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Kunzmann P, Krumbach JH, Saponaro A, Moroni A, Thiel G, Hamacher K. Anisotropic Network Analysis of Open/Closed HCN4 Channel Advocates Asymmetric Subunit Cooperativity in cAMP Modulation of Gating. J Chem Inf Model 2024; 64:4727-4738. [PMID: 38830626 PMCID: PMC11203669 DOI: 10.1021/acs.jcim.4c00360] [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: 03/01/2024] [Revised: 05/07/2024] [Accepted: 05/10/2024] [Indexed: 06/05/2024]
Abstract
Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels are opened in an allosteric manner by membrane hyperpolarization and cyclic nucleotides such as cAMP. Because of conflicting reports from experimental studies on whether cAMP binding to the four available binding sites in the channel tetramer operates cooperatively in gating, we employ here a computational approach as a promising route to examine ligand-induced conformational changes after binding to individual sites. By combining an elastic network model (ENM) with linear response theory (LRT) for modeling the apo-holo transition of the cyclic nucleotide-binding domain (CNBD) in HCN channels, we observe a distinct pattern of cooperativity matching the "positive-negative-positive" cooperativity reported from functional studies. This cooperativity pattern is highly conserved among HCN subtypes (HCN4, HCN1), but only to a lesser extent visible in structurally related channels, which are only gated by voltage (KAT1) or cyclic nucleotides (TAX4). This suggests an inherent cooperativity between subunits in HCN channels as part of a ligand-triggered gating mechanism in these channels.
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Affiliation(s)
- Patrick Kunzmann
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Jan H. Krumbach
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Andrea Saponaro
- Department
of Pharmacology and Biomolecular Sciences, University of Milano, via Balzaretti 9, 20133 Milano, Italy
| | - Anna Moroni
- Department
of Biosciences, Ion Channel Biophysics, University of Milan, via Celoria 26, 20133 Milan, Italy
| | - Gerhard Thiel
- Department
of Biology, Membrane Biophysics, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
- Centre
for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
| | - Kay Hamacher
- Department
of Biology, Computational Biology & Simulation, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
- Centre
for Synthetic Biology, TU Darmstadt, Schnittspahnstrasse 10, 64287 Darmstadt, Germany
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2
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Peters CH, Singh RK, Langley AA, Nichols WG, Ferris HR, Jeffrey DA, Proenza C, Bankston JR. LRMP inhibits cAMP potentiation of HCN4 channels by disrupting intramolecular signal transduction. eLife 2024; 12:RP92411. [PMID: 38652113 PMCID: PMC11037915 DOI: 10.7554/elife.92411] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024] Open
Abstract
Lymphoid restricted membrane protein (LRMP) is a specific regulator of the hyperpolarization-activated cyclic nucleotide-sensitive isoform 4 (HCN4) channel. LRMP prevents cAMP-dependent potentiation of HCN4, but the interaction domains, mechanisms of action, and basis for isoform-specificity remain unknown. Here, we identify the domains of LRMP essential for this regulation, show that LRMP acts by disrupting the intramolecular signal transduction between cyclic nucleotide binding and gating, and demonstrate that multiple unique regions in HCN4 are required for LRMP isoform-specificity. Using patch clamp electrophysiology and Förster resonance energy transfer (FRET), we identified the initial 227 residues of LRMP and the N-terminus of HCN4 as necessary for LRMP to associate with HCN4. We found that the HCN4 N-terminus and HCN4-specific residues in the C-linker are necessary for regulation of HCN4 by LRMP. Finally, we demonstrated that LRMP-regulation can be conferred to HCN2 by addition of the HCN4 N-terminus along with mutation of five residues in the S5 region and C-linker to the cognate HCN4 residues. Taken together, these results suggest that LRMP inhibits HCN4 through an isoform-specific interaction involving the N-terminals of both proteins that prevents the transduction of cAMP binding into a change in channel gating, most likely via an HCN4-specific orientation of the N-terminus, C-linker, and S4-S5 linker.
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Affiliation(s)
- Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Rohit K Singh
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
- Skaggs School of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Avery A Langley
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - William G Nichols
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Hannah R Ferris
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Danielle A Jeffrey
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
- Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical CampusAuroraUnited States
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3
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Porro A, Saponaro A, Castelli R, Introini B, Hafez Alkotob A, Ranjbari G, Enke U, Kusch J, Benndorf K, Santoro B, DiFrancesco D, Thiel G, Moroni A. A high affinity switch for cAMP in the HCN pacemaker channels. Nat Commun 2024; 15:843. [PMID: 38287019 PMCID: PMC10825183 DOI: 10.1038/s41467-024-45136-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Accepted: 01/16/2024] [Indexed: 01/31/2024] Open
Abstract
Binding of cAMP to Hyperpolarization activated cyclic nucleotide gated (HCN) channels facilitates pore opening. It is unclear why the isolated cyclic nucleotide binding domain (CNBD) displays in vitro lower affinity for cAMP than the full-length channel in patch experiments. Here we show that HCN are endowed with an affinity switch for cAMP. Alpha helices D and E, downstream of the cyclic nucleotide binding domain (CNBD), bind to and stabilize the holo CNBD in a high affinity state. These helices increase by 30-fold cAMP efficacy and affinity measured in patch clamp and ITC, respectively. We further show that helices D and E regulate affinity by interacting with helix C of the CNBD, similarly to the regulatory protein TRIP8b. Our results uncover an intramolecular mechanism whereby changes in binding affinity, rather than changes in cAMP concentration, can modulate HCN channels, adding another layer to the complex regulation of their activity.
