
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Pires RH, Saraiva MJ, Damas AM, Kellermayer MSZ. Structure and assembly-disassembly properties of wild-type transthyretin amyloid protofibrils observed with atomic force microscopy. J Mol Recognit 2011; 24:467-76. [PMID: 21504025 DOI: 10.1002/jmr.1112] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Transthyretin (TTR) is an important human transport protein present in the serum and the cerebrospinal fluid. Aggregation of TTR in the form of amyloid fibrils is associated with neurodegeneration, but the mechanisms of cytotoxicity are likely to stem from the presence of intermediate assembly states. Characterization of these intermediate species is therefore essential to understand the etiology and pathogenesis of TTR-related amyloidoses. In the present work we used atomic force microscopy to investigate the morphological features of wild-type (WT) TTR amyloid protofibrils that appear in the early stages of aggregation. TTR protofibrils obtained by mild acidification appeared as flexible filaments with variable length and were able to bind amyloid markers (thioflavin T and Congo red). Surface topology and contour-length distribution displayed a periodic pattern of ∼ 15 nm, suggesting that the protofibrils assemble via an end-binding oligomer fusion mechanism. The average height and periodic substructure found in protofibrils is compatible with the double-helical model of the TTR amyloid protofilament. Over time protofibrils aggregated into bundles and did not form mature amyloid-like fibrils. Unlike amyloid fibrils that are typically stable under physiological conditions, the bundles dissociated into component protofibrils with axially compacted and radially dilated structure when exposed to phosphate-buffered saline solution. Thus, WT TTR can form metastable filamentous aggregates that may represent an important transient state along the pathway towards the formation of cytotoxic TTR species.
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Affiliation(s)
- Ricardo H Pires
- Department of Biophysics and Radiation Biology, Faculty of Medicine, Semmelweis University, Tűzoltó u. 37-47, Budapest IX, H1094 Hungary.
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Martinho A, Gonçalves I, Cardoso I, Almeida MR, Quintela T, Saraiva MJ, Santos CRA. Human metallothioneins 2 and 3 differentially affect amyloid-beta binding by transthyretin. FEBS J 2010; 277:3427-36. [PMID: 20646067 DOI: 10.1111/j.1742-4658.2010.07749.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Transthyretin (TTR), an amyloid-beta (Abeta) scavenger protein, and metallothioneins 2 and 3 (MT2 and MT3), low molecular weight metal-binding proteins, have recognized impacts in Abeta metabolism. Because TTR binds MT2, an ubiquitous isoform of the MTs, we investigated whether it also interacts with MT3, an isoform of the MTs predominantly expressed in the brain, and studied the role of MT2 and MT3 in human TTR-Abeta binding. The TTR-MT3 interaction was characterized by yeast two-hybrid assays, saturation-binding assays, co-immunolocalization and co-immunoprecipitation. The effect of MT2 and MT3 on TTR-Abeta binding was assessed by competition-binding assays. The results obtained clearly demonstrate that TTR interacts with MT3 with a K(d) of 373.7 +/- 60.2 nm. Competition-binding assays demonstrated that MT2 diminishes TTR-Abeta binding, whereas MT3 has the opposite effect. In addition to identifying a novel ligand for TTR that improves human TTR-Abeta binding, the present study highlights the need to clarify whether the effects of MT2 and MT3 in human TTR-Abeta binding observed in vitro have a relevant impact on Abeta deposition in animal models of Alzheimer's disease.
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Affiliation(s)
- Ana Martinho
- Health Sciences Research Centre, CICS, University of Beira Interior, Covilhã, Portugal
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28
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Costa R, Ferreira-da-Silva F, Saraiva MJ, Cardoso I. Transthyretin protects against A-beta peptide toxicity by proteolytic cleavage of the peptide: a mechanism sensitive to the Kunitz protease inhibitor. PLoS One 2008; 3:e2899. [PMID: 18682830 PMCID: PMC2483353 DOI: 10.1371/journal.pone.0002899] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2008] [Accepted: 07/14/2008] [Indexed: 01/26/2023] Open
Abstract
Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the deposition of amyloid beta-peptide (A-Beta) in the brain. Transthyretin (TTR) is a tetrameric protein of about 55 kDa mainly produced in the liver and choroid plexus of the brain. The known physiological functions of TTR are the transport of thyroid hormone T(4) and retinol, through binding to the retinol binding protein. TTR has also been established as a cryptic protease able to cleave ApoA-I in vitro. It has been described that TTR is involved in preventing A-Beta fibrilization, both by inhibiting and disrupting A-Beta fibrils, with consequent abrogation of toxicity. We further characterized the nature of the TTR/A-Beta interaction and found that TTR, both recombinant or isolated from human sera, was able to proteolytically process A-Beta, cleaving the peptide after aminoacid residues 1, 2, 3, 10, 13, 14,16, 19 and 27, as determined by mass spectrometry, and reversed phase chromatography followed by N-terminal sequencing. A-Beta peptides (1-14) and (15-42) showed lower amyloidogenic potential than the full length counterpart, as assessed by thioflavin binding assay and ultrastructural analysis by transmission electron microscopy. A-Beta cleavage by TTR was inhibited in the presence of an alphaAPP peptide containing the Kunitz Protease Inhibitor (KPI) domain but not in the presence of the secreted alphaAPP derived from the APP isoform 695 without the KPI domain. TTR was also able to degrade aggregated forms of A-Beta peptide. Our results confirmed TTR as a protective molecule in AD, and prompted A-Beta proteolysis by TTR as a protective mechanism in this disease. TTR may prove to be a useful therapeutic agent for preventing or retarding the cerebral amyloid plaque formation implicated in AD pathology.
