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Roy D, Dion E, Sepeda JA, Peng J, Lingam SR, Townsend K, Sas A, Sun W, Tedeschi A. α2δ1-mediated maladaptive sensory plasticity disrupts adipose tissue homeostasis following spinal cord injury. Cell Rep Med 2024; 5:101525. [PMID: 38663398 PMCID: PMC11148638 DOI: 10.1016/j.xcrm.2024.101525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Revised: 01/13/2024] [Accepted: 04/02/2024] [Indexed: 05/23/2024]
Abstract
Spinal cord injury (SCI) increases the risk of cardiometabolic disorders, including hypertension, dyslipidemia, and insulin resistance. Not only does SCI lead to pathological expansion of adipose tissue, but it also leads to ectopic lipid accumulation in organs integral to glucose and insulin metabolism. The pathophysiological changes that underlie adipose tissue dysfunction after SCI are unknown. Here, we find that SCI exacerbates lipolysis in epididymal white adipose tissue (eWAT). Whereas expression of the α2δ1 subunit of voltage-gated calcium channels increases in calcitonin gene-related peptide-positive dorsal root ganglia neurons that project to eWAT, conditional deletion of the gene encoding α2δ1 in these neurons normalizes eWAT lipolysis after SCI. Furthermore, α2δ1 pharmacological blockade through systemic administration of gabapentin also normalizes eWAT lipolysis after SCI, preventing ectopic lipid accumulation in the liver. Thus, our study provides insight into molecular causes of maladaptive sensory processing in eWAT, facilitating the development of strategies to reduce metabolic and cardiovascular complications after SCI.
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Affiliation(s)
- Debasish Roy
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Elliot Dion
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Jesse A Sepeda
- Department of Neurology, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Juan Peng
- Center for Biostatistics and Bioinformatics, The Ohio State University, Columbus, OH 43210, USA
| | - Sai Rishik Lingam
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Kristy Townsend
- Department of Neurological Surgery, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Andrew Sas
- Department of Neurology, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Wenjing Sun
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA
| | - Andrea Tedeschi
- Department of Neuroscience, Wexner Medical Center, The Ohio State University, Columbus, OH 43210, USA; Chronic Brain Injury Program, The Ohio State University, Columbus, OH 43210, USA.
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2
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Jacobo-Piqueras N, Theiner T, Geisler SM, Tuluc P. Molecular mechanism responsible for sex differences in electrical activity of mouse pancreatic β cells. JCI Insight 2024; 9:e171609. [PMID: 38358819 PMCID: PMC11063940 DOI: 10.1172/jci.insight.171609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 02/08/2024] [Indexed: 02/17/2024] Open
Abstract
In humans, type 2 diabetes mellitus shows a higher prevalence in men compared with women, a phenotype that has been attributed to a lower peripheral insulin sensitivity in men. Whether sex-specific differences in pancreatic β cell function also contribute is largely unknown. Here, we characterized the electrophysiological properties of β cells in intact male and female mouse islets. Elevation of glucose concentration above 5 mM triggered an electrical activity with a similar glucose dependence in β cells of both sexes. However, female β cells had a more depolarized membrane potential and increased firing frequency compared with males. The higher membrane depolarization in female β cells was caused by approximately 50% smaller Kv2.1 K+ currents compared with males but otherwise unchanged KATP, large-conductance and small-conductance Ca2+-activated K+ channels, and background TASK1/TALK1 K+ current densities. In female β cells, the higher depolarization caused a membrane potential-dependent inactivation of the voltage-gated Ca2+ channels (CaV), resulting in reduced Ca2+ entry. Nevertheless, this reduced Ca2+ influx was offset by a higher action potential firing frequency. Because exocytosis of insulin granules does not show a sex-specific difference, we conclude that the higher electrical activity promotes insulin release in females, improving glucose tolerance.
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3
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Ortner NJ, Sah A, Paradiso E, Shin J, Stojanovic S, Hammer N, Haritonova M, Hofer NT, Marcantoni A, Guarina L, Tuluc P, Theiner T, Pitterl F, Ebner K, Oberacher H, Carbone E, Stefanova N, Ferraguti F, Singewald N, Roeper J, Striessnig J. The human channel gating-modifying A749G CACNA1D (Cav1.3) variant induces a neurodevelopmental syndrome-like phenotype in mice. JCI Insight 2023; 8:e162100. [PMID: 37698939 PMCID: PMC10619503 DOI: 10.1172/jci.insight.162100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 09/06/2023] [Indexed: 09/14/2023] Open
Abstract
Germline de novo missense variants of the CACNA1D gene, encoding the pore-forming α1 subunit of Cav1.3 L-type Ca2+ channels (LTCCs), have been found in patients with neurodevelopmental and endocrine dysfunction, but their disease-causing potential is unproven. These variants alter channel gating, enabling enhanced Cav1.3 activity, suggesting Cav1.3 inhibition as a potential therapeutic option. Here we provide proof of the disease-causing nature of such gating-modifying CACNA1D variants using mice (Cav1.3AG) containing the A749G variant reported de novo in a patient with autism spectrum disorder (ASD) and intellectual impairment. In heterozygous mutants, native LTCC currents in adrenal chromaffin cells exhibited gating changes as predicted from heterologous expression. The A749G mutation induced aberrant excitability of dorsomedial striatum-projecting substantia nigra dopamine neurons and medium spiny neurons in the dorsal striatum. The phenotype observed in heterozygous mutants reproduced many of the abnormalities described within the human disease spectrum, including developmental delay, social deficit, and pronounced hyperactivity without major changes in gross neuroanatomy. Despite an approximately 7-fold higher sensitivity of A749G-containing channels to the LTCC inhibitor isradipine, oral pretreatment over 2 days did not rescue the hyperlocomotion. Cav1.3AG mice confirm the pathogenicity of the A749G variant and point toward a pathogenetic role of altered signaling in the dopamine midbrain system.
