1
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Peters CH, Singh RK, Bankston JR, Proenza C. Regulation of HCN Channels by Protein Interactions. Front Physiol 2022; 13:928507. [PMID: 35795651 PMCID: PMC9251338 DOI: 10.3389/fphys.2022.928507] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 06/01/2022] [Indexed: 11/30/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-sensitive (HCN) channels are key regulators of subthreshold membrane potentials in excitable cells. The four mammalian HCN channel isoforms, HCN1-HCN4, are expressed throughout the body, where they contribute to diverse physiological processes including cardiac pacemaking, sleep-wakefulness cycles, memory, and somatic sensation. While all HCN channel isoforms produce currents when expressed by themselves, an emerging list of interacting proteins shape HCN channel excitability to influence the physiologically relevant output. The best studied of these regulatory proteins is the auxiliary subunit, TRIP8b, which binds to multiple sites in the C-terminus of the HCN channels to regulate expression and disrupt cAMP binding to fine-tune neuronal HCN channel excitability. Less is known about the mechanisms of action of other HCN channel interaction partners like filamin A, Src tyrosine kinase, and MinK-related peptides, which have a range of effects on HCN channel gating and expression. More recently, the inositol trisphosphate receptor-associated cGMP-kinase substrates IRAG1 and LRMP (also known as IRAG2), were discovered as specific regulators of the HCN4 isoform. This review summarizes the known protein interaction partners of HCN channels and their mechanisms of action and identifies gaps in our knowledge.
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Affiliation(s)
- Colin H. Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Rohit K. Singh
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - John R. Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- Department of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
- *Correspondence: Catherine Proenza,
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2
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Jansen LAR, Forster LA, Smith XL, Rubaharan M, Murphy AZ, Baro DJ. Changes in peripheral HCN2 channels during persistent inflammation. Channels (Austin) 2021; 15:165-179. [PMID: 33423595 PMCID: PMC7808421 DOI: 10.1080/19336950.2020.1870086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 12/22/2020] [Accepted: 12/23/2020] [Indexed: 02/01/2023] Open
Abstract
Nociceptor sensitization following nerve injury or inflammation leads to chronic pain. An increase in the nociceptor hyperpolarization-activated current, Ih, is observed in many models of pathological pain. Pharmacological blockade of Ih prevents the mechanical and thermal hypersensitivity that occurs during pathological pain. Alterations in the Hyperpolarization-activated Cyclic Nucleotide-gated ion channel 2 (HCN2) mediate Ih-dependent thermal and mechanical hyperalgesia. Limited knowledge exists regarding the nature of these changes during chronic inflammatory pain. Modifications in HCN2 expression and post-translational SUMOylation have been observed in the Complete Freund's Adjuvant (CFA) model of chronic inflammatory pain. Intra-plantar injection of CFA into the rat hindpaw induces unilateral hyperalgesia that is sustained for up to 14 days following injection. The hindpaw is innervated by primary afferents in lumbar DRG, L4-6. Adjustments in HCN2 expression and SUMOylation have been well-documented for L5 DRG during the first 7 days of CFA-induced inflammation. Here, we examine bilateral L4 and L6 DRG at day 1 and day 3 post-CFA. Using L4 and L6 DRG cryosections, HCN2 expression and SUMOylation were measured with immunohistochemistry and proximity ligation assays, respectively. Our findings indicate that intra-plantar injection of CFA elicited a bilateral increase in HCN2 expression in L4 and L6 DRG at day 1, but not day 3, and enhanced HCN2 SUMOylation in ipsilateral L6 DRG at day 1 and day 3. Changes in HCN2 expression and SUMOylation were transient over this time course. Our study suggests that HCN2 is regulated by multiple mechanisms during CFA-induced inflammation.
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Affiliation(s)
- L-A. R. Jansen
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - L. A. Forster
- Department of Biology, Georgia State University, Atlanta, Georgia
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
| | - X. L. Smith
- Department of Biology, Georgia State University, Atlanta, Georgia
| | - M. Rubaharan
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
| | - A. Z. Murphy
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
| | - D. J. Baro
- Department of Biology, Georgia State University, Atlanta, Georgia
- Neuroscience Institute, Georgia State University, Atlanta, Georgia
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3
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Luo P, He G, Liu D. HCN channels: New targets for the design of an antidepressant with rapid effects. J Affect Disord 2019; 245:764-770. [PMID: 30448761 DOI: 10.1016/j.jad.2018.11.081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2018] [Revised: 10/22/2018] [Accepted: 11/11/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Major depressive disorder (MDD) is a prevalent neuropsychiatric disease that carries a staggering global burden. Although numerous antidepressants are available on the market, unfortunately, many patients die by committing suicide as a result of the therapeutic lag between treatment initiation and the improvement of depressive symptoms. This therapeutic lag highlights the need for new antidepressants that provide rapid relief of depressive symptoms. METHOD In this review, we discuss the seminal researches on hyperpolarization-activated cyclic nucleotide-gated (HCN) channels in animal models of depression and highlight the substantial evidence supporting the development of rapid-acting antidepressants targeting HCN channels. RESULTS HCN channels are associated with the risk of depression and targeting HCN channels or its auxiliary subunit tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) function may exert a rapid antidepressant-like effect. CONCLUSIONS Compounds acting on HCN subunits or the TRIP8b-HCN interaction site may be excellent candidates for development into effective drugs with rapid antidepressant action.
