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Pennington MW, Czerwinski A, Norton RS. Peptide therapeutics from venom: Current status and potential. Bioorg Med Chem 2017; 26:2738-2758. [PMID: 28988749 DOI: 10.1016/j.bmc.2017.09.029] [Citation(s) in RCA: 181] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 09/14/2017] [Accepted: 09/19/2017] [Indexed: 12/19/2022]
Abstract
Peptides are recognized as being highly selective, potent and relatively safe as potential therapeutics. Peptides isolated from the venom of different animals satisfy most of these criteria with the possible exception of safety, but when isolated as single compounds and used at appropriate concentrations, venom-derived peptides can become useful drugs. Although the number of venom-derived peptides that have successfully progressed to the clinic is currently limited, the prospects for venom-derived peptides look very optimistic. As proteomic and transcriptomic approaches continue to identify new sequences, the potential of venom-derived peptides to find applications as therapeutics, cosmetics and insecticides grows accordingly.
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Affiliation(s)
| | - Andrzej Czerwinski
- Peptides International, Inc., 11621 Electron Drive, Louisville, KY 40299, USA
| | - Raymond S Norton
- Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Monash University, Parkville, 3052, Australia
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2
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Zidar N, Žula A, Tomašič T, Rogers M, Kirby RW, Tytgat J, Peigneur S, Kikelj D, Ilaš J, Mašič LP. Clathrodin, hymenidin and oroidin, and their synthetic analogues as inhibitors of the voltage-gated potassium channels. Eur J Med Chem 2017; 139:232-241. [PMID: 28802123 DOI: 10.1016/j.ejmech.2017.08.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 08/03/2017] [Accepted: 08/04/2017] [Indexed: 11/25/2022]
Abstract
We have prepared three alkaloids from the Agelas sponges, clathrodin, hymenidin and oroidin, and a series of their synthetic analogues, and evaluated their inhibitory effect against six isoforms of the Kv1 subfamily of voltage-gated potassium channels, Kv1.1-Kv1.6, expressed in Chinese Hamster ovary (CHO) cells using automated patch clamp electrophysiology assay. The most potent inhibitor was the (E)-N-(3-(2-amino-1H-imidazol-4-yl)allyl)-4,5-dichloro-1H-pyrrole-2-carboxamide (6g) with IC50 values between 1.4 and 6.1 μM against Kv1.3, Kv1.4, Kv1.5 and Kv1.6 channels. All compounds tested displayed selectivity against Kv1.1 and Kv1.2 channels. For confirmation of their activity and selectivity, compounds were additionally evaluated in the second independent system against Kv1.1-Kv1.6 and Kv10.1 channels expressed in Xenopus laevis oocytes under voltage clamp conditions where IC50 values against Kv1.3-Kv1.6 channels for the most active analogues (e.g. 6g) were lower than 1 μM. Because of the observed low sub-micromolar IC50 values and fairly low molecular weights, the prepared compounds represent good starting points for further optimisation towards more potent and selective voltage-gated potassium channel inhibitors.
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Affiliation(s)
- Nace Zidar
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia
| | - Aleš Žula
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia
| | - Tihomir Tomašič
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia
| | - Marc Rogers
- Xention Limited, Iconix Park, London Road, Pampisford, Cambridge CB22 3EG, UK
| | - Robert W Kirby
- Xention Limited, Iconix Park, London Road, Pampisford, Cambridge CB22 3EG, UK
| | - Jan Tytgat
- University of Leuven (KU Leuven), Toxicology & Pharmacology, O&N2, PO Box 922, Herestraat 49, 3000 Leuven, Belgium
| | - Steve Peigneur
- University of Leuven (KU Leuven), Toxicology & Pharmacology, O&N2, PO Box 922, Herestraat 49, 3000 Leuven, Belgium
| | - Danijel Kikelj
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia
| | - Janez Ilaš
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia.
| | - Lucija Peterlin Mašič
- University of Ljubljana, Faculty of Pharmacy, Aškerčeva cesta 7, 1000 Ljubljana, Slovenia.
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Shen B, Cao Z, Li W, Sabatier JM, Wu Y. Treating autoimmune disorders with venom-derived peptides. Expert Opin Biol Ther 2017; 17:1065-1075. [DOI: 10.1080/14712598.2017.1346606] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Bingzheng Shen
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
- Department of Pharmacy, Renmin Hospital, Wuhan University, Wuhan, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
| | | | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, China
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Valverde P, Kawai T, Taubman MA. Potassium Channel-blockers as Therapeutic Agents to Interfere with Bone Resorption of Periodontal Disease. J Dent Res 2016; 84:488-99. [PMID: 15914584 DOI: 10.1177/154405910508400603] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Inflammatory lesions of periodontal disease contain all the cellular components, including abundant activated/memory T- and B-cells, necessary to control immunological interactive networks and to accelerate bone resorption by RANKL-dependent and -independent mechanisms. Blockade of RANKL function has been shown to ameliorate periodontal bone resorption and other osteopenic disorders without affecting inflammation. Development of therapies aimed at decreasing the expression of RANKL and pro-inflammatory cytokines by T-cells constitutes a promising strategy to ameliorate not only bone resorption, but also inflammation. Several reports have demonstrated that the potassium channels Kv1.3 and IKCa1, through the use of selective blockers, play important roles in T-cell-mediated events, including T-cell proliferation and the production of pro-inflammatory cytokines. More recently, a potassium channel-blocker for Kv1.3 has been shown to down-regulate bone resorption by decreasing the ratio of RANKL-to-OPG expression by memory-activated T-cells. In this article, we first summarize the mechanisms by which chronically activated/memory T-cells, in concert with B-cells and macrophages, trigger inflammatory bone resorption. Then, we describe the main structural and functional characteristics of potassium channels Kv1.3 and IKCa1 in some of the cells implicated in periodontal disease progression. Finally, this review elucidates some recent advances in the use of potassium channel-blockers of Kv1.3 and IKCa1 to ameliorate the clinical signs or side-effects of several immunological disorders and to decrease inflammatory bone resorption in periodontal disease. ABBREVIATIONS: AICD, activation-induced cell death; APC, antigen-presenting cells; B(K), large conductance; CRAC, calcium release-activated calcium channels; DC, dendritic cell; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; IFN-γ, interferon-γ; IP3, inositol (1,4,5)-triphosphate; (K)ir, inward rectifier; JNK, c-Jun N-terminal kinase; I(K), intermediate conductance; LPS, lipopolysaccharide; L, ligand; MCSF, macrophage colony-stimulating factor; MHC, major histocompatibility complex; NFAT, nuclear factor of activated T-cells; RANK, receptor activator of nuclear factor-κB; TCM, central memory T-cells; TEM, effector memory T-cells; TNF, tumor necrosis factor; TRAIL, TNF-related apoptosis-inducing ligand; OPG, osteoprotegerin; Omp29, 29-kDa outer membrane protein; PKC, protein kinase C; PLC, phospholipase C; RT-PCR, reverse-transcriptase polymerase chain-reaction; S(K), small conductance; TCR, T-cell receptor; and (K)v, voltage-gated.
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Affiliation(s)
- P Valverde
- Tufts University School of Dental Medicine, One Kneeland Street, Boston, MA 02111, USA.
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Jorgensen C, Darré L, Oakes V, Torella R, Pryde D, Domene C. Lateral Fenestrations in K(+)-Channels Explored Using Molecular Dynamics Simulations. Mol Pharm 2016; 13:2263-73. [PMID: 27173896 DOI: 10.1021/acs.molpharmaceut.5b00942] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Potassium channels are of paramount physiological and pathological importance and therefore constitute significant drug targets. One of the keys to rationalize the way drugs modulate ion channels is to understand the ability of such small molecules to access their respective binding sites, from which they can exert an activating or inhibitory effect. Many computational studies have probed the energetics of ion permeation, and the mechanisms of voltage gating, but little is known about the role of fenestrations as possible mediators of drug entry in potassium channels. To explore the existence, structure, and conformational dynamics of transmembrane fenestrations accessible by drugs in potassium channels, molecular dynamics simulation trajectories were analyzed from three potassium channels: the open state voltage-gated channel Kv1.2, the G protein-gated inward rectifying channel GIRK2 (Kir3.2), and the human two-pore domain TWIK-1 (K2P1.1). The main results of this work were the identification of the sequence identity of four main lateral fenestrations of similar length and with bottleneck radius in the range of 0.9-2.4 Å for this set of potassium channels. It was found that the fenestrations in Kv1.2 and Kir3.2 remain closed to the passage of molecules larger than water. In contrast, in the TWIK-1 channel, both open and closed fenestrations are sampled throughout the simulation, with bottleneck radius shown to correlate with the random entry of lipid membrane molecules into the aperture of the fenestrations. Druggability scoring function analysis of the fenestration regions suggests that Kv and Kir channels studied are not druggable in practice due to steric constraining of the fenestration bottleneck. A high (>50%) fenestration sequence identity was found in each potassium channel subfamily studied, Kv1, Kir3, and K2P1. Finally, the reported fenestration sequence of TWIK-1 compared favorably with another channel, K2P channel TREK-2, reported to possess open fenestrations, suggesting that K2P channels could be druggable via fenestrations, for which we reported atomistic detail of the fenestration region, including the flexible residues M260 and L264 that interact with POPC membrane in a concerted fashion with the aperture and closure of the fenestrations.
