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Mesirca P, Chemin J, Barrère C, Torre E, Gallot L, Monteil A, Bidaud I, Diochot S, Lazdunski M, Soong TW, Barrère-Lemaire S, Mangoni ME, Nargeot J. Selective blockade of Ca v1.2 (α1C) versus Ca v1.3 (α1D) L-type calcium channels by the black mamba toxin calciseptine. Nat Commun 2024; 15:54. [PMID: 38167790 PMCID: PMC10762068 DOI: 10.1038/s41467-023-43502-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 11/10/2023] [Indexed: 01/05/2024] Open
Abstract
L-type voltage-gated calcium channels are involved in multiple physiological functions. Currently available antagonists do not discriminate between L-type channel isoforms. Importantly, no selective blocker is available to dissect the role of L-type isoforms Cav1.2 and Cav1.3 that are concomitantly co-expressed in the heart, neuroendocrine and neuronal cells. Here we show that calciseptine, a snake toxin purified from mamba venom, selectively blocks Cav1.2 -mediated L-type calcium currents (ICaL) at concentrations leaving Cav1.3-mediated ICaL unaffected in both native cardiac myocytes and HEK-293T cells expressing recombinant Cav1.2 and Cav1.3 channels. Functionally, calciseptine potently inhibits cardiac contraction without altering the pacemaker activity in sino-atrial node cells, underscoring differential roles of Cav1.2- and Cav1.3 in cardiac contractility and automaticity. In summary, calciseptine is a selective L-type Cav1.2 Ca2+ channel blocker and should be a valuable tool to dissect the role of these L-channel isoforms.
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Affiliation(s)
- Pietro Mesirca
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France.
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France.
| | - Jean Chemin
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Christian Barrère
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Eleonora Torre
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Laura Gallot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Arnaud Monteil
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Department of Physiology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Isabelle Bidaud
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Sylvie Diochot
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Université Côte d'Azur, CNRS, IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), FHU InovPain (Fédération Hospitalo-Universitaire "Innovative Solutions in Refractory Chronic Pain"), F-06560, Valbonne, France
| | - Michel Lazdunski
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
- Université Côte d'Azur, CNRS, IPMC (Institut de Pharmacologie Moléculaire et Cellulaire), FHU InovPain (Fédération Hospitalo-Universitaire "Innovative Solutions in Refractory Chronic Pain"), F-06560, Valbonne, France
| | - Tuck Wah Soong
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Stéphanie Barrère-Lemaire
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France
| | - Joël Nargeot
- Institut de Génomique Fonctionnelle, Université de Montpellier, CNRS, INSERM, 34094, Montpellier, France.
- Laboratory of Excellence Ion Channels, Science & Therapeutics, F-06560, Valbonne, France.
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2
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Gao S, Yao X, Chen J, Huang G, Fan X, Xue L, Li Z, Wu T, Zheng Y, Huang J, Jin X, Wang Y, Wang Z, Yu Y, Liu L, Pan X, Song C, Yan N. Structural basis for human Ca v1.2 inhibition by multiple drugs and the neurotoxin calciseptine. Cell 2023; 186:5363-5374.e16. [PMID: 37972591 DOI: 10.1016/j.cell.2023.10.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 03/16/2023] [Accepted: 10/04/2023] [Indexed: 11/19/2023]
Abstract
Cav1.2 channels play crucial roles in various neuronal and physiological processes. Here, we present cryo-EM structures of human Cav1.2, both in its apo form and in complex with several drugs, as well as the peptide neurotoxin calciseptine. Most structures, apo or bound to calciseptine, amlodipine, or a combination of amiodarone and sofosbuvir, exhibit a consistent inactivated conformation with a sealed gate, three up voltage-sensing domains (VSDs), and a down VSDII. Calciseptine sits on the shoulder of the pore domain, away from the permeation path. In contrast, when pinaverium bromide, an antispasmodic drug, is inserted into a cavity reminiscent of the IFM-binding site in Nav channels, a series of structural changes occur, including upward movement of VSDII coupled with dilation of the selectivity filter and its surrounding segments in repeat III. Meanwhile, S4-5III merges with S5III to become a single helix, resulting in a widened but still non-conductive intracellular gate.
