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Houdayer C, Phillips AM, Chabbert M, Bourreau J, Maroofian R, Houlden H, Richards K, Saadi NW, Dad'ová E, Van Bogaert P, Rupin M, Keren B, Charles P, Smol T, Riquet A, Pais L, O'Donnell-Luria A, VanNoy GE, Bayat A, Møller RS, Olofsson K, Abou Jamra R, Syrbe S, Dasouki M, Seaver LH, Sullivan JA, Shashi V, Alkuraya FS, Poss AF, Spence JE, Schnur RE, Forster IC, Mckenzie CE, Simons C, Wang M, Snell P, Kothur K, Buckley M, Roscioli T, Elserafy N, Dauriat B, Procaccio V, Henrion D, Lenaers G, Colin E, Verbeek NE, Van Gassen KL, Legendre C, Bonneau D, Reid CA, Howell KB, Ziegler A, Legros C. Mono and biallelic variants in HCN2 cause severe neurodevelopmental disorders. MEDRXIV : THE PREPRINT SERVER FOR HEALTH SCIENCES 2024:2024.03.19.24303984. [PMID: 38562733 PMCID: PMC10984036 DOI: 10.1101/2024.03.19.24303984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Hyperpolarization activated Cyclic Nucleotide (HCN) gated channels are crucial for various neurophysiological functions, including learning and sensory functions, and their dysfunction are responsible for brain disorders, such as epilepsy. To date, HCN2 variants have only been associated with mild epilepsy and recently, one monoallelic missense variant has been linked to developmental and epileptic encephalopathy. Here, we expand the phenotypic spectrum of HCN2- related disorders by describing twenty-one additional individuals from fifteen unrelated families carrying HCN2 variants. Seventeen individuals had developmental delay/intellectual disability (DD/ID), two had borderline DD/ID, and one had borderline DD. Ten individuals had epilepsy with DD/ID, with median age of onset of 10 months, and one had epilepsy with normal development. Molecular diagnosis identified thirteen different pathogenic HCN2 variants, including eleven missense variants affecting highly conserved amino acids, one frameshift variant, and one in-frame deletion. Seven variants were monoallelic of which five occurred de novo, one was not maternally inherited, one was inherited from a father with mild learning disabilities, and one was of unknown inheritance. The remaining six variants were biallelic, with four homozygous and two compound heterozygous variants. Functional studies using two-electrode voltage-clamp recordings in Xenopus laevis oocytes were performed on three monoallelic variants, p.(Arg324His), p.(Ala363Val), and p.(Met374Leu), and three biallelic variants, p.(Leu377His), p.(Pro493Leu) and p.(Gly587Asp). The p.(Arg324His) variant induced a strong increase of HCN2 conductance, while p.(Ala363Val) and p.(Met374Leu) displayed dominant negative effects, leading to a partial loss of HCN2 channel function. By confocal imaging, we found that the p.(Leu377His), p.(Pro493Leu) and p.(Gly587Asp) pathogenic variants impaired membrane trafficking, resulting in a complete loss of HCN2 elicited currents in Xenopus oocytes. Structural 3D-analysis in depolarized and hyperpolarized states of HCN2 channels, revealed that the pathogenic variants p.(His205Gln), p.(Ser409Leu), p.(Arg324Cys), p.(Asn369Ser) and p.(Gly460Asp) modify molecular interactions altering HCN2 function. Taken together, our data broadens the clinical spectrum associated with HCN2 variants, and disclose that HCN2 is involved in developmental encephalopathy with or without epilepsy.
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Jin Y, Mao Y, Chen D, Tai Y, Hu R, Yang CL, Zhou J, Chen L, Liu X, Gu E, Jia C, Zhang Z, Tao W. Thalamocortical circuits drive remifentanil-induced postoperative hyperalgesia. J Clin Invest 2022; 132:158742. [PMID: 36519547 PMCID: PMC9754001 DOI: 10.1172/jci158742] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 10/18/2022] [Indexed: 12/15/2022] Open
Abstract
Remifentanil-induced hyperalgesia (RIH) is a severe but common postoperative clinical problem with elusive underlying neural mechanisms. Here, we discovered that glutamatergic neurons in the thalamic ventral posterolateral nucleus (VPLGlu) exhibited significantly elevated burst firing accompanied by upregulation of Cav3.1 T-type calcium channel expression and function in RIH model mice. In addition, we identified a glutamatergic neuronal thalamocortical circuit in the VPL projecting to hindlimb primary somatosensory cortex glutamatergic neurons (S1HLGlu) that mediated RIH. In vivo calcium imaging and multi-tetrode recordings revealed heightened S1HLGlu neuronal activity during RIH. Moreover, preoperative suppression of Cav3.1-dependent burst firing in VPLGlu neurons or chemogenetic inhibition of VPLGlu neuronal terminals in the S1HL abolished the increased S1HLGlu neuronal excitability while alleviating RIH. Our findings suggest that remifentanil induces postoperative hyperalgesia by upregulating T-type calcium channel-dependent burst firing in VPLGlu neurons to activate S1HLGlu neurons, thus revealing an ion channel-mediated neural circuit basis for RIH that can guide analgesic development.
