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Accogli A, Park YN, Lenk GM, Severino M, Scala M, Denecke J, Hempel M, Lessel D, Kortüm F, Salpietro V, de Marco P, Guerrisi S, Torella A, Nigro V, Srour M, Turro E, Labarque V, Freson K, Piatelli G, Capra V, Kitzman JO, Meisler MH. Biallelic loss-of-function variants of SLC12A9 cause lysosome dysfunction and a syndromic neurodevelopmental disorder. Genet Med 2024; 26:101097. [PMID: 38334070 DOI: 10.1016/j.gim.2024.101097] [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: 08/02/2023] [Revised: 01/31/2024] [Accepted: 02/01/2024] [Indexed: 02/10/2024] Open
Abstract
PURPOSE Pathogenic variants of FIG4 generate enlarged lysosomes and neurological and developmental disorders. To identify additional genes regulating lysosomal volume, we carried out a genome-wide activation screen to detect suppression of enlarged lysosomes in FIG4-/- cells. METHODS The CRISPR-a gene activation screen utilized sgRNAs from the promoters of protein-coding genes. Fluorescence-activated cell sorting separated cells with correction of the enlarged lysosomes from uncorrected cells. Patient variants of SLC12A9 were identified by exome or genome sequencing and studied by segregation analysis and clinical characterization. RESULTS Overexpression of SLC12A9, a solute co-transporter, corrected lysosomal swelling in FIG4-/- cells. SLC12A9 (NP_064631.2) colocalized with LAMP2 at the lysosome membrane. Biallelic variants of SLC12A9 were identified in 3 unrelated probands with neurodevelopmental disorders. Common features included intellectual disability, skeletal and brain structural abnormalities, congenital heart defects, and hypopigmented hair. Patient 1 was homozygous for nonsense variant p.(Arg615∗), patient 2 was compound heterozygous for p.(Ser109Lysfs∗20) and a large deletion, and proband 3 was compound heterozygous for p.(Glu290Glyfs∗36) and p.(Asn552Lys). Fibroblasts from proband 1 contained enlarged lysosomes that were corrected by wild-type SLC12A9 cDNA. Patient variant p.(Asn552Lys) failed to correct the lysosomal defect. CONCLUSION Impaired function of SLC12A9 results in enlarged lysosomes and a recessive disorder with a recognizable neurodevelopmental phenotype.
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Affiliation(s)
- Andrea Accogli
- Division of Medical Genetics, Department of Specialized Medicine, McGill University Health Centre (MUHC), Montreal, QC, Canada; Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Young N Park
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | | | - Marcello Scala
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health, Università Degli Studi di Genova, Genoa, Italy; Pediatric Neurology and Muscular Diseases Unit, IRCCS Istituto Giannina Gaslini, Genoa, Italy
| | - Jonas Denecke
- University Children's Hospital, University Medical Center Hamburg Eppendorf, Hamburg, Germany
| | - Maja Hempel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Davor Lessel
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fanny Kortüm
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Vincenzo Salpietro
- Department of Neuromuscular Disorders, Queen Square Institute of Neurology, University College London, London, United Kingdom; Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100, L'Aquila, Italy
| | | | | | - Annalaura Torella
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy; Department of Precision Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Vincenzo Nigro
- Telethon Institute of Genetics and Medicine (TIGEM), Naples, Italy; Department of Precision Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Myriam Srour
- Department of Human Genetics, McGill University, Montreal, QC, Canada; Department of Pediatrics, Division of Pediatric Neurology, McGill University, Montreal, QC, Canada; McGill University Health Center (MUHC) Research Institute, Montreal, QC, Canada; Montreal Neurological Institute, McGill University, Montreal, QC, Canada
| | - Ernest Turro
- Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, NY; Mindich Child Health and Development Institute, Icahn School of Medicine at Mount Sinai, New York, NY; Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Veerle Labarque
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium; Paediatric Hemato-Oncology, University Hospitals Leuven, Leuven, Belgium
| | - Kathleen Freson
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium
| | - Gianluca Piatelli
- Department of Neurosurgery, Gaslini Children's Hospital, Genoa, Italy
| | - Valeria Capra
- Genomics and Clinical Genetics, IRCCS Instituto G. Gaslini, Genoa, Italy
| | - Jacob O Kitzman
- Department of Human Genetics, University of Michigan, Ann Arbor, MI
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI.
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Qi L, Sun C, Sun S, Li A, Hu Q, Liu Y, Zhang Y. Phosphatidylinositol (3,5)-bisphosphate machinery regulates neurite thickness through neuron-specific endosomal protein NSG1/NEEP21. J Biol Chem 2022; 299:102775. [PMID: 36493904 PMCID: PMC9823133 DOI: 10.1016/j.jbc.2022.102775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Revised: 10/31/2022] [Accepted: 11/29/2022] [Indexed: 12/12/2022] Open
Abstract
Phosphatidylinositol (3,5)-bisphosphate [PtdIns(3,5)P2] is a critical signaling phospholipid involved in endolysosome homeostasis. It is synthesized by a protein complex composed of PIKfyve, Vac14, and Fig4. Defects in PtdIns(3,5)P2 synthesis underlie a number of human neurological disorders, including Charcot-Marie-Tooth disease, child onset progressive dystonia, and others. However, neuron-specific functions of PtdIns(3,5)P2 remain less understood. Here, we show that PtdIns(3,5)P2 pathway is required to maintain neurite thickness. Suppression of PIKfyve activities using either pharmacological inhibitors or RNA silencing resulted in decreased neurite thickness. We further find that the regulation of neurite thickness by PtdIns(3,5)P2 is mediated by NSG1/NEEP21, a neuron-specific endosomal protein. Knockdown of NSG1 expression also led to thinner neurites. mCherry-tagged NSG1 colocalized and interacted with proteins in the PtdIns(3,5)P2 machinery. Perturbation of PtdIns(3,5)P2 dynamics by overexpressing Fig4 or a PtdIns(3,5)P2-binding domain resulted in mislocalization of NSG1 to nonendosomal locations, and suppressing PtdIns(3,5)P2 synthesis resulted in an accumulation of NSG1 in EEA1-positive early endosomes. Importantly, overexpression of NSG1 rescued neurite thinning in PtdIns(3,5)P2-deficient CAD neurons and primary cortical neurons. Our study uncovered the role of PtdIns(3,5)P2 in the morphogenesis of neurons, which revealed a novel aspect of the pathogenesis of PtdIns(3,5)P2-related neuropathies. We also identified NSG1 as an important downstream protein of PtdIns(3,5)P2, which may provide a novel therapeutic target in neurological diseases.