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Affiliation(s)
- Pan Luo
- Department of Pharmacy, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - GuoFang He
- Department of Pharmacy, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
| | - Dong Liu
- Department of Pharmacy, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
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4
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Ramírez J, Duijvenboden SV, Ntalla I, Mifsud B, Warren HR, Tzanis E, Orini M, Tinker A, Lambiase PD, Munroe PB. Thirty loci identified for heart rate response to exercise and recovery implicate autonomic nervous system. Nat Commun 2018; 9:1947. [PMID: 29769521 PMCID: PMC5955978 DOI: 10.1038/s41467-018-04148-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Accepted: 04/06/2018] [Indexed: 12/25/2022] Open
Abstract
Impaired capacity to increase heart rate (HR) during exercise (ΔHRex), and a reduced rate of recovery post-exercise (ΔHRrec) are associated with higher cardiovascular mortality rates. Currently, the genetic basis of both phenotypes remains to be elucidated. We conduct genome-wide association studies (GWASs) for ΔHRex and ΔHRrec in ~40,000 individuals, followed by replication in ~27,000 independent samples, all from UK Biobank. Six and seven single-nucleotide polymorphisms for ΔHRex and ΔHRrec, respectively, formally replicate. In a full data set GWAS, eight further loci for ΔHRex and nine for ΔHRrec are genome-wide significant (P ≤ 5 × 10−8). In total, 30 loci are discovered, 8 being common across traits. Processes of neural development and modulation of adrenergic activity by the autonomic nervous system are enriched in these results. Our findings reinforce current understanding of HR response to exercise and recovery and could guide future studies evaluating its contribution to cardiovascular risk prediction. Genome-wide association studies have identified multiple loci for resting heart rate (HR) but the genetic factors associated with HR increase during and HR recovery after exercise are less well studied. Here, the authors examine both traits in a two-stage GWAS design in up to 67,257 individuals from UK Biobank.
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Affiliation(s)
- Julia Ramírez
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,Institute of Cardiovascular Science, University College London, London, WC1E 6BT, UK
| | - Stefan van Duijvenboden
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,Institute of Cardiovascular Science, University College London, London, WC1E 6BT, UK
| | - Ioanna Ntalla
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Borbala Mifsud
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,NIHR Barts Cardiovascular Biomedical Research Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Helen R Warren
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,NIHR Barts Cardiovascular Biomedical Research Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Evan Tzanis
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,NIHR Barts Cardiovascular Biomedical Research Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Michele Orini
- Barts Heart Centre, St Bartholomews Hospital, London, EC1A 7BE, UK.,Mechanical Engineering Department, University College London, London, WC1E 6BT, UK
| | - Andrew Tinker
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.,NIHR Barts Cardiovascular Biomedical Research Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Pier D Lambiase
- Institute of Cardiovascular Science, University College London, London, WC1E 6BT, UK. .,Barts Heart Centre, St Bartholomews Hospital, London, EC1A 7BE, UK.
| | - Patricia B Munroe
- Clinical Pharmacology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK. .,NIHR Barts Cardiovascular Biomedical Research Centre, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.
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5
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Sartiani L, Mannaioni G, Masi A, Novella Romanelli M, Cerbai E. The Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: from Biophysics to Pharmacology of a Unique Family of Ion Channels. Pharmacol Rev 2017; 69:354-395. [PMID: 28878030 DOI: 10.1124/pr.117.014035] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Accepted: 07/07/2017] [Indexed: 12/22/2022] Open
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels are important members of the voltage-gated pore loop channels family. They show unique features: they open at hyperpolarizing potential, carry a mixed Na/K current, and are regulated by cyclic nucleotides. Four different isoforms have been cloned (HCN1-4) that can assemble to form homo- or heterotetramers, characterized by different biophysical properties. These proteins are widely distributed throughout the body and involved in different physiologic processes, the most important being the generation of spontaneous electrical activity in the heart and the regulation of synaptic transmission in the brain. Their role in heart rate, neuronal pacemaking, dendritic integration, learning and memory, and visual and pain perceptions has been extensively studied; these channels have been found also in some peripheral tissues, where their functions still need to be fully elucidated. Genetic defects and altered expression of HCN channels are linked to several pathologies, which makes these proteins attractive targets for translational research; at the moment only one drug (ivabradine), which specifically blocks the hyperpolarization-activated current, is clinically available. This review discusses current knowledge about HCN channels, starting from their biophysical properties, origin, and developmental features, to (patho)physiologic role in different tissues and pharmacological modulation, ending with their present and future relevance as drug targets.
