1
|
Roston TM, Bezzerides VJ, Roberts JD, Abrams DJ. Management of ultrarare inherited arrhythmia syndromes. Heart Rhythm 2024:S1547-5271(24)03142-4. [PMID: 39154872 DOI: 10.1016/j.hrthm.2024.08.023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 08/06/2024] [Accepted: 08/08/2024] [Indexed: 08/20/2024]
Abstract
Ultrarare inherited arrhythmia syndromes are increasingly diagnosed as a result of increased awareness as well as increased availability and reduced cost of genetic testing. Yet by definition, their rarity and heterogeneous expression make development of evidence-based management strategies more challenging, typically employing strategies garnered from similar genetic cardiac disorders. For the most part, reliance on anecdotal experiences, expert opinion, and small retrospective cohort studies is the only means to diagnose and to treat these patients. Here we review the management of specific ultrarare inherited arrhythmic syndromes together with the genetic and molecular basis, which will become increasingly important with the development of targeted therapies to correct the biologic basis of these disorders.
Collapse
Affiliation(s)
- Thomas M Roston
- Division of Cardiology and Centre for Cardiovascular Innovation, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Vassilios J Bezzerides
- Center for Cardiovascular Genetics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts
| | - Jason D Roberts
- Population Health Research Institute, McMaster University, and Hamilton Health Sciences, Hamilton, Ontario, Canada
| | - Dominic J Abrams
- Center for Cardiovascular Genetics, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts.
| |
Collapse
|
2
|
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.
Collapse
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.
| |
Collapse
|
3
|
Allam S, Levenson-Palmer R, Chia Chang Z, Kaur S, Cernuda B, Raman A, Booth A, Dobbins S, Suppa G, Yang J, Buraei Z. Inactivation influences the extent of inhibition of voltage-gated Ca +2 channels by Gem-implications for channelopathies. Front Physiol 2023; 14:1155976. [PMID: 37654674 PMCID: PMC10466392 DOI: 10.3389/fphys.2023.1155976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 07/21/2023] [Indexed: 09/02/2023] Open
Abstract
Voltage-gated Ca2+ channels (VGCC) directly control muscle contraction and neurotransmitter release, and slower processes such as cell differentiation, migration, and death. They are potently inhibited by RGK GTP-ases (Rem, Rem2, Rad, and Gem/Kir), which decrease Ca2+ channel membrane expression, as well as directly inhibit membrane-resident channels. The mechanisms of membrane-resident channel inhibition are difficult to study because RGK-overexpression causes complete or near complete channel inhibition. Using titrated levels of Gem expression in Xenopus oocytes to inhibit WT P/Q-type calcium channels by ∼50%, we show that inhibition is dependent on channel inactivation. Interestingly, fast-inactivating channels, including Familial Hemiplegic Migraine mutants, are more potently inhibited than WT channels, while slow-inactivating channels, such as those expressed with the Cavβ2a auxiliary subunit, are spared. We found similar results in L-type channels, and, remarkably, Timothy Syndrome mutant channels were insensitive to Gem inhibition. Further results suggest that RGKs slow channel recovery from inactivation and further implicate RGKs as likely modulating factors in channelopathies.
Collapse
Affiliation(s)
- Salma Allam
- Department of Biology, Pace University, New York, NY, United States
| | - Rose Levenson-Palmer
- Department of Biological Sciences, Columbia University, New York, NY, United States
| | | | - Sukhjinder Kaur
- Department of Biology, Pace University, New York, NY, United States
| | - Bryan Cernuda
- Department of Biology, Pace University, New York, NY, United States
| | - Ananya Raman
- Department of Biology, Pace University, New York, NY, United States
| | - Audrey Booth
- Department of Biology, Pace University, New York, NY, United States
| | - Scott Dobbins
- Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Gabrielle Suppa
- Department of Biology, Pace University, New York, NY, United States
| | - Jian Yang
- Department of Biological Sciences, Columbia University, New York, NY, United States
| | - Zafir Buraei
- Department of Biology, Pace University, New York, NY, United States
| |
Collapse
|
4
|
John SR, Krauskopf B, Osinga HM, Rubin JE. Slow negative feedback enhances robustness of square-wave bursting. J Comput Neurosci 2023; 51:239-261. [PMID: 37067661 PMCID: PMC10181982 DOI: 10.1007/s10827-023-00846-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Revised: 01/17/2023] [Accepted: 02/15/2023] [Indexed: 04/18/2023]
Abstract
Square-wave bursting is an activity pattern common to a variety of neuronal and endocrine cell models that has been linked to central pattern generation for respiration and other physiological functions. Many of the reduced mathematical models that exhibit square-wave bursting yield transitions to an alternative pseudo-plateau bursting pattern with small parameter changes. This susceptibility to activity change could represent a problematic feature in settings where the release events triggered by spike production are necessary for function. In this work, we analyze how model bursting and other activity patterns vary with changes in a timescale associated with the conductance of a fast inward current. Specifically, using numerical simulations and dynamical systems methods, such as fast-slow decomposition and bifurcation and phase-plane analysis, we demonstrate and explain how the presence of a slow negative feedback associated with a gradual reduction of a fast inward current in these models helps to maintain the presence of spikes within the active phases of bursts. Therefore, although such a negative feedback is not necessary for burst production, we find that its presence generates a robustness that may be important for function.
Collapse
Affiliation(s)
- Sushmita Rose John
- Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, 15260, PA, USA
| | - Bernd Krauskopf
- Department of Mathematics, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand
| | - Hinke M Osinga
- Department of Mathematics, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand.
| | - Jonathan E Rubin
- Department of Mathematics, University of Pittsburgh, 301 Thackeray Hall, Pittsburgh, 15260, PA, USA.
| |
Collapse
|
5
|
Yeow SQZ, Loh KWZ, Soong TW. Calcium Channel Splice Variants and Their Effects in Brain and Cardiovascular Function. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:67-86. [DOI: 10.1007/978-981-16-4254-8_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
6
|
Vais H, Payne R, Paudel U, Li C, Foskett JK. Coupled transmembrane mechanisms control MCU-mediated mitochondrial Ca 2+ uptake. Proc Natl Acad Sci U S A 2020; 117:21731-21739. [PMID: 32801213 PMCID: PMC7474680 DOI: 10.1073/pnas.2005976117] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Ca2+ uptake by mitochondria regulates bioenergetics, apoptosis, and Ca2+ signaling. The primary pathway for mitochondrial Ca2+ uptake is the mitochondrial calcium uniporter (MCU), a Ca2+-selective ion channel in the inner mitochondrial membrane. MCU-mediated Ca2+ uptake is driven by the sizable inner-membrane potential generated by the electron-transport chain. Despite the large thermodynamic driving force, mitochondrial Ca2+ uptake is tightly regulated to maintain low matrix [Ca2+] and prevent opening of the permeability transition pore and cell death, while meeting dynamic cellular energy demands. How this is accomplished is controversial. Here we define a regulatory mechanism of MCU-channel activity in which cytoplasmic Ca2+ regulation of intermembrane space-localized MICU1/2 is controlled by Ca2+-regulatory mechanisms localized across the membrane in the mitochondrial matrix. Ca2+ that permeates through the channel pore regulates Ca2+ affinities of coupled inhibitory and activating sensors in the matrix. Ca2+ binding to the inhibitory sensor within the MCU amino terminus closes the channel despite Ca2+ binding to MICU1/2. Conversely, disruption of the interaction of MICU1/2 with the MCU complex disables matrix Ca2+ regulation of channel activity. Our results demonstrate how Ca2+ influx into mitochondria is tuned by coupled Ca2+-regulatory mechanisms on both sides of the inner mitochondrial membrane.
Collapse
Affiliation(s)
- Horia Vais
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Riley Payne
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Usha Paudel
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - Carmen Li
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| | - J Kevin Foskett
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104;
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104
| |
Collapse
|
7
|
Lei J, Liu X, Song M, Zhou Y, Fan J, Shen X, Xu X, Kapoor I, Zhu G, Wang (王觉进) J. Aberrant Exon 8/8a Splicing by Downregulated PTBP (Polypyrimidine Tract-Binding Protein) 1 Increases Ca V1.2 Dihydropyridine Resistance to Attenuate Vasodilation. Arterioscler Thromb Vasc Biol 2020; 40:2440-2453. [PMID: 32787518 DOI: 10.1161/atvbaha.120.315010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
OBJECTIVE Calcium channel blockers, such as dihydropyridines, are commonly used to inhibit enhanced activity of vascular CaV1.2 channels in hypertension. However, patients who are insensitive to such treatments develop calcium channel blocker-resistant hypertension. The function of CaV1.2 channel is diversified by alternative splicing, and the splicing factor PTBP (polypyrimidine tract-binding protein) 1 influences the utilization of mutually exclusive exon 8/8a of the CaV1.2 channel during neuronal development. Nevertheless, whether and how PTBP1 makes a role in the calcium channel blocker sensitivity of vascular CaV1.2 channels, and calcium channel blocker-induced vasodilation remains unknown. Approach and Results: We detected high expression of PTBP1 and, inversely, low expression of exon 8a in CaV1.2 channels (CaV1.2E8a) in rat arteries. In contrast, the opposite expression patterns were observed in brain and heart tissues. In comparison to normotensive rats, the expressions of PTBP1 and CaV1.2E8a channels were dysregulated in mesenteric arteries of hypertensive rats. Notably, PTBP1 expression was significantly downregulated, and CaV1.2E8a channels were aberrantly increased in dihydropyridine-resistant arteries compared with dihydropyridine-sensitive arteries of rats and human. In rat vascular smooth muscle cells, PTBP1 knockdown resulted in shifting of CaV1.2 exon 8 to 8a. Using patch-clamp recordings, we demonstrated a concomitant reduction of sensitivity of CaV1.2 channels to nifedipine, due to the higher expression of CaV1.2E8a isoform. In vascular myography experiments, small interfering RNA-mediated knockdown of PTBP1 attenuated nifedipine-induced vasodilation of rat mesenteric arteries. CONCLUSIONS PTBP1 finely modulates the sensitivities of CaV1.2 channels to dihydropyridine by shifting the utilization of exon 8/8a and resulting in changes of responses in dihydropyridine-induced vasodilation.