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Affiliation(s)
- Lijuan Qi
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China,National Clinical Research Center for Hematologic Diseases, Jiangsu Institute of Hematology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, China
| | - Chen Sun
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Shenqing Sun
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Aiqing Li
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Qiuming Hu
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China
| | - Yaobo Liu
- Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Soochow University, Suzhou, Jiangsu, China
| | - Yanling Zhang
- Department of Biochemistry and Molecular Biology, Soochow University Medical College, Suzhou, Jiangsu, China,For correspondence: Yanling Zhang
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Lenk GM, Meisler MH. Chloroquine corrects enlarged lysosomes in FIG4 null cells and reduces neurodegeneration in Fig4 null mice. Mol Genet Metab 2022; 137:382-387. [PMID: 36434903 PMCID: PMC10364190 DOI: 10.1016/j.ymgme.2022.11.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/08/2022] [Accepted: 11/09/2022] [Indexed: 11/13/2022]
Abstract
Loss-of-function mutations of FIG4 impair the biosynthesis of PI(3,5)P2 and are responsible for rare genetic disorders including Yunis-Varón Syndrome and Charcot-Marie-Tooth Disease Type 4 J. Cultured cells deficient in FIG4 accumulate enlarged lysosomes with hyperacidic pH, due in part to impaired regulation of lysosomal ion channels and elevated intra-lysosomal osmotic pressure. We evaluated the effects of the FDA approved drug chloroquine, which is known to reduce lysosome acidity, on FIG4 deficient cell culture and on a mouse model. Chloroquine corrected the enlarged lysosomes in FIG4 null cells. In null mice, addition of chloroquine to the drinking water slowed progression of the disorder. Growth and mobility were dramatically improved during the first month of life, and spongiform degeneration of the nervous system was reduced. The median survival of Fig4 null mice was increased from 4 weeks for untreated mutants to 8 weeks with chloroquine treatment (p < 0.009). Chloroquine thus corrects the lysosomal swelling in cultured cells and ameliorates Fig4 deficiency in vivo. The improved phenotype of mice with complete loss of Fig4 suggests that chloroquine could be beneficial FIG2 in partial loss-of-function disorders such as Charcot-Marie-Tooth Type 4 J.
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Affiliation(s)
- Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109-5618, United States of America.
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109-5618, United States of America; Department of Neurology, University of Michigan, Ann Arbor, MI 48109, United States of America
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4
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Pathophysiological Heterogeneity of the BBSOA Neurodevelopmental Syndrome. Cells 2022; 11:cells11081260. [PMID: 35455940 PMCID: PMC9024734 DOI: 10.3390/cells11081260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/17/2022] [Accepted: 03/29/2022] [Indexed: 11/17/2022] Open
Abstract
The formation and maturation of the human brain is regulated by highly coordinated developmental events, such as neural cell proliferation, migration and differentiation. Any impairment of these interconnected multi-factorial processes can affect brain structure and function and lead to distinctive neurodevelopmental disorders. Here, we review the pathophysiology of the Bosch–Boonstra–Schaaf Optic Atrophy Syndrome (BBSOAS; OMIM 615722; ORPHA 401777), a recently described monogenic neurodevelopmental syndrome caused by the haploinsufficiency of NR2F1 gene, a key transcriptional regulator of brain development. Although intellectual disability, developmental delay and visual impairment are arguably the most common symptoms affecting BBSOAS patients, multiple additional features are often reported, including epilepsy, autistic traits and hypotonia. The presence of specific symptoms and their variable level of severity might depend on still poorly characterized genotype–phenotype correlations. We begin with an overview of the several mutations of NR2F1 identified to date, then further focuses on the main pathological features of BBSOAS patients, providing evidence—whenever possible—for the existing genotype–phenotype correlations. On the clinical side, we lay out an up-to-date list of clinical examinations and therapeutic interventions recommended for children with BBSOAS. On the experimental side, we describe state-of-the-art in vivo and in vitro studies aiming at deciphering the role of mouse Nr2f1, in physiological conditions and in pathological contexts, underlying the BBSOAS features. Furthermore, by modeling distinct NR2F1 genetic alterations in terms of dimer formation and nuclear receptor binding efficiencies, we attempt to estimate the total amounts of functional NR2F1 acting in developing brain cells in normal and pathological conditions. Finally, using the NR2F1 gene and BBSOAS as a paradigm of monogenic rare neurodevelopmental disorder, we aim to set the path for future explorations of causative links between impaired brain development and the appearance of symptoms in human neurological syndromes.
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5
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Presa M, Bailey RM, Davis C, Murphy T, Cook J, Walls R, Wilpan H, Bogdanik L, Lenk GM, Burgess RW, Gray SJ, Lutz C. AAV9-mediated FIG4 delivery prolongs life span in Charcot-Marie-Tooth disease type 4J mouse model. J Clin Invest 2021; 131:137159. [PMID: 33878035 PMCID: PMC8159684 DOI: 10.1172/jci137159] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 04/15/2021] [Indexed: 12/23/2022] Open
Abstract
Charcot-Marie-Tooth disease type 4J (CMT4J) is caused by recessive, loss-of-function mutations in FIG4, encoding a phosphoinositol(3,5)P2-phosphatase. CMT4J patients have both neuron loss and demyelination in the peripheral nervous system, with vacuolization indicative of endosome/lysosome trafficking defects. Although the disease is highly variable, the onset is often in childhood and FIG4 mutations can dramatically shorten life span. There is currently no treatment for CMT4J. Here, we present the results of preclinical studies testing a gene-therapy approach to restoring FIG4 expression. A mouse model of CMT4J, the Fig4-pale tremor (plt) allele, was dosed with a single-stranded adeno-associated virus serotype 9 (AAV9) to deliver a codon-optimized human FIG4 sequence. Untreated, Fig4plt/plt mice have a median survival of approximately 5 weeks. When treated with the AAV9-FIG4 vector at P1 or P4, mice survived at least 1 year, with largely normal gross motor performance and little sign of neuropathy by neurophysiological or histopathological evaluation. When mice were treated at P7 or P11, life span was still significantly prolonged and peripheral nerve function was improved, but rescue was less complete. No unanticipated adverse effects were observed. Therefore, AAV9-mediated delivery of FIG4 is a well-tolerated and efficacious strategy in a mouse model of CMT4J.
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Affiliation(s)
| | - Rachel M. Bailey
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | | | - Tara Murphy
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Jenn Cook
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | - Randy Walls
- The Jackson Laboratory, Bar Harbor, Maine, USA
| | | | | | - Guy M. Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Steven J. Gray
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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6
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Bao W, Wang X, Luo L, Ni R. The Lysosomal Storage Disorder Due to fig4a Mutation Causes Robust Liver Vacuolation in Zebrafish. Zebrafish 2021; 18:175-183. [PMID: 33909505 DOI: 10.1089/zeb.2020.1911] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The phospholipid phosphatase FIG4/Fig4 is a subunit of PIKFYVE/Pikfyve kinase complex that synthesizes phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2), a key regulator of endolysosomal trafficking and function. Loss of FIG4/Fig4 leads to intracellular deficiency of PI(3,5)P2 signaling and multiple endolysosomal defects. Previous works were focused on the effects of FIG4/Fig4 mutations in the nervous and musculoskeletal systems in human clinical and animal studies. In this study, we describe a zebrafish recessive mutant cq35 showing robust liver vacuolation and lethality, with a predicted truncating mutation in fig4a gene. The liver vacuolation progress in fig4a mutant was reversible after regaining normal fig4a transcripts. The hepatic vacuolation pathology was identified as abnormal lysosomal storage with numerous accumulated cargoes, including autophagy intermediates, and caused progressive degeneration of bile canaliculi in mutant liver. These hepatic pathological details of fig4a mutant were repeated in zebrafish pikfyve mutant. Thus, zebrafish possess the conserved structural and functional mechanisms in Pikfyve kinase complex, based on which, pikfyve mutant phenotype covered fig4a mutant phenotype in their double mutant. Our findings represent the first description of the in vivo defects caused by FIG4/Fig4 mutation or PI(3,5)P2 deficiency in liver, and reveal the conserved complex mechanisms associated with FIG4/Fig4-deficient disorders in zebrafish.