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Affiliation(s)
- Laura Sartiani
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Guido Mannaioni
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Alessio Masi
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Maria Novella Romanelli
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
| | - Elisabetta Cerbai
- Department of Neurosciences, Psychology, Drug Research, and Child Health, University of Florence, Firenze, Italy
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6
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Motloch LJ, Larbig R, Darabi T, Reda S, Motloch KA, Wernly B, Lichtenauer M, Gebing T, Schwaiger A, Zagidullin N, Wolny M, Hoppe UC. Long-QT syndrome-associated caveolin-3 mutations differentially regulate the hyperpolarization-activated cyclic nucleotide gated channel 4. Physiol Int 2017. [DOI: 10.1556/2060.104.2017.2.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Background
Caveolin-3 (cav-3) mutations are linked to the long-QT syndrome (LQTS) causing distinct clinical symptoms. Hyperpolarization-activated cyclic nucleotide channel 4 (HCN4) underlies the pacemaker current If. It associates with cav-3 and both form a macromolecular complex.
Methods
To examine the effects of human LQTS-associated cav-3 mutations on HCN4-channel function, HEK293-cells were cotransfected with HCN4 and wild-type (WT) cav-3 or a LQTS-associated cav-3 mutant (T78M, A85T, S141R, or F97C). HCN4 currents were recorded using the whole-cell patch-clamp technique.
Results
WT cav-3 significantly decreased HCN4 current density and shifted midpoint of activation into negative direction. HCN4 current properties were differentially modulated by LQTS-associated cav-3 mutations. When compared with WT cav-3, A85T, F97C, and T78M did not alter the specific effect of cav-3, but S141R significantly increased HCN4 current density. Compared with WT cav-3, no significant modifications of voltage dependence of steady-state activation curves were observed. However, while WT cav-3 alone had no significant effect on HCN4 current activation, all LQTS-associated cav-3 mutations significantly accelerated HCN4 activation kinetics.
Conclusions
Our results indicate that HCN4 channel function is modulated by cav-3. LQTS-associated mutations of cav-3 differentially influence pacemaker current properties indicating a pathophysiological role in clinical manifestations.
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Affiliation(s)
- LJ Motloch
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - R Larbig
- 2Division of Electrophysiology, Department of Cardiovascular Medicine, University Hospital Muenster, Muenster, Germany
| | - T Darabi
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - S Reda
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - KA Motloch
- 3Research Program for Ophthalmology and Glaucoma Research, University Clinic of Ophthalmology and Optometry, Paracelsus Medical University/SALK, Salzburg, Austria
| | - B Wernly
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - M Lichtenauer
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - T Gebing
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - A Schwaiger
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - N Zagidullin
- 4Department of Internal Diseases, Bashkir State Medical University, Ufa, Russia
| | - M Wolny
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
| | - UC Hoppe
- 1Department of Internal Medicine II, Paracelsus Medical University, Salzburg, Austria
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7
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DiFrancesco JC, DiFrancesco D. Dysfunctional HCN ion channels in neurological diseases. Front Cell Neurosci 2015; 6:174. [PMID: 25805968 PMCID: PMC4354400 DOI: 10.3389/fncel.2015.00071] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/18/2015] [Indexed: 11/25/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed as four different isoforms (HCN1-4) in the heart and in the central and peripheral nervous systems. HCN channels are activated by membrane hyperpolarization at voltages close to resting membrane potentials and carry the hyperpolarization-activated current, dubbed If (funny current) in heart and Ih in neurons. HCN channels contribute in several ways to neuronal activity and are responsible for many important cellular functions, including cellular excitability, generation, and modulation of rhythmic activity, dendritic integration, transmission of synaptic potentials, and plasticity phenomena. Because of their role, defective HCN channels are natural candidates in the search for potential causes of neurological disorders in humans. Several data, including growing evidence that some forms of epilepsy are associated with HCN mutations, support the notion of an involvement of dysfunctional HCN channels in different experimental models of the disease. Additionally, some anti-epileptic drugs are known to modify the activity of the Ih current. HCN channels are widely expressed in the peripheral nervous system and recent evidence has highlighted the importance of the HCN2 isoform in the transmission of pain. HCN channels are also present in the midbrain system, where they finely regulate the activity of dopaminergic neurons, and a potential role of these channels in the pathogenesis of Parkinson’s disease has recently emerged. The function of HCN channels is regulated by specific accessory proteins, which control the correct expression and modulation of the neuronal Ih current. Alteration of these proteins can severely interfere with the physiological channel function, potentially predisposing to pathological conditions. In this review we address the present knowledge of the association between HCN dysfunctions and neurological diseases, including clinical, genetic, and physiopathological aspects.
