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Macias-Contreras M, Granados JP, Hernandez DS. ION Thallos-HTL: a fluorescent thallium indicator that enables cell-selective and localizable thallium flux assays. Org Biomol Chem 2024; 22:4748-4756. [PMID: 38804097 DOI: 10.1039/d4ob00535j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Ion channels are essential proteins for all organisms. Electrophysiology is a useful and commonly employed method to study ion channels, however there is a need for operationally simpler, cost-effective and higher throughput techniques to study ion channel functions in their native environments. Fluorescent ion indicators, such as Fluo-4 and Thallos, have been used for decades to study ion channel activity by measuring the flux of ions through channels of interest. In this work, we present ION Thallos-HTL, a thallium indicator that can be localized using HaloTag technology. This novel indicator enables specific labeling of cells and intracellular compartments in live cells and responds to changes in thallium concentration within these environments. We demonstrate the utility of ION Thallos-HTL by conducting a thallium flux assay using high-throughput instrumentation in a mixed cell population where some cells are expressing HaloTag and some are not.
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Lyon M, Li P, Ferreira JJ, Lazarenko RM, Kharade SV, Kramer M, McClenahan SJ, Days E, Bauer JA, Spitznagel BD, Weaver CD, Borrego Alvarez A, Puga Molina LC, Lybaert P, Khambekar S, Liu A, Lindsley CW, Denton J, Santi CM. A selective inhibitor of the sperm-specific potassium channel SLO3 impairs human sperm function. Proc Natl Acad Sci U S A 2023; 120:e2212338120. [PMID: 36649421 PMCID: PMC9942793 DOI: 10.1073/pnas.2212338120] [Citation(s) in RCA: 18] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 12/12/2022] [Indexed: 01/19/2023] Open
Abstract
To fertilize an oocyte, the membrane potential of both mouse and human sperm must hyperpolarize (become more negative inside). Determining the molecular mechanisms underlying this hyperpolarization is vital for developing new contraceptive methods and detecting causes of idiopathic male infertility. In mouse sperm, hyperpolarization is caused by activation of the sperm-specific potassium (K+) channel SLO3 [C. M. Santi et al., FEBS Lett. 584, 1041-1046 (2010)]. In human sperm, it has long been unclear whether hyperpolarization depends on SLO3 or the ubiquitous K+ channel SLO1 [N. Mannowetz, N. M. Naidoo, S. A. S. Choo, J. F. Smith, P. V. Lishko, Elife 2, e01009 (2013), C. Brenker et al., Elife 3, e01438 (2014), and S. A. Mansell, S. J. Publicover, C. L. R. Barratt, S. M. Wilson, Mol. Hum. Reprod. 20, 392-408 (2014)]. In this work, we identified the first selective inhibitor for human SLO3-VU0546110-and showed that it completely blocked heterologous SLO3 currents and endogenous K+ currents in human sperm. This compound also prevented sperm from hyperpolarizing and undergoing hyperactivated motility and induced acrosome reaction, which are necessary to fertilize an egg. We conclude that SLO3 is the sole K+ channel responsible for hyperpolarization and significantly contributes to the fertilizing ability of human sperm. Moreover, SLO3 is a good candidate for contraceptive development, and mutation of this gene is a possible cause of idiopathic male infertility.
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Affiliation(s)
- Maximilian Lyon
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Ping Li
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Juan J. Ferreira
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Roman M. Lazarenko
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN37232
| | - Sujay V. Kharade
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN37232
| | - Meghan Kramer
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN37232
| | | | - Emily Days
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN37232
| | - Joshua A. Bauer
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN37232
| | | | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, TN37232
| | - Aluet Borrego Alvarez
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Lis C. Puga Molina
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Pascale Lybaert
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
- Laboratoire de recherche en Reproduction humaine, Université Libre de Bruxelles, Bruxelles1050, Belgium
| | - Saayli Khambekar
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Alicia Liu
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
| | - Craig W. Lindsley
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN37232
- Department of Pharmacology, Vanderbilt University, Nashville, TN37232
| | - Jerod Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN37232
- Vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, TN37232
- Department of Pharmacology, Vanderbilt University, Nashville, TN37232
| | - Celia M. Santi
- Department of Obstetrics and Gynecology, Washington University School of Medicine, St. Louis, MO63110
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Inhibition of SARS-CoV-2 Viral Channel Activity Using FDA-Approved Channel Modulators Independent of Variants. Biomolecules 2022; 12:biom12111673. [PMID: 36421688 PMCID: PMC9687591 DOI: 10.3390/biom12111673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/29/2022] [Accepted: 11/07/2022] [Indexed: 11/16/2022] Open
Abstract
Background: SARS-CoV-2 has undergone mutations, yielding clinically relevant variants. Hypothesis: We hypothesized that in SARS-CoV-2, two highly conserved Orf3a and E channels directly related to the virus replication were a target for the detection and inhibition of the viral replication, independent of the variant, using FDA-approved ion channel modulators. Methods: A combination of a fluorescence potassium ion assay with channel modulators was developed to detect SARS-CoV-2 Orf3a/E channel activity. Two FDA-approved drugs, amantadine (an antiviral) and amitriptyline (an antidepressant), which are ion channel blockers, were tested as to whether they inhibited Orf3a/E channel activity in isolated virus variants and in nasal swab samples from COVID-19 patients. The variants were confirmed by PCR sequencing. Results: In isolated SARS-CoV-2 Alpha, Beta, and Delta variants, the channel activity of Orf3a/E was detected and inhibited by emodin and gliclazide (IC50 = 0.42 mM). In the Delta swab samples, amitriptyline and amantadine inhibited the channel activity of viral proteins, with IC50 values of 0.73 mM and 1.11 mM, respectively. In the Omicron swab samples, amitriptyline inhibited the channel activity, with an IC50 of 0.76 mM. Conclusions: We developed an efficient method to screen FDA-approved ion channel modulators that could be repurposed to detect and inhibit SARS-CoV-2 viral replication, independent of variants.