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Affiliation(s)
- Nadine J. Ortner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Anupam Sah
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Enrica Paradiso
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Josef Shin
- Institute for Neurophysiology, Goethe University, Frankfurt, Germany
| | | | - Niklas Hammer
- Institute for Neurophysiology, Goethe University, Frankfurt, Germany
| | - Maria Haritonova
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Nadja T. Hofer
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Andrea Marcantoni
- Department of Drug Science, N.I.S. Centre, University of Torino, Torino, Italy
| | - Laura Guarina
- Department of Drug Science, N.I.S. Centre, University of Torino, Torino, Italy
| | - Petronel Tuluc
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Tamara Theiner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Florian Pitterl
- Institute of Legal Medicine and Core Facility Metabolomics and
| | - Karl Ebner
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | | | - Emilio Carbone
- Department of Drug Science, N.I.S. Centre, University of Torino, Torino, Italy
| | - Nadia Stefanova
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Francesco Ferraguti
- Department of Pharmacology, Medical University of Innsbruck, Innsbruck, Austria
| | - Nicolas Singewald
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
| | - Jochen Roeper
- Institute for Neurophysiology, Goethe University, Frankfurt, Germany
| | - Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
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4
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Seitter H, Obkircher J, Grabher P, Hartl J, Zanetti L, Lux UT, Fotakis G, Fernández-Quintero ML, Kaserer T, Koschak A. A novel calcium channel Cavβ 2 splice variant with unique properties predominates in the retina. J Biol Chem 2023; 299:102972. [PMID: 36738788 PMCID: PMC10074810 DOI: 10.1016/j.jbc.2023.102972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 01/15/2023] [Accepted: 01/17/2023] [Indexed: 02/05/2023] Open
Abstract
Cavβ subunits are essential for surface expression of voltage-gated calcium channel complexes and crucially modulate biophysical properties like voltage-dependent inactivation. Here, we describe the discovery and characterization of a novel Cavβ2 variant with distinct features that predominates in the retina. We determined spliced exons in retinal transcripts of the Cacnb2 gene, coding for Cavβ2, by RNA-Seq data analysis and quantitative PCR. We cloned a novel Cavβ2 splice variant from mouse retina, which we are calling β2i, and investigated biophysical properties of calcium currents with this variant in a heterologous expression system as well as its intrinsic membrane interaction when expressed alone. Our data showed that β2i predominated in the retina with expression in photoreceptors and bipolar cells. Furthermore, we observed that the β2i N-terminus exhibited an extraordinary concentration of hydrophobic residues, a distinct feature not seen in canonical variants. The biophysical properties resembled known membrane-associated variants, and β2i exhibited both a strong membrane association and a propensity for clustering, which depended on hydrophobic residues in its N-terminus. We considered available Cavβ structure data to elucidate potential mechanisms underlying the observed characteristics but resolved N-terminus structures were lacking and thus, precluded clear conclusions. With this description of a novel N-terminus variant of Cavβ2, we expand the scope of functional variation through N-terminal splicing with a distinct form of membrane attachment. Further investigation of the molecular mechanisms underlying the features of β2i could provide new angles on the way Cavβ subunits modulate Ca2+ channels at the plasma membrane.
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Affiliation(s)
- Hartwig Seitter
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria.
| | - Jana Obkircher
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Patricia Grabher
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Julia Hartl
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Lucia Zanetti
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Uwe Thorsten Lux
- Department of Biology, Animal Physiology/Neurobiology, Friedrich-Alexander-University Erlangen-Nürnberg, Erlangen, Germany
| | - Georgios Fotakis
- Institute of Bioinformatics, Medical University of Innsbruck, Innsbruck, Austria
| | | | - Teresa Kaserer
- Department of Pharmaceutical Chemistry, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria
| | - Alexandra Koschak
- Department of Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck, Innsbruck, Austria.
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5
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Hessenberger M, Haddad S, Obermair GJ. Pathophysiological Roles of Auxiliary Calcium Channel α 2δ Subunits. Handb Exp Pharmacol 2023; 279:289-316. [PMID: 36598609 DOI: 10.1007/164_2022_630] [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: 01/05/2023]
Abstract
α2δ proteins serve as auxiliary subunits of voltage-gated calcium channels, which are essential components of excitable cells such as skeletal and heart muscles, nerve cells of the brain and the peripheral nervous system, as well as endocrine cells. Over the recent years, α2δ proteins have been identified as critical regulators of synaptic functions, including the formation and differentiation of synapses. These functions require signalling mechanisms which are partly independent of calcium channels. Hence, in light of these features it is not surprising that the genes encoding for the four α2δ isoforms have recently been linked to neurological and neurodevelopmental disorders including epilepsy, autism spectrum disorders, schizophrenia, and depressive and bipolar disorders. Despite the increasing number of identified disease-associated mutations, the underlying pathophysiological mechanisms are only beginning to emerge. However, a thorough understanding of the pathophysiological role of α2δ proteins ideally serves two purposes: first, it will contribute to our understanding of general pathological mechanisms in synaptic disorders. Second, it may support the future development of novel and specific treatments for brain disorders. In this context, it is noteworthy that the antiepileptic and anti-allodynic drugs gabapentin and pregabalin both act via binding to α2δ proteins and are among the top sold drugs for treating neuropathic pain. In this book chapter, we will discuss recent developments in our understanding of the functions of α2δ proteins, both as calcium channel subunits and as independent regulatory entities. Furthermore, we present and summarize recently identified and likely pathogenic mutations in the genes encoding α2δ proteins and discuss potential underlying pathophysiological consequences at the molecular and structural level.
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Affiliation(s)
- Manuel Hessenberger
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria
| | - Sabrin Haddad
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria
- Institute of Physiology, Medical University of Innsbruck, Innsbruck, Austria
| | - Gerald J Obermair
- Division Physiology, Department Pharmacology, Physiology and Microbiology, Karl Landsteiner University of Health Sciences, Krems, Austria.
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6
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Yan X, Zhao Z, Weaver J, Sun T, Yun JW, Roneker CA, Hu F, Doliba NM, McCormick CCW, Vatamaniuk MZ, Lei XG. Role and mechanism of REG2 depletion in insulin secretion augmented by glutathione peroxidase-1 overproduction. Redox Biol 2022; 56:102457. [PMID: 36063729 PMCID: PMC9463454 DOI: 10.1016/j.redox.2022.102457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 08/15/2022] [Accepted: 08/24/2022] [Indexed: 11/23/2022] Open
Abstract
We previously reported a depletion of murine regenerating islet-derived protein 2 (REG2) in pancreatic islets of glutathione peroxidase-1 (Gpx1) overexpressing (OE) mice. The present study was to explore if and how the REG2 depletion contributed to an augmented glucose stimulated insulin secretion (GSIS) in OE islets. After we verified a consistent depletion (90%, p < 0.05) of REG2 mRNA, transcript, and protein in OE islets compared with wild-type (WT) controls, we treated cultured and perifused OE islets (70 islets/sample) with REG2 (1 μg/ml or ml · min) and observed 30-40% (p < 0.05) inhibitions of GSIS by REG2. Subsequently, we obtained evidences of co-immunoprecipitation, cell surface ligand binding, and co-immunofluorescence for a ligand-receptor binding between REG2 and transmembrane, L-type voltage-dependent Ca2+ channel (CaV1.2) in beta TC3 cells. Mutating the C-type lectin binding domain of REG2 or deglycosylating CaV1.2 removed the inhibition of REG2 on GSIS and(or) the putative binding between the two proteins. Treating cultured OE and perifused WT islets with REG2 (1 μg/ml or ml · min) decreased (p < 0.05) Ca2+ influx triggered by glucose or KCl. An intraperitoneal (ip) injection of REG2 (2 μg/g) to OE mice (6-month old, n = 10) decreased their plasma insulin concentration (46%, p < 0.05) and elevated their plasma glucose concentration (25%, p < 0.05) over a 60 min period after glucose challenge (ip, 1 g/kg). In conclusion, our study identifies REG2 as a novel regulator of Ca2+ influx and insulin secretion, and reveals a new cascade of GPX1/REG2/CaV1.2 to explain how REG2 depletion in OE islets could decrease its binding to CaV1.2, resulting in uninhibited Ca2+ influx and augmented GSIS. These findings create new links to bridge redox biology, tissue regeneration, and insulin secretion.
