TY - JOUR AU - Pethő, Zoltán Dénes AU - Pajtás, Dávid AU - Piga, Martina AU - Magyar, Zsuzsanna Édua AU - Zákány, Florina AU - Kovács, Tamás AU - Zidar, Nace AU - Panyi, György AU - Varga, Zoltán AU - Papp, Ferenc TI - A synthetic flavonoid derivate in the plasma membrane transforms the voltage‐clamp fluorometry signal of CiHv1 JF - FEBS JOURNAL J2 - FEBS J PY - 2024 PG - 18 SN - 1742-464X DO - 10.1111/febs.17105 UR - https://m2.mtmt.hu/api/publication/34722791 ID - 34722791 N1 - Early View AB - Voltage‐clamp fluorometry (VCF) enables the study of voltage‐sensitive proteins through fluorescent labeling accompanied by ionic current measurements for voltage‐gated ion channels. The heterogeneity of the fluorescent signal represents a significant challenge in VCF. The VCF signal depends on where the cysteine mutation is incorporated, making it difficult to compare data among different mutations and different studies and standardize their interpretation. We have recently shown that the VCF signal originates from quenching amino acids in the vicinity of the attached fluorophores, together with the effect of the lipid microenvironment. Based on these, we performed experiments to test the hypothesis that the VCF signal could be altered by amphiphilic quenching molecules in the cell membrane. Here we show that a phenylalanine‐conjugated flavonoid (4‐oxo‐2‐phenyl‐4H‐chromene‐7‐yl)‐phenylalanine, (later Oxophench) has potent effects on the VCF signals of the Ciona intestinalis H V 1 (CiHv1) proton channel. Using spectrofluorimetry, we showed that Oxophench quenches TAMRA (5(6)‐carboxytetramethylrhodamine‐(methane thiosulfonate)) fluorescence. Moreover, Oxophench reduces the baseline fluorescence in oocytes and incorporates into the cell membrane while reducing the membrane fluidity of HEK293 cells. Our model calculations confirmed that Oxophench, a potent membrane‐bound quencher, modifies the VCF signal during conformational changes. These results support our previously published model of VCF signal generation and point out that a change in the VCF signal may not necessarily indicate an altered conformational transition of the investigated protein. LA - English DB - MTMT ER - TY - JOUR AU - Zákány, Florina AU - Mándity, István AU - Varga, Zoltán AU - Panyi, György AU - Nagy, Péter AU - Kovács, Tamás TI - Effect of the Lipid Landscape on the Efficacy of Cell-Penetrating Peptides JF - CELLS J2 - CELLS-BASEL VL - 12 PY - 2023 IS - 13 PG - 29 SN - 2073-4409 DO - 10.3390/cells12131700 UR - https://m2.mtmt.hu/api/publication/34037015 ID - 34037015 N1 - Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, 4032, Hungary Department of Organic Chemistry, Faculty of Pharmacy, Semmelweis University, Budapest, 1085, Hungary TTK Lendület Artificial Transporter Research Group, Institute of Materials and Environmental Chemistry, Research Centre for Natural Sciences, Budapest, 1117, Hungary Export Date: 16 October 2023 Correspondence Address: Nagy, P.; Department of Biophysics and Cell Biology, Hungary; email: nagyp@med.unideb.hu Correspondence Address: Kovacs, T.; Department of Biophysics and Cell Biology, Hungary; email: kovacs.tamas@med.unideb.hu AB - Every cell biological textbook teaches us that the main role of the plasma membrane is to separate cells from their neighborhood to allow for a controlled composition of the intracellular space. The mostly hydrophobic nature of the cell membrane presents an impenetrable barrier for most hydrophilic molecules larger than 1 kDa. On the other hand, cell-penetrating peptides (CPPs) are capable of traversing this barrier without compromising membrane integrity, and they can do so on their own or coupled to cargos. Coupling