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Affiliation(s)
| | - Andrea Saponaro
- Department of Pharmacological and Biomolecular Sciences, University of Milan, Milano, Italy
| | | | - Bianca Introini
- Department of Biosciences, University of Milan, Milano, Italy
| | | | - Golnaz Ranjbari
- Department of Biosciences, University of Milan, Milano, Italy
| | - Uta Enke
- Institut für Physiologie II, Universitätsklinikum Jena, Jena, Germany
| | - Jana Kusch
- Institut für Physiologie II, Universitätsklinikum Jena, Jena, Germany
| | - Klaus Benndorf
- Institut für Physiologie II, Universitätsklinikum Jena, Jena, Germany
| | - Bina Santoro
- Department of Neuroscience, Zuckerman Institute, Columbia University, New York, NY, USA
| | | | - Gerhard Thiel
- Department of Biology, TU-Darmstadt, Darmstadt, Germany
| | - Anna Moroni
- Department of Biosciences, University of Milan, Milano, Italy.
- Institute of Biophysics Milan, Consiglio Nazionale delle Ricerche, Milano, Italy.
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4
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Peters CH, Singh RK, Langley AA, Nichols WG, Ferris HR, Jeffrey DA, Proenza C, Bankston JR. LRMP inhibits cAMP potentiation of HCN4 channels by disrupting intramolecular signal transduction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.08.29.555242. [PMID: 37693562 PMCID: PMC10491135 DOI: 10.1101/2023.08.29.555242] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Lymphoid restricted membrane protein (LRMP) is a specific regulator of the hyperpolarization-activated cyclic nucleotide-sensitive isoform 4 (HCN4) channel. LRMP prevents cAMP-dependent potentiation of HCN4 but the interaction domains, mechanisms of action, and basis for isoform-specificity remain unknown. Here we identify the domains of LRMP essential for regulation. We show that LRMP acts by disrupting the intramolecular signal transduction between cyclic nucleotide binding and gating. And we demonstrate that multiple unique regions in HCN4 are required for LRMP isoform-specificity. Using patch clamp electrophysiology and Förster resonance energy transfer (FRET), we showed that the initial 227 residues of LRMP and the N-terminus of HCN4 are necessary for LRMP to interact with HCN4. We found that the HCN4 N-terminus and HCN4-specific residues in the C-linker are necessary for regulation of HCN4 by LRMP. And we demonstrate that LRMP-regulation can be conferred to HCN2 by addition of the HCN4 N-terminus along with mutation of 5 residues in the S5 region and C-linker to the cognate HCN4 residues. Taken together, these results suggest that LRMP inhibits HCN4 through an isoform-specific interaction involving the N-terminals of both proteins that prevents the transduction of cAMP binding into a change in channel gating via an HCN4-specific orientation of the N-terminus, C-linker, and S4-S5 linker.
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Affiliation(s)
- Colin H Peters
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
| | - Rohit K Singh
- Skaggs School of Pharmacy, Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, 12850 E. Montview Boulevard, Aurora, CO 80045
| | - Avery A Langley
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
| | - William G Nichols
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
| | - Hannah R Ferris
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
| | - Danielle A Jeffrey
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
- Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical Campus, 12631 E. 17 Avenue, Aurora, CO 80045
| | - John R Bankston
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, 12800 E. 19 Avenue, Aurora, CO 80045
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5
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Characterising ion channel structure and dynamics using fluorescence spectroscopy techniques. Biochem Soc Trans 2022; 50:1427-1445. [DOI: 10.1042/bst20220605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 09/21/2022] [Accepted: 10/04/2022] [Indexed: 11/17/2022]
Abstract
Ion channels undergo major conformational changes that lead to channel opening and ion conductance. Deciphering these structure-function relationships is paramount to understanding channel physiology and pathophysiology. Cryo-electron microscopy, crystallography and computer modelling provide atomic-scale snapshots of channel conformations in non-cellular environments but lack dynamic information that can be linked to functional results. Biophysical techniques such as electrophysiology, on the other hand, provide functional data with no structural information of the processes involved. Fluorescence spectroscopy techniques help bridge this gap in simultaneously obtaining structure-function correlates. These include voltage-clamp fluorometry, Förster resonance energy transfer, ligand binding assays, single molecule fluorescence and their variations. These techniques can be employed to unearth several features of ion channel behaviour. For instance, they provide real time information on local and global rearrangements that are inherent to channel properties. They also lend insights in trafficking, expression, and assembly of ion channels on the membrane surface. These methods have the advantage that they can be carried out in either native or heterologous systems. In this review, we briefly explain the principles of fluorescence and how these have been translated to study ion channel function. We also report several recent advances in fluorescence spectroscopy that has helped address and improve our understanding of the biophysical behaviours of different ion channel families.
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6
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Saponaro A, Vallese F, Porro A, Clarke OB. Validation of the binding stoichiometry between HCN channels and their neuronal regulator TRIP8b by single molecule measurements. Front Physiol 2022; 13:998176. [PMID: 36225302 PMCID: PMC9549148 DOI: 10.3389/fphys.2022.998176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
Tetratricopeptide repeat-containing Rab8b-interacting (TRIP8b) protein is a brain-specific subunit of Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels, a class of voltage-gated channels modulated by cyclic nucleotides. While the interaction between TRIP8b and the cytosolic C terminus of the channel has been structurally described, the HCN:TRIP8b stoichiometry is less characterized. We employed single molecule mass photometry (MP) to image HCN4 particles purified in complex with TRIP8b. Our data show that four TRIP8b subunits are bound to the tetrameric HCN4 particle, confirming a 1:1 stoichiometry.
