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1.
Proc Natl Acad Sci U S A ; 118(10)2021 03 09.
Artigo em Inglês | MEDLINE | ID: mdl-33658363

RESUMO

Blood pH is tightly maintained between 7.35 and 7.45, and acidosis (pH <7.3) indicates poor prognosis in sepsis, wherein lactic acid from anoxic tissues overwhelms the buffering capacity of blood. Poor sepsis prognosis is also associated with low zinc levels and the release of High mobility group box 1 (HMGB1) from activated and/or necrotic cells. HMGB1 added to whole blood at physiological pH did not bind leukocyte receptors, but lowering pH with lactic acid to mimic sepsis conditions allowed binding, implying the presence of natural inhibitor(s) preventing binding at normal pH. Testing micromolar concentrations of divalent cations showed that zinc supported the robust binding of sialylated glycoproteins with HMGB1. Further characterizing HMGB1 as a sialic acid-binding lectin, we found that optimal binding takes place at normal blood pH and is markedly reduced when pH is adjusted with lactic acid to levels found in sepsis. Glycan array studies confirmed the binding of HMGB1 to sialylated glycan sequences typically found on plasma glycoproteins, with binding again being dependent on zinc and normal blood pH. Thus, HMGB1-mediated hyperactivation of innate immunity in sepsis requires acidosis, and micromolar zinc concentrations are protective. We suggest that the potent inflammatory effects of HMGB1 are kept in check via sequestration by plasma sialoglycoproteins at physiological pH and triggered when pH and zinc levels fall in late stages of sepsis. Current clinical trials independently studying zinc supplementation, HMGB1 inhibition, or pH normalization may be more successful if these approaches are combined and perhaps supplemented by infusions of heavily sialylated molecules.


Assuntos
Acidose/sangue , Proteína HMGB1/sangue , Sepse/sangue , Sialoglicoproteínas/sangue , Zinco/sangue , Acidose/imunologia , Acidose/metabolismo , Acidose/patologia , Proteínas de Transporte , Proteína HMGB1/farmacologia , Humanos , Concentração de Íons de Hidrogênio , Imunidade Inata , Lipopolissacarídeos/farmacologia , Polissacarídeos/química , Sepse/imunologia , Sepse/patologia , Ácidos Siálicos/química , Sialoglicoproteínas/química , Zinco/metabolismo
2.
AAPS PharmSciTech ; 22(1): 16, 2021 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-33389218

RESUMO

Many anti-inflammatory therapies targeting neutrophils have been developed so far. A sialic acid (SA)-modified liposomal (SAL) formulation, based on the high expression of L-selectin in peripheral blood neutrophils (PBNs) and SA as its targeting ligand, has proved to be an effective neutrophil-mediated drug delivery system targeting rheumatoid arthritis (RA). The objective of this study was to investigate the influence of particle size of drug-carrying SALs transported and delivered by neutrophils on their anti-RA effect. Dexamethasone palmitate-loaded SALs (DP-SALs) of different particle sizes (300.2 ± 5.5 nm, 150.3 ± 4.3 nm, and 75.0 ± 3.9 nm) were prepared with DP as a model drug. Our study indicated that DP-SALs could efficiently target PBNs, with larger liposomes leading to higher drug accumulation in cells. However, a high intake of large DP-SALs by PBNs inhibited their migration ability and capacity to release the payload at the target site. In contrast, small DP-SALs (75.0 ± 3.9 nm) could maintain the drug delivery potential of PBNs, leading to their efficient accumulation at the inflammatory site, where PBNs would be excessively activated to form neutrophil extracellular traps along with efficient payload release (small DP-SALs) and finally to induce excellent anti-RA effect.


Assuntos
Anti-Inflamatórios/administração & dosagem , Artrite Reumatoide/tratamento farmacológico , Dexametasona/administração & dosagem , Lipossomos/química , Neutrófilos/efeitos dos fármacos , Ácidos Siálicos/química , Animais , Anti-Inflamatórios/uso terapêutico , Dexametasona/uso terapêutico , Sistemas de Liberação de Medicamentos , Humanos , Masculino , Ácido N-Acetilneuramínico/metabolismo , Ácido N-Acetilneuramínico/farmacologia , Ácido N-Acetilneuramínico/uso terapêutico , Tamanho da Partícula , Ratos , Ratos Wistar
3.
Int J Mol Sci ; 21(12)2020 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-32604730