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Affiliation(s)
- Rita Costa
- Molecular Neurobiology, IBMC (Instituto de Biologia Molecular e Celular), Porto, Portugal
| | | | - Maria J. Saraiva
- Molecular Neurobiology, IBMC (Instituto de Biologia Molecular e Celular), Porto, Portugal
- ICBAS, University of Porto, Porto, Portugal
| | - Isabel Cardoso
- Molecular Neurobiology, IBMC (Instituto de Biologia Molecular e Celular), Porto, Portugal
- * E-mail:
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29
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Abstract
Recently, a new transthyretin (TTR) variant was described in the normal Portuguese and German populations. The same substitution was found associated with familial amyloidotic polyneuropathy (FAP) in an American family of Italian origin. Comparative isoelectric focusing studies showed a difference in the mobility pattern between the non-pathogenic and pathogenic variants. However, comparative DNA sequencing between them did not reveal any additional mutation. Comparative isoelectric focusing between the variants and TTR Asn 90 produced by recombinant techniques indicated that the non-pathogenic variant has the electrophoretic behaviour expected for the mutation. We suggest that an as yet unknown post-translational modification may have occurred in the FAP-associated Asn 90 variant, turning it into an amyloidogenic molecule.
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Affiliation(s)
- I L Alves
- Centro de Estudos de Paramiloidose, Hosp. Sto António, Porto, Portugal
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30
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Costa R, Gonçalves A, Saraiva MJ, Cardoso I. Transthyretin binding to A-Beta peptide--impact on A-Beta fibrillogenesis and toxicity. FEBS Lett 2008; 582:936-42. [PMID: 18295603 DOI: 10.1016/j.febslet.2008.02.034] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 01/31/2008] [Accepted: 02/11/2008] [Indexed: 11/25/2022]
Abstract
It has been suggested that transthyretin (TTR) is involved in preventing A-Beta fibrillization in Alzheimer's disease (AD). Here, we characterized the TTR/A-Beta interaction by competition binding assays. TTR binds to different A-Beta peptide species: soluble (Kd, 28 nM), oligomers and fibrils; diverse TTR variants bind differentially to A-Beta. Transmission electron microscopy (TEM) analysis demonstrated that TTR is capable of interfering with A-Beta fibrillization by both inhibiting and disrupting fibril formation. Co-incubation of the two molecules resulted in the abolishment of A-Beta toxicity. Our results confirmed TTR as an A-Beta ligand and indicated the inhibition/disruption of A-Beta fibrils as a possible mechanism underlying the protective role of TTR in AD.
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Affiliation(s)
- R Costa
- Molecular Neurobiology Unit, Instituto de Biologia Molecular e Celular, Rua do Campo Alegre, 823, 4150-180 Porto, Portugal
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31
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Santos SD, Cardoso I, Magalhães J, Saraiva MJ. Impairment of the ubiquitin-proteasome system associated with extracellular transthyretin aggregates in familial amyloidotic polyneuropathy. J Pathol 2007; 213:200-9. [PMID: 17724793 DOI: 10.1002/path.2224] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ubiquitin-proteasome system (UPS) has been associated with neurodegenerative disorders of intracellular protein aggregation. We have studied the UPS in familial amyloidotic polyneuropathy (FAP), a neurodegenerative disorder caused by extracellular deposition of mutant transthyretin (TTR). The studies were conducted in TTR-synthesizing and non-synthesizing tissues from affected individuals, in transgenic mouse models for FAP, and in neuronal or Schwannoma cell lines cultured with TTR aggregates. In human FAP tissues presenting extracellular TTR aggregates, ubiquitin-protein conjugates were up-regulated, the proteasome levels were decreased and parkin and alpha-synuclein expression were both decreased. A similar response was detected in mouse models for TTR V30M or L55P. On the other hand, the liver, which normally synthesizes variant TTR V30M, did not show this response. Furthermore, transgenic mice immunized to decrease TTR deposition showed a significant reduction in ubiquitin levels and an increase in parkin and alpha-synuclein levels in comparison to control mice. Studies performed in cell lines with aggregates in the medium resulted in increased ubiquitin and decreased parkin levels. The overall results are indicative of TTR deposition as an external stimulus to an intracellular UPS response in FAP.