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Affiliation(s)
- Wandong Bao
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China
| | - Xinjuan Wang
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China
| | - Lingfei Luo
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China
| | - Rui Ni
- Key Laboratory of Freshwater Fish Reproduction and Development, Ministry of Education, Laboratory of Molecular Developmental Biology, School of Life Sciences, Southwest University, Chongqing, China
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7
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Wright GC, Brown R, Grayton H, Livingston JH, Park SM, Parker APJ, Patel A, Simonic I, Thomas AG, Vadlamani G, Horvath R, Harijan PD. Clinical and radiological characterization of novel FIG4-related combined system disease with neuropathy. Clin Genet 2020; 98:147-154. [PMID: 32385905 DOI: 10.1111/cge.13771] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 04/30/2020] [Accepted: 05/03/2020] [Indexed: 01/21/2023]
Abstract
Variants in the FIG4 gene, which encodes a phosphatidylinositol-3,5-bisphosphatase lead to obstruction of endocytic trafficking, causing accumulation of enlarged vesicles in murine peripheral neurons and fibroblasts. Bi-allelic pathogenic variants in FIG4 are associated with neurological disorders including Charcot-Marie-Tooth disease type-4J (CMT4J) and Yunis-Varón syndrome (YVS). We present four probands from three unrelated families, all homozygous for a recurrent FIG4 missense variant c.506A>C p.(Tyr169Ser), with a novel phenotype involving features of both CMT4J and YVS. Three presented with infant-onset dystonia and one with hypotonia. All have depressed lower limb reflexes and distal muscle weakness, two have nerve conduction studies (NCS) consistent with severe sensorimotor demyelinating peripheral neuropathy and one had NCS showing patchy intermediate/mildly reduced motor conduction velocities. All have cognitive impairment and three have swallowing difficulties. MRI showed cerebellar atrophy and bilateral T2 hyperintense medullary swellings in all patients. These children represent a novel clinicoradiological phenotype and suggest that phenotypes associated with FIG4 missense variants do not neatly fall into previously described diagnoses but can present with variable features. Analysis of this gene should be considered in patients with central and peripheral neurological signs and medullary radiological changes, providing earlier diagnosis and informing reproductive choices.
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Affiliation(s)
- Georgia C Wright
- University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom
| | - Richard Brown
- Paediatrics, North West Anglia NHS Foundation Trust, Peterborough, United Kingdom
| | - Hannah Grayton
- Department of Clinical Genetics, Addenbrooke's Hospital, East Anglian Genetics Service, Cambridge, United Kingdom
| | - John H Livingston
- Paediatric Neurology, The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, United Kingdom
| | - Soo-Mi Park
- Department of Clinical Genetics, Addenbrooke's Hospital, East Anglian Genetics Service, Cambridge, United Kingdom
| | - Alasdair P J Parker
- University of Cambridge School of Clinical Medicine, Cambridge, United Kingdom.,Paediatric Neurology, Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
| | - Anjla Patel
- Department of Clinical Neurophysiology, Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
| | - Ingrid Simonic
- Department of Clinical Genetics, Addenbrooke's Hospital, East Anglian Genetics Service, Cambridge, United Kingdom
| | - Adam G Thomas
- Neuroradiology, Queens Medical Centre, Nottingham University Hospitals NHS Trust, Nottingham, United Kingdom
| | - Gayatri Vadlamani
- Paediatric Neurology, The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, United Kingdom
| | - Rita Horvath
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, United Kingdom
| | - Pooja D Harijan
- Paediatric Neurology, Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
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8
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Smith TP, Sahoo PK, Kar AN, Twiss JL. Intra-axonal mechanisms driving axon regeneration. Brain Res 2020; 1740:146864. [PMID: 32360100 DOI: 10.1016/j.brainres.2020.146864] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2020] [Revised: 04/24/2020] [Accepted: 04/27/2020] [Indexed: 12/27/2022]
Abstract
Traumatic injury to the peripheral and central nervous systems very often causes axotomy, where an axon loses connections with its target resulting in loss of function. The axon segments distal to the injury site lose connection with the cell body and degenerate. Axotomized neurons in the periphery can spontaneously mount a regenerative response and reconnect to their denervated target tissues, though this is rarely complete in humans. In contrast, spontaneous regeneration rarely occurs after axotomy in the spinal cord and brain. Here, we concentrate on the mechanisms underlying this spontaneous regeneration in the peripheral nervous system, focusing on events initiated from the axon that support regenerative growth. We contrast this with what is known for axonal injury responses in the central nervous system. Considering the neuropathy focus of this special issue, we further draw parallels and distinctions between the injury-response mechanisms that initiate regenerative gene expression programs and those that are known to trigger axon degeneration.
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Affiliation(s)
- Terika P Smith
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Pabitra K Sahoo
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Amar N Kar
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.
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Morelli KH, Hatton CL, Harper SQ, Burgess RW. Gene therapies for axonal neuropathies: Available strategies, successes to date, and what to target next. Brain Res 2020; 1732:146683. [PMID: 32001243 DOI: 10.1016/j.brainres.2020.146683] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 01/23/2020] [Accepted: 01/24/2020] [Indexed: 12/20/2022]
Abstract
Nearly one-hundred loci in the human genome have been associated with different forms of Charcot-Marie-Tooth disease (CMT) and related inherited neuropathies. Despite this wealth of gene targets, treatment options are still extremely limited, and clear "druggable" pathways are not obvious for many of these mutations. However, recent advances in gene therapies are beginning to circumvent this challenge. Each type of CMT is a monogenic disorder, and the cellular targets are usually well-defined and typically include peripheral neurons or Schwann cells. In addition, the genetic mechanism is often also clear, with loss-of-function mutations requiring restoration of gene expression, and gain-of-function or dominant-negative mutations requiring silencing of the mutant allele. These factors combine to make CMT a good target for developing genetic therapies. Here we will review the state of relatively established gene therapy approaches, including viral vector-mediated gene replacement and antisense oligonucleotides for exon skipping, altering splicing, and gene knockdown. We will also describe earlier stage approaches for allele-specific knockdown and CRIPSR/Cas9 gene editing. We will next describe how these various approaches have been deployed in clinical and preclinical studies. Finally, we will evaluate various forms of CMT as candidates for gene therapy based on the current understanding of their genetics, cellular/tissue targets, validated animal models, and availability of patient populations and natural history data.