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McClenahan SJ, Kent CN, Kharade SV, Isaeva E, Williams JC, Han C, Terker A, Gresham R, Lazarenko RM, Days EL, Romaine IM, Bauer JA, Boutaud O, Sulikowski GA, Harris R, Weaver CD, Staruschenko A, Lindsley CW, Denton JS. VU6036720: The First Potent and Selective In Vitro Inhibitor of Heteromeric Kir4.1/5.1 Inward Rectifier Potassium Channels. Mol Pharmacol 2022; 101:357-370. [PMID: 35246480 PMCID: PMC9092466 DOI: 10.1124/molpharm.121.000464] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 02/14/2022] [Indexed: 01/14/2023] Open
Abstract
Heteromeric Kir4.1/Kir5.1 (KCNJ10/KCNJ16) inward rectifier potassium (Kir) channels play key roles in the brain and kidney, but pharmacological tools for probing their physiology and therapeutic potential have not been developed. Here, we report the discovery, in a high-throughput screening of 80,475 compounds, of the moderately potent and selective inhibitor VU0493690, which we selected for characterization and chemical optimization. VU0493690 concentration-dependently inhibits Kir4.1/5.1 with an IC50 of 0.96 μM and exhibits at least 10-fold selectivity over Kir4.1 and ten other Kir channels. Multidimensional chemical optimization of VU0493690 led to the development of VU6036720, the most potent (IC50 = 0.24 μM) and selective (>40-fold over Kir4.1) Kir4.1/5.1 inhibitor reported to date. Cell-attached patch single-channel recordings revealed that VU6036720 inhibits Kir4.1/5.1 activity through a reduction of channel open-state probability and single-channel current amplitude. Elevating extracellular potassium ion by 20 mM shifted the IC50 6.8-fold, suggesting that VU6036720 is a pore blocker that binds in the ion-conduction pathway. Mutation of the "rectification controller" asparagine 161 to glutamate (N161E), which is equivalent to small-molecule binding sites in other Kir channels, led to a strong reduction of inhibition by VU6036720. Renal clearance studies in mice failed to show a diuretic response that would be consistent with inhibition of Kir4.1/5.1 in the renal tubule. Drug metabolism and pharmacokinetics profiling revealed that high VU6036720 clearance and plasma protein binding may prevent target engagement in vivo. In conclusion, VU6036720 represents the current state-of-the-art Kir4.1/5.1 inhibitor that should be useful for probing the functions of Kir4.1/5.1 in vitro and ex vivo. SIGNIFICANCE STATEMENT: Heteromeric inward rectifier potassium (Kir) channels comprising Kir4.1 and Kir5.1 subunits play important roles in renal and neural physiology and may represent inhibitory drug targets for hypertension and edema. Herein, we employ high-throughput compound library screening, patch clamp electrophysiology, and medicinal chemistry to develop and characterize the first potent and specific in vitro inhibitor of Kir4.1/5.1, VU6036720, which provides proof-of-concept that drug-like inhibitors of this channel may be developed.
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Affiliation(s)
- Samantha J McClenahan
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Caitlin N Kent
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Sujay V Kharade
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Elena Isaeva
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Jade C Williams
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Changho Han
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Andrew Terker
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Robert Gresham
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Roman M Lazarenko
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Emily L Days
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Ian M Romaine
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Joshua A Bauer
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Olivier Boutaud
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Gary A Sulikowski
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Raymond Harris
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - C David Weaver
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Alexander Staruschenko
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Craig W Lindsley
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
| | - Jerod S Denton
- Departments of Anesthesiology (S.J.M., S.V.K., R.G., R.M.L., J.S.D.), Biochemistry (J.A.B.), Chemistry (C.N.K., J.C.W., I.M.R., C.D.W., G.A.S., C.W.L.), Pharmacology (E.L.D., C.D.W., C.W.L., C.H., O.B., J.S.D.), and Nephrology (A.T., R.H.), and Vanderbilt Institute of Chemical Biology (J.A.B., G.S., C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Cell Biology, Neurobiology and Anatomy, Medical College of Wisconsin, Milwaukee, Wisconsin (E.I.); and Department of Molecular Pharmacology and Physiology, University of South Florida, Tampa, Florida (A.S.)
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Novel inhibitors of the renal inward rectifier potassium channel of the mosquito vector Aedes aegypti. Future Med Chem 2021; 13:2015-2025. [PMID: 34590494 DOI: 10.4155/fmc-2021-0189] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The mosquito continues to be the most lethal animal to humans due to the devastating diseases that it carries and transmits. Controlling mosquito-borne diseases relies heavily on vector management using neurotoxic insecticides with limited modes of action. This has led to the emergence of resistance to pyrethroids and other neurotoxic insecticides in mosquitoes, which has reduced the efficacy of chemical control agents. Moreover, many neurotoxic insecticides are not selective for mosquitoes and negatively impact beneficial insects such as honeybees. Developing new mosquitocides with novel mechanisms of action is a clear unmet medical need; this review covers the efforts made toward this end by targeting the renal inward rectifier potassium channel (Kir) of the mosquito.
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Yu HG, Sizemore G, Smoot K, Perrotta P. Detecting SARS-CoV-2 Orf3a and E ion channel activity in COVID-19 blood samples. J Clin Transl Sci 2021; 5:e196. [PMID: 34873451 PMCID: PMC8632412 DOI: 10.1017/cts.2021.856] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 09/02/2021] [Accepted: 09/06/2021] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND SARS-CoV-2 has been found in the heart of COVID-19 patients. It is unclear how the virus passes from the upper respiratory tract to the myocardium. We hypothesized that SARS-CoV-2 is present in the blood of COVID-19 infected patients, spreading to other organs such as heart. METHODS We targeted two viroporins, Orf3a and E, in SARS-CoV-2. Orf3a and E form non-voltage-gated ion channels. A combined fluorescence potassium ion assay with three channel modulators (4-aminopyridine, emodin-Orf3a channel blocker, and gliclazide-E channel blocker) was developed to detect SARS-CoV-2 Orf3a/E channel activity. In blood samples, we subtracted the fluorescence signals in the absence and presence of emodin/gliclazide to detect Orf3a and E channel activity. RESULTS In lentivirus-spiked samples, we detected significant channel activity of Orf3a/E based on increase in fluorescence induced by 4-aminopyridine, and this increase in fluorescence was inhibited by emodin and gliclazide. In 18 antigen/PCR-positive samples, our test results found 15 are positive, demonstrating 83.3% concordance. In 24 antigen/PCR-negative samples, our test results found 21 are negative, showing 87.5% concordance. CONCLUSIONS We developed a cell-free test that can detect Orf3a/E channel activity of SARS-CoV-2 in blood samples from COVID-19-infected individuals, confirming a hypothesis that the virus spreads to the heart via blood circulation.