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Affiliation(s)
- Xi Yan
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA
| | - Zeping Zhao
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA
| | - Jeremy Weaver
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA
| | - Tao Sun
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA
| | - Jun-Won Yun
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA; Laboratory of Veterinary Toxicology, College of Veterinary Medicine, Seoul National University, Seoul, 08826, Republic of Korea
| | - Carol A Roneker
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA
| | - Fenghua Hu
- Department of Molecular Biology and Genetics, Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Nicolai M Doliba
- Institute of Diabetes, Obesity and Metabolism, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | | | - Marko Z Vatamaniuk
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA.
| | - Xin Gen Lei
- Department of Animal Science, Cornell University, Ithaca, NY, 14853, USA.
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7
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Becker A, Wardas B, Salah H, Amini M, Fecher-Trost C, Sen Q, Martus D, Beck A, Philipp SE, Flockerzi V, Belkacemi A. Cavβ3 Regulates Ca 2+ Signaling and Insulin Expression in Pancreatic β-Cells in a Cell-Autonomous Manner. Diabetes 2021; 70:2532-2544. [PMID: 34426509 PMCID: PMC8564405 DOI: 10.2337/db21-0078] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022]
Abstract
Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavβ subunits. In fibroblasts, Cavβ3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavβ3 could affect cytosolic calcium concentration ([Ca2 +]) in pancreatic β-cells. In this study, we deleted the Cavβ3-encoding gene Cacnb3 in insulin-secreting rat β-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavβ3 on Ca2+ signaling, glucose-induced insulin secretion (GIIS), Cav channel activity, and gene expression in wild-type cells in which Cavβ3 and the IP3 receptor were coimmunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, proprotein convertase subtilisin/kexin type-1, and nitric oxide synthase-1 in Cavβ3-knockout cells. In the absence of Cavβ3, Cav currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+ oscillations were increased. These processes were decreased by the Cavβ3 protein in a concentration-dependent manner. Our study shows that Cavβ3 interacts with the IP3 receptor in isolated β-cells, controls IP3-dependent Ca2+-signaling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.
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Affiliation(s)
- Alexander Becker
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Barbara Wardas
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Houssein Salah
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Maryam Amini
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Claudia Fecher-Trost
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Qiao Sen
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Damian Martus
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Andreas Beck
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Stephan E Philipp
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Veit Flockerzi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Anouar Belkacemi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
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8
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Li J, Zhou L, Ouyang X, He P. Transcription Factor-7-Like-2 (TCF7L2) in Atherosclerosis: A Potential Biomarker and Therapeutic Target. Front Cardiovasc Med 2021; 8:701279. [PMID: 34568447 PMCID: PMC8459927 DOI: 10.3389/fcvm.2021.701279] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/09/2021] [Indexed: 01/07/2023] Open
Abstract
Transcription factor-7-like-2 (TCF7L2), a vital member of the T-cell factor/lymphoid enhancer factor (TCF/LEF) family, plays an important role in normal human physiological and pathological processes. TCF7L2 exhibits multiple anti-atherosclerotic effects through the activation of specific molecular mechanisms, including regulation of metabolic homeostasis, macrophage polarization, and neointimal hyperplasia. A single-nucleotide substitution of TCF7L2, rs7903146, is a genetic high-risk factor for type 2 diabetes and indicates susceptibility to cardiovascular disease as a link between metabolic disorders and atherosclerosis. In this review, we summarize the anti-atherosclerosis effect and novel mechanisms underlying the function of TCF7L2 to elucidate its potential as an anti-atherosclerosis biomarker and provide a novel therapeutic target for cardiovascular diseases.
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Affiliation(s)
- Junyi Li
- School of Nursing, Hengyang Medical College, University of South China, Hengyang, China
| | - Li Zhou
- Department of Pathology, Chongqing Public Health Medical Center, Southwest University Public Health Hospital, Chongqing, China
| | - Xinping Ouyang
- Hengyang Key Laboratory of Neurodegeneration and Cognitive Impairment, Department of Physiology, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, Hengyang Medical College, The Neuroscience Institute, University of South China, Hengyang, China
| | - Pingping He
- School of Nursing, Hengyang Medical College, University of South China, Hengyang, China
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9
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Tuluc P, Theiner T, Jacobo-Piqueras N, Geisler SM. Role of High Voltage-Gated Ca 2+ Channel Subunits in Pancreatic β-Cell Insulin Release. From Structure to Function. Cells 2021; 10:2004. [PMID: 34440773 PMCID: PMC8393260 DOI: 10.3390/cells10082004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 02/07/2023] Open
Abstract
The pancreatic islets of Langerhans secrete several hormones critical for glucose homeostasis. The β-cells, the major cellular component of the pancreatic islets, secrete insulin, the only hormone capable of lowering the plasma glucose concentration. The counter-regulatory hormone glucagon is secreted by the α-cells while δ-cells secrete somatostatin that via paracrine mechanisms regulates the α- and β-cell activity. These three peptide hormones are packed into secretory granules that are released through exocytosis following a local increase in intracellular Ca2+ concentration. The high voltage-gated Ca2+ channels (HVCCs) occupy a central role in pancreatic hormone release both as a source of Ca2+ required for excitation-secretion coupling as well as a scaffold for the release machinery. HVCCs are multi-protein complexes composed of the main pore-forming transmembrane α1 and the auxiliary intracellular β, extracellular α2δ, and transmembrane γ subunits. Here, we review the current understanding regarding the role of all HVCC subunits expressed in pancreatic β-cell on electrical activity, excitation-secretion coupling, and β-cell mass. The evidence we review was obtained from many seminal studies employing pharmacological approaches as well as genetically modified mouse models. The significance for diabetes in humans is discussed in the context of genetic variations in the genes encoding for the HVCC subunits.
