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Page DA, Ruben PC. Cannabidiol potentiates hyperpolarization-activated cyclic nucleotide-gated (HCN4) channels. J Gen Physiol 2024; 156:e202313505. [PMID: 38652080 PMCID: PMC11040500 DOI: 10.1085/jgp.202313505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 03/15/2024] [Accepted: 04/09/2024] [Indexed: 04/25/2024] Open
Abstract
Cannabidiol (CBD), the main non-psychotropic phytocannabinoid produced by the Cannabis sativa plant, blocks a variety of cardiac ion channels. We aimed to identify whether CBD regulated the cardiac pacemaker channel or the hyperpolarization-activated cyclic nucleotide-gated channel (HCN4). HCN4 channels are important for the generation of the action potential in the sinoatrial node of the heart and increased heart rate in response to β-adrenergic stimulation. HCN4 channels were expressed in HEK 293T cells, and the effect of CBD application was examined using a whole-cell patch clamp. We found that CBD depolarized the V1/2 of activation in holo-HCN4 channels, with an EC50 of 1.6 µM, without changing the current density. CBD also sped activation kinetics by approximately threefold. CBD potentiation of HCN4 channels occurred via binding to the closed state of the channel. We found that CBD's mechanism of action was distinct from cAMP, as CBD also potentiated apo-HCN4 channels. The addition of an exogenous PIP2 analog did not alter the ability of CBD to potentiate HCN4 channels, suggesting that CBD also acts using a unique mechanism from the known HCN4 potentiator PIP2. Lastly, to gain insight into CBD's mechanism of action, computational modeling and targeted mutagenesis were used to predict that CBD binds to a lipid-binding pocket at the C-terminus of the voltage sensor. CBD represents the first FDA-approved drug to potentiate HCN4 channels, and our findings suggest a novel starting point for drug development targeting HCN4 channels.
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Affiliation(s)
- Dana A. Page
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
| | - Peter C. Ruben
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, Canada
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Uygun DS, Basheer R. Circuits and components of delta wave regulation. Brain Res Bull 2022; 188:223-232. [PMID: 35738502 DOI: 10.1016/j.brainresbull.2022.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/07/2022] [Accepted: 06/14/2022] [Indexed: 11/02/2022]
Abstract
Sleep is vital and the deepest stages of sleep occur within Non-rapid-eye-movement sleep (NREM), defined by high electroencephalographic power in the delta (~0.5-4Hz) wave frequency range. Delta waves are thought to facilitate a myriad of physical and mental health functions. This review aims to comprehensively cover the historical and recent advances in the understanding of the mechanisms orchestrating NREM delta waves. We discuss a complete neurocircuit - focusing on one leg of the circuit at a time - and delve deeply into the molecular mechanistic components that contribute to NREM delta wave regulation. We also discuss the relatively localized nature in which these mechanisms have been defined, and how likely they might generalize across distinct sensory and higher order modalities in the brain.
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Affiliation(s)
- David S Uygun
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA; 02132.
| | - Radhika Basheer
- VA Boston Healthcare System and Harvard Medical School, Dept. of Psychiatry, West Roxbury, MA; 02132.
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Hoekstra M, van Ginneken ACG, Wilders R, Verkerk AO. HCN4 current during human sinoatrial node-like action potentials. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:105-118. [PMID: 34153331 DOI: 10.1016/j.pbiomolbio.2021.05.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/07/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022]
Abstract
BACKGROUND Despite the many studies carried out over the past 40 years, the contribution of the HCN4 encoded hyperpolarization-activated 'funny' current (If) to pacemaker activity in the mammalian sinoatrial node (SAN), and the human SAN in particular, is still controversial and not fully established. OBJECTIVE To study the contribution of If to diastolic depolarization of human SAN cells and its dependence on heart rate, cAMP levels, and atrial load. METHODS HCN4 channels were expressed in human cardiac myocyte progenitor cells (CMPCs) and HCN4 currents assessed using perforated patch-clamp in traditional voltage clamp mode and during action potential clamp with human SAN-like action potential waveforms with 500-1500 ms cycle length, in absence or presence of forskolin to mimic β-adrenergic stimulation and a -15 mV command potential offset to mimic atrial load. RESULTS Forskolin significantly increased the fully-activated HCN4 current density at -140 mV by 14% and shifted the steady-state activation curve by +7.4 mV without affecting its slope. In addition, forskolin significantly accelerated current activation but slowed deactivation. The HCN4 current did not completely deactivate before the subsequent diastolic depolarization during action potential clamp. The amplitude of HCN4 current increased with increasing cycle length, was significantly larger in the presence of forskolin at all cycle lengths, and was significantly increased upon the negative offset to the command potential. CONCLUSIONS If is active during a human SAN action potential waveform and its amplitude is modulated by heart rate, β-adrenergic stimulation, and diastolic voltage range, such that If is under delicate control.