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Affiliation(s)
- Han-Gang Yu
- Department of Physiology and Pharmacology, School of Medicine, West Virginia University, Morgantown, WV, USA
| | | | - Katy Smoot
- Department of Pathology, Anatomy and Laboratory Medicine, School of Medicine, West Virginia University, Morgantown, WV, USA
| | - Peter Perrotta
- Department of Pathology, Anatomy and Laboratory Medicine, School of Medicine, West Virginia University, Morgantown, WV, USA
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Dutter BF, Ender A, Sulikowski GA, Weaver CD. Rhodol-based thallium sensors for cellular imaging of potassium channel activity. Org Biomol Chem 2019; 16:5575-5579. [PMID: 30051127 DOI: 10.1039/c8ob01098f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Thallium (Tl+) flux assays enable imaging of potassium (K+) channel activity in cells and tissues by exploiting the permeability of K+ channels to Tl+ coupled with a fluorescent Tl+ sensitive dye. Common Tl+ sensing dyes utilize fluorescein as the fluorophore though fluorescein exhibits certain undesirable properties in these assays including short excitation wavelengths and pH sensitivity. To overcome these drawbacks, the replacement of fluorescein with rhodols was investigated. A library of 13 rhodol-based Tl+ sensors was synthesized and their properties and performance in Tl+ flux assays evaluated. The dimethyl rhodol Tl+ sensor emerged as the best of the series and performed comparably to fluorescein-based sensors while demonstrating greater pH tolerance in the physiological range and excitation and emission spectra 30 nm red-shifted from fluorescein.
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Affiliation(s)
- Brendan F Dutter
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.
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Kozek KA, Du Y, Sharma S, Prael FJ, Spitznagel BD, Kharade SV, Denton JS, Hopkins CR, Weaver CD. Discovery and Characterization of VU0529331, a Synthetic Small-Molecule Activator of Homomeric G Protein-Gated, Inwardly Rectifying, Potassium (GIRK) Channels. ACS Chem Neurosci 2019; 10:358-370. [PMID: 30136838 PMCID: PMC6528656 DOI: 10.1021/acschemneuro.8b00287] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
G protein-gated, inwardly rectifying, potassium (GIRK) channels are important regulators of cellular excitability throughout the body. GIRK channels are heterotetrameric and homotetrameric combinations of the Kir3.1-4 (GIRK1-4) subunits. Different subunit combinations are expressed throughout the central nervous system (CNS) and the periphery, and most of these combinations contain a GIRK1 subunit. For example, the predominance of GIRK channels in the CNS are composed of GIRK1 and GIRK2 subunits, while the GIRK channels in cardiac atrial myocytes are made up mostly of GIRK1 and GIRK4 subunits. Although the vast majority of GIRK channels contain a GIRK1 subunit, discrete populations of cells that express non-GIRK1-containing GIRK (non-GIRK1/X) channels do exist. For instance, dopaminergic neurons in the ventral tegmental area of the brain, associated with addiction and reward, do not express the GIRK1 subunit. Targeting these non-GIRK1/X channels with subunit-selective pharmacological probes could lead to important insights into how GIRK channels are involved in reward and addiction. Such insights may, in turn, reveal therapeutic opportunities for the treatment or prevention of addiction. Previously, our laboratory discovered small molecules that can specifically modulate the activity of GIRK1-containing GIRK channels. However, efforts to generate compounds active on non-GIRK1/X channels from these scaffolds have been unsuccessful. Recently, ivermectin was shown to modulate non-GIRK1/X channels, and historically, ivermectin is known to modulate a wide variety of neuronal channels and receptors. Further, ivermectin is a complex natural product, which makes it a challenging starting point for development of more selective, effective, and potent compounds. Thus, while ivermectin provides proof-of-concept as a non-GIRK1/X channel activator, it is of limited utility. Therefore, we sought to discover a synthetic small molecule that would serve as a starting point for the development of non-GIRK1/X channel modulators. To accomplish this, we used a high-throughput thallium flux assay to screen a 100 000-compound library in search of activators of homomeric GIRK2 channels. Using this approach, we discovered VU0529331, the first synthetic small molecule reported to activate non-GIRK1/X channels, to our knowledge. This discovery represents the first step toward developing potent and selective non-GIRK1/X channel probes. Such molecules will help elucidate the role of GIRK channels in addiction, potentially establishing a foundation for future development of therapies utilizing targeted GIRK channel modulation.