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Affiliation(s)
- Petronel Tuluc
- Centre for Molecular Biosciences, Department of Pharmacology and Toxicology, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; (T.T.); (N.J.-P.); (S.M.G.)
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10
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Zakaria A, Berthault C, Cosson B, Jung V, Guerrera IC, Rachdi L, Scharfmann R. Glucose treatment of human pancreatic β-cells enhances translation of mRNAs involved in energetics and insulin secretion. J Biol Chem 2021; 297:100839. [PMID: 34051232 PMCID: PMC8253965 DOI: 10.1016/j.jbc.2021.100839] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 05/17/2021] [Accepted: 05/25/2021] [Indexed: 12/30/2022] Open
Abstract
Glucose-mediated signaling regulates the expression of a limited number of genes in human pancreatic β-cells at the transcriptional level. However, it is unclear whether glucose plays a role in posttranscriptional RNA processing or translational control of gene expression. Here, we asked whether glucose affects posttranscriptional steps and regulates protein synthesis in human β-cell lines. We first showed the involvement of the mTOR pathway in glucose-related signaling. We also used the surface sensing of translation technique, based on puromycin incorporation into newly translated proteins, to demonstrate that glucose treatment increased protein translation. Among the list of glucose-induced proteins, we identified the proconvertase PCSK1, an enzyme involved in the proteolytic conversion of proinsulin to insulin, whose translation was induced within minutes following glucose treatment. We finally performed global proteomic analysis by mass spectrometry to characterize newly translated proteins upon glucose treatment. We found enrichment in proteins involved in translation, glycolysis, TCA metabolism, and insulin secretion. Taken together, our study demonstrates that, although glucose minorly affects gene transcription in human β-cells, it plays a major role at the translational level.
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Affiliation(s)
- Albatoul Zakaria
- Institut Cochin, INSERM U1016, CNRS UMR 8104, Université de Paris, Paris, France
| | - Claire Berthault
- Institut Cochin, INSERM U1016, CNRS UMR 8104, Université de Paris, Paris, France
| | - Bertrand Cosson
- Epigenetics and Cell Fate Center, CNRS UMR 7216, Université de Paris, Paris, France
| | - Vincent Jung
- Plateforme protéomique Necker, INSERM US24/CNRS UMS3633, Université de Paris, Structure Fédérative de Recherche Necker, Paris, France
| | - Ida Chiara Guerrera
- Plateforme protéomique Necker, INSERM US24/CNRS UMS3633, Université de Paris, Structure Fédérative de Recherche Necker, Paris, France
| | - Latif Rachdi
- Institut Cochin, INSERM U1016, CNRS UMR 8104, Université de Paris, Paris, France.
| | - Raphael Scharfmann
- Institut Cochin, INSERM U1016, CNRS UMR 8104, Université de Paris, Paris, France.
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11
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Striessnig J. Voltage-Gated Ca 2+-Channel α1-Subunit de novo Missense Mutations: Gain or Loss of Function - Implications for Potential Therapies. Front Synaptic Neurosci 2021; 13:634760. [PMID: 33746731 PMCID: PMC7966529 DOI: 10.3389/fnsyn.2021.634760] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Accepted: 02/02/2021] [Indexed: 12/12/2022] Open
Abstract
This review summarizes our current knowledge of human disease-relevant genetic variants within the family of voltage gated Ca2+ channels. Ca2+ channelopathies cover a wide spectrum of diseases including epilepsies, autism spectrum disorders, intellectual disabilities, developmental delay, cerebellar ataxias and degeneration, severe cardiac arrhythmias, sudden cardiac death, eye disease and endocrine disorders such as congential hyperinsulinism and hyperaldosteronism. A special focus will be on the rapidly increasing number of de novo missense mutations identified in the pore-forming α1-subunits with next generation sequencing studies of well-defined patient cohorts. In contrast to likely gene disrupting mutations these can not only cause a channel loss-of-function but can also induce typical functional changes permitting enhanced channel activity and Ca2+ signaling. Such gain-of-function mutations could represent therapeutic targets for mutation-specific therapy of Ca2+-channelopathies with existing or novel Ca2+-channel inhibitors. Moreover, many pathogenic mutations affect positive charges in the voltage sensors with the potential to form gating-pore currents through voltage sensors. If confirmed in functional studies, specific blockers of gating-pore currents could also be of therapeutic interest.
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Affiliation(s)
- Jörg Striessnig
- Department of Pharmacology and Toxicology, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innsbruck, Austria
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12
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Geisler SM, Benedetti A, Schöpf CL, Schwarzer C, Stefanova N, Schwartz A, Obermair GJ. Phenotypic Characterization and Brain Structure Analysis of Calcium Channel Subunit α 2δ-2 Mutant (Ducky) and α 2δ Double Knockout Mice. Front Synaptic Neurosci 2021; 13:634412. [PMID: 33679366 PMCID: PMC7933509 DOI: 10.3389/fnsyn.2021.634412] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Accepted: 01/11/2021] [Indexed: 01/19/2023] Open
Abstract
Auxiliary α2δ subunits of voltage-gated calcium channels modulate channel trafficking, current properties, and synapse formation. Three of the four isoforms (α2δ-1, α2δ-2, and α2δ-3) are abundantly expressed in the brain; however, of the available knockout models, only α2δ-2 knockout or mutant mice display an obvious abnormal neurological phenotype. Thus, we hypothesize that the neuronal α2δ isoforms may have partially specific as well as redundant functions. To address this, we generated three distinct α2δ double knockout mouse models by crossbreeding single knockout (α2δ-1 and -3) or mutant (α2δ-2/ducky) mice. Here, we provide a first phenotypic description and brain structure analysis. We found that genotypic distribution of neonatal litters in distinct α2δ-1/-2, α2δ-1/-3, and α2δ-2/-3 breeding combinations did not conform to Mendel's law, suggesting premature lethality of single and double knockout mice. Notably, high occurrences of infant mortality correlated with the absence of specific α2δ isoforms (α2Δ-2 > α2δ-1 > α2δ-3), and was particularly observed in cages with behaviorally abnormal parenting animals of α2δ-2/-3 cross-breedings. Juvenile α2δ-1/-2 and α2δ-2/-3 double knockout mice displayed a waddling gate similar to ducky mice. However, in contrast to ducky and α2δ-1/-3 double knockout animals, α2δ-1/-2 and α2δ-2/-3 double knockout mice showed a more severe disease progression and highly impaired development. The observed phenotypes within the individual mouse lines may be linked to differences in the volume of specific brain regions. Reduced cortical volume in ducky mice, for example, was associated with a progressively decreased space between neurons, suggesting a reduction of total synaptic connections. Taken together, our findings show that α2δ subunits differentially regulate premature survival, postnatal growth, brain development, and behavior, suggesting specific neuronal functions in health and disease.