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Affiliation(s)
- Shuai Gao
- Department of Urology, Zhongnan Hospital of Wuhan University, TaiKang Center for Life and Medical Sciences, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
| | - Xia Yao
- Department of Urology, Zhongnan Hospital of Wuhan University, TaiKang Center for Life and Medical Sciences, School of Pharmaceutical Sciences, Wuhan University, Wuhan 430071, China; Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Jiaofeng Chen
- Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Gaoxingyu Huang
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Institute of Biology, Westlake Institute for Advanced Study, Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Hangzhou, Zhejiang 310024, China
| | - Xiao Fan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Lingfeng Xue
- Center for Quantitative Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China
| | - Zhangqiang Li
- Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Tong Wu
- Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yupeng Zheng
- Tsinghua-Peking Center for Life Sciences, Ministry of Education Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Jian Huang
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | - Xueqin Jin
- Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Yan Wang
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA
| | - Zhifei Wang
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA
| | - Yong Yu
- Department of Biological Sciences, St. John's University, Queens, NY 11439, USA
| | - Lei Liu
- Tsinghua-Peking Center for Life Sciences, Ministry of Education Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Center for Synthetic and Systems Biology, Department of Chemistry, Tsinghua University, Beijing 100084, China
| | - Xiaojing Pan
- Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Shenzhen Medical Academy of Research and Translation, Shenzhen, Guangdong 518107, China
| | - Chen Song
- Center for Quantitative Biology, Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
| | - Nieng Yan
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA; Beijing Frontier Research Center for Biological Structures, Tsinghua-Peking Center for Life Sciences, State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China; Shenzhen Medical Academy of Research and Translation, Shenzhen, Guangdong 518107, China.
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V V, Achar RR, M.U H, N A, T YS, Kameshwar VH, Byrappa K, Ramadas D. Venom peptides - A comprehensive translational perspective in pain management. Curr Res Toxicol 2021; 2:329-340. [PMID: 34604795 PMCID: PMC8473576 DOI: 10.1016/j.crtox.2021.09.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/02/2021] [Accepted: 09/08/2021] [Indexed: 12/21/2022] Open
Abstract
Venom peptides have been evolving complex therapeutic interventions that potently and selectively modulate a range of targets such as ion channels, receptors, and signaling pathways of physiological processes making it potential therapeutic. Several venom peptides were deduced in vivo for clinical development targeting pain management, diabetes, cardiovascular diseases, antimicrobial activity. Several contributions have been detailed for a clear perspective for a better understanding of venomous animals, their venom, and their pharmacological effects. Here we unravel and summarize the recent advances in wide venom peptides across varieties of species for their therapeutics prospects.
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Affiliation(s)
- Vidya V
- K. S Hegde Medical Academy, NITTE (Deemed to be) University, Mangalore 575015, Karnataka, India
| | - Raghu Ram Achar
- Division of Biochemistry, School of Life Sciences, JSS Academy of Higher Education & Research, S.S. Nagar, Mysuru 570 015, Karnataka, India
| | - Himathi M.U
- Division of Biochemistry, School of Life Sciences, JSS Academy of Higher Education & Research, S.S. Nagar, Mysuru 570 015, Karnataka, India
| | - Akshita N
- Division of Biochemistry, School of Life Sciences, JSS Academy of Higher Education & Research, S.S. Nagar, Mysuru 570 015, Karnataka, India
| | - Yogish Somayaji T
- Department of Post Graduate Studies and Research in Biochemistry, St. Aloysius College (Autonomous), Mangalore 575003, Karnataka, India
| | - Vivek Hamse Kameshwar
- School of Natural Science, Adichunchanagiri University, B.G. Nagara-571448, Nangamangala, Mandya, India
- School of Natural Sciences, ACU-CRI, Adichunchanagiri University, BGSIT Campus, B.G. Nagara-571448, Nagamangala, Mandya, India
| | - K. Byrappa
- School of Natural Sciences, ACU-CRI, Adichunchanagiri University, BGSIT Campus, B.G. Nagara-571448, Nagamangala, Mandya, India
- Center for Material Science and Technology, Vijnana Bhavan, University of Mysore, Mysuru, Karnataka, India
| | - Dinesha Ramadas