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Affiliation(s)
- Maaike Hoekstra
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Antoni C G van Ginneken
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
| | - Ronald Wilders
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.
| | - Arie O Verkerk
- Department of Medical Biology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands; Department of Experimental Cardiology, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands
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Luo X, Li H, Sun X, Zuo Q, Li B, Zhu Y, Wei W, Gu X. Promotion of Differentiating Bone Marrow Mesenchymal Stromal Cells (BMSCs) into Cardiomyocytes via HCN2 and HCN4 Cotransfection. BIOMED RESEARCH INTERNATIONAL 2021; 2021:5529276. [PMID: 34095298 PMCID: PMC8140823 DOI: 10.1155/2021/5529276] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 03/22/2021] [Accepted: 04/12/2021] [Indexed: 12/03/2022]
Abstract
AIM Investigation of the influences HCN2 and HCN4 has on bone marrow mesenchymal stromal cells (BMSCs) on cardiomyocyte differentiation. METHODS Miniature adult pigs were used for bone marrow extraction and isolation of BMSCs. The identification of these BMSCs was done by using flow cytometry for the detection of expressed surface antigens CD45, CD11B, CD44, and CD90. Using HCN2 and HCN4 genes cotransfected into BMSCs as group HCN2+HCN4 while myocardial induction solution was used to induced BMSC differentiation in the BMSC induction group. Myocardial marker proteins α-actin and cTnT were detected by immunofluorescence staining, while α-actin, cTnT, and Desmin myocardial marker proteins expressed were detected by Western blot. The whole-cell patch-clamp technique was used to identify and detect cellular HCN2 channels, HCN4 channel current activation curve, and the inhibitory effect of CsCl on heterologous expression currents. RESULTS Flow cytometry results showed that CD45 and CD11B were expressed negatively while CD90 and CD44 were positive. Post HCN2 and HCN4 gene transfection, immunofluorescence staining, and Western blot showed significantly increased HCN2, HCN4, α-actin, and cTnT expressed in group HCN2+HCN4 were, which could be compared to the expression levels in the BMSC-induced group. The HCN2+HCN4 group was able to document cell membrane channel ion currents that were similar to If properties. CONCLUSION HCN2 and HCN4 overexpression can considerably enhance the MSC ability to differentiate into cardiomyocytes in vitro and restore the ionic current.
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Affiliation(s)
- Xue Luo
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Pathology, Medical College of Yangzhou Polytechnic College, Yangzhou, Jiangsu 225009, China
| | - Hongxiao Li
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Cardiology, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu 225001, China
| | - Xiaolin Sun
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Cardiology, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu 225001, China
| | - Qisheng Zuo
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225001, China
| | - Bichun Li
- College of Animal Science and Technology, Yangzhou University, Yangzhou, Jiangsu 225001, China
| | - Ye Zhu
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Cardiology, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu 225001, China
| | - Wei Wei
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Cardiology, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu 225001, China
| | - Xiang Gu
- Medical College of Yangzhou University, Yangzhou, Jiangsu 225001, China
- Department of Cardiology, Northern Jiangsu People's Hospital, Yangzhou, Jiangsu 225001, China
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Chen C, Liu L, Shu YQ, Jing P, Lu Y, Zhang XX, Zong XG, Guo LJ, Li CJ. Blockade of HCN2 Channels Provides Neuroprotection Against Ischemic Injury via Accelerating Autophagic Degradation in Hippocampal Neurons. Neurosci Bull 2020; 36:875-894. [PMID: 32519067 PMCID: PMC7410947 DOI: 10.1007/s12264-020-00513-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2019] [Accepted: 02/16/2020] [Indexed: 01/25/2023] Open
Abstract