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Affiliation(s)
- Jacopo C DiFrancesco
- Department of Neurophysiology, Foundation Neurological Institute C. Besta Milano, Italy ; Department of Neurology, San Gerardo Hospital and Laboratory of Neurobiology, Milan Center for Neuroscience, University of Milano-Bicocca Monza, Italy
| | - Dario DiFrancesco
- The PaceLab, Department of Biosciences, University of Milano Milano, Italy
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8
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Lyashchenko AK, Redd KJ, Goldstein PA, Tibbs GR. cAMP control of HCN2 channel Mg2+ block reveals loose coupling between the cyclic nucleotide-gating ring and the pore. PLoS One 2014; 9:e101236. [PMID: 24983358 PMCID: PMC4077740 DOI: 10.1371/journal.pone.0101236] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/04/2014] [Indexed: 12/24/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-regulated HCN channels underlie the Na+-K+ permeable IH pacemaker current. As with other voltage-gated members of the 6-transmembrane KV channel superfamily, opening of HCN channels involves dilation of a helical bundle formed by the intracellular ends of S6 albeit this is promoted by inward, not outward, displacement of S4. Direct agonist binding to a ring of cyclic nucleotide-binding sites, one of which lies immediately distal to each S6 helix, imparts cAMP sensitivity to HCN channel opening. At depolarized potentials, HCN channels are further modulated by intracellular Mg2+ which blocks the open channel pore and blunts the inhibitory effect of outward K+ flux. Here, we show that cAMP binding to the gating ring enhances not only channel opening but also the kinetics of Mg2+ block. A combination of experimental and simulation studies demonstrates that agonist acceleration of block is mediated via acceleration of the blocking reaction itself rather than as a secondary consequence of the cAMP enhancement of channel opening. These results suggest that the activation status of the gating ring and the open state of the pore are not coupled in an obligate manner (as required by the often invoked Monod-Wyman-Changeux allosteric model) but couple more loosely (as envisioned in a modular model of protein activation). Importantly, the emergence of second messenger sensitivity of open channel rectification suggests that loose coupling may have an unexpected consequence: it may endow these erstwhile “slow” channels with an ability to exert voltage and ligand-modulated control over cellular excitability on the fastest of physiologically relevant time scales.
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Affiliation(s)
- Alex K. Lyashchenko
- Department of Anesthesiology, Columbia University, New York, New York, United States of America
| | - Kacy J. Redd
- Department of Neuroscience, Columbia University, New York, New York, United States of America
| | - Peter A. Goldstein
- Department of Anesthesiology, Weill Cornell Medical College, New York, New York, United States of America
| | - Gareth R. Tibbs
- Department of Anesthesiology, Columbia University, New York, New York, United States of America
- Department of Anesthesiology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail:
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9
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Cheng Q, Zhou Y. Novel role of KT5720 on regulating hyperpolarization-activated cyclic nucleotide-gated channel activity and dorsal root ganglion neuron excitability. DNA Cell Biol 2013; 32:320-8. [PMID: 23713946 DOI: 10.1089/dna.2013.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed in dorsal root ganglion (DRG) neurons, which are involved in diverse mechanisms that regulate DRG functions. Protein kinase A (PKA) is an essential kinase that plays a key role in almost all types of cells; it regulates the ion channel activity, the intracellular Ca(2+) concentration, as well as modulates cellular signals transduction. Nevertheless, the effect of PKA inhibition on the HCN channel activity in DRG neuron remains to be elucidated. Here we investigated the impact of PKA inhibition on the HCN channel activity and DRG neurons excitability. Our patch-clamp experiments both under whole-cell and single-channel conditions demonstrated that PKA inhibition with KT5720, a cell membrane permeable PKA-specific inhibitor, significantly attenuated HCN channel currents. Current clamp recording on freshly isolated DRG neurons showed KT5720 reduced overshoot amplitude and enhanced the threshold of the action potential. Moreover, our live-cell Ca(2+) imaging experiments illustrated KT5720 markedly reduced the intracellular Ca(2+) level. Collectively, this is the first report that addresses KT5720 attenuates the HCN channel activity and intracellular Ca(2+), thus reducing DRG neurons excitability. Therefore, our data strongly suggest that PKA is a potential target for curing HCN and DRG neuron relevant diseases.