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Affiliation(s)
- Andrea Saponaro
- Department of Biosciences, University of Milan, Milano, Italy
| | - Francesca Vallese
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, United States
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, United States
- Irving Institute for Clinical and Translational Research, Columbia University, New York, NY, United States
| | | | - Oliver B. Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, United States
- Department of Anesthesiology, Columbia University Irving Medical Center, New York, NY, United States
- Irving Institute for Clinical and Translational Research, Columbia University, New York, NY, United States
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7
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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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8
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Lyman KA, Han Y, Zhou C, Renteria I, Besing GL, Kurz JE, Chetkovich DM. Hippocampal cAMP regulates HCN channel function on two time scales with differential effects on animal behavior. Sci Transl Med 2021; 13:eabl4580. [PMID: 34818058 DOI: 10.1126/scitranslmed.abl4580] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Kyle A Lyman
- Department of Neurology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Ave., Chicago, IL 60611, USA.,Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA.,Department of Neurology, Stanford University, 453 Quarry Road, Palo Alto, CA 94304, USA
| | - Ye Han
- Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
| | - Chengwen Zhou
- Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
| | - Isabelle Renteria
- Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
| | - Gai-Linn Besing
- Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
| | - Jonathan E Kurz
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, 225 E. Chicago Ave., Chicago, IL 60611, USA
| | - Dane M Chetkovich
- Department of Neurology, Vanderbilt University Medical Center, 1161 21st Avenue South, Nashville, TN 37232, USA
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9
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Saponaro A, Bauer D, Giese MH, Swuec P, Porro A, Gasparri F, Sharifzadeh AS, Chaves-Sanjuan A, Alberio L, Parisi G, Cerutti G, Clarke OB, Hamacher K, Colecraft HM, Mancia F, Hendrickson WA, Siegelbaum SA, DiFrancesco D, Bolognesi M, Thiel G, Santoro B, Moroni A. Gating movements and ion permeation in HCN4 pacemaker channels. Mol Cell 2021; 81:2929-2943.e6. [PMID: 34166608 PMCID: PMC8294335 DOI: 10.1016/j.molcel.2021.05.033] [Citation(s) in RCA: 37] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 04/12/2021] [Accepted: 05/27/2021] [Indexed: 10/31/2022]
Abstract
The HCN1-4 channel family is responsible for the hyperpolarization-activated cation current If/Ih that controls automaticity in cardiac and neuronal pacemaker cells. We present cryoelectron microscopy (cryo-EM) structures of HCN4 in the presence or absence of bound cAMP, displaying the pore domain in closed and open conformations. Analysis of cAMP-bound and -unbound structures sheds light on how ligand-induced transitions in the channel cytosolic portion mediate the effect of cAMP on channel gating and highlights the regulatory role of a Mg2+ coordination site formed between the C-linker and the S4-S5 linker. Comparison of open/closed pore states shows that the cytosolic gate opens through concerted movements of the S5 and S6 transmembrane helices. Furthermore, in combination with molecular dynamics analyses, the open pore structures provide insights into the mechanisms of K+/Na+ permeation. Our results contribute mechanistic understanding on HCN channel gating, cyclic nucleotide-dependent modulation, and ion permeation.
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Affiliation(s)
- Andrea Saponaro
- Department of Biosciences, University of Milan, Milan, Italy
| | - Daniel Bauer
- Department of Biology, TU-Darmstadt, Darmstadt, Germany
| | - M Hunter Giese
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Paolo Swuec
- Department of Biosciences, University of Milan, Milan, Italy; Pediatric Research Center "Romeo ed Enrica Invernizzi," University of Milan, Milan, Italy
| | | | | | | | - Antonio Chaves-Sanjuan
- Department of Biosciences, University of Milan, Milan, Italy; Pediatric Research Center "Romeo ed Enrica Invernizzi," University of Milan, Milan, Italy
| | - Laura Alberio
- Department of Biosciences, University of Milan, Milan, Italy; Biosciences Institute, Newcastle University, Newcastle upon Tyne, UK
| | - Giacomo Parisi
- Center for Life Nano Science, Istituto Italiano di Tecnologia, Rome, Italy
| | - Gabriele Cerutti
- Department of Biochemical Sciences, Sapienza University of Rome, Rome, Italy
| | - Oliver B Clarke
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA; Department of Anesthesiology, Columbia University, New York, NY, USA
| | - Kay Hamacher
- Department of Biology, TU-Darmstadt, Darmstadt, Germany
| | - Henry M Colecraft
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA
| | - Wayne A Hendrickson
- Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA; Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA
| | - Steven A Siegelbaum
- Department of Neuroscience, Zuckerman Institute, Columbia University, New York, NY, USA
| | - Dario DiFrancesco
- Department of Biosciences, University of Milan, Milan, Italy; Institute of Biophysics-Milano, Consiglio Nazionale delle Ricerche, Rome, Italy
| | - Martino Bolognesi
- Department of Biosciences, University of Milan, Milan, Italy; Pediatric Research Center "Romeo ed Enrica Invernizzi," University of Milan, Milan, Italy
| | - Gerhard Thiel
- Department of Biology, TU-Darmstadt, Darmstadt, Germany
| | - Bina Santoro
- Department of Neuroscience, Zuckerman Institute, Columbia University, New York, NY, USA.
| | - Anna Moroni
- Department of Biosciences, University of Milan, Milan, Italy; Institute of Biophysics-Milano, Consiglio Nazionale delle Ricerche, Rome, Italy.