In the central nervous system, hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are essential to maintain normal neuronal function. Recent studies have shown that HCN channels may be involved in the pathological process of ischemic brain injury, but the mechanisms remain unclear. Autophagy is activated in cerebral ischemia, but its role in cell death/survival remains controversial. In this study, our results showed that the HCN channel blocker ZD7288 remarkably decreased the percentage of apoptotic neurons and corrected the excessive autophagy induced by oxygen-glucose deprivation followed by reperfusion (OGD/R) in hippocampal HT22 neurons. Furthermore, in the OGD/R group, p-mTOR, p-ULK1 (Ser757), and p62 were significantly decreased, while p-ULK1 (Ser317), atg5, and beclin1 were remarkably increased. ZD7288 did not change the expression of p-ULK1 (Ser757), ULK1 (Ser317), p62, Beclin1, and atg5, which are involved in regulating autophagosome formation. Besides, we found that OGD/R induced a significant increase in Cathepsin D expression, but not LAMP-1. Treatment with ZD7288 at 10 μmol/L in the OGD/R group did not change the expression of cathepsin D and LAMP-1. However, chloroquine (CQ), which decreases autophagosome-lysosome fusion, eliminated the correction of excessive autophagy and neuroprotection by ZD7288. Besides, shRNA knockdown of HCN2 channels significantly reduced the accumulation of LC3-II and increased neuron survival in the OGD/R and transient global cerebral ischemia (TGCI) models, and CQ also eliminated the effects of HCN2-shRNA. Furthermore, we found that the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes decreased in Con-shRNA-transfected HT22 neurons exposed to OGD/R or CQ. In HCN2-shRNA-transfected HT22 neurons, the percentage of LC3-positive puncta that co-localized with LAMP-1-positive lysosomes increased under OGD/R; however, the percentage was significantly decreased by the addition of CQ to HCN2-shRNA-transfected HT22 neurons. The present results demonstrated that blockade of HCN2 channels provides neuroprotection against OGD/R and TGCI by accelerating autophagic degradation attributable to the promotion of autophagosome and lysosome fusion.
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Affiliation(s)
- Cheng Chen
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Li Liu
- Office of Academic Research, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ya-Qiao Shu
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Ping Jing
- Department of Neurology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yun Lu
- Department of Pharmacy, Zhongnan Hospital of Wuhan University, Wuhan, 430030, China
| | - Xiao-Xue Zhang
- Department of Clinical Laboratory, Wuhan PuAi Hospital, Wuhan, 430033, China
| | - Xian-Gang Zong
- Center for Integrated Protein Science and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 80539, Munich, Germany
| | - Lian-Jun Guo
- Department of Pharmacology, School of Basic Medical Sciences, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
- Key Laboratory of Drug Target Research and Pharmacodynamic Evaluation, Wuhan, 430030, China.
| | - Chang-Jun Li
- Department of Neurology, The Central Hospital of Wuhan, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
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Günther A, Luczak V, Gruteser N, Abel T, Baumann A. HCN4 knockdown in dorsal hippocampus promotes anxiety-like behavior in mice. GENES BRAIN AND BEHAVIOR 2019; 18:e12550. [PMID: 30585408 PMCID: PMC6850037 DOI: 10.1111/gbb.12550] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 12/03/2018] [Accepted: 12/22/2018] [Indexed: 12/29/2022]
Abstract
Hyperpolarization‐activated and cyclic nucleotide‐gated (HCN) channels mediate the Ih current in the murine hippocampus. Disruption of the Ih current by knockout of HCN1, HCN2 or tetratricopeptide repeat‐containing Rab8b‐interacting protein has been shown to affect physiological processes such as synaptic integration and maintenance of resting membrane potentials as well as several behaviors in mice, including depressive‐like and anxiety‐like behaviors. However, the potential involvement of the HCN4 isoform in these processes is unknown. Here, we assessed the contribution of the HCN4 isoform to neuronal processing and hippocampus‐based behaviors in mice. We show that HCN4 is expressed in various regions of the hippocampus, with distinct expression patterns that partially overlapped with other HCN isoforms. For behavioral analysis, we specifically modulated HCN4 expression by injecting recombinant adeno‐associated viral (rAAV) vectors mediating expression of short hairpin RNA against hcn4 (shHcn4) into the dorsal hippocampus of mice. HCN4 knockdown produced no effect on contextual fear conditioning or spatial memory. However, a pronounced anxiogenic effect was evident in mice treated with shHcn4 compared to control littermates. Our findings suggest that HCN4 specifically contributes to anxiety‐like behaviors in mice.