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Affiliation(s)
- Krystian A. Kozek
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Medical Scientist Training Program, Vanderbilt University, Nashville, Tennessee, USA
| | - Yu Du
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Swagat Sharma
- Department of Pharmaceutical Sciences, Center for Drug Discovery, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - Francis J. Prael
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Brittany D. Spitznagel
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Sujay V. Kharade
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Jerod S. Denton
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, USA
| | - Corey R. Hopkins
- Department of Pharmaceutical Sciences, Center for Drug Discovery, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska, USA
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
- vanderbilt Institute of Chemical Biology, Vanderbilt University, Nashville, Tennessee, USA
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Palygin O, Pochynyuk O, Staruschenko A. Distal tubule basolateral potassium channels: cellular and molecular mechanisms of regulation. Curr Opin Nephrol Hypertens 2018; 27:373-378. [PMID: 29894319 PMCID: PMC6217967 DOI: 10.1097/mnh.0000000000000437] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
PURPOSE OF REVIEW Multiple clinical and translational evidence support benefits of high potassium diet; however, there many uncertainties underlying the molecular and cellular mechanisms determining effects of dietary potassium. Kir4.1 and Kir5.1 proteins form a functional heteromer (Kir4.1/Kir5.1), which is the primary inwardly rectifying potassium channel on the basolateral membrane of both distal convoluted tubule (DCT) and the collecting duct principal cells. The purpose of this mini-review is to summarize latest advances in our understanding of the evolution, physiological relevance and mechanisms controlling these channels. RECENT FINDINGS Kir4.1 and Kir5.1 channels play a critical role in determining electrolyte homeostasis in the kidney and blood pressure, respectively. It was reported that Kir4.1/Kir5.1 serves as potassium sensors in the distal nephron responding to variations in dietary intake and hormonal stimuli. Global and kidney specific knockouts of either channel resulted in hypokalemia and severe cardiorenal phenotypes. Furthermore, knock out of Kir5.1 in Dahl salt-sensitive rat background revealed the crucial role of the Kir4.1/Kir5.1 channel in salt-induced hypertension. SUMMARY Here, we focus on reviewing novel experimental evidence of the physiological function, expression and hormonal regulation of renal basolateral inwardly rectifying potassium channels. Further investigation of molecular and cellular mechanisms controlling Kir4.1 and Kir4.1/Kir5.1-mediating pathways and development of specific compounds targeting these channels function is essential for proper control of electrolyte homeostasis and blood pressure.
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Affiliation(s)
- Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226
| | - Oleh Pochynyuk
- Department of Integrative Biology, University of Texas Health Science Center, Houston, TX 77030
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Kharade SV, Kurata H, Bender AM, Blobaum AL, Figueroa EE, Duran A, Kramer M, Days E, Vinson P, Flores D, Satlin LM, Meiler J, Weaver CD, Lindsley CW, Hopkins CR, Denton JS. Discovery, Characterization, and Effects on Renal Fluid and Electrolyte Excretion of the Kir4.1 Potassium Channel Pore Blocker, VU0134992. Mol Pharmacol 2018; 94:926-937. [PMID: 29895592 DOI: 10.1124/mol.118.112359] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 05/30/2018] [Indexed: 12/28/2022] Open
Abstract
The inward rectifier potassium (Kir) channel Kir4.1 (KCNJ10) carries out important physiologic roles in epithelial cells of the kidney, astrocytes in the central nervous system, and stria vascularis of the inner ear. Loss-of-function mutations in KCNJ10 lead to EAST/SeSAME syndrome, which is characterized by epilepsy, ataxia, renal salt wasting, and sensorineural deafness. Although genetic approaches have been indispensable for establishing the importance of Kir4.1 in the normal function of these tissues, the availability of pharmacological tools for acutely manipulating the activity of Kir4.1 in genetically normal animals has been lacking. We therefore carried out a high-throughput screen of 76,575 compounds from the Vanderbilt Institute of Chemical Biology library for small-molecule modulators of Kir4.1. The most potent inhibitor identified was 2-(2-bromo-4-isopropylphenoxy)-N-(2,2,6,6-tetramethylpiperidin-4-yl)acetamide (VU0134992). In whole-cell patch-clamp electrophysiology experiments, VU0134992 inhibits Kir4.1 with an IC50 value of 0.97 µM and is 9-fold selective for homomeric Kir4.1 over Kir4.1/5.1 concatemeric channels (IC50 = 9 µM) at -120 mV. In thallium (Tl+) flux assays, VU0134992 is greater than 30-fold selective for Kir4.1 over Kir1.1, Kir2.1, and Kir2.2; is weakly active toward Kir2.3, Kir6.2/SUR1, and Kir7.1; and is equally active toward Kir3.1/3.2, Kir3.1/3.4, and Kir4.2. This potency and selectivity profile is superior to Kir4.1 inhibitors amitriptyline, nortriptyline, and fluoxetine. Medicinal chemistry identified components of VU0134992 that are critical for inhibiting Kir4.1. Patch-clamp electrophysiology, molecular modeling, and site-directed mutagenesis identified pore-lining glutamate 158 and isoleucine 159 as critical residues for block of the channel. VU0134992 displayed a large free unbound fraction (fu) in rat plasma (fu = 0.213). Consistent with the known role of Kir4.1 in renal function, oral dosing of VU0134992 led to a dose-dependent diuresis, natriuresis, and kaliuresis in rats. Thus, VU0134992 represents the first in vivo active tool compound for probing the therapeutic potential of Kir4.1 as a novel diuretic target for the treatment of hypertension.
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Affiliation(s)
- Sujay V Kharade
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Haruto Kurata
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Aaron M Bender
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Anna L Blobaum
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Eric E Figueroa
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Amanda Duran
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Meghan Kramer
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Emily Days
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Paige Vinson
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Daniel Flores
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Lisa M Satlin
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jens Meiler
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - C David Weaver
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Craig W Lindsley
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Corey R Hopkins
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, Tennessee (S.V.K., M.K., J.S.D.); Center for Neuroscience Drug Discovery and the Vanderbilt Specialized Chemistry Center for Accelerated Probe Development (H.K., A.M.B., A.L.B., C.W.L., C.R.H.), Departments of Pharmacology (H.K., A.M.B., E.E.F., J.M., C.D.W., C.W.L., J.S.D.) and Chemistry (A.D., J.M., C.D.W., C.W.L.), High-Throughput Screening Center (E.D., P.V.), and Institute of Chemical Biology (C.D.W., C.W.L., J.S.D.), Vanderbilt University, Nashville, Tennessee; Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York (D.F., L.M.S.); and Department of Pharmaceutical Sciences, University of Nebraska Medical Center, Omaha, Nebraska (C.R.H.)