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10
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Combe CL, Gasparini S. I h from synapses to networks: HCN channel functions and modulation in neurons. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 166:119-132. [PMID: 34181891 DOI: 10.1016/j.pbiomolbio.2021.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 05/25/2021] [Accepted: 06/03/2021] [Indexed: 01/16/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide gated (HCN) channels and the current they carry, Ih, are widely and diversely distributed in the central nervous system (CNS). The distribution of the four subunits of HCN channels is variable within the CNS, within brain regions, and often within subcellular compartments. The precise function of Ih can depend heavily on what other channels are co-expressed. In this review, we give an overview of HCN channel structure, distribution, and modulation by cyclic adenosine monophosphate (cAMP). We then discuss HCN channel and Ih functions, where we have parsed the roles into two main effects: a steady effect on maintaining the resting membrane potential at relatively depolarized values, and slow channel dynamics. Within this framework, we discuss Ih involvement in resonance, synaptic integration, transmitter release, plasticity, and point out a special case, where the effects of Ih on the membrane potential and its slow channel dynamics have dual roles in thalamic neurons.
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Affiliation(s)
- Crescent L Combe
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA
| | - Sonia Gasparini
- Neuroscience Center of Excellence, Louisiana State University Health Sciences Center, New Orleans, LA, 70112, USA.
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11
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Characterization of the HCN Interaction Partner TRIP8b/PEX5R in the Intracardiac Nervous System of TRIP8b-Deficient and Wild-Type Mice. Int J Mol Sci 2021; 22:ijms22094772. [PMID: 33946275 PMCID: PMC8125662 DOI: 10.3390/ijms22094772] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/21/2021] [Accepted: 04/28/2021] [Indexed: 12/25/2022] Open
Abstract
The tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b/PEX5R) is an interaction partner and auxiliary subunit of hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are key for rhythm generation in the brain and in the heart. Since TRIP8b is expressed in central neurons but not in cardiomyocytes, the TRIP8b-HCN interaction has been studied intensely in the brain, but is deemed irrelevant in the cardiac conduction system. Still, to date, TRIP8b has not been studied in the intrinsic cardiac nervous system (ICNS), a neuronal network located within epicardial fat pads. In vitro electrophysiological studies revealed that TRIP8b-deficient mouse hearts exhibit increased atrial refractory and atrioventricular nodal refractory periods, compared to hearts of wild-type littermates. Meanwhile, heart rate, sino-nodal recovery time, and ventricular refractory period did not differ between genotypes. Trip8b mRNA was detected in the ICNS by quantitative polymerase chain reaction. RNAscope in situ hybridization confirmed Trip8b localization in neuronal somata and nerve fibers. Additionally, we found a very low amount of mRNAs in the sinus node and atrioventricular node, most likely attributable to the delicate fibers innervating the conduction system. In contrast, TRIP8b protein was not detectable. Our data suggest that TRIP8b in the ICNS may play a role in the modulation of atrial electrophysiology beyond HCN-mediated sino-nodal control of the heart.
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12
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Wort JL, Arya S, Ackermann K, Stewart AJ, Bode BE. Pulse Dipolar EPR Reveals Double-Histidine Motif Cu II-NTA Spin-Labeling Robustness against Competitor Ions. J Phys Chem Lett 2021. [PMID: 33715381 DOI: 10.17630/d7138874-55dd-4874-a2e8-c026fbc0b67f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pulse-dipolar EPR is an appealing strategy for structural characterization of complex systems in solution that complements other biophysical techniques. Significantly, the emergence of genetically encoded self-assembling spin labels exploiting exogenously introduced double-histidine motifs in conjunction with CuII-chelates offers high precision distance determination in systems nonpermissive to thiol-directed spin labeling. However, the noncovalency of this interaction exposes potential vulnerabilities to competition from adventitious divalent metal ions, and pH sensitivity. Herein, a combination of room-temperature isothermal titration calorimetry (ITC) and cryogenic relaxation-induced dipolar modulation enhancement (RIDME) measurements are applied to the model protein Streptococcus sp. group G. protein G, B1 domain (GB1). Results demonstrate double-histidine motif spin labeling using CuII-nitrilotriacetic acid (CuII-NTA) is robust against the competitor ligand ZnII-NTA at >1000-fold molar excess, and high nM binding affinity is surprisingly retained under acidic and basic conditions even though room temperature affinity shows a stronger pH dependence. This indicates the strategy is well-suited for diverse biological applications, with the requirement of other metal ion cofactors or slightly acidic pH not necessarily being prohibitive.