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Affiliation(s)
- Kathryn H Morelli
- The Jackson Laboratory, Bar Harbor, ME 04609, USA; The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA
| | | | - Scott Q Harper
- Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA
| | - Robert W Burgess
- The Jackson Laboratory, Bar Harbor, ME 04609, USA; The Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME 04469, USA.
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Identification of CR43467 encoding a long non-coding RNA as a novel genetic interactant with dFIG4, a CMT-causing gene. Exp Cell Res 2019; 386:111711. [PMID: 31704059 DOI: 10.1016/j.yexcr.2019.111711] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 10/30/2019] [Accepted: 11/01/2019] [Indexed: 12/15/2022]
Abstract
The eye imaginal disc-specific knockdown of dFIG4, a Drosophila homolog of FIG4 that is one of the Charcot-Marie-Tooth disease (CMT)-causing genes, induces an aberrant adult compound eye morphology, the so-called rough eye phenotype. We previously performed modifier screening on the dFIG4 knockdown-induced rough eye phenotype and identified several genes, including CR18854, encoding a long non-coding RNA (lncRNA) as genetic interactants with dFIG4. In the present study, in more extensive genetic screening, we found that the deletion of a gene locus encoding both Odorant rector 46a (Or46a) and lncRNA CR43467 effectively suppressed the rough eye phenotype induced by the knockdown of dFIG4. Both genes were located on the same locus, but oriented in opposite directions. In order to identify which of these genes is responsible for the suppression of the rough eye phenotype, we established a CR43467-specific knockdown line using the CRISPR-dCas9 system. By using this system, we demonstrated that the CR43467 gene, but not the Or46a gene, genetically interacted with the dFIG4 gene. The knockdown of CR43467 rescued the reductions in the length of synaptic branches and number of boutons at neuromuscular junctions induced by the knockdown of dFIG4. The vacuole enlargement phenotype induced by the fat body-specific dFIG4 knockdown was also effectively suppressed by the knockdown of CR43467. The knockdown of CR43467 also suppressed the rough eye phenotype induced by other peripheral neuropathy-related genes, such as dCOA7, dHADHB, and dPDHB. We herein identified another gene encoding lncRNA, CR43467 as a genetic interactant with the CMT-causing gene.
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11
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Bellio M, Caux M, Vauclard A, Chicanne G, Gratacap MP, Terrisse AD, Severin S, Payrastre B. Phosphatidylinositol 3 monophosphate metabolizing enzymes in blood platelet production and in thrombosis. Adv Biol Regul 2019; 75:100664. [PMID: 31604685 DOI: 10.1016/j.jbior.2019.100664] [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: 09/02/2019] [Revised: 09/19/2019] [Accepted: 09/30/2019] [Indexed: 02/09/2023]
Abstract
Blood platelets, produced by the fragmentation of megakaryocytes, play a key role in hemostasis and thrombosis. Being implicated in atherothrombosis and other thromboembolic disorders, they represent a major therapeutic target for antithrombotic drug development. Several recent studies have highlighted an important role for the lipid phosphatidylinositol 3 monophosphate (PtdIns3P) in megakaryocytes and platelets. PtdIns3P, present in small amounts in mammalian cells, is involved in the control of endocytic trafficking and autophagy. Its metabolism is finely regulated by specific kinases and phosphatases. Class II (α, β and γ) and III (Vps34) phosphoinositide-3-kinases (PI3Ks), INPP4 and Fig4 are involved in the production of PtdIns3P whereas PIKFyve, myotubularins (MTMs) and type II PIPK metabolize PtdIns3P. By regulating the turnover of different pools of PtdIns3P, class II (PI3KC2α) and class III (Vps34) PI3Ks have been recently involved in the regulation of platelet production and functions. These pools of PtdIns3P appear to modulate membrane organization and intracellular trafficking. Moreover, PIKFyve and INPP4 have been recently implicated in arterial thrombosis. In this review, we will discuss the role of PtdIns3P metabolizing enzymes in platelet production and function. Potential new anti-thrombotic therapeutic perspectives based on inhibitors targeting specifically PtdIns3P metabolizing enzymes will also be commented.
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Affiliation(s)
- Marie Bellio
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Manuella Caux
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Alicia Vauclard
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Gaëtan Chicanne
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Marie-Pierre Gratacap
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Anne-Dominique Terrisse
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Sonia Severin
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Bernard Payrastre
- Inserm U1048 and Université Paul Sabatier, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France; Laboratoire d'Hématologie, Hopital Universitaire de Toulouse, Toulouse, France.
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12
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Mironova YA, Lin JP, Kalinski AL, Huffman LD, Lenk GM, Havton LA, Meisler MH, Giger RJ. Protective role of the lipid phosphatase Fig4 in the adult nervous system. Hum Mol Genet 2019; 27:2443-2453. [PMID: 29688489 DOI: 10.1093/hmg/ddy145] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Accepted: 04/16/2018] [Indexed: 12/11/2022] Open
Abstract
The signaling lipid phosphatidylinositol 3,5-bisphosphate, PI(3,5)P2, functions in vesicular trafficking through the endo-lysosomal compartment. Cellular levels of PI(3,5)P2 are regulated by an enzyme complex comprised of the kinase PIKFYVE, the phosphatase FIG4, and the scaffold protein VAC14. Mutations of human FIG4 cause inherited disorders including Charcot-Marie-Tooth disease type 4J, polymicrogyria with epilepsy, and Yunis-Varón syndrome. Constitutive Fig4-/- mice exhibit intention tremor, spongiform degeneration of neural tissue, hypomyelination, and juvenile lethality. To determine whether PI(3,5)P2 is required in the adult, we generated Fig4flox/-; CAG-creER mice and carried out tamoxifen-induced gene ablation. Global ablation in adulthood leads to wasting, tremor, and motor impairment. Death follows within 2 months of tamoxifen treatment, demonstrating a life-long requirement for Fig4. Histological examinations of the sciatic nerve revealed profound Wallerian degeneration of myelinated fibers, but not C-fiber axons in Remak bundles. In optic nerve sections, myelinated fibers appear morphologically intact and carry compound action potentials at normal velocity and amplitude. However, when iKO mice are challenged with a chemical white matter lesion, repair of damaged CNS myelin is significantly delayed, demonstrating a novel role for Fig4 in remyelination. Thus, in the adult PNS Fig4 is required to protect myelinated axons from Wallerian degeneration. In the adult CNS, Fig4 is dispensable for fiber stability and nerve conduction, but is required for the timely repair of damaged white matter. The greater vulnerability of the PNS to Fig4 deficiency in the mouse is consistent with clinical observations in patients with Charcot-Marie-Tooth disease.