RESUMO

The recently emerged SARS-CoV-2 is the cause of the global health crisis of the coronavirus disease 2019 (COVID-19) pandemic. No evidence is yet available for CoV infection into hosts upon zoonotic disease outbreak, although the CoV epidemy resembles influenza viruses, which use sialic acid (SA). Currently, information on SARS-CoV-2 and its receptors is limited. O-acetylated SAs interact with the lectin-like spike glycoprotein of SARS CoV-2 for the initial attachment of viruses to enter into the host cells. SARS-CoV-2 hemagglutinin-esterase (HE) acts as the classical glycan-binding lectin and receptor-degrading enzyme. Most ß-CoVs recognize 9-O-acetyl-SAs but switched to recognizing the 4-O-acetyl-SA form during evolution of CoVs. Type I HE is specific for the 9-O-Ac-SAs and type II HE is specific for 4-O-Ac-SAs. The SA-binding shift proceeds through quasi-synchronous adaptations of the SA-recognition sites of the lectin and esterase domains. The molecular switching of HE acquisition of 4-O-acetyl binding from 9-O-acetyl SA binding is caused by protein-carbohydrate interaction (PCI) or lectin-carbohydrate interaction (LCI). The HE gene was transmitted to a ß-CoV lineage A progenitor by horizontal gene transfer from a 9-O-Ac-SA-specific HEF, as in influenza virus C/D. HE acquisition, and expansion takes place by cross-species transmission over HE evolution. This reflects viral evolutionary adaptation to host SA-containing glycans. Therefore, CoV HE receptor switching precedes virus evolution driven by the SA-glycan diversity of the hosts. The PCI or LCI stereochemistry potentiates the SA-ligand switch by a simple conformational shift of the lectin and esterase domains. Therefore, examination of new emerging viruses can lead to better understanding of virus evolution toward transitional host tropism. A clear example of HE gene transfer is found in the BCoV HE, which prefers 7,9-di-O-Ac-SAs, which is also known to be a target of the bovine torovirus HE. A more exciting case of such a switching event occurs in the murine CoVs, with the example of the ß-CoV lineage A type binding with two different subtypes of the typical 9-O-Ac-SA (type I) and the exclusive 4-O-Ac-SA (type II) attachment factors. The protein structure data for type II HE also imply the virus switching to binding 4-O acetyl SA from 9-O acetyl SA. Principles of the protein-glycan interaction and PCI stereochemistry potentiate the SA-ligand switch via simple conformational shifts of the lectin and esterase domains. Thus, our understanding of natural adaptation can be specified to how carbohydrate/glycan-recognizing proteins/molecules contribute to virus evolution toward host tropism. Under the current circumstances where reliable antiviral therapeutics or vaccination tools are lacking, several trials are underway to examine viral agents. As expected, structural and non-structural proteins of SARS-CoV-2 are currently being targeted for viral therapeutic designation and development. However, the modern global society needs SARS-CoV-2 preventive and therapeutic drugs for infected patients. In this review, the structure and sialobiology of SARS-CoV-2 are discussed in order to encourage and activate public research on glycan-specific interaction-based drug creation in the near future.


Assuntos
Betacoronavirus/metabolismo , Infecções por Coronavirus/virologia , Evolução Molecular , Interações entre Hospedeiro e Microrganismos/fisiologia , Pneumonia Viral/virologia , Receptores Virais/metabolismo , Internalização do Vírus , Acetilesterase/metabolismo , Animais , Betacoronavirus/genética , Sítios de Ligação , Linhagem Celular , Coronavirus/genética , Esterases , Transferência Genética Horizontal , Glicosaminoglicanos/metabolismo , Hemaglutininas Virais/genética , Humanos , Lectinas/metabolismo , Pandemias , Polissacarídeos , Receptores Virais/química , Ácidos Siálicos/química , Ácidos Siálicos/metabolismo , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/fisiologia , Torovirus , Proteínas Virais de Fusão/genética
4.
Sci Rep ; 10(1): 7697, 2020 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-32376914

RESUMO

The alpha-2,8-linked form of the polysaccharide polysialic acid (PSA) has widespread implications in physiological and pathological processes, ranging from neurological development to disease progression. Though the high electronegativity and excluded volume of PSA often promotes interference of biomolecular interactions, PSA-binding ligands have important implications for both biological processes and biotechnological applications. As such, the design, identification, and characterisation of novel ligands towards PSA is critical for expanding knowledge of PSA interactions and achieving selective glycan targeting. Here, we report on a rational approach for the identification of alpha-2,8-PSA-binding peptides, involving design from the endogenous ligand Siglec-11 and multi-platform characterisation of peptide binding. Microarray-based examination of peptides revealed charge and sequence characteristics influencing peptide affinity to PSA, and carbohydrate-peptide binding was further quantified with a novel fluorescence anisotropy assay. PSA-binding peptides exhibited specific binding to polymeric SA, as well as different degrees of selective binding in various conditions, including competition with PSA of alternating 2,8/9-linkages and screening with PSA-expressing cells. A computational study of Siglec-11 and Siglec-11-derived peptides offered synergistic insight into ligand binding. These results demonstrate the potential of PSA-binding peptides for selective targeting and highlight the importance of the approaches described herein for the study of carbohydrate interactions.


