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Lee JH, Park S, Perez-Flores MC, Chen Y, Kang M, Choi J, Levine L, Gratton MA, Zhao J, Notterpek L, Yamoah EN. Demyelination and Na + Channel Redistribution Underlie Auditory and Vestibular Dysfunction in PMP22-Null Mice. eNeuro 2024; 11:ENEURO.0462-23.2023. [PMID: 38378628 PMCID: PMC11059428 DOI: 10.1523/eneuro.0462-23.2023] [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: 11/05/2023] [Revised: 12/14/2023] [Accepted: 12/15/2023] [Indexed: 02/22/2024] Open
Abstract
Altered expression of peripheral myelin protein 22 (PMP22) results in demyelinating peripheral neuropathy. PMP22 exhibits a highly restricted tissue distribution with marked expression in the myelinating Schwann cells of peripheral nerves. Auditory and vestibular Schwann cells and the afferent neurons also express PMP22, suggesting a unique role in hearing and balancing. Indeed, neuropathic patients diagnosed with PMP22-linked hereditary neuropathies often present with auditory and balance deficits, an understudied clinical complication. To investigate the mechanism by which abnormal expression of PMP22 may cause auditory and vestibular deficits, we studied gene-targeted PMP22-null mice. PMP22-null mice exhibit an unsteady gait, have difficulty maintaining balance, and live for only ∼3-5 weeks relative to unaffected littermates. Histological analysis of the inner ear revealed reduced auditory and vestibular afferent nerve myelination and profound Na+ channel redistribution without PMP22. Yet, Na+ current density was unaltered, in stark contrast to increased K+ current density. Atypical postsynaptic densities and a range of neuronal abnormalities in the organ of Corti were also identified. Analyses of auditory brainstem responses (ABRs) and vestibular sensory-evoked potential (VsEP) revealed that PMP22-null mice had auditory and vestibular hypofunction. These results demonstrate that PMP22 is required for hearing and balance, and the protein is indispensable for the formation and maintenance of myelin in the peripheral arm of the eighth nerve. Our findings indicate that myelin abnormalities and altered signal propagation in the peripheral arm of the auditory nerve are likely causes of auditory deficits in patients with PMP22-linked neuropathies.
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Affiliation(s)
- Jeong Han Lee
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Seojin Park
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
- Prestige BioPharma, Busan 67264, South Korea
| | - Maria C Perez-Flores
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Yingying Chen
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Mincheol Kang
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
- Prestige BioPharma, Busan 67264, South Korea
| | - Jinsil Choi
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Lauren Levine
- Program in Audiology and Communication Sciences, Washington University, St. Louis 63110, Missouri
| | | | - Jie Zhao
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Lucia Notterpek
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
| | - Ebenezer N Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, Reno 89557, Nevada
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2
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Bennet BM, Pardo ID, Assaf BT, Buza E, Cramer SD, Crawford LK, Engelhardt JA, Galbreath EJ, Grubor B, Morrison JP, Osborne TS, Sharma AK, Bolon B. Scientific and Regulatory Policy Committee Technical Review: Biology and Pathology of Ganglia in Animal Species Used for Nonclinical Safety Testing. Toxicol Pathol 2023; 51:278-305. [PMID: 38047294 DOI: 10.1177/01926233231213851] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2023]
Abstract
Dorsal root ganglia (DRG), trigeminal ganglia (TG), other sensory ganglia, and autonomic ganglia may be injured by some test article classes, including anti-neoplastic chemotherapeutics, adeno-associated virus-based gene therapies, antisense oligonucleotides, nerve growth factor inhibitors, and aminoglycoside antibiotics. This article reviews ganglion anatomy, cytology, and pathology (emphasizing sensory ganglia) among common nonclinical species used in assessing product safety for such test articles (TAs). Principal histopathologic findings associated with sensory ganglion injury include neuron degeneration, necrosis, and/or loss; increased satellite glial cell and/or Schwann cell numbers; and leukocyte infiltration and/or inflammation. Secondary nerve fiber degeneration and/or glial reactions may occur in nerves, dorsal spinal nerve roots, spinal cord (dorsal and occasionally lateral funiculi), and sometimes the brainstem. Ganglion findings related to TA administration may result from TA exposure and/or trauma related to direct TA delivery into the central nervous system or ganglia. In some cases, TA-related effects may need to be differentiated from a spectrum of artifactual and/or spontaneous background changes.
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Affiliation(s)
| | | | | | - Elizabeth Buza
- University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | | | | | | | | | - James P Morrison
- Charles River Laboratories, Inc., Shrewsbury, Massachusetts, USA
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3
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Stavrou M, Kagiava A, Choudury SG, Jennings MJ, Wallace LM, Fowler AM, Heslegrave A, Richter J, Tryfonos C, Christodoulou C, Zetterberg H, Horvath R, Harper SQ, Kleopa KA. A translatable RNAi-driven gene therapy silences PMP22/Pmp22 genes and improves neuropathy in CMT1A mice. J Clin Invest 2022; 132:159814. [PMID: 35579942 PMCID: PMC9246392 DOI: 10.1172/jci159814] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 05/12/2022] [Indexed: 11/17/2022] Open
Abstract
Charcot-Marie-Tooth disease type 1A (CMT1A), the most common inherited demyelinating peripheral neuropathy, is caused by PMP22 gene duplication. Overexpression of WT PMP22 in Schwann cells destabilizes the myelin sheath, leading to demyelination and ultimately to secondary axonal loss and disability. No treatments currently exist that modify the disease course. The most direct route to CMT1A therapy will involve reducing PMP22 to normal levels. To accomplish this, we developed a gene therapy strategy to reduce PMP22 using artificial miRNAs targeting human PMP22 and mouse Pmp22 mRNAs. Our lead therapeutic miRNA, miR871, was packaged into an adeno-associated virus 9 (AAV9) vector and delivered by lumbar intrathecal injection into C61-het mice, a model of CMT1A. AAV9-miR871 efficiently transduced Schwann cells in C61-het peripheral nerves and reduced human and mouse PMP22 mRNA and protein levels. Treatment at early and late stages of the disease significantly improved multiple functional outcome measures and nerve conduction velocities. Furthermore, myelin pathology in lumbar roots and femoral motor nerves was ameliorated. The treated mice also showed reductions in circulating biomarkers of CMT1A. Taken together, our data demonstrate that AAV9-miR871–driven silencing of PMP22 rescues a CMT1A model and provides proof of principle for treating CMT1A using a translatable gene therapy approach.
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Affiliation(s)
- Marina Stavrou
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Alexia Kagiava
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Sarah G Choudury
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, United States of America
| | - Matthew J Jennings
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Lindsay M Wallace
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, United States of America
| | - Allison M Fowler
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, United States of America
| | - Amanda Heslegrave
- Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology, London, United Kingdom
| | - Jan Richter
- Department of Molecular Virology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Christina Tryfonos
- Department of Molecular Virology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Christina Christodoulou
- Department of Molecular Virology, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
| | - Henrik Zetterberg
- Institute of Laboratory Medicine, Göteborgs University, Göteborg, Sweden
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Scott Q Harper
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, United States of America
| | - Kleopas A Kleopa
- Neuroscience Department, The Cyprus Institute of Neurology and Genetics, Nicosia, Cyprus
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Abstract
Demyelinating forms of Charcot-Marie-Tooth disease (CMT) are genetically and phenotypically heterogeneous and result from highly diverse biological mechanisms including gain of function (including dominant negative effects) and loss of function. While no definitive treatment is currently available, rapid advances in defining the pathomechanisms of demyelinating CMT have led to promising pre-clinical studies, as well as emerging clinical trials. Especially promising are the recently completed pre-clinical genetic therapy studies in PMP-22, GJB1, and SH3TC2-associated neuropathies, particularly given the success of similar approaches in humans with spinal muscular atrophy and transthyretin familial polyneuropathy. This article focuses on neuropathies related to mutations in PMP-22, MPZ, and GJB1, which together comprise the most common forms of demyelinating CMT, as well as on select rarer forms for which promising treatment targets have been identified. Clinical characteristics and pathomechanisms are reviewed in detail, with emphasis on therapeutically targetable biological pathways. Also discussed are the challenges facing the CMT research community in its efforts to advance the rapidly evolving biological insights to effective clinical trials. These considerations include the limitations of currently available animal models, the need for personalized medicine approaches/allele-specific interventions for select forms of demyelinating CMT, and the increasing demand for optimal clinical outcome assessments and objective biomarkers.