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Aréchiga-Figueroa IA, Marmolejo-Murillo LG, Cui M, Delgado-Ramírez M, van der Heyden MAG, Sánchez-Chapula JA, Rodríguez-Menchaca AA. High-potency block of Kir4.1 channels by pentamidine: Molecular basis. Eur J Pharmacol 2017; 815:56-63. [PMID: 28993158 DOI: 10.1016/j.ejphar.2017.10.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2017] [Revised: 10/03/2017] [Accepted: 10/05/2017] [Indexed: 02/06/2023]
Abstract
Inward rectifier potassium (Kir) channels are expressed in almost all mammalian tissues and contribute to a wide range of physiological processes. Kir4.1 channel expression is found in the brain, inner ear, eye, and kidney. Loss-of-function mutations in the pore-forming Kir4.1 subunit cause an autosomal recessive disorder characterized by epilepsy, ataxia, sensorineural deafness and tubulopathy (SeSAME/EST syndrome). Despite its importance in physiological and pathological conditions, pharmacological research of Kir4.1 is limited. Here, we characterized the effect of pentamidine on Kir4.1 channels using electrophysiology, mutagenesis and computational methods. Pentamidine potently inhibited Kir4.1 channels when applied to the cytoplasmic side under inside-out patch clamp configuration (IC50 = 97nM). The block was voltage dependent. Molecular modeling predicted the binding of pentamidine to the transmembrane pore region of Kir4.1 at aminoacids T127, T128 and E158. Mutation of each of these residues reduced the potency of pentamidine to block Kir4.1 channels. A pentamidine analog (PA-6) inhibited Kir4.1 with similar potency (IC50 = 132nM). Overall, this study shows that pentamidine blocks Kir4.1 channels interacting with threonine and glutamate residues in the transmembrane pore region. These results can be useful to design novel compounds with major potency and specificity over Kir4.1 channels.
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Affiliation(s)
- Iván A Aréchiga-Figueroa
- CONACYT, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, San Luis Potosí, SLP, Mexico
| | | | - Meng Cui
- Department of Pharmaceutical Sciences, Northeastern University, Boston, MA, USA
| | - Mayra Delgado-Ramírez
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, SLP, Mexico
| | - Marcel A G van der Heyden
- Department of Medical Physiology, Division Heart & Lungs, University Medical Center Utrecht, Utrecht, The Netherlands
| | - José A Sánchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Col, Mexico
| | - Aldo A Rodríguez-Menchaca
- Departamento de Fisiología y Biofísica, Facultad de Medicina, Universidad Autónoma de San Luis Potosí, SLP, Mexico.
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12
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Dadi PK, Vierra NC, Days E, Dickerson MT, Vinson PN, Weaver CD, Jacobson DA. Selective Small Molecule Activators of TREK-2 Channels Stimulate Dorsal Root Ganglion c-Fiber Nociceptor Two-Pore-Domain Potassium Channel Currents and Limit Calcium Influx. ACS Chem Neurosci 2017; 8:558-568. [PMID: 27805811 PMCID: PMC5901755 DOI: 10.1021/acschemneuro.6b00301] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The two-pore-domain potassium (K2P) channel TREK-2 serves to modulate plasma membrane potential in dorsal root ganglia c-fiber nociceptors, which tunes electrical excitability and nociception. Thus, TREK-2 channels are considered a potential therapeutic target for treating pain; however, there are currently no selective pharmacological tools for TREK-2 channels. Here we report the identification of the first TREK-2 selective activators using a high-throughput fluorescence-based thallium (Tl+) flux screen (HTS). An initial pilot screen with a bioactive lipid library identified 11-deoxy prostaglandin F2α as a potent activator of TREK-2 channels (EC50 ≈ 0.294 μM), which was utilized to optimize the TREK-2 Tl+ flux assay (Z' = 0.752). A HTS was then performed with 76 575 structurally diverse small molecules. Many small molecules that selectively activate TREK-2 were discovered. As these molecules were able to activate single TREK-2 channels in excised membrane patches, they are likely direct TREK-2 activators. Furthermore, TREK-2 activators reduced primary dorsal root ganglion (DRG) c-fiber Ca2+ influx. Interestingly, some of the selective TREK-2 activators such as 11-deoxy prostaglandin F2α were found to inhibit the K2P channel TREK-1. Utilizing chimeric channels containing portions of TREK-1 and TREK-2, the region of the TREK channels that allows for either small molecule activation or inhibition was identified. This region lies within the second pore domain containing extracellular loop and is predicted to play an important role in modulating TREK channel activity. Moreover, the selective TREK-2 activators identified in this HTS provide important tools for assessing human TREK-2 channel function and investigating their therapeutic potential for treating chronic pain.
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Affiliation(s)
- Prasanna K. Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Nicholas C. Vierra
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Emily Days
- Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Matthew T. Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - Paige N. Vinson
- Department of Biochemistry, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, United States
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13
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Chloroquine blocks the Kir4.1 channels by an open-pore blocking mechanism. Eur J Pharmacol 2017; 800:40-47. [PMID: 28216048 DOI: 10.1016/j.ejphar.2017.02.024] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 02/03/2017] [Accepted: 02/15/2017] [Indexed: 11/23/2022]
Abstract
Kir4.1 channels have been implicated in various physiological processes, mainly in the K+ homeostasis of the central nervous system and in the control of glial function and neuronal excitability. Even though, pharmacological research of these channels is very limited. Chloroquine (CQ) is an amino quinolone derivative known to inhibit Kir2.1 and Kir6.2 channels with different action mechanism and binding site. Here, we employed patch-clamp methods, mutagenesis analysis, and molecular modeling to characterize the molecular pharmacology of Kir4.1 inhibition by CQ. We found that this drug inhibits Kir4.1 channels heterologously expressed in HEK-293 cells. CQ produced a fast-onset voltage-dependent pore-blocking effect on these channels. In inside-out patches, CQ showed notable higher potency (IC50 ≈0.5μM at +50mV) and faster onset of block when compared to whole-cell configuration (IC50 ≈7μM at +60mV). Also, CQ showed a voltage-dependent unblock with repolarization. These results suggest that the drug directly blocks Kir4.1 channels by a pore-plugging mechanism. Moreover, we found that two residues (Thr128 and Glu158), facing the central cavity and located within the transmembrane pore, are particularly important structural determinants of CQ block. This evidence was similar to what was previously reported with Kir6.2, but distinct from the interaction site (cytoplasmic pore) CQ-Kir2.1. Thus, our findings highlight the diversity of interaction sites and mechanisms that underlie amino quinolone inhibition of Kir channels.
