Recognition of carbohydrate by major histocompatibility complex class I-restricted, glycopeptide-specific cytotoxic T lymphocytes

6 pages, 5 figures.-- PMID: 8046349 [PubMed].-- PMCID: PMC2191607.Cytotoxic T cells (CTL) recognize short peptide epitopes presented by class I glycoproteins encoded by the major histocompatibility complex (MHC). It is not yet known whether peptides containing posttranslationally modified amino acids can also be recognized by CTL. To address this issue, we have studied the immunogenicity and recognition of a glycopeptide carrying an O-linked N-acetylglucosamine (GlcNAc) monosaccharide-substituted serine residue. This posttranslational modification is catalyzed by a recently described cytosolic glycosyltransferase. We show that glycosylation does not affect peptide binding to MHC class I and that glycopeptides can elicit a strong CTL response that is glycopeptide specific. Furthermore, glycopeptide recognition by cytotoxic T cells is dependent on the chemical structure of the glycan as well as its position within the peptide.We wish to thank Dr. Elena Sadovnikova and Dr. Hans J. Stanss (Imperial Cancer Research Foundation, London, UK) for their valuable help with raising antipeptide CTLs; and Professor Jens Chr. Jensenius (University of Aarbus, Denmark) for helpful discussions. J. S. Haurum is a Carlsberg-Wellcome Travelling Research Fellow, G. Asequell is an EC Fellow, and A. C. Lellouch is supported by a United States Public Health Service National Research Service Award F32 GM- 15811. This work was supported by the Carlsberg Foundation, the Wellcome trust, the Beckett Foundation, and Statens Sundhedsvidenskabelige Forskningsr~d, Denmark.Peer reviewe

Oral Treatment with Iododiflunisal Delays Hippocampal Amyloid-β Formation in a Transgenic Mouse Model of Alzheimer's Disease: A Longitudinal in vivo Molecular Imaging Study

Transthyretin (TTR) is a tetrameric, amyloid-β (Aβ)-binding protein, which reduces Aβ toxicity. The TTR/Aβ interaction can be enhanced by a series of small molecules that stabilize its tetrameric form. Hence, TTR stabilizers might act as disease-modifying drugs in Alzheimer's disease. Objective: We monitored the therapeutic efficacy of two TTR stabilizers, iododiflunisal (IDIF), which acts as small-molecule chaperone of the TTR/Aβ interaction, and tolcapone, which does not behave as a small-molecule chaperone, in an animal model of Alzheimer's disease using positron emission tomography (PET). Methods: Female mice (AβPPswe/PS1A246E/TTR+/-) were divided into 3 groups (n=7 per group): IDIF-treated, tolcapone-treated, and non-treated. The oral treatment (100mg/Kg/day) was started at 5 months of age. Treatment efficacy assessment was based on changes in longitudinal deposition of Aβ in the hippocampus (HIP) and the cortex (CTX) and determined using PET-[18F]florbetaben. Immunohistochemical analysis was performed at age=14 months. Results: Standard uptake values relative to the cerebellum (SUVr) of [18F]florbetaben in CTX and HIP of non-treated animals progressively increased from age=5 to 11 months and stabilized afterwards. In contrast, [18F]florbetaben uptake in HIP of IDIF-treated animals remained constant between ages=5 and 11 months and significantly increased at 14 months. In the tolcapone-treated group, SUVr progressively increased with time, but at lower rate than in the non-treated group. No significant treatment effect was observed in CTX. Results from immunohistochemistry matched the in vivo data at age=14 months. Conclusion: Our work provides encouraging preliminary results on the ability of small-molecule chaperones to ameliorate Aβ deposition in certain brain regions

Longitudinal evaluation of neuroinflammation and oxidative stress in a mouse model of Alzheimer disease using positron emission tomography