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Affiliation(s)
- Yan Jin
- Stroke Center and Department of Neurology and,Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Yu Mao
- Stroke Center and Department of Neurology and,Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Danyang Chen
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Yingju Tai
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Rui Hu
- Department of Anesthesiology, The Third Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chen-Ling Yang
- Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Jing Zhou
- Department of head, neck, and breast Surgery, Western district of the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Lijian Chen
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Xuesheng Liu
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Erwei Gu
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chunhui Jia
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Zhi Zhang
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Wenjuan Tao
- Stroke Center and Department of Neurology and,Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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Structure of the Human BK Ion Channel in Lipid Environment. MEMBRANES 2022; 12:membranes12080758. [PMID: 36005673 PMCID: PMC9414842 DOI: 10.3390/membranes12080758] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Revised: 07/27/2022] [Accepted: 07/30/2022] [Indexed: 02/04/2023]
Abstract
Voltage-gated and ligand-modulated ion channels play critical roles in excitable cells. To understand the interplay among voltage sensing, ligand binding, and channel opening, the structures of ion channels in various functional states and in lipid membrane environments need to be determined. Here, the random spherically constrained (RSC) single-particle cryo-EM method was employed to study human large conductance voltage- and calcium-activated potassium (hBK or hSlo1) channels reconstituted into liposomes. The hBK structure was determined at 3.5 Å resolution in the absence of Ca2+. Instead of the common fourfold symmetry observed in ligand-modulated ion channels, a twofold symmetry was observed in hBK in liposomes. Compared with the structure of isolated hSlo1 Ca2+ sensing gating rings, two opposing subunits in hBK unfurled, resulting in a wider opening towards the transmembrane region of hBK. In the pore gate domain, two opposing subunits also moved downwards relative to the two other subunits.
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Importance of evaluating protein glycosylation in pluripotent stem cell-derived cardiomyocytes for research and clinical applications. Pflugers Arch 2021; 473:1041-1059. [PMID: 33830329 PMCID: PMC8245383 DOI: 10.1007/s00424-021-02554-x] [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: 11/21/2020] [Revised: 03/01/2021] [Accepted: 03/06/2021] [Indexed: 01/21/2023]
Abstract
Proper protein glycosylation is critical to normal cardiomyocyte physiology. Aberrant glycosylation can alter protein localization, structure, drug interactions, and cellular function. The in vitro differentiation of human pluripotent stem cells into cardiomyocytes (hPSC-CM) has become increasingly important to the study of protein function and to the fields of cardiac disease modeling, drug testing, drug discovery, and regenerative medicine. Here, we offer our perspective on the importance of protein glycosylation in hPSC-CM. Protein glycosylation is dynamic in hPSC-CM, but the timing and extent of glycosylation are still poorly defined. We provide new data highlighting how observed changes in hPSC-CM glycosylation may be caused by underlying differences in the protein or transcript abundance of enzymes involved in building and trimming the glycan structures or glycoprotein gene products. We also provide evidence that alternative splicing results in altered sites of glycosylation within the protein sequence. Our findings suggest the need to precisely define protein glycosylation events that may have a critical impact on the function and maturation state of hPSC-CM. Finally, we provide an overview of analytical strategies available for studying protein glycosylation and identify opportunities for the development of new bioinformatic approaches to integrate diverse protein glycosylation data types. We predict that these tools will promote the accurate assessment of protein glycosylation in future studies of hPSC-CM that will ultimately be of significant experimental and clinical benefit.
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Incorporation of one N-glycosylation-deficient subunit within a tetramer of HCN2 channel is tolerated. Neuroreport 2019; 30:998-1003. [PMID: 31503201 DOI: 10.1097/wnr.0000000000001310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are glycoproteins N-glycosylated at a specific asparagine residue in the S5-S6 linker region. Previous reports suggested that N-glycosylation-deficient HCN2 N380Q (NQ) channels fail to properly target to the plasma membrane and are unable to form functional ion channels. HCN channels are known to homo- and hetero-oligomerize and it is not known whether HCN2-NQ subunits can oligomerize with wild type (wt) N-glycosylated subunits to form a tetrameric assembly. In the present study, homomeric NQ-mutant resulted in no current, cRNA titration experiments controlling the amount of wt-to-NQ injected into Xenopus oocytes indicated that the observed currents were consistent with a model where presence of a single nonglycosylated subunit in a tetrameric oligomer is tolerated forming functional channels. The activation voltage-dependence described by half-activation voltage and slope factor, and the reversal potential of the wt-NQ oligomeric channels were identical to the wt only tetrameric channels. Further incorporation of the nonglycosylated subunit rendered the channels nonconductive or not incorporated into the plasma membrane.