biologically and medically relevant cargos to CPPs holds great promise of delivering membrane-impermeable drugs into cells. If the cargo is able to interact with certain cell types, uptake of the CPP–drug complex can be tailored to be cell-type-specific. Besides outlining the major membrane penetration pathways of CPPs, this review is aimed at deciphering how properties of the membrane influence the uptake mechanisms of CPPs. By summarizing an extensive body of experimental evidence, we argue that a more ordered, less flexible membrane structure, often present in the very diseases planned to be treated with CPPs, decreases their cellular uptake. These correlations are not only relevant for understanding the cellular biology of CPPs, but also for rationally improving their value in translational or clinical applications. LA - English DB - MTMT ER - TY - JOUR AU - Szántó, Gábor Tibor AU - Papp, Ferenc AU - Zákány, Florina AU - Varga, Zoltán AU - Deutsch, Carol AU - Panyi, György TI - Molecular rearrangements in S6 during slow inactivation in Shaker -IR potassium channels JF - JOURNAL OF GENERAL PHYSIOLOGY J2 - J GEN PHYSIOL VL - 155 PY - 2023 IS - 7 PG - 14 SN - 0022-1295 DO - 10.1085/jgp.202313352 UR - https://m2.mtmt.hu/api/publication/34007263 ID - 34007263 AB - Voltage-gated K+ channels have distinct gates that regulate ion flux: the activation gate (A-gate) formed by the bundle crossing of the S6 transmembrane helices and the slow inactivation gate in the selectivity filter. These two gates are bidirectionally coupled. If coupling involves the rearrangement of the S6 transmembrane segment, then we predict state-dependent changes in the accessibility of S6 residues from the water-filled cavity of the channel with gating. To test this, we engineered cysteines, one at a time, at S6 positions A471, L472, and P473 in a T449A Shaker-IR background and determined the accessibility of these cysteines to cysteine-modifying reagents MTSET and MTSEA applied to the cytosolic surface of inside-out patches. We found that neither reagent modified either of the cysteines in the closed or the open state of the channels. On the contrary, A471C and P473C, but not L472C, were modified by MTSEA, but not by MTSET, if applied to inactivated channels with open A-gate (OI state). Our results, combined with earlier studies reporting reduced accessibility of residues I470C and V474C in the inactivated state, strongly suggest that the coupling between the A-gate and the slow inactivation gate is mediated by rearrangements in the S6 segment. The S6 rearrangements are consistent with a rigid rod-like rotation of S6 around its longitudinal axis upon inactivation. S6 rotation and changes in its environment are concomitant events in slow inactivation of Shaker KV channels. LA - English DB - MTMT ER - TY - JOUR AU - Nemes, Balázs AU - László, Szabolcs AU - Zsidó, Balázs Zoltán AU - Hetényi, Csaba AU - Fehér, Ádám AU - Papp, Ferenc AU - Varga, Zoltán AU - Szőke, Éva AU - Sándor, Zoltán AU - Pintér, Erika TI - Elucidation of the binding mode of organic polysulfides on the human TRPA1 receptor JF - FRONTIERS IN PHYSIOLOGY J2 - FRONT PHYSIOL VL - 14 PY - 2023 PG - 16 SN - 1664-042X DO - 10.3389/fphys.2023.1180896 UR - https://m2.mtmt.hu/api/publication/34006433 ID - 34006433 N1 - * Megosztott szerzőség AB - Introduction: Previous studies have established that endogenous inorganic polysulfides have significant biological actions activating the Transient Receptor Potential Ankyrin 1 (TRPA1) receptor. Organic polysulfides exert similar effects, but they are much more stable molecules, therefore these compounds are more suitable as drugs. In this study, we aimed to better understand