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Affiliation(s)
- S D Santos
- Molecular Neurobiology Unit, Institute of Molecular and Cell Biology, University of Porto, Portugal
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32
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Ruano D, Macedo A, Soares MJ, Valente J, Azevedo MH, Hutz MH, Gama CS, Lobato MI, Belmonte-de-Abreu P, Goodman AB, Pato C, Saraiva MJ, Heutink P, Palha JA. Transthyretin: no association between serum levels or gene variants and schizophrenia. J Psychiatr Res 2007; 41:667-72. [PMID: 16716350 DOI: 10.1016/j.jpsychires.2006.04.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2005] [Revised: 03/13/2006] [Accepted: 04/04/2006] [Indexed: 11/18/2022]
Abstract
It has been proposed that schizophrenia results from an environmental insult in genetically predisposed individuals. Environmental factors capable of modulating transcriptional activity and their carriers could link the genetic and environmental components of schizophrenia. Among these is transthyretin (TTR), a major carrier of thyroid hormones and retinol-binding protein (RBP). Retinoids and thyroid hormones regulate the expression of several genes, both during development and in the adult brain. Decreased TTR levels have been reported in the cerebrospinal fluid of patients with depression and Alzheimer's disease, and the absence of TTR influences behavior in mice. DNA variants capable of altering TTR ability to carry its ligands, either due to reduced transcription of the gene or to structural modifications of the protein, may influence development of the central nervous system and behavior. In the present study we searched for variants in the regulatory and coding regions of the TTR gene, and measured circulating levels of TTR and RBP. We found a novel single nucleotide polymorphism (SNP), ss46566417, 18 bp upstream of exon 4. Neither this SNP nor the previously described rs1800458 were found associated with schizophrenia. In addition, serum TTR and RBP levels did not differ between mentally healthy and schizophrenic individuals. In conclusion, our data does not support an involvement of the TTR gene in the pathophysiology of schizophrenia.
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Affiliation(s)
- Dina Ruano
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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Saraiva MJ, Almeida MR, Alves IL, Bonifácio MJ, Damas AM, Palha JA, Goldsteins G, Lundgren E. Modulating conformational factors in transthyretin amyloid. Ciba Found Symp 2007; 199:47-52; discussion 52-7. [PMID: 8915603 DOI: 10.1002/9780470514924.ch4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We have analysed the structure, binding properties, stability and amyloidogenicity of particular transthyretin (TTR) mutations-TTR Met30 and TTR Pro55, both associated with familial amyloid polyneuropathy, and TTR Met119, a non-pathogenic TTR mutation with apparent protective effects on the amyloidogenicity of the Met30 mutation. Our results show that in contrast to the Met30 mutation, the Met119 mutation increases the stability of the tetramer towards dissociation into monomers and confers a higher affinity to thyroxine, which binds on the channel that runs through the tetramer. This variant also shows a greater resistance to amyloid formation in vitro, in contrast to the Pro55 variant, which is more susceptible to amyloid formation. Crystallographic studies of the structure of the Pro55 variant are underway and reveal major conformational changes. Interestingly, these changes affect the D strand of TTR, which when deleted or modified in vitro leads to accelerated rates of amyloid formation. The conformational changes observed in these "aggressive' mutations may resemble intermediate forms in the process of amyloidogenesis.
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Affiliation(s)
- M J Saraiva
- Centro de Estudos de Paramiloidose, Hospital de Sto. Antonio, Porto, Portugal
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Abstract
The increasing knowledge of the exact biochemical nature of the localized and systemic amyloid disorders has made a logical and easily understood nomenclature absolutely necessary. Such a nomenclature, biochemically based, has been used for several years but the current literature is still mixed up with many clinical and histochemically based designations from the time when amyloid in general was poorly understood. All amyloid types are today preferably named by their major fibril protein. This makes a simple and rational nomenclature for the increasing number of amyloid disorders known in humans and animals.
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Affiliation(s)
- Per Westermark
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden.
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35
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Choi SH, Leight SN, Lee VMY, Li T, Wong PC, Johnson JA, Saraiva MJ, Sisodia SS. Accelerated Abeta deposition in APPswe/PS1deltaE9 mice with hemizygous deletions of TTR (transthyretin). J Neurosci 2007; 27:7006-10. [PMID: 17596449 PMCID: PMC6672232 DOI: 10.1523/jneurosci.1919-07.2007] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A cardinal pathological lesion of Alzheimer's disease (AD) is the deposition of amyloid beta (Abeta) in the brain. We previously reported that exposing transgenic mice harboring APPswe/PS1deltaE9 transgenes to an enriched environment resulted in reduced levels of Abeta peptides and deposition, findings that were correlated with an increase in the expression of TTR, encoding transthyretin (TTR). TTR is expressed at high levels in the choroid plexus and known to bind Abeta peptides and modulate their aggregation in vitro and in vivo. To explore the impact of TTR expression on Abeta levels and deposition in vivo, we crossed ceAPPswe/PS1deltaE9 transgenic mice to mice with genetic ablations of TTR. We now report that the levels of detergent-soluble and formic acid-soluble levels of Abeta and deposition are elevated in the brains of ceAPPswe/PS1deltaE9/TTR+/- mice compared with age-matched ceAPPswe/PS1deltaE9/TTR+/+ mice. Moreover, Abeta deposition is significantly accelerated in the hippocampus and cortex of ceAPPswe/PS1deltaE9/TTR+/- mice. Our results strongly suggest that TTR plays a critical role in modulating Abeta deposition in vivo.