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Affiliation(s)
- Yevgeniya A Mironova
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.,Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jing-Ping Lin
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ashley L Kalinski
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Lucas D Huffman
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.,Interdepartmental Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Leif A Havton
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Miriam H Meisler
- Interdepartmental Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI, USA.,Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA.,Interdepartmental Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, USA.,Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, USA
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13
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Lenk GM, Berry IR, Stutterd CA, Blyth M, Green L, Vadlamani G, Warren D, Craven I, Fanjul-Fernandez M, Rodriguez-Casero V, Lockhart PJ, Vanderver A, Simons C, Gibb S, Sadedin S, White SM, Christodoulou J, Skibina O, Ruddle J, Tan TY, Leventer RJ, Livingston JH, Meisler MH. Cerebral hypomyelination associated with biallelic variants of FIG4. Hum Mutat 2019; 40:619-630. [PMID: 30740813 DOI: 10.1002/humu.23720] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/11/2018] [Accepted: 02/06/2019] [Indexed: 01/07/2023]
Abstract
The lipid phosphatase gene FIG4 is responsible for Yunis-Varón syndrome and Charcot-Marie-Tooth disease Type 4J, a peripheral neuropathy. We now describe four families with FIG4 variants and prominent abnormalities of central nervous system (CNS) white matter (leukoencephalopathy), with onset in early childhood, ranging from severe hypomyelination to mild undermyelination, in addition to peripheral neuropathy. Affected individuals inherited biallelic FIG4 variants from heterozygous parents. Cultured fibroblasts exhibit enlarged vacuoles characteristic of FIG4 dysfunction. Two unrelated families segregate the same G > A variant in the +1 position of intron 21 in the homozygous state in one family and compound heterozygous in the other. This mutation in the splice donor site of exon 21 results in read-through from exon 20 into intron 20 and truncation of the final 115 C-terminal amino acids of FIG4, with retention of partial function. The observed CNS white matter disorder in these families is consistent with the myelination defects in the FIG4 null mouse and the known role of FIG4 in oligodendrocyte maturation. The families described here the expanded clinical spectrum of FIG4 deficiency to include leukoencephalopathy.
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Affiliation(s)
- Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
| | - Ian R Berry
- Leeds Genetics Laboratory, The Leeds Teaching Hospitals NHS Trust, St James's University Hospital, Leeds, UK
| | - Chloe A Stutterd
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Royal Children's Hospital, Melbourne, Australia
| | - Moira Blyth
- Yorkshire Regional Genetics Service, The Leeds Teaching Hospitals NHS Trust, Chapel Allerton Hospital, Leeds, UK
| | - Lydia Green
- Paediatric Neurology, The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, UK
| | - Gayatri Vadlamani
- Paediatric Neurology, The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, UK
| | - Daniel Warren
- The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, UK
| | - Ian Craven
- The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, UK
| | - Miriam Fanjul-Fernandez
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | | | - Paul J Lockhart
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | - Adeline Vanderver
- Division of Neurology, Children's Hospital of Philadelphia and Perlman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Cas Simons
- Murdoch Children's Research Institute, Melbourne, Australia.,Institute for Molecular Bioscience, University of Queensland, St Lucia, Australia
| | - Susan Gibb
- Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Royal Children's Hospital, Melbourne, Australia
| | - Simon Sadedin
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia
| | | | - Susan M White
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Victorian Clinical Genetics Services, Melbourne, Australia
| | - John Christodoulou
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Victorian Clinical Genetics Services, Melbourne, Australia
| | - Olga Skibina
- Eastern Health Neurosciences, Box Hill Hospital, Monash University, Melbourne, Australia
| | - Jonathan Ruddle
- Royal Children's Hospital, Melbourne, Australia.,Centre for Eye Research Australia Ltd, East Melbourne, Victoria, Australia.,Department of Ophthalmology, University of Melbourne, Melbourne, Australia
| | - Tiong Y Tan
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Victorian Clinical Genetics Services, Melbourne, Australia
| | - Richard J Leventer
- Murdoch Children's Research Institute, Melbourne, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Australia.,Royal Children's Hospital, Melbourne, Australia
| | - John H Livingston
- Paediatric Neurology, The Leeds Teaching Hospitals NHS Trust, Leeds General Infirmary, Leeds, UK
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan
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14
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Albrecht S, Korr S, Nowack L, Narayanan V, Starost L, Stortz F, Araúzo‐Bravo MJ, Meuth SG, Kuhlmann T, Hundehege P. The K
2P
‐channel TASK1 affects Oligodendroglial differentiation but not myelin restoration. Glia 2019; 67:870-883. [DOI: 10.1002/glia.23577] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 11/23/2018] [Accepted: 11/26/2018] [Indexed: 12/14/2022]
Affiliation(s)
- Stefanie Albrecht
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
| | - Sabrina Korr
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
- Department of Neurology with Institute of Translational NeurologyUniversity Hospital Münster Münster Germany
- Cells in Motion, Cluster of Excellence Münster Germany
| | - Luise Nowack
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
- Department of Neurology with Institute of Translational NeurologyUniversity Hospital Münster Münster Germany
| | - Venu Narayanan
- Department of Neurology with Institute of Translational NeurologyUniversity Hospital Münster Münster Germany
| | - Laura Starost
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
| | - Franziska Stortz
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
| | - Marcos J. Araúzo‐Bravo
- Group of Computational Biology and Systems Biomedicine, Biodonostia Health Research Institute San Sebastian Spain
- IKERBASQUE, Basque Foundation for Science Bilbao Spain
| | - Sven G. Meuth
- Department of Neurology with Institute of Translational NeurologyUniversity Hospital Münster Münster Germany
- Cells in Motion, Cluster of Excellence Münster Germany
| | - Tanja Kuhlmann
- Institute of NeuropathologyUniversity Hospital Münster Münster Germany
| | - Petra Hundehege
- Department of Neurology with Institute of Translational NeurologyUniversity Hospital Münster Münster Germany
- Cells in Motion, Cluster of Excellence Münster Germany
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15
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Hayashi C, Suzuki N. Heterogeneity of Oligodendrocytes and Their Precursor Cells. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1190:53-62. [PMID: 31760638 DOI: 10.1007/978-981-32-9636-7_5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
While oligodendrocytes have been thought to be homogenous, a number of reports have indicated evidences of the heterogeneity of oligodendrocytes and their precursor cells, OPCs. Almost a century ago, Del Río Hortega found three and four types of oligodendrocytes with regions where they exist and their morphologies, respectively. Interfascicular oligodendrocytes are one of the three regional dependent types and are the most typical oligodendendroglial cells that myelinate axonal fibers in the white matter tracts. In the other two, perineuronal oligodendrocyes function as reserve cells for remyelination and regulate neuronal excitability, whereas perivascular oligodendrocytes may play a role in metabolic support of axons. Among the four morphological categories, type I and II oligodendrocytes form many myelin sheaths on small-diameter axons and specific signal is required for the myelination of small-diameter axons. Type III and IV oligodendrocytes myelinate a few number of axons/or one axon, whose diameters are large. A recent comprehensive gene expression analysis with single-cell RNA sequencing identifies six different populations in mature oligodendrocytes and only one population in OPCs. However, OPCs are not uniformed developmentally and regionally. Further, the capacity of OPC differentiation depends on the environments and conditions of the tissues. Taken together, oligodendrocytes and OPCs are diverse as the other cell types in the CNS. The orchestration of these cells with their specialized functions is critical for proper functioning of the CNS.