Assuntos
Ligantes , Peptídeos/química , Ligação Proteica , Ácidos Siálicos/química , Sequência de Aminoácidos , Sítios de Ligação , Humanos , Biblioteca de Peptídeos
5.
J Med Chem ; 63(11): 6134-6143, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32406685

RESUMO

Native insulin is susceptible to biophysical aggregation and fibril formation, promoted by manual agitation and elevated temperatures. The safety of the drug and its application to alternative forms of administration could be enhanced through the identification of chemical modifications that strengthen its physical stability without compromising its biological properties. Complex polysialic acids (PSAs) exist naturally and provide a means to enhance the physical properties of peptide therapeutics. A set of insulin analogues site-specifically derivatized with sialic acid were prepared in an overall yield of 50-60%. Addition of a single or multiple sialic acids conferred remarkable enhancement to the biophysical stability of human insulin while maintaining its potency. The time to the onset of fibrillation was extended by more than 10-fold relative to that of the native hormone. These results demonstrate that simplified sialic acid conjugates represent a viable alternative to complex natural PSAs in increasing the stability of therapeutic peptides.


Assuntos
Insulina/análogos & derivados , Ácido N-Acetilneuramínico/química , Animais , Glicemia/análise , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Células HEK293 , Humanos , Insulina/farmacocinética , Insulina/uso terapêutico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Oligopeptídeos/síntese química , Oligopeptídeos/química , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Ácidos Siálicos/química , Equivalência Terapêutica
6.
Z Naturforsch C J Biosci ; 75(1-2): 41-49, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-32031984

RESUMO

The overexpression of sialic acids and sialyltransferases (STs) during malignant transformation and progression could result in the aberrant sialylation of cancer cells. Therefore, interfering the sialic acid synthesis might be an effective pathway in cancer therapy. In this study, we assessed that the antitumor inhibitors of 20(S)-ginsenosides Rg3, 20(R)-ginsenosides Rg3, 20(S)-ginsenosides Rh2, and 20(R)-ginsenosides Rh2 could block the sialoglycans in liver cancer cells HepG2. The results showed that these four compounds could inhibit the expressions of the total and free sialic acid at different levels in HepG2, respectively; also, it showed dose dependence. In addition, the results of the enzyme-linked immunosorbent assay showed that the above four compounds can inhibit the expression of STs significantly. We also found that these compounds could mediate the block of sialylation of α2,3- and α2,6-linked sialic acids in HepG2 cells by flow cytometry. Meanwhile, the results of the molecular docking investigation showed that these compounds showed strong interaction with ST6GalI and ST3GalI. These results verified that the ginsenosides have a powerful inhibiting aberrant sialylation, and it laid a theoretical foundation for further research on the investigation of ginsenosides as the target inhibitors on STs.


Assuntos
Ginsenosídeos/farmacologia , Ácidos Siálicos/química , Sialiltransferases/antagonistas & inibidores , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Ginsenosídeos/química , Células Hep G2 , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/patologia , Simulação de Acoplamento Molecular , Sialiltransferases/química
7.
Biochim Biophys Acta Mol Basis Dis ; 1866(5): 165692, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-31972227

RESUMO

Many important pathogen-host interactions rely on highly specific carbohydrate binding events. In the case of the protozoan Trypanosoma cruzi, the causative agent of Chagas disease, glycointeractions involving sialic acid (SA) residues are pivotal for parasite infectivity, escape from immune surveillance and pathogenesis. Though unable to synthesize SA de novo, T. cruzi displays a unique trans-Sialidase (TS) enzyme, which is able to cleave terminal SA residues from host donor glycoconjugates and transfer them onto parasite surface mucins, thus generating protective/adhesive structures. In addition, this parasite sheds TS into the bloodstream, as a way of modifying the surface SA signature, and thereby the signaling/functional properties of mammalian host target cells on its own advantage. Here, we discuss the pathogenic aspects of T. cruzi TS: its molecular adaptations, the multiplicity of interactions in which it is involved during infections, and the array of novel and appealing targets for intervention in Chagas disease provided by TS-remodeled sialoglycophenotypes.


