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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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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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Wu Y, Luo XD, Xiang T, Li SJ, Ma MG, Chen ML. Activation of metabotropic glutamate receptor 1 regulates hippocampal CA1 region excitability in rats with status epilepticus by suppressing the HCN1 channel. Neural Regen Res 2023; 18:594-602. [DOI: 10.4103/1673-5374.350206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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A slit-diaphragm-associated protein network for dynamic control of renal filtration. Nat Commun 2022; 13:6446. [PMID: 36307401 PMCID: PMC9616960 DOI: 10.1038/s41467-022-33748-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Accepted: 09/29/2022] [Indexed: 12/25/2022] Open
Abstract
The filtration of blood in the kidney which is crucial for mammalian life is determined by the slit-diaphragm, a cell-cell junction between the foot processes of renal podocytes. The slit-diaphragm is thought to operate as final barrier or as molecular sensor of renal filtration. Using high-resolution proteomic analysis of slit-diaphragms affinity-isolated from rodent kidney, we show that the native slit-diaphragm is built from the junction-forming components Nephrin, Neph1 and Podocin and a co-assembled high-molecular weight network of proteins. The network constituents cover distinct classes of proteins including signaling-receptors, kinases/phosphatases, transporters and scaffolds. Knockout or knock-down of either the core components or the selected network constituents tyrosine kinase MER (MERTK), atrial natriuretic peptide-receptor C (ANPRC), integral membrane protein 2B (ITM2B), membrane-associated guanylate-kinase, WW and PDZ-domain-containing protein1 (MAGI1) and amyloid protein A4 resulted in target-specific impairment or disruption of the filtration process. Our results identify the slit-diaphragm as a multi-component system that is endowed with context-dependent dynamics via a co-assembled protein network.
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Xu F, Wang Y, Han L, Deng D, Ding Y, Ma L, Zhang Q, Chen X. PEX5R/Trip8b-HCN2 channel regulating neuroinflammation involved in perioperative neurocognitive disorders. Cell Biosci 2022; 12:156. [PMID: 36104739 PMCID: PMC9476339 DOI: 10.1186/s13578-022-00892-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 08/29/2022] [Indexed: 11/10/2022] Open
Abstract
Background Clinical and animal studies demonstrated that neuroinflammation from anesthesia (sevoflurane) is the main contributor to cause perioperative neurocognitive disorders (PND). Recently, it was reported that microglia respond to hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which was the target of sevoflurane. Whether HCN channels are involved in the induction of neuroinflammation after sevoflurane exposure is still unclear. Results Sevoflurane exposure had increased cognitive dysfunction and anxiety-like behaviors in rats. Rats inhaled with sevoflurane had activated microglia and increased neuroinflammation (IL-1β, IL-6, and TNF-α) in the hippocampus. RNA sequencing identified 132 DEGs (86 up-regulated and 46 down-regulated DEGs [differentially expressed genes]) in the hippocampus of PND rats. RNA-sequencing also uncovered that sevoflurane exposure down-regulates HCN2 expression. Pathway and process enrichment analysis suggests DEGs are mainly enriched in regulation of system process, positive regulation of glutamate secretion, secretion, regulation of synaptic transmission, regulation of nervous system process, behavior, negative regulation of sodium ion transport, and learning or memory. We validated that sevoflurane exposure can down-regulate the levels of PEX5R/Trip8b (an interaction partner and auxiliary subunit of HCN channels) and HCN1-4 channels in the hippocampus of PND rats. We used immunofluorescence staining to identify that HCN2 co-labels with neurons (Neun), astrocytes (GFAP), and microglia (iba1). We observed that the co-labeling of HCN2 with neurons or microglia decreased in the hippocampus and cortex after sevoflurane exposure. Blocking HCN2 by ZD7288 treatment further activated microglia and aggravated sevoflurane exposure-induced anxiety-like behavior, cognitive impairment, and neuroinflammation. Conclusions We concluded that sevoflurane exposure can induce an increased level of neuroinflammation, microglial activation, cognitive dysfunction, and anxiety-like behaviors in rats. HCN2 channel, as the target of sevoflurane action, mediates this process. HCN2 might be a target for the treatment and prevention of sevoflurane-induced PND. Supplementary Information The online version contains supplementary material available at 10.1186/s13578-022-00892-6.
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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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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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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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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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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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Santoro B, Shah MM. Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels as Drug Targets for Neurological Disorders. Annu Rev Pharmacol Toxicol 2020; 60:109-131. [PMID: 31914897 DOI: 10.1146/annurev-pharmtox-010919-023356] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are voltage-gated ion channels that critically modulate neuronal activity. Four HCN subunits (HCN1-4) have been cloned, each having a unique expression profile and distinctive effects on neuronal excitability within the brain. Consistent with this, the expression and function of these subunits are altered in diverse ways in neurological disorders. Here, we review current knowledge on the structure and distribution of the individual HCN channel isoforms, their effects on neuronal activity under physiological conditions, and how their expression and function are altered in neurological disorders, particularly epilepsy, neuropathic pain, and affective disorders. We discuss the suitability of HCN channels as therapeutic targets and how drugs might be strategically designed to specifically act on particular isoforms. We conclude that medicines that target individual HCN isoforms and/or their auxiliary subunit, TRIP8b, may provide valuable means of treating distinct neurological conditions.
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Affiliation(s)
- Bina Santoro
- Department of Neuroscience, Columbia University, New York, NY 10027, USA
| | - Mala M Shah
- Department of Pharmacology, School of Pharmacy, University College London, London WC1N 1AX, United Kingdom;
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Disease-associated HCN4 V759I variant is not sufficient to impair cardiac pacemaking. Pflugers Arch 2020; 472:1733-1742. [PMID: 33095298 PMCID: PMC7691308 DOI: 10.1007/s00424-020-02481-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 09/11/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022]
Abstract
The hyperpolarization-activated cation current If is a key determinant for cardiac pacemaker activity. It is conducted by subunits of the hyperpolarization-activated cyclic nucleotide–gated (HCN) channel family, of which HCN4 is predominant in mammalian heart. Both loss-of-function and gain-of-function mutations of the HCN4 gene are associated with sinus node dysfunction in humans; however, their functional impact is not fully understood yet. Here, we sought to characterize a HCN4 V759I variant detected in a patient with a family history of sick sinus syndrome. The genomic analysis yielded a mono-allelic HCN4 V759I variant in a 49-year-old woman presenting with a family history of sick sinus syndrome. This HCN4 variant was previously classified as putatively pathogenic because genetically linked to sudden infant death syndrome and malignant epilepsy. However, detailed electrophysiological and cell biological characterization of HCN4 V759I in Xenopus laevis oocytes and embryonic rat cardiomyocytes, respectively, did not reveal any obvious abnormality. Voltage dependence and kinetics of mutant channel activation, modulation of cAMP-gating by the neuronal HCN channel auxiliary subunit PEX5R, and cell surface expression were indistinguishable from wild-type HCN4. In good agreement, the clinically likewise affected mother of the patient does not exhibit the reported HCN4 variance. HCN4 V759I resembles an innocuous genetic HCN channel variant, which is not sufficient to disturb cardiac pacemaking. Once more, our work emphasizes the importance of careful functional interpretation of genetic findings not only in the context of hereditary cardiac arrhythmias.
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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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14
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Brandalise F, Kalmbach BE, Mehta P, Thornton O, Johnston D, Zemelman BV, Brager DH. Fragile X Mental Retardation Protein Bidirectionally Controls Dendritic I h in a Cell Type-Specific Manner between Mouse Hippocampus and Prefrontal Cortex. J Neurosci 2020; 40:5327-5340. [PMID: 32467357 PMCID: PMC7329306 DOI: 10.1523/jneurosci.1670-19.2020] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2019] [Revised: 04/06/2020] [Accepted: 04/15/2020] [Indexed: 11/21/2022] Open
Abstract
Channelopathies are implicated in Fragile X syndrome (FXS), yet the dysfunction of a particular ion channel varies with cell type. We previously showed that HCN channel function is elevated in CA1 dendrites of the fmr1-/y mouse model of FXS, but reduced in L5 PFC dendrites. Using male mice, we tested whether Fragile X Mental Retardation Protein (FMRPO), the protein whose absence causes FXS, differentially modulates HCN channels in CA1 versus L5 PFC dendrites. Using a combination of viral tools, intracellular peptide, and dendritic electrophysiology, we found that FMRP regulates HCN channels via a cell-autonomous protein-protein interaction. Virally expressed FMRP restored WT HCN channel-related dendritic properties in both CA1 and L5 neurons. Rapid intracellular perfusion of the non-mRNA binding N-terminal fragment, FMRP1-298, similarly restored dendritic function. In support of a protein-protein interaction, we found that FMRP associated with HCN-TRIP8b complexes in both hippocampus and PFC. Finally, voltage-clamp recordings showed that FMRP modulated Ih by regulating the number of functional dendritic HCN channels rather than individual channel properties. Together, these represent three novel findings as to the nature of the changes in dendritic function in CA1 and PFC neurons based on the presence or absence of FMRP. Moreover, our findings provide evidence that FMRP can regulate its targets in opposite directions depending upon the cellular milieu.SIGNIFICANCE STATEMENT Changes in dendritic function, and voltage-gated ion channels in particular, are increasingly the focus of neurological disorders. We, and others, previously identified cell type-specific channelopathies in a mouse of model of Fragile X syndrome. The present study shows that replacing Fragile X Mental Retardation Protein, which is absent in Fragile X syndrome, in adult CA1 and L5 PFC neurons regulates the number of functional dendritic HCN channels in a cell type-specific manner. These results suggest that Fragile X Mental Retardation Protein regulates dendritic HCN channels via a cell-autonomous protein--protein mechanism.