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Affiliation(s)
- Chikako Hayashi
- Department of Molecular and Cellular Biology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.,Department of Biochemistry and Biophysics, Graduate School of Health Care Sciences, TMDU, Tokyo, Japan
| | - Nobuharu Suzuki
- Department of Molecular and Cellular Biology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan. .,Department of Biochemistry and Biophysics, Graduate School of Health Care Sciences, TMDU, Tokyo, Japan.
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16
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Muraoka Y, Nakamura A, Tanaka R, Suda K, Azuma Y, Kushimura Y, Lo Piccolo L, Yoshida H, Mizuta I, Tokuda T, Mizuno T, Nakagawa M, Yamaguchi M. Genetic screening of the genes interacting with Drosophila FIG4 identified a novel link between CMT-causing gene and long noncoding RNAs. Exp Neurol 2018; 310:1-13. [PMID: 30165075 DOI: 10.1016/j.expneurol.2018.08.009] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Revised: 08/08/2018] [Accepted: 08/21/2018] [Indexed: 12/18/2022]
Abstract
Neuron-specific knockdown of the dFIG4 gene, a Drosophila homologue of human FIG4 and one of the causative genes for Charcot-Marie-Tooth disease (CMT), reduces the locomotive abilities of adult flies, as well as causing defects at neuromuscular junctions, such as reduced synaptic branch length in presynaptic terminals of the motor neurons in third instar larvae. Eye imaginal disc-specific knockdown of dFIG4 induces abnormal morphology of the adult compound eye, the rough eye phenotype. In this study, we carried out modifier screening of the dFIG4 knockdown-induced rough eye phenotype using a set of chromosomal deficiency lines on the second chromosome. By genetic screening, we detected 9 and 15 chromosomal regions whose deletions either suppressed or enhanced the rough eye phenotype induced by the dFIG4 knockdown. By further genetic screening with mutants of individual genes in one of these chromosomal regions, we identified the gene CR18854 that suppressed the rough eye phenotype and the loss-of-cone cell phenotype. The CR18854 gene encodes a long non-coding RNA (lncRNA) consisting of 2566 bases. Mutation and knockdown of CR18854 patially suppressed the enlarged lysosome phenotype induced by Fat body-specific knockdown of dFIG4. Further characterization of CR18854, and a few other lncRNAs in relation to dFIG4 in neuron, using neuron-specific dFIG4 knockdown flies indicated a genetic link between the dFIG4 gene and lncRNAs including CR18854 and hsrω. We also obtained data indicating genetic interaction between CR18854 and Cabeza, a Drosophila homologue of human FUS, which is one of the causing genes for amyotrophic lateral sclerosis (ALS). These results suggest that lncRNAs such as CR18854 and hsrω are involved in a common pathway in CMT and ALS pathogenesis.
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Affiliation(s)
- Yuuka Muraoka
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Aya Nakamura
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Ryo Tanaka
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Kojiro Suda
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Yumiko Azuma
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Yukie Kushimura
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Luca Lo Piccolo
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Hideki Yoshida
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan
| | - Ikuko Mizuta
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Takahiko Tokuda
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan; Department of Molecular Pathobiology of Brain Diseases, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Toshiki Mizuno
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan
| | - Masanori Nakagawa
- Department of Neurology, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, 465 Kajii-cho, Kamigyo-ku, Kyoto 602-8566, Japan; North Medical Center, Kyoto Prefectural University of Medicine, 481 otokoyama, yosano-cho, yosa-gun, Kyoto 629-2291, Japan
| | - Masamitsu Yamaguchi
- Department of Applied Biology, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan; The Center for Advanced Insect Research, Kyoto Institute of Technology, Matsugasaki, Sakyo-ku, Kyoto 606-8585, Japan.
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17
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Lin JP, Mironova YA, Shrager P, Giger RJ. LRP1 regulates peroxisome biogenesis and cholesterol homeostasis in oligodendrocytes and is required for proper CNS myelin development and repair. eLife 2017; 6:30498. [PMID: 29251594 PMCID: PMC5752207 DOI: 10.7554/elife.30498] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 12/15/2017] [Indexed: 01/01/2023] Open
Abstract
Low-density lipoprotein receptor-related protein-1 (LRP1) is a large endocytic and signaling molecule broadly expressed by neurons and glia. In adult mice, global inducible (Lrp1flox/flox;CAG-CreER) or oligodendrocyte (OL)-lineage specific ablation (Lrp1flox/flox;Pdgfra-CreER) of Lrp1 attenuates repair of damaged white matter. In oligodendrocyte progenitor cells (OPCs), Lrp1 is required for cholesterol homeostasis and differentiation into mature OLs. Lrp1-deficient OPC/OLs show a strong increase in the sterol-regulatory element-binding protein-2 yet are unable to maintain normal cholesterol levels, suggesting more global metabolic deficits. Mechanistic studies revealed a decrease in peroxisomal biogenesis factor-2 and fewer peroxisomes in OL processes. Treatment of Lrp1−/− OPCs with cholesterol or activation of peroxisome proliferator-activated receptor-γ with pioglitazone alone is not sufficient to promote differentiation; however, when combined, cholesterol and pioglitazone enhance OPC differentiation into mature OLs. Collectively, our studies reveal a novel role for Lrp1 in peroxisome biogenesis, lipid homeostasis, and OPC differentiation during white matter development and repair.
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Affiliation(s)
- Jing-Ping Lin
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, United States
| | - Yevgeniya A Mironova
- Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI, United States
| | - Peter Shrager
- Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, United States
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, MI, United States.,Cellular and Molecular Biology Graduate Program, University of Michigan Medical School, Ann Arbor, MI, United States.,Department of Neurology, University of Michigan Medical School, Ann Arbor, MI, United States.,Interdepartmental Neuroscience Graduate Program, University of Michigan Medical School, Ann Arbor, MI, United States
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18
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Yellajoshyula D, Liang CC, Pappas SS, Penati S, Yang A, Mecano R, Kumaran R, Jou S, Cookson MR, Dauer WT. The DYT6 Dystonia Protein THAP1 Regulates Myelination within the Oligodendrocyte Lineage. Dev Cell 2017; 42:52-67.e4. [PMID: 28697333 DOI: 10.1016/j.devcel.2017.06.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 04/25/2017] [Accepted: 06/07/2017] [Indexed: 11/30/2022]
Abstract
The childhood-onset motor disorder DYT6 dystonia is caused by loss-of-function mutations in the transcription factor THAP1, but the neurodevelopmental processes in which THAP1 participates are unknown. We find that THAP1 is essential for the timing of myelination initiation during CNS maturation. Conditional deletion of THAP1 in the CNS retards maturation of the oligodendrocyte (OL) lineage, delaying myelination and causing persistent motor deficits. The CNS myelination defect results from a cell-autonomous requirement for THAP1 in the OL lineage and is recapitulated in developmental assays performed on OL progenitor cells purified from Thap1 null mice. Loss of THAP1 function disrupts a core set of OL maturation genes and reduces the DNA occupancy of YY1, a transcription factor required for OL maturation. These studies establish a role for THAP1 transcriptional regulation at the inception of myelination and implicate abnormal timing of myelination in the pathogenesis of childhood-onset dystonia.
