INTRODUCTION: Adrenergic activation of protein kinase A (PKA) in cardiac muscle targets the sarcolemma, sarcoplasmic reticulum, and contractile apparatus to increase contractile force and heart rate. In the thin filaments of the contractile apparatus, cardiac troponin I (cTnI) Ser22 and Ser23 in the cardiac-specific N-terminal peptide (NcTnI: residues 1 to 32) are the targets for PKA phosphorylation. Phosphorylation causes a 2-3 fold decrease of affinity of cTn for Ca2+ associated with a higher rate of Ca2+ dissociation from cTnC leading to a faster relaxation rate of the cardiac muscle (lusitropy). Cardiomyopathy-linked mutations primarily affect Ca2+ regulation or the PKA-dependent modulatory system, such that Ca2+-sensitivity becomes independent of phosphorylation level (uncoupling) and this could be sufficient to induce cardiomyopathy. A drug that could restore the phosphorylation-dependent modulation of Ca2+-sensitivity could have potential for treatment of these pathologies. We have found that a number of small molecules, including silybin B, resveratrol and EGCG, can restore coupling in single filament assays. METHODS: We did molecular dynamics simulations (5x1500ns for each condition) of the unphosphorylated and phosphorylated cardiac troponin core with the G159D DCM mutation in the presence of the 5 ligands and analysed the effects on several dynamic parameters. We also studied the effect of the ligands on the contractility of cardiac muscle myocytes with ACTC E99K and TNNT2 R92Q mutations in response to dobutamine. RESULTS: Silybin B, EGCG and resveratrol restored the phosphorylation-induced change in molecular dynamics to wild-type values, whilst silybin A, an inactive isomer of silybin B, and Epicatechin gallate, an EGCG analogue that does not recouple, did not. We analysed the atomic-level changes induced by ligand binding to explain recoupling. Mutations ACTC E99K and TNNT2 R92Q blunt the increased relaxation speed response to β1 adrenergic stimulation of cardiac myocytes and we found that resveratrol, EGCG and silybin B could restore the β1 adrenergic response, whereas silybin A did not. DISCUSSION: The uncoupling phenomenon caused by cardiomyopathy-related mutations and the ability of small molecules to restore coupling in vitro and lusitropy in myocytes is observed at the cellular, molecular and atomistic levels therefore, restoring lusitropy is a suitable target for treatment. Further research on compounds that restore lusitropy is thus indicated as treatments for genetic cardiomyopathies. Further molecular dynamics simulations could define the specific properties needed for recoupling and allow for the prediction and design of potential new drugs.
- Publikační typ
- časopisecké články MeSH
Pulmonary hypertension is a cardiovascular disease with a low survival rate. The protein galectin-3 (Gal-3) binding β-galactosides of cellular glycoproteins plays an important role in the onset and development of this disease. Carbohydrate-based drugs that target Gal-3 represent a new therapeutic strategy in the treatment of pulmonary hypertension. Here, we present the synthesis of novel hydrophilic glycopolymer inhibitors of Gal-3 based on a polyoxazoline chain decorated with carbohydrate ligands. Biolayer interferometry revealed a high binding affinity of these glycopolymers to Gal-3 in the subnanomolar range. In the cell cultures of cardiac fibroblasts and pulmonary artery smooth muscle cells, the most potent glycopolymer 18 (Lac-high) caused a decrease in the expression of markers of tissue remodeling in pulmonary hypertension. The glycopolymers were shown to penetrate into the cells. In a biodistribution and pharmacokinetics study in rats, the glycopolymers accumulated in heart and lung tissues, which are most affected by pulmonary hypertension.
- MeSH
- arteria pulmonalis účinky léků metabolismus MeSH
- biologické markery MeSH
- fibroblasty účinky léků metabolismus MeSH
- galektin 3 * antagonisté a inhibitory metabolismus MeSH
- krysa rodu rattus MeSH
- kultivované buňky MeSH
- lidé MeSH
- plicní hypertenze * farmakoterapie metabolismus MeSH
- polymery chemie farmakologie MeSH
- tkáňová distribuce MeSH
- zvířata MeSH
- Check Tag
- krysa rodu rattus MeSH
- lidé MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
A new class of compounds, namely highly substituted diaminocyclopentane-l-lysine adducts, have been discovered as potent inhibitors of O-GlcNAcase, an enzyme crucial for protein de-O-glycosylation. These inhibitors exhibit exceptional selectivity and reversibility and are the first example of human O-GlcNAcase inhibitors that are structurally related to the transition state of the rate-limiting step with the "aglycon" still in bond-length proximity. The ease of their preparation, remarkable biological activities, stability, and non-toxicity make them promising candidates for the development of anti-tau-phosphorylation agents holding significant potential for the treatment of Alzheimer's disease.