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Affiliation(s)
- Federico Brandalise
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Brian E Kalmbach
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Preeti Mehta
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Olivia Thornton
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Daniel Johnston
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Boris V Zemelman
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
| | - Darrin H Brager
- Center for Learning and Memory, University of Texas at Austin, Austin, Texas 78712
- Department of Neuroscience, University of Texas at Austin, Austin, Texas 78712
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15
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Kuo SH, Louis ED, Faust PL, Handforth A, Chang SY, Avlar B, Lang EJ, Pan MK, Miterko LN, Brown AM, Sillitoe RV, Anderson CJ, Pulst SM, Gallagher MJ, Lyman KA, Chetkovich DM, Clark LN, Tio M, Tan EK, Elble RJ. Current Opinions and Consensus for Studying Tremor in Animal Models. CEREBELLUM (LONDON, ENGLAND) 2019; 18:1036-1063. [PMID: 31124049 PMCID: PMC6872927 DOI: 10.1007/s12311-019-01037-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Tremor is the most common movement disorder; however, we are just beginning to understand the brain circuitry that generates tremor. Various neuroimaging, neuropathological, and physiological studies in human tremor disorders have been performed to further our knowledge of tremor. But, the causal relationship between these observations and tremor is usually difficult to establish and detailed mechanisms are not sufficiently studied. To overcome these obstacles, animal models can provide an important means to look into human tremor disorders. In this manuscript, we will discuss the use of different species of animals (mice, rats, fruit flies, pigs, and monkeys) to model human tremor disorders. Several ways to manipulate the brain circuitry and physiology in these animal models (pharmacology, genetics, and lesioning) will also be discussed. Finally, we will discuss how these animal models can help us to gain knowledge of the pathophysiology of human tremor disorders, which could serve as a platform towards developing novel therapies for tremor.
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Affiliation(s)
- Sheng-Han Kuo
- Department of Neurology, Columbia University, 650 West 168th Street, Room 305, New York, NY, 10032, USA.
| | - Elan D Louis
- Department of Neurology, Yale School of Medicine, Yale University, 800 Howard Avenue, Ste Lower Level, New Haven, CT, 06519, USA.
- Department of Chronic Disease Epidemiology, Yale School of Public Health, Yale University, New Haven, CT, USA.
- Center for Neuroepidemiology and Clinical Neurological Research, Yale School of Medicine, Yale University, New Haven, CT, USA.
| | - Phyllis L Faust
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
| | - Adrian Handforth
- Neurology Service, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, CA, USA
| | - Su-Youne Chang
- Department of Neurologic Surgery and Biomedical Engineering, Mayo Clinic, Rochester, MN, USA
| | - Billur Avlar
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Eric J Lang
- Department of Neuroscience and Physiology, New York University School of Medicine, New York, NY, USA
| | - Ming-Kai Pan
- Department of Medical Research and Neurology, National Taiwan University Hospital, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Lauren N Miterko
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
| | - Amanda M Brown
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Roy V Sillitoe
- Department of Pathology and Immunology, Baylor College of Medicine, Houston, TX, USA
- Program in Developmental Biology, Baylor College of Medicine, Houston, TX, USA
- Jan and Dan Duncan Neurological Research Institute of Texas Children's Hospital, Houston, TX, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
| | - Collin J Anderson
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | | | - Kyle A Lyman
- Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | | | - Lorraine N Clark
- Department of Pathology and Cell Biology, Columbia University Medical Center and the New York Presbyterian Hospital, New York, NY, USA
- Taub Institute for Research on Alzheimer's Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Murni Tio
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Eng-King Tan
- Department of Neurology, National Neuroscience Institute, Singapore, Singapore
- Duke-NUS Graduate Medical School, Singapore, Singapore
| | - Rodger J Elble
- Department of Neurology, Southern Illinois University School of Medicine, Springfield, IL, USA
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16
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Rathour RK, Narayanan R. Degeneracy in hippocampal physiology and plasticity. Hippocampus 2019; 29:980-1022. [PMID: 31301166 PMCID: PMC6771840 DOI: 10.1002/hipo.23139] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 05/27/2019] [Accepted: 06/25/2019] [Indexed: 12/17/2022]
Abstract
Degeneracy, defined as the ability of structurally disparate elements to perform analogous function, has largely been assessed from the perspective of maintaining robustness of physiology or plasticity. How does the framework of degeneracy assimilate into an encoding system where the ability to change is an essential ingredient for storing new incoming information? Could degeneracy maintain the balance between the apparently contradictory goals of the need to change for encoding and the need to resist change towards maintaining homeostasis? In this review, we explore these fundamental questions with the mammalian hippocampus as an example encoding system. We systematically catalog lines of evidence, spanning multiple scales of analysis that point to the expression of degeneracy in hippocampal physiology and plasticity. We assess the potential of degeneracy as a framework to achieve the conjoint goals of encoding and homeostasis without cross-interferences. We postulate that biological complexity, involving interactions among the numerous parameters spanning different scales of analysis, could establish disparate routes towards accomplishing these conjoint goals. These disparate routes then provide several degrees of freedom to the encoding-homeostasis system in accomplishing its tasks in an input- and state-dependent manner. Finally, the expression of degeneracy spanning multiple scales offers an ideal reconciliation to several outstanding controversies, through the recognition that the seemingly contradictory disparate observations are merely alternate routes that the system might recruit towards accomplishment of its goals.
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Affiliation(s)
- Rahul K. Rathour
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
| | - Rishikesh Narayanan
- Cellular Neurophysiology LaboratoryMolecular Biophysics Unit, Indian Institute of ScienceBangaloreIndia
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17
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Chang X, Wang J, Jiang H, Shi L, Xie J. Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels: An Emerging Role in Neurodegenerative Diseases. Front Mol Neurosci 2019; 12:141. [PMID: 31231190 PMCID: PMC6560157 DOI: 10.3389/fnmol.2019.00141] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 05/13/2019] [Indexed: 12/13/2022] Open
Abstract
Neurodegenerative diseases such as Parkinson's disease (PD), Alzheimer's disease (AD), amyotrophic lateral sclerosis (ALS), and spinal muscular atrophy (SMA) are chronic, progressive, and age-associated neurological disorders characterized by neuronal deterioration in specific brain regions. Although the specific pathological mechanisms underlying these disorders have remained elusive, ion channel dysfunction has become increasingly accepted as a potential mechanism for neurodegenerative diseases. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are encoded by the HCN1-4 gene family and conduct the hyperpolarization-activated current (I h). These channels play important roles in modulating cellular excitability, rhythmic activity, dendritic integration, and synaptic transmission. In the present review, we first provide a comprehensive picture of the role of HCN channels in PD by summarizing their role in the regulation of neuronal activity in PD-related brain regions. Dysfunction of I h may participate in 1-methyl-4-phenylpyridinium (MPP+)-induced toxicity and represent a pathogenic mechanism in PD. Given current reports of the critical role of HCN channels in neuroinflammation and depression, we also discussed the putative contribution of HCN channels in inflammatory processes and non-motor symptoms in PD. In the second section, we summarize how HCN channels regulate the formation of β-amyloid peptide in AD and the role of these channels in learning and memory. Finally, we briefly discuss the effects of HCN channels in ALS and SMA based on existing discoveries.
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Affiliation(s)
- Xiaoli Chang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Jun Wang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Hong Jiang
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Limin Shi
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
| | - Junxia Xie
- Department of Physiology, Shandong Provincial Key Laboratory of Pathogenesis and Prevention of Neurological Disorders and State Key Disciplines: Physiology, Medical College of Qingdao University, Qingdao, China
- Institute of Brain Science and Disease, Qingdao University, Qingdao, China
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18
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Hammelmann V, Stieglitz MS, Hülle H, Le Meur K, Kass J, Brümmer M, Gruner C, Rötzer RD, Fenske S, Hartmann J, Zott B, Lüthi A, Spahn S, Moser M, Isbrandt D, Ludwig A, Konnerth A, Wahl-Schott C, Biel M. Abolishing cAMP sensitivity in HCN2 pacemaker channels induces generalized seizures. JCI Insight 2019; 4:126418. [PMID: 31045576 DOI: 10.1172/jci.insight.126418] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 04/02/2019] [Indexed: 12/17/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are dually gated channels that are operated by voltage and by neurotransmitters via the cAMP system. cAMP-dependent HCN regulation has been proposed to play a key role in regulating circuit behavior in the thalamus. By analyzing a knockin mouse model (HCN2EA), in which binding of cAMP to HCN2 was abolished by 2 amino acid exchanges (R591E, T592A), we found that cAMP gating of HCN2 is essential for regulating the transition between the burst and tonic modes of firing in thalamic dorsal-lateral geniculate (dLGN) and ventrobasal (VB) nuclei. HCN2EA mice display impaired visual learning, generalized seizures of thalamic origin, and altered NREM sleep properties. VB-specific deletion of HCN2, but not of HCN4, also induced these generalized seizures of the absence type, corroborating a key role of HCN2 in this particular nucleus for controlling consciousness. Together, our data define distinct pathological phenotypes resulting from the loss of cAMP-mediated gating of a neuronal HCN channel.