- Adichunchanagiri Institute for Molecular Medicine, AIMS, Adichunchanagiri University, B.G. Nagara-571448, Nagamangala, Mandya, India
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Molecular analysis of ATP-sensitive K(+) channel subunits expressed in mouse portal vein. Vascul Pharmacol 2015; 75:29-39. [PMID: 26163942 DOI: 10.1016/j.vph.2015.06.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 06/16/2015] [Accepted: 06/29/2015] [Indexed: 11/23/2022]
Abstract
BACKGROUND Several combinations of inwardly rectifying K(+) channel 6.x family pore-forming (KIR6.x) subunits associated with sulphonylurea receptor (SUR.x) subunits have been detected among ATP-sensitive K(+) (KATP) channels. It remains to be established which of these is expressed in native vascular smooth muscle. METHODS Pharmacological and electrophysiological properties of KATP channels in mouse portal vein were investigated using tension measurements and patch-clamp techniques. Molecular biological analyses were also performed to investigate the structural properties of these channels. RESULTS Spontaneous contractions in mouse portal vein were reversibly reduced by pinacidil and MCC-134, and the pinacidil-induced relaxation was antagonized by glibenclamide and U-37883A. In cell-attached mode, pinacidil activated glibenclamide-sensitive K(+) channels with a conductance (35 pS) similar to that of KIR6.1. RT-PCR analysis revealed the expression of KIR6.1, KIR6.2 and SUR2B transcripts. Using real-time PCR methods, the quantitative expression of KIR6.1 was much greater than that of KIR6.2. Immunohistochemical studies indicated the presence of KIR6.1 and SUR2B proteins in the smooth muscle layers of mouse portal vein and in single smooth muscle cells dispersed from mouse portal vein. CONCLUSIONS The results indicate that native KATP channels in mouse portal vein are likely to be composed of a heterocomplex of KIR6.1 and SUR2B subunits.
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Allen A, Islamovic E, Kaur J, Gold S, Shah D, Smith TJ. The virally encoded killer proteins from Ustilago maydis. FUNGAL BIOL REV 2013. [DOI: 10.1016/j.fbr.2012.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Akizuki O, Inayoshi A, Kitayama T, Yao K, Shirakura S, Sasaki K, Kusaka H, Matsubara M. Blockade of T-type voltage-dependent Ca2+ channels by benidipine, a dihydropyridine calcium channel blocker, inhibits aldosterone production in human adrenocortical cell line NCI-H295R. Eur J Pharmacol 2008; 584:424-34. [PMID: 18331727 DOI: 10.1016/j.ejphar.2008.02.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Revised: 01/25/2008] [Accepted: 02/06/2008] [Indexed: 11/16/2022]
Abstract
Benidipine, a long-lasting dihydropyridine calcium channel blocker, is used for treatment of hypertension and angina. Benidipine exerts pleiotropic pharmacological features, such as renoprotective and cardioprotective effects. In pathophysiological conditions, the antidiuretic hormone aldosterone causes development of renal and cardiovascular diseases. In adrenal glomerulosa cells, aldosterone is produced in response to extracellular potassium, which is mainly mediated by T-type voltage-dependent Ca2+ channels. More recently, it has been demonstrated that benidipine inhibits T-type Ca2+ channels in addition to L-type Ca2+ channels. Therefore, effect of calcium channel blockers, including benidipine, on aldosterone production and T-type Ca2+ channels using human adrenocortical cell line NCI-H295R was investigated. Benidipine efficiently inhibited KCl-induced aldosterone production at low concentration (3 and 10 nM), with inhibitory activity more potent than other calcium channel blockers. Patch clamp analysis indicated that benidipine concentration-dependently inhibited T-type Ca2+ currents at 10, 100 and 1000 nM. As for examined calcium channel blockers, inhibitory activity for T-type Ca2+ currents was well correlated with aldosterone production. L-type specific calcium channel blockers calciseptine and nifedipine showed no effect in both assays. These results indicate that inhibition of T-type Ca2+ channels is responsible for inhibition of aldosterone production in NCI-H295R cells. Benidipine efficiently inhibited KCl-induced upregulation of 11-beta-hydroxylase mRNA and aldosterone synthase mRNA as well as KCl-induced Ca2+ influx, indicating it as the most likely inhibition mechanism. Benidipine partially inhibited angiotensin II-induced aldosterone production, plus showed additive effects when used in combination with the angiotensin II type I receptor blocker valsartan. Benidipine also partially inhibited angiotensin II-induced upregulation of the above mRNAs and Ca2+ influx inhibitory activities of benidipine for aldosterone production. T-type Ca2+ channels may contribute to additional benefits of this drug for treating renal and cardiovascular diseases, beyond its primary anti-hypertensive effects from blocking L-type Ca2+ channels.