Assuntos
Doença de Chagas/imunologia , Glicoproteínas/metabolismo , Interações Hospedeiro-Parasita/imunologia , Neuraminidase/metabolismo , Polissacarídeos/imunologia , Proteínas de Protozoários/metabolismo , Trypanosoma cruzi/patogenicidade , Animais , Doença de Chagas/parasitologia , Glicoproteínas/imunologia , Humanos , Evasão da Resposta Imune , Neuraminidase/imunologia , Polissacarídeos/química , Polissacarídeos/metabolismo , Proteínas de Protozoários/imunologia , Ácidos Siálicos/química , Ácidos Siálicos/imunologia , Ácidos Siálicos/metabolismo , Trypanosoma cruzi/enzimologia , Trypanosoma cruzi/imunologia , Fatores de Virulência/imunologia , Fatores de Virulência/metabolismo
8.
Haemophilia ; 26(1): 47-55, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31778283

RESUMO

INTRODUCTION: SHP656 is the first factor VIII (FVIII) product developed using polysialylation (PSA) technology, in which full-length recombinant (r) FVIII (anti-haemophilic factor [recombinant]) is conjugated with a 20 kDa PSA polymer. AIM: To compare the safety, immunogenicity and pharmacokinetics of SHP656 vs the parent rFVIII (octocog alfa) after single infusions of 25-75 IU/kg in patients with severe haemophilia A (FVIII activity <1%). METHODS: Multinational, phase 1, prospective, open-label, two-period, fixed-sequence, dose-escalation trial (clinicaltrials.gov NCT02716194). Patients received single doses of rFVIII and then SHP656 sequentially at the same dose: 25 ± 3 IU/kg (Cohort 1), 50 ± 5 IU/kg (Cohort 2) and 75 ± 5 IU/kg (Cohort 3). RESULTS: Forty patients received rFVIII: 11 in Cohort 1, 16 in Cohort 2 and 13 in Cohort 3. Two patients withdrew before receiving SHP656, leaving 38 patients who completed the study and received both treatments. No treatment-related adverse events (AEs), serious AEs, deaths, study withdrawals, thrombotic events or allergic reactions were reported; and no significant treatment-related changes in laboratory parameters or vital signs. No patients developed FVIII inhibitors or antibodies to PSA. FVIII activity was significantly prolonged following SHP656 administration vs rFVIII with an approximately 1.5-fold extension in mean residence time (P < .05). Exposure increased proportional to the SHP656 dose over the 25-75 IU/kg dose range. CONCLUSION: Polysialylation of rFVIII confers a half-life extension similar to that of approved extended half-life products that use either PEGylation or Fc fusion technology and was not associated with any treatment-related adverse events.


Assuntos
Fator VIII/farmacocinética , Fator VIII/uso terapêutico , Hemofilia A/tratamento farmacológico , Proteínas Recombinantes/uso terapêutico , Ácidos Siálicos/química , Adulto , Fator VIII/efeitos adversos , Fator VIII/imunologia , Humanos
9.
Nat Struct Mol Biol ; 26(12): 1151-1157, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31792450

RESUMO

The Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe and often lethal respiratory illness in humans, and no vaccines or specific treatments are available. Infections are initiated via binding of the MERS-CoV spike (S) glycoprotein to sialosides and dipeptidyl-peptidase 4 (the attachment and entry receptors, respectively). To understand MERS-CoV engagement of sialylated receptors, we determined the cryo-EM structures of S in complex with 5-N-acetyl neuraminic acid, 5-N-glycolyl neuraminic acid, sialyl-LewisX, α2,3-sialyl-N-acetyl-lactosamine and α2,6-sialyl-N-acetyl-lactosamine at 2.7-3.0 Å resolution. We show that recognition occurs via a conserved groove that is essential for MERS-CoV S-mediated attachment to sialosides and entry into human airway epithelial cells. Our data illuminate MERS-CoV S sialoside specificity and suggest that selectivity for α2,3-linked over α2,6-linked receptors results from enhanced interactions with the former class of oligosaccharides. This study provides a structural framework explaining MERS-CoV attachment to sialoside receptors and identifies a site of potential vulnerability to inhibitors of viral entry.