- MeSH
- beta-N-acetylhexosaminidasy antagonisté a inhibitory metabolismus MeSH
- cyklopentany chemie farmakologie chemická syntéza MeSH
- inhibitory enzymů * chemie farmakologie chemická syntéza MeSH
- lidé MeSH
- lysin * chemie farmakologie MeSH
- molekulární struktura MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
The binding of human galectins by glycomimetic inhibitors is a promising therapeutic approach. The structurally distinct group of tandem-repeat galectins has scarcely been studied so far, and there is hardly any knowledge on their ligand specificity or their inhibitory potential, particularly concerning non-natural carbohydrates. Here, we present the synthesis of a library of seven 3-O-disubstituted thiodigalactoside-derived glycomimetics and their affinity to two tandem-repeat galectins, Gal-8 and Gal-9. The straightforward synthesis of these glycomimetics involved dibutyltin oxide-catalyzed 3,3́-O-disubstitution of commercially available unprotected thiodigalactoside, and conjugation of various aryl substituents by copper-catalyzed Huisgen azide-alkyne cycloaddition (CuAAC). The inhibitory potential of the prepared glycomimetics for Gal-8 and Gal-9 was assessed, and compared with the established galectins Gal-1 and Gal-3. The introduction of C-3 substituents resulted in an over 40-fold increase in affinity compared with unmodified TDG. The structure-affinity relations within the studied series were discussed using molecular modeling. Furthermore, the prepared glycomimetics were shown to scavenge Gal-8 and Gal-9 from the surface of cancer cells. This pioneering study on the synthetic inhibitors especially of Gal-9 identified lead compounds that may be used in further biomedical research.
- MeSH
- galektiny * metabolismus MeSH
- lidé MeSH
- sacharidy chemie MeSH
- thiogalaktosidy * chemie MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Galectins are proteins of the family of human lectins. By binding terminal galactose units of cell surface glycans, they moderate biological and pathological processes such as cell signaling, cell adhesion, apoptosis, fibrosis, carcinogenesis, and metabolic disorders. The binding of monovalent glycans to galectins is usually relatively weak. Therefore, the presentation of carbohydrate ligands on multivalent scaffolds can efficiently increase and/or discriminate the affinity of the glycoconjugate to different galectins. A library of glycoclusters and glycodendrimers with various structural presentations of the common functionalized N-acetyllactosamine ligand was prepared to evaluate how the mode of presentation affects the affinity and selectivity to the two most abundant galectins, galectin-1 (Gal-1) and galectin-3 (Gal-3). In addition, the effect of a one- to two-unit carbohydrate spacer on the affinity of the glycoconjugates was determined. A new design of the biolayer interferometry (BLI) method with specific AVI-tagged constructs was used to determine the affinity to galectins, and compared with the gold-standard method of isothermal titration calorimetry (ITC). This study reveals new routes to low nanomolar glycoconjugate inhibitors of galectins of interest for biomedical research.
- MeSH
- galektiny * metabolismus MeSH
- glykokonjugáty * farmakologie chemie MeSH
- lidé MeSH
- ligandy MeSH
- polysacharidy metabolismus MeSH
- sacharidy chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Elevated levels of galectin-3 are associated with tumorigenesis. Its inhibition with high-affinity carbohydrate ligands opens new therapeutic routes. Targeting of intracellular galectin-3 is challenging for polar inhibitors like carbohydrates. We demonstrate the potential of novel biomedical research tools, glycocalix[4]arenes, to enter epithelial cells, which may allow their interaction with galectin-3.