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Affiliation(s)
- Verena Hammelmann
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Marc Sebastian Stieglitz
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Henrik Hülle
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Karim Le Meur
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jennifer Kass
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Manuela Brümmer
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Christian Gruner
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - René Dominik Rötzer
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Stefanie Fenske
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Jana Hartmann
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Benedikt Zott
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Anita Lüthi
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Saskia Spahn
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Markus Moser
- Department for Molecular Medicine, Max-Planck-Institut für Biochemie, Martinsried, Germany
| | - Dirk Isbrandt
- DZNE Research Group, Experimental Neurophysiology, Institute for Molecular and Behavioral Neuroscience, University of Cologne, Germany
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Arthur Konnerth
- Institute of Neuroscience, Technical University of Munich, Munich, Germany; and Munich Cluster for Systems Neurology (SyNergy) and Center for Integrated Protein Sciences (CIPSM), Munich, Germany
| | - Christian Wahl-Schott
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany.,Institut für Neurophysiologie, Medizinische Hochschule Hannover, Hannover, Germany
| | - Martin Biel
- Department of Pharmacy, Center for Drug Research, Center for Integrated Protein Science Munich, Ludwig-Maximilians-Universität München, Munich, Germany
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19
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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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20
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Günther A, Luczak V, Gruteser N, Abel T, Baumann A. HCN4 knockdown in dorsal hippocampus promotes anxiety-like behavior in mice. GENES BRAIN AND BEHAVIOR 2019; 18:e12550. [PMID: 30585408 PMCID: PMC6850037 DOI: 10.1111/gbb.12550] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 12/03/2018] [Accepted: 12/22/2018] [Indexed: 12/29/2022]
Abstract
Hyperpolarization‐activated and cyclic nucleotide‐gated (HCN) channels mediate the Ih current in the murine hippocampus. Disruption of the Ih current by knockout of HCN1, HCN2 or tetratricopeptide repeat‐containing Rab8b‐interacting protein has been shown to affect physiological processes such as synaptic integration and maintenance of resting membrane potentials as well as several behaviors in mice, including depressive‐like and anxiety‐like behaviors. However, the potential involvement of the HCN4 isoform in these processes is unknown. Here, we assessed the contribution of the HCN4 isoform to neuronal processing and hippocampus‐based behaviors in mice. We show that HCN4 is expressed in various regions of the hippocampus, with distinct expression patterns that partially overlapped with other HCN isoforms. For behavioral analysis, we specifically modulated HCN4 expression by injecting recombinant adeno‐associated viral (rAAV) vectors mediating expression of short hairpin RNA against hcn4 (shHcn4) into the dorsal hippocampus of mice. HCN4 knockdown produced no effect on contextual fear conditioning or spatial memory. However, a pronounced anxiogenic effect was evident in mice treated with shHcn4 compared to control littermates. Our findings suggest that HCN4 specifically contributes to anxiety‐like behaviors in mice.
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Affiliation(s)
- Anne Günther
- Laboratory for Synaptic Molecules of Memory Persistence, Center for Brain Science, RIKEN, Saitama, Japan.,Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Vincent Luczak
- Division of Biological Sciences and Center for Neural Circuits and Behavior, Neurobiology Section, Kavli Institute for Brain and Mind, University of California, San Diego, La Jolla, California, USA
| | - Nadine Gruteser
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
| | - Ted Abel
- Iowa Neuroscience Institute, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Arnd Baumann
- Institute of Complex Systems, Cellular Biophysics (ICS-4),Research Center Jülich, Jülich, Germany
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21
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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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22
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Silbernagel N, Walecki M, Schäfer MKH, Kessler M, Zobeiri M, Rinné S, Kiper AK, Komadowski MA, Vowinkel KS, Wemhöner K, Fortmüller L, Schewe M, Dolga AM, Scekic-Zahirovic J, Matschke LA, Culmsee C, Baukrowitz T, Monassier L, Ullrich ND, Dupuis L, Just S, Budde T, Fabritz L, Decher N. The VAMP-associated protein VAPB is required for cardiac and neuronal pacemaker channel function. FASEB J 2018; 32:6159-6173. [PMID: 29879376 PMCID: PMC6629115 DOI: 10.1096/fj.201800246r] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels encode neuronal and cardiac pacemaker currents. The composition of pacemaker channel complexes in different tissues is poorly understood, and the presence of additional HCN modulating subunits was speculated. Here we show that vesicle-associated membrane protein-associated protein B (VAPB), previously associated with a familial form of amyotrophic lateral sclerosis 8, is an essential HCN1 and HCN2 modulator. VAPB significantly increases HCN2 currents and surface expression and has a major influence on the dendritic neuronal distribution of HCN2. Severe cardiac bradycardias in VAPB-deficient zebrafish and VAPB-/- mice highlight that VAPB physiologically serves to increase cardiac pacemaker currents. An altered T-wave morphology observed in the ECGs of VAPB-/- mice supports the recently proposed role of HCN channels for ventricular repolarization. The critical function of VAPB in native pacemaker channel complexes will be relevant for our understanding of cardiac arrhythmias and epilepsies, and provides an unexpected link between these diseases and amyotrophic lateral sclerosis.-Silbernagel, N., Walecki, M., Schäfer, M.-K. H., Kessler, M., Zobeiri, M., Rinné, S., Kiper, A. K., Komadowski, M. A., Vowinkel, K. S., Wemhöner, K., Fortmüller, L., Schewe, M., Dolga, A. M., Scekic-Zahirovic, J., Matschke, L. A., Culmsee, C., Baukrowitz, T., Monassier, L., Ullrich, N. D., Dupuis, L., Just, S., Budde, T., Fabritz, L., Decher, N. The VAMP-associated protein VAPB is required for cardiac and neuronal pacemaker channel function.
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Affiliation(s)
- Nicole Silbernagel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Magdalena Walecki
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Martin K-H Schäfer
- Institute of Anatomy and Cell Biology, Philipps University, Marburg, Germany
| | - Mirjam Kessler
- Molecular Cardiology, Department of Internal Medicine II, University Hospital Ulm, Ulm, Germany
| | | | - Susanne Rinné
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Aytug K Kiper
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Marlene A Komadowski
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany.,Institute of Anatomy and Cell Biology, Philipps University, Marburg, Germany
| | - Kirsty S Vowinkel
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Konstantin Wemhöner
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Lisa Fortmüller
- Department of Cardiology II - Electrophysiology, University Hospital Münster, University of Münster, Munster, Germany
| | - Marcus Schewe
- Institute of Physiology, Christian-Albrechts University, Kiel, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, Phillips University, Marburg, Germany
| | - Jelena Scekic-Zahirovic
- Laboratoire de Pharmacologie et Toxicologie NeuroCardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Lina A Matschke
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, Phillips University, Marburg, Germany
| | - Thomas Baukrowitz
- Institute of Physiology, Christian-Albrechts University, Kiel, Germany
| | - Laurent Monassier
- Laboratoire de Pharmacologie et Toxicologie NeuroCardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Nina D Ullrich
- Institute of Physiology and Pathophysiology, University of Heidelberg, Heidelberg, Germany
| | - Luc Dupuis
- Laboratoire de Neurobiologie et Pharmacologie Cardiovasculaire, Faculté de Médecine, Université de Strasbourg, Strasbourg, France.,INSERM, Faculté de Médecine, Université de Strasbourg, Strasbourg, France
| | - Steffen Just
- Molecular Cardiology, Department of Internal Medicine II, University Hospital Ulm, Ulm, Germany
| | - Thomas Budde
- Institute for Physiology I, University of Münster, Munster, Germany
| | - Larissa Fabritz
- Department of Cardiology II - Electrophysiology, University Hospital Münster, University of Münster, Munster, Germany.,Institute of Cardiovascular Sciences, University Hospital Birmingham, University of Birmingham, Birmingham, United Kingdom.,Department of Cardiology, University Hospital Birmingham, University of Birmingham, Birmingham, United Kingdom.,Division of Rhythmology, Department of Genetic Epidemiology, University Hospital Münster, University of Münster, Munster, Germany.,Institute of Human Genetics, Department of Genetic Epidemiology, University Hospital Münster, University of Münster, Munster, Germany
| | - Niels Decher
- Institute of Physiology and Pathophysiology, Vegetative Physiology, Phillips University, Marburg, Germany
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Zobeiri M, Chaudhary R, Datunashvili M, Heuermann RJ, Lüttjohann A, Narayanan V, Balfanz S, Meuth P, Chetkovich DM, Pape HC, Baumann A, van Luijtelaar G, Budde T. Modulation of thalamocortical oscillations by TRIP8b, an auxiliary subunit for HCN channels. Brain Struct Funct 2018; 223:1537-1564. [PMID: 29168010 PMCID: PMC5869905 DOI: 10.1007/s00429-017-1559-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 10/30/2017] [Indexed: 12/16/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated cation (HCN) channels have important functions in controlling neuronal excitability and generating rhythmic oscillatory activity. The role of tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) in regulation of hyperpolarization-activated inward current, I h, in the thalamocortical system and its functional relevance for the physiological thalamocortical oscillations were investigated. A significant decrease in I h current density, in both thalamocortical relay (TC) and cortical pyramidal neurons was found in TRIP8b-deficient mice (TRIP8b-/-). In addition basal cAMP levels in the brain were found to be decreased while the availability of the fast transient A-type K+ current, I A, in TC neurons was increased. These changes were associated with alterations in intrinsic properties and firing patterns of TC neurons, as well as intrathalamic and thalamocortical network oscillations, revealing a significant increase in slow oscillations in the delta frequency range (0.5-4 Hz) during episodes of active-wakefulness. In addition, absence of TRIP8b suppresses the normal desynchronization response of the EEG during the switch from slow-wave sleep to wakefulness. It is concluded that TRIP8b is necessary for the modulation of physiological thalamocortical oscillations due to its direct effect on HCN channel expression in thalamus and cortex and that mechanisms related to reduced cAMP signaling may contribute to the present findings.