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Affiliation(s)
- Vera Fridman
- Department of Neurology, University of Colorado Anschutz Medical Campus, 12631 E 17th Avenue, Mailstop B185, Room 5113C, Aurora, CO, 80045, USA.
| | - Mario A Saporta
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
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5
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Genetic mechanisms of peripheral nerve disease. Neurosci Lett 2020; 742:135357. [PMID: 33249104 DOI: 10.1016/j.neulet.2020.135357] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/24/2020] [Accepted: 09/02/2020] [Indexed: 12/17/2022]
Abstract
Peripheral neuropathies of genetic etiology are a very diverse group of disorders manifesting either as non-syndromic inherited neuropathies without significant manifestations outside the peripheral nervous system, or as part of a systemic or syndromic genetic disorder. The former and most frequent group is collectively known as Charcot-Marie-Tooth disease (CMT), with prevalence as high as 1:2,500 world-wide, and has proven to be genetically highly heterogeneous. More than 100 different genes have been identified so far to cause various CMT forms, following all possible inheritance patterns. CMT causative genes belong to several common functional pathways that are essential for the integrity of the peripheral nerve. Their discovery has provided insights into the normal biology of axons and myelinating cells, and has highlighted the molecular mechanisms including both loss of function and gain of function effects, leading to peripheral nerve degeneration. Demyelinating neuropathies result from dysfunction of genes primarily affecting myelinating Schwann cells, while axonal neuropathies are caused by genes affecting mostly neurons and their long axons. Furthermore, mutation in genes expressed outside the nervous system, as in the case of inherited amyloid neuropathies, may cause peripheral neuropathy resulting from accumulation of β-structured amyloid fibrils in peripheral nerves in addition to various organs. Increasing insights into the molecular-genetic mechanisms have revealed potential therapeutic targets. These will enable the development of novel therapeutics for genetic neuropathies that remain, in their majority, without effective treatment.
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Pantera H, Hu B, Moiseev D, Dunham C, Rashid J, Moran JJ, Krentz K, Rubinstein CD, Won S, Li J, Svaren J. Pmp22 super-enhancer deletion causes tomacula formation and conduction block in peripheral nerves. Hum Mol Genet 2020; 29:1689-1699. [PMID: 32356557 PMCID: PMC7322568 DOI: 10.1093/hmg/ddaa082] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/07/2020] [Accepted: 04/24/2020] [Indexed: 11/12/2022] Open
Abstract
Copy number variation of the peripheral nerve myelin gene Peripheral Myelin Protein 22 (PMP22) causes multiple forms of inherited peripheral neuropathy. The duplication of a 1.4 Mb segment surrounding this gene in chromosome 17p12 (c17p12) causes the most common form of Charcot-Marie-Tooth disease type 1A, whereas the reciprocal deletion of this gene causes a separate neuropathy termed hereditary neuropathy with liability to pressure palsies (HNPP). PMP22 is robustly induced in Schwann cells in early postnatal development, and several transcription factors and their cognate regulatory elements have been implicated in coordinating the gene's proper expression. We previously found that a distal super-enhancer domain was important for Pmp22 expression in vitro, with particular impact on a Schwann cell-specific alternative promoter. Here, we investigate the consequences of deleting this super-enhancer in vivo. We find that loss of the super-enhancer in mice reduces Pmp22 expression throughout development and into adulthood, with greater impact on the Schwann cell-specific promoter. Additionally, these mice display tomacula formed by excessive myelin folding, a pathological hallmark of HNPP, as have been previously observed in heterozygous Pmp22 mice as well as sural biopsies from patients with HNPP. Our findings demonstrate a mechanism by which smaller copy number variations, not including the Pmp22 gene, are sufficient to reduce gene expression and phenocopy a peripheral neuropathy caused by the HNPP-associated deletion encompassing PMP22.
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Affiliation(s)
- Harrison Pantera
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
- Molecular and Cellular Pharmacology Graduate Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Bo Hu
- Department of Neurology and Translational Neuroscience Initiative, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Daniel Moiseev
- Department of Neurology and Translational Neuroscience Initiative, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Chris Dunham
- Department of Neurology and Translational Neuroscience Initiative, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Jibraan Rashid
- Department of Neurology and Translational Neuroscience Initiative, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - John J Moran
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Kathleen Krentz
- Biotechnology Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - C Dustin Rubinstein
- Biotechnology Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Seongsik Won
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Jun Li
- Department of Neurology and Translational Neuroscience Initiative, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - John Svaren
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
- Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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7
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Lee JS, Lee JY, Song DW, Bae HS, Doo HM, Yu HS, Lee KJ, Kim HK, Hwang H, Kwak G, Kim D, Kim S, Hong YB, Lee JM, Choi BO. Targeted PMP22 TATA-box editing by CRISPR/Cas9 reduces demyelinating neuropathy of Charcot-Marie-Tooth disease type 1A in mice. Nucleic Acids Res 2020; 48:130-140. [PMID: 31713617 PMCID: PMC7145652 DOI: 10.1093/nar/gkz1070] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2019] [Revised: 10/29/2019] [Accepted: 10/31/2019] [Indexed: 12/26/2022] Open
Abstract
Charcot-Marie-Tooth 1A (CMT1A) is the most common inherited neuropathy without a known therapy, which is caused by a 1.4 Mb duplication on human chromosome 17, which includes the gene encoding the peripheral myelin protein of 22 kDa (PMP22). Overexpressed PMP22 protein from its gene duplication is thought to cause demyelination and subsequently axonal degeneration in the peripheral nervous system (PNS). Here, we targeted TATA-box of human PMP22 promoter to normalize overexpressed PMP22 level in C22 mice, a mouse model of CMT1A harboring multiple copies of human PMP22. Direct local intraneural delivery of CRISPR/Cas9 designed to target TATA-box of PMP22 before the onset of disease, downregulates gene expression of PMP22 and preserves both myelin and axons. Notably, the same approach was effective in partial rescue of demyelination even after the onset of disease. Collectively, our data present a proof-of-concept that CRISPR/Cas9-mediated targeting of TATA-box can be utilized to treat CMT1A.