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Affiliation(s)
- Christian Jorgensen
- Department of Chemistry, King's College London , Britannia House, 7 Trinity Street, London SE1 1DB, U.K
| | - Leonardo Darré
- Department of Chemistry, King's College London , Britannia House, 7 Trinity Street, London SE1 1DB, U.K
| | - Victoria Oakes
- Department of Chemistry, King's College London , Britannia House, 7 Trinity Street, London SE1 1DB, U.K
| | - Rubben Torella
- Pfizer Neuroscience and Pain Research Unit, Worldwide Medicinal Chemistry , Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, U.K
| | - David Pryde
- Pfizer Neuroscience and Pain Research Unit, Worldwide Medicinal Chemistry , Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, U.K
| | - Carmen Domene
- Department of Chemistry, King's College London , Britannia House, 7 Trinity Street, London SE1 1DB, U.K.,Chemistry Research Laboratory, University of Oxford , Mansfield Road, Oxford OX1 3TA, U.K
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Jorgensen C, Darré L, Vanommeslaeghe K, Omoto K, Pryde D, Domene C. In silico identification of PAP-1 binding sites in the Kv1.2 potassium channel. Mol Pharm 2015; 12:1299-307. [PMID: 25734225 DOI: 10.1021/acs.molpharmaceut.5b00023] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Voltage-gated potassium channels of the Kv1 family play a crucial role in the generation and transmission of electrical signals in excitable cells affecting neuronal and cardiac activities. Small-molecule blockage of these channels has been proposed to occur via a cooperative mechanism involving two main blocking sites: the inner-pore site located below the selectivity filter, and a side-pocket cavity located between the pore and the voltage sensor. Using 0.5 μs molecular dynamics simulation trajectories complemented by docking calculations, the potential binding sites of the PAP-1 (5-(4-phenoxybutoxy)psoralen) blocker to the crystal structure of Kv1.2 channel have been studied. The presence of both mentioned blocking sites at Kv1.2 is confirmed, adding evidence in favor of a cooperative channel blockage mechanism. These observations provide insight into drug modulation that will guide further developments of Kv inhibitors.
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Affiliation(s)
- Christian Jorgensen
- †Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London SE1 1DB, U.K
| | - Leonardo Darré
- †Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London SE1 1DB, U.K
| | - Kenno Vanommeslaeghe
- ‡Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, 20 Penn Street, Baltimore, Maryland 21201, United States
| | - Kiyoyuki Omoto
- §Worldwide Medicinal Chemistry, Pfizer Neusentis, Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, U.K
| | - David Pryde
- §Worldwide Medicinal Chemistry, Pfizer Neusentis, Portway Building, Granta Park, Great Abington, Cambridge CB21 6GS, U.K
| | - Carmen Domene
- †Department of Chemistry, Britannia House, 7 Trinity Street, King's College London, London SE1 1DB, U.K.,∥Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, U.K
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Abstract
A recent patent application from Bionomics/Merck Serono describes novel compounds as blockers of the voltage-gated Kv1.3 ion channel. The blockade of this channel shows great promise as a new therapeutic target for the treatment of autoimmune disorders such as multiple sclerosis, psoriasis, diabetes and rheumatoid arthritis. The generic claim of this patent refers to a new chemotype of Kv1.3 blockers based on an amide core with potent IC50's which are potentially within the nanomolar range. This article briefly reviews the chemistry and biology found in the patent and compares it with previous discoveries in the field.
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Affiliation(s)
- William Nguyen
- The Scripps Research Institute, Department of Molecular Therapeutics , 130 Scripps Way, Jupiter, FL , USA +1 561 228 2210 ; +1 561 228 3092 ;
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8
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Shan WG, Zhang LW, Xiang JG, Zhan ZJ. Natural Friedelanes. Chem Biodivers 2013; 10:1392-434. [DOI: 10.1002/cbdv.201100256] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Indexed: 01/09/2023]
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Hautz T, Krapf C, Grahammer J, Zelger B, Hickethier T, Seger C, Eberhart N, Wallner C, Messner F, Kotsch K, Griesmacher A, Brandacher G, Lee WPA, Margreiter R, Pratschke J, Glossmann H, Schneeberger S. Targeting the Kv1.3 potassium channel for immunosuppression in vascularized composite allotransplantation - a pilot study. Transpl Int 2013; 26:552-61. [PMID: 23489391 DOI: 10.1111/tri.12080] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 03/19/2012] [Accepted: 02/04/2013] [Indexed: 12/19/2022]
Abstract
Kv1.3-channels are critically involved in activation and function of effector memory T cells. Blocking Kv1.3-channels was investigated for its effect on skin rejection in a rat limb-transplantation-model. Animals received the Kv1.3-blocker correolide C systemically or locally as intra-graft-treatment in combination with tacrolimus. Systemic (intraperitoneal) administration of correolide C resulted in slight, but significant prolongation of allograft survival compared with untreated and placebo treated controls. In 4/6 correolide C treated animals, histology showed an intact epidermis and a mild infiltrate by day 10. High correolide C plasma trough levels correlated with prolonged allograft survival. A decrease in CD4+ and CD8+ effector memory T cells was observed in allograft skin, peripheral blood and the spleen on day 5. When applied subcutaneously in combination with systemic tacrolimus (30 days+/-anti-lymphocyte serum) detectable, but insignificant prolongation of graft survival was achieved. 2/5 animals showed an intact epidermis and a mild infiltrate until day 45. Tapering systemic tacrolimus and weaning on day 50 resulted in rejection by day 55, regardless of local correolide C treatment. Subcutaneous injection did not lead to systemic plasma levels. The Kv1.3-channel is a potential drug target worth exploring in more detail for immunosuppression in vascularized composite allotransplantation.
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Affiliation(s)
- Theresa Hautz
- Department of Visceral, Transplant and Thoracic Surgery, Center of Operative Medicine, Innsbruck Medical University, Innsbruck, Austria
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Xiao R, Pang Y, Li QW. The buccal gland of Lampetra japonica is a source of diverse bioactive proteins. Biochimie 2012; 94:1075-9. [PMID: 22586701 DOI: 10.1016/j.biochi.2011.12.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Abstract
The parasitic phase lampreys (Lampetra japonica) are bloodsuckers in the marine, and their buccal gland secretion (lamphredin) contains various regulators such as anticoagulants, ion channel blockers, and immune suppressors like those from leeches, insects, ticks, vampire bats, and snakes. This review focuses on the functions and characteristics of the active proteins from the buccal gland of L. japonica for the first time, and provides new insights into the parasitic mechanisms of lampreys and the possibilities of developing drugs such as novel anticoagulants, thrombolytic agents, local anesthetics, and immunosuppressants.
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Affiliation(s)
- Rong Xiao
- School of Life Sciences, Liaoning Normal University, Dalian 116081, China
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Zhu J, Yan J, Thornhill WB. N-glycosylation promotes the cell surface expression of Kv1.3 potassium channels. FEBS J 2012; 279:2632-44. [PMID: 22613618 DOI: 10.1111/j.1742-4658.2012.08642.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The voltage-gated potassium channel Kv1.3 plays an essential role in modulating membrane excitability in many cell types. Kv1.3 is a heavily glycosylated membrane protein. Two successive N-glycosylation consensus sites, N228NS and N229ST, are present on the S1-S2 linker of rat Kv1.3. Our data suggest that Kv1.3 contains only one N-glycan and it is predominantly attached to N229 in the S1-S2 extracellular linker. Preventing N-glycosylation of Kv1.3 significantly decreased its surface protein level and surface conductance density level, which were ∼ 49% and ∼ 46% respectively of the level of wild type. Supplementation of N-acetylglucosamine (GlcNAc), l-fucose or N-acetylneuraminic acid to the culture medium promoted Kv1.3 surface protein expression, whereas supplementation of d-glucose, d-mannose or d-galactose did not. Among the three effective monosaccharides/derivatives, adding GlcNAc appeared to reduce sialic acid content and increase the degree of branching in the N-glycan of Kv1.3, suggesting that the N-glycan structure and composition had changed. Furthermore, the cell surface half-life of the Kv1.3 surface protein was increased upon GlcNAc supplementation, indicating that it had decreased internalization. The GlcNAc effect appears to apply mainly to membrane proteins containing complex type N-glycans. Thus, N-glycosylation promotes Kv1.3 cell surface expression; supplementation of GlcNAc increased Kv1.3 surface protein level and decreased its internalization, presumably by a combined effect of decreased branch size and increased branching of the N-glycan.