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14
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Swale DR, Engers DW, Bollinger SR, Gross A, Inocente EA, Days E, Kanga F, Johnson RM, Yang L, Bloomquist JR, Hopkins CR, Piermarini PM, Denton JS. An insecticide resistance-breaking mosquitocide targeting inward rectifier potassium channels in vectors of Zika virus and malaria. Sci Rep 2016; 6:36954. [PMID: 27849039 PMCID: PMC5111108 DOI: 10.1038/srep36954] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 10/19/2016] [Indexed: 01/01/2023] Open
Abstract
Insecticide resistance is a growing threat to mosquito control programs around the world, thus creating the need to discover novel target sites and target-specific compounds for insecticide development. Emerging evidence suggests that mosquito inward rectifier potassium (Kir) channels represent viable molecular targets for developing insecticides with new mechanisms of action. Here we describe the discovery and characterization of VU041, a submicromolar-affinity inhibitor of Anopheles (An.) gambiae and Aedes (Ae.) aegypti Kir1 channels that incapacitates adult female mosquitoes from representative insecticide-susceptible and -resistant strains of An. gambiae (G3 and Akron, respectively) and Ae. aegypti (Liverpool and Puerto Rico, respectively) following topical application. VU041 is selective for mosquito Kir channels over several mammalian orthologs, with the exception of Kir2.1, and is not lethal to honey bees. Medicinal chemistry was used to develop an analog, termed VU730, which retains activity toward mosquito Kir1 but is not active against Kir2.1 or other mammalian Kir channels. Thus, VU041 and VU730 are promising chemical scaffolds for developing new classes of insecticides to combat insecticide-resistant mosquitoes and the transmission of mosquito-borne diseases, such as Zika virus, without harmful effects on humans and beneficial insects.
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Affiliation(s)
- Daniel R Swale
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Entomology, Louisiana State University Agricultural Center, Baton Rouge, LA, 70803, USA
| | - Darren W Engers
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Sean R Bollinger
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Aaron Gross
- Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA
| | - Edna Alfaro Inocente
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Emily Days
- Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Fariba Kanga
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Reed M Johnson
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Liu Yang
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Jeffrey R Bloomquist
- Department of Entomology and Nematology, University of Florida, Gainesville, FL 32610, USA
| | - Corey R Hopkins
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Center for Neuroscience Drug Discovery, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
| | - Peter M Piermarini
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691, USA
| | - Jerod S Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Department of Pharmacology, Vanderbilt University, Nashville, TN 37232, USA.,Vanderbilt Institute of Chemical Biology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.,Institute for Global Health, Vanderbilt University, Nashville, TN 37203, USA
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15
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Swale DR, Kurata H, Kharade SV, Sheehan J, Raphemot R, Voigtritter KR, Figueroa EE, Meiler J, Blobaum AL, Lindsley CW, Hopkins CR, Denton JS. ML418: The First Selective, Sub-Micromolar Pore Blocker of Kir7.1 Potassium Channels. ACS Chem Neurosci 2016; 7:1013-23. [PMID: 27184474 DOI: 10.1021/acschemneuro.6b00111] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The inward rectifier potassium (Kir) channel Kir7.1 (KCNJ13) has recently emerged as a key regulator of melanocortin signaling in the brain, electrolyte homeostasis in the eye, and uterine muscle contractility during pregnancy. The pharmacological tools available for exploring the physiology and therapeutic potential of Kir7.1 have been limited to relatively weak and nonselective small-molecule inhibitors. Here, we report the discovery in a fluorescence-based high-throughput screen of a novel Kir7.1 channel inhibitor, VU714. Site-directed mutagenesis of pore-lining amino acid residues identified glutamate 149 and alanine 150 as essential determinants of VU714 activity. Lead optimization with medicinal chemistry generated ML418, which exhibits sub-micromolar activity (IC50 = 310 nM) and superior selectivity over other Kir channels (at least 17-fold selective over Kir1.1, Kir2.1, Kir2.2, Kir2.3, Kir3.1/3.2, and Kir4.1) except for Kir6.2/SUR1 (equally potent). Evaluation in the EuroFins Lead Profiling panel of 64 GPCRs, ion-channels, and transporters for off-target activity of ML418 revealed a relatively clean ancillary pharmacology. While ML418 exhibited low CLHEP in human microsomes which could be modulated with lipophilicity adjustments, it showed high CLHEP in rat microsomes regardless of lipophilicity. A subsequent in vivo PK study of ML418 by intraperitoneal (IP) administration (30 mg/kg dosage) revealed a suitable PK profile (Cmax = 0.20 μM and Tmax = 3 h) and favorable CNS distribution (mouse brain/plasma Kp of 10.9 to support in vivo studies. ML418, which represents the current state-of-the-art in Kir7.1 inhibitors, should be useful for exploring the physiology of Kir7.1 in vitro and in vivo.