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Affiliation(s)
- Qiuping Cheng
- College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei Province, China
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10
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Cao-Ehlker X, Zong X, Hammelmann V, Gruner C, Fenske S, Michalakis S, Wahl-Schott C, Biel M. Up-regulation of hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) by specific interaction with K+ channel tetramerization domain-containing protein 3 (KCTD3). J Biol Chem 2013; 288:7580-7589. [PMID: 23382386 DOI: 10.1074/jbc.m112.434803] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Most ion channels consist of the principal ion-permeating core subunit(s) and accessory proteins that are assembled with the channel core. The biological functions of the latter proteins are diverse and include the regulation of the biophysical properties of the ion channel, its connection to signaling pathways and the control of its cell surface expression. There is recent evidence that native hyperpolarization-activated cyclic nucleotide-gated channel complexes (HCN1-4) also contain accessory subunits, among which TRIP8b (tetratricopeptide repeat-containing Rab8b-interacting protein) has been most extensively studied. Here, we identify KCTD3, a so far uncharacterized member of the potassium channel tetramerization-domain containing (KCTD) protein family as an HCN3-interacting protein. KCTD3 is widely expressed in brain and some non-neuronal tissues and colocalizes with HCN3 in specific regions of the brain including hypothalamus. Within the HCN channel family, KCTD3 specifically binds to HCN3 and leads to a profound up-regulation of cell surface expression and current density of this channel. HCN3 can also functionally interact with TRIP8b; however, we found no evidence for channel complexes containing both TRIP8b and KCTD3. The C terminus of HCN3 is crucially required for functional interaction with KCTD3. Replacement of the cytosolic C terminus of HCN2 by the corresponding domain of HCN3 renders HCN2 sensitive to regulation by KCTD3. The C-terminal-half of KCTD3 is sufficient for binding to HCN3. However, the complete protein including the N-terminal tetramerization domain is needed for HCN3 current up-regulation. Together, our experiments indicate that KCTD3 is an accessory subunit of native HCN3 complexes.
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Affiliation(s)
- Xiaochun Cao-Ehlker
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Xiangang Zong
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Verena Hammelmann
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Christian Gruner
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Stefanie Fenske
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Stylianos Michalakis
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Christian Wahl-Schott
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany
| | - Martin Biel
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Ludwig-Maximilians-Universität München, 81377 Munich, Germany.
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11
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Barbuti A, Scavone A, Mazzocchi N, Terragni B, Baruscotti M, Difrancesco D. A caveolin-binding domain in the HCN4 channels mediates functional interaction with caveolin proteins. J Mol Cell Cardiol 2012; 53:187-95. [PMID: 22659290 DOI: 10.1016/j.yjmcc.2012.05.013] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 04/18/2012] [Accepted: 05/10/2012] [Indexed: 12/17/2022]
Abstract
Pacemaker (HCN) channels have a key role in the generation and modulation of spontaneous activity of sinoatrial node myocytes. Previous work has shown that compartmentation of HCN4 pacemaker channels within caveolae regulates important functions, but the molecular mechanism responsible is still unknown. HCN channels have a conserved caveolin-binding domain (CBD) composed of three aromatic amino acids at the N-terminus; we sought to evaluate the role of this CBD in channel-protein interaction by mutational analysis. We generated two HCN4 mutants with a disrupted CBD (Y259S, F262V) and two with conservative mutations (Y259F, F262Y). In CHO cells expressing endogenous caveolin-1 (cav-1), alteration of the CBD shifted channels activation to more positive potentials, slowed deactivation and made Y259S and F262V mutants insensitive to cholesterol depletion-induced caveolar disorganization. CBD alteration also caused a significant decrease of current density, due to a weaker HCN4-cav-1 interaction and accumulation of cytoplasmic channels. These effects were absent in mutants with a preserved CBD. In caveolin-1-free fibroblasts, HCN4 trafficking was impaired and current density reduced with all constructs; the activation curve of F262V was not altered relative to wt, and that of Y259S displayed only half the shift than in CHO cells. The conserved CBD present in all HCN isoforms mediates their functional interaction with caveolins. The elucidation of the molecular details of HCN4-cav-1 interaction can provide novel information to understand the basis of cardiac phenotypes associated with some forms of caveolinopathies.
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Affiliation(s)
- Andrea Barbuti
- Department of Biomolecular Sciences and Biotechnology, The PaceLab, Università degli Studi di Milano, via Celoria 26, 20133 Milano, Italy.
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12
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Glycogen synthase kinase 3β transfers cytoprotective signaling through connexin 43 onto mitochondrial ATP-sensitive K+ channels. Proc Natl Acad Sci U S A 2012; 109:E242-51. [PMID: 22238425 DOI: 10.1073/pnas.1107479109] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Despite compelling evidence supporting key roles for glycogen synthase kinase 3β (GSK3β), mitochondrial adenosine triphosphate-sensitive K(+) (mitoK(ATP)) channels, and mitochondrial connexin 43 (Cx43) in cytoprotection, it is not clear how these signaling modules are linked mechanistically. By patch-clamping the inner membrane of murine cardiac mitochondria, we found that inhibition of GSK3β activated mitoK(ATP). PKC activation and protein phosphatase 2a inhibition increased the open probability of mitoK(ATP) channels through GSK3β, and this GSK3β signal was mediated via mitochondrial Cx43. Moreover, (i) PKC-induced phosphorylation of mitochondrial Cx43 was reduced in GSK3β-S9A mice; (ii) Cx43 and GSK3β proteins associated in mitochondria; and (iii) SB216763-mediated reduction of infarct size was abolished in Cx43 KO mice in vivo, consistent with the notion that GSK3β inhibition results in mitoK(ATP) opening via mitochondrial Cx43. We therefore directly targeted mitochondrial Cx43 by the Cx43 C-terminal binding peptide RRNYRRNY for cardioprotection, circumventing further upstream pathways. RRNYRRNY activated mitoK(ATP) channels via Cx43. We directly recorded mitochondrial Cx43 channels that were activated by RRNYRRNY and blocked by the Cx43 mimetic peptide (43)GAP27. RRNYRRNY rendered isolated cardiomyocytes in vitro and the heart in vivo resistant to ischemia/reperfusion injury, indicating that mitochondrial Cx43- and/or mitoK(ATP)-mediated reduction of infarct size was not undermined by RRNYRRNY-related opening of sarcolemmal Cx43 channels. Our results demonstrate that GSK3β transfers cytoprotective signaling through mitochondrial Cx43 onto mitoK(ATP) channels and that Cx43 functions as a channel in mitochondria, being an attractive target for drug treatment against cardiomyocyte injury.