[EN] Background: Validation of new biomarkers of Alzheimer disease (AD) is crucial for the successful development and implementation of treatment strategies. Additional to traditional AT(N) biomarkers, neuroinflammation biomarkers, such as translocator protein (TSPO) and cystine/glutamine antiporter system (x(c)(-)), could be considered when assessing AD progression. Herein, we report the longitudinal investigation of [F-18]DPA-714 and [F-18]FSPG for their ability to detect TSPO and x(c)(-) biomarkers, respectively, in the 5xFAD mouse model for AD. Methods: Expression of TSPO and x(c)(-) system was assessed longitudinally (2-12 months of age) on 5xFAD mice and their respective controls by positron emission tomography (PET) imaging using radioligands [F-18]DPA-714 and [F-18]FSPG. In parallel, in the same mice, amyloid-beta plaque deposition was assessed with the amyloid PET radiotracer [F-18]florbetaben. In vivo findings were correlated to ex vivo immunofluorescence staining of TSPO and x(c)(-) in microglia/macrophages and astrocytes on brain slices. Physiological changes of the brain tissue were assessed by magnetic resonance imaging (MRI) in 12-month-old mice. Results: PET studies showed a significant increase in the uptake of [F-18]DPA-714 and [F-18]FSPG in the cortex, hippocampus, and thalamus in 5xFAD but not in WT mice over time. The results correlate with A beta plaque deposition. Ex vivo staining confirmed higher TSPO overexpression in both, microglia/macrophages and astrocytes, and overexpression of x(c)(-) in non-glial cells of 5xFAD mice. Additionally, the results show that A beta plaques were surrounded by microglia/macrophages overexpressing TSPO. MRI studies showed significant tissue shrinkage and microstructural alterations in 5xFAD mice compared to controls. Conclusions: TSPO and x(c)(-) overexpression can be assessed by [F-18]DPA-714 and [F-18]FSPG, respectively, and correlate with the level of A beta plaque deposition obtained with a PET amyloid tracer. These results position the two tracers as promising imaging tools for the evaluation of disease progression.J.L. and P.R. thank the Spanish Ministry of Science and Innovation MCIN/AEI/10.13039/501100011033 (PID2020-117656RB-100 and PID2020-118546RBI00, respectively) and the Interreg Atlantic Area Programme (EAPA_791/2018). Abraham Martin acknowledges funding from the Spanish Ministry of Education and Science (RYC-2017-22412, PID2019-107989RB-I00), the Basque Government (BIO18/IC/006), and Fundacio La Marato de TV3 (17/C/2017). Estibaliz Capetillo-Zarate acknowledges funding from the Basque Government (IT120319; ELKARTEK KK-2020/00034) and CIBERNED (CB06/0005/0076). The work was performed under the Maria de Maeztu Units of Excellence Programme -Grant MDM-2017-0720 funded by MCIN/AEI/10.13039/50110001103

Radiochemical examination of transthyretin (TTR) brain penetration assisted by iododiflunisal, a TTR tetramer stabilizer and a new candidate drug for AD

It is well settled that the amyloidogenic properties of the plasma protein transporter transthyretin (TTR) can be modulated by compounds that stabilize its native tetrameric conformation. TTR is also present in cerebrospinal fluid where it can bind to Aβ-peptides and prevent Aβ aggregation. We have previously shown that treatment of Alzheimer’s Disease (AD) model mice with iododiflunisal (IDIF), a TTR tetramer stabilizing compound, prevents AD pathologies. This evidence positioned IDIF as a new lead drug for AD. In dissecting the mechanism of action of IDIF, we disclose here different labeling strategies for the preparation of 131I-labeled IDIF and 131I- and 124I-labeled TTR, which have been further used for the preparation of IDIF-TTR complexes labeled either on the compound or the protein. The biodistribution of all labeled species after intravenous administration has been investigated in mice using ex vivo and in vivo techniques. Our results confirm the capacity of TTR to cross the blood brain barrier (BBB) and suggest that the formation of TTR-IDIF complexes enhances BBB permeability of both IDIF and TTR. The increased TTR and IDIF brain concentrations may result in higher Aβ-peptide sequestration capacity with the subsequent inhibition of AD symptoms as we have previously observed in mice. © 2019, The Author(s).The work was supported by a grant from the Fundació Marató de TV3 (Neurodegenerative Diseases Call, Project Reference 20140330-31-32-33-34, http://www.ccma.cat/tv3/marato/en/ projectes-financats/2013/212/). The group at CIC biomaGUNE also acknowledges MINECO (Spain) for funding through Grant CTQ2017-87637-R. I. Cardoso worked under the Investigator FCT Program which is financed by national funds through the Foundation for Science and Technology (FCT, Portugal) and co-financed by the European Social Fund (ESF) through the Human Potential Operational Programme (HPOP), type 4.2 - Promotion of Scientific Employment.Peer reviewe