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Affiliation(s)
- Mehrnoush Zobeiri
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany.
| | - Rahul Chaudhary
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Maia Datunashvili
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Robert J Heuermann
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Feinberg School of Medicine, Northwestern University, 60611Chicago, USA
| | - Annika Lüttjohann
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Venu Narayanan
- Department of Neurology and Institute of Translational Neurology, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Sabine Balfanz
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | - Patrick Meuth
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Dane M Chetkovich
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Feinberg School of Medicine, Northwestern University, 60611Chicago, USA
| | - Hans-Christian Pape
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany
| | - Arnd Baumann
- Institute of Complex Systems, Zelluläre Biophysik (ICS-4), Forschungszentrum Jülich, 52425, Jülich, Germany
| | | | - Thomas Budde
- Institut für Physiologie I, Westfälische Wilhelms-Universität, 48149, Münster, Germany.
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Riegelhaupt PM, Tibbs GR, Goldstein PA. HCN and K 2P Channels in Anesthetic Mechanisms Research. Methods Enzymol 2018; 602:391-416. [PMID: 29588040 DOI: 10.1016/bs.mie.2018.01.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The ability of a diverse group of agents to produce general anesthesia has long been an area of intense speculation and investigation. Over the past century, we have seen a paradigm shift from proposing that the anesthetized state arises from nonspecific interaction of anesthetics with the lipid membrane to the recognition that the function of distinct, and identifiable, membrane-embedded proteins is dramatically altered in the presence of intravenous and inhaled agents. Among proteinaceous targets, metabotropic and ionotropic receptors garnered much of the attention over the last 30 years, and it is only relatively recently that voltage-gated ion channels have clearly and rigorously been shown to be important molecular targets. In this review, we will consider the experimental issues relevant to two important ion channel anesthetic targets, HCN and K2P.
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Affiliation(s)
| | - Gareth R Tibbs
- Weill Cornell Medical College, New York, NY, United States
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26
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Fisher DW, Luu P, Agarwal N, Kurz JE, Chetkovich DM. Loss of HCN2 leads to delayed gastrointestinal motility and reduced energy intake in mice. PLoS One 2018; 13:e0193012. [PMID: 29466436 PMCID: PMC5821371 DOI: 10.1371/journal.pone.0193012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 02/03/2018] [Indexed: 01/22/2023] Open
Abstract
Hyperpolarization-activated Cyclic Nucleotide-gated (HCN) channels are important regulators of excitability in neural, cardiac, and other pacemaking cells, which are often altered in disease. In mice, loss of HCN2 leads to cardiac dysrhythmias, persistent spike-wave discharges similar to those seen in absence epilepsy, ataxia, tremor, reduced neuropathic and inflammatory pain, antidepressant-like behavior, infertility, and severely restricted growth. While many of these phenotypes have tissue-specific mechanisms, the cause of restricted growth in HCN2 knockout animals remains unknown. Here, we characterize a novel, 3kb insertion mutation of Hcn2 in the Tremor and Reduced Lifespan 2 (TRLS/2J) mouse that leads to complete loss of HCN2 protein, and we show that this mutation causes many phenotypes similar to other mice lacking HCN2 expression. We then demonstrate that while TRLS/2J mice have low blood glucose levels and impaired growth, dysfunction in hormonal secretion from the pancreas, pituitary, and thyroid are unlikely to lead to this phenotype. Instead, we find that homozygous TRLS/2J mice have abnormal gastrointestinal function that is characterized by less food consumption and delayed gastrointestinal transit as compared to wildtype mice. In summary, a novel mutation in HCN2 likely leads to impaired GI motility, causing the severe growth restriction seen in mice with mutations that eliminate HCN2 expression.
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Affiliation(s)
- Daniel W. Fisher
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
| | - Phillip Luu
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
| | - Neha Agarwal
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
| | - Jonathan E. Kurz
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
| | - Dane M. Chetkovich
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University Feinberg School of Medicine, Chicago, IL, United States of America
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States of America
- * E-mail:
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27
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Kato AS, Witkin JM. Protein complexes as psychiatric and neurological drug targets. Biochem Pharmacol 2018; 151:263-281. [PMID: 29330067 DOI: 10.1016/j.bcp.2018.01.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 01/05/2018] [Indexed: 12/25/2022]
Abstract
The need for improved medications for psychiatric and neurological disorders is clear. Difficulties in finding such drugs demands that all strategic means be utilized for their invention. The discovery of forebrain specific AMPA receptor antagonists, which selectively block the specific combinations of principal and auxiliary subunits present in forebrain regions but spare targets in the cerebellum, was recently disclosed. This discovery raised the possibility that other auxiliary protein systems could be utilized to help identify new medicines. Discussion of the TARP-dependent AMPA receptor antagonists has been presented elsewhere. Here we review the diversity of protein complexes of neurotransmitter receptors in the nervous system to highlight the broad range of protein/protein drug targets. We briefly outline the structural basis of protein complexes as drug targets for G-protein-coupled receptors, voltage-gated ion channels, and ligand-gated ion channels. This review highlights heterodimers, subunit-specific receptor constructions, multiple signaling pathways, and auxiliary proteins with an emphasis on the later. We conclude that the use of auxiliary proteins in chemical compound screening could enhance the detection of specific, targeted drug searches and lead to novel and improved medicines for psychiatric and neurological disorders.
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Affiliation(s)
- Akihiko S Kato
- Neuroscience Discovery, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA.
| | - Jeffrey M Witkin
- Neuroscience Discovery, Lilly Research Labs, Eli Lilly and Company, Indianapolis, IN, USA
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28
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Estévez R, Elorza-Vidal X, Gaitán-Peñas H, Pérez-Rius C, Armand-Ugón M, Alonso-Gardón M, Xicoy-Espaulella E, Sirisi S, Arnedo T, Capdevila-Nortes X, López-Hernández T, Montolio M, Duarri A, Teijido O, Barrallo-Gimeno A, Palacín M, Nunes V. Megalencephalic leukoencephalopathy with subcortical cysts: A personal biochemical retrospective. Eur J Med Genet 2018; 61:50-60. [DOI: 10.1016/j.ejmg.2017.10.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/14/2017] [Accepted: 10/22/2017] [Indexed: 12/22/2022]
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29
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James ZM, Zagotta WN. Structural insights into the mechanisms of CNBD channel function. J Gen Physiol 2017; 150:225-244. [PMID: 29233886 PMCID: PMC5806680 DOI: 10.1085/jgp.201711898] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 11/28/2017] [Indexed: 12/28/2022] Open
Abstract
James and Zagotta discuss how recent cryoEM structures inform our understanding of cyclic nucleotide–binding domain channels. Cyclic nucleotide-binding domain (CNBD) channels are a family of ion channels in the voltage-gated K+ channel superfamily that play crucial roles in many physiological processes. CNBD channels are structurally similar but functionally very diverse. This family includes three subfamilies: (1) the cyclic nucleotide-gated (CNG) channels, which are cation-nonselective, voltage-independent, and cyclic nucleotide-gated; (2) the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels, which are weakly K+ selective, hyperpolarization-activated, and cyclic nucleotide-gated; and (3) the ether-à-go-go-type (KCNH) channels, which are strongly K+ selective, depolarization-activated, and cyclic nucleotide-independent. Recently, several high-resolution structures have been reported for intact CNBD channels, providing a structural framework to better understand their diverse function. In this review, we compare and contrast the recent structures and discuss how they inform our understanding of ion selectivity, voltage-dependent gating, and cyclic nucleotide–dependent gating within this channel family.
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Affiliation(s)
- Zachary M James
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
| | - William N Zagotta
- Department of Physiology and Biophysics, University of Washington, Seattle, WA
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30
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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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31
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Plasticity of intrinsic excitability during LTD is mediated by bidirectional changes in h-channel activity. Sci Rep 2017; 7:14418. [PMID: 29089586 PMCID: PMC5663755 DOI: 10.1038/s41598-017-14874-z] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 10/18/2017] [Indexed: 11/12/2022] Open
Abstract
The polarity of excitability changes associated with induction of Long-Term synaptic Depression (LTD) in CA1 pyramidal neurons is a contentious issue. Postsynaptic neuronal excitability after LTD induction is found to be reduced in certain cases (i.e. synergistic changes) but enhanced in others (i.e. compensatory or homeostatic). We examined here whether these divergent findings could result from the activation of two separate mechanisms converging onto a single learning rule linking synergistic and homeostatic plasticity. We show that the magnitude of LTD induced with low frequency stimulation (LFS) of the Schaffer collaterals determines the polarity of intrinsic changes in CA1 pyramidal neurons. Apparent input resistance (Rin) is reduced following induction of moderate LTD (<20–30%). In contrast, Rin is increased after induction of large LTD (>40%) induced by repetitive episodes of LFS. The up-regulation of Ih observed after moderate LTD results from the activation of NMDA receptors whereas the down-regulation of Ih is due to activation of mGluR1 receptors. These changes in Rin were associated with changes in intrinsic excitability. In conclusion, our study indicates that changes in excitability after LTD induction follow a learning rule describing a continuum linking synergistic and compensatory changes in excitability.