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Affiliation(s)
- Jing Zhu
- Department of Biological Sciences and Center for Cancer, Genetic Diseases and Gene Regulation, Fordham University, Bronx, NY, USA
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Lam J, Wulff H. The Lymphocyte Potassium Channels Kv1.3 and KCa3.1 as Targets for Immunosuppression. Drug Dev Res 2011; 72:573-584. [PMID: 22241939 PMCID: PMC3253536 DOI: 10.1002/ddr.20467] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The voltage-gated Kv1.3 and the calcium-activated KCa3.1 potassium channel modulate many calcium-dependent cellular processes in immune cells, including T-cell activation and proliferation, and have therefore been proposed as novel therapeutic targets for immunomodulation. Kv1.3 is highly expressed in CCR7(-) effector memory T cells and is emerging as a target for T-cell mediated diseases like multiple sclerosis, rheumatoid arthritis, type-1 diabetes mellitus, allergic contact dermatitis, and psoriasis. KCa3.1 in contrast is expressed in CCR7(+) naïve and central memory T cells, as well as in mast cells, macrophages, dedifferentiated vascular smooth muscle cells, fibroblasts, vascular endothelium, and airway epithelium. Given this expression pattern, KCa3.1 is a potential therapeutic target for conditions ranging from inflammatory bowel disease, multiple sclerosis, arthritis, and asthma to cardiovascular diseases like atherosclerosis and post-angioplasty restenosis. Results from animal studies have been supportive of the therapeutic potential of both Kv1.3 and KCa3.1 blockers and have also not shown any toxicities associated with pharmacological Kv1.3 and KCa3.1 blockade. To date, two compounds targeting Kv1.3 are in preclinical development but, so far, no Kv1.3 blocker has advanced into clinical trials. KCa3.1 blockers, on the other hand, have been evaluated in clinical trials for sickle cell anemia and exercise-induced asthma, but have so far not shown efficacy. However, the trial results support KCa3.1 as a safe therapeutic target, and will hopefully help enable clinical trials for other medical conditions that might benefit from KCa3.1 blockade.
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Affiliation(s)
- Jenny Lam
- Department of Pharmacology, University of California Davis, Davis, CA 95616, USA
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Chi V, Pennington MW, Norton RS, Tarcha EJ, Londono LM, Sims-Fahey B, Upadhyay SK, Lakey JT, Iadonato S, Wulff H, Beeton C, Chandy KG. Development of a sea anemone toxin as an immunomodulator for therapy of autoimmune diseases. Toxicon 2011; 59:529-46. [PMID: 21867724 DOI: 10.1016/j.toxicon.2011.07.016] [Citation(s) in RCA: 162] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Revised: 06/16/2011] [Accepted: 07/20/2011] [Indexed: 01/05/2023]
Abstract
Electrophysiological and pharmacological studies coupled with molecular identification have revealed a unique network of ion channels--Kv1.3, KCa3.1, CRAC (Orai1 + Stim1), TRPM7, Cl(swell)--in lymphocytes that initiates and maintains the calcium signaling cascade required for activation. The expression pattern of these channels changes during lymphocyte activation and differentiation, allowing the functional network to adapt during an immune response. The Kv1.3 channel is of interest because it plays a critical role in subsets of T and B lymphocytes implicated in autoimmune disorders. The ShK toxin from the sea anemone Stichodactyla helianthus is a potent blocker of Kv1.3. ShK-186, a synthetic analog of ShK, is being developed as a therapeutic for autoimmune diseases, and is scheduled to begin first-in-man phase-1 trials in 2011. This review describes the journey that has led to the development of ShK-186.
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Affiliation(s)
- Victor Chi
- Department of Physiology and Biophysics, UC Irvine, Irvine, CA 92697, USA
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14
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Wulff H. Spiro azepane-oxazolidinones as Kv1.3 potassium channel blockers: WO2010066840. Expert Opin Ther Pat 2010; 20:1759-65. [PMID: 20954790 DOI: 10.1517/13543776.2010.528392] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
This article evaluates a patent application from Solvay Pharmaceuticals, which claims spiro azepane-oxazolidinones as novel blockers of the voltage-gated potassium channel Kv1.3 for the treatment of diabetes, psoriasis, obesity, transplant rejection and T-cell mediated autoimmune diseases such as rheumatoid arthritis and MS. The patent describes a new chemotype of Kv1.3 blockers and thus illustrates the growing interest of the pharmaceutical industry in Kv1.3 as a target of immunosuppression and metabolic disorders. This article briefly summarizes the chemistry and biological data provided in the patent and then compares the new compounds to Kv1.3 blockers previously disclosed by both academia and pharmaceutical companies.
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Affiliation(s)
- Heike Wulff
- University of California, Department of Pharmacology, Davis, Davis, CA 95616, USA.
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15
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Cheong A, Li J, Sukumar P, Kumar B, Zeng F, Riches K, Munsch C, Wood IC, Porter KE, Beech DJ. Potent suppression of vascular smooth muscle cell migration and human neointimal hyperplasia by KV1.3 channel blockers. Cardiovasc Res 2010; 89:282-9. [PMID: 20884640 PMCID: PMC3020133 DOI: 10.1093/cvr/cvq305] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIM The aim of the study was to determine the potential for K(V)1 potassium channel blockers as inhibitors of human neoinitimal hyperplasia. METHODS AND RESULTS Blood vessels were obtained from patients or mice and studied in culture. Reverse transcriptase-polymerase chain reaction and immunocytochemistry were used to detect gene expression. Whole-cell patch-clamp, intracellular calcium measurement, cell migration assays, and organ culture were used to assess channel function. K(V)1.3 was unique among the K(V)1 channels in showing preserved and up-regulated expression when the vascular smooth muscle cells switched to the proliferating phenotype. There was strong expression in neointimal formations. Voltage-dependent potassium current in proliferating cells was sensitive to three different blockers of K(V)1.3 channels. Calcium entry was also inhibited. All three blockers reduced vascular smooth muscle cell migration and the effects were non-additive. One of the blockers (margatoxin) was highly potent, suppressing cell migration with an IC(50) of 85 pM. Two of the blockers were tested in organ-cultured human vein samples and both inhibited neointimal hyperplasia. CONCLUSION K(V)1.3 potassium channels are functional in proliferating mouse and human vascular smooth muscle cells and have positive effects on cell migration. Blockers of the channels may be useful as inhibitors of neointimal hyperplasia and other unwanted vascular remodelling events.
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Affiliation(s)
- Alex Cheong
- Multidisciplinary Cardiovascular Research Centre, University of Leeds, Leeds LS2 9JT, UK
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16
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The beneficial effect of blocking Kv1.3 in the psoriasiform SCID mouse model. J Invest Dermatol 2010; 131:118-24. [PMID: 20739949 DOI: 10.1038/jid.2010.245] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The Kv1.3 channel is important in the activation and function of effector memory T cells. Recently, specific blockers of the Kv1.3 channel have been developed as a potential therapeutic option for diverse autoimmune diseases. In psoriatic lesions, most lymphocytes are memory effector T cells. The aim of the present study was to detect the expression of Kv1.3 channels in these cells in psoriatic lesions as well as in human psoriasiform skin grafts using the severe combined immunodeficient (SCID) mouse model. Histological and immunohistochemical staining for Kv1.3 expression and various inflammatory markers was performed in sections obtained from six psoriatic patients and 18 beige-SCID mice with psoriasiform human skin grafts. Six grafted mice were treated with Stichodactyla helianthus neurotoxin (ShK), a known Kv1.3 blocker. The results showed an increased number of Kv1.3+ cells in the psoriatic skin as well as in the psoriasiform skin grafts as compared with normal skin and normal skin grafts. Injections of ShK showed a marked therapeutic effect in three of six psoriasiform skin grafts. A significantly decreased number of Kv1.3+ cells was observed in the responders compared with the control grafts. This pilot study, although performed in a small number of mice, reveals the possible beneficial effect of Kv1.3 blockers in psoriasis patients.