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Affiliation(s)
- Stefanie M. Geisler
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Department of Pharmacology and Toxicology, Center for Molecular Biosciences, University of Innsbruck, Innsbruck, Austria
| | - Ariane Benedetti
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Clemens L. Schöpf
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
| | - Christoph Schwarzer
- Department of Pharmacology, Medical University Innsbruck, Innsbruck, Austria
| | - Nadia Stefanova
- Division of Neurobiology, Department of Neurology, Medical University Innsbruck, Innsbruck, Austria
| | - Arnold Schwartz
- Department of Pharmacology and Systems Physiology, College of Medicine, University of Cincinnati, Cincinnati, OH, United States
| | - Gerald J. Obermair
- Institute of Physiology, Medical University Innsbruck, Innsbruck, Austria
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems an der Donau, Austria
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13
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Dickerson MT, Dadi PK, Butterworth RB, Nakhe AY, Graff SM, Zaborska KE, Schaub CM, Jacobson DA. Tetraspanin-7 regulation of L-type voltage-dependent calcium channels controls pancreatic β-cell insulin secretion. J Physiol 2020; 598:4887-4905. [PMID: 32790176 PMCID: PMC8095317 DOI: 10.1113/jp279941] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/20/2020] [Indexed: 12/20/2022] Open
Abstract
KEY POINTS Tetraspanin (TSPAN) proteins regulate many biological processes, including intracellular calcium (Ca2+ ) handling. TSPAN-7 is enriched in pancreatic islet cells; however, the function of islet TSPAN-7 has not been identified. Here, we characterize how β-cell TSPAN-7 regulates Ca2+ handling and hormone secretion. We find that TSPAN-7 reduces β-cell glucose-stimulated Ca2+ entry, slows Ca2+ oscillation frequency and decreases glucose-stimulated insulin secretion. TSPAN-7 controls β-cell function through a direct interaction with L-type voltage-dependent Ca2+ channels (CaV 1.2 and CaV 1.3), which reduces channel Ca2+ conductance. TSPAN-7 slows activation of CaV 1.2 and accelerates recovery from voltage-dependent inactivation; TSPAN-7 also slows CaV 1.3 inactivation kinetics. These findings strongly implicate TSPAN-7 as a key regulator in determining the set-point of glucose-stimulated Ca2+ influx and insulin secretion. ABSTRACT Glucose-stimulated insulin secretion (GSIS) is regulated by calcium (Ca2+ ) entry into pancreatic β-cells through voltage-dependent Ca2+ (CaV ) channels. Tetraspanin (TSPAN) transmembrane proteins control Ca2+ handling, and thus they may also modulate GSIS. TSPAN-7 is the most abundant islet TSPAN and immunostaining of mouse and human pancreatic slices shows that TSPAN-7 is highly expressed in β- and α-cells; however, the function of islet TSPAN-7 has not been determined. Here, we show that TSPAN-7 knockdown (KD) increases glucose-stimulated Ca2+ influx into mouse and human β-cells. Additionally, mouse β-cell Ca2+ oscillation frequency was accelerated by TSPAN-7 KD. Because TSPAN-7 KD also enhanced Ca2+ entry when membrane potential was clamped with depolarization, the effect of TSPAN-7 on CaV channel activity was examined. TSPAN-7 KD enhanced L-type CaV currents in mouse and human β-cells. Conversely, heterologous expression of TSPAN-7 with CaV 1.2 and CaV 1.3 L-type CaV channels decreased CaV currents and reduced Ca2+ influx through both channels. This was presumably the result of a direct interaction of TSPAN-7 and L-type CaV channels because TSPAN-7 coimmunoprecipitated with both CaV 1.2 and CaV 1.3 from primary human β-cells and from a heterologous expression system. Finally, TSPAN-7 KD in human β-cells increased basal (5.6 mM glucose) and stimulated (45 mM KCl + 14 mM glucose) insulin secretion. These findings strongly suggest that TSPAN-7 modulation of β-cell L-type CaV channels is a key determinant of β-cell glucose-stimulated Ca2+ entry and thus the set-point of GSIS.
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Affiliation(s)
- Matthew T Dickerson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Prasanna K Dadi
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Regan B Butterworth
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Arya Y Nakhe
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Sarah M Graff
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Karolina E Zaborska
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - Charles M Schaub
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
| | - David A Jacobson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, 7425B MRB IV, Nashville, TN, USA
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14
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Bikbaev A, Ciuraszkiewicz-Wojciech A, Heck J, Klatt O, Freund R, Mitlöhner J, Enrile Lacalle S, Sun M, Repetto D, Frischknecht R, Ablinger C, Rohlmann A, Missler M, Obermair GJ, Di Biase V, Heine M. Auxiliary α2δ1 and α2δ3 Subunits of Calcium Channels Drive Excitatory and Inhibitory Neuronal Network Development. J Neurosci 2020; 40:4824-4841. [PMID: 32414783 PMCID: PMC7326358 DOI: 10.1523/jneurosci.1707-19.2020] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 03/31/2020] [Accepted: 05/09/2020] [Indexed: 01/21/2023] Open
Abstract
VGCCs are multisubunit complexes that play a crucial role in neuronal signaling. Auxiliary α2δ subunits of VGCCs modulate trafficking and biophysical properties of the pore-forming α1 subunit and trigger excitatory synaptogenesis. Alterations in the expression level of α2δ subunits were implicated in several syndromes and diseases, including chronic neuropathic pain, autism, and epilepsy. However, the contribution of distinct α2δ subunits to excitatory/inhibitory imbalance and aberrant network connectivity characteristic for these pathologic conditions remains unclear. Here, we show that α2δ1 overexpression enhances spontaneous neuronal network activity in developing and mature cultures of hippocampal neurons. In contrast, overexpression, but not downregulation, of α2δ3 enhances neuronal firing in immature cultures, whereas later in development it suppresses neuronal activity. We found that α2δ1 overexpression increases excitatory synaptic density and selectively enhances presynaptic glutamate release, which is impaired on α2δ1 knockdown. Overexpression of α2δ3 increases the excitatory synaptic density as well but also facilitates spontaneous GABA release and triggers an increase in the density of inhibitory synapses, which is accompanied by enhanced axonaloutgrowth in immature interneurons. Together, our findings demonstrate that α2δ1 and α2δ3 subunits play distinct but complementary roles in driving formation of structural and functional network connectivity during early development. An alteration in α2δ surface expression during critical developmental windows can therefore play a causal role and have a profound impact on the excitatory-to-inhibitory balance and network connectivity.SIGNIFICANCE STATEMENT The computational capacity of neuronal networks is determined by their connectivity. Chemical synapses are the main interface for transfer of information between individual neurons. The initial formation of network connectivity requires spontaneous electrical activity and the calcium channel-mediated signaling. We found that, in early development, auxiliary α2δ3 subunits of calcium channels foster presynaptic release of GABA, trigger formation of inhibitory synapses, and promote axonal outgrowth in inhibitory interneurons. In contrast, later in development, α2δ1 subunits promote the glutamatergic neurotransmission and synaptogenesis, as well as strongly enhance neuronal network activity. We propose that formation of connectivity in neuronal networks is associated with a concerted interplay of α2δ1 and α2δ3 subunits of calcium channels.
