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Lyman KA, Han Y, Robinson AP, Weinberg SE, Fisher DW, Heuermann RJ, Lyman RE, Kim DK, Ludwig A, Chandel NS, Does MD, Miller SD, Chetkovich DM. Characterization of hyperpolarization-activated cyclic nucleotide-gated channels in oligodendrocytes. Front Cell Neurosci 2024; 18:1321682. [PMID: 38469353 PMCID: PMC10925711 DOI: 10.3389/fncel.2024.1321682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2023] [Accepted: 02/08/2024] [Indexed: 03/13/2024] Open
Abstract
Mature oligodendrocytes (OLG) are the myelin-forming cells of the central nervous system. Recent work has shown a dynamic role for these cells in the plasticity of neural circuits, leading to a renewed interest in voltage-sensitive currents in OLG. Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels and their respective current (Ih) were recently identified in mature OLG and shown to play a role in regulating myelin length. Here we provide a biochemical and electrophysiological characterization of HCN channels in cells of the oligodendrocyte lineage. We observed that mice with a nonsense mutation in the Hcn2 gene (Hcn2ap/ap) have less white matter than their wild type counterparts with fewer OLG and fewer oligodendrocyte progenitor cells (OPCs). Hcn2ap/ap mice have severe motor impairments, although these deficits were not observed in mice with HCN2 conditionally eliminated only in oligodendrocytes (Cnpcre/+; Hcn2F/F). However, Cnpcre/+; Hcn2F/F mice develop motor impairments more rapidly in response to experimental autoimmune encephalomyelitis (EAE). We conclude that HCN2 channels in OLG may play a role in regulating metabolism.
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Affiliation(s)
- Kyle A. Lyman
- Department of Neurology, Massachusetts General Hospital, Boston, MA, United States
| | - Ye Han
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
| | - Andrew P. Robinson
- Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Northwestern University, Chicago, IL, United States
| | - Samuel E. Weinberg
- Department of Medicine, Northwestern University, Chicago, IL, United States
| | - Daniel W. Fisher
- Department of Psychiatry, University of Washington, Seattle, WA, United States
| | - Robert J. Heuermann
- Department of Neurology, Washington University, St. Louis, MO, United States
| | - Reagan E. Lyman
- Heritage College of Osteopathic Medicine, Ohio University, Dublin, OH, United States
| | - Dong Kyu Kim
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States
- Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Andreas Ludwig
- Institut fur Experimentelle und Klinische Pharmakologie und Toxikologie, Friedrich-Alexander-Universitat Erlangen-Nurnberg, Erlangen, Germany
| | - Navdeep S. Chandel
- Department of Medicine, Northwestern University, Chicago, IL, United States
| | - Mark D. Does
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, United States
- Vanderbilt University Institute of Imaging Science, Vanderbilt University, Nashville, TN, United States
- Department of Radiology and Radiological Sciences, Vanderbilt University School of Medicine, Nashville, TN, United States
- Department of Electrical Engineering, Vanderbilt University, Nashville, TN, United States
| | - Stephen D. Miller
- Department of Microbiology-Immunology and Interdepartmental Immunobiology Center, Northwestern University, Chicago, IL, United States
| | - Dane M. Chetkovich
- Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, United States
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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