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Castle NA. Pharmacological modulation of voltage-gated potassium channels as a therapeutic strategy. Expert Opin Ther Pat 2010; 20:1471-503. [PMID: 20726689 DOI: 10.1517/13543776.2010.513384] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
IMPORTANCE OF THE FIELD The human genome encodes at least 40 distinct voltage-gated potassium channel subtypes, which vary in regional expression, pharmacological and biophysical properties. Voltage-dependent potassium (Kv) channels help orchestrate many of the physiological and pathophysiological processes that promote and sometimes hinder the healthy functioning of our bodies. AREAS COVERED IN THIS REVIEW This review summarizes patent and scientific literature reports from the past decade highlighting the opportunities that Kv channels offer for the development of new therapeutic interventions for a wide variety of disorders. WHAT THE READER WILL GAIN The reader will gain an insight from an analysis of the associations of different Kv family members with disease processes, summary and evaluation of the development of therapeutically relevant pharmacological modulators of these channels, particularly focusing on proprietary agents being developed. TAKE HOME MESSAGE Development of new drugs that target Kv channels continue to be of great interest but is proving to be challenging. Nevertheless, opportunities for Kv channel modulators to have an impact on a wide range of disorders in the future remain an exciting prospect.
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Kiernan M, Barrie A, Szkolar J, Mills T, Wareing M. Functional Evidence for Oxygen-Sensitive Voltage-Gated Potassium Channels in Human Placental Vasculature. Placenta 2010; 31:553-5. [DOI: 10.1016/j.placenta.2010.03.009] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2010] [Revised: 03/16/2010] [Accepted: 03/16/2010] [Indexed: 10/19/2022]
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19
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Varga Z, Hajdu P, Panyi G. Ion channels in T lymphocytes: An update on facts, mechanisms and therapeutic targeting in autoimmune diseases. Immunol Lett 2010; 130:19-25. [DOI: 10.1016/j.imlet.2009.12.015] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 12/08/2009] [Accepted: 12/10/2009] [Indexed: 12/31/2022]
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20
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Rangaraju S, Chi V, Pennington MW, Chandy KG. Kv1.3 potassium channels as a therapeutic target in multiple sclerosis. Expert Opin Ther Targets 2010; 13:909-24. [PMID: 19538097 DOI: 10.1517/14728220903018957] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
We discuss the potential use of inhibitors of Kv1.3 potassium channels in T lymphocytes as therapeutics for multiple sclerosis. Current treatment strategies target the immune system in a non-selective manner. The resulting general immunosuppression, toxic side-effects and increased risk of opportunistic infections create the need for more selective therapeutics. Autoreactive effector-memory T (T(EM)) cells, considered to be major mediators of autoimmunity, express large numbers of Kv1.3 channels. Selective blockers of Kv1.3 inhibit calcium signaling, cytokine production and proliferation of T(EM) cells in vitro, and T(EM) cell-motility in vivo. Kv1.3 blockers ameliorate disease in animal models of multiple sclerosis, rheumatoid arthritis, type 1 diabetes mellitus and contact dermatitis without compromising the protective immune response to acute infections. Kv1.3 blockers have a good safety profile in rodents and primates.
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Affiliation(s)
- Srikant Rangaraju
- University of California, Department of Physiology and Biophysics, Irvine, California 92697, USA
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21
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Abstract
For more than 25 years, it has been widely appreciated that Ca2+ influx is essential to trigger T-lymphocyte activation. Patch clamp analysis, molecular identification, and functional studies using blockers and genetic manipulation have shown that a unique contingent of ion channels orchestrates the initiation, intensity, and duration of the Ca2+ signal. Five distinct types of ion channels--Kv1.3, KCa3.1, Orai1+ stromal interacting molecule 1 (STIM1) [Ca2+-release activating Ca2+ (CRAC) channel], TRPM7, and Cl(swell)--comprise a network that performs functions vital for ongoing cellular homeostasis and for T-cell activation, offering potential targets for immunomodulation. Most recently, the roles of STIM1 and Orai1 have been revealed in triggering and forming the CRAC channel following T-cell receptor engagement. Kv1.3, KCa3.1, STIM1, and Orai1 have been found to cluster at the immunological synapse following contact with an antigen-presenting cell; we discuss how channels at the synapse might function to modulate local signaling. Immuno-imaging approaches are beginning to shed light on ion channel function in vivo. Importantly, the expression pattern of Ca2+ and K+ channels and hence the functional network can adapt depending upon the state of differentiation and activation, and this allows for different stages of an immune response to be targeted specifically.
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Affiliation(s)
- Michael D Cahalan
- Department of Physiology and Biophysics, and the Institute for Immunology, University of California, Irvine, Irvine, CA 92697-4561, USA.
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22
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Ren YR, Pan F, Parvez S, Fleig A, Chong CR, Xu J, Dang Y, Zhang J, Jiang H, Penner R, Liu JO. Clofazimine inhibits human Kv1.3 potassium channel by perturbing calcium oscillation in T lymphocytes. PLoS One 2008; 3:e4009. [PMID: 19104661 PMCID: PMC2602975 DOI: 10.1371/journal.pone.0004009] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2008] [Accepted: 11/08/2008] [Indexed: 01/03/2023] Open
Abstract
The Kv1.3 potassium channel plays an essential role in effector memory T cells and has been implicated in several important autoimmune diseases including multiple sclerosis, psoriasis and type 1 diabetes. A number of potent small molecule inhibitors of Kv1.3 channel have been reported, some of which were found to be effective in various animal models of autoimmune diseases. We report herein the identification of clofazimine, a known anti-mycobacterial drug, as a novel inhibitor of human Kv1.3. Clofazimine was initially identified as an inhibitor of intracellular T cell receptor-mediated signaling leading to the transcriptional activation of human interleukin-2 gene in T cells from a screen of the Johns Hopkins Drug Library. A systematic mechanistic deconvolution revealed that clofazimine selectively blocked the Kv1.3 channel activity, perturbing the oscillation frequency of the calcium-release activated calcium channel, which in turn led to the inhibition of the calcineurin-NFAT signaling pathway. These effects of clofazimine provide the first line of experimental evidence in support of a causal relationship between Kv1.3 and calcium oscillation in human T cells. Furthermore, clofazimine was found to be effective in blocking human T cell-mediated skin graft rejection in an animal model in vivo. Together, these results suggest that clofazimine is a promising immunomodulatory drug candidate for treating a variety of autoimmune disorders.
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Affiliation(s)
- Yunzhao R. Ren
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Program in Biochemistry, Cellular and Molecular Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Fan Pan
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Suhel Parvez
- Center for Biomedical Research at The Queen's Medical Center and John A. Burns School of Medicine at the University of Hawaii, Honolulu, Hawaii, United States of America
| | - Andrea Fleig
- Center for Biomedical Research at The Queen's Medical Center and John A. Burns School of Medicine at the University of Hawaii, Honolulu, Hawaii, United States of America
| | - Curtis R. Chong
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jing Xu
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yongjun Dang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Hongsi Jiang
- Department of Medicine, Feinberg School of Medicine, Northwestern University, Evanston, Illinois, United States of America
| | - Reinhold Penner
- Center for Biomedical Research at The Queen's Medical Center and John A. Burns School of Medicine at the University of Hawaii, Honolulu, Hawaii, United States of America
| | - Jun O. Liu
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Program in Biochemistry, Cellular and Molecular Biology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
- Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
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23
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Ratliff KS, Petrov A, Eiermann GJ, Deng Q, Green MD, Kaczorowski GJ, McManus OB, Herrington J. An automated electrophysiology serum shift assay for K(V) channels. Assay Drug Dev Technol 2008; 6:243-53. [PMID: 18471078 DOI: 10.1089/adt.2008.128] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The presence of serum in biological samples often negatively impacts the quality of in vitro assays. However, assays tolerant of serum are useful for assessing the in vivo availability of a small molecule for its target. Electrophysiology assays of ion channels are notoriously sensitive to serum because of their reliance on the interaction of the plasma membrane with a recording electrode. Here we investigate the tolerance of an automated electrophysiology assay for a voltage-gated potassium (K(V)) channel to serum and purified plasma proteins. The delayed rectifier channel, K(V)2.1, stably expressed in Chinese hamster ovary cells produces large, stable currents on the IonWorks Quattro platform (MDS Analytical Technologies, Sunnyvale, CA), making it an ideal test case. K(V)2.1 currents recorded on this platform are highly resistant to serum, allowing recordings in as high as 33% serum. Using a set of compounds related to the K(V) channel blocker, 4-phenyl-4-[3-(2-methoxyphenyl)-3-oxo-2-azaprop-1-yl]cyclohexanone, we show that shifts in compound potency with whole serum or isolated serum proteins can be reliably measured with this assay. Importantly, this assay is also relatively insensitive to plasma, allowing the creation of a bioassay for inhibitors of K(V)2.1 channel activity. Here we show that such a bioassay can quantify the levels of the gating modifier, guangxitoxin-1E, in plasma samples from mice dosed with the peptide. This study demonstrates the utility of using an automated electrophysiology platform for measuring serum shifts and for bioassays of ion channel modulators.
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Affiliation(s)
- Kevin S Ratliff
- Department of Ion Channels, Merck Research Laboratories, Rahway, NJ 07065-0900, USA
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24
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Wulff H, Zhorov BS. K+ channel modulators for the treatment of neurological disorders and autoimmune diseases. Chem Rev 2008; 108:1744-73. [PMID: 18476673 PMCID: PMC2714671 DOI: 10.1021/cr078234p] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA.