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Affiliation(s)
- Arthur Bikbaev
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
| | - Anna Ciuraszkiewicz-Wojciech
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
- Center for Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, 39106, Germany
| | - Jennifer Heck
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
| | - Oliver Klatt
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Romy Freund
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Jessica Mitlöhner
- RG Brain Extracellular Matrix, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Sara Enrile Lacalle
- RG Molecular Physiology, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
| | - Miao Sun
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Daniele Repetto
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Renato Frischknecht
- RG Brain Extracellular Matrix, Leibniz Institute for Neurobiology, Magdeburg, 39118, Germany
- Department of Biology, Animal Physiology, Friedrich Alexander University of Erlangen-Nuremberg, Erlangen, 91058, Germany
| | - Cornelia Ablinger
- Institute of Physiology, Medical University Innsbruck, Innsbruck, 6020, Austria
| | - Astrid Rohlmann
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Markus Missler
- Institute for Anatomy and Molecular Neurobiology, University of Münster, Münster, 48149, Germany
| | - Gerald J Obermair
- Division Physiology, Karl Landsteiner University of Health Sciences, Krems, 3500, Austria
| | - Valentina Di Biase
- Institute of Molecular and Clinical Pharmacology, Medical University Innsbruck, Innsbruck, 6020, Austria
| | - Martin Heine
- RG Functional Neurobiology, Institute for Developmental Biology and Neurobiology, Johannes Gutenberg University Mainz, Mainz, 55128, Germany
- Center for Behavioral Brain Sciences, Otto-von-Guericke University Magdeburg, Magdeburg, 39106, Germany
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15
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Ye Y, Barghouth M, Luan C, Kazim A, Zhou Y, Eliasson L, Zhang E, Hansson O, Thevenin T, Renström E. The TCF7L2-dependent high-voltage activated calcium channel subunit α2δ-1 controls calcium signaling in rodent pancreatic beta-cells. Mol Cell Endocrinol 2020; 502:110673. [PMID: 31805307 DOI: 10.1016/j.mce.2019.110673] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 11/19/2019] [Accepted: 11/30/2019] [Indexed: 12/16/2022]
Abstract
The transcription factor TCF7L2 remains the most important diabetes gene identified to date and genetic risk carriers exhibit lower insulin secretion. We show that Tcf7l2 regulates the auxiliary subunit of voltage-gated Ca2+ channels, Cacna2d1 gene/α2δ-1 protein levels. Furthermore, suppression of α2δ-1 decreased voltage-gated Ca2+ currents and high glucose/depolarization-evoked Ca2+ signaling which mimicked the effect of silencing of Tcf7l2. This appears to be the result of impaired voltage-gated Ca2+ channel trafficking to the plasma membrane, as Cav1.2 channels accumulated in the recycling endosomes after α2δ-1 suppression, in clonal as well as primary rodent beta-cells. This impaired the capacity for glucose-induced insulin secretion in Cacna2d1-silenced cells. Overexpression of α2δ-1 increased high-glucose/K+-stimulated insulin secretion. Furthermore, overexpression of α2δ-1 in Tcf7l2-silenced cells rescued the Tcf7l2-dependent impairment of Ca2+ signaling, but not the reduced insulin secretion. Taken together, these data clarify the connection between Tcf7l2, α2δ-1 in Ca2+-dependent insulin secretion.
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Affiliation(s)
- Yingying Ye
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Mohammad Barghouth
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Cheng Luan
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Abdulla Kazim
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Yuedan Zhou
- Lund University, Department of Clinical Sciences, Diabetes and Endocrinology Group, Sweden
| | - Lena Eliasson
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Enming Zhang
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Ola Hansson
- Lund University, Department of Clinical Sciences, Diabetes and Endocrinology Group, Sweden
| | - Thomas Thevenin
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden
| | - Erik Renström
- Lund University, Department of Clinical Sciences, Islet Pathophysiology Group, Sweden.
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16
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IgGs from patients with amyotrophic lateral sclerosis and diabetes target Ca Vα 2δ1 subunits impairing islet cell function and survival. Proc Natl Acad Sci U S A 2019; 116:26816-26822. [PMID: 31826954 PMCID: PMC6936400 DOI: 10.1073/pnas.1911956116] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We provide evidence of a mechanistic link between ALS and T2DM. Our data show that a subgroup of ALS-T2DM patients have sera that enhance CaV1 channel-mediated Ca2+ influx and exaggerate [Ca2+]i. These effects occur because the sera accommodate cytotoxic IgG autoantibodies that immunocapture CaVα2δ1 subunits. As a consequence, impairments in [Ca2+]i dynamics, mitochondrial function, insulin secretion, and cell viability appear. We could clarify not only the identity of this serum factor but also the molecular mechanisms underlying its effects on the islet cells. Our findings may lay the foundation for a treatment strategy for this complex and severe group of diabetic patients. Patients with amyotrophic lateral sclerosis (ALS) often show hallmarks of type 2 diabetes mellitus (T2DM). However, the causal link between ALS and T2DM has remained a mystery. We now demonstrate that 60% of ALS patients with T2DM (ALS-T2DM) have sera that exaggerated K+-induced increases in cytosolic free Ca2+ concentration ([Ca2+]i) in mouse islet cells. The effect was attributed to the presence of pathogenic immunoglobulin Gs (IgGs) in ALS-T2DM sera. The pathogenic IgGs immunocaptured the voltage-dependent Ca2+ (CaV) channel subunit CaVα2δ1 in the plasma membrane enhancing CaV1 channel-mediated Ca2+ influx and [Ca2+]i, resulting in impaired mitochondrial function. Consequently, impairments in [Ca2+]i dynamics, insulin secretion, and cell viability occurred. These data reveal that patients with ALS-T2DM carry cytotoxic ALS-T2DM-IgG autoantibodies that serve as a causal link between ALS and T2DM by immunoattacking CaVα2δ1 subunits. Our findings may lay the foundation for a pharmacological treatment strategy for patients suffering from a combination of these diseases.