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Affiliation(s)
| | - Susan N. Leight
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Virginia M.-Y. Lee
- Department of Pathology and Laboratory Medicine, Center for Neurodegenerative Disease Research, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104
| | - Tong Li
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Philip C. Wong
- Department of Pathology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205
| | - Jeffrey A. Johnson
- Neuroscience Training Program, University of Wisconsin, Madison, Wisconsin 53705, and
| | | | - Sangram S. Sisodia
- Department of Neurobiology, University of Chicago, Chicago, Illinois 60637
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36
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Abstract
Mutations in transthyretin (TTR) are associated with familial amyloid polyneuropathy, a neurodegenerative disorder characterized by TTR deposition in the PNS. The aim of this study was to unravel whether TTR has a role in nerve physiology that could account for its preferential accumulation in the PNS, when mutated. The sensorimotor performance of wild-type and TTR knockout (KO) littermate mice was compared and showed impairment in mice lacking TTR. Given the possibility that, upon regeneration, the consequences arising from TTR absence might be exacerbated, nerve crush was performed in both strains. TTR KO mice presented delayed functional recovery resulting from decreased number of myelinated and unmyelinated fibers. Moreover, in transgenic mice in a TTR KO background, expressing human TTR in neurons, this phenotype was rescued, reinforcing that TTR enhances nerve regeneration. In vitro assays showed that neurite outgrowth and extension were decreased in the absence of TTR, probably underlying the decreased number of regenerating axons in TTR KO mice. Our findings demonstrate that TTR participates in nerve physiology and that it enhances nerve regeneration. Moreover, the assignment of a TTR function in nerve biology and repair, may explain its preferential deposition, when mutated, in the PNS of familial amyloid polyneuropathy patients.
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Affiliation(s)
- Carolina E Fleming
- Instituto de Biologia Molecular e Celular--IBMC, Molecular Neurobiology Group, Porto, Portugal
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37
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Altland K, Benson MD, Costello CE, Ferlini A, Hazenberg BPC, Hund E, Kristen AV, Linke RP, Merlini G, Salvi F, Saraiva MJ, Singer R, Skinner M, Winter P. Genetic microheterogeneity of human transthyretin detected by IEF. Electrophoresis 2007; 28:2053-64. [PMID: 17503405 DOI: 10.1002/elps.200600840] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mutations of the human transthyretin (TTR) gene have attracted medical interest as a cause of amyloidosis. Recently, we have described in detail an electrophoretic procedure with PAGE followed by IEF in urea gradients for the study of the microheterogeneity of TTR monomers (Altland, K., Winter, P., Sauerborn, M. K., Electrophoresis 1999, 20, 1349-1364). In this paper, we present a study on 49 different mutations of TTR including 33 that result in electrically neutral amino acid substitutions. The aims of the investigation were to test the sensitivity of the procedure to detect TTR variants in patients with TTR amyloidosis and their relatives and to identify some common characteristics that could explain the amyloidogenicity of these variants. We found that all tested amyloidogenic mutations could be detected by our method with the exception of those for which the corresponding variant was absent in plasma samples. Most of the electrically neutral amyloidogenic TTR variants had in common a reduced conformational stability of monomers by the activity of protons and urea. For three variants, e.g. TTR-F64L, TTR-I107V and TTR-V122I, the monomers had a conformational stability close to that of normal monomers but we found experimental and structural arguments for a weakening of the monomer-monomer contact. All types of amyloidogenic mutations affected the stability of TTR tetramers.
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Affiliation(s)
- Klaus Altland
- Institut für Humangenetik, Justus-Liebig-Universität, Giessen, Germany.