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Affiliation(s)
- Dhananjay Yellajoshyula
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Chun-Chi Liang
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Samuel S Pappas
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Silvia Penati
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Angela Yang
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Rodan Mecano
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Ravindran Kumaran
- Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute of Aging, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - Stephanie Jou
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA
| | - Mark R Cookson
- Cell Biology and Gene Expression Section, Laboratory of Neurogenetics, National Institute of Aging, National Institutes of Health, 9000 Rockville Pike, Bethesda, MD 20892, USA
| | - William T Dauer
- Department of Neurology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA; Department of Cell and Developmental Biology, University of Michigan Medical School, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA; VAAAHS, University of Michigan Medical School, University of Michigan, 109 Zina Pitcher Place, Ann Arbor, MI 48109, USA.
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19
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Wan G, Corfas G. Transient auditory nerve demyelination as a new mechanism for hidden hearing loss. Nat Commun 2017; 8:14487. [PMID: 28211470 PMCID: PMC5321746 DOI: 10.1038/ncomms14487] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/04/2017] [Indexed: 12/31/2022] Open
Abstract
Hidden hearing loss (HHL) is a recently described auditory neuropathy believed to contribute to speech discrimination and intelligibility deficits in people with normal audiological tests. Animals and humans with HHL have normal auditory thresholds but defective cochlear neurotransmission, that is, reduced suprathreshold amplitude of the sound-evoked auditory nerve compound action potential. Currently, the only cellular mechanism known for HHL is loss of inner hair cell synapses (synaptopathy). Here we report that transient loss of cochlear Schwann cells results in permanent auditory deficits characteristic of HHL. This auditory neuropathy is not associated with synaptic loss, but rather with disruption of the first heminodes at the auditory nerve peripheral terminal. Thus, this study identifies a new mechanism for HHL, highlights the long-term consequences of transient Schwann cell loss on hearing and might provide insights into the causes of the auditory deficits reported in patients that recover from acute demyelinating diseases such as Guillain–Barré syndrome. Hidden hearing loss (HHL) is an auditory neuropathy that impairs one's ability to hear, particularly in a noisy environment. Here the authors show that in mice, transient loss of cochlear Schwann cells results in permanent disruption of the cochlear heminodal structure, leading to auditory deficits characteristic of HHL.
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Affiliation(s)
- Guoqiang Wan
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA.,MOE Key Laboratory of Model Animals for Disease Study, Model Animal Research Center of Nanjing University, Nanjing, Jiangsu Province, China
| | - Gabriel Corfas
- Department of Otolaryngology-Head and Neck Surgery, Kresge Hearing Research Institute, University of Michigan, 1150 West Medical Center Drive, Ann Arbor, Michigan 48109, USA
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20
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Sebastian A, Volk SW, Halai P, Colthurst J, Paus R, Bayat A. Enhanced Neurogenic Biomarker Expression and Reinnervation in Human Acute Skin Wounds Treated by Electrical Stimulation. J Invest Dermatol 2016; 137:737-747. [PMID: 27856290 DOI: 10.1016/j.jid.2016.09.038] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 08/20/2016] [Accepted: 09/19/2016] [Indexed: 11/27/2022]
Abstract
Electrical stimulation (ES) is known to promote cutaneous healing; however, its ability to regulate reinnervation remains unclear. First, we show that ES treatment of human acute cutaneous wounds (n = 40) increased reinnervation. Next, to define neurophysiologic mechanisms through which ES affects repair, microarray analysis of wound biopsy samples was performed on days 3, 7, 10, and 14 after wounding. This identified neural differentiation biomarkers TUBB3 (melanocyte development and neuronal marker) and its upstream molecule FIG4 (phosphatidylinositol (3,5)-bisphosphate 5-phosphatase) as significantly up-regulated after ES treatment. To demonstrate a functional ES-TUBB3 axis in cutaneous healing, we showed increased TUBB3+ melanocytes and melanogenesis plus FIG4 and nerve growth factor expression, suggesting higher cellular differentiation. In support of this role of ES to regulate neural crest-derived cell fate and differentiation in vivo, knockdown of FIG4 in neuroblastoma cells resulted in vacuologenesis and cell degeneration, whereas ES treatment after FIG4-small interfering RNA transfection enhanced neural differentiation, survival, and integrity. Further characterization showed increased TUBB3+ and protein gene product 9.5+ Merkel cells during in vivo repair, after ES. We demonstrate that ES contributes to increased expression of neural differentiation biomarkers, reinnervation, and expansion of melanocyte and Merkel cell pool during repair. Targeted ES-assisted acceleration of healing has significant clinical implications.
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Affiliation(s)
- Anil Sebastian
- Plastic Surgery Research Group, Dermatology Research Centre, Institute of Inflammation & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | - Susan W Volk
- Section of Surgery, Department of Clinical Studies-Philadelphia, University of Pennsylvania School of Veterinary Medicine, Philadelphia, Pennsylvania, USA
| | - Poonam Halai
- Plastic Surgery Research Group, Dermatology Research Centre, Institute of Inflammation & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK
| | | | - Ralf Paus
- Hair Follicle Biology Research Group, Dermatology Research Centre, Institute of Inflammation & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK; Department of Dermatology, University of Muenster, Muenster, Germany
| | - Ardeshir Bayat
- Plastic Surgery Research Group, Dermatology Research Centre, Institute of Inflammation & Repair, Faculty of Medical and Human Sciences, University of Manchester, Manchester, UK.