Iodine Atoms: A New Molecular Feature for the Design of Potent Transthyretin Fibrillogenesis Inhibitors

The thyroid hormone and retinol transporter protein known as transthyretin (TTR) is in the origin of one of the 20 or so known amyloid diseases. TTR self assembles as a homotetramer leaving a central hydrophobic channel with two symmetrical binding sites. The aggregation pathway of TTR into amiloid fibrils is not yet well characterized but in vitro binding of thyroid hormones and other small organic molecules to TTR binding channel results in tetramer stabilization which prevents amyloid formation in an extent which is proportional to the binding constant. Up to now, TTR aggregation inhibitors have been designed looking at various structural features of this binding channel others than its ability to host iodine atoms. In the present work, greatly improved inhibitors have been designed and tested by taking into account that thyroid hormones are unique in human biochemistry owing to the presence of multiple iodine atoms in their molecules which are probed to interact with specific halogen binding domains sitting at the TTR binding channel. The new TTR fibrillogenesis inhibitors are based on the diflunisal core structure because diflunisal is a registered salicylate drug with NSAID activity now undergoing clinical trials for TTR amyloid diseases. Biochemical and biophysical evidence confirms that iodine atoms can be an important design feature in the search for candidate drugs for TTR related amyloidosis

Les molècules que modulen el dolor. Analgèsia i drogodependència, vint-i-cinc anys després del descobriment de les encefalines

7 pages, 8 figures.[CAT] La sensació de dolor és una de les experiències comunes a tot ésser humà. Entre els estímuls dolorosos, n’hi ha que estan adreçats a mantenir la integritat del cos advertint la presència d’agressions externes, però és sovint desitjable poder-los controlar, especialment quan són de naturalesa crònica. S’ha demostrat que el control del dolor no és una tasca fàcil, perquè, malgrat el gran esforç investigador fet en els darrers cent anys per tal de trobar noves substàncies analgèsiques, el millor remei continua essent avui la morfina. Tanmateix les expectatives derivades del descobriment dels opiacis endògens, les encefalines, no han conduït tampoc al desenvolupament d’un analgèsic ideal lliure de problemes greus com la tolerància i l’addicció.[ENG] The sensation of pain is a common human experience. Although pain stimuli also serve as a warning system against external body aggressions, it is always desirable to control them, especially when they are chronic. During the past century, a great deal of effort was devoted to finding new substances to alleviate pain. However, this proved to be a difficult task and, to date, morphine, is the best remedy. Moreover, the expectations raised from the discovery of the endogenous opioids, the enkephalins, have not been fulfilled and the ideal analgesic lacking tolerance and addictive effects is still eagerly awaited.Peer reviewe

Preparative Scale Production of Recombinant Human Transthyretin for Biophysical Studies of Protein-Ligand and Protein-Protein Interactions