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Gales L, Saraiva MJ, Damas AM. Structural basis for the protective role of sulfite against transthyretin amyloid formation. Biochim Biophys Acta 2006; 1774:59-64. [PMID: 17175208 DOI: 10.1016/j.bbapap.2006.10.015] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2006] [Revised: 10/10/2006] [Accepted: 10/26/2006] [Indexed: 11/20/2022]
Abstract
Transthyretin (TTR) is a plasma protein, which under conditions not yet completely understood, aggregates forming amyloid deposits that occur extracellularly. It is a protein composed of four identical subunits. Each monomer has a single cysteine residue (Cys10), which in the plasma is reduced (Cys-SH), oxidized (Cys-SO3-), sulfonated (Cys-S-SO3-) or bound to various sulfhydryls. There is evidence that these chemical modifications of the SH group alter the stability and the amyloidogenic potential of the protein. The sulfonated form was found to enhance the stability of the native conformation of TTR, avoiding misassembly of the protein leading to amyloid. Consequently, the potential treatment of TTR-type amyloidosis by sulfite has been suggested. The structure of TTR pre-incubated with sulfite at physiological pH, was determined by X-ray crystallography to provide structural insight for the stabilizing effect of sulfite. Each subunit has a beta-sandwich conformation, with two four stranded beta-pleated sheets (DAGH and CBEF) and a small alpha-helix between strands. The sulfonated cysteines have two sulfite oxygens involved in intramonomer hydrogen bonds that bridge Cys10, the amino acid immediately before beta-strand A, to the amino acids immediately after the edge beta-strand D. Implications of the newly observed interactions in the inhibition of fibril formation are discussed in light of the recent structural models of TTR amyloid fibrils.
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Affiliation(s)
- Luís Gales
- Unidade de Estrutura Molecular, IBMC- Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
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Morais-de-Sá E, Neto-Silva RM, Pereira PJB, Saraiva MJ, Damas AM. The binding of 2,4-dinitrophenol to wild-type and amyloidogenic transthyretin. Acta Crystallogr D Biol Crystallogr 2006; 62:512-9. [PMID: 16627944 DOI: 10.1107/s0907444906006962] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2006] [Accepted: 02/25/2006] [Indexed: 11/10/2022]
Abstract
Systemic deposition of transthyretin (TTR) amyloid fibrils is always observed in familial amyloidotic polyneuropathy, senile systemic amyloidosis and familial amyloidotic cardiomyopathy patients. Destabilization of the molecule leads to a cascade of events which result in fibril formation. The destabilization of a native protein with consequent conformational changes appears to be a common link in several human amyloid diseases. Intensive research has been directed towards finding small molecules that could work as therapeutic agents for the prevention/inhibition of amyloid diseases through stabilization of the native fold of the potentially amyloidogenic protein. This work provides insight into the structural determinants of the highly stabilizing effects of 2,4-dinitrophenol on wild-type TTR. It is also shown that similar interactions are established between this molecule and two highly amyloidogenic TTR variants: TTR L55P and TTR Y78F. In the three crystal complexes, 2,4-dinitrophenol occupies the two hormone-binding sites of the TTR tetramer. As a result of 2,4-dinitrophenol binding, the two dimers in the TTR tetramer become closer, increasing the stability of the protein. The three-dimensional structures now determined allow a comprehensive description of key interactions between transthyretin and 2,4-dinitrophenol, a small compound that holds promise as a template for the design of a therapeutical drug for amyloid diseases.
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Affiliation(s)
- Eurico Morais-de-Sá
- Instituto de Biologia Molecular e Celular-IBMC, Rua do Campo Alegre 823, 4150-180 Porto, Portugal
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40
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Abstract
Familial amyloidotic polyneuropathy (FAP) is a neurodegenerative disorder characterized by the extracellular deposition of transthyretin (TTR), especially in the PNS. Given the invasiveness of nerve biopsy, salivary glands (SG) from FAP patients were used previously in microarray analysis; mitogen-activated protein (MAP) kinase phosphatase 1 (MKP-1) was down-regulated in FAP. Results were validated by RT-PCR and immunohistochemistry both in SG and in nerve biopsies of different stages of disease progression. MKP-3 was also down-regulated in FAP SG biopsies. Given the relationship between MKPs and MAPKs, the latter were investigated. Only extracellular signal-regulated kinases 1/2 (ERK1/2) displayed increased activation in FAP SG and nerves. ERK1/2 kinase (MEK1/2) activation was also up-regulated in FAP nerves. In addition, an FAP transgenic mouse model revealed increased ERK1/2 activation in peripheral nerve affected with TTR deposition when compared to control animals. Cultured rat Schwannoma cell line treatment with TTR aggregates stimulated ERK1/2 activation, which was partially mediated by the receptor for advanced glycation end-products (RAGE). Moreover, caspase-3 activation triggered by TTR aggregates was abrogated by U0126, a MEK1/2 inhibitor, indicating that ERK1/2 activation is essential for TTR aggregates-induced cytotoxicity. Taken together, these data suggest that abnormally sustained activation of ERK in FAP may represent an early signaling cascade leading to neurodegeneration.