- MeSH
- buněčná membrána MeSH
- galektin 3 * MeSH
- galektiny MeSH
- glykokalyx * MeSH
- sacharidy farmakologie MeSH
- Publikační typ
- časopisecké články MeSH
Galectins are carbohydrate-binding lectins that modulate the proliferation, apoptosis, adhesion, or migration of cells by cross-linking glycans on cell membranes or extracellular matrix components. Galectin-4 (Gal-4) is a tandem-repeat-type galectin expressed mainly in the epithelial cells of the gastrointestinal tract. It consists of an N- and a C-terminal carbohydrate-binding domain (CRD), each with distinct binding affinities, interconnected with a peptide linker. Compared to other more abundant galectins, the knowledge of the pathophysiology of Gal-4 is sparse. Its altered expression in tumor tissue is associated with, for example, colon, colorectal, and liver cancers, and it increases in tumor progression, and metastasis. There is also very limited information on the preferences of Gal-4 for its carbohydrate ligands, particularly with respect to Gal-4 subunits. Similarly, there is virtually no information on the interaction of Gal-4 with multivalent ligands. This work shows the expression and purification of Gal-4 and its subunits and presents a structure-affinity relationship study with a library of oligosaccharide ligands. Furthermore, the influence of multivalency is demonstrated in the interaction with a model lactosyl-decorated synthetic glycoconjugate. The present data may be used in biomedical research for the design of efficient ligands of Gal-4 with diagnostic or therapeutic potential.
Aging is a complex physiological process that can be accelerated by chemical (high blood glucose levels) or physical (solar exposure) factors. It is accompanied by the accumulation of altered molecules in the human body. The accumulation of oxidatively modified and glycated proteins is associated with inflammation and the progression of chronic diseases (aging). The use of antiglycating agents is one of the recent approaches in the preventive strategy of aging and natural compounds seem to be promising candidates. Our study focused on the anti-aging effect of the flavonoid hesperetin, its glycoside hesperidin and its carbohydrate moieties rutinose and rhamnose on young and physiologically aged normal human dermal fibroblasts (NHDFs). The anti-aging activity of the test compounds was evaluated by measuring matrix metalloproteinases (MMPs) and inflammatory interleukins by ELISA. The modulation of elastase, hyaluronidase, and collagenase activity by the tested substances was evaluated spectrophotometrically by tube tests. Rutinose and rhamnose inhibited the activity of pure elastase, hyaluronidase, and collagenase. Hesperidin and hesperetin inhibited elastase and hyaluronidase activity. In skin aging models, MMP-1 and MMP-2 levels were reduced after application of all tested substances. Collagen I production was increased after the application of rhamnose and rutinose.
- MeSH
- hesperidin * farmakologie MeSH
- hyaluronoglukosaminidasa MeSH
- kolagenasy metabolismus MeSH
- lidé MeSH
- pankreatická elastasa MeSH
- rhamnosa * farmakologie MeSH
- stárnutí kůže * účinky léků MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Galectins are lectins that bind β-galactosides. They are involved in important extra- and intracellular biological processes such as apoptosis, and regulation of the immune system or the cell cycle. High-affinity ligands of galectins may introduce new therapeutic approaches or become new tools for biomedical research. One way of increasing the low affinity of β-galactoside ligands to galectins is their multivalent presentation, e.g., using calixarenes. We report on the synthesis of glycocalix[4]arenes in cone, partial cone, 1,2-alternate, and 1,3-alternate conformations carrying a lactosyl ligand on three different linkers. The affinity of the prepared compounds to a library of human galectins was determined using competitive ELISA assay and biolayer interferometry. Structure-affinity relationships regarding the influence of the linker and the core structure were formulated. Substantial differences were found between various linker lengths and the position of the triazole unit. The formation of supramolecular clusters was detected by atomic force microscopy. The present work gives a systematic insight into prospective galectin ligands based on the calix[4]arene core.
- MeSH
- galektiny * chemie MeSH
- glykokalyx * MeSH
- lidé MeSH
- ligandy MeSH
- molekulární konformace MeSH
- prospektivní studie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
β-N-Acetylhexosaminidase from Talaromyces flavus (TfHex; EC 3.2.1.52) is an exo-glycosidase with dual activity for cleaving N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) units from carbohydrates. By targeting a mutation hotspot of the active site residue Glu332, we prepared a library of ten mutant variants with their substrate specificity significantly shifted towards GlcNAcase activity. Suitable mutations were identified by in silico methods. We optimized a microtiter plate screening method in the yeast Pichia pastoris expression system, which is required for the correct folding of tetrameric fungal β-N-acetylhexosaminidases. While the wild-type TfHex is promiscuous with its GalNAcase/GlcNAcase activity ratio of 1.2, the best single mutant variant Glu332His featured an 8-fold increase in selectivity toward GlcNAc compared with the wild-type. Several prepared variants, in particular Glu332Thr TfHex, had significantly stronger transglycosylation capabilities than the wild-type, affording longer chitooligomers - they behaved like transglycosidases. This study demonstrates the potential of mutagenesis to alter the substrate specificity of glycosidases.