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Affiliation(s)
- Anne Günther
- Laboratory for Synaptic Molecules of Memory Persistence, Center for Brain Science, RIKEN, Saitama, Japan.,Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Vincent Luczak
- Division of Biological Sciences and Center for Neural Circuits and Behavior, Neurobiology Section, Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, California, USA
| | - Nadine Gruteser
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Ted Abel
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Arnd Baumann
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
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Zhong P, Vickstrom CR, Liu X, Hu Y, Yu L, Yu HG, Liu QS. HCN2 channels in the ventral tegmental area regulate behavioral responses to chronic stress. eLife 2018; 7:32420. [PMID: 29256865 PMCID: PMC5749952 DOI: 10.7554/elife.32420] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2017] [Accepted: 12/18/2017] [Indexed: 12/17/2022] Open
Abstract
Dopamine neurons in the ventral tegmental area (VTA) are powerful regulators of depression-related behavior. Dopamine neuron activity is altered in chronic stress-based models of depression, but the underlying mechanisms remain incompletely understood. Here, we show that mice subject to chronic mild unpredictable stress (CMS) exhibit anxiety- and depressive-like behavior, which was associated with decreased VTA dopamine neuron firing in vivo and ex vivo. Dopamine neuron firing is governed by voltage-gated ion channels, in particular hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. Following CMS, HCN-mediated currents were decreased in nucleus accumbens-projecting VTA dopamine neurons. Furthermore, shRNA-mediated HCN2 knockdown in the VTA was sufficient to recapitulate CMS-induced depressive- and anxiety-like behavior in stress-naïve mice, whereas VTA HCN2 overexpression largely prevented CMS-induced behavioral deficits. Together, these results reveal a critical role for HCN2 in regulating VTA dopamine neuronal activity and depressive-related behaviors.
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Affiliation(s)
- Peng Zhong
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
| | - Casey R Vickstrom
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
| | - Xiaojie Liu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
| | - Ying Hu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
| | - Laikang Yu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
| | - Han-Gang Yu
- Department of Physiology and Pharmacology, West Virginia University, Morgantown, United States
| | - Qing-Song Liu
- Department of Pharmacology and Toxicology, Medical College of Wisconsin, Milwaukee, United States
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Du J, Deng S, Pu D, Liu Y, Xiao J, She Q. Age-dependent down-regulation of hyperpolarization-activated cyclic nucleotide-gated channel 4 causes deterioration of canine sinoatrial node function. Acta Biochim Biophys Sin (Shanghai) 2017; 49:400-408. [PMID: 28369243 DOI: 10.1093/abbs/gmx026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2016] [Indexed: 12/19/2022] Open
Abstract
The activity of pacemaker cells in the sinoatrial node (SAN) is an indicator of normal sinus rhythm. Clinical studies have revealed that the dysfunction of the SAN progressively increases with aging. In this study, we determined the changes in hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) expression and the relationship between aging and canine SAN dysfunction. The results of cardiac electrophysiological determination revealed that the intrinsic heart rate decreased from 168 ± 11 beats min-1 in young canines to 120 ± 9 beats min-1 in adults and to 88 ± 9 beats min-1 in aged canines. The sinus node recovery time (SNRT) increased from 412 ± 32 ms in young canines to 620 ± 56 ms in adults and to 838 ± 120 ms in aged canines. Corrected SNRT (CSNRT) increased from 55 ± 12 ms in young canines to 117 ± 27 ms in adults and to 171 ± 37 ms in aged canines. These results indicated that SAN function deteriorated with aging in the canine heart. However, histological staining illustrated that fibrosis was not significantly increased with aging in canine SAN. Real-time polymerase chain reaction indicated that the expression of HCN4 mRNA was downregulated in the elderly canine SAN. Similarly, we also verified that HCN4 protein expression within the SAN declined with aging via immunofluorescence staining and western blot analysis. Taken together, our data show that electrical remodeling, related to the down-regulation of HCN4, is responsible for the gradually increased incidence of SAN dysfunction with aging. Our results provide further evidence for explaining the mechanisms of age-related deterioration in the SAN.