Assuntos
Coronavírus da Síndrome Respiratória do Oriente Médio/química , Ácidos Siálicos/metabolismo , Glicoproteína da Espícula de Coronavírus/química , Sítios de Ligação , Configuração de Carboidratos , Microscopia Crioeletrônica , Dipeptidil Peptidase 4/química , Dipeptidil Peptidase 4/metabolismo , Dipeptidil Peptidase 4/ultraestrutura , Hemaglutinação por Vírus , Humanos , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Domínios Proteicos , Mapeamento de Interação de Proteínas , Ácidos Siálicos/química , Glicoproteína da Espícula de Coronavírus/metabolismo , Glicoproteína da Espícula de Coronavírus/ultraestrutura , Relação Estrutura-Atividade
10.
Front Immunol ; 10: 2478, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31781090

RESUMO

In order to combat invading pathogens neutrophils can release neutrophil extracellular traps (NETs). However, since NETs can also damage endogenous cells, several control mechanisms for the formation of NETs must work effectively. For instance, neutrophil activation is silenced within blood circulation by the binding of sialylated glycoconjugates to sialic acid binding immunoglobulin-like lectins (Siglecs) on neutrophils. As neutrophils are recruited within the female reproductive tract, after mating, a comparable mechanism may also take place within the bovine cervix to prevent an exaggerated NET formation and thus, infertility. We examined, if the highly glycosylated mucins, which are the major functional fraction of biomolecules in mucus, represent a potential regulator of NET formation. The qPCR data revealed that in polymorphonuclear neutrophils (PMNs) inhibitory Siglecs are the most frequently expressed Siglecs and might be a potential target of sialylated glycans to modulate the activation of PMNs. Remarkably, the addition of bovine cervical mucins significantly inhibited the formation of NET, which had been induced in response to lipopolysaccharides (LPS) or a combination of phorbol myristate acetate (PMA) and ionomycin. The inhibitory effects were independent of the stage of estrous cycle (estrus, luteal, and follicular mucins). PMNs retained their segmented nuclei and membrane perforation was prevented. However, the inhibitory effects were diminished, when sialic acids were released under acidic conditions. Comparable results were achieved, when sialic acids were targeted by neuraminidase digestion, indicating a sialic acid dependent inhibition of NET release. Thus, bovine cervical mucins have an anti-inflammatory capability to modulate NET formation and might be further immunomodulatory biomolecules that support fertility.


Assuntos
Colo do Útero/metabolismo , Armadilhas Extracelulares/metabolismo , Mucinas/metabolismo , Ativação de Neutrófilo , Neutrófilos/metabolismo , Sequência de Aminoácidos , Animais , Bovinos , Colo do Útero/imunologia , Armadilhas Extracelulares/imunologia , Feminino , Expressão Gênica , Glicosilação , Hidrólise , Imuno-Histoquímica , Modelos Moleculares , Ativação de Neutrófilo/imunologia , Neutrófilos/imunologia , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico/química , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico/genética , Lectinas Semelhantes a Imunoglobulina de Ligação ao Ácido Siálico/metabolismo , Ácidos Siálicos/química , Ácidos Siálicos/metabolismo , Relação Estrutura-Atividade
11.
Proc Jpn Acad Ser B Phys Biol Sci ; 95(9): 523-537, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31708496

RESUMO

Mass spectrometry (MS) is a well-accepted means for analyzing glycans. Before glycan analysis by MS, several chemical derivatizations are generally carried out. These are classified into three categories; (1) labeling of the reducing end of glycans, (2) permethylation, and (3) sialic acid derivatization. Because sialic acid residues are unstable, they are easily lost during pretreatment and during or after ionization in a mass spectrometer. Sialic acid derivatization can prevent the loss of this residue. Recently, new types of sialic acid derivatization techniques have been developed, which allow straight-forward sialic acid linkage analysis (α2,3-/α2,6-linkages) as well as residue stabilization. This review summarizes the developments in sialic acid derivatization techniques, especially the varied methods of sialic acid linkage-specific derivatization.


Assuntos
Espectrometria de Massas , Polissacarídeos/análise , Ácidos Siálicos/química , Animais , Glicopeptídeos/química , Humanos , Lactonas/química , Espectrometria de Massas/métodos , Estrutura Molecular , Oxirredução
12.
Nat Commun ; 10(1): 5404, 2019 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-31776339

RESUMO

Glycosylation plays important roles in cellular function and endows protein therapeutics with beneficial properties. However, constructing biosynthetic pathways to study and engineer precise glycan structures on proteins remains a bottleneck. Here, we report a modular, versatile cell-free platform for glycosylation pathway assembly by rapid in vitro mixing and expression (GlycoPRIME). In GlycoPRIME, glycosylation pathways are assembled by mixing-and-matching cell-free synthesized glycosyltransferases that can elaborate a glucose primer installed onto protein targets by an N-glycosyltransferase. We demonstrate GlycoPRIME by constructing 37 putative protein glycosylation pathways, creating 23 unique glycan motifs, 18 of which have not yet been synthesized on proteins. We use selected pathways to synthesize a protein vaccine candidate with an α-galactose adjuvant motif in a one-pot cell-free system and human antibody constant regions with minimal sialic acid motifs in glycoengineered Escherichia coli. We anticipate that these methods and pathways will facilitate glycoscience and make possible new glycoengineering applications.