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Affiliation(s)
- F A Monteiro
- Molecular Neurobiology, Instituto de Biologia Celular e Molecular, ICBAS, University of Porto, and Estomatology, Maxillofacial Surgery, Hospital Geral de Santo António, Portugal
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41
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Abstract
Familial amyloidotic polyneuropathy is an autosomal dominant disorder mainly characterized by the extracellular deposition of transthyretin, with special involvement of the peripheral nerve. Several animal models have been generated, including transgenic mice carrying the most prevalent TTR mutation (TTR Val30Met). TTR-Val30Met mice without endogenous TTR (TTR-Val30Met X TTR-KO) were previously analyzed in our laboratory and approximately 60% of the animals over 1 year of age were found to have deposition as amyloid, i.e., with Congo red (CR) -positive material, constituting a good tool to investigate the effect of drugs on TTR deposition and fibrillogenesis. We recently showed that the drug doxycycline acts in vitro as a TTR fibril disrupter. In the present work we assessed the activity of this drug in vivo in the TTR-Met30Val X TTR-KO mice. Doxycycline was administrated in the drinking water to 23- to 28-month-old mice over a period of 3 months. Immunohistochemistry analyses revealed no differences in nonfibrillar TTR deposition between treated (n=11) and untreated mice (n=11). However, CR-positive material was observed only in the control group (untreated) whereas none of the animals treated with doxycycline was CR-positive. Immunohistochemistry for several markers associated with amyloid, such as matrix metalloproteinase-9 (MMP-9) and serum amyloid P component (SAP), was performed. MMP-9 was altered with significantly lower levels in treated animals compared with the control group. Mouse SAP was absent in treated animals, being observed only in untreated animals presenting TTR congophilic deposits. These results indicate that doxycycline is capable of disrupting TTR CR-positive amyloid deposits and decreases standard markers associated with fibrillar deposition, being a potential drug in the treatment of amyloidosis.
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Affiliation(s)
- I Cardoso
- Molecular Neurobiology, IBMC, Porto University, Porto, Portugal
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42
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Terazaki H, Ando Y, Fernandes R, Yamamura KI, Maeda S, Saraiva MJ. Immunization in familial amyloidotic polyneuropathy: counteracting deposition by immunization with a Y78F TTR mutant. J Transl Med 2006; 86:23-31. [PMID: 16357867 DOI: 10.1038/labinvest.3700365] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
The mechanism of amyloid formation in familial amyloidotic polyneuropathy (FAP), a hereditary disorder associated with mutant transthyretin (TTR), is still unknown. It is generally believed that altered conformations exposing cryptic regions are intermediary steps in this mechanism. A TTR mutant--Y78F (transthyretin mutant with phenylalanine replacing tyrosine at position 78)--designed to destabilize the native structure has been shown to expose a cryptic epitope recognized by a monoclonal antibody that reacts only with highly amyloidogenic mutants presenting the amyloid fold or with amyloid fibrils. To test whether TTR deposition in FAP can be counteracted by antibodies for cryptic epitopes, we immunized with TTR Y78F, transgenic mice carrying the most common FAP-associated TTR mutant--V30M (transthyretin mutant with methionine replacing valine at position 30)--at selected ages that present normally with either nonfibrillar or TTR amyloid deposition. Compared to age-matched control nonimmunized mice, Y78F-immunized mice had a significant reduction in TTR deposition usually found in this strain, in particular in stomach and intestine; by contrast, animals immunized with V30M did not show differences in deposition in comparison with nonimmunized mice. Immunohistochemical analyses of tissues revealed that immunization with Y78F lead to infiltration by lymphocytes and macrophages at common deposition sites, but not in tissues such as liver, choroid plexus, and Langerhans islets, in which TTR is produced. These results suggest that Y78F induced production of an antibody that reacts specifically with deposits and leads to an immune response effective in removing/preventing TTR deposition. Therefore, TTR immunization with selected TTR mutants has potential application in immune therapy for FAP.
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Affiliation(s)
- Hisayasu Terazaki
- Molecular Neurobiology, Institute for Molecular and Cell Biology, University of Porto, Porto, Portugal
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Maia F, Almeida MDR, Gales L, Kijjoa A, Pinto MMM, Saraiva MJ, Damas AM. The binding of xanthone derivatives to transthyretin. Biochem Pharmacol 2005; 70:1861-9. [PMID: 16236271 DOI: 10.1016/j.bcp.2005.09.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Revised: 09/09/2005] [Accepted: 09/12/2005] [Indexed: 11/23/2022]
Abstract
A series of xanthone derivatives, isolated from Calophyllum teysmannii var. inophylloide, have been evaluated for their binding affinity to transthyretin. Transthyretin is a plasma protein involved in the transport of thyroxine (T4) and also implicated in amyloid diseases. Using competition-binding studies with the protein natural ligand T4, we have identified one prenylated xanthone with a very strong affinity to transthyretin. Molecular docking simulations show that the flexible tail of the prenylated xanthone could allow favorable molecular interactions. Since this xanthone may play a role in the thyroxine metabolism and/or over the pathogenic process associated with the amyloid disease, these results may be explored for the design of new ligands.