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Affiliation(s)
- Osamu Akizuki
- Pharmaceutical Research Center, Kyowa Hakko Kogyo Co., Ltd., Shizuoka 411-8731, Japan
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7
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Zhu HL, Tomoda T, Aishima M, Ito Y, Teramoto N. The actions of azelnidipine, a dihydropyridine-derivative Ca antagonist, on voltage-dependent Ba2+ currents in guinea-pig vascular smooth muscle. Br J Pharmacol 2006; 149:786-96. [PMID: 17016499 PMCID: PMC2014663 DOI: 10.1038/sj.bjp.0706919] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
BACKGROUND AND PURPOSE Although azelnidipine is used clinically to treat hypertension its effects on its target cells, Ca2+ channels, in smooth muscle have not been elucidated. Therefore, its effects on spontaneous contractions and voltage-dependent L-type Ca2+ channels were investigated in guinea-pig portal vein. EXPERIMENTAL APPROACH The inhibitory potency of azelnidipine on spontaneous contractions in guinea-pig portal vein was compared with those of other dihydropyridine (DHP)-derived Ca antagonists (amlodipine and nifedipine) by recording tension. Also its effects on voltage-dependent nifedipine-sensitive inward Ba2+ currents (IBa) in smooth muscle cells dispersed from guinea-pig portal vein were investigated by use of a conventional whole-cell patch-clamp technique. KEY RESULTS Spontaneous contractions in guinea-pig portal vein were reduced by all of the Ca antagonists (azelnidipine, Ki = 153 nM; amlodipine, Ki = 16 nM; nifedipine, Ki = 7 nM). In the whole-cell experiments, azelnidipine inhibited the peak amplitude of IBa in a concentration- and voltage-dependent manner (-60 mV, Ki = 282 nM; -90 mV, Ki = 2 microM) and shifted the steady-state inactivation curve of IBa to the left at -90 mV by 16 mV. The inhibitory effects of azelnidipine on IBa persisted after 7 min washout at -60 mV. In contrast, IBa gradually recovered after being inhibited by amlodipine, but did not return to control levels. Both azelnidipine and amlodipine caused a resting block of IBa at -90 mV. Only nifedipine appeared to interact competitively with S(-)-Bay K 8644. CONCLUSIONS AND IMPLICATIONS These results suggest that azelnidipine induces long-lasting vascular relaxation by inhibiting voltage-dependent L-type Ca2+ channels in vascular smooth muscle.
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Affiliation(s)
- H-L Zhu
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - T Tomoda
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - M Aishima
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - Y Ito
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
| | - N Teramoto
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University Fukuoka, Japan
- Author for correspondence:
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8
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Abstract
Some of the most potent and specific inhibitors of voltage-gated calcium channels are peptide toxins that inhibit channel function not by occlusion of the channel pore, but rather by interfering with the voltage dependence and kinetics of channel opening and closing. Many such gating modifier toxins conform to the inhibitor cystine knot structural family and have primary sequence or functional mechanism similar to toxins that target voltage-gated sodium or potassium channels. This review introduces known gating modifiers of calcium channels, discusses the selectivity, binding sites, and mechanism of the toxin-channel interaction, and reviews the usefulness of these toxins as research tools and as the basis for novel calcium channel pharmacology and therapeutics.