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Affiliation(s)
| | - Swati Arya
- School of Medicine, University of St. Andrews, North Haugh, St. Andrews, KY16 9TF, U.K
| | | | - Alan J Stewart
- School of Medicine, University of St. Andrews, North Haugh, St. Andrews, KY16 9TF, U.K
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13
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Wort J, Arya S, Ackermann K, Stewart AJ, Bode BE. Pulse Dipolar EPR Reveals Double-Histidine Motif Cu II-NTA Spin-Labeling Robustness against Competitor Ions. J Phys Chem Lett 2021; 12:2815-2819. [PMID: 33715381 PMCID: PMC8006131 DOI: 10.1021/acs.jpclett.1c00211] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
Pulse-dipolar EPR is an appealing strategy for structural characterization of complex systems in solution that complements other biophysical techniques. Significantly, the emergence of genetically encoded self-assembling spin labels exploiting exogenously introduced double-histidine motifs in conjunction with CuII-chelates offers high precision distance determination in systems nonpermissive to thiol-directed spin labeling. However, the noncovalency of this interaction exposes potential vulnerabilities to competition from adventitious divalent metal ions, and pH sensitivity. Herein, a combination of room-temperature isothermal titration calorimetry (ITC) and cryogenic relaxation-induced dipolar modulation enhancement (RIDME) measurements are applied to the model protein Streptococcus sp. group G. protein G, B1 domain (GB1). Results demonstrate double-histidine motif spin labeling using CuII-nitrilotriacetic acid (CuII-NTA) is robust against the competitor ligand ZnII-NTA at >1000-fold molar excess, and high nM binding affinity is surprisingly retained under acidic and basic conditions even though room temperature affinity shows a stronger pH dependence. This indicates the strategy is well-suited for diverse biological applications, with the requirement of other metal ion cofactors or slightly acidic pH not necessarily being prohibitive.
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Affiliation(s)
- Joshua
L. Wort
- EaStCHEM
School of Chemistry, Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St.
Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
| | - Swati Arya
- EaStCHEM
School of Chemistry, Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St.
Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
- School
of Medicine, University of St. Andrews, North Haugh, St. Andrews, KY16 9TF, U.K.
| | - Katrin Ackermann
- EaStCHEM
School of Chemistry, Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St.
Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
| | - Alan J. Stewart
- EaStCHEM
School of Chemistry, Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St.
Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
- School
of Medicine, University of St. Andrews, North Haugh, St. Andrews, KY16 9TF, U.K.
| | - Bela E. Bode
- EaStCHEM
School of Chemistry, Biomedical Sciences Research Complex, Centre
of Magnetic Resonance, University of St.
Andrews, North Haugh, St. Andrews, KY16 9ST, U.K.
- E-mail:
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14
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Bürgi J, Ekal L, Wilmanns M. Versatile allosteric properties in Pex5-like tetratricopeptide repeat proteins to induce diverse downstream function. Traffic 2021; 22:140-152. [PMID: 33580581 DOI: 10.1111/tra.12785] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 01/30/2021] [Accepted: 02/10/2021] [Indexed: 01/11/2023]
Abstract
Proteins composed of tetratricopeptide repeat (TPR) arrays belong to the α-solenoid tandem-repeat family that have unique properties in terms of their overall conformational flexibility and ability to bind to multiple protein ligands. The peroxisomal matrix protein import receptor Pex5 comprises two TPR triplets that recognize protein cargos with a specific C-terminal Peroxisomal Targeting Signal (PTS) 1 motif. Import of PTS1-containing protein cargos into peroxisomes through a transient pore is mainly driven by allosteric binding, coupling and release mechanisms, without a need for external energy. A very similar TPR architecture is found in the functionally unrelated TRIP8b, a regulator of the hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channel. TRIP8b binds to the HCN ion channel via a C-terminal sequence motif that is nearly identical to the PTS1 motif of Pex5 receptor cargos. Pex5, Pex5-related Pex9, and TRIP8b also share a less conserved N-terminal domain. This domain provides a second protein cargo-binding site and plays a distinct role in allosteric coupling of initial cargo loading by PTS1 motif-mediated interactions and different downstream functional readouts. The data reviewed here highlight the overarching role of molecular allostery in driving the diverse functions of TPR array proteins, which could form a model for other α-solenoid tandem-repeat proteins involved in translocation processes across membranes.
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Affiliation(s)
- Jérôme Bürgi
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Lakhan Ekal
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Hamburg, Germany.,University Hamburg Clinical Center Hamburg-Eppendorf, Hamburg, Germany
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15
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Han Y, Lyman KA, Foote KM, Chetkovich DM. The structure and function of TRIP8b, an auxiliary subunit of hyperpolarization-activated cyclic-nucleotide gated channels. Channels (Austin) 2020; 14:110-122. [PMID: 32189562 PMCID: PMC7153792 DOI: 10.1080/19336950.2020.1740501] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 02/18/2020] [Accepted: 02/21/2020] [Indexed: 02/08/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are expressed throughout the mammalian central nervous system (CNS). These channels have been implicated in a wide range of diseases, including Major Depressive Disorder and multiple subtypes of epilepsy. The diversity of functions that HCN channels perform is in part attributable to differences in their subcellular localization. To facilitate a broad range of subcellular distributions, HCN channels are bound by auxiliary subunits that regulate surface trafficking and channel function. One of the best studied auxiliary subunits is tetratricopeptide-repeat containing, Rab8b-interacting protein (TRIP8b). TRIP8b is an extensively alternatively spliced protein whose only known function is to regulate HCN channels. TRIP8b binds to HCN pore-forming subunits at multiple interaction sites that differentially regulate HCN channel function and subcellular distribution. In this review, we summarize what is currently known about the structure and function of TRIP8b isoforms with an emphasis on the role of this auxiliary subunit in health and disease.