Collapse
Affiliation(s)
- Jianzhen Lei
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| | - Xiaoxin Liu
- Shanghai Chest Hospital, Shanghai Jiaotong University, China (X.L.)
| | - Miaomiao Song
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| | - Yingying Zhou
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| | - Jia Fan
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| | - Xiaowei Shen
- Department of Cardiovascular Surgery, the First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (X.S., X.X.)
| | - Xiaohan Xu
- Department of Cardiovascular Surgery, the First Affiliated Hospital of Nanjing Medical University, Jiangsu, China (X.S., X.X.)
| | - Isha Kapoor
- Department of Cancer Biology, Lerner Research Institute, Cleveland Clinic, OH (I.K.)
| | - Guoqing Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| | - Juejin Wang (王觉进)
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Jiangsu, China (J.L., M.S., Y.Z., J.F., G.Z., J.W.)
| |
Collapse
|
8
|
Bohannon BM, de la Cruz A, Wu X, Jowais JJ, Perez ME, Dykxhoorn DM, Liin SI, Larsson HP. Polyunsaturated fatty acid analogues differentially affect cardiac Na V, Ca V, and K V channels through unique mechanisms. eLife 2020; 9:51453. [PMID: 32207683 PMCID: PMC7159882 DOI: 10.7554/elife.51453] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 03/24/2020] [Indexed: 12/15/2022] Open
Abstract
The cardiac ventricular action potential depends on several voltage-gated ion channels, including NaV, CaV, and KV channels. Mutations in these channels can cause Long QT Syndrome (LQTS) which increases the risk for ventricular fibrillation and sudden cardiac death. Polyunsaturated fatty acids (PUFAs) have emerged as potential therapeutics for LQTS because they are modulators of voltage-gated ion channels. Here we demonstrate that PUFA analogues vary in their selectivity for human voltage-gated ion channels involved in the ventricular action potential. The effects of specific PUFA analogues range from selective for a specific ion channel to broadly modulating cardiac ion channels from all three families (NaV, CaV, and KV). In addition, a PUFA analogue selective for the cardiac IKs channel (Kv7.1/KCNE1) is effective in shortening the cardiac action potential in human-induced pluripotent stem cell-derived cardiomyocytes. Our data suggest that PUFA analogues could potentially be developed as therapeutics for LQTS and cardiac arrhythmia.
Collapse
Affiliation(s)
- Briana M Bohannon
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Alicia de la Cruz
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Xiaoan Wu
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Jessica J Jowais
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Marta E Perez
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| | - Derek M Dykxhoorn
- John P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, United States
| | - Sara I Liin
- Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - H Peter Larsson
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, United States
| |
Collapse
|
9
|
Alves JQ, Pernomian L, Silva CD, Gomes MS, de Oliveira AM, da Silva RS. Vascular tone and angiogenesis modulation by catecholamine coordinated to ruthenium. RSC Med Chem 2020; 11:497-510. [PMID: 33479651 DOI: 10.1039/c9md00573k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Accepted: 02/12/2020] [Indexed: 01/11/2023] Open
Abstract
Catecholamines participate in angiogenesis, an important tumor development process. However, the way catecholamines interact with their receptors has not been completely elucidated, and doubts still remain as to whether these interactions occur between catechol and/or amine sites and particular amino acid residues on the catecholamine receptors. To evaluate how catechol and amine groups contribute to angiogenesis, we immobilized the catechol site through ruthenium ion (Ru) coordination, to obtain species with the general formula [Ru(NH3)4(catecholamine-R)]Cl. We then assessed the angiogenic activity of the complexes in a chorioallantoic membrane model (CAM) and examined vascular reactivity and calcium mobilization in rat aortas and vascular cells. [Ru(NH3)4(catecholamine-R)]Cl acted as partial agonists and/or antagonists of their respective receptors and induced calcium mobilization. [Ru(NH3)4(isoproterenol)]+ [Ru(NH3)4(noradrenaline)]+, and [Ru(NH3)4(adrenaline)]+ behaved as antiangiogenic complexes, whereas [Ru(NH3)4(dopamine)]+ proved to be a proangiogenic complex. In conclusion, catecholamines and [Ru(NH3)4(catecholamine-R)]Cl can modulate angiogenesis, and catechol group availability can modify the way these complexes impact the vascular tone, suggesting that catecholamines and their receptors interact differently after catecholamine coordination to ruthenium.
Collapse
Affiliation(s)
- Jacqueline Querino Alves
- Faculty of Philosophy , Sciences and Letters of Ribeirão Preto - University of São Paulo (USP) , Department of Chemistry , Avenida Bandeirantes, 3900 , postal code 14.040-901 , Ribeirão Preto , São Paulo , Brazil
| | - Laena Pernomian
- Faculty of Pharmaceutical Sciences of Ribeirão Preto (FCFRP) - University of São Paulo (USP) , Department of Physics and Chemistry , Avenida do Café, s/n , postal code 14.040-903 , Ribeirão Preto , São Paulo , Brazil .
| | - Cássia Dias Silva
- Faculty of Philosophy , Sciences and Letters of Ribeirão Preto - University of São Paulo (USP) , Department of Chemistry , Avenida Bandeirantes, 3900 , postal code 14.040-901 , Ribeirão Preto , São Paulo , Brazil
| | - Mayara Santos Gomes
- Faculty of Pharmaceutical Sciences of Ribeirão Preto (FCFRP) - University of São Paulo (USP) , Department of Physics and Chemistry , Avenida do Café, s/n , postal code 14.040-903 , Ribeirão Preto , São Paulo , Brazil .
| | - Ana Maria de Oliveira
- Faculty of Pharmaceutical Sciences of Ribeirão Preto (FCFRP) - University of São Paulo (USP) , Department of Physics and Chemistry , Avenida do Café, s/n , postal code 14.040-903 , Ribeirão Preto , São Paulo , Brazil .
| | - Roberto Santana da Silva
- Faculty of Philosophy , Sciences and Letters of Ribeirão Preto - University of São Paulo (USP) , Department of Chemistry , Avenida Bandeirantes, 3900 , postal code 14.040-901 , Ribeirão Preto , São Paulo , Brazil.,Faculty of Pharmaceutical Sciences of Ribeirão Preto (FCFRP) - University of São Paulo (USP) , Department of Physics and Chemistry , Avenida do Café, s/n , postal code 14.040-903 , Ribeirão Preto , São Paulo , Brazil .
| |
Collapse
|
10
|
Bartels P, Yu D, Huang H, Hu Z, Herzig S, Soong TW. Alternative Splicing at N Terminus and Domain I Modulates Ca V1.2 Inactivation and Surface Expression. Biophys J 2019; 114:2095-2106. [PMID: 29742403 DOI: 10.1016/j.bpj.2018.03.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2017] [Revised: 03/12/2018] [Accepted: 03/27/2018] [Indexed: 10/17/2022] Open
Abstract
The CaV1.2 L-type calcium channel is a key conduit for Ca2+ influx to initiate excitation-contraction coupling for contraction of the heart and vasoconstriction of the arteries and for altering membrane excitability in neurons. Its α1C pore-forming subunit is known to undergo extensive alternative splicing to produce many CaV1.2 isoforms that differ in their electrophysiological and pharmacological properties. Here, we examined the structure-function relationship of human CaV1.2 with respect to the inclusion or exclusion of mutually exclusive exons of the N-terminus exons 1/1a and IS6 segment exons 8/8a. These exons showed tissue selectivity in their expression patterns: heart variant 1a/8a, one smooth-muscle variant 1/8, and a brain isoform 1/8a. Overall, the 1/8a, when coexpressed with CaVβ2a, displayed a significant and distinct shift in voltage-dependent activation and inactivation and inactivation kinetics as compared to the other three splice variants. Further analysis showed a clear additive effect of the hyperpolarization shift in V1/2inact of CaV1.2 channels containing exon 1 in combination with 8a. However, this additive effect was less distinct for V1/2act. However, the measured effects were β-subunit-dependent when comparing CaVβ2a with CaVβ3 coexpression. Notably, calcium-dependent inactivation mediated by local Ca2+-sensing via the N-lobe of calmodulin was significantly enhanced in exon-1-containing CaV1.2 as compared to exon-1a-containing CaV1.2 channels. At the cellular level, the current densities of the 1/8a or 1/8 variants were significantly larger than the 1a/8a and 1a/8 variants when coexpressed either with CaVβ2a or CaVβ3 subunit. This finding correlated well with a higher channel surface expression for the exon 1-CaV1.2 isoform that we quantified by protein surface-expression levels or by gating currents. Our data also provided a deeper molecular understanding of the altered biophysical properties of alternatively spliced human CaV1.2 channels by directly comparing unitary single-channel events with macroscopic whole-cell currents.
Collapse
Affiliation(s)
- Peter Bartels
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Dejie Yu
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Hua Huang
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Zhenyu Hu
- Department of Physiology, National University of Singapore, Singapore, Singapore
| | - Stefan Herzig
- Department of Pharmacology, University of Cologne, Cologne, Germany
| | - Tuck Wah Soong
- Department of Physiology, National University of Singapore, Singapore, Singapore; NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore; Neurobiology/Ageing Programme, National University of Singapore, Singapore, Singapore; National Neuroscience Institute, Singapore, Singapore.
| |
Collapse
|
11
|
Bazmi M, Escobar AL. How Ca 2+ influx is attenuated in the heart during a "fight or flight" response. J Gen Physiol 2019; 151:722-726. [PMID: 31004065 PMCID: PMC6572000 DOI: 10.1085/jgp.201912338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Bazmi and Escobar highlight a recent investigation of the mechanisms that regulate Ca2+ influx during sympathetic stimulation.
Collapse
Affiliation(s)
- Maedeh Bazmi
- Quantitative Systems Biology Program, School of Natural Sciences, University of California, Merced, Merced, CA
| | - Ariel L Escobar
- Department of Bioengineering, School of Engineering, University of California, Merced, Merced, CA
| |
Collapse
|
12
|
Giudicessi JR, Ackerman MJ. Calcium Revisited: New Insights Into the Molecular Basis of Long-QT Syndrome. Circ Arrhythm Electrophysiol 2018; 9:CIRCEP.116.002480. [PMID: 27390209 DOI: 10.1161/circep.116.002480] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Accepted: 05/27/2016] [Indexed: 12/12/2022]
Affiliation(s)
- John R Giudicessi
- From the Internal Medicine Residency and Clinician-Investigator Programs, Department of Medicine (J.R.G.) and Departments of Cardiovascular Diseases, Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (M.J.A.), Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- From the Internal Medicine Residency and Clinician-Investigator Programs, Department of Medicine (J.R.G.) and Departments of Cardiovascular Diseases, Pediatrics (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (M.J.A.), Windland Smith Rice Sudden Death Genomics Laboratory, Mayo Clinic, Rochester, MN.
| |
Collapse
|
13
|
Effect of the spider toxin Tx3-3 on spinal processing of sensory information in naive and neuropathic rats: an in vivo electrophysiological study. Pain Rep 2017; 2:e610. [PMID: 29392225 PMCID: PMC5741365 DOI: 10.1097/pr9.0000000000000610] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 05/20/2017] [Accepted: 05/24/2017] [Indexed: 11/25/2022] Open
Abstract
The P/Q- and R-type voltage-gated calcium channel blocker Tx3-3 inhibits dorsal horn neuronal response of rats with greater potency after nerve injury. Introduction: Drugs that counteract nociceptive transmission in the spinal dorsal horn preferentially after nerve injury are being pursued as possible neuropathic pain treatments. In a previous behavioural study, the peptide toxin Tx3-3, which blocks P/Q- and R-type voltage-gated calcium channels, was effective in neuropathic pain models. Objectives: In the present study, we aimed to investigate the effect of Tx3-3 on dorsal horn neuronal responses in rats under physiological conditions and neuropathic pain condition induced by spinal nerve ligation (SNL). Methods: In vivo electrophysiological recordings of dorsal horn neuronal response to electrical and natural (mechanical and thermal) stimuli were made in rats under normal physiological state (naive rats) or after the SNL model of neuropathic pain. Results: Tx3-3 (0.3–100 pmol/site) exhibited greater inhibitory effect on electrical-evoked neuronal response of SNL rats than naive rats, inhibiting nociceptive C-fibre and Aδ-fibre responses only in SNL rats. The wind-up of neurones, a measurement of spinal cord hyperexcitability, was also more susceptible to a dose-related inhibition by Tx3-3 after nerve injury. Moreover, Tx3-3 exhibited higher potency to inhibit mechanical- and thermal-evoked neuronal response in conditions of neuropathy. Conclusion: Tx3-3 mediated differential inhibitory effect under physiological and neuropathic conditions, exhibiting greater potency in conditions of neuropathic pain.