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Affiliation(s)
- Stefan I McDonough
- Department of Neuroscience, Amgen, Inc., One Kendall Square Bldg 1000, Cambridge, MA 02139, USA
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9
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Andreasen D, Friis UG, Uhrenholt TR, Jensen BL, Skøtt O, Hansen PB. Coexpression of Voltage-Dependent Calcium Channels Ca
v
1.2, 2.1a, and 2.1b in Vascular Myocytes. Hypertension 2006; 47:735-41. [PMID: 16505211 DOI: 10.1161/01.hyp.0000203160.80972.47] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Voltage-dependent Ca2+ channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+ currents. The expression of both Cav2.1a (P-type) and Cav2.1b (Q-type) mRNA was demonstrated by RT-PCR in renal preglomerular vessels from rats and mice. Immunolabeling was performed on A7r5 cells, renal cryosections, and freshly isolated renal VSMCs with anti-Cav1.2 and anti-Cav2.1 antibodies. Conventional and confocal microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6+/-3.9% of the voltage-dependent Ca2+ current, and blocking P-type currents (omega-agatoxin IVA 10 nmol/L) led to 20.2+/-3.0% inhibition, whereas 300 nmol/L of omega agatoxin IVA (blocking P/Q-type) inhibited 45.0+/-7.3%. In rat aortic smooth muscle cells (A7r5), blockade of L-type channels resulted in 28.5+/-6.1% inhibition, simultaneous blockade of L-type and P-type channels inhibited 58.0+/-11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7+/-5.6%) of the Ca2+ current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+ channels in the rat and mouse.
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MESH Headings
- Animals
- Aorta/cytology
- Aorta/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, L-Type/physiology
- Calcium Channels, N-Type/genetics
- Calcium Channels, N-Type/metabolism
- Calcium Channels, N-Type/physiology
- Cell Line
- DNA, Recombinant
- Fluorescent Antibody Technique
- Genetic Variation
- Kidney/blood supply
- Male
- Mice
- Mice, Inbred C57BL
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/metabolism
- Patch-Clamp Techniques
- Protein Isoforms/genetics
- Protein Isoforms/metabolism
- Protein Isoforms/physiology
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
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Affiliation(s)
- Ditte Andreasen
- Physiology and Pharmacology, University of Southern Denmark, Odense, Denmark
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10
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Teramoto N, Tomoda T, Ito Y. Mefenamic acid as a novel activator of L-type voltage-dependent Ca2+ channels in smooth muscle cells from pig proximal urethra. Br J Pharmacol 2005; 144:919-25. [PMID: 15723098 PMCID: PMC1576071 DOI: 10.1038/sj.bjp.0706051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2004] [Accepted: 10/12/2004] [Indexed: 12/26/2022] Open
Abstract
The effects of mefenamic acid and Bay K 8644 on voltage-dependent nifedipine-sensitive inward Ba2+ currents in pig urethral myocytes were investigated by use of conventional whole-cell configuration patch clamp. Mefenamic acid increased the peak amplitude of voltage-dependent nifedipine-sensitive inward Ba2+ current without shifting the position of the current-voltage relationship. Mefenamic acid (300 microM) caused little shift in the activation curve although the voltage dependence of the steady-state inactivation was shifted to more positive potentials by 11 mV in the presence of mefenamic acid. Bay K 8644 (> or = 100 nM) enhanced voltage-dependent nifedipine-sensitive inward Ba2+ currents in a concentration- and voltage-dependent manner, shifting the maximum of the current-voltage relationship by 10 mV in the hyperpolarizing direction. Bay K 8644 (1 microM) significantly shifted the voltage dependence of the activation curve to more negative potentials by approximately 9 mV although Bay K 8644 caused little shift in the steady-state inactivation curve. These results indicate that mefenamic acid increased voltage-dependent nifedipine-sensitive inward Ba2+ currents through the activation of L-type Ca2+ channels with different kinetics from those of Bay K 8644 in pig urethral myocytes.
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Affiliation(s)
- Noriyoshi Teramoto
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi Ward, Fukuoka 812-8582, Japan.