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Affiliation(s)
| | | | | | - Jonathan Sheehan
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
| | | | | | | | - Jens Meiler
- Department
of Chemistry, Vanderbilt University, Nashville, Tennessee 37232, United States
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16
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Crucial role of astrocytes in temporal lobe epilepsy. Neuroscience 2016; 323:157-69. [DOI: 10.1016/j.neuroscience.2014.12.047] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Revised: 12/25/2014] [Accepted: 12/30/2014] [Indexed: 11/30/2022]
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17
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Yue JF, Qiao GH, Liu N, Nan FJ, Gao ZB. Novel KCNQ2 channel activators discovered using fluorescence-based and automated patch-clamp-based high-throughput screening techniques. Acta Pharmacol Sin 2016; 37:105-10. [PMID: 26725738 DOI: 10.1038/aps.2015.142] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Accepted: 11/12/2015] [Indexed: 11/09/2022] Open
Abstract
AIM To establish an improved, high-throughput screening techniques for identifying novel KCNQ2 channel activators. METHODS KCNQ2 channels were stably expressed in CHO cells (KCNQ2 cells). Thallium flux assay was used for primary screening, and 384-well automated patch-clamp IonWorks Barracuda was used for hit validation. Two validated activators were characterized using a conventional patch-clamp recording technique. RESULTS From a collection of 80 000 compounds, the primary screening revealed a total of 565 compounds that potentiated the fluorescence signals in thallium flux assay by more than 150%. When the 565 hits were examined in IonWorks Barracuda, 38 compounds significantly enhanced the outward currents recorded in KCNQ2 cells, and were confirmed as KCNQ2 activators. In the conventional patch-clamp recordings, two validated activators ZG1732 and ZG2083 enhanced KCNQ2 currents with EC50 values of 1.04±0.18 μmol/L and 1.37±0.06 μmol/L, respectively. CONCLUSION The combination of thallium flux assay and IonWorks Barracuda assay is an efficient high-throughput screening (HTS) route for discovering KCNQ2 activators.
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18
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Weller J, Steinhäuser C, Seifert G. pH-Sensitive K+ Currents and Properties of K2P Channels in Murine Hippocampal Astrocytes. ION CHANNELS AS THERAPEUTIC TARGETS, PART A 2016; 103:263-94. [DOI: 10.1016/bs.apcsb.2015.10.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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19
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High throughput screening technologies for ion channels. Acta Pharmacol Sin 2016; 37:34-43. [PMID: 26657056 DOI: 10.1038/aps.2015.108] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 10/12/2015] [Indexed: 11/08/2022] Open
Abstract
Ion channels are involved in a variety of fundamental physiological processes, and their malfunction causes numerous human diseases. Therefore, ion channels represent a class of attractive drug targets and a class of important off-targets for in vitro pharmacological profiling. In the past decades, the rapid progress in developing functional assays and instrumentation has enabled high throughput screening (HTS) campaigns on an expanding list of channel types. Chronologically, HTS methods for ion channels include the ligand binding assay, flux-based assay, fluorescence-based assay, and automated electrophysiological assay. In this review we summarize the current HTS technologies for different ion channel classes and their applications.
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20
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Application of chemical biology in target identification and drug discovery. Arch Pharm Res 2015; 38:1642-50. [PMID: 26242900 DOI: 10.1007/s12272-015-0643-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 07/29/2015] [Indexed: 10/23/2022]
Abstract
Drug discovery and development is vital to the well-being of mankind and sustainability of the pharmaceutical industry. Using chemical biology approaches to discover drug leads has become a widely accepted path partially because of the completion of the Human Genome Project. Chemical biology mainly solves biological problems through searching previously unknown targets for pharmacologically active small molecules or finding ligands for well-defined drug targets. It is a powerful tool to study how these small molecules interact with their respective targets, as well as their roles in signal transduction, molecular recognition and cell functions. There have been an increasing number of new therapeutic targets being identified and subsequently validated as a result of advances in functional genomics, which in turn led to the discovery of numerous active small molecules via a variety of high-throughput screening initiatives. In this review, we highlight some applications of chemical biology in the context of drug discovery.
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21
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Imaging potassium-flux through individual electropores in droplet interface bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015. [PMID: 26210300 DOI: 10.1016/j.bbamem.2015.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Using total internal reflection fluorescence microscopy of droplet interface bilayers containing the potassium-sensitive fluorophore APG-4, we imaged the ionic flux through individual electropores. We are able to monitor up to 30 individual pores in parallel and show voltage dependent responses in fluorescence that corresponds to the measured ionic current. These experiments help quantify the scope and current limitations of optical single channel recordings of potassium flux. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale.
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22
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Wright PD, Kanumilli S, Tickle D, Cartland J, Bouloc N, Dale T, Tresize DJ, McCloskey C, McCavera S, Blanks AM, Kettleborough C, Jerman JC. A High-Throughput Electrophysiology Assay Identifies Inhibitors of the Inwardly Rectifying Potassium Channel Kir7.1. ACTA ACUST UNITED AC 2015; 20:739-47. [PMID: 25656238 DOI: 10.1177/1087057115569156] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Accepted: 12/31/2014] [Indexed: 11/17/2022]
Abstract
Kir7.1 is an inwardly rectifying potassium channel that has been implicated in controlling the resting membrane potential of the myometrium. Abnormal uterine activity in pregnancy plays an important role in postpartum hemorrhage, and novel therapies for this condition may lie in manipulation of membrane potential. This work presents an assay development and screening strategy for identifying novel inhibitors of Kir7.1. A cell-based automated patch-clamp electrophysiology assay was developed using the IonWorks Quattro (Molecular Devices, Sunnyvale, CA) system, and the iterative optimization is described. In total, 7087 compounds were tested, with a hit rate (>40% inhibition) of 3.09%. During screening, average Z' values of 0.63 ± 0.09 were observed. After chemistry triage, lead compounds were resynthesized and activity confirmed by IC50 determinations. The most potent compound identified (MRT00200769) gave rise to an IC50 of 1.3 µM at Kir7.1. Compounds were assessed for selectivity using the inwardly rectifying potassium channel Kir1.1 (ROMK) and hERG (human Ether-à-go-go Related Gene). Pharmacological characterization of known Kir7.1 inhibitors was also carried out and analogues of VU590 tested to assess selectivity at Kir7.1.