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Affiliation(s)
- Ji-Su Lee
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06351, Korea
| | | | | | | | - Hyun M Doo
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06351, Korea
| | - Ho S Yu
- ToolGen, Inc., Seoul, 08501, Korea
| | | | - Hee K Kim
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea
| | - Hyun Hwang
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea
| | - Geon Kwak
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06351, Korea
| | - Daesik Kim
- Center for Genome Engineering, Institute for Basic Science (IBS), Seoul, 08826, Korea
- Department of Chemistry, Seoul National University, Seoul, 08826, Korea
| | | | - Young B Hong
- Department of Biochemistry, College of Medicine, Dong-A University, Busan 49201, Korea
| | - Jung M Lee
- School of Life Science, Handong Global University, Pohang 37554, Korea
| | - Byung-Ok Choi
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul, 06351, Korea
- Department of Neurology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, 06351, Korea
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8
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Pantera H, Shy ME, Svaren J. Regulating PMP22 expression as a dosage sensitive neuropathy gene. Brain Res 2019; 1726:146491. [PMID: 31586623 DOI: 10.1016/j.brainres.2019.146491] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 09/30/2019] [Accepted: 10/01/2019] [Indexed: 12/21/2022]
Abstract
Structural variation in the human genome has emerged as a major cause of disease as genomic data have accumulated. One of the most common structural variants associated with human disease causes the heritable neuropathy known as Charcot-Marie-Tooth (CMT) disease type 1A. This 1.4 Mb duplication causes nearly half of the CMT cases that are genetically diagnosed. The PMP22 gene is highly induced in Schwann cells during development, although its precise role in myelin formation and homeostasis is still under active investigation. The PMP22 gene can be considered as a nucleoprotein complex with enzymatic activity to produce the PMP22 transcript, and the complex is allosterically regulated by transcription factors that respond to intracellular signals and epigenomic modifications. The control of PMP22 transcript levels has been one of the major therapeutic targets of therapy development, and this review summarizes those approaches as well as efforts to characterize the regulation of the PMP22 gene.
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Affiliation(s)
- Harrison Pantera
- Molecular and Cellular Pharmacology Training Program, University of Wisconsin, Madison, WI, USA
| | - Michael E Shy
- Department of Neurology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - John Svaren
- Waisman Center and Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA.
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9
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Ahmed SG, Hadaegh F, Brenner GJ. Developing myelin specific promoters for schwannoma gene therapy. J Neurosci Methods 2019; 323:77-81. [PMID: 31125589 DOI: 10.1016/j.jneumeth.2019.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 05/09/2019] [Accepted: 05/17/2019] [Indexed: 10/26/2022]
Abstract
BACKGROUND Schwannomas are peripheral nerve sheath tumors composed entirely of Schwann-lineage cells that cause pain and sensory-motor dysfunction through compression of peripheral nerves, the spinal cord, and/or the brain stem. Treatment of schwannoma is largely limited to resection which itself has limited value. The goal of this study is to establish a technique to identify the most efficient and tissue-specific promoter for use in a schwannoma gene therapy construct. NEW METHOD This work involves transfection of schwannoma cells with adeno-associated viral vector plasmids expressing GFP under different myelin cell specific promoters. The transfected cells were evaluated for green fluorescence intensity in vitro, and in vivo after implantation into sciatic nerves of nude mice. RESULTS Our data demonstrate that myelin protein zero (MPZ, P0) and peripheral myelin protein 22 (PMP22) promoters produce greater GFP expression in schwannoma cell lines than myelin basic protein (MBP) promoter. In vitro, P0 promoter activity in schwannoma cell lines was shown to be less active than the cytomegalovirus and chicken β-actin (CBA) promoter. However, we did not observe any significant difference between the activity of the CBA and P0 promoters in a xenograft schwannoma model. COMPARISON WITH EXISTING METHODS(S) We show here the influence of the peripheral nerve microenvironment on promoter efficacy in expressing transgenes using simple transfection by lipofection followed by prompt implantation of the transfected cells into the sciatic nerve of nude mice. CONCLUSIONS We demonstrate that of the myelin specific promoters evaluated, P0 is optimal for driving expression of transgenes in schwannoma cells.
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Affiliation(s)
- Sherif G Ahmed
- Department of Anesthesiology, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, United States
| | - Farnaz Hadaegh
- Department of Anesthesiology, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, United States
| | - Gary J Brenner
- Department of Anesthesiology, Critical Care, and Pain Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, United States.
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Hall A, Choi K, Liu W, Rose J, Zhao C, Yu Y, Na Y, Cai Y, Coover RA, Lin Y, Dombi E, Kim M, Levanon D, Groner Y, Boscolo E, Pan D, Liu PP, Lu QR, Ratner N, Huang G, Wu J. RUNX represses Pmp22 to drive neurofibromagenesis. SCIENCE ADVANCES 2019; 5:eaau8389. [PMID: 31032403 PMCID: PMC6482019 DOI: 10.1126/sciadv.aau8389] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 03/12/2019] [Indexed: 05/02/2023]
Abstract
Patients with neurofibromatosis type 1 (NF1) are predisposed to develop neurofibromas, but the underlying molecular mechanisms of neurofibromagenesis are not fully understood. We showed dual genetic deletion of Runx1 and Runx3 in Schwann cells (SCs) and SC precursors delayed neurofibromagenesis and prolonged mouse survival. We identified peripheral myelin protein 22 (Pmp22/Gas3) related to neurofibroma initiation. Knockdown of Pmp22 with short hairpin RNAs increased Runx1fl/fl;Runx3fl/fl;Nf1fl/fl;DhhCre tumor-derived sphere numbers and enabled significantly more neurofibroma-like microlesions on transplantation. Conversely, overexpression of Pmp22 in mouse neurofibroma SCs decreased cell proliferation. Mechanistically, RUNX1/3 regulated alternative promoter usage and induced levels of protein expression of Pmp22 to control SC growth. Last, pharmacological inhibition of RUNX/core-binding factor β (CBFB) activity significantly reduced neurofibroma volume in vivo. Thus, we identified a signaling pathway involving RUNX1/3 suppression of Pmp22 in neurofibroma initiation and/or maintenance. Targeting disruption of RUNX/CBFB interaction might provide a novel therapy for patients with neurofibroma.
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Affiliation(s)
- Ashley Hall
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Kwangmin Choi
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Wei Liu
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Jonathan Rose
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Chuntao Zhao
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Yanan Yu
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Cancer and Cell Biology, College of Medicine, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Youjin Na
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Yuqi Cai
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Robert A. Coover
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Yi Lin
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
| | - Eva Dombi
- Pediatric Oncology Branch, National Cancer Institute, Bethesda, MD 20892, USA
| | - MiOk Kim
- Department of Epidemiology and Biostatistics, UCSF, Box 0128, 1450 3rd St. Suite 285, San Francisco, CA 94143, USA
| | - Ditsa Levanon
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Yoram Groner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Elisa Boscolo
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Dao Pan
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - P. Paul Liu
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Q. Richard Lu
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Nancy Ratner
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Gang Huang
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
| | - Jianqiang Wu
- Cincinnati Children’s Hospital Medical Center, Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, University of Cincinnati, 3333 Burnet Ave., Cincinnati, OH 45229, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA
- Corresponding author.
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11
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Pantera H, Moran JJ, Hung HA, Pak E, Dutra A, Svaren J. Regulation of the neuropathy-associated Pmp22 gene by a distal super-enhancer. Hum Mol Genet 2019; 27:2830-2839. [PMID: 29771329 DOI: 10.1093/hmg/ddy191] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 05/09/2018] [Indexed: 12/27/2022] Open
Abstract
Peripheral nerve myelination is adversely affected in the most common form of the hereditary peripheral neuropathy called Charcot-Marie-Tooth Disease. This form, classified as CMT1A, is caused by a 1.4 Mb duplication on chromosome 17, which includes the abundantly expressed Schwann cell myelin gene, Peripheral Myelin Protein 22 (PMP22). This is one of the most common copy number variants causing neurological disease. Overexpression of Pmp22 in rodent models recapitulates several aspects of neuropathy, and reduction of Pmp22 in such models results in amelioration of the neuropathy phenotype. Recently we identified a potential super-enhancer approximately 90-130 kb upstream of the Pmp22 transcription start sites. This super-enhancer encompasses a cluster of individual enhancers that have the acetylated histone H3K27 active enhancer mark, and coincides with smaller duplications identified in patients with milder CMT1A-like symptoms, where the PMP22 coding region itself was not part of the duplication. In this study, we have utilized genome editing to create a deletion of this super-enhancer to determine its role in Pmp22 regulation. Our data show a significant decrease in Pmp22 transcript expression using allele-specific internal controls. Moreover, the P2 promoter of the Pmp22 gene, which is used in other cell types, is affected, but we find that the Schwann cell-specific P1 promoter is disproportionately more sensitive to loss of the super-enhancer. These data show for the first time the requirement of these upstream enhancers for full Pmp22 expression.
