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  1. Article ; Online: Mechanisms underlying drug-mediated regulation of membrane protein function.

    Rusinova, Radda / He, Changhao / Andersen, Olaf S

    Proceedings of the National Academy of Sciences of the United States of America

    2021  Volume 118, Issue 46

    Abstract: The hydrophobic coupling between membrane proteins and their host lipid bilayer provides a mechanism by which bilayer-modifying drugs may alter protein function. Drug regulation of membrane protein function thus may be mediated by both direct ... ...

    Abstract The hydrophobic coupling between membrane proteins and their host lipid bilayer provides a mechanism by which bilayer-modifying drugs may alter protein function. Drug regulation of membrane protein function thus may be mediated by both direct interactions with the protein and drug-induced alterations of bilayer properties, in which the latter will alter the energetics of protein conformational changes. To tease apart these mechanisms, we examine how the prototypical, proton-gated bacterial potassium channel KcsA is regulated by bilayer-modifying drugs using a fluorescence-based approach to quantify changes in both KcsA function and lipid bilayer properties (using gramicidin channels as probes). All tested drugs inhibited KcsA activity, and the changes in the different gating steps varied with bilayer thickness, suggesting a coupling to the bilayer. Examining the correlations between changes in KcsA gating steps and bilayer properties reveals that drug-induced regulation of membrane protein function indeed involves bilayer-mediated mechanisms. Both direct, either specific or nonspecific, binding and bilayer-mediated mechanisms therefore are likely to be important whenever there is overlap between the concentration ranges at which a drug alters membrane protein function and bilayer properties. Because changes in bilayer properties will impact many diverse membrane proteins, they may cause indiscriminate changes in protein function.
    MeSH term(s) Cell Membrane/drug effects ; Cell Membrane/metabolism ; Drug and Narcotic Control/methods ; Gramicidin/pharmacology ; Hydrophobic and Hydrophilic Interactions ; Lipid Bilayers/metabolism ; Membrane Proteins/metabolism ; Pharmaceutical Preparations/metabolism ; Potassium Channels/metabolism
    Chemical Substances Lipid Bilayers ; Membrane Proteins ; Pharmaceutical Preparations ; Potassium Channels ; Gramicidin (1405-97-6)
    Language English
    Publishing date 2021-10-25
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2113229118
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Capsaicin as an amphipathic modulator of Na

    Cowan, Luke M / Strege, Peter R / Rusinova, Radda / Andersen, Olaf S / Farrugia, Gianrico / Beyder, Arthur

    Channels (Austin, Tex.)

    2022  Volume 16, Issue 1, Page(s) 9–26

    Abstract: ... ...

    Abstract SCN5A
    MeSH term(s) Capsaicin/pharmacology ; Channelopathies ; Humans ; Myocytes, Cardiac/metabolism ; NAV1.5 Voltage-Gated Sodium Channel ; Sodium/metabolism
    Chemical Substances NAV1.5 Voltage-Gated Sodium Channel ; Sodium (9NEZ333N27) ; Capsaicin (S07O44R1ZM)
    Language English
    Publishing date 2022-04-12
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2262854-X
    ISSN 1933-6969 ; 1933-6969
    ISSN (online) 1933-6969
    ISSN 1933-6969
    DOI 10.1080/19336950.2022.2026015
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Regulation of Gramicidin Channel Function Solely by Changes in Lipid Intrinsic Curvature.

    Maer, Andreia M / Rusinova, Radda / Providence, Lyndon L / Ingólfsson, Helgi I / Collingwood, Shemille A / Lundbæk, Jens A / Andersen, Olaf S

    Frontiers in physiology

    2022  Volume 13, Page(s) 836789

    Abstract: Membrane protein function is regulated by the lipid bilayer composition. In many cases the changes in function correlate with changes in the lipid intrinsic curvature ( ...

    Abstract Membrane protein function is regulated by the lipid bilayer composition. In many cases the changes in function correlate with changes in the lipid intrinsic curvature (
    Language English
    Publishing date 2022-03-08
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2564217-0
    ISSN 1664-042X
    ISSN 1664-042X
    DOI 10.3389/fphys.2022.836789
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article: Nonspecific membrane bilayer perturbations by ivermectin underlie SARS-CoV-2

    Eastman, Richard T / Rusinova, Radda / Herold, Karl F / Huang, Xi-Ping / Dranchak, Patricia / Voss, Ty C / Rana, Sandeep / Shrimp, Jonathan H / White, Alex D / Hemmings, Hugh C / Roth, Bryan L / Inglese, James / Andersen, Olaf S / Dahlin, Jayme L

    bioRxiv : the preprint server for biology

    2023  

    Abstract: Since it was proposed as a potential host-directed antiviral agent for SARS-CoV-2, the antiparasitic drug ivermectin has been investigated thoroughly in clinical trials, which have provided insufficient support for its clinical efficacy. To examine the ... ...