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Terragni B, Scalmani P, Franceschetti S, Cestèle S, Mantegazza M. Post-translational dysfunctions in channelopathies of the nervous system. Neuropharmacology 2017; 132:31-42. [PMID: 28571716 DOI: 10.1016/j.neuropharm.2017.05.028] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Revised: 05/12/2017] [Accepted: 05/26/2017] [Indexed: 12/23/2022]
Abstract
Channelopathies comprise various diseases caused by defects of ion channels. Modifications of their biophysical properties are common and have been widely studied. However, ion channels are heterogeneous multi-molecular complexes that are extensively modulated and undergo a maturation process comprising numerous steps of structural modifications and intracellular trafficking. Perturbations of these processes can give rise to aberrant channels that cause pathologies. Here we review channelopathies of the nervous system associated with dysfunctions at the post-translational level (folding, trafficking, degradation, subcellular localization, interactions with associated proteins and structural post-translational modifications). We briefly outline the physiology of ion channels' maturation and discuss examples of defective mechanisms, focusing in particular on voltage-gated sodium channels, which are implicated in numerous neurological disorders. We also shortly introduce possible strategies to develop therapeutic approaches that target these processes. This article is part of the Special Issue entitled 'Channelopathies.'
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Affiliation(s)
- Benedetta Terragni
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Paolo Scalmani
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Silvana Franceschetti
- U.O. Neurophysiology and Diagnostic Epileptology, Foundation IRCCS Neurological Institute C. Besta, 20133 Milan, Italy
| | - Sandrine Cestèle
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France
| | - Massimo Mantegazza
- Institute of Molecular and Cellular Pharmacology (IPMC), CNRS UMR7275, 06560, Valbonne-Sophia Antipolis, France; University Côte d'Azur (UCA), 06560, Valbonne-Sophia Antipolis, France.
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Thayer DA, Yang SB, Jan YN, Jan LY. N-linked glycosylation of Kv1.2 voltage-gated potassium channel facilitates cell surface expression and enhances the stability of internalized channels. J Physiol 2016; 594:6701-6713. [PMID: 27377235 DOI: 10.1113/jp272394] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 06/09/2016] [Indexed: 01/20/2023] Open
Abstract
KEY POINTS Kv1.2 and related voltage-gated potassium channels have a highly conserved N-linked glycosylation site in the first extracellular loop, with complex glycosylation in COS-7 cells similar to endogenous Kv1.2 glycosylation in hippocampal neurons. COS-7 cells expressing Kv1.2 show a crucial role of this N-linked glycosylation in the forward trafficking of Kv1.2 to the cell membrane. Although both wild-type and non-glycosylated mutant Kv1.2 channels that have reached the cell membrane are internalized at a comparable rate, mutant channels are degraded at a faster rate. Treatment of wild-type Kv1.2 channels on the cell surface with glycosidase to remove sialic acids also results in the faster degradation of internalized channels. Glycosylation of Kv1.2 is important with respect to facilitating trafficking to the cell membrane and enhancing the stability of channels that have reached the cell membrane. ABSTRACT Studies in cultured hippocampal neurons and the COS-7 cell line demonstrate important roles for N-linked glycosylation of Kv1.2 channels in forward trafficking and protein degradation. Kv1.2 channels can contain complex N-linked glycans, which facilitate cell surface expression of the channels. Additionally, the protein stability of cell surface-expressed Kv1.2 channels is affected by glycosylation via differences in the degradation of internalized channels. The present study reveals the importance of N-linked complex glycosylation in boosting Kv1.2 channel density. Notably, sialic acids at the terminal sugar branches play an important role in dampening the degradation of Kv1.2 internalized from the cell membrane to promote its stability.
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Affiliation(s)
- Desiree A Thayer
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA.,Amunix, Mountain View, CA, USA
| | - Shi-Bing Yang
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA.,Institute of Biomedical Sciences, Academia Sinica, Taipei, Taiwan
| | - Yuh Nung Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA
| | - Lily Y Jan
- Howard Hughes Medical Institute, Departments of Physiology, Biochemistry and Biophysics, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California-San Francisco, San Francisco, CA, USA
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