the mechanism of action of organic polysulfides by identification of their binding site on the TRPA1 receptor. LA - English DB - MTMT ER - TY - JOUR AU - Szántó, Gábor Tibor AU - Fehér, Ádám AU - Korpos, Éva AU - Gyöngyösi, Adrienn AU - Kállai, Judit AU - Mészáros, Beáta AU - Ovari, Krisztian AU - Lányi, Árpád AU - Panyi, György AU - Varga, Zoltán TI - 5-Chloro-2-Guanidinobenzimidazole (ClGBI) Is a Non-Selective Inhibitor of the Human HV1 Channel JF - PHARMACEUTICALS J2 - PHARMACEUTICALS-BASE VL - 16 PY - 2023 IS - 5 SP - 656 SN - 1424-8247 DO - 10.3390/ph16050656 UR - https://m2.mtmt.hu/api/publication/33781207 ID - 33781207 AB - 5-chloro-2-guanidinobenzimidazole (ClGBI), a small-molecule guanidine derivative, is a known effective inhibitor of the voltage-gated proton (H+) channel (HV1, Kd ≈ 26 μM) and is widely used both in ion channel research and functional biological assays. However, a comprehensive study of its ion channel selectivity determined by electrophysiological methods has not been published yet. The lack of selectivity may lead to incorrect conclusions regarding the role of hHv1 in physiological or pathophysiological responses in vitro and in vivo. We have found that ClGBI inhibits the proliferation of lymphocytes, which absolutely requires the functioning of the KV1.3 channel. We, therefore, tested ClGBI directly on hKV1.3 using a whole-cell patch clamp and found an inhibitory effect similar in magnitude to that seen on hHV1 (Kd ≈ 72 μM). We then further investigated ClGBI selectivity on the hKV1.1, hKV1.4-IR, hKV1.5, hKV10.1, hKV11.1, hKCa3.1, hNaV1.4, and hNaV1.5 channels. Our results show that, besides HV1 and KV1.3, all other off-target channels were inhibited by ClGBI, with Kd values ranging from 12 to 894 μM. Based on our comprehensive data, ClGBI has to be considered a non-selective hHV1 inhibitor; thus, experiments aiming at elucidating the significance of these channels in physiological responses have to be carefully evaluated. LA - English DB - MTMT ER - TY - JOUR AU - Kovács, Zsigmond Máté AU - Óvári, József AU - Dienes, Csaba Bálint AU - Magyar, János AU - Bányász, Tamás AU - Nánási, Péter Pál AU - Horváth, Balázs AU - Fehér, Ádám AU - Varga, Zoltán AU - Szentandrássy, Norbert TI - ABT-333 (Dasabuvir) Increases Action Potential Duration and Provokes Early Afterdepolarizations in Canine Left Ventricular Cells via Inhibition of IKr JF - PHARMACEUTICALS J2 - PHARMACEUTICALS-BASE VL - 16 PY - 2023 IS - 4 PG - 18 SN - 1424-8247 DO - 10.3390/ph16040488 UR - https://m2.mtmt.hu/api/publication/33720502 ID - 33720502 AB - ABT-333 (dasabuvir) is an antiviral agent used in hepatitis C treatment. The molecule, similarly to some inhibitors of hERG channels, responsible for the delayed rectifier potassium current (IKr), contains the methanesulfonamide group. Reduced IKr current leads to long QT syndrome and early afterdepolarizations (EADs), therefore potentially causing life-threatening arrhythmias and sudden cardiac death. Our goal was to investigate the acute effects of ABT-333 in enzymatically isolated canine left ventricular myocardial cells. Action potentials (APs) and ion currents were recorded with a sharp microelectrode technique and whole-cell patch clamp, respectively. Application of 1 μM ABT-333 prolonged the AP in a reversible manner. The maximal rates of phases 0 and 1 were irreversibly decreased. Higher ABT-333 concentrations caused larger AP prolongation, elevation of the early plateau potential, and reduction of maximal rates of phases 0, 1, and 3. EADs occurred in some cells in 3–30 μM ABT-333 concentrations. The 10 μM ABT-333-sensitive current, recorded with AP voltage clamp, contained a late outward component