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11
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Spelbrink RG, Dilmac N, Allen A, Smith TJ, Shah DM, Hockerman GH. Differential antifungal and calcium channel-blocking activity among structurally related plant defensins. PLANT PHYSIOLOGY 2004; 135:2055-67. [PMID: 15299136 PMCID: PMC520777 DOI: 10.1104/pp.104.040873] [Citation(s) in RCA: 151] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2004] [Revised: 05/12/2004] [Accepted: 05/13/2004] [Indexed: 05/18/2023]
Abstract
Plant defensins are a family of small Cys-rich antifungal proteins that play important roles in plant defense against invading fungi. Structures of several plant defensins share a Cys-stabilized alpha/beta-motif. Structural determinants in plant defensins that govern their antifungal activity and the mechanisms by which they inhibit fungal growth remain unclear. Alfalfa (Medicago sativa) seed defensin, MsDef1, strongly inhibits the growth of Fusarium graminearum in vitro, and its antifungal activity is markedly reduced in the presence of Ca(2+). By contrast, MtDef2 from Medicago truncatula, which shares 65% amino acid sequence identity with MsDef1, lacks antifungal activity against F. graminearum. Characterization of the in vitro antifungal activity of the chimeras containing portions of the MsDef1 and MtDef2 proteins shows that the major determinants of antifungal activity reside in the carboxy-terminal region (amino acids 31-45) of MsDef1. We further define the active site by demonstrating that the Arg at position 38 of MsDef1 is critical for its antifungal activity. Furthermore, we have found for the first time, to our knowledge, that MsDef1 blocks the mammalian L-type Ca(2+) channel in a manner akin to a virally encoded and structurally unrelated antifungal toxin KP4 from Ustilago maydis, whereas structurally similar MtDef2 and the radish (Raphanus sativus) seed defensin Rs-AFP2 fail to block the L-type Ca(2+) channel. From these results, we speculate that the two unrelated antifungal proteins, KP4 and MsDef1, have evolutionarily converged upon the same molecular target, whereas the two structurally related antifungal plant defensins, MtDef2 and Rs-AFP2, have diverged to attack different targets in fungi.
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Gage MJ, Rane SG, Hockerman GH, Smith TJ. The virally encoded fungal toxin KP4 specifically blocks L-type voltage-gated calcium channels. Mol Pharmacol 2002; 61:936-44. [PMID: 11901234 DOI: 10.1124/mol.61.4.936] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
KP4 is a virally encoded fungal toxin secreted by the P4 killer strain of Ustilago maydis. Previous studies demonstrated that this toxin inhibits growth of the target fungal cells by blocking calcium uptake rather than forming channels, as had been suggested previously. Unexpectedly, this toxin was also shown to inhibit voltage-gated calcium channel activity in mammalian cells. We used whole-cell patch-clamp techniques to further characterize this activity against mammalian cells. KP4 is shown to specifically block L-type calcium channels with weak voltage dependence to the block. Because KP4 activity is abrogated by calcium, KP4 probably binds competitively with calcium to the channel exterior. Finally, it is shown that chemical reagents that modify lysine residues reduce KP4 activity in both patch-clamp experiments on mammalian cells and in fungal killing assays. Because the only lysine residue is K42, this residue seems to be crucial for both mammalian and fungal channel activity. Our results defining the type of mammalian channel affected by this fungal toxin further support our contention that KP4 inhibits fungal growth by blocking transmembrane calcium flux through fungal calcium channels, and imply a high degree of structural homology between these fungal and mammalian calcium channels.