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13
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Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels have a key role in the control of heart rate and neuronal excitability. Ivabradine is the first compound acting on HCN channels to be clinically approved for the treatment of angina pectoris. HCN channels may offer excellent opportunities for the development of novel anticonvulsant, anaesthetic and analgesic drugs. In support of this idea, some well-established drugs that act on the central nervous system - including lamotrigine, gabapentin and propofol - have been found to modulate HCN channel function. This Review gives an up-to-date summary of compounds acting on HCN channels, and discusses strategies to further explore the potential of these channels for therapeutic intervention.
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14
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Lewis AS, Estep CM, Chetkovich DM. The fast and slow ups and downs of HCN channel regulation. Channels (Austin) 2011; 4:215-31. [PMID: 20305382 DOI: 10.4161/chan.4.3.11630] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels (h channels) form the molecular basis for the hyperpolarization-activated current, I(h), and modulation of h channels contributes to changes in cellular properties critical for normal functions in the mammalian brain and heart. Numerous mechanisms underlie h channel modulation during both physiological and pathological conditions, leading to distinct changes in gating, kinetics, surface expression, channel conductance or subunit composition of h channels. Here we provide a focused review examining mechanisms of h channel regulation, with an emphasis on recent findings regarding interacting proteins such as TRIP8b. This review is intended to serve as a comprehensive resource for physiologists to provide potential molecular mechanisms underlying functionally important changes in I(h) in different biological models, as well as for molecular biologists to delineate the predicted h channel changes associated with complex regulatory mechanisms in both normal function and in disease states.
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Affiliation(s)
- Alan S Lewis
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
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15
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Ross KA. Evidence for somatic gene conversion and deletion in bipolar disorder, Crohn's disease, coronary artery disease, hypertension, rheumatoid arthritis, type-1 diabetes, and type-2 diabetes. BMC Med 2011; 9:12. [PMID: 21291537 PMCID: PMC3048570 DOI: 10.1186/1741-7015-9-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Accepted: 02/03/2011] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND During gene conversion, genetic information is transferred unidirectionally between highly homologous but non-allelic regions of DNA. While germ-line gene conversion has been implicated in the pathogenesis of some diseases, somatic gene conversion has remained technically difficult to investigate on a large scale. METHODS A novel analysis technique is proposed for detecting the signature of somatic gene conversion from SNP microarray data. The Wellcome Trust Case Control Consortium has gathered SNP microarray data for two control populations and cohorts for bipolar disorder (BD), cardiovascular disease (CAD), Crohn's disease (CD), hypertension (HT), rheumatoid arthritis (RA), type-1 diabetes (T1D) and type-2 diabetes (T2D). Using the new analysis technique, the seven disease cohorts are analyzed to identify cohort-specific SNPs at which conversion is predicted. The quality of the predictions is assessed by identifying known disease associations for genes in the homologous duplicons, and comparing the frequency of such associations with background rates. RESULTS Of 28 disease/locus pairs meeting stringent conditions, 22 show various degrees of disease association, compared with only 8 of 70 in a mock study designed to measure the background association rate (P < 10-9). Additional candidate genes are identified using less stringent filtering conditions. In some cases, somatic deletions appear likely. RA has a distinctive pattern of events relative to other diseases. Similarities in patterns are apparent between BD and HT. CONCLUSIONS The associations derived represent the first evidence that somatic gene conversion could be a significant causative factor in each of the seven diseases. The specific genes provide potential insights about disease mechanisms, and are strong candidates for further study.
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Affiliation(s)
- Kenneth Andrew Ross
- Department of Computer Science, Columbia University, New York, NY 10027, USA.