Assuntos
Sistema Livre de Células/metabolismo , Engenharia de Proteínas/métodos , Proteínas/metabolismo , Antígenos CD/metabolismo , Escherichia coli/genética , Glicoproteínas/biossíntese , Glicosilação , Glicosiltransferases/genética , Glicosiltransferases/metabolismo , Humanos , Redes e Vias Metabólicas , Oligossacarídeos/metabolismo , Polissacarídeos/metabolismo , Proteínas/genética , Ácidos Siálicos/química , Ácidos Siálicos/metabolismo , Sialiltransferases/metabolismo
13.
J Org Chem ; 84(23): 15052-15062, 2019 12 06.
Artigo em Inglês | MEDLINE | ID: mdl-31718181

RESUMO

A novel 8-O-picoloylated sialyl donor has been developed, and the performance of various picoloylated sialyl donors in glycosylations with primary glycosyl acceptors has been evaluated. 8-O-Picoloyl and 4,9-di-O-picoloyl sialyl donors produced moderate to excellent yields of disaccharides with complete α-stereoselectivities. Synergistic effects between picoloyl and the accompanying O-protecting groups (benzoyl vs acetyl) were evaluated, as well as the effects of triflic acid concentration on the 8-O-picoloyl donor. 1H NMR analysis was also carried out to assess differences in the hydrogen-bonding net between sialyl donors.


Assuntos
Dissacarídeos/síntese química , Ácidos Siálicos/química , Configuração de Carboidratos , Dissacarídeos/química , Glicosilação , Ligação de Hidrogênio , Estereoisomerismo
14.
Viruses ; 11(10)2019 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-31615155

RESUMO

Virus infections are initiated by the attachment of the viral particle to protein or carbohydrate receptors on the host cell. Sialic acid-bearing glycan structures are prominently displayed at the cell surface, and, consequently, these structures can function as receptors for a large number of diverse viruses. Structural biology research has helped to establish the molecular bases for many virus-sialic acid interactions. Due to the icosahedral 532 point group symmetry that underlies many viral capsids, the receptor binding sites are frequently arranged in a highly symmetric fashion and linked by five-fold, three-fold, or two-fold rotation axes. For the inhibition of viral attachment, one emerging strategy is based on developing multivalent sialic acid-based inhibitors that can simultaneously engage several of these binding sites, thus binding viral capsids with high avidity. In this review, we will evaluate the structures of non-enveloped virus capsid proteins bound to sialylated glycan receptors and discuss the potential of these structures for the development of potent antiviral attachment inhibitors.


Assuntos
Polissacarídeos/química , Ácidos Siálicos/química , Ligação Viral , Vírus/química , Antivirais/farmacologia , Sítios de Ligação , Cristalografia por Raios X , Modelos Moleculares , Receptores Virais , Vírus/efeitos dos fármacos
15.
Curr Top Med Chem ; 19(25): 2271-2282, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31648641

RESUMO

Polysialic acid (polySia) is a novel glycan that posttranslationally modifies neural cell adhesion molecules (NCAMs) in mammalian cells. Up-regulation of polySia-NCAM expression or NCAM polysialylation is associated with tumor cell migration and progression in many metastatic cancers and neurocognition. It has been known that two highly homologous mammalian polysialyltransferases (polySTs), ST8Sia II (STX) and ST8Sia IV (PST), can catalyze polysialylation of NCAM, and two polybasic domains, polybasic region (PBR) and polysialyltransferase domain (PSTD) in polySTs play key roles in affecting polyST activity or NCAM polysialylation. However, the molecular mechanisms of NCAM polysialylation and cell migration are still not entirely clear. In this minireview, the recent research results about the intermolecular interactions between the PBR and NCAM, the PSTD and cytidine monophosphate-sialic acid (CMP-Sia), the PSTD and polySia, and as well as the intramolecular interaction between the PBR and the PSTD within the polyST, are summarized. Based on these cooperative interactions, we have built a novel model of NCAM polysialylation and cell migration mechanisms, which may be helpful to design and develop new polysialyltransferase inhibitors.