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Affiliation(s)
- Jianlin Du
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
| | - Songbai Deng
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
| | - Di Pu
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
| | - Yajie Liu
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
| | - Jun Xiao
- Department of Cardiology, Chongqing Medical Emergency Center, Chongqing 400014, China
| | - Qiang She
- Department of Cardiology, The Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China
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Tibbs GR, Posson DJ, Goldstein PA. Voltage-Gated Ion Channels in the PNS: Novel Therapies for Neuropathic Pain? Trends Pharmacol Sci 2016; 37:522-542. [DOI: 10.1016/j.tips.2016.05.002] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/24/2016] [Accepted: 05/03/2016] [Indexed: 12/19/2022]
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Decreased HCN2 expression in STN contributes to abnormal high-voltage spindles in the cortex and globus pallidus of freely moving rats. Brain Res 2015; 1618:17-28. [DOI: 10.1016/j.brainres.2015.05.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Revised: 05/06/2015] [Accepted: 05/08/2015] [Indexed: 12/23/2022]
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Günther A, Baumann A. Distinct expression patterns of HCN channels in HL-1 cardiomyocytes. BMC Cell Biol 2015; 16:18. [PMID: 26141616 PMCID: PMC4490601 DOI: 10.1186/s12860-015-0065-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 06/05/2015] [Indexed: 01/05/2023] Open
Abstract
Background Cardiac rhythmic activity is initiated in functionally specialized areas of the heart. Hyperpolarization-activated and cyclic nucleotide-gated (HCN) channels are fundamental for these processes of cardiac physiology. Results Here we investigated transcript and protein expression patterns of HCN channels in HL-1 cardiomyocytes using a combination of quantitative PCR analysis and immunocytochemistry. Gene expression profiles of hcn1, hcn2 and hcn4 were acutely affected during HL-1 cell propagation. In addition, distinct expression patterns were uncovered for HCN1, HCN2 and HCN4 proteins. Conclusions Our results suggest that HCN channel isoforms might be involved in the concerted differentiation of HL-1 cells and may indirectly affect the occurrence of contractile HL-1 cell activity. We expect that these findings will promote studies on other molecular markers that contribute to cardiac physiology. Electronic supplementary material The online version of this article (doi:10.1186/s12860-015-0065-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Anne Günther
- Institute of Complex Systems, Cellular Biophysics (ICS-4), Wilhelm-Johnen-Straße, Forschungszentrum Jülich, D-52425, Jülich, Germany.
| | - Arnd Baumann
- Institute of Complex Systems, Cellular Biophysics (ICS-4), Wilhelm-Johnen-Straße, Forschungszentrum Jülich, D-52425, Jülich, Germany.
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Rivera-Meza M, Quintanilla ME, Bustamante D, Delgado R, Buscaglia M, Herrera-Marschitz M. Overexpression of hyperpolarization-activated cyclic nucleotide-gated channels into the ventral tegmental area increases the rewarding effects of ethanol in UChB drinking rats. Alcohol Clin Exp Res 2014; 38:911-20. [PMID: 24460767 DOI: 10.1111/acer.12344] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2013] [Accepted: 11/27/2013] [Indexed: 11/30/2022]
Abstract
BACKGROUND A number of studies have shown that ethanol (EtOH) activates dopamine neurocircuitries and is self-administered into the ventral tegmental area (VTA) of the rat brain. In vitro and in silico studies have showed that hyperpolarization-activated cyclic nucleotide-gated (HCN) ionic channels on VTA dopamine neurons may constitute a molecular target of EtOH; however, there is no in vivo evidence supporting this assumption. METHODS Wistar-derived University of Chile Drinking (UChB) rats were microinjected into the VTA with a lentiviral vector coding for rat HCN-2 ionic channel or a control vector. Four days after vector administration, daily voluntary EtOH intake was assessed for 30 days under a free-access paradigm to 5% EtOH and water. After EtOH consumption studies, the effect of HCN-2 overexpression was also assessed on EtOH-induced conditioned place preference (CPP); EtOH-induced locomotion, and EtOH-induced dopamine release in the nucleus accumbens (NAcc). RESULTS Rats microinjected with the HCN-2 coding vector into the VTA showed (i) a ~2-fold increase in their voluntary EtOH intake compared to control animals, (ii) lentiviral-HCN-2-treated animals also showed an increased CPP to EtOH (~3-fold), (iii) a significant higher locomotor activity (~2-fold), and (iv) increased dopamine release in NAcc upon systemic administration of EtOH (~2-fold). CONCLUSIONS Overexpression of HCN-2 ionic channel in the VTA of rats results in an increase in voluntary EtOH intake, EtOH-induced CPP, locomotor activity, and dopamine release in NAcc, suggesting that HCN levels in the VTA are relevant for the rewarding properties of EtOH.