Collapse
|
14
|
Berecki G, Motin L, Adams DJ. Mechanism of direct Cav2.2 channel block by the κ-opioid receptor agonist U50488H. Neuropharmacology 2016; 109:49-58. [DOI: 10.1016/j.neuropharm.2016.05.019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 05/13/2016] [Accepted: 05/27/2016] [Indexed: 11/29/2022]
|
15
|
Aviner B, Gradwohl G, Bliznyuk A, Grossman Y. Selective pressure modulation of synaptic voltage-dependent calcium channels-involvement in HPNS mechanism. J Cell Mol Med 2016; 20:1872-88. [PMID: 27273194 PMCID: PMC5020619 DOI: 10.1111/jcmm.12877] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 03/21/2016] [Indexed: 11/28/2022] Open
Abstract
Exposure to hyperbaric pressure (HP) exceeding 100 msw (1.1 MPa) is known to cause a constellation of motor and cognitive impairments named high-pressure neurological syndrome (HPNS), considered to be the result of synaptic transmission alteration. Long periods of repetitive HP exposure could be an occupational risk for professional deep-sea divers. Previous studies have indicated the modulation of presynaptic Ca(2+) currents based on synaptic activity modified by HP. We have recently demonstrated that currents in genetically identified cellular voltage-dependent Ca(2+) channels (VDCCs), CaV 1.2 and CaV 3.2 are selectively affected by HP. This work further elucidates the HPNS mechanism by examining HP effect on Ca(2+) currents in neuronal VDCCs, CaV 2.2 and CaV 2.1, which are prevalent in presynaptic terminals, expressed in Xenopus oocytes. HP augmented the CaV 2.2 current amplitude, much less so in a channel variation containing an additional modulatory subunit, and had almost no effect on the CaV 2.1 currents. HP differentially affected the channels' kinetics. It is, therefore, suggested that HPNS signs and symptoms arise, at least in part, from pressure modulation of various VDCCs.
Collapse
Affiliation(s)
- Ben Aviner
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
| | - Gideon Gradwohl
- Department of Physics, Jerusalem College of Technology, Jerusalem, Israel
| | - Alice Bliznyuk
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| | - Yoram Grossman
- Department of Physiology and Neurobiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel
| |
Collapse
|
16
|
Himeno Y, Asakura K, Cha CY, Memida H, Powell T, Amano A, Noma A. A human ventricular myocyte model with a refined representation of excitation-contraction coupling. Biophys J 2016. [PMID: 26200878 DOI: 10.1016/j.bpj.2015.06.017] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cardiac Ca(2+)-induced Ca(2+) release (CICR) occurs by a regenerative activation of ryanodine receptors (RyRs) within each Ca(2+)-releasing unit, triggered by the activation of L-type Ca(2+) channels (LCCs). CICR is then terminated, most probably by depletion of Ca(2+) in the junctional sarcoplasmic reticulum (SR). Hinch et al. previously developed a tightly coupled LCC-RyR mathematical model, known as the Hinch model, that enables simulations to deal with a variety of functional states of whole-cell populations of a Ca(2+)-releasing unit using a personal computer. In this study, we developed a membrane excitation-contraction model of the human ventricular myocyte, which we call the human ventricular cell (HuVEC) model. This model is a hybrid of the most recent HuVEC models and the Hinch model. We modified the Hinch model to reproduce the regenerative activation and termination of CICR. In particular, we removed the inactivated RyR state and separated the single step of RyR activation by LCCs into triggering and regenerative steps. More importantly, we included the experimental measurement of a transient rise in Ca(2+) concentrations ([Ca(2+)], 10-15 μM) during CICR in the vicinity of Ca(2+)-releasing sites, and thereby calculated the effects of the local Ca(2+) gradient on CICR as well as membrane excitation. This HuVEC model successfully reconstructed both membrane excitation and key properties of CICR. The time course of CICR evoked by an action potential was accounted for by autonomous changes in an instantaneous equilibrium open probability of couplons. This autonomous time course was driven by a core feedback loop including the pivotal local [Ca(2+)], influenced by a time-dependent decay in the SR Ca(2+) content during CICR.
Collapse
Affiliation(s)
- Yukiko Himeno
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Keiichi Asakura
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan; Nippon Shinyaku Co., Ltd., Kyoto, Japan
| | - Chae Young Cha
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan; Oxford Centre for Diabetes Endocrinology and Metabolism, University of Oxford, Oxford, UK
| | - Hiraku Memida
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Trevor Powell
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Akira Amano
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan
| | - Akinori Noma
- Biosimulation Research Center, College of Life Sciences, Ritsumeikan University, Shiga, Japan.
| |
Collapse
|
17
|
Zhu L, McDavid S, Currie KPM. "Slow" Voltage-Dependent Inactivation of CaV2.2 Calcium Channels Is Modulated by the PKC Activator Phorbol 12-Myristate 13-Acetate (PMA). PLoS One 2015. [PMID: 26222492 PMCID: PMC4519294 DOI: 10.1371/journal.pone.0134117] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
CaV2.2 (N-type) voltage-gated calcium channels (Ca2+ channels) play key roles in neurons and neuroendocrine cells including the control of cellular excitability, neurotransmitter / hormone secretion, and gene expression. Calcium entry is precisely controlled by channel gating properties including multiple forms of inactivation. “Fast” voltage-dependent inactivation is relatively well-characterized and occurs over the tens-to- hundreds of milliseconds timeframe. Superimposed on this is the molecularly distinct, but poorly understood process of “slow” voltage-dependent inactivation, which develops / recovers over seconds-to-minutes. Protein kinases can modulate “slow” inactivation of sodium channels, but little is known about if/how second messengers control “slow” inactivation of Ca2+ channels. We investigated this using recombinant CaV2.2 channels expressed in HEK293 cells and native CaV2 channels endogenously expressed in adrenal chromaffin cells. The PKC activator phorbol 12-myristate 13-acetate (PMA) dramatically prolonged recovery from “slow” inactivation, but an inactive control (4α-PMA) had no effect. This effect of PMA was prevented by calphostin C, which targets the C1-domain on PKC, but only partially reduced by inhibitors that target the catalytic domain of PKC. The subtype of the channel β-subunit altered the kinetics of inactivation but not the magnitude of slowing produced by PMA. Intracellular GDP-β-S reduced the effect of PMA suggesting a role for G proteins in modulating “slow” inactivation. We postulate that the kinetics of recovery from “slow” inactivation could provide a molecular memory of recent cellular activity and help control CaV2 channel availability, electrical excitability, and neurotransmission in the seconds-to-minutes timeframe.
Collapse
Affiliation(s)
- Lei Zhu
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Sarah McDavid
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
| | - Kevin P. M. Currie
- Department of Anesthesiology, Vanderbilt University, Nashville, Tennessee, United States of America
- Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, United States of America
- Vanderbilt Brain Institute, Vanderbilt University, Nashville, Tennessee, United States of America
- * E-mail:
| |
Collapse
|
18
|
Aviner B, Gradwohl G, Mor Aviner M, Levy S, Grossman Y. Selective modulation of cellular voltage-dependent calcium channels by hyperbaric pressure-a suggested HPNS partial mechanism. Front Cell Neurosci 2014; 8:136. [PMID: 24904281 PMCID: PMC4034351 DOI: 10.3389/fncel.2014.00136] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Accepted: 04/30/2014] [Indexed: 11/30/2022] Open
Abstract
Professional deep sea divers experience motor and cognitive impairment, known as High Pressure Neurological Syndrome (HPNS), when exposed to pressures of 100 msw (1.1 MPa) and above, considered to be the result of synaptic transmission alteration. Previous studies have indicated modulation of presynaptic Ca2+ currents at high pressure. We directly measured for the first time pressure effects on the currents of voltage dependent Ca2+ channels (VDCCs) expressed in Xenopus oocytes. Pressure selectivity augmented the current in CaV1.2 and depressed it in CaV3.2 channels. Pressure application also affected the channels' kinetics, such as ƮRise, ƮDecay. Pressure modulation of VDCCs seems to play an important role in generation of HPNS signs and symptoms.
Collapse
Affiliation(s)
- Ben Aviner
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Gideon Gradwohl
- Department of Physics, Jerusalem College of Technology Jerusalem, Israel
| | - Merav Mor Aviner
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Shiri Levy
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| | - Yoram Grossman
- Department of Physiology and Neurobiology, Ben Gurion University of the Negev Beer Sheva, Israel
| |
Collapse
|
19
|
Liao P, Soong TW. Understanding alternative splicing of Cav1.2 calcium channels for a new approach towards individualized medicine. J Biomed Res 2013; 24:181-6. [PMID: 23554629 PMCID: PMC3596553 DOI: 10.1016/s1674-8301(10)60027-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Indexed: 11/28/2022] Open
Abstract
Calcium channel blockers (CCBs) are widely used to treat cardiovascular diseases such as hypertension, angina pectoris, hypertrophic cardiomyopathy, and supraventricular tachycardia. CCBs selectively inhibit the inward flow of calcium ions through voltage-gated calcium channels, particularly Cav1.2, that are expressed in the cardiovascular system. Changes to the molecular structure of Cav1.2 channels could affect sensitivity of the channels to blockade by CCBs. Recently, extensive alternative splicing was found in Cav1.2 channels that generated wide phenotypic variations. Cardiac and smooth muscles express slightly different, but functionally important Cav1.2 splice variants. Alternative splicing could also modulate the gating properties of the channels and giving rise to different responses to inhibition by CCBs. Importantly, alternative splicing of Cav1.2 channels may play an important role to influence the outcome of many cardiovascular disorders. Therefore, the understanding of how alternative splicing impacts Cav1.2 channels pharmacology in various diseases and different organs may provide the possibility for individualized therapy with minimal side effects.