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Affiliation(s)
- Harrison Pantera
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.,Molecular and Cellular Pharmacology Graduate Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - John J Moran
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Holly A Hung
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Evgenia Pak
- Cytogenetics and Microscopy Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Amalia Dutra
- Cytogenetics and Microscopy Core, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - John Svaren
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA.,Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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12
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Lopez-Anido C, Poitelon Y, Gopinath C, Moran JJ, Ma KH, Law WD, Antonellis A, Feltri ML, Svaren J. Tead1 regulates the expression of Peripheral Myelin Protein 22 during Schwann cell development. Hum Mol Genet 2016; 25:3055-3069. [PMID: 27288457 DOI: 10.1093/hmg/ddw158] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 05/14/2016] [Accepted: 05/18/2016] [Indexed: 12/17/2022] Open
Abstract
Schwann cells are myelinating glia in the peripheral nervous system that form the myelin sheath. A major cause of peripheral neuropathy is a copy number variant involving the Peripheral Myelin Protein 22 (PMP22) gene, which is located within a 1.4-Mb duplication on chromosome 17 associated with the most common form of Charcot-Marie-Tooth Disease (CMT1A). Rodent models of CMT1A have been used to show that reducing Pmp22 overexpression mitigates several aspects of a CMT1A-related phenotype. Mechanistic studies of Pmp22 regulation identified enhancers regulated by the Sox10 (SRY sex determining region Y-box 10) and Egr2/Krox20 (Early growth response protein 2) transcription factors in myelinated nerves. However, relatively little is known regarding how other transcription factors induce Pmp22 expression during Schwann cell development and myelination. Here, we examined Pmp22 enhancers as a function of cell type-specificity, nerve injury and development. While Pmp22 enhancers marked by active histone modifications were lost or remodeled after injury, we found that these enhancers were permissive in early development prior to Pmp22 upregulation. Pmp22 enhancers contain binding motifs for TEA domain (Tead) transcription factors of the Hippo signaling pathway. We discovered that Tead1 and co-activators Yap and Taz are required for Pmp22 expression, as well as for the expression of Egr2 Tead1 directly binds Pmp22 and Egr2 enhancers early in development and Tead1 binding is induced during myelination, correlating with Pmp22 expression. The data identify Tead1 as a novel regulator of Pmp22 expression during development in concert with Sox10 and Egr2.
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Affiliation(s)
- Camila Lopez-Anido
- Waisman Center, Madison, WI, USA.,Comparative Biomedical Sciences Graduate Program, Madison, WI, USA
| | | | - Chetna Gopinath
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Ki Hwan Ma
- Waisman Center, Madison, WI, USA.,Cellular and Molecular Pathology Graduate Program, Madison, WI, USA
| | - William D Law
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Anthony Antonellis
- Cellular and Molecular Biology Program, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - M Laura Feltri
- Hunter James Kelly Research Institute, Buffalo, NY, USA.,Department of Biochemistry, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY 14203, USA
| | - John Svaren
- Waisman Center, Madison, WI, USA .,Department of Comparative Biosciences, University of Wisconsin-Madison, Madison, WI 53705, USA
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13
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Li J, Parker B, Martyn C, Natarajan C, Guo J. The PMP22 gene and its related diseases. Mol Neurobiol 2012; 47:673-98. [PMID: 23224996 DOI: 10.1007/s12035-012-8370-x] [Citation(s) in RCA: 169] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/22/2012] [Indexed: 10/27/2022]
Abstract
Peripheral myelin protein-22 (PMP22) is primarily expressed in the compact myelin of the peripheral nervous system. Levels of PMP22 have to be tightly regulated since alterations of PMP22 levels by mutations of the PMP22 gene are responsible for >50 % of all patients with inherited peripheral neuropathies, including Charcot-Marie-Tooth type-1A (CMT1A) with trisomy of PMP22, hereditary neuropathy with liability to pressure palsies (HNPP) with heterozygous deletion of PMP22, and CMT1E with point mutations of PMP22. While overexpression and point-mutations of the PMP22 gene may produce gain-of-function phenotypes, deletion of PMP22 results in a loss-of-function phenotype that reveals the normal physiological functions of the PMP22 protein. In this article, we will review the basic genetics, biochemistry and molecular structure of PMP22, followed by discussion of the current understanding of pathogenic mechanisms involving in the inherited neuropathies with mutations in PMP22 gene.
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Affiliation(s)
- Jun Li
- VA Tennessee Valley Healthcare System, 1310 24th Avenue South, Nashville, TN 37212, USA.
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14
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Jones EA, Brewer MH, Srinivasan R, Krueger C, Sun G, Charney KN, Keles S, Antonellis A, Svaren J. Distal enhancers upstream of the Charcot-Marie-Tooth type 1A disease gene PMP22. Hum Mol Genet 2012; 21:1581-91. [PMID: 22180461 PMCID: PMC3298281 DOI: 10.1093/hmg/ddr595] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 12/12/2011] [Indexed: 11/14/2022] Open
Abstract
Myelin insulates axons in the peripheral nervous system to allow rapid propagation of action potentials, and proper myelination requires the precise regulation of genes encoding myelin proteins, including PMP22. The correct gene dosage of PMP22 is critical; a duplication of PMP22 is the most common cause of the peripheral neuropathy Charcot-Marie-Tooth Disease (CMT) (classified as type 1A), while a deletion of PMP22 leads to another peripheral neuropathy, hereditary neuropathy with liability to pressure palsies. Recently, duplications upstream of PMP22, but not containing the gene itself, were reported in patients with CMT1A like symptoms, suggesting that this region contains regulators of PMP22. Using chromatin immunoprecipitation analysis of two transcription factors known to upregulate PMP22-EGR2 and SOX10-we found several enhancers in this upstream region that contain open chromatin and direct reporter gene expression in tissue culture and in vivo in zebrafish. These studies provide a novel means to identify critical regulatory elements in genes that are required for myelination, and elucidate the functional significance of non-coding genomic rearrangements.