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Affiliation(s)
- Mario Rivera-Meza
- Program of Molecular and Clinical Pharmacology, Institute of Biomedical Sciences, Faculty of Medicine, University of Chile, Santiago, Chile
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Stillitano F, Lonardo G, Giunti G, Del Lungo M, Coppini R, Spinelli V, Sartiani L, Poggesi C, Mugelli A, Cerbai E. Chronic atrial fibrillation alters the functional properties of If in the human atrium. J Cardiovasc Electrophysiol 2013; 24:1391-400. [PMID: 23869794 DOI: 10.1111/jce.12212] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Revised: 05/24/2013] [Accepted: 05/29/2013] [Indexed: 01/08/2023]
Abstract
INTRODUCTION Despite the evidence that the hyperpolarization-activated current (If) is highly modulated in human cardiomyopathies, no definite data exist in chronic atrial fibrillation (cAF). We investigated the expression, function, and modulation of If in human cAF. METHODS AND RESULTS Right atrial samples were obtained from sinus rhythm (SR, n = 49) or cAF (duration >1 year, n = 31) patients undergoing corrective cardiac surgery. Among f-channel isoforms expressed in the human atrium (HCN1, 2 and 4), HCN4 mRNA levels measured by RT-PCR were significantly reduced. However, protein expression was preserved in cAF compared to SR (+85% for HCN4); concurrently, miR-1 expression was significantly reduced. In patch-clamped atrial myocytes, current-specific conductance (gf) was significantly increased in cAF at voltages around the threshold for If activation (-60 to -80 mV); accordingly, a 10-mV rightward shift of the activation curve occurred (P < 0.01). β-Adrenergic and 5-HT4 receptor stimulation exerted similar effects on If in cAF and SR cells, while the ANP-mediated effect was significantly reduced (P < 0.02), suggesting downregulation of natriuretic peptide signaling. CONCLUSIONS In human cAF modifications in transcriptional and posttranscriptional mechanisms of HCN channels occur, associated with a slight yet significant gain-of-function of If , which may contribute to enhanced atrial ectopy.
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Affiliation(s)
- Francesca Stillitano
- Center for Molecular Medicine (C.I.M.M.B.A.), Department NEUROFARBA, University of Firenze, Florence, Italy
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Papaioannou VE, Verkerk AO, Amin AS, de Bakker JMT. Intracardiac origin of heart rate variability, pacemaker funny current and their possible association with critical illness. Curr Cardiol Rev 2013; 9:82-96. [PMID: 22920474 PMCID: PMC3584310 DOI: 10.2174/157340313805076359] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2012] [Revised: 07/21/2012] [Accepted: 07/29/2012] [Indexed: 01/23/2023] Open
Abstract
Heart rate variability (HRV) is an indirect estimator of autonomic modulation of heart rate and is considered a risk marker in critical illness, particularly in heart failure and severe sepsis. A reduced HRV has been found in critically ill patients and has been associated with neuro-autonomic uncoupling or decreased baroreflex sensitivity. However, results from human and animal experimental studies indicate that intracardiac mechanisms might also be responsible for interbeat fluctuations. These studies have demonstrated that different membrane channel proteins and especially the so-called 'funny' current (If), an hyperpolarization-activated, inward current that drives diastolic depolarization resulting in spontaneous activity in cardiac pacemaker cells, are altered during critical illness. Furthermore, membrane channels kinetics seem to have significant impact upon HRV, whose early decrease might reflect a cellular metabolic stress. In this review article we present research findings regarding intracardiac origin of HRV, at the cellular level and in both isolated sinoatrial node and whole ex vivo heart preparations. In addition, we will review results from various experimental studies that support the interrelation between If and HRV during endotoxemia. We suggest that reduced HRV during sepsis could also be associated with altered pacemaker cell membrane properties, due to ionic current remodeling.
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Affiliation(s)
- Vasilios E Papaioannou
- Democritus University of Thrace, Alexandroupolis University Hospital, Intensive Care Unit, Alexandroupolis Medical School, Dragana 68100, Greece.
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Paz JT, Davidson TJ, Frechette ES, Delord B, Parada I, Peng K, Deisseroth K, Huguenard JR. Closed-loop optogenetic control of thalamus as a tool for interrupting seizures after cortical injury. Nat Neurosci 2012. [PMID: 23143518 DOI: 10.1038/nn.3269).] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cerebrocortical injuries such as stroke are a major source of disability. Maladaptive consequences can result from post-injury local reorganization of cortical circuits. For example, epilepsy is a common sequela of cortical stroke, but the mechanisms responsible for seizures following cortical injuries remain unknown. In addition to local reorganization, long-range, extra-cortical connections might be critical for seizure maintenance. In rats, we found that the thalamus, a structure that is remote from, but connected to, the injured cortex, was required to maintain cortical seizures. Thalamocortical neurons connected to the injured epileptic cortex underwent changes in HCN channel expression and became hyperexcitable. Targeting these neurons with a closed-loop optogenetic strategy revealed that reducing their activity in real-time was sufficient to immediately interrupt electrographic and behavioral seizures. This approach is of therapeutic interest for intractable epilepsy, as it spares cortical function between seizures, in contrast with existing treatments, such as surgical lesioning or drugs.