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32
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Hayoz S, Tiwari PB, Piszczek G, Üren A, Brelidze TI. Investigating cyclic nucleotide and cyclic dinucleotide binding to HCN channels by surface plasmon resonance. PLoS One 2017; 12:e0185359. [PMID: 28950029 PMCID: PMC5614581 DOI: 10.1371/journal.pone.0185359] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/11/2017] [Indexed: 11/19/2022] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-modulated (HCN) channels control cardiac and neuronal rhythmicity. HCN channels contain cyclic nucleotide-binding domain (CNBD) in their C-terminal region linked to the pore-forming transmembrane segment with a C-linker. The C-linker couples the conformational changes caused by the direct binding of cyclic nucleotides to the HCN pore opening. Recently, cyclic dinucleotides were shown to antagonize the effect of cyclic nucleotides in HCN4 but not in HCN2 channels. Based on the structural analysis and mutational studies it has been proposed that cyclic dinucleotides affect HCN4 channels by binding to the C-linker pocket (CLP). Here, we first show that surface plasmon resonance (SPR) can be used to accurately measure cyclic nucleotide binding affinity to the C-linker/CNBD of HCN2 and HCN4 channels. We then used SPR to investigate cyclic dinucleotide binding in HCN channels. To our surprise, we detected no binding of cyclic dinucleotides to the isolated monomeric C-linker/CNBDs of HCN4 channels with SPR. The binding of cyclic dinucleotides was further examined with isothermal calorimetry (ITC), which indicated no binding of cyclic dinucleotides to both monomeric and tetrameric C-linker/CNBDs of HCN4 channels. Taken together, our results suggest that interaction of the C-linker/CNBD with other parts of the channel is necessary for cyclic-dinucleotide binding in HCN4 channels.
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Affiliation(s)
- Sebastien Hayoz
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Purushottam B. Tiwari
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Grzegorz Piszczek
- Biophysics Core, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, United States of America
| | - Aykut Üren
- Department of Oncology, Georgetown University Medical Center, Washington, DC, United States of America
| | - Tinatin I. Brelidze
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States of America
- * E-mail:
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Lyman KA, Han Y, Heuermann RJ, Cheng X, Kurz JE, Lyman RE, Van Veldhoven PP, Chetkovich DM. Allostery between two binding sites in the ion channel subunit TRIP8b confers binding specificity to HCN channels. J Biol Chem 2017; 292:17718-17730. [PMID: 28887304 DOI: 10.1074/jbc.m117.802256] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 09/05/2017] [Indexed: 12/20/2022] Open
Abstract
Tetratricopeptide repeat (TPR) domains are ubiquitous structural motifs that mediate protein-protein interactions. For example, the TPR domains in the peroxisomal import receptor PEX5 enable binding to a range of type 1 peroxisomal targeting signal motifs. A homolog of PEX5, tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b), binds to and functions as an auxiliary subunit of hyperpolarization-activated cyclic nucleotide (HCN)-gated channels. Given the similarity between TRIP8b and PEX5, this difference in function raises the question of what mechanism accounts for their binding specificity. In this report, we found that the cyclic nucleotide-binding domain and the C terminus of the HCN channel are critical for conferring specificity to TRIP8b binding. We show that TRIP8b binds the HCN cyclic nucleotide-binding domain through a 37-residue domain and the HCN C terminus through the TPR domains. Using a combination of fluorescence polarization- and co-immunoprecipitation-based assays, we establish that binding at either site increases affinity at the other. Thus, allosteric coupling of the TRIP8b TPR domains both promotes binding to HCN channels and limits binding to type 1 peroxisomal targeting signal substrates. These results raise the possibility that other TPR domains may be similarly influenced by allosteric mechanisms as a general feature of protein-protein interactions.
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Affiliation(s)
- Kyle A Lyman
- From the Davee Department of Neurology and Clinical Neurosciences and
| | - Ye Han
- From the Davee Department of Neurology and Clinical Neurosciences and
| | | | - Xiangying Cheng
- From the Davee Department of Neurology and Clinical Neurosciences and
| | | | - Reagan E Lyman
- From the Davee Department of Neurology and Clinical Neurosciences and
| | - Paul P Van Veldhoven
- the Laboratory of Lipid Biochemistry and Protein Interactions, Campus Gasthuisberg, KU Leuven, 3000 Leuven, Belgium
| | - Dane M Chetkovich
- From the Davee Department of Neurology and Clinical Neurosciences and .,Physiology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611 and
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Bankston JR, DeBerg HA, Stoll S, Zagotta WN. Mechanism for the inhibition of the cAMP dependence of HCN ion channels by the auxiliary subunit TRIP8b. J Biol Chem 2017; 292:17794-17803. [PMID: 28864772 DOI: 10.1074/jbc.m117.800722] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 08/29/2017] [Indexed: 11/06/2022] Open
Abstract
TRIP8b, an accessory subunit of hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels, alters both the cell surface expression and cyclic nucleotide dependence of these channels. However, the mechanism by which TRIP8b exerts these dual effects is still poorly understood. In addition to binding to the carboxyl-terminal tripeptide of HCN channels, TRIP8b also binds directly to the cyclic nucleotide-binding domain (CNBD). That interaction, which requires a small central portion of TRIP8b termed TRIP8bcore, is both necessary and sufficient for reducing the cAMP-dependent regulation of HCN channels. Here, using fluorescence anisotropy, we report that TRIP8b binding to the CNBD of HCN2 channels decreases the apparent affinity of cAMP for the CNBD. We explored two possible mechanisms for this inhibition. A noncompetitive mechanism in which TRIP8b inhibits the conformational change of the CNBD associated with cAMP regulation and a competitive mechanism in which TRIP8b and cAMP compete for the same binding site. To test these two mechanisms, we used a combination of fluorescence anisotropy, biolayer interferometry, and double electron-electron resonance spectroscopy. Fitting these models to our fluorescence anisotropy binding data revealed that, surprisingly, the TRIP8b-dependent reduction of cAMP binding to the CNBD can largely be explained by partial competition between TRIP8b and cAMP. On the basis of these findings, we propose that TRIP8b competes with a portion of the cAMP-binding site or distorts the binding site by making interactions with the binding pocket, thus acting predominantly as a competitive antagonist that inhibits the cyclic-nucleotide dependence of HCN channels.
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Affiliation(s)
| | - Hannah A DeBerg
- From the Departments of Physiology and Biophysics and.,Chemistry, University of Washington, Seattle, Washington 98195
| | - Stefan Stoll
- Chemistry, University of Washington, Seattle, Washington 98195
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35
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Han Y, Heuermann RJ, Lyman KA, Fisher D, Ismail QA, Chetkovich DM. HCN-channel dendritic targeting requires bipartite interaction with TRIP8b and regulates antidepressant-like behavioral effects. Mol Psychiatry 2017; 22:458-465. [PMID: 27400855 PMCID: PMC5233690 DOI: 10.1038/mp.2016.99] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/25/2016] [Accepted: 05/10/2016] [Indexed: 12/29/2022]
Abstract
Major depressive disorder (MDD) is a prevalent psychiatric condition with limited therapeutic options beyond monoaminergic therapies. Although effective in some individuals, many patients fail to respond adequately to existing treatments, and new pharmacologic targets are needed. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate excitability in neurons, and blocking HCN channel function has been proposed as a novel antidepressant strategy. However, systemic blockade of HCN channels produces cardiac effects that limit this approach. Knockout (KO) of the brain-specific HCN-channel auxiliary subunit tetratricopeptide repeat-containing Rab8b-interacting protein (TRIP8b) also produces antidepressant-like behavioral effects and suggests that inhibiting TRIP8b function could produce antidepressant-like effects without affecting the heart. We examined the structural basis of TRIP8b-mediated HCN-channel trafficking and its relationship with antidepressant-like behavior using a viral rescue approach in TRIP8b KO mice. We found that restoring TRIP8b to the hippocampus was sufficient to reverse the impaired HCN-channel trafficking and antidepressant-like behavioral effects caused by TRIP8b KO. Moreover, we found that hippocampal expression of a mutated version of TRIP8b further impaired HCN-channel trafficking and increased the antidepressant-like behavioral phenotype of TRIP8b KO mice. Thus, modulating the TRIP8b-HCN interaction bidirectionally influences channel trafficking and antidepressant-like behavior. Overall, our work suggests that small-molecule inhibitors of the interaction between TRIP8b and HCN should produce antidepressant-like behaviors and could represent a new paradigm for the treatment of MDD.