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Affiliation(s)
- Matthew J Gage
- Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA
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Teramoto N, Yunoki T, Ikawa S, Takano N, Tanaka K, Seki N, Naito S, Ito Y. The involvement of L-type Ca(2+) channels in the relaxant effects of the ATP-sensitive K(+) channel opener ZD6169 on pig urethral smooth muscle. Br J Pharmacol 2001; 134:1505-15. [PMID: 11724757 PMCID: PMC1573091 DOI: 10.1038/sj.bjp.0704408] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2001] [Revised: 07/24/2001] [Accepted: 09/24/2001] [Indexed: 11/08/2022] Open
Abstract
1. The effects of ZD6169, a novel ATP-sensitive K(+) channel (K(ATP) channel) opener, were investigated on membrane currents in isolated myocytes using patch-clamp techniques. Tension measurement was also performed to study the effects of ZD6169 on the resting tone of pig urethral smooth muscle. 2. Levcromakalim was more potent than ZD6169 in lowering the resting urethral tone. Relaxation induced by low concentrations of ZD6169 (< or =3 microM) was completely suppressed by additional application of glibenclamide (1 microM). In contrast, glibenclamide (1-10 microM) only partially inhibited the relaxation induced by higher concentrations of ZD6169 (> or = microM). 3. Bay K8644 (1 microM) reduced the maximum relaxation produced by ZD6169 (> or =10 microM). 4. In whole-cell configuration, ZD6169 suppressed the peak amplitude of voltage-dependent Ba(2+) currents in a concentration- and voltage-dependent manner, and at 100 microM, shifted the steady-state inactivation curve of the voltage-dependent Ba(2+) currents to the left at a holding potential of -90 mV. 5. In cell-attached configuration, open probability of unitary voltage-dependent Ba(2+) channels (27 pS, 90 mM Ba(2+)) was inhibited by 100 microM ZD6169 and by 10 microM nifedipine. 6. Reverse transcriptase-polymerase chain reaction (RT - PCR) analysis revealed the presence of the transcript of the alpha(1C) subunit of L-type Ca(2+) channels in pig urethra. 7. These results demonstrate that ZD6169 causes urethral relaxation through two distinct mechanisms, activation of K(ATP) channels at lower concentrations and inhibition of voltage-dependent Ca(2+) channels at higher concentrations (about 10 microM).
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Affiliation(s)
- N Teramoto
- Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan.
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Kotlikoff MI, Herrera G, Nelson MT. Calcium permeant ion channels in smooth muscle. Rev Physiol Biochem Pharmacol 1999; 134:147-99. [PMID: 10087909 DOI: 10.1007/3-540-64753-8_4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Affiliation(s)
- M I Kotlikoff
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Kuriyama H, Kitamura K, Itoh T, Inoue R. Physiological features of visceral smooth muscle cells, with special reference to receptors and ion channels. Physiol Rev 1998; 78:811-920. [PMID: 9674696 DOI: 10.1152/physrev.1998.78.3.811] [Citation(s) in RCA: 176] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Visceral smooth muscle cells (VSMC) play an essential role, through changes in their contraction-relaxation cycle, in the maintenance of homeostasis in biological systems. The features of these cells differ markedly by tissue and by species; moreover, there are often regional differences within a given tissue. The biophysical features used to investigate ion channels in VSMC have progressed from the original extracellular recording methods (large electrode, single or double sucrose gap methods), to the intracellular (microelectrode) recording method, and then to methods for recording from membrane fractions (patch-clamp, including cell-attached patch-clamp, methods). Remarkable advances are now being made thanks to the application of these more modern biophysical procedures and to the development of techniques in molecular biology. Even so, we still have much to learn about the physiological features of these channels and about their contribution to the activity of both cell and tissue. In this review, we take a detailed look at ion channels in VSMC and at receptor-operated ion channels in particular; we look at their interaction with the contraction-relaxation cycle in individual VSMC and especially at the way in which their activity is related to Ca2+ movements and Ca2+ homeostasis in the cell. In sections II and III, we discuss research findings mainly derived from the use of the microelectrode, although we also introduce work done using the patch-clamp procedure. These sections cover work on the electrical activity of VSMC membranes (sect. II) and on neuromuscular transmission (sect. III). In sections IV and V, we discuss work done, using the patch-clamp procedure, on individual ion channels (Na+, Ca2+, K+, and Cl-; sect. IV) and on various types of receptor-operated ion channels (with or without coupled GTP-binding proteins and voltage dependent and independent; sect. V). In sect. VI, we look at work done on the role of Ca2+ in VSMC using the patch-clamp procedure, biochemical procedures, measurements of Ca2+ transients, and Ca2+ sensitivity of contractile proteins of VSMC. We discuss the way in which Ca2+ mobilization occurs after membrane activation (Ca2+ influx and efflux through the surface membrane, Ca2+ release from and uptake into the sarcoplasmic reticulum, and dynamic changes in Ca2+ within the cytosol). In this article, we make only limited reference to vascular smooth muscle research, since we reviewed the features of ion channels in vascular tissues only recently.
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Affiliation(s)
- H Kuriyama
- Seinan Jogakuin University, Kokura-Kita, Fukuoka, Japan
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