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25
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Han X, Kawai T, Taubman MA. Interference with immune-cell-mediated bone resorption in periodontal disease. Periodontol 2000 2007; 45:76-94. [PMID: 17850450 DOI: 10.1111/j.1600-0757.2007.00215.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Xiaozhe Han
- Department of Immunology, The Forsyth Institute, Harvard Medical School, Harvard School of Dental Medicine, Boston, MA, USA
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26
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Panyi G, Deutsch C. Probing the cavity of the slow inactivated conformation of shaker potassium channels. ACTA ACUST UNITED AC 2007; 129:403-18. [PMID: 17438120 PMCID: PMC2154382 DOI: 10.1085/jgp.200709758] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Slow inactivation involves a local rearrangement of the outer mouth of voltage-gated potassium channels, but nothing is known regarding rearrangements in the cavity between the activation gate and the selectivity filter. We now report that the cavity undergoes a conformational change in the slow-inactivated state. This change is manifest as altered accessibility of residues facing the aqueous cavity and as a marked decrease in the affinity of tetraethylammonium for its internal binding site. These findings have implications for global alterations of the channel during slow inactivation and putative coupling between activation and slow-inactivation gates.
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Affiliation(s)
- Gyorgy Panyi
- Department of Biophysics and Cell Biology, University of Debrecen, Debrecen, Hungary.
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27
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Azam P, Sankaranarayanan A, Homerick D, Griffey S, Wulff H. Targeting effector memory T cells with the small molecule Kv1.3 blocker PAP-1 suppresses allergic contact dermatitis. J Invest Dermatol 2007; 127:1419-29. [PMID: 17273162 PMCID: PMC1929164 DOI: 10.1038/sj.jid.5700717] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The voltage-gated potassium channel Kv1.3 has been recently identified as a molecular target that allows for selective pharmacological suppression of effector memory T (T(EM)) cells without affecting the function of naïve and central memory T cells. We here investigated whether PAP-1, a small molecule Kv1.3 blocker (EC50=2 nM), could suppress allergic contact dermatitis (ACD). In a rat model of ACD, we first confirmed that the infiltrating cells in the elicitation phase are indeed CD8+ CD45RC- memory T cells with high Kv1.3 expression. In accordance with its selective effect on T(EM) cells, PAP-1 did not impair sensitization, but potently suppressed oxazolone-induced inflammation by inhibiting the infiltration of CD8+ T cells and reducing the production of the inflammatory cytokines IFN-gamma, IL-2, and IL-17 when administered intraperitoneally or orally during the elicitation phase. PAP-1 was equally effective when applied topically, demonstrating that it effectively penetrates skin. We further show that PAP-1 is not a sensitizer or an irritant and exhibits no toxicity in a 28-day toxicity study. Based on these results we propose that PAP-1 could potentially be developed into a drug for the topical treatment of inflammatory skin diseases such as psoriasis.
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Affiliation(s)
- Philippe Azam
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
| | | | - Daniel Homerick
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
| | - Stephen Griffey
- Comparative Pathology Laboratory University of California, Davis, California, USA
| | - Heike Wulff
- Department of Medical Pharmacology and Toxicology, University of California, Davis, California, USA
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28
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Monte Carlo-energy minimization of correolide in the Kv1.3 channel: possible role of potassium ion in ligand-receptor interactions. BMC STRUCTURAL BIOLOGY 2007; 7:5. [PMID: 17261195 PMCID: PMC1796882 DOI: 10.1186/1472-6807-7-5] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/22/2006] [Accepted: 01/29/2007] [Indexed: 01/31/2023]
Abstract
BACKGROUND Correolide, a nortriterpene isolated from the Costa Rican tree Spachea correa, is a novel immunosuppressant, which blocks Kv1.3 channels in human T lymphocytes. Earlier mutational studies suggest that correolide binds in the channel pore. Correolide has several nucleophilic groups, but the pore-lining helices in Kv1.3 are predominantly hydrophobic raising questions about the nature of correolide-channel interactions. RESULTS We employed the method of Monte Carlo (MC) with energy minimization to search for optimal complexes of correolide in Kv1.2-based models of the open Kv1.3 with potassium binding sites 2/4 or 1/3/5 loaded with K+ ions. The energy was MC-minimized from many randomly generated starting positions and orientations of the ligand. In all the predicted low-energy complexes, oxygen atoms of correolide chelate a K+ ion. Correolide-sensing residues known from mutational analysis along with the ligand-bound K+ ion provide major contributions to the ligand-binding energy. Deficiency of K+ ions in the selectivity filter of C-type inactivated Kv1.3 would stabilize K+-bound correolide in the inner pore. CONCLUSION Our study explains the paradox that cationic and nucleophilic ligands bind to the same region in the inner pore of K+ channels and suggests that a K+ ion is an important determinant of the correolide receptor and possibly receptors of other nucleophilic blockers of the inner pore of K+ channels.
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Abstract
Multiple sclerosis is a chronic inflammatory autoimmune disease of the central nervous system characterized by demyelination and axonal damage that result in disabling neurological deficits. Here the authors explain the rationale for the use of inhibitors of the Kv1.3 K+ channel in immune cells as a therapy for multiple sclerosis and other autoimmune disorders.
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Affiliation(s)
- Christine Beeton
- Department of Physiology and Biophysics, Medical School, University of California, Irvine, 92697, USA
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30
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Watanabe K, Iwasaki K, Abe T, Inoue M, Ohkubo K, Suzuki T, Katoh T. Enantioselective Total Synthesis of (−)-Candelalide A, a Novel Blocker of the Voltage-Gated Potassium Channel Kv1.3 for an Immunosuppressive Agent. Org Lett 2005; 7:3745-8. [PMID: 16092865 DOI: 10.1021/ol051398c] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A convergent route to (-)-candelalide A involved the union of a trans-decalin portion (AB ring) and a gamma-pyrone moiety through the C16-C3' bond to assemble the whole carbon framework and subsequent formation of the dihydropyran ring (C ring) as the crucial steps. A strategic [2,3]-Wittig rearrangement was employed for establishing the stereogenic center at C9 and an exo-methylene function at C8 present in the decalin portion. [reaction: see text]
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Affiliation(s)
- Kazuhiro Watanabe
- Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
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31
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Abstract
Ion channels are membrane proteins that flicker open and shut to regulate the flow of ions down their electrochemical gradient across the membrane and consequently regulate cellular excitability. Every living cell expresses ion channels, as they are critical life-sustaining proteins. Ion channels are generally either activated by voltage or by ligand interaction. For each group of ion channels the channels' molecular biology and biophysics will be introduced and the pharmacology of that group of channels will be reviewed. The in vitro and in vivo literature will be reviewed and, for ion channel groups in which clinical trials have been conducted, the efficacy and therapeutic potential of the neuroprotective compounds will be reviewed. A large part of this article will deal with glutamate receptors, focusing specifically on N-methyl-D-aspartate (NMDA) receptors. Although the outcome of clinical trials for NMDA receptor antagonists as therapeutics for acute stroke is disappointing, the culmination of these failed trials was preceded by a decade of efforts to develop these agents. Sodium and calcium channel antagonists will be reviewed and the newly emerging efforts to develop therapeutics targeting potassium channels will be discussed. The future development of stroke therapeutics targeting ion channels will be discussed in the context of the failures of the last decade in hopes that this decade will yield successful stroke therapeutics.
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Affiliation(s)
- D L Small
- Institute or Biological Sciences, National Research Council of Canada, Building M-54, 1200 Montreal Road, Ottawa, Ontario, Canada K1A 0R6.
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32
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Bao J, Miao S, Kayser F, Kotliar AJ, Baker RK, Doss GA, Felix JP, Bugianesi RM, Slaughter RS, Kaczorowski GJ, Garcia ML, Ha SN, Castonguay L, Koo GC, Shah K, Springer MS, Staruch MJ, Parsons WH, Rupprecht KM. Potent Kv1.3 inhibitors from correolide-modification of the C18 position. Bioorg Med Chem Lett 2005; 15:447-51. [PMID: 15603971 DOI: 10.1016/j.bmcl.2004.10.058] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2004] [Revised: 10/15/2004] [Accepted: 10/18/2004] [Indexed: 11/28/2022]
Abstract
Kv1.3, the voltage-gated potassium channel in human T cells, represents a new target for treating immunosuppression and autoimmune diseases. Correolide (1), a pentacyclic natural product, is a potent and selective Kv1.3 channel blocker. Simplification of correolide via removal of its E-ring generates enone 4, whose modification produced a new series of tetracyclic Kv1.3 blockers. The structure-activity relationship for this class of compounds in two functional assays, Rb_Kv and human T cell proliferation, is presented herein. The most potent analog 43 is 15-fold more potent than correolide as inhibitor of human T cell proliferation.