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Affiliation(s)
- Ye Han
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Robert J. Heuermann
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Kyle A. Lyman
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Daniel Fisher
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Quratul-Ain Ismail
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
| | - Dane M. Chetkovich
- Davee Department of Neurology and Clinical Neurosciences, Northwestern University, Chicago, IL 60611 USA
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36
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The Dendrites of CA2 and CA1 Pyramidal Neurons Differentially Regulate Information Flow in the Cortico-Hippocampal Circuit. J Neurosci 2017; 37:3276-3293. [PMID: 28213444 DOI: 10.1523/jneurosci.2219-16.2017] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 12/27/2016] [Accepted: 02/07/2017] [Indexed: 12/29/2022] Open
Abstract
The impact of a given neuronal pathway depends on the number of synapses it makes with its postsynaptic target, the strength of each individual synapse, and the integrative properties of the postsynaptic dendrites. Here we explore the cellular and synaptic mechanisms responsible for the differential excitatory drive from the entorhinal cortical pathway onto mouse CA2 compared with CA1 pyramidal neurons (PNs). Although both types of neurons receive direct input from entorhinal cortex onto their distal dendrites, these inputs produce a 5- to 6-fold larger EPSP at the soma of CA2 compared with CA1 PNs, which is sufficient to drive action potential output from CA2 but not CA1. Experimental and computational approaches reveal that dendritic propagation is more efficient in CA2 than CA1 as a result of differences in dendritic morphology and dendritic expression of the hyperpolarization-activated cation current (Ih). Furthermore, there are three times as many cortical inputs onto CA2 compared with CA1 PN distal dendrites. Using a computational model, we demonstrate that the differences in dendritic properties of CA2 compared with CA1 PNs are necessary to enable the CA2 PNs to generate their characteristically large EPSPs in response to their cortical inputs; in contrast, CA1 dendritic properties limit the size of the EPSPs they generate, even to a similar number of cortical inputs. Thus, the matching of dendritic integrative properties with the density of innervation is crucial for the differential processing of information from the direct cortical inputs by CA2 compared with CA1 PNs.SIGNIFICANCE STATEMENT Recent discoveries have shown that the long-neglected hippocampal CA2 region has distinct synaptic properties and plays a prominent role in social memory and schizophrenia. This study addresses the puzzling finding that the direct entorhinal cortical inputs to hippocampus, which target the very distal pyramidal neuron dendrites, provide an unusually strong excitatory drive at the soma of CA2 pyramidal neurons, with EPSPs that are 5-6 times larger than those in CA1 pyramidal neurons. We here elucidate synaptic and dendritic mechanisms that account quantitatively for the marked difference in EPSP size. Our findings further demonstrate the general importance of fine-tuning the integrative properties of neuronal dendrites to their density of synaptic innervation.
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37
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Lee CH, MacKinnon R. Structures of the Human HCN1 Hyperpolarization-Activated Channel. Cell 2017; 168:111-120.e11. [PMID: 28086084 DOI: 10.1016/j.cell.2016.12.023] [Citation(s) in RCA: 255] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 11/29/2016] [Accepted: 12/15/2016] [Indexed: 01/23/2023]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels underlie the control of rhythmic activity in cardiac and neuronal pacemaker cells. In HCN, the polarity of voltage dependence is uniquely reversed. Intracellular cyclic adenosine monophosphate (cAMP) levels tune the voltage response, enabling sympathetic nerve stimulation to increase the heart rate. We present cryo-electron microscopy structures of the human HCN channel in the absence and presence of cAMP at 3.5 Å resolution. HCN channels contain a K+ channel selectivity filter-forming sequence from which the amino acids create a unique structure that explains Na+ and K+ permeability. The voltage sensor adopts a depolarized conformation, and the pore is closed. An S4 helix of unprecedented length extends into the cytoplasm, contacts the C-linker, and twists the inner helical gate shut. cAMP binding rotates cytoplasmic domains to favor opening of the inner helical gate. These structures advance understanding of ion selectivity, reversed polarity gating, and cAMP regulation in HCN channels.
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Affiliation(s)
- Chia-Hsueh Lee
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA
| | - Roderick MacKinnon
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA.
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Sharpe EJ, Larson ED, Proenza C. Cyclic AMP reverses the effects of aging on pacemaker activity and If in sinoatrial node myocytes. J Gen Physiol 2017; 149:237-247. [PMID: 28057842 PMCID: PMC5299620 DOI: 10.1085/jgp.201611674] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 11/09/2016] [Accepted: 11/22/2016] [Indexed: 12/19/2022] Open
Abstract
Aging reduces pacemaker activity and shifts the voltage dependence of activation of the funny current, If, in sinoatrial node myocytes. Sharpe et al. find that these effects of aging can be reversed by application of exogenous cAMP but not by stimulation of endogenous cAMP. Aerobic capacity decreases with age, in part because of an age-dependent decline in maximum heart rate (mHR) and a reduction in the intrinsic pacemaker activity of the sinoatrial node of the heart. Isolated sinoatrial node myocytes (SAMs) from aged mice have slower spontaneous action potential (AP) firing rates and a hyperpolarizing shift in the voltage dependence of activation of the “funny current,” If. Cyclic AMP (cAMP) is a critical modulator of both AP firing rate and If in SAMs. Here, we test the ability of endogenous and exogenous cAMP to overcome age-dependent changes in acutely isolated murine SAMs. We found that maximal stimulation of endogenous cAMP with 3-isobutyl-1-methylxanthine (IBMX) and forskolin significantly increased AP firing rate and depolarized the voltage dependence of activation of If in SAMs from both young and aged mice. However, these changes were insufficient to overcome the deficits in aged SAMs, and significant age-dependent differences in AP firing rate and If persisted in the presence of IBMX and forskolin. In contrast, the effects of aging on SAMs were completely abolished by a high concentration of exogenous cAMP, which restored AP firing rate and If activation to youthful levels in cells from aged animals. Interestingly, the age-dependent differences in AP firing rates and If were similar in whole-cell and perforated-patch recordings, and the hyperpolarizing shift in If persisted in excised inside-out patches, suggesting a limited role for cAMP in causing these changes. Collectively, the data indicate that aging does not impose an absolute limit on pacemaker activity and that it does not act by simply reducing the concentration of freely diffusible cAMP in SAMs.
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Affiliation(s)
- Emily J Sharpe
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - Eric D Larson
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
| | - Catherine Proenza
- Department of Physiology and Biophysics, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045 .,Department of Medicine, Division of Cardiology, University of Colorado-Anschutz Medical Campus, Aurora, CO 80045
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Itoh M, Ishihara K, Nakashima N, Takano M. The hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contain multiple S-palmitoylation sites. J Physiol Sci 2016; 66:241-8. [PMID: 26546007 PMCID: PMC10717812 DOI: 10.1007/s12576-015-0420-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2015] [Accepted: 10/18/2015] [Indexed: 11/26/2022]
Abstract
Expression of hyperpolarization-activated cyclic nucleotide-gated channels (HCN1-4) on distal dendrites of neurons is suggested to modify synaptic integration in the central nervous system. However, the mechanisms of dendritic localization are not fully understood. Recent studies have revealed that S-palmitoylation plays an important role in the enrichment of various molecules at the postsynaptic membrane. Thus, we performed an acyl-biotinyl exchange assay, and found that HCN1, HCN2, and HCN4, but not HCN3, were S-palmitoylated in HEK293 cells. Mutation of multiple intracellular cysteine residues at the N-terminus of HCN2 was required for complete inhibition of S-palmitoylation. However, this mutagenesis had a minimal effect on surface expression of HCN2 proteins or electrophysiological properties of HCN2 current when expressed in HEK293 cells or in Xenopus oocytes. These findings provide insight into the physiological roles of S-palmitoylation of HCN channels in native neurons.
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Affiliation(s)
- Masayuki Itoh
- Division of Integrated Autonomic Function, Department of Physiology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan.
| | - Keiko Ishihara
- Division of Integrated Autonomic Function, Department of Physiology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan
| | - Noriyuki Nakashima
- Department of Physiology, Faculty of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto, 606-8501, Japan
| | - Makoto Takano
- Division of Integrated Autonomic Function, Department of Physiology, Kurume University School of Medicine, 67 Asahimachi, Kurume, Fukuoka, 830-0011, Japan
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40
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Brennan GP, Baram TZ, Poolos NP. Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) Channels in Epilepsy. Cold Spring Harb Perspect Med 2016; 6:a022384. [PMID: 26931806 DOI: 10.1101/cshperspect.a022384] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Epilepsy is a common brain disorder characterized by the occurrence of spontaneous seizures. These bursts of synchronous firing arise from abnormalities of neuronal networks. Excitability of individual neurons and neuronal networks is largely governed by ion channels and, indeed, abnormalities of a number of ion channels resulting from mutations or aberrant expression and trafficking underlie several types of epilepsy. Here, we focus on the hyperpolarization-activated cyclic nucleotide-gated ion (HCN) channels that conduct Ih current. This conductance plays complex and diverse roles in the regulation of neuronal and network excitability. We describe the normal function of HCN channels and discuss how aberrant expression, assembly, trafficking, and posttranslational modifications contribute to experimental and human epilepsy.
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Affiliation(s)
- Gary P Brennan
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475
| | - Tallie Z Baram
- Department of Pediatrics, University of California-Irvine, Irvine, California 92697-4475 Departments of Anatomy/Neurobiology and Neurology, University of California-Irvine, Irvine, California 92697-4475
| | - Nicholas P Poolos
- Department of Neurology and Regional Epilepsy Center, University of Washington, Seattle, Washington 98104
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Heuermann RJ, Jaramillo TC, Ying SW, Suter BA, Lyman KA, Han Y, Lewis AS, Hampton TG, Shepherd GMG, Goldstein PA, Chetkovich DM. Reduction of thalamic and cortical Ih by deletion of TRIP8b produces a mouse model of human absence epilepsy. Neurobiol Dis 2016; 85:81-92. [PMID: 26459112 PMCID: PMC4688217 DOI: 10.1016/j.nbd.2015.10.005] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Revised: 09/22/2015] [Accepted: 10/08/2015] [Indexed: 12/19/2022] Open
Abstract
Absence seizures occur in several types of human epilepsy and result from widespread, synchronous feedback between the cortex and thalamus that produces brief episodes of loss of consciousness. Genetic rodent models have been invaluable for investigating the pathophysiological basis of these seizures. Here, we identify tetratricopeptide-containing Rab8b-interacting protein (TRIP8b) knockout mice as a new model of absence epilepsy, featuring spontaneous spike-wave discharges on electroencephalography (EEG) that are the electrographic hallmark of absence seizures. TRIP8b is an auxiliary subunit of the hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels, which have previously been implicated in the pathogenesis of absence seizures. In contrast to mice lacking the pore-forming HCN channel subunit HCN2, TRIP8b knockout mice exhibited normal cardiac and motor function and a less severe seizure phenotype. Evaluating the circuit that underlies absence seizures, we found that TRIP8b knockout mice had significantly reduced HCN channel expression and function in thalamic-projecting cortical layer 5b neurons and thalamic relay neurons, but preserved function in inhibitory neurons of the reticular thalamic nucleus. Our results expand the known roles of TRIP8b and provide new insight into the region-specific functions of TRIP8b and HCN channels in constraining cortico-thalamo-cortical excitability.