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16
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Rottlaender D, Boengler K, Wolny M, Michels G, Endres-Becker J, Motloch LJ, Schwaiger A, Buechert A, Schulz R, Heusch G, Hoppe UC. Connexin 43 acts as a cytoprotective mediator of signal transduction by stimulating mitochondrial KATP channels in mouse cardiomyocytes. J Clin Invest 2010; 120:1441-53. [PMID: 20364086 DOI: 10.1172/jci40927] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Potassium (K+) channels in the inner mitochondrial membrane influence cell function and survival. Increasing evidence indicates that multiple signaling pathways and pharmacological actions converge on mitochondrial ATP-sensitive K+ (mitoKATP) channels and PKC to confer cytoprotection against necrotic and apoptotic cell injury. However, the molecular structure of mitoKATP channels remains unresolved, and the mitochondrial phosphoprotein(s) that mediate cytoprotection by PKC remain to be determined. As mice deficient in the main sarcolemmal gap junction protein connexin 43 (Cx43) lack this cytoprotection, we set out to investigate a possible link among mitochondrial Cx43, mitoKATP channel function, and PKC activation. By patch-clamping the inner membrane of subsarcolemmal murine cardiac mitochondria, we found that genetic Cx43 deficiency, pharmacological connexin inhibition by carbenoxolone, and Cx43 blockade by the mimetic peptide 43GAP27 each substantially reduced diazoxide-mediated stimulation of mitoKATP channels. Suppression of mitochondrial Cx43 inhibited mitoKATP channel activation by PKC. MitoKATP channels of interfibrillar mitochondria, which do not contain any detectable Cx43, were insensitive to both PKC activation and diazoxide, further demonstrating the role of Cx43 in mitoKATP channel stimulation and the compartmentation of mitochondria in cell signaling. Our results define a role for mitochondrial Cx43 in protecting cardiac cells from death and provide a link between cytoprotective stimuli and mitoKATP channel opening, making Cx43 an attractive therapeutic target for protection against cell injury.
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Affiliation(s)
- Dennis Rottlaender
- Department of Internal Medicine III, University of Cologne, Cologne, Germany
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17
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Biel M, Wahl-Schott C, Michalakis S, Zong X. Hyperpolarization-activated cation channels: from genes to function. Physiol Rev 2009; 89:847-85. [PMID: 19584315 DOI: 10.1152/physrev.00029.2008] [Citation(s) in RCA: 726] [Impact Index Per Article: 48.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a small subfamily of proteins within the superfamily of pore-loop cation channels. In mammals, the HCN channel family comprises four members (HCN1-4) that are expressed in heart and nervous system. The current produced by HCN channels has been known as I(h) (or I(f) or I(q)). I(h) has also been designated as pacemaker current, because it plays a key role in controlling rhythmic activity of cardiac pacemaker cells and spontaneously firing neurons. Extensive studies over the last decade have provided convincing evidence that I(h) is also involved in a number of basic physiological processes that are not directly associated with rhythmicity. Examples for these non-pacemaking functions of I(h) are the determination of the resting membrane potential, dendritic integration, synaptic transmission, and learning. In this review we summarize recent insights into the structure, function, and cellular regulation of HCN channels. We also discuss in detail the different aspects of HCN channel physiology in the heart and nervous system. To this end, evidence on the role of individual HCN channel types arising from the analysis of HCN knockout mouse models is discussed. Finally, we provide an overview of the impact of HCN channels on the pathogenesis of several diseases and discuss recent attempts to establish HCN channels as drug targets.
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Affiliation(s)
- Martin Biel
- Center for Integrated Protein Science CIPS-M and Zentrum für Pharmaforschung, Department Pharmazie, Pharmakologie für Naturwissenschaften, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, Munich D-81377, Germany.
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18
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Brandt MC, Endres-Becker J, Zagidullin N, Motloch LJ, Er F, Rottlaender D, Michels G, Herzig S, Hoppe UC. Effects of KCNE2 on HCN isoforms: distinct modulation of membrane expression and single channel properties. Am J Physiol Heart Circ Physiol 2009; 297:H355-63. [DOI: 10.1152/ajpheart.00154.2009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Hyperpolarization-activated cation (HCN) channels give rise to an inward current with similar but not identical characteristics compared with the pacemaker current ( If), suggesting that HCN channel function is modulated by regulatory β-subunits in native tissue. KCNE2 has been proposed to serve as a β-subunit of HCN channels; however, available data remain contradictory. To further clarify this situation, we therefore analyzed the effect of KCNE2 on whole cell currents, single channel properties, and membrane protein expression of all cardiac HCN isoforms in the CHO cell system. On the whole cell level, current densities of all HCN isoforms were significantly increased by KCNE2 without altering voltage dependence or current reversal. While these results correlated well with the KCNE2-mediated 2.2-fold and 1.6-fold increases of membrane protein levels of HCN2 and HCN4, respectively, no effect of KCNE2 on HCN1 expression was obtained. All HCN subtypes displayed faster activation kinetics upon coexpression with KCNE2. Most importantly, for the first time, we demonstrated modulation of single channel function by KCNE2, thus supporting direct functional interaction with HCN subunits. In the presence of KCNE2, the single channel amplitudes and conductance of HCN1, HCN2, and HCN4 were significantly increased versus control recordings. Mean open time was significantly increased in cells coexpressing HCN2 + KCNE2, whereas it was unaffected in HCN1 + KCNE2 cotransfected cells and reduced in HCN4 + KCNE2 cotransfected cells compared with the respective HCN subunits alone. Thus, we demonstrate KCNE2-mediated distinct effects on HCN membrane expression and direct functional modulation of HCN isoforms, further supporting that KCNE2 surves as a regulatory β-subunit of HCN channels.