    Abstract Since it was proposed as a potential host-directed antiviral agent for SARS-CoV-2, the antiparasitic drug ivermectin has been investigated thoroughly in clinical trials, which have provided insufficient support for its clinical efficacy. To examine the potential for ivermectin to be repurposed as an antiviral agent, we therefore undertook a series of preclinical studies. Consistent with early reports, ivermectin decreased SARS-CoV-2 viral burden in
    Language English
    Publishing date 2023-10-24
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.10.23.563088
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Stopped-Flow Fluorometric Ion Flux Assay for Ligand-Gated Ion Channel Studies.

    Posson, David J / Rusinova, Radda / Andersen, Olaf S / Nimigean, Crina M

    Methods in molecular biology (Clifton, N.J.)

    2017  Volume 1684, Page(s) 223–235

    Abstract: Quantitative investigations into functional properties of purified ion channel proteins using standard electrophysiological methods are challenging, in particular for the determination of average ion channel behavior following rapid changes in ... ...

    Abstract Quantitative investigations into functional properties of purified ion channel proteins using standard electrophysiological methods are challenging, in particular for the determination of average ion channel behavior following rapid changes in experimental conditions (e.g., ligand concentration). Here, we describe a method for determining the functional activity of liposome-reconstituted K
    MeSH term(s) Animals ; Fats/chemistry ; Fluorometry ; Humans ; Ligand-Gated Ion Channels/metabolism ; Lipid Bilayers/metabolism ; Liposomes/metabolism ; Potassium Channels/metabolism
    Chemical Substances Fats ; Ligand-Gated Ion Channels ; Lipid Bilayers ; Liposomes ; Potassium Channels ; tallow (98HPY76U4W)
    Language English
    Publishing date 2017-10-20
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-4939-7362-0_17
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Therapeutic antibody activation of the glucocorticoid-induced TNF receptor by a clustering mechanism.

    He, Changhao / Maniyar, Rachana R / Avraham, Yahel / Zappasodi, Roberta / Rusinova, Radda / Newman, Walter / Heath, Heidi / Wolchok, Jedd D / Dahan, Rony / Merghoub, Taha / Meyerson, Joel R

    Science advances

    2022  Volume 8, Issue 8, Page(s) eabm4552

    Abstract: GITR is a TNF receptor, and its activation promotes immune responses and drives antitumor activity. The receptor is activated by the GITR ligand (GITRL), which is believed to cluster receptors into a high-order array. Immunotherapeutic agonist antibodies ...

    Abstract GITR is a TNF receptor, and its activation promotes immune responses and drives antitumor activity. The receptor is activated by the GITR ligand (GITRL), which is believed to cluster receptors into a high-order array. Immunotherapeutic agonist antibodies also activate the receptor, but their mechanisms are not well characterized. We solved the structure of full-length mouse GITR bound to Fabs from the antibody DTA-1. The receptor is a dimer, and each subunit binds one Fab in an orientation suggesting that the antibody clusters receptors. Binding experiments with purified proteins show that DTA-1 IgG and GITRL both drive extensive clustering of GITR. Functional data reveal that DTA-1 and the anti-human GITR antibody TRX518 activate GITR in their IgG forms but not as Fabs. Thus, the divalent character of the IgG agonists confers an ability to mimic GITRL and cluster and activate GITR. These findings will inform the clinical development of this class of antibodies for immuno-oncology.
    Language English
    Publishing date 2022-02-25
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2810933-8
    ISSN 2375-2548 ; 2375-2548
    ISSN (online) 2375-2548
    ISSN 2375-2548
    DOI 10.1126/sciadv.abm4552
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: A general mechanism for drug promiscuity: Studies with amiodarone and other antiarrhythmics.

    Rusinova, Radda / Koeppe, Roger E / Andersen, Olaf S

    The Journal of general physiology

    2015  Volume 146, Issue 6, Page(s) 463–475

    Abstract: Amiodarone is a widely prescribed antiarrhythmic drug used to treat the most prevalent type of arrhythmia, atrial fibrillation (AF). At therapeutic concentrations, amiodarone alters the function of many diverse membrane proteins, which results in complex ...