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Affiliation(s)
- Robert J Heuermann
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Thomas C Jaramillo
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Shui-Wang Ying
- C.V. Starr Laboratory for Molecular Neuropharmacology, Department of Anesthesiology, Weill Medical College of Cornell University, 1300 York Ave., Room A-1050, New York, New York 10021, USA.
| | - Benjamin A Suter
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Kyle A Lyman
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Ye Han
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Alan S Lewis
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Thomas G Hampton
- Mouse Specifics, Inc., 2 Central Street, Level 1 Suite 1, Framingham, MA 01701, USA.
| | - Gordon M G Shepherd
- Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
| | - Peter A Goldstein
- C.V. Starr Laboratory for Molecular Neuropharmacology, Department of Anesthesiology, Weill Medical College of Cornell University, 1300 York Ave., Room A-1050, New York, New York 10021, USA.
| | - Dane M Chetkovich
- Davee Department of Neurology and Clinical Neurosciences, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA; Department of Physiology, Feinberg School of Medicine, Northwestern University, 303 E. Chicago Ave., Ward Building, Room 10-201, Chicago, IL 60611, USA.
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Novella Romanelli M, Sartiani L, Masi A, Mannaioni G, Manetti D, Mugelli A, Cerbai E. HCN Channels Modulators: The Need for Selectivity. Curr Top Med Chem 2016; 16:1764-91. [PMID: 26975509 PMCID: PMC5374843 DOI: 10.2174/1568026616999160315130832] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2015] [Revised: 08/04/2015] [Accepted: 08/05/2015] [Indexed: 12/27/2022]
Abstract
Hyperpolarization-activated, cyclic nucleotide-gated (HCN) channels, the molecular correlate of the hyperpolarization-activated current (If/Ih), are membrane proteins which play an important role in several physiological processes and various pathological conditions. In the Sino Atrial Node (SAN) HCN4 is the target of ivabradine, a bradycardic agent that is, at the moment, the only drug which specifically blocks If. Nevertheless, several other pharmacological agents have been shown to modulate HCN channels, a property that may contribute to their therapeutic activity and/or to their side effects. HCN channels are considered potential targets for developing drugs to treat several important pathologies, but a major issue in this field is the discovery of isoform-selective compounds, owing to the wide distribution of these proteins into the central and peripheral nervous systems, heart and other peripheral tissues. This survey is focused on the compounds that have been shown, or have been designed, to interact with HCN channels and on their binding sites, with the aim to summarize current knowledge and possibly to unveil useful information to design new potent and selective modulators.
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Affiliation(s)
- Maria Novella Romanelli
- University of Florence, Department of Neurosciences, Psychology, Drug Research and Child's Health, Section of Pharmaceutical and Nutraceutical Sciences, via Ugo Schiff 6, 50019 Sesto Fiorentino, Italy.
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Modular composition and dynamics of native GABAB receptors identified by high-resolution proteomics. Nat Neurosci 2015; 19:233-42. [PMID: 26691831 DOI: 10.1038/nn.4198] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Accepted: 11/16/2015] [Indexed: 01/04/2023]
Abstract
GABAB receptors, the most abundant inhibitory G protein-coupled receptors in the mammalian brain, display pronounced diversity in functional properties, cellular signaling and subcellular distribution. We used high-resolution functional proteomics to identify the building blocks of these receptors in the rodent brain. Our analyses revealed that native GABAB receptors are macromolecular complexes with defined architecture, but marked diversity in subunit composition: the receptor core is assembled from GABAB1a/b, GABAB2, four KCTD proteins and a distinct set of G-protein subunits, whereas the receptor's periphery is mostly formed by transmembrane proteins of different classes. In particular, the periphery-forming constituents include signaling effectors, such as Cav2 and HCN channels, and the proteins AJAP1 and amyloid-β A4, both of which tightly associate with the sushi domains of GABAB1a. Our results unravel the molecular diversity of GABAB receptors and their postnatal assembly dynamics and provide a roadmap for studying the cellular signaling of this inhibitory neurotransmitter receptor.
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Wemhöner K, Kanyshkova T, Silbernagel N, Fernandez-Orth J, Bittner S, Kiper AK, Rinné S, Netter MF, Meuth SG, Budde T, Decher N. An N-terminal deletion variant of HCN1 in the epileptic WAG/Rij strain modulates HCN current densities. Front Mol Neurosci 2015; 8:63. [PMID: 26578877 PMCID: PMC4630678 DOI: 10.3389/fnmol.2015.00063] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 10/13/2015] [Indexed: 11/26/2022] Open
Abstract
Rats of the Wistar Albino Glaxo/Rij (WAG/Rij) strain show symptoms resembling human absence epilepsy. Thalamocortical neurons of WAG/Rij rats are characterized by an increased HCN1 expression, a negative shift in Ih activation curve, and an altered responsiveness of Ih to cAMP. We cloned HCN1 channels from rat thalamic cDNA libraries of the WAG/Rij strain and found an N-terminal deletion of 37 amino acids. In addition, WAG-HCN1 has a stretch of six amino acids, directly following the deletion, where the wild-type sequence (GNSVCF) is changed to a polyserine motif. These alterations were found solely in thalamus mRNA but not in genomic DNA. The truncated WAG-HCN1 was detected late postnatal in WAG/Rij rats and was not passed on to rats obtained from pairing WAG/Rij and non-epileptic August Copenhagen Irish rats. Heterologous expression in Xenopus oocytes revealed 2.2-fold increased current amplitude of WAG-HCN1 compared to rat HCN1. While WAG-HCN1 channels did not have altered current kinetics or changed regulation by protein kinases, fluorescence imaging revealed a faster and more pronounced surface expression of WAG-HCN1. Using co-expression experiments, we found that WAG-HCN1 channels suppress heteromeric HCN2 and HCN4 currents. Moreover, heteromeric channels of WAG-HCN1 with HCN2 have a reduced cAMP sensitivity. Functional studies revealed that the gain-of-function of WAG-HCN1 is not caused by the N-terminal deletion alone, thus requiring a change of the N-terminal GNSVCF motif. Our findings may help to explain previous observations in neurons of the WAG/Rij strain and indicate that WAG-HCN1 may contribute to the genesis of absence seizures in WAG/Rij rats.
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Affiliation(s)
- Konstantin Wemhöner
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Tatyana Kanyshkova
- Institute for Physiology I, Westfälische Wilhelms-Universität Münster, Germany
| | - Nicole Silbernagel
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | | | - Stefan Bittner
- Department of Neurology, University Medical Center, Johannes Gutenberg-University Mainz Mainz, Germany
| | - Aytug K Kiper
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Susanne Rinné
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Michael F Netter
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
| | - Sven G Meuth
- Department of Neurology, Westfälische Wilhelms-Universität Münster, Germany
| | - Thomas Budde
- Institute for Physiology I, Westfälische Wilhelms-Universität Münster, Germany
| | - Niels Decher
- Institute for Physiology and Pathophysiology, Vegetative Physiology, Philipps-University of Marburg Marburg, Germany
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Engel D, Seutin V. High dendritic expression of Ih in the proximity of the axon origin controls the integrative properties of nigral dopamine neurons. J Physiol 2015; 593:4905-22. [PMID: 26350173 DOI: 10.1113/jp271052] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 08/26/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The hyperpolarization-activated cation current Ih is expressed in dopamine neurons of the substantia nigra, but the subcellular distribution of the current and its role in synaptic integration remain unknown. We used cell-attached patch recordings to determine the localization profile of Ih along the somatodendritic axis of nigral dopamine neurons in slices from young rats. Ih density is higher in axon-bearing dendrites, in a membrane area close to the axon origin, than in the soma and axon-lacking dendrites. Dual current-clamp recordings revealed a similar contribution of Ih to the waveform of single excitatory postsynaptic potentials throughout the somatodendritic domain. The Ih blocker ZD 7288 increased the temporal summation in all dendrites with a comparable effect in axon- and non-axon dendrites. The strategic position of Ih in the proximity of the axon may influence importantly transitions between pacemaker and bursting activities and consequently the downstream release of dopamine. ABSTRACT Dendrites of most neurons express voltage-gated ion channels in their membrane. In combination with passive properties, active currents confer to dendrites a high computational potential. The hyperpolarization-activated cation current Ih present in the dendrites of some pyramidal neurons affects their membrane and integration properties, synaptic plasticity and higher functions such as memory. A gradient of increasing h-channel density towards distal dendrites has been found to be responsible for the location independence of excitatory postsynaptic potential (EPSP) waveform and temporal summation in cortical and hippocampal pyramidal cells. However, reports on other cell types revealed that smoother gradients or even linear distributions of Ih can achieve homogeneous temporal summation. Although the existence of a robust, slowly activating Ih current has been repeatedly demonstrated in nigral dopamine neurons, its subcellular distribution and precise role in synaptic integration are unknown. Using cell-attached patch-clamp recordings, we find a higher Ih current density in the axon-bearing dendrite than in the soma or in dendrites without axon in nigral dopamine neurons. Ih is mainly concentrated in the dendritic membrane area surrounding the axon origin and decreases with increasing distances from this site. Single EPSPs and temporal summation are similarly affected by blockade of Ih in axon- and non-axon-bearing dendrites. The presence of Ih close to the axon is pivotal to control the integrative functions and the output signal of dopamine neurons and may consequently influence the downstream coding of movement.