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Affiliation(s)
- Paul D Wright
- MRC Technology, Center for Therapeutics Discovery, London, UK
| | | | - David Tickle
- MRC Technology, Center for Therapeutics Discovery, London, UK
| | - Jamie Cartland
- MRC Technology, Center for Therapeutics Discovery, London, UK
| | - Nathalie Bouloc
- MRC Technology, Center for Therapeutics Discovery, London, UK
| | - Timothy Dale
- Essen BioScience Ltd, Welwyn Garden City, Hertfordshire, UK
| | | | - Conor McCloskey
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK
| | - Samantha McCavera
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK
| | - Andrew M Blanks
- Division of Reproductive Health, Warwick Medical School, Clinical Sciences Research Laboratory, Coventry, UK
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23
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Raphemot R, Rouhier MF, Swale DR, Days E, Weaver CD, Lovell KM, Konkel LC, Engers DW, Bollinger SF, Hopkins C, Piermarini PM, Denton JS. Discovery and characterization of a potent and selective inhibitor of Aedes aegypti inward rectifier potassium channels. PLoS One 2014; 9:e110772. [PMID: 25375326 PMCID: PMC4222822 DOI: 10.1371/journal.pone.0110772] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Accepted: 09/16/2014] [Indexed: 12/12/2022] Open
Abstract
Vector-borne diseases such as dengue fever and malaria, which are transmitted by infected female mosquitoes, affect nearly half of the world's population. The emergence of insecticide-resistant mosquito populations is reducing the effectiveness of conventional insecticides and threatening current vector control strategies, which has created an urgent need to identify new molecular targets against which novel classes of insecticides can be developed. We previously demonstrated that small molecule inhibitors of mammalian Kir channels represent promising chemicals for new mosquitocide development. In this study, high-throughput screening of approximately 30,000 chemically diverse small-molecules was employed to discover potent and selective inhibitors of Aedes aegypti Kir1 (AeKir1) channels heterologously expressed in HEK293 cells. Of 283 confirmed screening ‘hits’, the small-molecule inhibitor VU625 was selected for lead optimization and in vivo studies based on its potency and selectivity toward AeKir1, and tractability for medicinal chemistry. In patch clamp electrophysiology experiments of HEK293 cells, VU625 inhibits AeKir1 with an IC50 value of 96.8 nM, making VU625 the most potent inhibitor of AeKir1 described to date. Furthermore, electrophysiology experiments in Xenopus oocytes revealed that VU625 is a weak inhibitor of AeKir2B. Surprisingly, injection of VU625 failed to elicit significant effects on mosquito behavior, urine excretion, or survival. However, when co-injected with probenecid, VU625 inhibited the excretory capacity of mosquitoes and was toxic, suggesting that the compound is a substrate of organic anion and/or ATP-binding cassette (ABC) transporters. The dose-toxicity relationship of VU625 (when co-injected with probenecid) is biphasic, which is consistent with the molecule inhibiting both AeKir1 and AeKir2B with different potencies. This study demonstrates proof-of-concept that potent and highly selective inhibitors of mosquito Kir channels can be developed using conventional drug discovery approaches. Furthermore, it reinforces the notion that the physical and chemical properties that determine a compound's bioavailability in vivo will be critical in determining the efficacy of Kir channel inhibitors as insecticides.
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Affiliation(s)
- Rene Raphemot
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Matthew F. Rouhier
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States of America
| | - Daniel R. Swale
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America
| | - Emily Days
- Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - C. David Weaver
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
| | - Kimberly M. Lovell
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America
| | - Leah C. Konkel
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America
| | - Darren W. Engers
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America
| | - Sean F. Bollinger
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America
| | - Corey Hopkins
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Institute for Global Health, Vanderbilt University, Nashville, TN, United States of America
- Department of Chemistry, Vanderbilt University School of Medicine, Nashville TN, United States of America
| | - Peter M. Piermarini
- Department of Entomology, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH, United States of America
- * E-mail: (PMP); (JSD)
| | - Jerod S. Denton
- Department of Anesthesiology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- Department of Pharmacology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Institute of Chemical Biology, Vanderbilt University School of Medicine, Nashville, TN, United States of America
- Institute for Global Health, Vanderbilt University, Nashville, TN, United States of America
- * E-mail: (PMP); (JSD)
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24
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Bagriantsev SN, Chatelain FC, Clark KA, Alagem N, Reuveny E, Minor DL. Tethered protein display identifies a novel Kir3.2 (GIRK2) regulator from protein scaffold libraries. ACS Chem Neurosci 2014; 5:812-22. [PMID: 25028803 PMCID: PMC4176385 DOI: 10.1021/cn5000698] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
![]()
Use of randomized peptide libraries
to evolve molecules with new
functions provides a means for developing novel regulators of protein
activity. Despite the demonstrated power of such approaches for soluble
targets, application of this strategy to membrane systems, such as
ion channels, remains challenging. Here, we have combined libraries
of a tethered protein scaffold with functional selection in yeast
to develop a novel activator of the G-protein-coupled mammalian inwardly
rectifying potassium channel Kir3.2 (GIRK2). We show that the novel
regulator, denoted N5, increases Kir3.2 (GIRK2) basal activity by
inhibiting clearance of the channel from the cellular surface rather
than affecting the core biophysical properties of the channel. These
studies establish the tethered protein display strategy as a means
to create new channel modulators and highlight the power of approaches
that couple randomized libraries with direct selections for functional
effects. Our results further underscore the possibility for the development
of modulators that influence channel function by altering cell surface
expression densities rather than by direct action on channel biophysical
parameters. The use of tethered library selection strategies coupled
with functional selection bypasses the need for a purified target
and is likely to be applicable to a range of membrane protein systems.
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Affiliation(s)
| | | | | | - Noga Alagem
- Department
of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eitan Reuveny
- Department
of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Daniel L. Minor
- Physical
Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States
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25
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Druggability of the inward rectifier family: a hope for rare channelopathies? Future Med Chem 2014; 6:971-3. [PMID: 24547691 DOI: 10.4155/fmc.14.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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