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Affiliation(s)
- Erin A. Jones
- Program in Cellular and Molecular Biology
- Waisman Center
| | | | | | | | - Guannan Sun
- Department of Statistics
- Department of Biostatistics and Medical Informatics and
| | | | - Sunduz Keles
- Department of Statistics
- Department of Biostatistics and Medical Informatics and
| | - Anthony Antonellis
- Department of Human Genetics
- Department of Neurology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - John Svaren
- Waisman Center
- Department of Comparative Biosciences, Waisman Center, University of Wisconsin, Madison, WI 53705, USA
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15
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Rao RG, Sudhakar D, Hogue CP, Amici S, Gordon LK, Braun J, Notterpek L, Goodglick L, Wadehra M. Peripheral myelin protein-22 (PMP22) modulates alpha 6 integrin expression in the human endometrium. Reprod Biol Endocrinol 2011; 9:56. [PMID: 21518455 PMCID: PMC3110552 DOI: 10.1186/1477-7827-9-56] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 04/25/2011] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND PMP22, a member of the GAS3 family of tetraspan proteins, is associated with a variety of neurological diseases. Previous studies have shown that PMP22 is expressed in proliferative endometrium, but its function within this tissue is poorly understood. In this study, we first characterized the expression of PMP22 in the human menstrual cycle and began to characterize its function in the endometrium. METHODS Using a combination of immunohistochemistry and quantitative PCR, we characterized the expression of PMP22 in both proliferative and secretory endometrium. Differences in PMP22 expression between proliferative and secretory endometrium were determined using a Mann-Whitney U test. In order to investigate the influence of PMP22 on α6 integrin expression, cells were created that ectopically overexpressed PMP22 or expressed a siRNA to inhibit its expression. These cells were analyzed for changes in integrins and binding to extracellular matrices. RESULTS In this study, we show that PMP22 expression is higher in proliferative phase than secretory phase. Functionally, we have begun to characterize the functional significance of this expression. Previous studies have suggested a link between PMP22 and α6 integrin, and therefore we asked whether PMP22 could associate or potentially modulate the expression of α6 integrin. Expression of both PMP22 and α6 integrin were detectable in endometrial epithelial and stromal cells, and we show that both proteins can associate and colocalize with each other. To understand if PMP22 directly altered the expression of a6 integrin, we examined cell lines with modulated levels of the protein. Overexpression of PMP22 was sufficient to increase α6 integrin surface expression with a concominant increase in binding to the extracellular matrix laminin, while a reduction in PMP22 suppressed α6 integrin surface expression. CONCLUSION These findings suggest a physiologic role for PMP22 on the expression of α6 integrin. We predict that this may be important for the maintainence of endometrial integrity and to the disease biology associated with altered levels of α6 integrin expression in the endometrium.
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Affiliation(s)
- Rajiv G Rao
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
| | - Deepthi Sudhakar
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
| | - Claire P Hogue
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
| | - Stephanie Amici
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Lynn K Gordon
- Department of Ophthalmology, University of California, Los Angeles, California 90095, USA
| | - Jonathan Braun
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California 90095, USA
| | - Lucia Notterpek
- Department of Neuroscience, McKnight Brain Institute, University of Florida, Gainesville, FL 32610, USA
| | - Lee Goodglick
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
- Jonsson Comprehensive Cancer Center, University of California, Los Angeles, California 90095, USA
| | - Madhuri Wadehra
- Department of Pathology and Laboratory Medicine, University of California, Los Angeles, California 90095, USA
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16
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Jones EA, Lopez-Anido C, Srinivasan R, Krueger C, Chang LW, Nagarajan R, Svaren J. Regulation of the PMP22 gene through an intronic enhancer. J Neurosci 2011; 31:4242-50. [PMID: 21411665 PMCID: PMC3100536 DOI: 10.1523/jneurosci.5893-10.2011] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 01/17/2011] [Accepted: 01/21/2011] [Indexed: 11/21/2022] Open
Abstract
Successful myelination of the peripheral nervous system depends upon induction of major protein components of myelin, such as peripheral myelin protein 22 (PMP22). Myelin stability is also sensitive to levels of PMP22, as a 1.4 Mb duplication on human chromosome 17, resulting in three copies of PMP22, is the most common cause of the peripheral neuropathy Charcot-Marie-Tooth disease. The transcription factor Egr2/Krox20 is required for induction of high level expression of Pmp22 in Schwann cells but its activation elements have not yet been determined. Using chromatin immunoprecipitation analysis of the rat Pmp22 locus, we found a major peak of Egr2 binding within the large intron of the Pmp22 gene. Analysis of a 250 bp region within the largest intron showed that it is strongly activated by Egr2 expression in reporter assays. Moreover, this region contains conserved binding sites not only for Egr2 but also for Sox10, which is also required for Schwann cell development. Our analysis shows that Sox10 is required for optimal activity of the intronic site as well as PMP22 expression. Finally, mouse transgenic analysis revealed tissue-specific expression of this intronic sequence in peripheral nerve. Overall, these data show that Egr2 and Sox10 activity are directly involved in mediating the developmental induction of Pmp22 expression.
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Affiliation(s)
| | | | - Rajini Srinivasan
- Waisman Center, University of Wisconsin, Madison, Wisconsin 53705, and
| | - Courtney Krueger
- Waisman Center, University of Wisconsin, Madison, Wisconsin 53705, and
| | - Li-Wei Chang
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - Rakesh Nagarajan
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, Missouri 63110
| | - John Svaren
- Department of Comparative Biosciences, and
- Waisman Center, University of Wisconsin, Madison, Wisconsin 53705, and
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17
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Simpson NE, Lambert WM, Watkins R, Giashuddin S, Huang SJ, Oxelmark E, Arju R, Hochman T, Goldberg JD, Schneider RJ, Reiz LFL, Soares FA, Logan SK, Garabedian MJ. High levels of Hsp90 cochaperone p23 promote tumor progression and poor prognosis in breast cancer by increasing lymph node metastases and drug resistance. Cancer Res 2010; 70:8446-56. [PMID: 20847343 DOI: 10.1158/0008-5472.can-10-1590] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
p23 is a heat shock protein 90 (Hsp90) cochaperone located in both the cytoplasm and nucleus that stabilizes unliganded steroid receptors, controls the catalytic activity of certain kinases, regulates protein-DNA dynamics, and is upregulated in several cancers. We had previously shown that p23-overexpressing MCF-7 cells (MCF-7+p23) exhibit increased invasion without affecting the estrogen-dependent proliferative response, which suggests that p23 differentially regulates genes controlling processes linked to breast tumor metastasis. To gain a comprehensive view of the effects of p23 on estrogen receptor (ER)-dependent and -independent gene expression, we profiled mRNA expression from control versus MCF-7+p23 cells in the absence and presence of estrogen. A number of p23-sensitive target genes involved in metastasis and drug resistance were identified. Most striking is that many of these genes are also misregulated in invasive breast cancers, including PMP22, ABCC3, AGR2, Sox3, TM4SF1, and p8 (NUPR1). Upregulation of the ATP-dependent transporter ABCC3 by p23 conferred resistance to the chemotherapeutic agents etoposide and doxorubicin in MCF-7+p23 cells. MCF-7+p23 cells also displayed higher levels of activated Akt and an expanded phosphoproteome relative to control cells, suggesting that elevated p23 also enhances cytoplasmic signaling pathways. For breast cancer patients, tumor stage together with high cytoplasmic p23 expression more accurately predicted disease recurrence and mortality than did stage alone. High nuclear p23 was found to be associated with high cytoplasmic p23, therefore both may promote tumor progression and poor prognosis by increasing metastatic potential and drug resistance in breast cancer patients.
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Affiliation(s)
- Natalie E Simpson
- Department of Pharmacology, and NYU Cancer Institute, NYU School of Medicine, New York, New York 10016, USA
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18
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Gess B, Lohmann C, Halfter H, Young P. Sodium-dependent vitamin C transporter 2 (SVCT2) is necessary for the uptake of L-ascorbic acid into Schwann cells. Glia 2010; 58:287-99. [PMID: 19672970 DOI: 10.1002/glia.20923] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Ascorbic acid has been shown to be an essential component for in vitro myelination and to improve the clinical and pathological phenotype of a mouse model of Charcot-Marie-tooth disease 1A. The mechanism of ascorbic acid uptake into peripheral nerves, however, has not been addressed so far. Hence, we studied the expression and activity of sodium-dependent vitamin C transporters 1 and 2 (SVCT1 and 2) in the peripheral nervous system. Using immunohistochemistry, immunoblotting, and reverse transcription PCR, we could show that SVCT1 and 2 were differentially expressed in myelinated peripheral nerve fibers and Schwann cell (SC) cultures. SVCT1 was expressed at very low levels confined to the axons, whereas SVCT2 was highly expressed both in the axons and in the SCs. SVCT2 was localized particularly in SC compartments of uncompacted myelin. Uptake assays using (14)C-labeled ascorbic acid showed transport of ascorbic acid into SC cultures. Ascorbic acid transport was dependent on the concentration of sodium, magnesium, and calcium in the extracellular medium. Treatment with the flavonoid phloretin, a known inhibitor of SVCT1 and 2, and specific RNA interference with SVCT2 caused significant reductions in ascorbic acid uptake into SCs. Phloretin-inhibited uptake of ascorbic acid was further shown in freshly dissected, cell-culture-naïve rat sciatic nerves. These results provide evidence for the first time that uptake of ascorbic acid in the peripheral nervous system is crucially dependent on the expression and activity of SVCT2.