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Affiliation(s)
- Jianming Bao
- Department of Medicinal Chemistry, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA.
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Bruhova I, Zhorov BS. KvAP-based model of the pore region of shaker potassium channel is consistent with cadmium- and ligand-binding experiments. Biophys J 2005; 89:1020-9. [PMID: 15908577 PMCID: PMC1366588 DOI: 10.1529/biophysj.105.062240] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Potassium channels play fundamental roles in excitable cells. X-ray structures of bacterial potassium channels show that the pore-lining inner helices obstruct the cytoplasmic entrance to the closed channel KcsA, but diverge in widely open channels MthK and KvAP, suggesting a gating-hinge role for a conserved Gly in the inner helix. A different location of the gating hinge and a narrower open pore were proposed for voltage-gated Shaker potassium channels that have the Pro-473-Val-Pro motif. Two major observations back the proposal: cadmium ions lock mutant Val-476-Cys in the open state by bridging Cys-476 and His-486 in adjacent helices, and cadmium blocks the locked-open double mutant Val-474-Cys/Val-476-Cys by binding to Cys-474 residues. Here we used molecular modeling to show that the open Shaker should be as wide as KvAP to accommodate an open-channel blocker, correolide. We further built KvAP-, MthK-, and KcsA-based models of the Shaker mutants and Monte-Carlo-minimized them with constraints Cys-476-Cd(2+)-His-486. The latter were consistent with the KvAP-based model, causing a small-bend N-terminal to the Pro-473-Val-Pro motif. The constraints significantly distorted the MthK-based structure, making it similar to KvAP. The KcsA structure resisted the constraints. Two Cd(2+) ions easily block the locked-open KvAP-based model at Cys-474 residues, whereas constraining a single cadmium ion to four Cys-474 caused large conformational changes and electrostatic imbalance. Although mutual disposition of the voltage-sensor and pore domains in the KvAP x-ray structure is currently disputed, our results suggest that the pore-region domain retains a nativelike conformation in the crystal.
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Affiliation(s)
- Iva Bruhova
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada
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34
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Beeton C, Pennington MW, Wulff H, Singh S, Nugent D, Crossley G, Khaytin I, Calabresi PA, Chen CY, Gutman GA, Chandy KG. Targeting effector memory T cells with a selective peptide inhibitor of Kv1.3 channels for therapy of autoimmune diseases. Mol Pharmacol 2005; 67:1369-81. [PMID: 15665253 PMCID: PMC4275123 DOI: 10.1124/mol.104.008193] [Citation(s) in RCA: 199] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The voltage-gated Kv1.3 K(+) channel is a novel target for immunomodulation of autoreactive effector memory T (T(EM)) cells that play a major role in the pathogenesis of autoimmune diseases. We describe the characterization of the novel peptide ShK(L5) that contains l-phosphotyrosine linked via a nine-atom hydrophilic linker to the N terminus of the ShK peptide from the sea anemone Stichodactyla helianthus. ShK(L5) is a highly specific Kv1.3 blocker that exhibits 100-fold selectivity for Kv1.3 (K(d) = 69 pM) over Kv1.1 and greater than 250-fold selectivity over all other channels tested. ShK(L5) suppresses the proliferation of human and rat T(EM) cells and inhibits interleukin-2 production at picomolar concentrations. Naive and central memory human T cells are initially 60-fold less sensitive than T(EM) cells to ShK(L5) and then become resistant to the peptide during activation by up-regulating the calcium-activated K(Ca)3.1 channel. ShK(L5) does not exhibit in vitro cytotoxicity on mammalian cell lines and is negative in the Ames test. It is stable in plasma and when administered once daily by subcutaneous injection (10 mug/kg) attains "steady state" blood levels of approximately 300 pM. This regimen does not cause cardiac toxicity assessed by continuous EKG monitoring and does not alter clinical chemistry and hematological parameters after 2-week therapy. ShK(L5) prevents and treats experimental autoimmune encephalomyelitis and suppresses delayed type hypersensitivity in rats. ShK(L5) might prove useful for therapy of autoimmune disorders.
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Affiliation(s)
- Christine Beeton
- Department of Physiology and Biophysics, 291 Irvine Hall, Medical School, University of California-Irvine, Irvine, CA 92697-4561, USA
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35
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Abstract
It is commonly accepted that cells require K(+) channels to proliferate. The role(s) of K(+) channels in the process is, however, poorly understood. Cloning of K(+) channel genes opened the possibility to approach this problem in a way more independent from pharmacological tools. Recent work shows that several identified K(+) channels are important in both physiological and pathological cell proliferation and open a promising pathway for novel targeted therapies.
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Affiliation(s)
- Luis A Pardo
- Max-Planck Institute for Experimental Medicine, 37075 Göttingen, Germany.
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36
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Wulff H, Knaus HG, Pennington M, Chandy KG. K+ channel expression during B cell differentiation: implications for immunomodulation and autoimmunity. THE JOURNAL OF IMMUNOLOGY 2004; 173:776-86. [PMID: 15240664 DOI: 10.4049/jimmunol.173.2.776] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Using whole-cell patch-clamp, fluorescence microscopy and flow cytometry, we demonstrate a switch in potassium channel expression during differentiation of human B cells from naive to memory cells. Naive and IgD(+)CD27(+) memory B cells express small numbers of the voltage-gated Kv1.3 and the Ca(2+)-activated intermediate-conductance IKCa1 channel when quiescent, and increase IKCa1 expression 45-fold upon activation with no change in Kv1.3 levels. In contrast, quiescent class-switched memory B cells express high levels of Kv1.3 ( approximately 2000 channels/cell) and maintain their Kv1.3(high) expression after activation. Consistent with their channel phenotypes, proliferation of naive and IgD(+)CD27(+) memory B cells is suppressed by the specific IKCa1 inhibitor TRAM-34 but not by the potent Kv1.3 blocker Stichodactyla helianthus toxin, whereas the proliferation of class-switched memory B cells is suppressed by Stichodactyla helianthus toxin but not TRAM-34. These changes parallel those reported for T cells. Therefore, specific Kv1.3 and IKCa1 inhibitors may have use in therapeutic manipulation of selective lymphocyte subsets in immunological disorders.
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Affiliation(s)
- Heike Wulff
- Department of Medical Pharmacology and Toxicology, University of California, Davis, CA 95616, USA.
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37
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Abstract
New immunosuppressants are consistently developed to treat autoimmune diseases and some of them might have implications in multiple sclerosis (MS). A new antiproliferative agent, pixantrone, an analogue of mitoxantrone (MX), has a much lower cardiotoxicity and exerts the same potent immunosuppressive effects in experimental allergic encephalomyelitis (EAE). A phase I trial in MS patients is planned in the next future. New monoclonal antibodies (mAb) and other biological constructs containing foreign proteins are developed but their potential immunogenicity is a considerable drawback to their long-term administration. In addition, their beneficial effects in MS are not evident so far. Small molecules targeting the voltage-gated Kv1.3K+ channel regulating CA2+ signaling in T lymphocytes, specifically target activated, pathogenic T cells. Already found effective in EAE, those agents would be easier to handle than T-cell vaccination. Two new immunosuppressants with a unique mechanism of action (FTY720 and Epomycine M) selectively impair autoreactive T-cell homing, without affecting the other components of the immune response. The potent protective effect of TRY720 has been demonstrated in EAE and a phase I trial in MS appears warranted. Finally, a new concept about immunosuppressive treatments in organ transplantation, "tolerogenic immunosuppression", may have potential in MS.
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Affiliation(s)
- R E Gonsette
- National Center for Multiple Sclerosis, Vanheylenstraat 16, Melsbroek B-1820, Belgium.
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Chandy KG, Wulff H, Beeton C, Pennington M, Gutman GA, Cahalan MD. K+ channels as targets for specific immunomodulation. Trends Pharmacol Sci 2004; 25:280-9. [PMID: 15120495 PMCID: PMC2749963 DOI: 10.1016/j.tips.2004.03.010] [Citation(s) in RCA: 351] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The voltage-gated Kv1.3 channel and the Ca(2+)-activated IKCa1 K(+) channel are expressed in T cells in a distinct pattern that depends on the state of lymphocyte activation and differentiation. The channel phenotype changes during the progression from the resting to the activated cell state and from naïve to effector memory cells, affording promise for specific immunomodulatory actions of K(+) channel blockers. In this article, we review the functional roles of these channels in both naïve cells and memory cells, describe the development of selective inhibitors of Kv1.3 and IKCa1 channels, and provide a rationale for the potential therapeutic use of these inhibitors in immunological disorders.
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Affiliation(s)
- K George Chandy
- Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.