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17
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Geisler S, Schöpf CL, Stanika R, Kalb M, Campiglio M, Repetto D, Traxler L, Missler M, Obermair GJ. Presynaptic α 2δ-2 Calcium Channel Subunits Regulate Postsynaptic GABA A Receptor Abundance and Axonal Wiring. J Neurosci 2019; 39:2581-2605. [PMID: 30683685 PMCID: PMC6445987 DOI: 10.1523/jneurosci.2234-18.2019] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 01/03/2019] [Accepted: 01/08/2019] [Indexed: 01/26/2023] Open
Abstract
Presynaptic α2δ subunits of voltage-gated calcium channels regulate channel abundance and are involved in glutamatergic synapse formation. However, little is known about the specific functions of the individual α2δ isoforms and their role in GABAergic synapses. Using primary neuronal cultures of embryonic mice of both sexes, we here report that presynaptic overexpression of α2δ-2 in GABAergic synapses strongly increases clustering of postsynaptic GABAARs. Strikingly, presynaptic α2δ-2 exerts the same effect in glutamatergic synapses, leading to a mismatched localization of GABAARs. This mismatching is caused by an aberrant wiring of glutamatergic presynaptic boutons with GABAergic postsynaptic positions. The trans-synaptic effect of α2δ-2 is independent of the prototypical cell-adhesion molecules α-neurexins (α-Nrxns); however, α-Nrxns together with α2δ-2 can modulate postsynaptic GABAAR abundance. Finally, exclusion of the alternatively spliced exon 23 of α2δ-2 is essential for the trans-synaptic mechanism. The novel function of α2δ-2 identified here may explain how abnormal α2δ subunit expression can cause excitatory-inhibitory imbalance often associated with neuropsychiatric disorders.SIGNIFICANCE STATEMENT Voltage-gated calcium channels regulate important neuronal functions such as synaptic transmission. α2δ subunits modulate calcium channels and are emerging as regulators of brain connectivity. However, little is known about how individual α2δ subunits contribute to synapse specificity. Here, we show that presynaptic expression of a single α2δ variant can modulate synaptic connectivity and the localization of inhibitory postsynaptic receptors. Our findings provide basic insights into the development of specific synaptic connections between nerve cells and contribute to our understanding of normal nerve cell functions. Furthermore, the identified mechanism may explain how an altered expression of calcium channel subunits can result in aberrant neuronal wiring often associated with neuropsychiatric disorders such as autism or schizophrenia.
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Affiliation(s)
- Stefanie Geisler
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Clemens L Schöpf
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Ruslan Stanika
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Marcus Kalb
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Marta Campiglio
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Daniele Repetto
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Larissa Traxler
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
| | - Markus Missler
- Institute of Anatomy and Molecular Neurobiology, Westfälische Wilhelms-University, 48149 Münster, Germany
| | - Gerald J Obermair
- Division of Physiology, Medical University Innsbruck, 6020 Innsbruck, Austria, and
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18
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Bastidas-Ponce A, Tritschler S, Dony L, Scheibner K, Tarquis-Medina M, Salinno C, Schirge S, Burtscher I, Böttcher A, Theis F, Lickert H, Bakhti M. Massive single-cell mRNA profiling reveals a detailed roadmap for pancreatic endocrinogenesis. Development 2019; 146:dev.173849. [DOI: 10.1242/dev.173849] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 05/21/2019] [Indexed: 12/21/2022]
Abstract
Deciphering mechanisms of endocrine cell induction, specification and lineage allocation in vivo will provide valuable insights into how the islets of Langerhans are generated. Currently, it is ill defined how endocrine progenitors segregate into different endocrine subtypes during development. Here, we generated a novel Neurogenin3 (Ngn3)-Venus fusion (NVF) reporter mouse line, that closely mirrors the transient endogenous Ngn3 protein expression. To define an in vivo roadmap of endocrinogenesis, we performed single-cell RNA-sequencing of 36,351 pancreatic epithelial and NVF+ cells during secondary transition. This allowed to time-resolve and distinguish Ngn3low endocrine progenitors, Ngn3high endocrine precursors, Fev+ endocrine lineage and hormone+ endocrine subtypes and delineate molecular programs during the stepwise lineage restriction steps. Strikingly, we identified 58 novel signature genes that show the same transient expression dynamics as Ngn3 in the 7,260 profiled Ngn3-expressing cells. The differential expression of these genes in endocrine precursors associated with their cell-fate allocation towards distinct endocrine cell types. Thus, the generation of an accurately regulated NVF reporter allowed us to temporally resolve endocrine lineage development to provide a fine-grained single-cell molecular profile of endocrinogenesis in vivo.
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Affiliation(s)
- Aimée Bastidas-Ponce
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Medicine, Munich, Germany
| | - Sophie Tritschler
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Life Sciences Weihenstephan, Freising, Germany
| | - Leander Dony
- Institute of Computational Biology, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Max Planck Institute of Psychiatry, Kraepelinstr. 2-10, 80804 Munich, Germany
| | - Katharina Scheibner
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Medicine, Munich, Germany
| | - Marta Tarquis-Medina
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Medicine, Munich, Germany
| | - Ciro Salinno
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Medicine, Munich, Germany
| | - Silvia Schirge
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
| | - Ingo Burtscher
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
| | - Anika Böttcher
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
| | - Fabian Theis
- Institute of Computational Biology, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, Department of Mathematics, Munich, Germany
| | - Heiko Lickert
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- Technical University of Munich, School of Medicine, Munich, Germany
| | - Mostafa Bakhti
- Institute of Diabetes and Regeneration Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
- German Center for Diabetes Research (DZD), D-85764 Neuherberg, Germany
- Institute of Stem Cell Research, Helmholtz Zentrum München, D-85764 Neuherberg, Germany
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19
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Getting a handle on Ca V2.2 (N-type) voltage-gated Ca 2+ channels. Proc Natl Acad Sci U S A 2018; 115:12848-12850. [PMID: 30538200 DOI: 10.1073/pnas.1818608115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Ablation of α 2δ-1 inhibits cell-surface trafficking of endogenous N-type calcium channels in the pain pathway in vivo. Proc Natl Acad Sci U S A 2018; 115:E12043-E12052. [PMID: 30487217 PMCID: PMC6305000 DOI: 10.1073/pnas.1811212115] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Neuronal N-type (CaV2.2) voltage-gated calcium channels are important at the first synapse in the pain pathway. In this study, we have characterized a knockin mouse containing CaV2.2 with an extracellular HA tag to determine the localization of CaV2.2 in primary afferent pain pathways. These endogenous channels have been visualized at the plasma membrane and rigorously quantified in vivo. We examined the effect of ablation of the calcium channel auxiliary subunit α2δ-1 (the target of gabapentinoids) on CaV2.2 distribution. We found preferential cell-surface localization of CaV2.2 in DRG nociceptor neuron cell bodies was lost, accompanied by a dramatic reduction at dorsal horn terminals, but no effect on distribution of other spinal cord synaptic markers. The auxiliary α2δ calcium channel subunits play key roles in voltage-gated calcium channel function. Independent of this, α2δ-1 has also been suggested to be important for synaptogenesis. Using an epitope-tagged knockin mouse strategy, we examined the effect of α2δ-1 on CaV2.2 localization in the pain pathway in vivo, where CaV2.2 is important for nociceptive transmission and α2δ-1 plays a critical role in neuropathic pain. We find CaV2.2 is preferentially expressed on the plasma membrane of calcitonin gene-related peptide-positive small nociceptors. This is paralleled by strong presynaptic expression of CaV2.2 in the superficial spinal cord dorsal horn. EM-immunogold localization shows CaV2.2 predominantly in active zones of glomerular primary afferent terminals. Genetic ablation of α2δ-1 abolishes CaV2.2 cell-surface expression in dorsal root ganglion neurons and dramatically reduces dorsal horn expression. There was no effect of α2δ-1 knockout on other dorsal horn pre- and postsynaptic markers, indicating the primary afferent pathways are not otherwise affected by α2δ-1 ablation.