Collapse
Affiliation(s)
- Ping Liao
- National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433
| | | |
Collapse
|
20
|
Adams DJ, Berecki G. Mechanisms of conotoxin inhibition of N-type (Ca(v)2.2) calcium channels. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:1619-28. [PMID: 23380425 DOI: 10.1016/j.bbamem.2013.01.019] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 01/16/2013] [Accepted: 01/19/2013] [Indexed: 12/27/2022]
Abstract
N-type (Ca(v)2.2) voltage-gated calcium channels (VGCC) transduce electrical activity into other cellular functions, regulate calcium homeostasis and play a major role in processing pain information. Although the distribution and function of these channels vary widely among different classes of neurons, they are predominantly expressed in nerve terminals, where they control neurotransmitter release. To date, genetic and pharmacological studies have identified that high-threshold, N-type VGCCs are important for pain sensation in disease models. This suggests that N-type VGCC inhibitors or modulators could be developed into useful drugs to treat neuropathic pain. This review discusses the role of N-type (Ca(v)2.2) VGCCs in nociception and pain transmission through primary sensory dorsal root ganglion (DRG) neurons (nociceptors). It also outlines the potent and selective inhibition of N-type VGCCs by conotoxins, small disulfide-rich peptides isolated from the venom of marine cone snails. Of these conotoxins, ω-conotoxins are selective N-type VGCC antagonists that preferentially block nociception in inflammatory pain models, and allodynia and/or hyperalgesia in neuropathic pain models. Another conotoxin family, α-conotoxins, were initially proposed as competitive antagonists of muscle and neuronal nicotinic acetylcholine receptors (nAChR). Surprisingly, however, α-conotoxins Vc1.1 and RgIA, also potently inhibit N-type VGCC currents in the sensory DRG neurons of rodents and α9 nAChR knockout mice, via intracellular signaling mediated by G protein-coupled GABAB receptors. Understanding how conotoxins inhibit VGCCs is critical for developing these peptides into analgesics and may result in better pain management. This article is part of a Special Issue entitled: Calcium channels.
Collapse
Affiliation(s)
- David J Adams
- Health Innovations Research Institute, RMIT University, Melbourne, Victoria, Australia.
| | | |
Collapse
|
21
|
Soldatov NM. Molecular Determinants of Cav1.2 Calcium Channel Inactivation. ISRN MOLECULAR BIOLOGY 2012; 2012:691341. [PMID: 27335667 PMCID: PMC4890872 DOI: 10.5402/2012/691341] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/13/2012] [Indexed: 12/13/2022]
Abstract
Voltage-gated L-type Cav1.2 calcium channels couple membrane depolarization to transient increase in cytoplasmic free Ca2+ concentration that initiates a number of essential cellular functions including cardiac and vascular muscle contraction, gene expression, neuronal plasticity, and exocytosis. Inactivation or spontaneous termination of the calcium current through Cav1.2 is a critical step in regulation of these processes. The pathophysiological significance of this process is manifested in hypertension, heart failure, arrhythmia, and a number of other diseases where acceleration of the calcium current decay should present a benefit function. The central issue of this paper is the inactivation of the Cav1.2 calcium channel mediated by multiple determinants.
Collapse
|
22
|
|
23
|
Antinociceptive effect of Brazilian armed spider venom toxin Tx3-3 in animal models of neuropathic pain. Pain 2011; 152:2224-2232. [PMID: 21570770 DOI: 10.1016/j.pain.2011.04.015] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 02/04/2011] [Accepted: 04/08/2011] [Indexed: 11/23/2022]
Abstract
Venoms peptides have produced exceptional sources for drug development to treat pain. In this study we examined the antinociceptive and side effects of Tx3-3, a peptide toxin isolated from Phoneutria nigriventer venom, which inhibits high-voltage-dependent calcium channels (VDCC), preferentially P/Q and R-type VDCC. We tested the effects of Tx3-3 in animal models of nociceptive (tail-flick test), neuropathic (partial sciatic nerve ligation and streptozotocin-induced diabetic neuropathy), and inflammatory (intraplantar complete Freund's adjuvant) pain. In the tail-flick test, both intrathecal (i.t.) and intracerebroventricular (i.c.v.) injection of Tx3-3 in mice caused a short-lasting effect (ED(50) and 95% confidence intervals of 8.8 [4.1-18.8] and 3.7 [1.6-8.4] pmol/site for i.t. and i.c.v. injection, respectively), without impairing motor functions, at least at doses 10-30 times higher than the effective dose. By comparison, ω-conotoxin MVIIC, a P/Q and N-type VDCC blocker derived from Conus magus venom, caused significant motor impairment at doses close to efficacious dose in tail flick test. Tx3-3 showed a long-lasting antinociceptive effect in neuropathic pain models. Intrathecal injection of Tx3-3 (30 pmol/site) decreased both mechanical allodynia produced by sciatic nerve injury in mice and streptozotocin-induced allodynia in mice and rats. On the other hand, i.t. injection of Tx3-3 did not alter inflammatory pain. Taken together, our data show that Tx3-3 shows prevalent antinociceptive effects in the neuropathic pain models and does not cause adverse motor effects at antinociceptive efficacious doses, suggesting that this peptide toxin holds promise as a novel therapeutic agent for the control of neuropathic pain. The Brazilian armed spider Tx3-3, a new P/Q and R-type calcium channel blocker, effectively alleviates allodynia in animal neuropathic pain models.
Collapse
|
24
|
Bett GCL, Dinga-Madou I, Zhou Q, Bondarenko VE, Rasmusson RL. A model of the interaction between N-type and C-type inactivation in Kv1.4 channels. Biophys J 2011; 100:11-21. [PMID: 21190652 DOI: 10.1016/j.bpj.2010.11.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Revised: 09/24/2010] [Accepted: 11/08/2010] [Indexed: 01/12/2023] Open
Abstract
Kv1.4 channels are Shaker-related voltage-gated potassium channels with two distinct inactivation mechanisms. Fast N-type inactivation operates by a ball-and-chain mechanism. Slower C-type inactivation is not so well defined, but involves intracellular and extracellular conformational changes of the channel. We studied the interaction between inactivation mechanisms using two-electrode voltage-clamp of Kv1.4 and Kv1.4ΔN (amino acids 2-146 deleted to remove N-type inactivation) heterologously expressed in Xenopus oocytes. We manipulated C-type inactivation by introducing a lysine-tyrosine point mutation (K532Y, equivalent to Shaker T449Y) that diminishes C-type inactivation. We used experimental data to develop a comprehensive computer model of Kv1.4 channels to determine the interaction between activation and N- and C-type inactivation mechanisms needed to replicate the experimental data. C-type inactivation began at lower voltage preactivated states, whereas N-type inactivation was coupled directly to the open state. A model with distinct N- and C-type inactivated states was not able to reproduce experimental data, and direct transitions between N- and C-type inactivated states were required, i.e., there is coupling between N- and C-type inactivated states. C-type inactivation is the rate-limiting step determining recovery from inactivation, so understanding C-type inactivation, and how it is coupled to N-type inactivation, is critical in understanding how channels act to repetitive stimulation.
Collapse
Affiliation(s)
- Glenna C L Bett
- Department of Gynecology-Obstetrics, The State University of New York, University at Buffalo, Buffalo, New York, USA
| | | | | | | | | |
Collapse
|
25
|
Zhang HY, Liao P, Wang JJ, Yu DJ, Soong TW. Alternative splicing modulates diltiazem sensitivity of cardiac and vascular smooth muscle Ca(v)1.2 calcium channels. Br J Pharmacol 2010; 160:1631-40. [PMID: 20649567 DOI: 10.1111/j.1476-5381.2010.00798.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND AND PURPOSE As a calcium channel blocker, diltiazem acts mainly on the voltage-gated calcium channels, Ca(v)1.2, for its beneficial effects in cardiovascular diseases such as hypertension, angina and/or supraventricular arrhythmias. However, the effects of diltiazem on different isoforms of Ca(v)1.2 channels expressed in heart and vascular smooth muscles remain to be investigated. Here, we characterized the effects of diltiazem on the splice variants of Ca(v)1.2 channels, predominant in cardiac and vascular smooth muscles. EXPERIMENTAL APPROACH Cardiac and smooth muscle isoforms of Ca(v)1.2 channels were expressed in human embryonic kidney cells and their electrophysiological properties were characterized using whole-cell patch-clamp techniques. KEY RESULTS Under closed-channel and use-dependent block (0.03 Hz), cardiac splice variant Ca(v)1.2CM was less sensitive to diltiazem than two major smooth muscle splice variants, Ca(v)1.2SM and Ca(v)1.2b. Ca(v)1.2CM has a more positive half-inactivation potential than the smooth muscle channels, and diltiazem shifted it less to negative potential. Additionally, the current decay was slower in Ca(v)1.2CM channels. When we modified alternatively spliced exons of cardiac Ca(v)1.2CM channels into smooth muscle exons, we found that all three loci contribute to the different diltiazem sensitivity between cardiac and smooth muscle splice isoforms. CONCLUSIONS AND IMPLICATIONS Alternative splicing of Ca(v)1.2 channels modifies diltiazem sensitivity in the heart and blood vessels. Gating properties altered by diltiazem are different in the three channels.
Collapse
Affiliation(s)
- Heng Yu Zhang
- Department of Cardiology, West China School of Medicine, Sichuan University, Chengdu, China
| | | | | | | | | |
Collapse
|
26
|
Zhou Q, Bett GCL. Regulation of the voltage-insensitive step of HERG activation by extracellular pH. Am J Physiol Heart Circ Physiol 2010; 298:H1710-8. [PMID: 20363888 DOI: 10.1152/ajpheart.01246.2009] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Human ether-à-go-go-related gene (HERG, Kv11.1, KCNH2) voltage-gated K(+) channels dominate cardiac action potential repolarization. In addition, HERG channels play a role in neuronal and smooth cell excitability as well as cancer pathology. Extracellular pH (pH(o)) is modified during myocardial ischemia, inflammation, and respiratory alkalosis, so understanding the response of HERG channels to changes in pH is of clinical significance. The relationship between pH(o) and HERG channel gating appears complex. Acidification has previously been reported to speed, slow, or have no effect on activation. We therefore undertook comprehensive analysis of the effect of pH(o) on HERG channel activation. HERG channels have unique and complex activation gating characteristics with both voltage-sensitive and voltage-insensitive steps in the activation pathway. Acidosis decreased the activation rate, suppressed peak current, and altered the sigmoidicity of gating near threshold potentials. At positive voltages, where the voltage-insensitive transition is rate limiting, pH(o) modified the voltage-insensitive step with a pK(a) similar to that of histidine. Hill coefficient analysis was incompatible with a coefficient of 1 but was well described by a Hill coefficient of 4. We derived a pH(o)-sensitive term for a five-state Markov model of HERG channel gating. This model demonstrates the mechanism of pH(o) sensitivity in HERG channel activation. Our experimental data and mathematical model demonstrate that the pH(o) sensitivity of HERG channel activation is dominated by the pH(o) sensitivity of the voltage-insensitive step, in a fashion that is compatible with the presence of at least one proton-binding site on each subunit of the channel tetramer.
Collapse
Affiliation(s)
- Qinlian Zhou
- Department of Physiology and Biophysics, 124 Sherman Hall, State Univ. of New York, Univ. at Buffalo, Buffalo, NY 14214, USA
| | | |
Collapse
|
27
|
Tadross MR, Ben Johny M, Yue DT. Molecular endpoints of Ca2+/calmodulin- and voltage-dependent inactivation of Ca(v)1.3 channels. ACTA ACUST UNITED AC 2010; 135:197-215. [PMID: 20142517 PMCID: PMC2828906 DOI: 10.1085/jgp.200910308] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Ca2+/calmodulin- and voltage-dependent inactivation (CDI and VDI) comprise vital prototypes of Ca2+ channel modulation, rich with biological consequences. Although the events initiating CDI and VDI are known, their downstream mechanisms have eluded consensus. Competing proposals include hinged-lid occlusion of channels, selectivity filter collapse, and allosteric inhibition of the activation gate. Here, novel theory predicts that perturbations of channel activation should alter inactivation in distinctive ways, depending on which hypothesis holds true. Thus, we systematically mutate the activation gate, formed by all S6 segments within CaV1.3. These channels feature robust baseline CDI, and the resulting mutant library exhibits significant diversity of activation, CDI, and VDI. For CDI, a clear and previously unreported pattern emerges: activation-enhancing mutations proportionately weaken inactivation. This outcome substantiates an allosteric CDI mechanism. For VDI, the data implicate a “hinged lid–shield” mechanism, similar to a hinged-lid process, with a previously unrecognized feature. Namely, we detect a “shield” in CaV1.3 channels that is specialized to repel lid closure. These findings reveal long-sought downstream mechanisms of inactivation and may furnish a framework for the understanding of Ca2+ channelopathies involving S6 mutations.