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Affiliation(s)
- Burkhard Gess
- Department of Neurology, University of Muenster, Albert-Schweitzer-Strasse 33, Muenster, Germany
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19
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Abstract
In several individuals with a Charcot-Marie-Tooth (CMT) phenotype, we found a copy number variation (CNV) on chromosome 17p12 in the direct vicinity of the peripheral myelin protein 22 (PMP22) gene. The exact borders and size of this CNV were determined by Southern blot analysis, MLPA, vectorette PCR, and microarray hybridization analyses. All patients from six apparently unrelated families carried an identical 186-kb duplication different from the commonly reported 1.5-Mb duplication associated with CMT1A. This ancestral mutation that was not reported in the human structural variation database was only detected in affected individuals and family members. It was absent in 2124 control chromosomes and 40 patients with a chronic inflammatory demyelinating polyneuropathy (CIDP) and therefore should be regarded as causative for the disease. This variant escapes most routine diagnostic screens for CMT1A, because copy numbers of PMP22 probes were all normal. No indications were found for the involvement of the genes that are located within this duplication. A possible association of this duplication with a mutation in the PMP22 coding regions was also excluded. We suggest that this CNV proximal of the PMP22 gene leads to CMT through an unknown mechanism affecting PMP22 expression.
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20
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Verrier JD, Lau P, Hudson L, Murashov AK, Renne R, Notterpek L. Peripheral myelin protein 22 is regulated post-transcriptionally by miRNA-29a. Glia 2009; 57:1265-79. [PMID: 19170179 DOI: 10.1002/glia.20846] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Peripheral myelin protein 22 (PMP22) is a dose-sensitive, disease-associated protein primarily expressed in myelinating Schwann cells. Either reduction or overproduction of PMP22 can result in hereditary neuropathy, suggesting a requirement for correct protein expression for peripheral nerve biology. PMP22 is post-transcriptionally regulated and the 3'untranslated region (3'UTR) of the gene exerts a negative effect on translation. MicroRNAs (miRNAs) are small regulatory molecules that function at a post-transcriptional level by targeting the 3'UTR in a reverse complementary manner. We used cultured Schwann cells to demonstrate that alterations in the miRNA biogenesis pathway affect PMP22 levels, and endogenous PMP22 is subjected to miRNA regulation. GW-body formation, the proposed cytoplasmic site for miRNA-mediated repression, and Dicer expression, an RNase III family ribonuclease involved in miRNA biogenesis, are co-regulated with the differentiation state of Schwann cells. Furthermore, the levels of Dicer inversely correlate with PMP22, while the inhibition of Dicer leads to elevated PMP22. Microarray analysis of actively proliferating and differentiated Schwann cells, in conjunction with bioinformatics programs, identified several candidate PMP22-targeting miRNAs. Here we demonstrate that miR-29a binds and inhibits PMP22 reporter expression through a specific miRNA seed binding region. Over-expression of miR-29a enhances the association of PMP22 RNA with Argonaute 2, a protein involved in miRNA function, and reduces the steady-state levels of PMP22. In contrast, inhibition of endogenous miR-29a relieves the miRNA-mediated repression of PMP22. Correlation analyses of miR-29 and PMP22 in sciatic nerves reveal an inverse relationship, both developmentally and in post-crush injury. These results identify PMP22 as a target of miRNAs and suggest that myelin gene expression by Schwann cells is regulated by miRNAs.
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Affiliation(s)
- Jonathan D Verrier
- Department of Neuroscience, College of Medicine, McKnight Brain Institute, University of Florida, Gainesville, Florida 32610-0244, USA
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21
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Itou J, Suyama M, Imamura Y, Deguchi T, Fujimori K, Yuba S, Kawarabayasi Y, Kawasaki T. Functional and comparative genomics analyses of pmp22 in medaka fish. BMC Neurosci 2009; 10:60. [PMID: 19534778 PMCID: PMC2714311 DOI: 10.1186/1471-2202-10-60] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 06/17/2009] [Indexed: 01/23/2023] Open
Abstract
Background Pmp22, a member of the junction protein family Claudin/EMP/PMP22, plays an important role in myelin formation. Increase of pmp22 transcription causes peripheral neuropathy, Charcot-Marie-Tooth disease type1A (CMT1A). The pathophysiological phenotype of CMT1A is aberrant axonal myelination which induces a reduction in nerve conduction velocity (NCV). Several CMT1A model rodents have been established by overexpressing pmp22. Thus, it is thought that pmp22 expression must be tightly regulated for correct myelin formation in mammals. Interestingly, the myelin sheath is also present in other jawed vertebrates. The purpose of this study is to analyze the evolutionary conservation of the association between pmp22 transcription level and vertebrate myelin formation, and to find the conserved non-coding sequences for pmp22 regulation by comparative genomics analyses between jawed fishes and mammals. Results A transgenic pmp22 over-expression medaka fish line was established. The transgenic fish had approximately one fifth the peripheral NCV values of controls, and aberrant myelination of transgenic fish in the peripheral nerve system (PNS) was observed. We successfully confirmed that medaka fish pmp22 has the same exon-intron structure as mammals, and identified some known conserved regulatory motifs. Furthermore, we found novel conserved sequences in the first intron and 3'UTR. Conclusion Medaka fish undergo abnormalities in the PNS when pmp22 transcription increases. This result indicates that an adequate pmp22 transcription level is necessary for correct myelination of jawed vertebrates. Comparison of pmp22 orthologs between distantly related species identifies evolutionary conserved sequences that contribute to precise regulation of pmp22 expression.
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Affiliation(s)
- Junji Itou
- Department of Radiation Biomedical Science IV, Radiation Biology Center, Graduate School of Medicine, Kyoto University, Kyoto 606-8501, Japan.
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22
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Congenital hypomyelinating neuropathy with lethal conduction failure in mice carrying the Egr2 I268N mutation. J Neurosci 2009; 29:2312-21. [PMID: 19244508 DOI: 10.1523/jneurosci.2168-08.2009] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mouse models of human disease are helpful for understanding the pathogenesis of the disorder and ultimately for testing potential therapeutic agents. Here, we describe the engineering and characterization of a mouse carrying the I268N mutation in Egr2, observed in patients with recessively inherited Charcot-Marie-Tooth (CMT) disease type 4E, which is predicted to alter the ability of Egr2 to interact with the Nab transcriptional coregulatory proteins. Mice homozygous for Egr2(I268N) develop a congenital hypomyelinating neuropathy similar to their human counterparts. Egr2(I268N) is expressed at normal levels in developing nerve but is unable to interact with Nab proteins or to properly activate transcription of target genes critical for proper peripheral myelin development. Interestingly, Egr2(I268N/I268N) mutant mice maintain normal weight and have only mild tremor until 2 weeks after birth, at which point they rapidly develop worsening weakness and uniformly die within several days. Nerve electrophysiology revealed conduction block, and neuromuscular junctions showed marked terminal sprouting similar to that seen in animals with pharmacologically induced blockade of action potentials or neuromuscular transmission. These studies describe a unique animal model of CMT, whereby weakness is due to conduction block or neuromuscular junction failure rather than secondary axon loss and demonstrate that the Egr2-Nab complex is critical for proper peripheral nerve myelination.