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19
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Michels G, Khan IF, Endres-Becker J, Rottlaender D, Herzig S, Ruhparwar A, Wahlers T, Hoppe UC. Regulation of the Human Cardiac Mitochondrial Ca
2+
Uptake by 2 Different Voltage-Gated Ca
2+
Channels. Circulation 2009; 119:2435-43. [DOI: 10.1161/circulationaha.108.835389] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Background—
Impairment of intracellular Ca
2+
homeostasis and mitochondrial function has been implicated in the development of cardiomyopathy. Mitochondrial Ca
2+
uptake is thought to be mediated by the Ca
2+
uniporter (MCU) and a thus far speculative non-MCU pathway. However, the identity and properties of these pathways are a matter of intense debate, and possible functional alterations in diseased states have remained elusive.
Methods and Results—
By patch clamping the inner membrane of mitochondria from nonfailing and failing human hearts, we have identified 2 previously unknown Ca
2+
-selective channels, referred to as mCa1 and mCa2. Both channels are voltage dependent but differ significantly in gating parameters. Compared with mCa2 channels, mCa1 channels exhibit a higher single-channel amplitude, shorter openings, a lower open probability, and 3 to 5 subconductance states. Similar to the MCU, mCa1 is inhibited by 200 nmol/L ruthenium 360, whereas mCa2 is insensitive to 200 nmol/L ruthenium 360 and reduced only by very high concentrations (10 μmol/L). Both mitochondrial Ca
2+
channels are unaffected by blockers of other possibly Ca
2+
-conducting mitochondrial pores but were activated by spermine (1 mmol/L). Notably, activity of mCa1 and mCa2 channels is decreased in failing compared with nonfailing heart conditions, making them less effective for Ca
2+
uptake and likely Ca
2+
-induced metabolism.
Conclusions—
Thus, we conclude that the human mitochondrial Ca
2+
uptake is mediated by these 2 distinct Ca
2+
channels, which are functionally impaired in heart failure. Current properties reveal that the mCa1 channel underlies the human MCU and that the mCa2 channel is responsible for the ruthenium red–insensitive/low-sensitivity non-MCU–type mitochondrial Ca
2+
uptake.
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Affiliation(s)
- Guido Michels
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Ismail F. Khan
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Jeannette Endres-Becker
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Dennis Rottlaender
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Stefan Herzig
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Arjang Ruhparwar
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Thorsten Wahlers
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
| | - Uta C. Hoppe
- From the Department of Internal Medicine III (G.M., I.F.K., J.E.-B., D.R., U.C.H.), Center for Molecular Medicine (S.H., U.C.H.), Institute of Pharmacology (S.H.), and Department of Cardiothoracic Surgery (T.W.), University of Cologne, Cologne, and Department of Cardiac Surgery, University of Heidelberg, Heidelberg (A.R.), Germany
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20
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Gomes P, Saito T, Del Corsso C, Alioua A, Eghbali M, Toro L, Stefani E. Identification of a functional interaction between Kv4.3 channels and c-Src tyrosine kinase. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:1884-92. [PMID: 18620005 DOI: 10.1016/j.bbamcr.2008.06.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2008] [Revised: 06/02/2008] [Accepted: 06/02/2008] [Indexed: 12/31/2022]
Abstract
Voltage-gated K(+) (Kv) channels are key determinants of cardiac and neuronal excitability. A substantial body of evidence has accumulated in support of a role for Src family tyrosine kinases in the regulation of Kv channels. In this study, we examined the possibility that c-Src tyrosine kinase participates in the modulation of the transient voltage-dependent K(+) channel Kv4.3. Supporting a mechanistic link between Kv4.3 and c-Src, confocal microscopy analysis of HEK293 cells stably transfected with Kv4.3 showed high degree of co-localization of the two proteins at the plasma membrane. Our results further demonstrate an association between Kv4.3 and c-Src by co-immunoprecipitation and GST pull-down assays, this interaction being mediated by the SH2 and SH3 domains of c-Src. Furthermore, we show that Kv4.3 is tyrosine phosphorylated under basal conditions. The functional relevance of the observed interaction between Kv4.3 and c-Src was established in patch-clamp experiments, where application of the Src inhibitor PP2 caused a decrease in Kv4.3 peak current amplitude, but not the inactive structural analogue PP3. Conversely, intracellular application of recombinant c-Src kinase or the protein tyrosine phosphatase inhibitor bpV(phen) increased Kv4.3 peak current amplitude. In conclusion, our findings provide evidence that c-Src-induced Kv4.3 channel activation involves their association in a macromolecular complex and suggest a role for c-Src-Kv4.3 pathway in regulating cardiac and neuronal excitability.
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Affiliation(s)
- Pedro Gomes
- Department of Anesthesiology, Division of Molecular Medicine, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095-1778, USA.
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