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Affiliation(s)
- Ye Han
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Kyle A. Lyman
- Department of Neurology, Stanford University, Palo Alto, CA, USA
| | - Kendall M. Foote
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Dane M. Chetkovich
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
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16
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Shi Z, Bamford IJ, McKinley JW, Devi SPS, Vahedipour A, Bamford NS. Propranolol Relieves L-Dopa-Induced Dyskinesia in Parkinsonian Mice. Brain Sci 2020; 10:brainsci10120903. [PMID: 33255421 PMCID: PMC7760026 DOI: 10.3390/brainsci10120903] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/16/2020] [Accepted: 11/19/2020] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Parkinsonism is caused by dopamine (DA) insufficiency and results in a hypokinetic movement disorder. Treatment with L-Dopa can restore DA availability and improve motor function, but patients can develop L-Dopa-induced dyskinesia (LID), a secondary hyperkinetic movement disorder. The mechanism underlying LID remains unknown, and new treatments are needed. Experiments in mice have shown that DA deficiency promotes an imbalance between striatal acetylcholine (ACh) and DA that contributes to motor dysfunction. While treatment with L-Dopa improves DA availability, it promotes a paradoxical rise in striatal ACh and a further increase in the ACh to DA ratio may promote LID. METHODS We used conditional Slc6a3DTR/+ mice to model progressive DA deficiency and the β-adrenergic receptor (β-AR) antagonist propranolol to limit the activity of striatal cholinergic interneurons (ChIs). DA-deficient mice were treated with L-Dopa and the dopa decarboxylase inhibitor benserazide. LID and motor performance were assessed by rotarod, balance beam, and open field testing. Electrophysiological experiments characterized the effects of β-AR ligands on striatal ChIs. RESULTS LID was observed in a subset of DA-deficient mice. Treatment with propranolol relieved LID and motor hyperactivity. Electrophysiological experiments showed that β-ARs can effectively modulate ChI firing. CONCLUSIONS The work suggests that pharmacological modulation of ChIs by β-ARs might provide a therapeutic option for managing LID.
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Affiliation(s)
- Ziqing Shi
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
| | - Ian J. Bamford
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
| | - Jonathan W. McKinley
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
| | - Suma Priya Sudarsana Devi
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
| | - Annie Vahedipour
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
| | - Nigel S. Bamford
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; (Z.S.); (I.J.B.); (J.W.M.); (S.P.S.D.); (A.V.)
- Departments of Neurology and Cellular and Molecular Physiology, Yale University, New Haven, CT 06510, USA
- Department of Neurology, University of Washington, Seattle, WA 98105, USA
- Correspondence: ; Tel.: +1-203-785-5708
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17
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Porro A, Binda A, Pisoni M, Donadoni C, Rivolta I, Saponaro A. Rational design of a mutation to investigate the role of the brain protein TRIP8b in limiting the cAMP response of HCN channels in neurons. J Gen Physiol 2020; 152:e202012596. [PMID: 32633755 PMCID: PMC7478871 DOI: 10.1085/jgp.202012596] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 05/02/2020] [Accepted: 06/08/2020] [Indexed: 01/22/2023] Open
Abstract
TRIP8b (tetratricopeptide repeat-containing Rab8b-interacting protein) is the neuronal regulatory subunit of HCN channels, a family of voltage-dependent cation channels also modulated by direct cAMP binding. TRIP8b interacts with the C-terminal region of HCN channels and controls both channel trafficking and gating. The association of HCN channels with TRIP8b is required for the correct expression and subcellular targeting of the channel protein in vivo. TRIP8b controls HCN gating by interacting with the cyclic nucleotide-binding domain (CNBD) and competing for cAMP binding. Detailed structural knowledge of the complex between TRIP8b and CNBD was used as a starting point to engineer a mutant channel, whose gating is controlled by cAMP, but not by TRIP8b, while leaving TRIP8b-dependent regulation of channel trafficking unaltered. We found two-point mutations (N/A and C/D) in the loop connecting the CNBD to the C-linker (N-bundle loop) that, when combined, strongly reduce the binding of TRIP8b to CNBD, leaving cAMP affinity unaltered both in isolated CNBD and in the full-length protein. Proof-of-principle experiments performed in cultured cortical neurons confirm that the mutant channel provides a genetic tool for dissecting the two effects of TRIP8b (gating versus trafficking). This will allow the study of the functional role of the TRIP8b antagonism of cAMP binding, a thus far poorly investigated aspect of HCN physiology in neurons.
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Affiliation(s)
| | - Anna Binda
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | | | - Chiara Donadoni
- Department of Biosciences, University of Milano, Milano, Italy
| | - Ilaria Rivolta
- School of Medicine and Surgery, University of Milano-Bicocca, Monza, Italy
| | - Andrea Saponaro
- Department of Biosciences, University of Milano, Milano, Italy
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18
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Isoform-specific regulation of HCN4 channels by a family of endoplasmic reticulum proteins. Proc Natl Acad Sci U S A 2020; 117:18079-18090. [PMID: 32647060 DOI: 10.1073/pnas.2006238117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ion channels in excitable cells function in macromolecular complexes in which auxiliary proteins modulate the biophysical properties of the pore-forming subunits. Hyperpolarization-activated, cyclic nucleotide-sensitive HCN4 channels are critical determinants of membrane excitability in cells throughout the body, including thalamocortical neurons and cardiac pacemaker cells. We previously showed that the properties of HCN4 channels differ dramatically in different cell types, possibly due to the endogenous expression of auxiliary proteins. Here, we report the discovery of a family of endoplasmic reticulum (ER) transmembrane proteins that associate with and modulate HCN4. Lymphoid-restricted membrane protein (LRMP, Jaw1) and inositol trisphosphate receptor-associated guanylate kinase substrate (IRAG, Mrvi1, and Jaw1L) are homologous proteins with small ER luminal domains and large cytoplasmic domains. Despite their homology, LRMP and IRAG have distinct effects on HCN4. LRMP is a loss-of-function modulator that inhibits the canonical depolarizing shift in the voltage dependence of HCN4 in response to the binding of cAMP. In contrast, IRAG causes a gain of HCN4 function by depolarizing the basal voltage dependence in the absence of cAMP. The mechanisms of action of LRMP and IRAG are independent of trafficking and cAMP binding, and they are specific to the HCN4 isoform. We also found that IRAG is highly expressed in the mouse sinoatrial node where computer modeling predicts that its presence increases HCN4 current. Our results suggest important roles for LRMP and IRAG in the regulation of cellular excitability, as tools for advancing mechanistic understanding of HCN4 channel function, and as possible scaffolds for coordination of signaling pathways.