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Affiliation(s)
- Jeanne T Paz
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
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Paz JT, Davidson TJ, Frechette ES, Delord B, Parada I, Peng K, Deisseroth K, Huguenard JR. Closed-loop optogenetic control of thalamus as a tool for interrupting seizures after cortical injury. Nat Neurosci 2012; 16:64-70. [PMID: 23143518 PMCID: PMC3700812 DOI: 10.1038/nn.3269] [Citation(s) in RCA: 389] [Impact Index Per Article: 32.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 10/23/2012] [Indexed: 12/14/2022]
Abstract
Cerebrocortical injuries, such as stroke, are a major source of disability. Maladaptive consequences can result from post-injury local reorganization of cortical circuits. For example, epilepsy is a common sequela of cortical stroke, yet mechanisms responsible for seizures following cortical injuries remain unknown. In addition to local reorganization, long-range, extra-cortical connections might be critical for seizure maintenance. Here we report in rats the first evidence that the thalamus – a structure remote from but connected to the injured cortex – is required to maintain cortical seizures. Thalamocortical neurons connected to the injured epileptic cortex undergo changes in HCN channel expression and become hyperexcitable. Targeting these neurons with a closed-loop optogenetic strategy demonstrates that reducing their activity in real-time is sufficient to immediately interrupt electrographic and behavioral seizures. This approach is of therapeutic interest for intractable epilepsy, since it spares cortical function between seizures, in contrast to existing treatments such as surgical lesioning or drugs.
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Affiliation(s)
- Jeanne T Paz
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
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Salem KA, Adrian TE, Qureshi MA, Parekh K, Oz M, Howarth FC. Shortening and intracellular Ca2+ in ventricular myocytes and expression of genes encoding cardiac muscle proteins in early onset type 2 diabetic Goto-Kakizaki rats. Exp Physiol 2012; 97:1281-91. [PMID: 22581745 DOI: 10.1113/expphysiol.2012.066639] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
There has been a spectacular rise in the global prevalence of type 2 diabetes mellitus. Cardiovascular complications are the major cause of morbidity and mortality in diabetic patients. Contractile dysfunction, associated with disturbances in excitation-contraction coupling, has been widely demonstrated in the diabetic heart. The aim of this study was to investigate the pattern of cardiac muscle genes that are involved in the process of excitation-contraction coupling in the hearts of early onset (8-10 weeks of age) type 2 diabetic Goto-Kakizaki (GK) rats. Gene expression was assessed in ventricular muscle with real-time RT-PCR; shortening and intracellular Ca(2+) were measured in ventricular myocytes with video edge detection and fluorescence photometry, respectively. The general characteristics of the GK rats included elevated fasting and non-fasting blood glucose and blood glucose at 120 min following a glucose challenge. Expression of genes encoding cardiac muscle proteins (Myh6/7, Mybpc3, Myl1/3, Actc1, Tnni3, Tnn2, Tpm1/2/4 and Dbi) and intercellular proteins (Gja1/4/5/7, Dsp and Cav1/3) were unaltered in GK ventricle compared with control ventricle. The expression of genes encoding some membrane pumps and exchange proteins was unaltered (Atp1a1/2, Atp1b1 and Slc8a1), whilst others were either upregulated (Atp1a3, relative expression 2.61 ± 0.69 versus 0.84 ± 0.23) or downregulated (Slc9a1, 0.62 ± 0.07 versus 1.08 ± 0.08) in GK ventricle compared with control ventricle. The expression of genes encoding some calcium (Cacna1c/1g, Cacna2d1/2d2 and Cacnb1/b2), sodium (Scn5a) and potassium channels (Kcna3/5, Kcnj3/5/8/11/12, Kchip2, Kcnab1, Kcnb1, Kcnd1/2/3, Kcne1/4, Kcnq1, Kcng2, Kcnh2, Kcnk3 and Kcnn2) were unaltered, whilst others were either upregulated (Cacna1h, 0.95 ± 0.16 versus 0.47 ± 0.09; Scn1b, 1.84 ± 0.16 versus 1.11 ± 0.11; and Hcn2, 1.55 ± 0.15 versus 1.03 ± 0.08) or downregulated (Hcn4, 0.16 ± 0.03 versus 0.37 ± 0.08; Kcna2, 0.35 ± 0.03 versus 0.80 ± 0.11; Kcna4, 0.79 ± 0.25 versus 1.90 ± 0.26; and Kcnj2, 0.52 ± 0.07 versus 0.78 ± 0.08) in GK ventricle compared with control ventricle. The amplitude of ventricular myocyte shortening and the intracellular Ca(2+) transient were unaltered; however, the time-to-peak shortening was prolonged and time-to-half decay of the Ca(2+) transient was shortened in GK myocytes compared with control myocytes. The results of this study demonstrate changes in expression of genes encoding various excitation-contraction coupling proteins that are associated with disturbances in myocyte shortening and intracellular Ca(2+) transport.