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Abstract
Voltage-gated calcium (CaV) channels are associated with β and α2δ auxiliary subunits. This review will concentrate on the function of the α2δ protein family, which has four members. The canonical role for α2δ subunits is to convey a variety of properties on the CaV1 and CaV2 channels, increasing the density of these channels in the plasma membrane and also enhancing their function. More recently, a diverse spectrum of non-canonical interactions for α2δ proteins has been proposed, some of which involve competition with calcium channels for α2δ or increase α2δ trafficking and others which mediate roles completely unrelated to their calcium channel function. The novel roles for α2δ proteins which will be discussed here include association with low-density lipoprotein receptor-related protein 1 (LRP1), thrombospondins, α-neurexins, prion proteins, large conductance (big) potassium (BK) channels, and N-methyl-d-aspartate (NMDA) receptors.
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Affiliation(s)
- Annette C Dolphin
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, WC1E 6BT, UK
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22
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Rorsman P, Ashcroft FM. Pancreatic β-Cell Electrical Activity and Insulin Secretion: Of Mice and Men. Physiol Rev 2018; 98:117-214. [PMID: 29212789 PMCID: PMC5866358 DOI: 10.1152/physrev.00008.2017] [Citation(s) in RCA: 433] [Impact Index Per Article: 72.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 05/30/2017] [Accepted: 06/18/2017] [Indexed: 12/14/2022] Open
Abstract
The pancreatic β-cell plays a key role in glucose homeostasis by secreting insulin, the only hormone capable of lowering the blood glucose concentration. Impaired insulin secretion results in the chronic hyperglycemia that characterizes type 2 diabetes (T2DM), which currently afflicts >450 million people worldwide. The healthy β-cell acts as a glucose sensor matching its output to the circulating glucose concentration. It does so via metabolically induced changes in electrical activity, which culminate in an increase in the cytoplasmic Ca2+ concentration and initiation of Ca2+-dependent exocytosis of insulin-containing secretory granules. Here, we review recent advances in our understanding of the β-cell transcriptome, electrical activity, and insulin exocytosis. We highlight salient differences between mouse and human β-cells, provide models of how the different ion channels contribute to their electrical activity and insulin secretion, and conclude by discussing how these processes become perturbed in T2DM.
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Affiliation(s)
- Patrik Rorsman
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Frances M Ashcroft
- Oxford Centre for Diabetes, Endocrinology and Metabolism, University of Oxford, Churchill Hospital, Oxford, United Kingdom; Department of Neuroscience and Physiology, Metabolic Research Unit, Göteborg, Sweden; and Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
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Lau LA, Noubary F, Wang D, Dulla CG. α2δ-1 Signaling Drives Cell Death, Synaptogenesis, Circuit Reorganization, and Gabapentin-Mediated Neuroprotection in a Model of Insult-Induced Cortical Malformation. eNeuro 2017; 4:ENEURO.0316-17.2017. [PMID: 29109971 PMCID: PMC5672548 DOI: 10.1523/eneuro.0316-17.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Revised: 10/10/2017] [Accepted: 10/13/2017] [Indexed: 01/08/2023] Open
Abstract
Developmental cortical malformations (DCMs) result from pre- and perinatal insults, as well as genetic mutations. Hypoxia, viral infection, and traumatic injury are the most common environmental causes of DCMs, and are associated with the subsyndromes focal polymicrogyria and focal cortical dysplasia (FCD) Type IIId, both of which have a high incidence of epilepsy. Understanding the molecular signals that lead to the formation of a hyperexcitable network in DCMs is critical to devising novel treatment strategies. In a previous study using the freeze-lesion (FL) murine model of DCM, we found that levels of thrombospondin (TSP) and the calcium channel auxiliary subunit α2δ-1 were elevated. TSP binds to α2δ-1 to drive the formation of excitatory synapses during development, suggesting that overactivation of this pathway may lead to exuberant excitatory synaptogenesis and network hyperexcitability seen in DCMs. In that study, antagonizing TSP/α2δ-1 signaling using the drug gabapentin (GBP) reduced many FL-induced pathologies. Here, we used mice with a genetic deletion of α2δ-1 to determine how α2δ-1 contributes to cell death, elevated excitatory synapse number, and in vitro network function after FL and to examine the molecular specificity of GBP's effects. We identified a critical role for α2δ-1 in FL-induced pathologies and in mediating the neuroprotective effects of GBP. Interestingly, genetic deletion of α2δ-1 did not eliminate GBP's effects on synaptogenesis, suggesting that GBP can have α2δ-1-independent effects. Taken together these studies suggests that inhibiting α2δ-1 signaling may have therapeutic promise to reduce cell death and network reorganization associated with insult-induced DCMs.
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Affiliation(s)
- Lauren A. Lau
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111
- Neuroscience Program, Tufts Sackler School of Biomedical Sciences, Boston, MA 02111
| | - Farzad Noubary
- The Institute for Clinical Research and Health Policy Studies, Tufts Medical Center, Boston, MA 02111
- Tufts Clinical and Translational Science Institute, Tufts University, Boston, MA 02111
| | - Dongqing Wang
- Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Chris G. Dulla
- Department of Neuroscience, Tufts University School of Medicine, Boston, MA 02111
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