Collapse
Affiliation(s)
- Michael R Tadross
- Department of Biomedical Engineering, The Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
| | | | | |
Collapse
|
28
|
Brunet S, Scheuer T, Catterall WA. Cooperative regulation of Ca(v)1.2 channels by intracellular Mg(2+), the proximal C-terminal EF-hand, and the distal C-terminal domain. ACTA ACUST UNITED AC 2009; 134:81-94. [PMID: 19596806 PMCID: PMC2717695 DOI: 10.1085/jgp.200910209] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
L-type Ca(2+) currents conducted by Ca(v)1.2 channels initiate excitation-contraction coupling in cardiac myocytes. Intracellular Mg(2+) (Mg(i)) inhibits the ionic current of Ca(v)1.2 channels. Because Mg(i) is altered in ischemia and heart failure, its regulation of Ca(v)1.2 channels is important in understanding cardiac pathophysiology. Here, we studied the effects of Mg(i) on voltage-dependent inactivation (VDI) of Ca(v)1.2 channels using Na(+) as permeant ion to eliminate the effects of permeant divalent cations that engage the Ca(2+)-dependent inactivation process. We confirmed that increased Mg(i) reduces peak ionic currents and increases VDI of Ca(v)1.2 channels in ventricular myocytes and in transfected cells when measured with Na(+) as permeant ion. The increased rate and extent of VDI caused by increased Mg(i) were substantially reduced by mutations of a cation-binding residue in the proximal C-terminal EF-hand, consistent with the conclusion that both reduction of peak currents and enhancement of VDI result from the binding of Mg(i) to the EF-hand (K(D) approximately 0.9 mM) near the resting level of Mg(i) in ventricular myocytes. VDI was more rapid for L-type Ca(2+) currents in ventricular myocytes than for Ca(v)1.2 channels in transfected cells. Coexpression of Ca(v)beta(2b) subunits and formation of an autoinhibitory complex of truncated Ca(v)1.2 channels with noncovalently bound distal C-terminal domain (DCT) both increased VDI in transfected cells, indicating that the subunit structure of the Ca(v)1.2 channel greatly influences its VDI. The effects of noncovalently bound DCT on peak current amplitude and VDI required Mg(i) binding to the proximal C-terminal EF-hand and were prevented by mutations of a key divalent cation-binding amino acid residue. Our results demonstrate cooperative regulation of peak current amplitude and VDI of Ca(v)1.2 channels by Mg(i), the proximal C-terminal EF-hand, and the DCT, and suggest that conformational changes that regulate VDI are propagated from the DCT through the proximal C-terminal EF-hand to the channel-gating mechanism.
Collapse
Affiliation(s)
- Sylvain Brunet
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA.
| | | | | |
Collapse
|
29
|
Walsh CP, Davies A, Butcher AJ, Dolphin AC, Kitmitto A. Three-dimensional structure of CaV3.1: comparison with the cardiac L-type voltage-gated calcium channel monomer architecture. J Biol Chem 2009; 284:22310-22321. [PMID: 19520861 PMCID: PMC2755954 DOI: 10.1074/jbc.m109.017152] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calcium entry through voltage-gated calcium channels has widespread cellular effects upon a host of physiological processes including neuronal excitability, muscle excitation-contraction coupling, and secretion. Using single particle analysis methods, we have determined the first three-dimensional structure, at 23 A resolution, for a member of the low voltage-activated voltage-gated calcium channel family, CaV3.1, a T-type channel. CaV3.1 has dimensions of approximately 115x85x95 A, composed of two distinct segments. The cytoplasmic densities form a vestibule below the transmembrane domain with the C terminus, unambiguously identified by the presence of a His tag being approximately 65 A long and curling around the base of the structure. The cytoplasmic assembly has a large exposed surface area that may serve as a signaling hub with the C terminus acting as a "fishing rod" to bind regulatory proteins. We have also determined a three-dimensional structure, at a resolution of 25 A, for the monomeric form of the cardiac L-type voltage-gated calcium (high voltage-activated) channel with accessory proteins beta and alpha2delta bound to the ion channel polypeptide CaV1.2. Comparison with the skeletal muscle isoform finds a good match particularly with respect to the conformation, size, and shape of the domain identified as that formed by alpha2. Furthermore, modeling of the CaV3.1 structure (analogous to CaV1.2 at these resolutions) into the heteromeric L-type voltage-gated calcium channel complex volume reveals multiple interaction sites for beta-CaV1.2 binding and for the first time identifies the size and organization of the alpha2delta polypeptides.
Collapse
Affiliation(s)
- Conor P Walsh
- Cardiovascular Medicine, School of Clinical and Laboratory Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9NT
| | - Anthony Davies
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Adrian J Butcher
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Ashraf Kitmitto
- Cardiovascular Medicine, School of Clinical and Laboratory Sciences, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9NT
| |
Collapse
|
30
|
Findeisen F, Minor DL. Disruption of the IS6-AID linker affects voltage-gated calcium channel inactivation and facilitation. ACTA ACUST UNITED AC 2009; 133:327-43. [PMID: 19237593 PMCID: PMC2654080 DOI: 10.1085/jgp.200810143] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Two processes dominate voltage-gated calcium channel (CaV) inactivation: voltage-dependent inactivation (VDI) and calcium-dependent inactivation (CDI). The CaVβ/CaVα1-I-II loop and Ca2+/calmodulin (CaM)/CaVα1–C-terminal tail complexes have been shown to modulate each, respectively. Nevertheless, how each complex couples to the pore and whether each affects inactivation independently have remained unresolved. Here, we demonstrate that the IS6–α-interaction domain (AID) linker provides a rigid connection between the pore and CaVβ/I-II loop complex by showing that IS6-AID linker polyglycine mutations accelerate CaV1.2 (L-type) and CaV2.1 (P/Q-type) VDI. Remarkably, mutations that either break the rigid IS6-AID linker connection or disrupt CaVβ/I-II association sharply decelerate CDI and reduce a second Ca2+/CaM/CaVα1–C-terminal–mediated process known as calcium-dependent facilitation. Collectively, the data strongly suggest that components traditionally associated solely with VDI, CaVβ and the IS6-AID linker, are essential for calcium-dependent modulation, and that both CaVβ-dependent and CaM-dependent components couple to the pore by a common mechanism requiring CaVβ and an intact IS6-AID linker.
Collapse
Affiliation(s)
- Felix Findeisen
- Cardiovascular Research Institute, Department of Biochemistry and Biophysics, California Institute for Quantitative Biosciences, University of California, San Francisco, CA 94158, USA
| | | |
Collapse
|
31
|
Zhang Y, Chen YH, Bangaru SD, He L, Abele K, Tanabe S, Kozasa T, Yang J. Origin of the voltage dependence of G-protein regulation of P/Q-type Ca2+ channels. J Neurosci 2008; 28:14176-88. [PMID: 19109500 PMCID: PMC2685181 DOI: 10.1523/jneurosci.1350-08.2008] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
G-protein (Gbetagamma)-mediated voltage-dependent inhibition of N- and P/Q-type Ca(2+) channels contributes to presynaptic inhibition and short-term synaptic plasticity. The voltage dependence derives from the dissociation of Gbetagamma from the inhibited channels, but the underlying molecular and biophysical mechanisms remain largely unclear. In this study we investigated the role in this process of Ca(2+) channel beta subunit (Ca(v)beta) and a rigid alpha-helical structure between the alpha-interacting domain (AID), the primary Ca(v)beta docking site on the channel alpha(1) subunit, and the pore-lining IS6 segment. Gbetagamma inhibition of P/Q-type channels was reconstituted in giant inside-out membrane patches from Xenopus oocytes. Large populations of channels devoid of Ca(v)beta were produced by washing out a mutant Ca(v)beta with a reduced affinity for the AID. These beta-less channels were still inhibited by Gbetagamma, but without any voltage dependence, indicating that Ca(v)beta is indispensable for voltage-dependent Gbetagamma inhibition. A truncated Ca(v)beta containing only the AID-binding guanylate kinase (GK) domain could fully confer voltage dependence to Gbetagamma inhibition. Gbetagamma did not alter inactivation properties, and channels recovered from Gbetagamma inhibition exhibited the same activation property as un-inhibited channels, indicating that Gbetagamma does not dislodge Ca(v)beta from the inhibited channel. Furthermore, voltage-dependent Gbetagamma inhibition was abolished when the rigid alpha-helix between the AID and IS6 was disrupted by insertion of multiple glycines, which also eliminated Ca(v)beta regulation of channel gating, revealing a pivotal role of this rigid alpha-helix in both processes. These results suggest that depolarization-triggered movement of IS6, coupled to the subsequent conformational change of the Gbetagamma-binding pocket through a rigid alpha-helix induced partly by the Ca(v)beta GK domain, causes the dissociation of Gbetagamma and is fundamental to voltage-dependent Gbetagamma inhibition.
Collapse
Affiliation(s)
- Yun Zhang
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| | - Yu-hang Chen
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| | - Saroja D. Bangaru
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| | - Linling He
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| | - Kathryn Abele
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| | - Shihori Tanabe
- 2Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612
| | - Tohru Kozasa
- 2Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612
| | - Jian Yang
- 1Department of Biological Sciences, Columbia University, New York, New York 10027, and
| |
Collapse
|
32
|
Hagalili Y, Bachnoff N, Atlas D. The Voltage-Gated Ca2+ Channel Is the Ca2+ Sensor Protein of Secretion. Biochemistry 2008; 47:13822-30. [DOI: 10.1021/bi801619f] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yamit Hagalili
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904 Israel
| | - Niv Bachnoff
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904 Israel
| | - Daphne Atlas
- Department of Biological Chemistry, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904 Israel
| |
Collapse
|
33
|
Altered functional properties of a TRPM2 variant in Guamanian ALS and PD. Proc Natl Acad Sci U S A 2008; 105:18029-34. [PMID: 19004782 DOI: 10.1073/pnas.0808218105] [Citation(s) in RCA: 90] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Two related neurodegenerative disorders, Western Pacific amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD), originally occurred at a high incidence on Guam, in the Kii peninsula of Japan, and in southern West New Guinea more than 50 years ago. These three foci shared a unique mineral environment characterized by the presence of severely low levels of Ca(2+) and Mg(2+), coupled with high levels of bioavailable transition metals in the soil and drinking water. Epidemiological studies suggest that genetic factors also contribute to the etiology of these disorders. Here, we report that a variant of the transient receptor potential melastatin 2 (TRPM2) gene may confer susceptibility to these diseases. TRPM2 encodes a calcium-permeable cation channel highly expressed in the brain that has been implicated in mediating cell death induced by oxidants. We found a heterozygous variant of TRPM2 in a subset of Guamanian ALS (ALS-G) and PD (PD-G) cases. This variant, TRPM2(P1018L), produces a missense change in the channel protein whereby proline 1018 (Pro(1018)) is replaced by leucine (Leu(1018)). Functional studies revealed that, unlike WT TRPM2, P1018L channels inactivate. Our results suggest that the ability of TRPM2 to maintain sustained ion influx is a physiologically important function and that its disruption may, under certain conditions, contribute to disease states.