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19
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Porro A, Thiel G, Moroni A, Saponaro A. cyclic AMP Regulation and Its Command in the Pacemaker Channel HCN4. Front Physiol 2020; 11:771. [PMID: 32733276 PMCID: PMC7358946 DOI: 10.3389/fphys.2020.00771] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 06/11/2020] [Indexed: 11/13/2022] Open
Abstract
Direct regulation of the pacemaker “funny” current (If) by cyclic AMP (cAMP) underlies heart rate modulation by the autonomic nervous system. At the molecular level, cAMP activates hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that drive If in sinoatrial node (SAN) myocytes. Even though HCN channel genes were identified more than 20 years ago, the understanding of how cAMP regulates their gating is still fragmented. Here we summarize present understanding on how the cAMP signal is transmitted from the cytosolic to the transmembrane (TM) domain in HCN4. We further discuss how detailed structural knowledge prompted the development of pharmacological/genetic tools for the control of cAMP regulation in these channels.
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Affiliation(s)
| | - Gerhard Thiel
- Department of Biology, Technische Universität Darmstadt, Darmstadt, Germany
| | - Anna Moroni
- Department of Biosciences, University of Milan, Milan, Italy
| | - Andrea Saponaro
- Department of Biosciences, University of Milan, Milan, Italy
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20
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Foote KM, Lyman KA, Han Y, Michailidis IE, Heuermann RJ, Mandikian D, Trimmer JS, Swanson GT, Chetkovich DM. Phosphorylation of the HCN channel auxiliary subunit TRIP8b is altered in an animal model of temporal lobe epilepsy and modulates channel function. J Biol Chem 2019; 294:15743-15758. [PMID: 31492750 DOI: 10.1074/jbc.ra119.010027] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Revised: 08/30/2019] [Indexed: 12/14/2022] Open
Abstract
Temporal lobe epilepsy (TLE) is a prevalent neurological disorder with many patients experiencing poor seizure control with existing anti-epileptic drugs. Thus, novel insights into the mechanisms of epileptogenesis and identification of new drug targets can be transformative. Changes in ion channel function have been shown to play a role in generating the aberrant neuronal activity observed in TLE. Previous work demonstrates that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate neuronal excitability and are mislocalized within CA1 pyramidal cells in a rodent model of TLE. The subcellular distribution of HCN channels is regulated by an auxiliary subunit, tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b), and disruption of this interaction correlates with channel mislocalization. However, the molecular mechanisms responsible for HCN channel dysregulation in TLE are unclear. Here we investigated whether changes in TRIP8b phosphorylation are sufficient to alter HCN channel function. We identified a phosphorylation site at residue Ser237 of TRIP8b that enhances binding to HCN channels and influences channel gating by altering the affinity of TRIP8b for the HCN cytoplasmic domain. Using a phosphospecific antibody, we demonstrate that TRIP8b phosphorylated at Ser237 is enriched in CA1 distal dendrites and that phosphorylation is reduced in the kainic acid model of TLE. Overall, our findings indicate that the TRIP8b-HCN interaction can be modulated by changes in phosphorylation and suggest that loss of TRIP8b phosphorylation may affect HCN channel properties during epileptogenesis. These results highlight the potential of drugs targeting posttranslational modifications to restore TRIP8b phosphorylation to reduce excitability in TLE.
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Affiliation(s)
- Kendall M Foote
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, Illinois 60611.,Department of Pharmacology, Northwestern University, Chicago, Illinois 60611.,Vanderbilt University Medical Center Department of Neurology, Nashville, Tennessee 37232
| | - Kyle A Lyman
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, Illinois 60611.,Vanderbilt University Medical Center Department of Neurology, Nashville, Tennessee 37232.,Department of Medicine, Stanford University, Palo Alto, California 94305
| | - Ye Han
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, Illinois 60611.,Vanderbilt University Medical Center Department of Neurology, Nashville, Tennessee 37232
| | - Ioannis E Michailidis
- Vanderbilt University Medical Center Department of Neurology, Nashville, Tennessee 37232
| | - Robert J Heuermann
- Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110
| | - Danielle Mandikian
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616
| | - James S Trimmer
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California 95616.,Department of Physiology and Membrane Biology, University of California, Davis, California 95616
| | - Geoffrey T Swanson
- Department of Pharmacology, Northwestern University, Chicago, Illinois 60611.,Department of Neurobiology, Northwestern University, Evanston, Illinois 60208
| | - Dane M Chetkovich
- Vanderbilt University Medical Center Department of Neurology, Nashville, Tennessee 37232
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21
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McKinley JW, Shi Z, Kawikova I, Hur M, Bamford IJ, Sudarsana Devi SP, Vahedipour A, Darvas M, Bamford NS. Dopamine Deficiency Reduces Striatal Cholinergic Interneuron Function in Models of Parkinson's Disease. Neuron 2019; 103:1056-1072.e6. [PMID: 31324539 DOI: 10.1016/j.neuron.2019.06.013] [Citation(s) in RCA: 78] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2018] [Revised: 03/12/2019] [Accepted: 06/18/2019] [Indexed: 11/30/2022]
Abstract
Motor and cognitive functions depend on the coordinated interactions between dopamine (DA) and acetylcholine (ACh) at striatal synapses. Increased ACh availability was assumed to accompany DA deficiency based on the outcome of pharmacological treatments and measurements in animals that were critically depleted of DA. Using Slc6a3DTR/+ diphtheria-toxin-sensitive mice, we demonstrate that a progressive and L-dopa-responsive DA deficiency reduces ACh availability and the transcription of hyperpolarization-activated cation (HCN) channels that encode the spike timing of ACh-releasing tonically active striatal interneurons (ChIs). Although the production and release of ACh and DA are reduced, the preponderance of ACh over DA contributes to the motor deficit. The increase in striatal ACh relative to DA is heightened via D1-type DA receptors that activate ChIs in response to DA release from residual axons. These results suggest that stabilizing the expression of HCN channels may improve ACh-DA reciprocity and motor function in Parkinson's disease (PD). VIDEO ABSTRACT.