Assuntos
Movimento Celular , Moléculas de Adesão de Célula Nervosa/metabolismo , Ácidos Siálicos/metabolismo , Animais , Humanos , Moléculas de Adesão de Célula Nervosa/química , Ácidos Siálicos/química
16.
Carbohydr Polym ; 224: 115145, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472857

RESUMO

Polysialic acid (polySia) is a unique, well-characterised carbohydrate polymer highly-expressed on the cell surface of neurons in the early stages of mammalian brain development. Post-embryogenesis, it is also re-expressed in a number of tumours of neuroendocrine origin. It plays important roles in modulating cell-cell, and cell-matrix adhesion and migration, tumour invasion and metastasis. Techniques for structural and quantitative characterisation of polySia from tumours and cancer cells are thus essential in exploring the relationship between polySia expression levels and structural and functional changes associated with cancer progression and metastasis. A variety of techniques have been developed to structurally and quantitatively analyse polySia in clinical tissues and other biological samples. In this review, analytical approaches used for the determination of polySia in biological matrices in the past 20 years are discussed, with a particular focus on chemical approaches, and quantitative analysis.


Assuntos
Testes de Química Clínica/métodos , Ácidos Siálicos/análise , Animais , Humanos , Ácidos Siálicos/química , Ácidos Siálicos/isolamento & purificação
17.
Artigo em Inglês | MEDLINE | ID: mdl-31476363

RESUMO

Understanding variation in physiological traits across taxa is a central question in evolutionary biology that has wide-ranging implications in biomedicine, disease ecology, and environmental protection. Sialic acid (Sia), and in particular, 5-N-acetylneuraminic acid (Neu5Ac), is chemically bound to galactose and the underlying glycan via α2-3 or α2-6 glycosidic linkage (i.e., Siaα2-3Galactose or Siaα2-6Galactose), conferring two different cell surface structures that affects cell to cell communication and interactions with foreign agents including microparasites and toxins. As an initial step towards understanding variation of Sia across the class Aves, we collected red blood cells (RBCs or erythrocytes) and measured Sia quantity in 76 species and 340 individuals using HPLC-MS/MS and glycosidic linkage type in 24 species and 105 individuals using hemagglutination assay. Although Sia quantity did not, α2-6 glycosidic linkage did exhibit a discernable phylogenetic pattern as evaluated by a phylogenetic signal (λ) value of 0.7. Sia quantity appeared to be higher in after hatch year birds than hatch year birds (P < 0.05); moreover, ~80% of the measured Sia across all individuals or species was expressed by ~20% of the individuals or species. Lastly, as expected, we detected a minimal presence of 5-N-glycolylneuraminic acid in the avian RBCs tested. These data provide novel insights and a large baseline dataset for further study on the variability of Sia in the class Aves which might be useful for understanding Sia dependent processes in birds.


Assuntos
Aves/metabolismo , Eritrócitos/metabolismo , Ácidos Siálicos/metabolismo , Animais , Aves/classificação , Eritrócitos/química , Ácidos Siálicos/química , Especificidade da Espécie
18.
Colloids Surf B Biointerfaces ; 183: 110413, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31401461

RESUMO

A novel bioinspired nanoplatform capable of fast endocytosis, lysosomal pH-triggered drug release, and reduced drug efflux based on PBA-PEG-b-P(Glu-co-GluDA) copolymer was developed in this study. The synthesized copolymer could facilitate doxorubicin encapsulation with relatively high drug-loading content and efficiency. Inspired by mussel byssal threads, a core crosslinking strategy based on the coordination between catechol and ferric ions was introduced to improve the stability of nanomicelles and realize lysosomal pH-controlled drug release. This nanoplatform could maintain integrity even after being dissolved in a good solvent, demonstrating its the potential to withstand infinite dilution of plasma after intravenous injection. Moreover, this nanoplatform demonstrated lysosomal pH-triggered drug release, and the cumulative release amount of doxorubicin under a simulated lysosomal condition was 13 times higher than that under a simulated plasma condition. Moreover, as a result of the high binding capacity between phenylboronic acid (PBA) and sialic acid on the surface of human hepatoma cell line (HepG2), the fast and enhanced endocytosis in addition to lysosomal pH-triggered release property and significantly low efflux, this nanoplatform exhibits improved delivery efficiency of doxorubicin into the nucleus and notably outstanding antiproliferative effects compared with doxorubicin. Furthermore, the PBA modification remarkably increased the mean fluorescence intensity of this nanoplatform endocytosed by HepG2 cells to twice that of doxorubicin after one hour of incubation. The nanoplatform exhibited an inhibition rate of 70% against tumor growth. Thus, this novel nanoplatform based on PBA-PEG-b-P(Glu-co-GluDA) copolymer displayed multifunctionality and exhibited great potential as an intelligent nanoplatform for antitumor drug delivery.