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39
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Fountain SJ, Cheong A, Flemming R, Mair L, Sivaprasadarao A, Beech DJ. Functional up-regulation of KCNA gene family expression in murine mesenteric resistance artery smooth muscle. J Physiol 2004; 556:29-42. [PMID: 14742730 PMCID: PMC1664901 DOI: 10.1113/jphysiol.2003.058594] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
This study focused on the hypothesis that KCNA genes (which encode K(V)alpha1 voltage-gated K(+) channels) have enhanced functional expression in smooth muscle cells of a primary determinant of peripheral resistance - the small mesenteric artery. Real-time PCR methodology was developed to measure cell type-specific in situ gene expression. Profiles were determined for arterial myocyte expression of RNA species encoding K(V)alpha1 subunits as well as K(V)beta1, K(V)alpha2.1, K(V)gamma9.3, BK(Ca)alpha1 and BK(Ca)beta1. The seven major KCNA genes were expressed and more readily detected in endothelium-denuded mesenteric resistance artery compared with thoracic aorta; quantification revealed dramatic differential expression of one to two orders of magnitude. There was also four times more RNA encoding K(V)alpha2.1 but less or similar amounts encoding K(V)beta1, K(V)gamma9.3, BK(Ca)alpha1 and BK(Cabeta)1. Patch-clamp recordings from freshly isolated smooth muscle cells revealed dominant K(V)alpha1 K(+) current and current density twice as large in mesenteric cells. Therefore, we suggest the increased RNA production of the resistance artery impacts on physiological function, although there is quantitatively less K(+) current than might be expected. The mechanism conferring up-regulated expression of KCNA genes may be common to all the gene family and play a functional role in the physiological control of blood pressure.
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Affiliation(s)
- S J Fountain
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
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40
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Abstract
Human peripheral blood T lymphocytes possess two types of K(+) channels: the voltage-gated Kv1.3 and the calcium-activated IKCa1 channels. The use of peptidyl inhibitors of Kv1.3 and IKCa1 indicated that these channels are involved in the maintenance of membrane potential and that they play a crucial role in Ca(2+) signaling during T-cell activation. Thus, in vitro blockade of Kv1.3 and IKCa1 leads to inhibition of cytokine production and lymphocyte proliferation. These observations prompted several groups of investigators in academia and pharmaceutical companies to characterize the expression of Kv1.3 and IKCa1 in different subsets of human T lymphocytes and to evaluate their potential as novel targets for immunosuppression. Recent in vivo studies showed that chronically activated T lymphocytes involved in the pathogenesis of multiple sclerosis present unusually high expression of Kv1.3 channels and that the treatment with selective Kv1.3 inhibitors can either prevent or ameliorate the symptoms of the disease. In this model of multiple sclerosis, blockade of IKCa1 channels had no effect alone, but improved the response to Kv1.3 inhibitors. In addition, the expression of Kv1.3 and IKCa1 channels in human cells is very restricted, which makes them attractive targets for a more cell-specific and less harmful action than what is typically obtained with classical immunosuppressants. Studies using high-throughput toxin displacement, (86)Rb-efflux screening or membrane potential assays led to the identification of non-peptidyl small molecules with high affinity for Kv1.3 or IKCa1 channels. Analysis of structure-function relationships in Kv1.3 and IKCa1 channels helped define the binding sites for channel blockers, allowing the design of a new generation of small molecules with selectivity for either Kv1.3 or IKCa1, which could help the development of new drugs for safer treatment of auto-immune diseases.
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Affiliation(s)
- Rosane Vianna-Jorge
- Divisão de Farmacologia, Coordenação de Pesquisa, Instituto Nacional de Câncer, Rio de Janeiro, Brazil.
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41
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Valverde P, Kawai T, Taubman MA. Selective blockade of voltage-gated potassium channels reduces inflammatory bone resorption in experimental periodontal disease. J Bone Miner Res 2004; 19:155-64. [PMID: 14753747 DOI: 10.1359/jbmr.0301213] [Citation(s) in RCA: 81] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
UNLABELLED The effects of the potassium channel (Kv1.3) blocker kaliotoxin on T-cell-mediated periodontal bone resorption were examined in rats. Systemic administration of kaliotoxin abrogated the bone resorption in conjunction with decreased RANKL mRNA expression by T-cells in gingival tissue. This study suggests a plausible therapeutic approach for inflammatory bone resorption by targeting Kv1.3. INTRODUCTION Kv1.3 is a critical potassium channel to counterbalance calcium influx at T-cell receptor activation. It is not known if Kv1.3 also regulates RANKL expression by antigen-activated T-cells, and consequently affects in vivo bone resorption mediated by activated T-cells. MATERIALS AND METHODS Actinobacillus actinomycetemcomitans 29-kDa outer membrane protein-specific Th1-clone cells were used to evaluate the expression of Kv1.3 (using reverse transcriptase-polymerase chain reaction [RT-PCR] and Western blot analyses) and the effects of the potassium channel blocker kaliotoxin (0-100 nM) on T-cell activation parameters ([3H]thymidine incorporation assays and ELISA) and expression of RANKL and osteoprotegerin (OPG; flow cytometry, Western blot, and RT-PCR analyses). A rat periodontal disease model based on the adoptive transfer of activated 29-kDa outer membrane protein-specific Th1 clone cells was used to analyze the effects of kaliotoxin in T-cell-mediated alveolar bone resorption and RANKL and OPG mRNA expression by gingival T-cells. Stimulated 29-kDa outer membrane protein-specific Th1 clone cells were transferred intravenously on day 0 to all animals used in the study (n = 7 animals per group). Ten micrograms of kaliotoxin were injected subcutaneously twice per day on days 0, 1, 2, and 3, after adoptive transfer of the T-cells. The control group of rats was injected with saline as placebo on the same days as injections for the kaliotoxin-treated group. The MOCP-5 osteoclast precursor cell line was used in co-culture studies with fixed 29-kDa outer membrane protein-specific Th1-clone cells to measure T-cell-derived RANKL-mediated effects on osteoclastogenesis and resorption pit formation assays in vitro. Statistical significance was evaluated by Student's t-test. RESULTS Kaliotoxin decreased T-cell activation parameters of 29-kDa outer membrane protein-specific Th1 clone cells in vitro and in vivo. Most importantly, kaliotoxin administration resulted in an 84% decrease of the bone resorption induced in the saline-treated control group. T-cells recovered from the gingival tissue of kaliotoxin-treated rats displayed lower ratios of RANKL and OPG mRNA expression than those recovered from the control group. The ratio of RANKL and osteoprotegerin protein expression and induction of RANKL-dependent osteoclastogenesis by the activated T-cells were also markedly decreased after kaliotoxin treatments in vitro. CONCLUSION The use of kaliotoxin or other means to block Kv1.3 may constitute a potential intervention therapy to prevent alveolar bone loss in periodontal disease.
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Affiliation(s)
- Paloma Valverde
- Department of Oral and Developmental Biology, Harvard Medical School and Harvard School of Dental Medicine, Boston, Massachusetts, USA.
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42
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Abstract
Venomous animals have evolved a vast array of peptide toxins for prey capture and defence. These peptides are directed against a wide variety of pharmacological targets, making them an invaluable source of ligands for studying the properties of these targets in different experimental paradigms. A number of these peptides have been used in vivo for proof-of-concept studies, with several having undergone preclinical or clinical development for the treatment of pain, diabetes, multiple sclerosis and cardiovascular diseases. Here we survey the pharmacology of venom peptides and assess their therapeutic prospects.
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Affiliation(s)
- Richard J Lewis
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia 4072, Australia.
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43
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Grunnet M, Rasmussen HB, Hay-Schmidt A, Klaerke DA. The voltage-gated potassium channel subunit, Kv1.3, is expressed in epithelia. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2003; 1616:85-94. [PMID: 14507422 DOI: 10.1016/s0005-2736(03)00198-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Shaker-type voltage-gated potassium channel, Kv1.3, is believed to be restricted in distribution to lymphocytes and neurons. In lymphocytes, this channel has gained intense attention since it has been proven that inhibition of Kv1.3 channels compromise T lymphocyte activation. To investigate possible expression of Kv1.3 channels in other types of tissue, such as epithelia, binding experiments, immunoprecipitation studies and immunohistochemical studies were performed. The double-mutated, radiolabeled peptidyl ligand, (125)I-HgTX(1)-A19Y/Y37F, which selectively binds Kv1.1, Kv1.2, Kv1.3 and Kv1.6 channels, was used to perform binding studies in epithelia isolated from rabbit kidney and colon. The equilibrium dissociation constant for this ligand was found to be in the sub-picomolar range and the maximal receptor concentration (in fM/mg protein) 1.68 for colon and 0.61-0.75 for kidney epithelium. To determine the subtype of Kv1 channels, immunoprecipitation studies with (125)I-HgTX(1)-A19Y/Y37F labeled epithelial membranes were performed with specific antibodies against Kv1.1, Kv1.2, Kv1.3, Kv1.4 or Kv1.6 subunits. These studies demonstrated that Kv1.3 subunits constituted more than 50% of the entire Kv1 subunit population. The precise localization of Kv1.3 subunits in epithelia was determined by immunohistochemical studies.