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Affiliation(s)
- K A Salem
- Department of Physiology, Faculty of Medicine & Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates
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Klöckner U, Rueckschloss U, Grossmann C, Ebelt H, Müller-Werdan U, Loppnow H, Werdan K, Gekle M. Differential reduction of HCN channel activity by various types of lipopolysaccharide. J Mol Cell Cardiol 2011; 51:226-35. [PMID: 21609720 DOI: 10.1016/j.yjmcc.2011.05.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 05/05/2011] [Accepted: 05/06/2011] [Indexed: 01/31/2023]
Abstract
Recently it was shown that lipopolysaccharide (LPS) impairs the pacemaker current in human atrial myocytes. It was speculated that reduced heart rate variability (HRV), typical of patients with severe sepsis, may partially be explained by this impairment. We evaluated the effect of various types of LPS on the activity of human hyperpolarization-activated cyclic nucleotide-gated channel 2 (hHCN2) expressed in HEK293 cells, and on pacemaker channels in native murine sino-atrial node (SAN) cells, in order to determine the structure of LPS necessary to modulate pacemaker channel function. Application of LPS caused a robust inhibition of hHCN2-mediated current (I(hHCN2)) owing to a negative shift of the voltage dependence of current activation and to a reduced maximal conductance. In addition, kinetics of channel gating were modulated by LPS. Pro-inflammatory LPS-types lacking the O-chain did not reduce I(hHCN2), whereas pro-inflammatory LPS-types containing the O-chain reduced I(hHCN2). On the other hand, a detoxified LPS without inflammatory activity, but containing the O-chain reduced I(hHCN2). Similar observations were made in HEK293 cells expressing hHCN4 and in murine SAN cells. This mechanistic analysis showed the novel finding that the O-chain of LPS is required for reduction of HCN channel activity. In the clinical situation the observed modulation of HCN channels may slow down diastolic depolarization of pacemaker cells and, hence, influence heart rate variability and heart rate.
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Affiliation(s)
- Udo Klöckner
- Julius-Bernstein-Institut für Physiologie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany.
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HCN-related channelopathies. Pflugers Arch 2010; 460:405-15. [DOI: 10.1007/s00424-010-0810-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 02/17/2010] [Accepted: 02/18/2010] [Indexed: 01/01/2023]
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Hegle AP, Nazzari H, Roth A, Angoli D, Accili EA. Evolutionary emergence of N-glycosylation as a variable promoter of HCN channel surface expression. Am J Physiol Cell Physiol 2010; 298:C1066-76. [PMID: 20130205 DOI: 10.1152/ajpcell.00389.2009] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
All four mammalian hyperpolarization-activated cyclic nucleotide-modulated (HCN) channel isoforms have been shown to undergo N-linked glycosylation in the brain. With the mouse HCN2 isoform as a prototype, HCN channels have further been suggested to require N-glycosylation for function, a provocative finding that would make them unique in the voltage-gated potassium channel superfamily. Here, we show that both the HCN1 and HCN2 isoforms are also predominantly N-glycosylated in the embryonic heart, where they are found in significant amounts and where HCN-mediated currents are known to regulate beating frequency. Surprisingly, we find that N-glycosylation is not required for HCN2 function, although its cell surface expression is highly dependent on the presence of N-glycans. Comparatively, disruption of N-glycosylation only modestly impacts cell surface expression of HCN1 and leaves permeation and gating functions almost unchanged. This difference between HCN1 and HCN2 is consistent with evolutionary trajectories that diverged in an isoform-specific manner after gene duplication from a common HCN ancestor that lacked N-glycosylation and was able to localize efficiently to the cell surface.
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Affiliation(s)
- Andrew P Hegle
- Department of Cellular and Physiological Sciences, University of British Columbia, Vancouver, Canada
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