corresponding to IKr and an early outward one corresponding to transient outward potassium current (Ito). ABT-333 reduced hERG-channel-mediated ion current in a concentration-dependent, partially reversible manner with a half-inhibitory concentration of 3.2 μM. As the therapeutic plasma concentration of ABT-333 is 1 nM, the arrhythmic risk of ABT-333 is very low, even in the case of drug overdose. LA - English DB - MTMT ER - TY - JOUR AU - Fehér, Ádám AU - Korpos, Éva AU - Piga, Martina AU - Tomasic, Tihomir AU - Zidar, Nace AU - Gyöngyösi, Adrienn AU - Kállai, Judit AU - Lányi, Árpád AU - Papp, Ferenc AU - Gyuris, Katinka AU - Varga, Zoltán TI - Identification of a new family of inhibitors of the human Hv1 proton channel JF - BIOPHYSICAL JOURNAL J2 - BIOPHYS J VL - 122 PY - 2023 IS - 3 SP - 256a EP - 257a SN - 0006-3495 DO - 10.1016/j.bpj.2022.11.1479 UR - https://m2.mtmt.hu/api/publication/33674323 ID - 33674323 LA - English DB - MTMT ER - TY - JOUR AU - Kovács, Tamás AU - Kurtan, Kitti AU - Varga, Zoltán AU - Nagy, Péter AU - Panyi, György AU - Zákány, Florina TI - Veklury® (remdesivir) formulations inhibit initial membrane‐coupled events of SARS‐CoV‐2 infection due to their sulfobutylether‐β‐cyclodextrin content JF - BRITISH JOURNAL OF PHARMACOLOGY J2 - BR J PHARMACOL VL - 180 PY - 2023 IS - 16 SP - 2064 EP - 2084 PG - 21 SN - 0007-1188 DO - 10.1111/bph.16063 UR - https://m2.mtmt.hu/api/publication/33671944 ID - 33671944 AB - Background and Purpose: Despite its contradictory clinical performance, remdesivir (Veklury®) has a pivotal role in COVID-19 therapy. Possible contributions of the vehicle, sulfobutylether-β-cyclodextrin (SBECD) to Veklury® effects have been overlooked. The powder and solution formulations of Veklury® are treated equivalently despite their different vehicle content. Our objective was to study Veklury® effects on initial membrane-coupled events of SARS-CoV-2 infection focusing on the cholesterol depletion-mediated role of SBECD. Experimental Approach: Using time-correlated flow cytometry and quantitative three-dimensional confocal microscopy, we studied early molecular events of SARS-CoV-2–host cell membrane interactions. Key Results: Veklury® and different cholesterol-depleting cyclodextrins (CDs) reduced binding of the spike receptor-binding domain (RBD) to ACE2 and spike trimer internalization for Wuhan-Hu-1, Delta and Omicron variants. Correlations of these effects with cholesterol-dependent changes in membrane structure and decreased lipid raft-dependent ACE2–TMPRSS2 interaction establish that SBECD is not simply a vehicle but also an effector along with remdesivir due to its cholesterol-depleting potential. Veklury® solution inhibited RBD binding more efficiently due to its twice higher SBECD content. The CD-induced inhibitory effects were more prominent at lower RBD concentrations and in cells with lower endogenous ACE2 expression, indicating that the supportive CD actions can be even more pronounced during in vivo infection when viral load and ACE expression are typically low. Conclusion and Implications: Our findings call for the differentiation of Veklury® formulations in meta-analyses of clinical trials, potentially revealing neglected benefits of the solution formulation, and also raise the possibility of adjuvant cyclodextrin (CD) therapy, even at higher doses, in COVID-19. LA - English DB - MTMT ER - TY - JOUR AU - Fehér, Ádám AU - Pethő, Zoltán Dénes AU - Szántó, Gábor Tibor AU - Klekner, Álmos AU - Tajti, Gábor AU - Batta, Gyula Gábor (Ifj.) AU - Hortobágyi, Tibor AU - Varga, Zoltán AU - Schwab, Albrecht AU - Panyi, György TI - Mapping the functional expression of auxiliary subunits of KCa1.1 in glioblastoma