    Abstract Amiodarone is a widely prescribed antiarrhythmic drug used to treat the most prevalent type of arrhythmia, atrial fibrillation (AF). At therapeutic concentrations, amiodarone alters the function of many diverse membrane proteins, which results in complex therapeutic and toxicity profiles. Other antiarrhythmics, such as dronedarone, similarly alter the function of multiple membrane proteins, suggesting that a multipronged mechanism may be beneficial for treating AF, but raising questions about how these antiarrhythmics regulate a diverse range of membrane proteins at similar concentrations. One possible mechanism is that these molecules regulate membrane protein function by altering the common environment provided by the host lipid bilayer. We took advantage of the gramicidin (gA) channels' sensitivity to changes in bilayer properties to determine whether commonly used antiarrhythmics--amiodarone, dronedarone, propranolol, and pindolol, whose pharmacological modes of action range from multi-target to specific--perturb lipid bilayer properties at therapeutic concentrations. Using a gA-based fluorescence assay, we found that amiodarone and dronedarone are potent bilayer modifiers at therapeutic concentrations; propranolol alters bilayer properties only at supratherapeutic concentration, and pindolol has little effect. Using single-channel electrophysiology, we found that amiodarone and dronedarone, but not propranolol or pindolol, increase bilayer elasticity. The overlap between therapeutic and bilayer-altering concentrations, which is observed also using plasma membrane-like lipid mixtures, underscores the need to explore the role of the bilayer in therapeutic as well as toxic effects of antiarrhythmic agents.
    MeSH term(s) Amiodarone/adverse effects ; Amiodarone/pharmacology ; Anti-Arrhythmia Agents/adverse effects ; Anti-Arrhythmia Agents/pharmacology ; Elasticity ; Lipid Bilayers/chemistry ; Lipid Bilayers/metabolism ; Membrane Proteins/drug effects
    Chemical Substances Anti-Arrhythmia Agents ; Lipid Bilayers ; Membrane Proteins ; Amiodarone (N3RQ532IUT)
    Language English
    Publishing date 2015-12
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 3118-5
    ISSN 1540-7748 ; 0022-1295
    ISSN (online) 1540-7748
    ISSN 0022-1295
    DOI 10.1085/jgp.201511470
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Calcium ions open a selectivity filter gate during activation of the MthK potassium channel.

    Posson, David J / Rusinova, Radda / Andersen, Olaf S / Nimigean, Crina M

    Nature communications

    2015  Volume 6, Page(s) 8342

    Abstract: Ion channel opening and closing are fundamental to cellular signalling and homeostasis. Gates that control K(+) channel activity were found both at an intracellular pore constriction and within the selectivity filter near the extracellular side but the ... ...

    Abstract Ion channel opening and closing are fundamental to cellular signalling and homeostasis. Gates that control K(+) channel activity were found both at an intracellular pore constriction and within the selectivity filter near the extracellular side but the specific location of the gate that opens Ca(2+)-activated K(+) channels has remained elusive. Using the Methanobacterium thermoautotrophicum homologue (MthK) and a stopped-flow fluorometric assay for fast channel activation, we show that intracellular quaternary ammonium blockers bind to closed MthK channels. Since the blockers are known to bind inside a central channel cavity, past the intracellular entryway, the gate must be within the selectivity filter. Furthermore, the blockers access the closed channel slower than the open channel, suggesting that the intracellular entryway narrows upon pore closure, without preventing access of either the blockers or the smaller K(+). Thus, Ca(2+)-dependent gating in MthK occurs at the selectivity filter with coupled movement of the intracellular helices.
    MeSH term(s) Calcium/metabolism ; Kinetics ; Methanobacterium/metabolism ; Potassium Channels/metabolism ; Quaternary Ammonium Compounds
    Chemical Substances Potassium Channels ; Quaternary Ammonium Compounds ; tetrapentylammonium (9IKH79PSWL) ; Calcium (SY7Q814VUP)
    Language English
    Publishing date 2015-09-23
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/ncomms9342
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: Regulation of ion channel function by the host lipid bilayer examined by a stopped-flow spectrofluorometric assay.