Assuntos
Antibióticos Antineoplásicos/farmacologia , Núcleo Celular/efeitos dos fármacos , Preparações de Ação Retardada , Doxorrubicina/farmacologia , Lisossomos/efeitos dos fármacos , Nanopartículas/química , Antibióticos Antineoplásicos/metabolismo , Materiais Biomiméticos/química , Ácidos Borônicos/química , Ácidos Borônicos/metabolismo , Catecóis/química , Catecóis/metabolismo , Núcleo Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Doxorrubicina/metabolismo , Composição de Medicamentos/métodos , Endocitose , Células Hep G2 , Humanos , Concentração de Íons de Hidrogênio , Ferro/química , Ferro/metabolismo , Lisossomos/metabolismo , Micelas , Nanopartículas/ultraestrutura , Polietilenoglicóis/química , Polietilenoglicóis/metabolismo , Ácidos Siálicos/química , Ácidos Siálicos/metabolismo
19.
Talanta ; 205: 120104, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31450448

RESUMO

Body fluid N-glycome analysis as well as glyco-proteoform profiling of existing protein biomarkers potentially provides a stratification layer additional to quantitative, diagnostic protein levels. For clinical omics applications, the collection of a dried blood spot (DBS) is increasingly pursued as an alternative to sampling milliliters of peripheral blood. Here we evaluate DBS cards as a blood collection strategy for protein N-glycosylation analysis aiming for high-throughput clinical applications. A protocol for facile N-glycosylation profiling from DBS is developed that includes sialic acid linkage differentiation. This protocol is based on a previously established total plasma N-glycome mass spectrometry (MS) method, with adjustments for the analysis of DBS specimens. After DBS-punching and protein solubilization N-glycans are released, followed by chemical derivatization of sialic acids and MS-measurement of N-glycan profiles. With this method, more than 80 different glycan structures are identified from a DBS, with RSDs below 10% for the ten most abundant glycans. N-glycan profiles of finger-tip blood and venous blood are compared and short-term stability of DBS is demonstrated. This method for fast N-glycosylation profiling of DBS provides a minimally invasive alternative to conventional serum and plasma protein N-glycosylation workflows. With simplified blood sampling this DBS approach has vast potential for clinical glycomics applications.


Assuntos
Teste em Amostras de Sangue Seco/métodos , Glicômica/métodos , Polissacarídeos/sangue , Humanos , Polissacarídeos/química , Ácidos Siálicos/química , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz/métodos
20.
J Am Chem Soc ; 141(36): 14032-14037, 2019 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-31460762

RESUMO

The Siglec family of cell surface receptors have emerged as attractive targets for cell-directed therapies due to their restricted expression on immune cells, endocytic properties, and ability to modulate receptor signaling. Human Siglec-8, for instance, has been identified as a therapeutic target for the treatment of eosinophil and mast cell disorders. A promising strategy to target Siglecs involves the use of liposomal nanoparticles with a multivalent display of Siglec ligands. A key challenge for this approach is the identification of a high affinity ligand for the target Siglec. Here, we report the development of a ligand of Siglec-8 and its closest murine functional orthologue Siglec-F that is capable of targeting liposomes to cells expressing Siglec-8 or -F. A glycan microarray library of synthetic 9-N-sulfonyl sialoside analogues was screened to identify potential lead compounds. The best ligand, 9-N-(2-naphthyl-sulfonyl)-Neu5Acα2-3-[6-O-sulfo]-Galß1-4GlcNAc (6'-O-sulfo NSANeu5Ac) combined the lead 2-naphthyl sulfonyl C-9 substituent with the preferred sulfated scaffold. The ligand 6'-O-sulfo NSANeu5Ac was conjugated to lipids for display on liposomes to evaluate targeted delivery to cells. Targeted liposomes showed strong in vitro binding/uptake and selectivity to cells expressing Siglec-8 or -F and, when administered to mice, exhibit in vivo targeting to Siglec-F+ eosinophils.


Assuntos
Antígenos de Diferenciação Mielomonocítica/metabolismo , Linfócitos B/efeitos dos fármacos , Lectinas/antagonistas & inibidores , Ácidos Siálicos/farmacologia , Sulfonamidas/farmacologia , Linfócitos T/efeitos dos fármacos , Animais , Antígenos CD/metabolismo , Antígenos de Diferenciação de Linfócitos B/metabolismo , Linfócitos B/metabolismo , Células CHO , Cricetulus , Humanos , Lectinas/metabolismo , Lipossomos/química , Lipossomos/metabolismo , Camundongos , Conformação Molecular , Ácidos Siálicos/química , Sulfonamidas/química , Linfócitos T/metabolismo
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