© 2020 by the authors.Human transthyretin (hTTR), a serum protein with a main role in transporting thyroid hormones and retinol through binding to the retinol-binding protein, is an amyloidogenic protein involved in familial amyloidotic polyneuropathy (FAP), familial amyloidotic cardiomyopathy, and central nervous system selective amyloidosis. hTTR also has a neuroprotective role in Alzheimer disease, being the major Aβ binding protein in human cerebrospinal fluid (CSF) that prevents amyloid-β (Aβ) aggregation with consequent abrogation of toxicity. Here we report an optimized preparative expression and purification protocol of hTTR (wt and amyloidogenic mutants) for in vitro screening assays of TTR ligands acting as amyloidogenesis inhibitors or acting as molecular chaperones to enhance the TTR:Aβ interaction. Preparative yields were up to 660 mg of homogenous protein per L of culture in fed-batch bioreactor. The recombinant wt protein is mainly unmodified at Cys10, the single cysteine in the protein sequence, whereas the highly amyloidogenic Y78F variant renders mainly the S-glutathionated form, which has essentially the same amyloidogenic behavior than the reduced protein with free Cys10. The TTR production protocol has shown inter-batch reproducibility of expression and protein quality for in vitro screening assays.Work supported in part by grant PID2019-104350RB-I00 from MINECO and grant 2017SGR-727 from the Generalitat de Catalunya (to A.P.). G.A. acknowledges a grant from Fundació Marató de TV3, Spain (Project ref. 20140330-31-32-33-34). E.Y.C. acknowledges a contract funded by the project of Fundació Marató de TV3 and a contract from Ford España—Fundación Apadrina la Ciencia.Peer reviewe

Regioselective postsynthetic modification of phenylalanine side chains of peptides leading to uncommon ortho-iodinated analogues

5 pages, 4 schemes, 3 tables.-- Availcable online Dec 29, 2003.-- Supporting information available at: http://www.wiley-vch.de/contents/jc_2002/2004/z52464_s.pdfThis research was partially supportedby the Spanish MCYT (Grant BQU2001-3853) andthe FundaciGn la Caixa (Project Reference 00/ 010-00 of the IV Program of Grants for Research on Neurodegenarative Diseases of the FundaciGn La Caixa).Peer reviewe

Binding profile of the endogenous novel heptapeptide Met-enkephalin-Gly-tyr in zebrafish and rat brain

6 pages, 3 figures, 2 tables.-- PMID: 15901806 [PubMed].-- Printed version published Aug 2005.Zebrafish is considered a model organism, not only for the study of the biological functions of vertebrates but also as a tool to analyze the effects of some drugs or toxic agents. Five opioid precursor genes homologous to the mammalian opioid propeptide genes have recently been identified; one of these, the zebrafish proenkephalin, codes a novel heptapeptide, the Met-enkephalin-Gly-Tyr (MEGY). To analyze the pharmacological properties of this novel ligand, we have labeled it with tritium ([3H]MEGY). In addition, we have also synthesized two analogs: (D-Ala2)-MEGY (Y-D-Ala-GFMGY) and (D-Ala2, Val5)-MEGY (Y-D-Ala-GFVGY). The binding profile of these three agents has been studied in zebrafish and rat brain membranes. [3H]MEGY presents one binding site in zebrafish, as well as in rat brain membranes, although it shows a slight higher affinity in zebrafish brain. The observed saturable binding is displaced by naloxone, thus confirming the opioid nature of the binding sites. Competition binding assays indicate that the methionine residue is essential for high-affinity binding of MEGY and probably of other peptidic agonists in zebrafish, whereas the change of a Gly for a D-Ala does not dramatically affect the ligand affinity. Our results show that the percentage of [3H]MEGY displaced by all the ligands studied is higher than 100%, thus inferring that naloxone (used to determine nonspecific binding) does not bind to all the sites labeled by [3H]MEGY. Therefore, we can deduct that some of the MEGY binding sites should not be considered classical opioid sites.This study was supported by Ministerio de Educación y Ciencia (SAF2004-05144), Junta de Castilla y León (SA031/03/00B), and Hungarian National Scientific Research Foundation (Hungary) Grant T046514Peer reviewe