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23
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Gregson NA, Zhang G, Pritchard J, Wang A, Sanvito L, Hayday AC, Hughes RAC. Characterization of a monoclonal antibody specific for human peripheral myelin protein 22 and its use in immunohistochemical studies of the fetal and adult nervous system. J Peripher Nerv Syst 2007; 12:2-10. [PMID: 17374097 DOI: 10.1111/j.1529-8027.2007.00112.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We produced a mouse monoclonal antibody using cDNA and peptide immunization against the putative second extra-cellular domain of human peripheral myelin protein 22 (PMP22). It reacted specifically with human PMP22 and not with other human myelin proteins and did not react with bovine, rat, or mouse PMP22. The antibody stained the compact myelin of human peripheral nerve motor and sensory axons and did not stain central nervous system tissue. PMP22 reactivity was detected in the spinal roots of the human fetus at 19-20 weeks of gestation. The staining pattern of the PMP22 antibody resembled that of a monoclonal antibody directed against the myelin protein zero.
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Affiliation(s)
- Norman A Gregson
- Department of Clinical Neuroscience, King's College London School of Medicine, Guy's Hospital, London, UK
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24
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Jang SW, LeBlanc SE, Roopra A, Wrabetz L, Svaren J. In vivo detection of Egr2 binding to target genes during peripheral nerve myelination. J Neurochem 2006; 98:1678-87. [PMID: 16923174 DOI: 10.1111/j.1471-4159.2006.04069.x] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Egr2/Krox20 is a zinc finger transactivator that regulates a diverse array of genes required for peripheral nerve myelination. Although several studies have elucidated the Egr2-regulated gene network, it is not clear if Egr2 regulates its target genes directly or indirectly through induction of other transactivators. Moreover, very few Egr2 binding sites have been identified in regulatory elements of myelin genes. To address this issue, we have successfully adapted chromatin immunoprecipitation assays to test if Egr2 binds directly to target genes in myelinating rat sciatic nerve. These experiments demonstrate direct binding of Egr2 to previously described binding sites within the Schwann cell enhancer of the myelin basic protein gene. Furthermore, we show Egr2 binding to a conserved site within the myelin-associated glycoprotein gene. Finally, our experiments provide the first evidence that Egr2 directly regulates expression of desert hedgehog, which is critically involved in development, maintenance and regeneration of multiple nerve elements including myelinated fibers. Surprisingly, this analysis has identified an apparent preponderance of Egr2 binding sites within conserved intron sequences of several myelin genes. Application of chromatin immunoprecipitation analysis to myelination in vivo will prove to be a valuable asset in assaying transcription factor binding and chromatin modifications during activation of myelin genes.
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Affiliation(s)
- Sung-Wook Jang
- Graduate Program in Cellular and Molecular Biology, University of Wisconsin, Madison, Wisconsin, USA
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Buchman CA, Roush PA, Teagle HFB, Brown CJ, Zdanski CJ, Grose JH. Auditory Neuropathy Characteristics in Children with Cochlear Nerve Deficiency. Ear Hear 2006; 27:399-408. [PMID: 16825889 DOI: 10.1097/01.aud.0000224100.30525.ab] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To describe a group of children exhibiting electrophysiologic responses characteristic of auditory neuropathy (AN) who were subsequently identified as having absent or small cochlear nerves (i.e., cochlear nerve deficiency). DESIGN A retrospective review of the clinical records, audiological testing results, and magnetic resonance imaging (MRI) studies. Fifty-one of 65 children with AN characteristics on auditory brain stem response (ABR) testing had MRI available for review. Nine (18%) of these 51 children with ABR characteristic of AN have been identified as having small (N = 2; 4%) or absent (N = 7; 14%) cochlear nerves on MRI. RESULTS Of the nine children with cochlear nerve deficiency, five (56%) were affected unilaterally and four (44%) bilaterally. Eight of nine presented after failing a newborn infant hearing screening, whereas one presented at 3 yr of age. On diagnostic ABR testing, all 9 children (9 of 13 affected ears; 69%) had evidence of a cochlear microphonic (CM) and absent neural responses in at least one ear. In the unilateral cases, AN characteristics were detected in all affected ears. In bilateral cases, at least one of the ears in each child demonstrated the AN phenotype, whereas the contralateral ear had no CM identified. Only one ear with cochlear nerve deficiency had present otoacoustic emissions as measured by distortion-product otoacoustic emissions. In children with appropriate available behavioral testing results, all ears without cochlear nerves were identified as having a profound hearing loss. Only 4 (31%) of the 13 ears with cochlear nerve deficiency had a small internal auditory canal on MRI. CONCLUSIONS Children with cochlear nerve deficiency can present with electrophysiologic evidence of AN. These children frequently refer on newborn screening examinations that use ABR-based testing methods. Similar to other causes of AN, diagnostic ABR testing will show a CM with absent neural responses. Given that 9 (18%) of 51 children with available MRI and electrophysiologic characteristics of AN in our program have been identified as having cochlear nerve deficiency makes this a relatively common diagnosis. These findings suggest that MRI is indicated for all children diagnosed with AN. Moreover, electrophysiologic evidence of unilateral AN in association with a profound hearing loss should make the clinician highly suspicious for this problem. Although children with cochlear nerve deficiency who have a small nerve may benefit from cochlear implantation or amplification, these interventions are obviously contraindicated in children with completely absent cochlear nerves.
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Affiliation(s)
- Craig A Buchman
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
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Denarier E, Forghani R, Farhadi HF, Dib S, Dionne N, Friedman HC, Lepage P, Hudson TJ, Drouin R, Peterson A. Functional organization of a Schwann cell enhancer. J Neurosci 2006; 25:11210-7. [PMID: 16319321 PMCID: PMC6725644 DOI: 10.1523/jneurosci.2596-05.2005] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Myelin basic protein (MBP) gene expression is conferred in oligodendrocytes and Schwann cells by different upstream enhancers. In Schwann cells, expression is controlled by a 422 bp enhancer lying -9 kb from the gene. We show here that it contains 22 mammalian conserved motifs > or =6 bp. To investigate their functional significance, different combinations of wild-type or mutated motifs were introduced into reporter constructs that were inserted in single copy at a common hypoxanthine phosphoribosyltransferase docking site in embryonic stem cells. Lines of transgenic mice were derived, and the subsequent qualitative and quantitative expression phenotypes were compared at different stages of maturation. In the enhancer core, seven contiguous motifs cooperate to confer Schwann cell specificity while different combinations of flanking motifs engage, at different stages of Schwann cell maturation, to modulate expression level. Mutation of a Krox-20 binding site reduces the level of reporter expression, whereas mutation of a potential Sox element silences reporter expression. This potential Sox motif was also found conserved in other Schwann cell enhancers, suggesting that it contributes widely to regulatory function. These results demonstrate a close relationship between phylogenetic footprints and regulatory function and suggest a general model of enhancer organization. Finally, this investigation demonstrates that in vivo functional analysis, supported by controlled transgenesis, can be a robust complement to molecular and bioinformatics approaches to regulatory mechanisms.