JF - SCIENTIFIC REPORTS J2 - SCI REP VL - 12 PY - 2022 IS - 1 PG - 14 SN - 2045-2322 DO - 10.1038/s41598-022-26196-w UR - https://m2.mtmt.hu/api/publication/33398474 ID - 33398474 AB - Glioblastoma (GBM) is the most aggressive glial tumor, where ion channels, including K Ca 1.1, are candidates for new therapeutic options. Since the auxiliary subunits linked to K Ca 1.1 in GBM are largely unknown we used electrophysiology combined with pharmacology and gene silencing to address the functional expression of K Ca 1.1/ β subunits complexes in both primary tumor cells and in the glioblastoma cell line U-87 MG. The pattern of the sensitivity (activation/inhibition) of the whole-cell currents to paxilline, lithocholic acid, arachidonic acid, and iberiotoxin; the presence of inactivation of the whole-cell current along with the loss of the outward rectification upon exposure to the reducing agent DTT collectively argue that K Ca 1.1/β3 complex is expressed in U-87 MG. Similar results were found using human primary glioblastoma cells isolated from patient samples. Silencing the β3 subunit expression inhibited carbachol-induced Ca 2+ transients in U-87 MG thereby indicating the role of the K Ca 1.1/β3 in the Ca 2+ signaling of glioblastoma cells. Functional expression of the K Ca 1.1/β3 complex, on the other hand, lacks cell cycle dependence. We suggest that the K Ca 1.1/β3 complex may have diagnostic and therapeutic potential in glioblastoma in the future. LA - English DB - MTMT ER - TY - JOUR AU - Kovács, Tamás AU - Nagy, Péter AU - Panyi, György AU - Szente, Lajos AU - Varga, Zoltán AU - Zákány, Florina TI - Cyclodextrins: Only Pharmaceutical Excipients or Full-Fledged Drug Candidates? JF - PHARMACEUTICS J2 - PHARMACEUTICS VL - 14 PY - 2022 PG - 36 SN - 1999-4923 DO - 10.3390/pharmaceutics14122559 UR - https://m2.mtmt.hu/api/publication/33274154 ID - 33274154 N1 - Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, Debrecen, H-4032, Hungary CycloLab Cyclodextrin R & D Laboratory Ltd, Budapest, H-1097, Hungary Export Date: 2 March 2023 Correspondence Address: Zakany, F.; Department of Biophysics and Cell Biology, Hungary; email: florina.zakany@med.unideb.hu AB - Cyclodextrins, representing a versatile family of cyclic oligosaccharides, have extensive pharmaceutical applications due to their unique truncated cone-shaped structure with a hydrophilic outer surface and a hydrophobic cavity, which enables them to form non-covalent host–guest inclusion complexes in pharmaceutical formulations to enhance the solubility, stability and bioavailability of numerous drug molecules. As a result, cyclodextrins are mostly considered as inert carriers during their medical application, while their ability to interact not only with small molecules but also with lipids and proteins is largely neglected. By forming inclusion complexes with cholesterol, cyclodextrins deplete cholesterol from cellular membranes and thereby influence protein function indirectly through alterations in biophysical properties and lateral heterogeneity of bilayers. In this review, we summarize the general chemical principles of direct cyclodextrin–protein interactions and highlight, through relevant examples, how these interactions can modify protein functions in vivo, which, despite their huge potential, have been completely unexploited in therapy so far. Finally, we give a brief overview of disorders such as Niemann–Pick type C disease, atherosclerosis, Alzheimer’s and Parkinson’s disease, in which cyclodextrins already have or could have the potential to be active therapeutic agents due to their cholesterol-complexing or direct protein-targeting properties. LA - English DB - MTMT ER -