    Rusinova, Radda / Kim, Dorothy M / Nimigean, Crina M / Andersen, Olaf S

    Biophysical journal

    2014  Volume 106, Issue 5, Page(s) 1070–1078

    Abstract: To examine the function of ligand-gated ion channels in a defined membrane environment, we developed a robust sequential-mixing fluorescence-based stopped-flow assay. Channel activity is determined using a channel-permeable quencher (e.g., thallium, Tl(+) ...

    Abstract To examine the function of ligand-gated ion channels in a defined membrane environment, we developed a robust sequential-mixing fluorescence-based stopped-flow assay. Channel activity is determined using a channel-permeable quencher (e.g., thallium, Tl(+)) of a water-soluble fluorophore (8-aminonaphthalene-1,3,6-trisulfonic acid) encapsulated in large unilamellar vesicles in which the channel of interest has been reconstituted, which allows for rapid solution changes. To validate the method, we explored the activation of wild-type KcsA channel, as well as it's noninactivating (E71A) KcsA mutant, by extravesicular protons (H(+)). For both channel types, the day-to-day variability in the reconstitution yield (as judged from the time course of fluorescence quenching) is <10%. The activation curve for E71A KcsA is similar to that obtained previously using single-channel electrophysiology, and the activation curves for wild-type and E71A KcsA are indistinguishable, indicating that channel activation and inactivation are separate processes. We then investigated the regulation of KcsA activation by changes in lipid bilayer composition. Increasing the acyl chain length (from C18:1 to C22:1 in diacylphosphatidylcholine), but not the mole fraction of POPG (>0.25) in the bilayer-forming phospholipid mixture, alters KcsA H(+) gating. The bilayer-thickness-dependent shift in the activation curve is suggestive of a decrease in an apparent H(+) affinity and cooperativity. The control over bilayer environment and time resolution makes this method a powerful assay for exploring ligand activation and inactivation of ion channels, and how channel gating varies with changes in the channels' lipid bilayer environment or other regulatory processes.
    MeSH term(s) Ion Channel Gating ; Lipid Bilayers/chemistry ; Lipid Bilayers/metabolism ; Phospholipids/metabolism ; Potassium Channels/metabolism ; Spectrometry, Fluorescence/methods
    Chemical Substances Lipid Bilayers ; Phospholipids ; Potassium Channels
    Language English
    Publishing date 2014-03-07
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 218078-9
    ISSN 1542-0086 ; 0006-3495
    ISSN (online) 1542-0086
    ISSN 0006-3495
    DOI 10.1016/j.bpj.2014.01.027
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Nonspecific membrane bilayer perturbations by ivermectin underlie SARS-CoV-2 in vitro activity

    Eastman, Richard T / Rusinova, Radda / Herold, Karl F / Huang, Xi-Ping / Dranchak, Patricia / Voss, Ty C / Rana, Sandeep / Shrimp, Jonathan H / White, Alex D / Hemmings, Hugh C / Roth, Bryan L / Inglese, James / Andersen, Olaf S / Dahlin, Jayme L

    bioRxiv

    Abstract: Since it was proposed as a potential host-directed antiviral agent for SARS-CoV-2, the antiparasitic drug ivermectin has been investigated thoroughly in clinical trials, which have provided insufficient support for its clinical efficacy. To examine the ... ...

    Abstract Since it was proposed as a potential host-directed antiviral agent for SARS-CoV-2, the antiparasitic drug ivermectin has been investigated thoroughly in clinical trials, which have provided insufficient support for its clinical efficacy. To examine the potential for ivermectin to be repurposed as an antiviral agent, we therefore undertook a series of preclinical studies. Consistent with early reports, ivermectin decreased SARS-CoV-2 viral burden in in vitro models at low micromolar concentrations, five- to ten-fold higher than the reported toxic clinical concentration. At similar concentrations, ivermectin also decreased cell viability and increased biomarkers of cytotoxicity and apoptosis. Further mechanistic and profiling studies revealed that ivermectin nonspecifically perturbs membrane bilayers at the same concentrations where it decreases the SARS-CoV-2 viral burden, resulting in nonspecific modulation of membrane-based targets such as G-protein coupled receptors and ion channels. These results suggest that a primary molecular mechanism for the in vitro antiviral activity of ivermectin may be nonspecific membrane perturbation, indicating that ivermectin is unlikely to be translatable into a safe and effective antiviral agent. These results and experimental workflow provide a useful paradigm for performing preclinical studies on (pandemic-related) drug repurposing candidates.
    Keywords covid19
    Language English
    Publishing date 2023-10-24
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2023.10.23.563088
    Database COVID19

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