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Affiliation(s)
- Filipe Maia
- Unidade de Estrutura Molecular, IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
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Sousa JC, de Escobar GM, Oliveira P, Saraiva MJ, Palha JA. Transthyretin is not necessary for thyroid hormone metabolism in conditions of increased hormone demand. J Endocrinol 2005; 187:257-66. [PMID: 16293773 DOI: 10.1677/joe.1.06406] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Thyroid hormones circulate in blood mainly bound to plasma proteins. Transthyretin is the major thyroxine plasma carrier in mice. Studies in transthyretin-null mice revealed that the absence of transthyretin results in euthyroid hypothyroxinemia and normal thyroid hormone tissue distribution, with the exception of the choroid plexus in the brain. Therefore, transthyretin does not influence normal thyroid hormone homeostasis under standard laboratory conditions. To investigate if transthyretin has a buffer/storage role we challenged transthyretin-null and wild-type mice with conditions of increased hormone demand: (i) exposure to cold, which elicits thermogenesis, a process that requires thyroid hormones; and (ii) thyroidectomy, which abolishes thyroid hormone synthesis and secretion and induces severe hypothyroidism. Transthyretin-null mice responded as the wild-type both to changes induced by stressful events, namely in body weight, food intake and thyroid hormone tissue content, and in the mRNA levels of genes whose expression is altered in such conditions. These results clearly exclude a role for transthyretin in thyroid hormone homeostasis even under conditions of increased hormone demand.
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Affiliation(s)
- J C Sousa
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus Gualtar, Braga, Portugal
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Abstract
In transthyretin (TTR) amyloidosis TTR variants deposit as amyloid fibrils giving origin, in most cases, to peripheral polyneuropathy, cardiomyopathy, carpal tunnel syndrome and/or amyloid deposition in the eye. More than eighty TTR variants are known, most of them being pathogenic. The mechanism of TTR fibril formation is still not completely elucidated. However it is widely accepted that the amino acid substitutions in the TTR variants contribute to a destabilizing effect on the TTR tetramer molecule, which in particular conditions dissociate into non native monomeric intermediates that aggregate and polymerize in amyloid fibrils that further elongate. Since this is a multi-step process there is the possibility to impair TTR amyloid fibril formation at different stages of the process namely by tetramer stabilization, inhibition of fibril formation or fibril disruption. Till now the only efficient therapy available is liver transplant when performed in an early phase of the onset of the disease symptoms. Since this is a very invasive therapy alternatives are desirable. In that sense, several compounds have been proposed to impair amyloid formation or disruption. Based on the proposed mechanism for TTR amyloid fibril formation we discuss the action of some of the proposed TTR stabilizers such as derivatives of some NSAIDs (diflunisal, diclofenac, flufenamic acid, and derivatives) and the action of amyloid disrupters such as 4'-iodo-4'-deoxydoxorubicin (I-DOX) and tetracyclines. Among all these compounds, TTR stabilizers seem to be the most interesting since they would impair very early the process of amyloid formation and could also have a prophylactic effect.
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Affiliation(s)
- M R Almeida
- ICBAS - Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4099-003 Porto, Portugal
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Westermark P, Benson MD, Buxbaum JN, Cohen AS, Frangione B, Ikeda SI, Masters CL, Merlini G, Saraiva MJ, Sipe JD. Amyloid: toward terminology clarification. Report from the Nomenclature Committee of the International Society of Amyloidosis. Amyloid 2005; 12:1-4. [PMID: 16076605 DOI: 10.1080/13506120500032196] [Citation(s) in RCA: 220] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The modern nomenclature of amyloidosis now includes 25 human and 8 animal fibril proteins. To be included in the list, the protein has to be a major fibril protein in extracellular deposits, which have the characteristics of amyloid, including affinity for Congo red with resulting green birefringence. Synthetic fibrils with amyloid properties are best named 'amyloid-like'. With increasing knowledge, however, the borders between different protein aggregates tend to become less sharp.
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Affiliation(s)
- Per Westermark
- Department of Genetics and Pathology, Uppsala University, Uppsala, Sweden.
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Neto-Silva RM, Macedo-Ribeiro S, Pereira PJB, Coll M, Saraiva MJ, Damas AM. X-ray crystallographic studies of two transthyretin variants: further insights into amyloidogenesis. Acta Crystallogr D Biol Crystallogr 2005; 61:333-9. [PMID: 15735344 DOI: 10.1107/s0907444904034316] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2004] [Accepted: 12/23/2004] [Indexed: 11/10/2022]
Abstract
Transthyretin (TTR) is a homotetrameric plasma protein that, as a result of a set of not yet fully characterized conformational changes, forms fibrillar aggregates that are the major protein component of amyloid deposits. More than 80 mutations associated with TTR amyloid deposition have been described in the literature. X-ray crystallography was used to elucidate the three-dimensional structure of two important TTR variants: TTR Y78F, an amyloidogenic protein, and TTR R104H, which is associated with a protective effect over the amyloidogenic V30M mutation. The structures of those two TTR variants have been determined in space group P2(1)2(1)2 to 1.55 and 1.60 angstroms resolution, respectively, using molecular-replacement techniques. Detailed analysis of the protein model for TTR Y78F indicates a destabilization of the contacts between the alpha-helix and AB loop and the body of the molecule, intimately related to the amyloidogenic nature; contrastingly, in the TTR R104H variant new contacts involving the N-terminal region and His104 are clearly antagonists of amyloid formation.