Collapse
|
34
|
Cens T, Leyris JP, Charnet P. Introduction into Cav2.1 of the homologous mutation of Cav1.2 causing the Timothy syndrome questions the role of V421 in the phenotypic definition of P-type Ca2+ channel. Pflugers Arch 2008; 457:417-30. [DOI: 10.1007/s00424-008-0534-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2008] [Revised: 04/17/2008] [Accepted: 05/15/2008] [Indexed: 01/06/2023]
|
35
|
Fox AP, Cahill AL, Currie KPM, Grabner C, Harkins AB, Herring B, Hurley JH, Xie Z. N- and P/Q-type Ca2+ channels in adrenal chromaffin cells. Acta Physiol (Oxf) 2008; 192:247-61. [PMID: 18021320 DOI: 10.1111/j.1748-1716.2007.01817.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Ca2+ is the most ubiquitous second messenger found in all cells. Alterations in [Ca2+]i contribute to a wide variety of cellular responses including neurotransmitter release, muscle contraction, synaptogenesis and gene expression. Voltage-dependent Ca2+ channels, found in all excitable cells (Hille 1992), mediate the entry of Ca2+ into cells following depolarization. Ca2+ channels are composed of a large pore-forming subunit, called the alpha1 subunit, and several accessory subunits. Ten different alpha1 subunit genes have been identified and classified into three families, Ca(v1-3) (Dunlap et al. 1995, Catterall 2000). Each alpha1 gene produces a unique Ca2+ channel. Although chromaffin cells express several different types of Ca2+ channels, this review will focus on the Cav(2.1) and Cav(2.2) channels, also known as P/Q- and N-type respectively (Nowycky et al. 1985, Llinas et al. 1989b, Wheeler et al. 1994). These channels exhibit physiological and pharmacological properties similar to their neuronal counterparts. N-, P/Q and to a lesser extent R-type Ca2+ channels are known to regulate neurotransmitter release (Hirning et al. 1988, Horne & Kemp 1991, Uchitel et al. 1992, Luebke et al. 1993, Takahashi & Momiyama 1993, Turner et al. 1993, Regehr & Mintz 1994, Wheeler et al. 1994, Wu & Saggau 1994, Waterman 1996, Wright & Angus 1996, Reid et al. 1997). N- and P/Q-type Ca2+ channels are abundant in nerve terminals where they colocalize with synaptic vesicles. Similarly, these channels play a role in neurotransmitter release in chromaffin cells (Garcia et al. 2006). N- and P/Q-type channels are subject to many forms of regulation (Ikeda & Dunlap 1999). This review pays particular attention to the regulation of N- and P/Q-type channels by heterotrimeric G-proteins, interaction with SNARE proteins, and channel inactivation in the context of stimulus-secretion coupling in adrenal chromaffin cells.
Collapse
Affiliation(s)
- A P Fox
- Department of Neurobiology, Pharmacology and Physiology, University of Chicago, Chicago, IL 60637, USA.
| | | | | | | | | | | | | | | |
Collapse
|
36
|
Cohen R, Marom M, Atlas D. Depolarization-evoked secretion requires two vicinal transmembrane cysteines of syntaxin 1A. PLoS One 2007; 2:e1273. [PMID: 18060067 PMCID: PMC2094736 DOI: 10.1371/journal.pone.0001273] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2007] [Accepted: 11/14/2007] [Indexed: 11/24/2022] Open
Abstract
Background The interactions of the voltage-gated Ca2+ channel (VGCC) with syntaxin 1A (Sx 1A), Synaptosome-associated protein of 25 kD (SNAP-25), and synaptotagmin, couple electrical excitation to evoked secretion. Two vicinal Cys residues, Cys 271 and Cys 272 in the Sx 1A transmembrane domain, are highly conserved and participate in modulating channel kinetics. Each of the Sx1A Cys mutants, differently modify the kinetics of Cav1.2, and neuronal Cav2.2 calcium channel. Methodology/Principle Findings We examined the effects of various Sx1A Cys mutants and the syntaxin isoforms 2, 3, and 4 each of which lack vicinal Cys residues, on evoked secretion, monitoring capacitance transients in a functional release assay. Membrane capacitance in Xenopus oocytes co-expressing Cav1.2, Sx1A, SNAP-25 and synaptotagmin, which is Bot C- and Bot A-sensitive, was elicited by a double 500 ms depolarizing pulse to 0 mV. The evoked-release was obliterated when a single Cys Sx1A mutant or either one of the Sx isoforms were substituted for Sx 1A, demonstrating the essential role of vicinal Cys residues in the depolarization mediated process. Protein expression and confocal imaging established the level of the mutated proteins in the cell and their targeting to the plasma membrane. Conclusions/Significance We propose a model whereby the two adjacent transmembranal Cys residues of Sx 1A, lash two calcium channels. Consistent with the necessity of a minimal fusion complex termed the excitosome, each Sx1A is in a complex with SNAP-25, Syt1, and the Ca2+ channel. A Hill coefficient >2 imply that at least three excitosome complexes are required for generating a secreting hetero-oligomer protein complex. This working model suggests that a fusion pore that opens during membrane depolarization could be lined by alternating transmembrane segments of Sx1A and VGCC. The functional coupling of distinct amino acids of Sx 1A with VGCC appears to be essential for depolarization-evoked secretion.
Collapse
Affiliation(s)
- Roy Cohen
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Merav Marom
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Daphne Atlas
- Department of Biological Chemistry, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
- * To whom correspondence should be addressed. E-mail:
| |
Collapse
|
37
|
Tian L, Jiang X, Rasmusson R, Wang S. Effect of propafenone on Kv1.4 inactivation. J Physiol Biochem 2007; 62:263-70. [PMID: 17615952 DOI: 10.1007/bf03165755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Interactions between antiarrhythmic drugs and ion channels are important subjects in the field of cardiovascular electro-pharmacology. This study explores the relationship between propafenone and C-type inactivation of Kv1.4 channel. fKvl.4deltaN, a ferret Kv1.4 N-terminal deleted mutant, was employed in this study. fKvl.4deltaN cRNA was injected into Xenopus oocytes to express fKvl.4deltaN channel and two electrode voltage clamp technique was used to record the current. We found that fKvl.4deltaN channel current was rapidly depressed in a frequency-dependent manner and meanwhile, C-type inactivation in this channel was increased more than 7 folds in the presence of 100 microM propafenone. While propafenone has no effect on Kv1.4deltaN recovery. All the results indicate that propafenone blocks Kvl.4deltaN channel through intracellular bindings and that binding of propafenone with Kvl.4deltaN channel leads to a conformational change on the extracellular site which accelerates C-type inactivation, suggesting that propafenone, as an open channel blocker, may affect the mechanism of C-type inactivation.
Collapse
Affiliation(s)
- L Tian
- Department of Cardiology, Renmin Hospital of Wuhan University, 238 Jiefang Road, Wuhan, Hubei, China 430060
| | | | | | | |
Collapse
|
38
|
Kiyonaka S, Wakamori M, Miki T, Uriu Y, Nonaka M, Bito H, Beedle AM, Mori E, Hara Y, De Waard M, Kanagawa M, Itakura M, Takahashi M, Campbell KP, Mori Y. RIM1 confers sustained activity and neurotransmitter vesicle anchoring to presynaptic Ca2+ channels. Nat Neurosci 2007; 10:691-701. [PMID: 17496890 PMCID: PMC2687938 DOI: 10.1038/nn1904] [Citation(s) in RCA: 176] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2007] [Accepted: 04/02/2007] [Indexed: 12/20/2022]
Abstract
The molecular organization of presynaptic active zones is important for the neurotransmitter release that is triggered by depolarization-induced Ca2+ influx. Here, we demonstrate a previously unknown interaction between two components of the presynaptic active zone, RIM1 and voltage-dependent Ca2+ channels (VDCCs), that controls neurotransmitter release in mammalian neurons. RIM1 associated with VDCC beta-subunits via its C terminus to markedly suppress voltage-dependent inactivation among different neuronal VDCCs. Consistently, in pheochromocytoma neuroendocrine PC12 cells, acetylcholine release was significantly potentiated by the full-length and C-terminal RIM1 constructs, but membrane docking of vesicles was enhanced only by the full-length RIM1. The beta construct beta-AID dominant negative, which disrupts the RIM1-beta association, accelerated the inactivation of native VDCC currents, suppressed vesicle docking and acetylcholine release in PC12 cells, and inhibited glutamate release in cultured cerebellar neurons. Thus, RIM1 association with beta in the presynaptic active zone supports release via two distinct mechanisms: sustaining Ca2+ influx through inhibition of channel inactivation, and anchoring neurotransmitter-containing vesicles in the vicinity of VDCCs.