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Affiliation(s)
- Morten Grunnet
- Department of Medical Physiology, The Panum Institute, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen, Denmark
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44
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Wulff H, Calabresi PA, Allie R, Yun S, Pennington M, Beeton C, Chandy KG. The voltage-gated Kv1.3 K(+) channel in effector memory T cells as new target for MS. J Clin Invest 2003; 111:1703-13. [PMID: 12782673 PMCID: PMC156104 DOI: 10.1172/jci16921] [Citation(s) in RCA: 338] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Through a combination of fluorescence microscopy and patch-clamp analysis we have identified a striking alteration in K(+) channel expression in terminally differentiated human CCR7(-)CD45RA(-) effector memory T lymphocytes (T(EM)). Following activation, T(EM) cells expressed significantly higher levels of the voltage-gated K(+) channel Kv1.3 and lower levels of the calcium-activated K(+) channel IKCa1 than naive and central memory T cells (T(CM)). Upon repeated in vitro antigenic stimulation, naive cells differentiated into Kv1.3(high)IKCa1(low) T(EM) cells, and the potent Kv1.3-blocking sea anemone Stichodactyla helianthus peptide (ShK) suppressed proliferation of T(EM) cells without affecting naive or T(CM) lymphocytes. Thus, the Kv1.3(high)IKCa1(low) phenotype is a functional marker of activated T(EM) lymphocytes. Activated myelin-reactive T cells from patients with MS exhibited the Kv1.3(high)IKCa1(low) T(EM) phenotype, suggesting that they have undergone repeated stimulation during the course of disease; these cells may contribute to disease pathogenesis due to their ability to home to inflamed tissues and exhibit immediate effector function. The Kv1.3(high)IKCa1(low) phenotype was not seen in glutamic acid decarboxylase, insulin-peptide or ovalbumin-specific and mitogen-activated T cells from MS patients, or in myelin-specific T cells from healthy controls. Selective targeting of Kv1.3 in T(EM) cells may therefore hold therapeutic promise for MS and other T cell-mediated autoimmune diseases.
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Affiliation(s)
- Heike Wulff
- Department of Physiology and Biophysics, University of California Irvine, College of Medicine, Irvine, California 92697, USA
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45
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Miao S, Bao J, Garcia ML, Goulet JL, Hong XJ, Kaczorowski GJ, Kayser F, Koo GC, Kotliar A, Schmalhofer WA, Shah K, Sinclair PJ, Slaughter RS, Springer MS, Staruch MJ, Tsou NN, Wong F, Parsons WH, Rupprecht KM. Benzamide derivatives as blockers of Kv1.3 ion channel. Bioorg Med Chem Lett 2003; 13:1161-4. [PMID: 12643934 DOI: 10.1016/s0960-894x(03)00014-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The voltage-gated potassium channel, Kv1.3, is present in human T-lymphocytes. Blockade of Kv1.3 results in T-cell depolarization, inhibition of T-cell activation, and attenuation of immune responses in vivo. A class of benzamide Kv1.3 channel inhibitors has been identified. The structure-activity relationship within this class of compounds in two functional assays, Rb_Kv and T-cell proliferation, is presented. In in vitro assays, trans isomers display moderate selectivity for binding to Kv1.3 over other Kv1.x channels present in human brain.
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Affiliation(s)
- Shouwu Miao
- Department of Medicinal Chemistry, Merck Research Laboratories, PO Box 2000, Rahway, NJ 07065, USA.
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46
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Abstract
The voltage gated potassium channel (Kv1.3) has been shown to play a role in immune responsiveness. Blockade of the channel led to diminution of T cell activation and delayed type hypersensitivity. Previous in vitro studies of the blockade were focused on T cell activation and proliferation. In this study we examined other T and monocytic cell mediated events to glean the extent of the immunosuppressive effects of a Kv1.3 specific inhibitor, Margatoxin (MgTX). We found that MgTX inhibited the intracellular production of Th-1 as well as Th-2 cytokines. MgTX can also inhibit IL-2 production and proliferation of T cells upon stimulation with anti-CD3 and VCAM-1. Furthermore, a redirected cytolytic activity was also inhibited by MgTX. However, MgTX did not inhibit generation of CTL to EBV transformed lymphoma cells or antibody-dependent cellular cytolysis mediated by monocytes. It appears that a Kv1.3 blockade does not affect all immune responses, particularly those of innate immunity.
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Affiliation(s)
- Kashmira Shah
- Merck Research Laboratories, 80W-107, PO Box 2000, Rahway, NJ 07065, USA
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47
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Manikkam M, Li Y, Mitchell BM, Mason DE, Freeman LC. Potassium channel antagonists influence porcine granulosa cell proliferation, differentiation, and apoptosis. Biol Reprod 2002; 67:88-98. [PMID: 12080003 DOI: 10.1095/biolreprod67.1.88] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
This investigation determined the effects of K(+) channel antagonists on proliferation, differentiation, and apoptosis of porcine granulosa cells. The drugs screened for functional effects included the class III antiarrhythmic agents MK-499 and clofilium, the chromanol I(Ks) antagonist 293B, the benzodiazepine I(Ks) antagonists L-735,821 and L-768,673, and the peptidyl toxins charybdotoxin (CTX) and margatoxin (MTX). Granulosa cell proliferation and differentiation were assessed by serial measurements of cell number and progesterone accumulation in the culture media, respectively. Granulosa cell apoptosis was evaluated using flow cytometry. Additional information about drug effects was obtained by immunoblotting to detect expression of proliferating cell nuclear antigen, p27(kip1) and the caspase-3 substrate poly(ADP-ribose) polymerase. The ERG channel antagonist MK-499 had no functional effects on cultured granulosa cells. However, the broad spectrum K(+) channel antagonist clofilium decreased, in a concentration-dependent fashion, the number of viable granulosa cells cultured, and these effects were associated with induction of apoptosis. All three I(Ks) antagonists (293B, L-735,821, and L-768,673) increased basal, but not FSH-enhanced progesterone accumulation on Day 1 after treatment without affecting the number of viable cells in culture, an effect that was blocked by pimozide. In contrast, CTX and MTX increased the number of viable cells in FSH-stimulated cultures on Day 3 after treatment without affecting progesterone output per cell. These data demonstrate that selective antagonism of granulosa cell K(+) channels with distinct molecular correlates, electrophysiological properties, and expression patterns can influence differential granulosa cell proliferation, steroidogenic capability, and apoptosis. Thus, K(+) channels may represent pharmacological targets for affecting Granulosa cell function and oocyte maturation, in vivo or in vitro.
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Affiliation(s)
- Mohan Manikkam
- Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, KS 66506-5802, USA
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48
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49
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Davies A, Batchelor T, Eardley I, Beech D. Potassium Channel K
V
α1 Subunit Expression And Function In Human Detrusor Muscle. J Urol 2002. [DOI: 10.1016/s0022-5347(05)65254-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- A.M. Davies
- From the School of Biomedical Sciences, University of Leeds and Department of Urology, St James’s Hospital, Leeds, United Kingdom
| | - T.J.P. Batchelor
- From the School of Biomedical Sciences, University of Leeds and Department of Urology, St James’s Hospital, Leeds, United Kingdom
| | - I. Eardley
- From the School of Biomedical Sciences, University of Leeds and Department of Urology, St James’s Hospital, Leeds, United Kingdom
| | - D.J. Beech
- From the School of Biomedical Sciences, University of Leeds and Department of Urology, St James’s Hospital, Leeds, United Kingdom
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50
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Abstract
K(+) channels play critical roles in a wide variety of physiological processes, including the regulation of heart rate, muscle contraction, neurotransmitter release, neuronal excitability, insulin secretion, epithelial electrolyte transport, cell volume regulation, and cell proliferation. As such, K(+) channels have been recognized as potential therapeutic drug targets for many years. Unfortunately, progress toward identifying selective K(+) channel modulators has been severely hampered by the need to use native currents and primary cells in the drug-screening process. Today, however, more than 80 K(+) channel and K(+) channel-related genes have been identified, and an understanding of the molecular composition of many important native K(+) currents has begun to emerge. The identification of these molecular K(+) channel drug targets should lead to the discovery of novel drug candidates. A summary of progress is presented.
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Affiliation(s)
- Alan Wickenden
- Icagen Inc., Suite 460, 4222 Emperor Boulevard, Durham, NC 27703, USA.
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