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Affiliation(s)
- Ricardo M Neto-Silva
- Molecular Structure Group, Institute for Molecular and Cell Biology, Rua do Campo Alegre No. 823, 4150 Porto, Portugal
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Damas AM, Ribeiro S, Lamzin VS, Palha JA, Saraiva MJ. Structure of the Val122Ile variant transthyretin - a cardiomyopathic mutant. Acta Crystallogr D Biol Crystallogr 2005; 52:966-72. [PMID: 15299606 DOI: 10.1107/s0907444996003307] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The Val122Ile mutant transthyretin (TTR Ile122) is an amyloidogenic protein which has been described as the major protein component of amyloid fibrils isolated from patients with familial amyloidotic cardiomyopathy (FAC), a disease characterized by cardiac failure and amyloid deposits in the heart. The reasons for the deposition of TTR are still unknown and it is conceivable that a conformational alteration, resulting from the mutation, is fundamental for amyloid formation. The three-dimensional structure of TTR Ile122 was determined and refined to a crystallographic R factor of 15.8% at 1.9 A resolution. The r.m.s. deviation from ideality in bond distances is 0.019 A and in angle-bonded distances is 0.027 A. The presence of two crystallographically independent monomers in the asymmetric unit allowed additional means of estimation of atomic coordinate error. The structure of the mutant is essentially identical to that of the wild-type transthyretin (TTR). The largest deviations occur in surface loops and in the region of the substitution. The protein is a tetramer composed of identical subunits; each monomer has two four-stranded beta-sheets which are extended to eight-stranded beta-sheets when two monomers associate through hydrogen bonds forming a dimer, which is the crystallographic asymmetric unit. The replacement of valine for isoleucine introduces very small alterations in relation to the wild-type protein; nevertheless they seem to confirm a tendency for a less stable tetrameric structure. This would support the idea that the tetrameric structure might be disrupted in amyloid fibrils.
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Affiliation(s)
- A M Damas
- Instituto de Ciências Biomédicas Abel Salazar, Universidade do Porto, Portugal.
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Abstract
Transthyretin (TTR) is a homotetrameric plasma protein that, in conditions not yet completely understood, may aggregate, forming the fibrillar material associated with TTR amyloidosis. A number of reported experiments indicate that dissociation of the TTR tetramer occurs prior to fibril formation, and therefore, studies aiming at the discovery of compounds that stabilize the protein quaternary structure, thereby acting as amyloid inhibitors, are being performed. The ability of diethylstilbestrol (DES) to act as a competitive inhibitor for the thyroid hormone binding to TTR indicated a possible stabilizing effect of DES upon binding. Here we report the crystallographic study of DES binding to TTR. The structural data reveal two different binding modes, both located in the thyroxine binding channel. In both cases, DES binds deeply in the channel and establishes interactions with the equivalent molecule present in the adjacent binding site. The most remarkable features of DES interaction with TTR are its hydrophobic interactions within the protein halogen binding pockets, where its ethyl groups are snugly fitted, and the hydrogen bonds established at the center of the tetramer with Ser-117. Experiments concerning amyloid formation in vitro suggest that DES is effectively an amyloid inhibitor in acid-mediated fibrillogenesis and may be used for the design of more powerful drugs. The present study gave us further insight in the molecular mechanism by which DES competes with thyroid hormone binding to TTR and highlights key interactions between DES and TTR that oppose amyloid formation.
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Affiliation(s)
- Eurico Morais-de-Sá
- Molecular Structure and Molecular Neurobiology, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre, Number 823, 4150 Porto, Portugal
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Abstract
Heat shock transcription factors mediate the regulation of the organism physiological maintenance and adaptation. We investigated the morphology and cellular expression of selected genes in brains of transgenic mice lacking the heat shock transcription factor 1, HSF1, the main transactivator under stress conditions. All HSF1 null mice displayed major brain morphological alterations: the lateral ventricles were markedly enlarged and the white matter reduced, as in ventriculomegaly. Heterozygous mice for the HSF1 gene also had these abnormalities albeit to a lower extent in comparison to the wild type, indicating a gene dosage effect. Cell loss, vacuolisation, amorphous eosinophilic cytoplasm and pyknotic nucleus were evident in the white matter, especially in periventricular regions. These areas also exhibited astrogliosis and neurodegeneration. The expression of heat shock protein hsp 27 was up-regulated whereas alpha B-crystallin was down-regulated in different areas of HSF1 null mouse brain in comparison to control mice. These data implicate HSF1 in maintaining the postnatal mammalian brain under non-stress conditions.
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Affiliation(s)
- S D Santos
- Molecular Neurobiology Unit, Institute for Molecular and Cell Biology, Rua do Campo Alegre 8823, Porto, Portugal
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