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Affiliation(s)
- Dominique Engel
- GIGA-Neurosciences, Neurophysiology Unit, University of Liège, SartTilman, B-4000, Liège, Belgium
| | - Vincent Seutin
- GIGA-Neurosciences, Neurophysiology Unit, University of Liège, SartTilman, B-4000, Liège, Belgium
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Han Y, Lyman K, Clutter M, Schiltz GE, Ismail QA, Prados DB, Luan CH, Chetkovich DM. Identification of Small-Molecule Inhibitors of Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels. ACTA ACUST UNITED AC 2015; 20:1124-31. [PMID: 26045196 DOI: 10.1177/1087057115589590] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Accepted: 05/11/2015] [Indexed: 12/28/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels function in the brain to limit neuronal excitability. Limiting the activity of these channels has been proposed as a therapy for major depressive disorder, but the critical role of HCN channels in cardiac pacemaking has limited efforts to develop therapies directed at the channel. Previous studies indicated that the function of HCN is tightly regulated by its auxiliary subunit, tetratricopeptide repeat-containing Rab8b interacting protein (TRIP8b), which is not expressed in the heart. To target the function of the HCN channel in the brain without affecting the channel's function in the heart, we propose disrupting the interaction between HCN and TRIP8b. We developed a high-throughput fluorescence polarization (FP) assay to identify small molecules capable of disrupting this interaction. We used this FP assay to screen a 20,000-compound library and identified a number of active compounds. The active compounds were validated using an orthogonal AlphaScreen assay to identify one compound (0.005%) as the first confirmed hit for inhibiting the HCN-TRIP8b interaction. Identifying small molecules capable of disrupting the interaction between HCN and TRIP8b should enable the development of new research tools and small-molecule therapies that could benefit patients with depression.
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Affiliation(s)
- Ye Han
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Northwestern University, Chicago, IL, USA
| | - Kyle Lyman
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Northwestern University, Chicago, IL, USA
| | - Matt Clutter
- Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL, USA
| | - Gary E Schiltz
- Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL, USA
| | - Quratul-Ain Ismail
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Northwestern University, Chicago, IL, USA
| | - Diego Bleifuss Prados
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Northwestern University, Chicago, IL, USA
| | - Chi-Hao Luan
- High Throughput Analysis Laboratory and Department of Molecular Biosciences, Northwestern University, Evanston, IL, USA
| | - Dane M Chetkovich
- Davee Department of Neurology and Clinical Neurosciences and Department of Physiology, Northwestern University, Chicago, IL, USA
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47
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DeBerg HA, Bankston JR, Rosenbaum JC, Brzovic PS, Zagotta WN, Stoll S. Structural mechanism for the regulation of HCN ion channels by the accessory protein TRIP8b. Structure 2015; 23:734-44. [PMID: 25800552 DOI: 10.1016/j.str.2015.02.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/13/2015] [Accepted: 02/09/2015] [Indexed: 11/19/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) ion channels underlie the cationic Ih current present in many neurons. The direct binding of cyclic AMP to HCN channels increases the rate and extent of channel opening and results in a depolarizing shift in the voltage dependence of activation. TRIP8b is an accessory protein that regulates the cell surface expression and dendritic localization of HCN channels and reduces the cyclic nucleotide dependence of these channels. Here, we use electron paramagnetic resonance (EPR) to show that TRIP8b binds to the apo state of the cyclic nucleotide binding domain (CNBD) of HCN2 channels without changing the overall domain structure. With EPR and nuclear magnetic resonance, we locate TRIP8b relative to the HCN channel and identify the binding interface on the CNBD. These data provide a structural framework for understanding how TRIP8b regulates the cyclic nucleotide dependence of HCN channels.
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Affiliation(s)
- Hannah A DeBerg
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA; Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - John R Bankston
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Joel C Rosenbaum
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - Peter S Brzovic
- Department of Biochemistry, University of Washington, Seattle, WA 98195, USA
| | - William N Zagotta
- Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA
| | - Stefan Stoll
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA.
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48
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Abstract
Voltage- and ligand-gated ion channels form the molecular basis of cellular excitability. With >400 members and accounting for ∼1.5% of the human genome, ion channels are some of the most well studied of all proteins in heterologous expression systems. Yet, ion channels often exhibit unexpected properties in vivo because of their interaction with a variety of signaling/scaffolding proteins. Such interactions can influence the function and localization of ion channels, as well as their coupling to intracellular second messengers and pathways, thus increasing the signaling potential of these ion channels in neurons. Moreover, functions have been ascribed to ion channels that are largely independent of their ion-conducting roles. Molecular and functional dissection of the ion channel proteome/interactome has yielded new insights into the composition of ion channel complexes and how their dysregulation leads to human disease.
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49
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Herrmann S, Schnorr S, Ludwig A. HCN channels--modulators of cardiac and neuronal excitability. Int J Mol Sci 2015; 16:1429-47. [PMID: 25580535 PMCID: PMC4307311 DOI: 10.3390/ijms16011429] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2014] [Accepted: 12/31/2014] [Indexed: 01/06/2023] Open
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels comprise a family of cation channels activated by hyperpolarized membrane potentials and stimulated by intracellular cyclic nucleotides. The four members of this family, HCN1-4, show distinct biophysical properties which are most evident in the kinetics of activation and deactivation, the sensitivity towards cyclic nucleotides and the modulation by tyrosine phosphorylation. The four isoforms are differentially expressed in various excitable tissues. This review will mainly focus on recent insights into the functional role of the channels apart from their classic role as pacemakers. The importance of HCN channels in the cardiac ventricle and ventricular hypertrophy will be discussed. In addition, their functional significance in the peripheral nervous system and nociception will be examined. The data, which are mainly derived from studies using transgenic mice, suggest that HCN channels contribute significantly to cellular excitability in these tissues. Remarkably, the impact of the channels is clearly more pronounced in pathophysiological states including ventricular hypertrophy as well as neural inflammation and neuropathy suggesting that HCN channels may constitute promising drug targets in the treatment of these conditions. This perspective as well as the current therapeutic use of HCN blockers will also be addressed.
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Affiliation(s)
- Stefan Herrmann
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Sabine Schnorr
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
| | - Andreas Ludwig
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, 91054 Erlangen, Germany.
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Zhou M, Luo P, Lu Y, Li CJ, Wang DS, Lu Q, Xu XL, He Z, Guo LJ. Imbalance of HCN1 and HCN2 expression in hippocampal CA1 area impairs spatial learning and memory in rats with chronic morphine exposure. Prog Neuropsychopharmacol Biol Psychiatry 2015; 56:207-14. [PMID: 25301101 DOI: 10.1016/j.pnpbp.2014.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Revised: 09/13/2014] [Accepted: 09/29/2014] [Indexed: 12/12/2022]
Abstract
The hyperpolarization-activated cyclic-nucleotide-gated non-selective cation (HCN) channels play a vital role in the neurological basis underlying nervous system diseases. However, the role of HCN channels in drug addiction is not fully understood. In the present study, we investigated the expression of HCN1 and HCN2 subunits in hippocampal CA1 and the potential molecular mechanisms underlying the modulation of HCN channels in rats with chronic morphine exposure with approaches of electrophysiology, water maze, and Western blotting. We found that chronic morphine exposure (5 mg/kg, sc, for 7 days) caused an inhibition of long-term potentiation (LTP) and impairment of spatial learning and memory, which is associated with a decrease in HCN1, and an increase in HCN2 on cell membrane of hippocampal CA1 area. Additional experiments showed that the imbalance of cell membrane HCN1 and HCN2 expression under chronic morphine exposure was related to an increase in expression of TPR containing Rab8b interacting protein (TRIP8b) (1a-4) and TRIP8b (1b-2), and phosphorylation of protein kinase A (PKA) and adaptor protein 2 μ2 (AP2 μ2). Our results demonstrate the novel information that drug addiction-induced impairment of learning and memory is involved in the imbalance of HCN1 and HCN2 subunits, which is mediated by activation of TRIP8b (1a-4), TRIP8b (1b-2), PKA and AP2 μ2.
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Affiliation(s)
- Mei Zhou
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Pan Luo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Yun Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Chang-jun Li
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Dian-shi Wang
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Qing Lu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Xu-lin Xu
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China
| | - Zhi He
- Department of Neuropsychopharmacology, Medical School of China Three Gorges University, Yichang, 443002, China.
| | - Lian-jun Guo
- Department of Pharmacology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China; Institute of Brain Research, Huazhong University of Science and Technology, Wuhan 430030, China.
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