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Affiliation(s)
| | - Ziqing Shi
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA
| | - Ivana Kawikova
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA
| | - Matthew Hur
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA
| | - Ian J Bamford
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA
| | | | - Annie Vahedipour
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA
| | - Martin Darvas
- Department of Pathology, University of Washington, Seattle, WA 98105, USA
| | - Nigel S Bamford
- Department of Pediatrics, Yale University, New Haven, CT 06510, USA; Department of Neurology and Cellular and Molecular Physiology, Yale University, New Haven, CT 06510, USA; Department of Neurology, University of Washington, Seattle, WA 98105, USA.
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22
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Abstract
Using a short peptide to regulate the activity of HCN ion channels illustrates how physiological modulators could inspire new drugs.
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Affiliation(s)
- Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, United States.,Department of Medicine, Division of Cardiology, University of Colorado Anschutz Medical Campus, Aurora, United States
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23
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Saponaro A, Cantini F, Porro A, Bucchi A, DiFrancesco D, Maione V, Donadoni C, Introini B, Mesirca P, Mangoni ME, Thiel G, Banci L, Santoro B, Moroni A. A synthetic peptide that prevents cAMP regulation in mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels. eLife 2018; 7:35753. [PMID: 29923826 PMCID: PMC6023613 DOI: 10.7554/elife.35753] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/14/2018] [Indexed: 12/13/2022] Open
Abstract
Binding of TRIP8b to the cyclic nucleotide binding domain (CNBD) of mammalian hyperpolarization-activated cyclic nucleotide-gated (HCN) channels prevents their regulation by cAMP. Since TRIP8b is expressed exclusively in the brain, we envisage that it can be used for orthogonal control of HCN channels beyond the central nervous system. To this end, we have identified by rational design a 40-aa long peptide (TRIP8bnano) that recapitulates affinity and gating effects of TRIP8b in HCN isoforms (hHCN1, mHCN2, rbHCN4) and in the cardiac current If in rabbit and mouse sinoatrial node cardiomyocytes. Guided by an NMR-derived structural model that identifies the key molecular interactions between TRIP8bnano and the HCN CNBD, we further designed a cell-penetrating peptide (TAT-TRIP8bnano) which successfully prevented β-adrenergic activation of mouse If leaving the stimulation of the L-type calcium current (ICaL) unaffected. TRIP8bnano represents a novel approach to selectively control HCN activation, which yields the promise of a more targeted pharmacology compared to pore blockers.
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Affiliation(s)
- Andrea Saponaro
- Department of Biosciences, University of Milan, Milan, Italy
| | - Francesca Cantini
- Department of Chemistry, University of Florence, Florence, Italy.,Magnetic Resonance Center, University of Florence, Florence, Italy
| | | | - Annalisa Bucchi
- Department of Biosciences, University of Milan, Milan, Italy
| | | | - Vincenzo Maione
- Interuniversity Consortium for Magnetic Resonance of Metalloproteins, Sesto Fiorentino, Italy
| | - Chiara Donadoni
- Department of Biosciences, University of Milan, Milan, Italy
| | - Bianca Introini
- Department of Biosciences, University of Milan, Milan, Italy
| | - Pietro Mesirca
- Institut de Génomique Fonctionnelle, CNRS, INSERM F-34094, Université de Montpellier, Montpellier, France.,Laboratory of Excellence Ion Channels Science and Therapeutics, Valbonne, France
| | - Matteo E Mangoni
- Institut de Génomique Fonctionnelle, CNRS, INSERM F-34094, Université de Montpellier, Montpellier, France.,Laboratory of Excellence Ion Channels Science and Therapeutics, Valbonne, France
| | - Gerhard Thiel
- Department of Biology, TU-Darmstadt, Darmstadt, Germany
| | - Lucia Banci
- Department of Chemistry, University of Florence, Florence, Italy.,Magnetic Resonance Center, University of Florence, Florence, Italy.,Interuniversity Consortium for Magnetic Resonance of Metalloproteins, Sesto Fiorentino, Italy.,Institute of Neurosciences, Consiglio Nazionale delle Ricerche, Florence, Italy
| | - Bina Santoro
- Department of Neuroscience, Columbia University, New York, United States
| | - Anna Moroni
- Department of Biosciences, University of Milan, Milan, Italy.,Institute of Biophysics, Consiglio Nazionale delle Ricerche, Milan, Italy
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