Collapse
Affiliation(s)
- Shigeki Kiyonaka
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
| | - Minoru Wakamori
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
| | - Takafumi Miki
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
| | - Yoshitsugu Uriu
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
| | - Mio Nonaka
- Department of Neurochemistry
University of TokyoUniversity of Tokyo Graduate School of Medicine, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033,JP
| | - Haruhiko Bito
- Department of Neurochemistry
University of TokyoUniversity of Tokyo Graduate School of Medicine, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033,JP
| | - Aaron M. Beedle
- Departments of Physiology and Biophysics, Internal Medicine, and Neurology
University of IowaUniversity of Iowa Roy J. and Lucille A. Carver College of Medicine, 285 Newton Road, Iowa City, Iowa 52242-1101,US
- HHMI, Howard Hughes Medical Institute
Howard Hugues Institute Howard Hughes Medical Institute,US
| | - Emiko Mori
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
| | - Yuji Hara
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
- Departments of Physiology and Biophysics, Internal Medicine, and Neurology
University of IowaUniversity of Iowa Roy J. and Lucille A. Carver College of Medicine, 285 Newton Road, Iowa City, Iowa 52242-1101,US
- HHMI, Howard Hughes Medical Institute
Howard Hugues Institute Howard Hughes Medical Institute,US
| | - Michel De Waard
- Canaux calciques , fonctions et pathologies
INSERM : U607CEA : DSV/IRTSVUniversité Joseph Fourier - Grenoble I17, rue des martyrs 38054 Grenoble,FR
| | - Motoi Kanagawa
- Departments of Physiology and Biophysics, Internal Medicine, and Neurology
University of IowaUniversity of Iowa Roy J. and Lucille A. Carver College of Medicine, 285 Newton Road, Iowa City, Iowa 52242-1101,US
- HHMI, Howard Hughes Medical Institute
Howard Hugues Institute Howard Hughes Medical Institute,US
| | - Makoto Itakura
- Department of Biochemistry
Kitasato University School of MedicineKitasato University School of Medicine, Kitasato 1-15-1, Sagamihara, Kanagawa 228-8555,JP
| | - Masami Takahashi
- Department of Biochemistry
Kitasato University School of MedicineKitasato University School of Medicine, Kitasato 1-15-1, Sagamihara, Kanagawa 228-8555,JP
| | - Kevin P. Campbell
- Departments of Physiology and Biophysics, Internal Medicine, and Neurology
University of IowaUniversity of Iowa Roy J. and Lucille A. Carver College of Medicine, 285 Newton Road, Iowa City, Iowa 52242-1101,US
- HHMI, Howard Hughes Medical Institute
Howard Hugues Institute Howard Hughes Medical Institute,US
| | - Yasuo Mori
- Department of Synthetic Chemistry and Biological Chemistry
Kyoto UniversityGraduate School of Engineering, Kyoto University, Katsura Campus, Nishikyo-ku, Kyoto 615-8510,JP
- * Correspondence should be adressed to: Yasuo Mori
| |
Collapse
|
39
|
Abstract
Triggered activity in cardiac muscle and intracellular Ca2+ have been linked in the past. However, today not only are there a number of cellular proteins that show clear Ca2+ dependence but also there are a number of arrhythmias whose mechanism appears to be linked to Ca2+-dependent processes. Thus we present a systematic review of the mechanisms of Ca2+ transport (forward excitation-contraction coupling) in the ventricular cell as well as what is known for other cardiac cell types. Second, we review the molecular nature of the proteins that are involved in this process as well as the functional consequences of both normal and abnormal Ca2+ cycling (e.g., Ca2+ waves). Finally, we review what we understand to be the role of Ca2+ cycling in various forms of arrhythmias, that is, those associated with inherited mutations and those that are acquired and resulting from reentrant excitation and/or abnormal impulse generation (e.g., triggered activity). Further solving the nature of these intricate and dynamic interactions promises to be an important area of research for a better recognition and understanding of the nature of Ca2+ and arrhythmias. Our solutions will provide a more complete understanding of the molecular basis for the targeted control of cellular calcium in the treatment and prevention of such.
Collapse
Affiliation(s)
- Henk E D J Ter Keurs
- Department of Medicine, Physiology and Biophysics, University of Calgary, Alberta, Canada
| | | |
Collapse
|
40
|
Voltage-gated calcium channels, calcium signaling, and channelopathies. CALCIUM - A MATTER OF LIFE OR DEATH 2007. [DOI: 10.1016/s0167-7306(06)41005-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
|
41
|
Li Y, Wu Y, Zhou Y. Modulation of inactivation properties of CaV2.2 channels by 14-3-3 proteins. Neuron 2006; 51:755-71. [PMID: 16982421 DOI: 10.1016/j.neuron.2006.08.014] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2005] [Revised: 05/08/2006] [Accepted: 08/08/2006] [Indexed: 11/28/2022]
Abstract
Inactivation of presynaptic Ca(V)2.2 channels may play a role in regulating short-term synaptic plasticity. Here, we report a direct modulation of Ca(V)2.2 channel inactivation properties by 14-3-3, a family of signaling proteins involved in a wide range of biological processes. The structural elements critical for 14-3-3 binding and channel modulation lie in the carboxyl tail of the pore-forming alpha(1B) subunit, where we have identified two putative 14-3-3 interaction sites, including a phosphoserine-containing motif that directly binds to 14-3-3 and a second region near the EF hand and IQ domain. In transfected tsA 201 cells, 14-3-3 coexpression dramatically slows open-state inactivation and reduces cumulative inactivation of Ca(V)2.2 channels. In hippocampal neurons, interference with 14-3-3 binding accelerates Ca(V)2.2 channel inactivation and enhances short-term synaptic depression. These results demonstrate that 14-3-3 proteins are important regulators of Ca(V)2.2 channel activities and through this mechanism may contribute to their regulation of synaptic transmission and plasticity.
Collapse
MESH Headings
- 14-3-3 Proteins/genetics
- 14-3-3 Proteins/metabolism
- 14-3-3 Proteins/physiology
- Amino Acid Sequence
- Animals
- Binding Sites/genetics
- Binding, Competitive
- Blotting, Western
- Brain/cytology
- Brain/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Channels, N-Type/genetics
- Calcium Channels, N-Type/metabolism
- Calcium Channels, T-Type/genetics
- Calcium Channels, T-Type/metabolism
- Cell Line
- Cells, Cultured
- Glutathione Transferase/genetics
- Glutathione Transferase/metabolism
- Humans
- Neurons/cytology
- Neurons/metabolism
- Phosphorylation
- Protein Binding
- Protein Subunits/genetics
- Protein Subunits/metabolism
- Rats
- Rats, Sprague-Dawley
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Synaptic Transmission/physiology
- Time Factors
Collapse
Affiliation(s)
- Yong Li
- Department of Neurobiology, Evelyn F. McKnight Brain Institute and Civitan International Research Center, School of Medicine, University of Alabama at Birmingham, 35294, USA
| | | | | |
Collapse
|
42
|
Livneh A, Cohen R, Atlas D. A novel molecular inactivation determinant of voltage-gated CaV1.2 L-type Ca2+ channel. Neuroscience 2006; 139:1275-87. [PMID: 16533566 DOI: 10.1016/j.neuroscience.2006.01.028] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2005] [Revised: 01/26/2006] [Accepted: 01/26/2006] [Indexed: 11/16/2022]
Abstract
The inactivation of voltage-gated L-type Ca(2+) channels (Ca(V)1) regulates Ca(2+) entry and controls intracellular Ca(2+) levels that are essential for cellular activity. The molecular entities implicated in L-channel (Ca(V)1.2) inactivation are not fully identified. Here we show for the first time the functional impact of one of the two highly conserved clusters of six negatively charged glutamates and aspartate (802-807; poly ED motif) at the II-III loop of the alpha 1 subunits of rabbit of Ca(v)1.2, alpha(1)1.2 and alpha(1)1.2 DeltaN60-Delta1733) on voltage-dependent inactivation. Mutation of the poly ED motif to alanine or glutamine/asparagine greatly enhanced voltage-dependent inactivation, shifting the voltage dependence to negative potentials by >50 mV and conferring a neuronal like inactivation kinetics onto Ca(V)1.2. The large shift in the midpoint of inactivation of the steady-state inactivation kinetics was observed also in Ca(2+) or Ba(2+) and was not altered by the beta2A subunit. Missing from the fast inactivating neuronal P/Q (Ca(V)2.1)-, N (Ca(V)2.2)- or R (Ca(V)2.3)-type channels and modulating Ca(V)1.2 inactivation kinetics, the poly ED motif is likely to be a specific L-type Ca(2+) channels inactivating domain. Our results fit a model in which the poly ED either by itself or as part of a larger inactivating motif acts as Ca(V)1.2 specific built-in "stopper." In this model, Ca(V)1 accomplishes a large Ca(2+) influx during depolarization, possibly by the poly ED hindering occlusion at the pore. Furthermore, the selective designed poly ED perhaps clarifies major inactivation differences between L- and non-L-type calcium channels.
Collapse
Affiliation(s)
- A Livneh
- Department of Biological Chemistry, The Silverman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | | | | |
Collapse
|
43
|
Sonkusare S, Palade PT, Marsh JD, Telemaque S, Pesic A, Rusch NJ. Vascular calcium channels and high blood pressure: pathophysiology and therapeutic implications. Vascul Pharmacol 2006; 44:131-42. [PMID: 16427812 PMCID: PMC4917380 DOI: 10.1016/j.vph.2005.10.005] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2005] [Accepted: 10/05/2005] [Indexed: 10/25/2022]
Abstract
Long-lasting Ca(2+) (Ca(L)) channels of the Ca(v)1.2 gene family are heteromultimeric structures that are minimally composed of a pore-forming alpha(1C) subunit and regulatory beta and alpha(2)delta subunits in vascular smooth muscle cells. The Ca(L) channels are the primary pathways for voltage-gated Ca(2+) influx that trigger excitation-contraction coupling in small resistance vessels. Notably, vascular smooth muscle cells of hypertensive rats show an increased expression of Ca(L) channel alpha(1C) subunits, which is associated with elevated Ca(2+) influx and the development of abnormal arterial tone. Indeed, blood pressure per se appears to promote Ca(L) channel expression in small arteries, and even short-term rises in pressure may alter channel expression. Membrane depolarization has been shown to be one stimulus associated with elevated blood pressure that promotes Ca(L) channel expression at the plasma membrane. Future studies to define the molecular processes that regulate Ca(L) channel expression in vascular smooth muscle cells will provide a rational basis for designing antihypertensive therapies to normalize Ca(L) channel expression and the development of anomalous vascular tone in hypertensive pathologies.
Collapse
Affiliation(s)
- Swapnil Sonkusare
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, #611 Little Rock, AR 72205-7199, United States
| | - Philip T. Palade
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, #611 Little Rock, AR 72205-7199, United States
| | - James D. Marsh
- Department of Internal Medicine, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205-7199, United States
| | - Sabine Telemaque
- Department of Internal Medicine, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205-7199, United States
| | - Aleksandra Pesic
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, #611 Little Rock, AR 72205-7199, United States
| | - Nancy J. Rusch
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, 4301 West Markham Street, #611 Little Rock, AR 72205-7199, United States
- Corresponding author. Tel.: +1 501 686 8038; fax: +1 501 686 5521. (N.J. Rusch)
| |
Collapse
|
44
|
Boyden PA, ter Keurs H. Would modulation of intracellular Ca2+ be antiarrhythmic? Pharmacol Ther 2005; 108:149-79. [PMID: 16038982 DOI: 10.1016/j.pharmthera.2005.03.011] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2005] [Accepted: 03/22/2005] [Indexed: 01/10/2023]
Abstract
Under several types of conditions, reversal of steps of excitation-contraction coupling (RECC) can give rise to nondriven electrical activity. In this review we explore those conditions for several cardiac cell types (SA, atrial, Purkinje, ventricular cells). We find that abnormal spontaneous Ca2+ release from intracellular Ca2+ stores, aberrant Ca2+ influx from sarcolemmal channels or abnormal Ca2+ surges in nonuniform muscle can be the initiators of the RECC. Often, with such increases in Ca2+, spontaneous Ca2+ waves occur and lead to membrane depolarizations. Because the change in membrane voltage is produced by Ca2+-dependent changes in ion channel function, we also review here what is known about the molecular interaction of Ca2+ and several Ca2+-dependent processes, including the intracellular Ca2+ release channels implicated in the genetic basis of some forms of human arrhythmias. Finally, we review what is known about the effectiveness of several agents in modifying such Ca2+-dependent arrhythmias.