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Affiliation(s)
- Eric Denarier
- Laboratory of Developmental Biology, Molecular Oncology Group H-5, McGill University Health Centre, Montreal, Quebec, H3A 1A1, Canada
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Berger P, Niemann A, Suter U. Schwann cells and the pathogenesis of inherited motor and sensory neuropathies (Charcot-Marie-Tooth disease). Glia 2006; 54:243-57. [PMID: 16856148 DOI: 10.1002/glia.20386] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Over the last 15 years, a number of mutations in a variety of genes have been identified that lead to inherited motor and sensory neuropathies (HMSN), also called Charcot-Marie-Tooth disease (CMT). In this review we will focus on the molecular and cellular mechanisms that cause the Schwann cell pathologies observed in dysmyelinating and demyelinating forms of CMT. In most instances, the underlying gene defects alter primarily myelinating Schwann cells followed by secondary axonal degeneration. The first set of proteins affected by disease-causing mutations includes the myelin components PMP22, P0/MPZ, Cx32/GJB1, and periaxin. A second group contains the regulators of myelin gene transcription EGR2/Krox20 and SOX10. A third group is composed of intracellular Schwann cells proteins that are likely to be involved in the synthesis, transport and degradation of myelin components. These include the myotubularin-related lipid phosphatase MTMR2 and its regulatory binding partner MTMR13/SBF2, SIMPLE, and potentially also dynamin 2. Mutations affecting the mitochondrial fission factor GDAP1 may indicate an important contribution of mitochondria in myelination or myelin maintenance, whereas the functions of other identified genes, including NDRG1, KIAA1985, and the tyrosyl-tRNA synthase YARS, are not yet clear. Mutations in GDAP1, YARS, and the pleckstrin homology domain of dynamin 2 lead to an intermediate form of CMT that is characterized by moderately reduced nerve conduction velocity consistent with minor myelin deficits. Whether these phenotypes originate in Schwann cells or in neurons, or whether both cell types are directly affected, remains a challenging question. However, based on the advances in systematic gene identification in CMT and the analyses of the function and dysfunction of the affected proteins, crucially interconnected pathways in Schwann cells in health and disease have started to emerge. These networks include the control of myelin formation and stability, membrane trafficking, intracellular protein sorting and quality control, and may extend to mitochondrial dynamics and basic protein biosynthesis.
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Affiliation(s)
- Philipp Berger
- Institute of Cell Biology, Department of Biology, ETH Zürich, Zürich, Switzerland
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Zeng FG, Kong YY, Michalewski HJ, Starr A. Perceptual Consequences of Disrupted Auditory Nerve Activity. J Neurophysiol 2005; 93:3050-63. [PMID: 15615831 DOI: 10.1152/jn.00985.2004] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Perceptual consequences of disrupted auditory nerve activity were systematically studied in 21 subjects who had been clinically diagnosed with auditory neuropathy (AN), a recently defined disorder characterized by normal outer hair cell function but disrupted auditory nerve function. Neurological and electrophysical evidence suggests that disrupted auditory nerve activity is due to desynchronized or reduced neural activity or both. Psychophysical measures showed that the disrupted neural activity has minimal effects on intensity-related perception, such as loudness discrimination, pitch discrimination at high frequencies, and sound localization using interaural level differences. In contrast, the disrupted neural activity significantly impairs timing related perception, such as pitch discrimination at low frequencies, temporal integration, gap detection, temporal modulation detection, backward and forward masking, signal detection in noise, binaural beats, and sound localization using interaural time differences. These perceptual consequences are the opposite of what is typically observed in cochlear-impaired subjects who have impaired intensity perception but relatively normal temporal processing after taking their impaired intensity perception into account. These differences in perceptual consequences between auditory neuropathy and cochlear damage suggest the use of different neural codes in auditory perception: a suboptimal spike count code for intensity processing, a synchronized spike code for temporal processing, and a duplex code for frequency processing. We also proposed two underlying physiological models based on desynchronized and reduced discharge in the auditory nerve to successfully account for the observed neurological and behavioral data. These methods and measures cannot differentiate between these two AN models, but future studies using electric stimulation of the auditory nerve via a cochlear implant might. These results not only show the unique contribution of neural synchrony to sensory perception but also provide guidance for translational research in terms of better diagnosis and management of human communication disorders.
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Affiliation(s)
- Fan-Gang Zeng
- Department of Anatomy, 364 Med Surge II, Univ. of California, Irvine, CA 92697-1275, USA.
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Orfali W, Nicholson RN, Guiot MC, Peterson AC, Snipes GJ. An 8.5-kb segment of the PMP22 promoter responds to loss of axon signals during Wallerian degeneration, but does not respond to specific axonal signals during nerve regeneration. J Neurosci Res 2005; 80:37-46. [PMID: 15723356 DOI: 10.1002/jnr.20425] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Altered expression of the PMP22 gene causes Charcot-Marie-Tooth disease type 1A (CMT1A) and hereditary neuropathy with liability to pressure palsies (HNPP). We have examined the promoter activity of 8.5 kb upstream of the first coding exon of the rat peripheral myelin protein-22 (rPmp22) gene in transgenic mice. We found that the -8.5 kb rPmp22/chloramphenicol acetyl transferase (CAT)/beta-galactosidase (lacZ) construct directs reporter gene expression in a weakly developmental and tissue-specific pattern, consistent with the expression pattern of the endogenous Pmp22 gene. The -8.5 kb rPmp22/CAT/lacZ transgene responds to loss of axonal signals during Wallerian degeneration but unlike the endogenous Pmp22 gene, the transgene fails to respond to axonal signals during nerve regeneration after a sciatic nerve crush injury. In conclusion, the function of the -8.5 kb rPmp22/CAT/lacZ transgene suggests that there are separable regulatory elements in the rPmp22 gene that respond differently to axonal signals received by Schwann cells during nerve development, and during remyelination.
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Affiliation(s)
- Wayel Orfali
- Department of Pathology, Baylor College of Medicine, Houston, Texas 77030, USA
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Giambonini-Brugnoli G, Buchstaller J, Sommer L, Suter U, Mantei N. Distinct disease mechanisms in peripheral neuropathies due to altered peripheral myelin protein 22 gene dosage or a Pmp22 point mutation. Neurobiol Dis 2005; 18:656-68. [PMID: 15755691 DOI: 10.1016/j.nbd.2004.10.023] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2004] [Revised: 10/27/2004] [Accepted: 10/28/2004] [Indexed: 01/25/2023] Open
Abstract
Point mutations affecting PMP22 can cause hereditary demyelinating and dysmyelinating peripheral neuropathies. In addition, duplication and deletion of PMP22 are associated with Charcot-Marie-Tooth disease Type 1A (CMT1A) and Hereditary Neuropathy with Liability to Pressure Palsy (HNPP), respectively. This study was designed to elucidate disease processes caused by misexpression of Pmp22 and, at the same time, to gain further information on the controversial molecular function of PMP22. To this end, we took advantage of the unique resource of a set of various Pmp22 mutant mice to carry out comparative expression profiling of mutant and wild-type sciatic nerves. Tissues derived from Pmp22-/- ("knockout"), Pmp22tg (increased Pmp22 copy number), and Trembler (Tr; point mutation in Pmp22) mutant mice were analyzed at two developmental stages: (i) at postnatal day (P)4, when normal myelination has just started and primary causative defects of the mutations are expected to be apparent, and (ii) at P60, with the goal of obtaining information on secondary disease effects. Interestingly, the three Pmp22 mutants exhibited distinct profiles of gene expression, suggesting different disease mechanisms. Increased expression of genes involved in cell cycle regulation and DNA replication is characteristic and specific for the early stage in Pmp22-/- mice, supporting a primary function of PMP22 in the regulation of Schwann cell proliferation. In the Tr mutant, a distinguishing feature is the high expression of stress response genes. Both Tr and Pmp22tg mice show strongly reduced expression of genes important for cholesterol synthesis at P4, a characteristic that is common to all three mutants at P60. Finally, we have identified a number of candidate genes that may play important roles in the disease process or in myelination per se.
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Affiliation(s)
- Guya Giambonini-Brugnoli
- Institute for Cell Biology, Department of Biology, ETH-Hönggerberg, Swiss Federal Institute of Technology, Schafmattstrasse 18, CH-8093 Zürich, Switzerland
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