Collapse
Affiliation(s)
- Penelope A Boyden
- Department of Pharmacology, Center for Molecular Therapeutics, Columbia University, NY 10032, USA.
| | | |
Collapse
|
45
|
Winquist RJ, Pan JQ, Gribkoff VK. Use-dependent blockade of Cav2.2 voltage-gated calcium channels for neuropathic pain. Biochem Pharmacol 2005; 70:489-99. [PMID: 15950195 DOI: 10.1016/j.bcp.2005.04.035] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2005] [Revised: 04/11/2005] [Accepted: 04/11/2005] [Indexed: 11/28/2022]
Abstract
The translocation of extracellular calcium (Ca(2+)) via voltage-gated Ca(2+) channels (VGCCs) in neurons is involved in triggering multiple physiological cell functions but also the abnormal, pathophysiological responses that develop as a consequence of injury. In conditions of neuropathic pain, VGCCs are involved in supplying the signal Ca(2+) important for the sustained neuronal firing and neurotransmitter release characteristic of these syndromes. Preclinical data have identified N-type VGCCs (Ca(v)2.2) as key participants in contributing to these Ca(2+) signaling events and clinical data with the peptide blocker Prialt have now validated Ca(v)2.2 as a bona fide target for future drug discovery efforts to identify new and novel therapeutics for neuropathic pain. Imperative for the success of such an endeavor will be the ability to identify compounds selective for Ca(v)2.2, versus other VGCCs, but also compounds which demonstrate effective blockade during the pathophysiological states of neuropathic pain without compromising channel activity associated with sustaining normal housekeeping cellular functions. An approach to obtain this research target profile is to identify compounds, which are more potent in blocking Ca(v)2.2 during higher frequencies of firing as compared to the slower more physiologically-relevant frequencies. This may be achieved by identifying compounds with enhanced potency for the inactivated state of Ca(v)2.2. This commentary explores the rationale and options for engineering a use-dependent blocker of Ca(v)2.2. It is anticipated that this use-dependent profile of channel blockade will result in new chemical entities with an improved therapeutic ratio for neuropathic pain.
Collapse
Affiliation(s)
- Raymond J Winquist
- Department of Pharmacology, Scion Pharmaceuticals Inc., 200 Boston Avenue, Suite 3600, Medford, MA 02155, USA.
| | | | | |
Collapse
|
46
|
Li J, Stevens L, Wray D. Molecular regions underlying the activation of low- and high-voltage activating calcium channels. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2005; 34:1017-29. [PMID: 15924245 DOI: 10.1007/s00249-005-0487-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2005] [Accepted: 04/06/2005] [Indexed: 11/29/2022]
Abstract
We have studied two aspects of calcium channel activation. First, we investigated the molecular regions that are important in determining differences in activation between low- and high-voltage activated channels. For this, we made chimeras between the low-voltage activating Ca(V)3.1 channel and the high-voltage activating Ca(V)1.2 channel. Chimeras were expressed in oocytes, and calcium channel currents recorded by voltage clamp. For domain I, we found that the molecular region that is important in determining the voltage dependence of activation comprises the pore regions S5-P as well as P-S6, but surprisingly not the voltage sensor S1-S4 region, which might have been expected to play a major part. By contrast, the smaller, but still significant, modulating effects of domain II on activation properties were due to effects involving both S1-S4 and S5-S6 but not the I/II linker. Second, during channel activation we studied movement of the S4 segment in domain I of one of the chimeras, using cysteine-scanning mutagenesis. The reagent parachloromercuribenzensulfonate inhibited currents for mutants V263, A265, L266 and A268, but not for F269 and V271, and voltage dependence of inhibition for residue V263 indicated S4 movement, which occurred before channel opening. The data indicate movement outwards upon depolarisation so as to expose amino acids up to residue 268 in S4.
Collapse
Affiliation(s)
- Junying Li
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
| | | | | |
Collapse
|
47
|
Benoff S, Goodwin LO, Millan C, Hurley IR, Pergolizzi RG, Marmar JL. Deletions in L-type calcium channel α1 subunit testicular transcripts correlate with testicular cadmium and apoptosis in infertile men with varicoceles. Fertil Steril 2005; 83:622-34. [PMID: 15749491 DOI: 10.1016/j.fertnstert.2004.07.976] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2004] [Revised: 07/30/2004] [Accepted: 07/30/2004] [Indexed: 10/25/2022]
Abstract
OBJECTIVE To identify and understand predictors of successful varicocelectomy. DESIGN Examination of testicular L-type voltage-dependent calcium channel (L-VDCC) mRNAs and proteins in testis biopsies and comparison of presence and absence of various mRNAs with testicular cadmium levels, with apoptosis, and with sperm count change after varicocelectomy. SETTING University clinical urology practice and research laboratories. PATIENT(S) Infertile men with varicocele (left varicocele only, n = 18; bilateral varicoceles, n = 26) and controls (men with obstructive azoospermia undergoing testicular sperm extraction before intracytoplasmic sperm injection; n = 7). INTERVENTION(S) Left testis biopsies by percutaneous needle aspiration biopsy. Varicocele repair by subinguinal approach. MAIN OUTCOME MEASURE(S) Calcium channel mRNA sequence by reverse transcription-polymerase chain reaction and amplicon analysis; calcium channel protein distribution by immunocytochemistry; cadmium levels by atomic absorption and apoptosis by deoxynucleotidyl transferase labeling; and sperm counts in the ejaculate before and after varicocelectomy. RESULT(S) Calcium channel mRNAs are polymorphic in human testis biopsies from different men. Proteins from sequence-deleted exons 7 and/or 8 localize to germ cell membranes. Expression of undeleted L-type calcium channel mRNAs correlates with normal testes cadmium and increased sperm count after varicocelectomy. Apoptosis is lower in such cases. CONCLUSION(S) Expression of normal testicular L-VDCC sequence in exons 7-8 predicts postvaricocelectomy sperm count increase. Deletions may alter calcium channel function and affect testicular cadmium and apoptosis.
Collapse
Affiliation(s)
- Susan Benoff
- Fertility Research Laboratories, North Shore-Long Island Jewish Research Institute, North Shore University Hospital, Manhasset, New York, USA
| | | | | | | | | | | |
Collapse
|
48
|
Kochegarov AA. Therapeutical application of voltage-gated calcium channel modulators. Expert Opin Ther Pat 2005. [DOI: 10.1517/13543776.12.2.243] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
49
|
Isaev D, Solt K, Gurtovaya O, Reeves JP, Shirokov R. Modulation of the voltage sensor of L-type Ca2+ channels by intracellular Ca2+. ACTA ACUST UNITED AC 2004; 123:555-71. [PMID: 15111645 PMCID: PMC2234499 DOI: 10.1085/jgp.200308876] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Both intracellular calcium and transmembrane voltage cause inactivation, or spontaneous closure, of L-type (CaV1.2) calcium channels. Here we show that long-lasting elevations of intracellular calcium to the concentrations that are expected to be near an open channel (>/=100 microM) completely and reversibly blocked calcium current through L-type channels. Although charge movements associated with the opening (ON) motion of the channel's voltage sensor were not altered by high calcium, the closing (OFF) transition was impeded. In two-pulse experiments, the blockade of calcium current and the reduction of gating charge movements available for the second pulse developed in parallel during calcium load. The effect depended steeply on voltage and occurred only after a third of the total gating charge had moved. Based on that, we conclude that the calcium binding site is located either in the channel's central cavity behind the voltage-dependent gate, or it is formed de novo during depolarization through voltage-dependent rearrangements just preceding the opening of the gate. The reduction of the OFF charge was due to the negative shift in the voltage dependence of charge movement, as previously observed for voltage-dependent inactivation. Elevation of intracellular calcium concentration from approximately 0.1 to 100-300 microM sped up the conversion of the gating charge into the negatively distributed mode 10-100-fold. Since the "IQ-AA" mutant with disabled calcium/calmodulin regulation of inactivation was affected by intracellular calcium similarly to the wild-type, calcium/calmodulin binding to the "IQ" motif apparently is not involved in the observed changes of voltage-dependent gating. Although calcium influx through the wild-type open channels does not cause a detectable negative shift in the voltage dependence of their charge movement, the shift was readily observable in the Delta1733 carboxyl terminus deletion mutant, which produces fewer nonconducting channels. We propose that the opening movement of the voltage sensor exposes a novel calcium binding site that mediates inactivation.
Collapse
Affiliation(s)
- Dmytro Isaev
- Department of Pharmacology and Physiology, New Jersey Medical School, UMDNJ, 185 South Orange Avenue, Newark, NJ 07101-1709, USA
| | | | | | | | | |
Collapse
|
50
|
Splawski I, Timothy KW, Sharpe LM, Decher N, Kumar P, Bloise R, Napolitano C, Schwartz PJ, Joseph RM, Condouris K, Tager-Flusberg H, Priori SG, Sanguinetti MC, Keating MT. CaV1.2 Calcium Channel Dysfunction Causes a Multisystem Disorder Including Arrhythmia and Autism. Cell 2004; 119:19-31. [PMID: 15454078 DOI: 10.1016/j.cell.2004.09.011] [Citation(s) in RCA: 1082] [Impact Index Per Article: 54.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Revised: 08/09/2004] [Accepted: 08/17/2004] [Indexed: 11/25/2022]
Abstract
Ca(V)1.2, the cardiac L-type calcium channel, is important for excitation and contraction of the heart. Its role in other tissues is unclear. Here we present Timothy syndrome, a novel disorder characterized by multiorgan dysfunction including lethal arrhythmias, webbing of fingers and toes, congenital heart disease, immune deficiency, intermittent hypoglycemia, cognitive abnormalities, and autism. In every case, Timothy syndrome results from the identical, de novo Ca(V)1.2 missense mutation G406R. Ca(V)1.2 is expressed in all affected tissues. Functional expression reveals that G406R produces maintained inward Ca(2+) currents by causing nearly complete loss of voltage-dependent channel inactivation. This likely induces intracellular Ca(2+) overload in multiple cell types. In the heart, prolonged Ca(2+) current delays cardiomyocyte repolarization and increases risk of arrhythmia, the ultimate cause of death in this disorder. These discoveries establish the importance of Ca(V)1.2 in human physiology and development and implicate Ca(2+) signaling in autism.
Collapse
MESH Headings
- Abnormalities, Multiple/genetics
- Abnormalities, Multiple/physiopathology
- Action Potentials/genetics
- Animals
- Arrhythmias, Cardiac/complications
- Arrhythmias, Cardiac/genetics
- Arrhythmias, Cardiac/physiopathology
- Autistic Disorder/complications
- Autistic Disorder/genetics
- Autistic Disorder/physiopathology
- Brain/metabolism
- Brain/physiopathology
- Brain Chemistry/genetics
- CHO Cells
- Calcium/metabolism
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Calcium Signaling/genetics
- Cell Membrane/genetics
- Cell Membrane/metabolism
- Child
- Cricetinae
- Female
- Genetic Diseases, Inborn/complications
- Genetic Diseases, Inborn/genetics
- Genetic Diseases, Inborn/physiopathology
- Heart/physiopathology
- Humans
- Infant, Newborn
- Limb Deformities, Congenital/complications
- Limb Deformities, Congenital/genetics
- Male
- Mice
- Mutation, Missense/genetics
- Myocytes, Cardiac/metabolism
- Neurons/metabolism
- Oocytes
- Pedigree
- Syndrome
- Xenopus laevis
Collapse
Affiliation(s)
- Igor Splawski
- Department of Cardiology, Children's Hospital, Harvard Medical School and Howard Hughes Medical Institute, Boston, MA 02115, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|