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21
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Shrager P, Youngman M. Preferential conduction block of myelinated axons by nitric oxide. J Neurosci Res 2016; 95:1402-1414. [PMID: 27614087 DOI: 10.1002/jnr.23918] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 08/04/2016] [Accepted: 08/22/2016] [Indexed: 12/14/2022]
Abstract
Conduction block by nitric oxide (NO) was examined in myelinated and unmyelinated axons from both the central nervous system and peripheral nervous system. In rat vagus nerves, mouse optic nerves at P12-P23, adult and developing mouse sciatic nerves, and mouse spinal cords, myelinated fibers were preferentially blocked reversibly by concentrations of NO similar to those encountered in inflammatory lesions. The possibility that these differences between myelinated and unmyelinated axons are due to the normal developmental substitution of Na+ channel subtype Nav 1.6 for Nav 1.2 at nodes of Ranvier was tested by repeating experiments on mice null for Nav 1.6. Results were unchanged in this mutant. In shiverer optic nerve, which has only scattered regions with nodes of Ranvier, only the fastest component of the compound action potential was reduced. NO was compared with three other methods of blocking conduction: low Na+ , high K+ , and tetrodotoxin (TTX). In each of these three cases, unmyelinated axons lost conduction simultaneously with myelinated fibers. From changes in conduction velocity in myelinated axons as they were blocked, it was ascertained that NO acted most similarly to TTX. It was concluded that NO likely interacts with axonal Na+ channels through an intermediate that is associated with myelin. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Peter Shrager
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York
| | - Margaret Youngman
- Department of Neuroscience, University of Rochester Medical Center, Rochester, New York
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22
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Mironova YA, Lenk GM, Lin JP, Lee SJ, Twiss JL, Vaccari I, Bolino A, Havton LA, Min SH, Abrams CS, Shrager P, Meisler MH, Giger RJ. PI(3,5)P2 biosynthesis regulates oligodendrocyte differentiation by intrinsic and extrinsic mechanisms. eLife 2016; 5. [PMID: 27008179 PMCID: PMC4889328 DOI: 10.7554/elife.13023] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 03/23/2016] [Indexed: 12/18/2022] Open
Abstract
Proper development of the CNS axon-glia unit requires bi-directional communication between axons and oligodendrocytes (OLs). We show that the signaling lipid phosphatidylinositol-3,5-bisphosphate [PI(3,5)P2] is required in neurons and in OLs for normal CNS myelination. In mice, mutations of Fig4, Pikfyve or Vac14, encoding key components of the PI(3,5)P2 biosynthetic complex, each lead to impaired OL maturation, severe CNS hypomyelination and delayed propagation of compound action potentials. Primary OLs deficient in Fig4 accumulate large LAMP1+ and Rab7+ vesicular structures and exhibit reduced membrane sheet expansion. PI(3,5)P2 deficiency leads to accumulation of myelin-associated glycoprotein (MAG) in LAMP1+perinuclear vesicles that fail to migrate to the nascent myelin sheet. Live-cell imaging of OLs after genetic or pharmacological inhibition of PI(3,5)P2 synthesis revealed impaired trafficking of plasma membrane-derived MAG through the endolysosomal system in primary cells and brain tissue. Collectively, our studies identify PI(3,5)P2 as a key regulator of myelin membrane trafficking and myelinogenesis. DOI:http://dx.doi.org/10.7554/eLife.13023.001 Neurons communicate with each other through long cable-like extensions called axons. An insulating sheath called myelin (or white matter) surrounds each axon, and allows electrical impulses to travel more quickly. Cells in the brain called oligodendrocytes produce myelin. If the myelin sheath is not properly formed during development, or is damaged by injury or disease, the consequences can include paralysis, impaired thought, and loss of vision. Oligodendrocytes have complex shapes, and each can generate myelin for as many as 50 axons. Oligodendrocytes produce the building blocks of myelin inside their cell bodies, by following instructions encoded by genes within the nucleus. However, the signals that regulate the trafficking of these components to the myelin sheath are poorly understood. Mironova et al. set out to determine whether signaling molecules called phosphoinositides help oligodendrocytes to mature and move myelin building blocks from the cell bodies to remote contact points with axons. Genetic techniques were used to manipulate an enzyme complex in mice that controls the production and turnover of a phosphoinositide called PI(3,5)P2. Mironova et al. found that reducing the levels of PI(3,5)P2 in oligodendrocytes caused the trafficking of certain myelin building blocks to stall. Key myelin components instead accumulated inside bubble-like structures near the oligodendrocyte’s cell body. This showed that PI(3,5)P2 in oligodendrocytes is essential for generating myelin. Further experiments then revealed that reducing PI(3,5)P2 in the neurons themselves indirectly prevented the oligodendrocytes from maturing. This suggests that PI(3,5)P2 also takes part in communication between axons and oligodendrocytes during development of the myelin sheath. A key next step will be to identify the regulatory mechanisms that control the production of PI(3,5)P2 in oligodendrocytes and neurons. Future studies could also explore what PI(3,5)P2 acts upon inside the axons, and which signaling molecules support the maturation of oligodendrocytes. Finally, it remains unclear whether PI(3,5)P2signaling is also required for stabilizing mature myelin, and for repairing myelin after injury in the adult brain. Further work could therefore address these questions as well. DOI:http://dx.doi.org/10.7554/eLife.13023.002
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Affiliation(s)
- Yevgeniya A Mironova
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, United States.,Cellular and Molecular Biology Graduate Program, University of Michigan School of Medicine, Ann Arbor, United States
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, United States
| | - Jing-Ping Lin
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, United States
| | - Seung Joon Lee
- Department of Biological Sciences, University of South Carolina, Columbia, United States
| | - Jeffery L Twiss
- Department of Biological Sciences, University of South Carolina, Columbia, United States
| | - Ilaria Vaccari
- Human Inherited Neuropathies Unit, INSPE-Institute for Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy
| | - Alessandra Bolino
- Human Inherited Neuropathies Unit, INSPE-Institute for Experimental Neurology, San Raffaele Scientific Institute, Milan, Italy
| | - Leif A Havton
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, United States
| | - Sang H Min
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, United States
| | - Charles S Abrams
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, United States
| | - Peter Shrager
- Department of Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, United States
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, United States.,Department of Neurology, University of Michigan School of Medicine, Ann Arbor, United States
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan School of Medicine, Ann Arbor, United States.,Department of Neurology, University of Michigan School of Medicine, Ann Arbor, United States
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23
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Kyotani A, Azuma Y, Yamamoto I, Yoshida H, Mizuta I, Mizuno T, Nakagawa M, Tokuda T, Yamaguchi M. Knockdown of the Drosophila FIG4 induces deficient locomotive behavior, shortening of motor neuron, axonal targeting aberration, reduction of life span and defects in eye development. Exp Neurol 2016; 277:86-95. [DOI: 10.1016/j.expneurol.2015.12.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 12/14/2015] [Accepted: 12/15/2015] [Indexed: 01/19/2023]
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24
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Alonso A, Pulido R. The extended human PTPome: a growing tyrosine phosphatase family. FEBS J 2015; 283:1404-29. [PMID: 26573778 DOI: 10.1111/febs.13600] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Revised: 10/02/2015] [Accepted: 11/13/2015] [Indexed: 12/13/2022]
Abstract
Tyr phosphatases are, by definition, enzymes that dephosphorylate phospho-Tyr (pTyr) from proteins. This activity is found in several structurally diverse protein families, including the protein Tyr phosphatase (PTP), arsenate reductase, rhodanese, haloacid dehalogenase (HAD) and His phosphatase (HP) families. Most of these families include members with substrate specificity for non-pTyr substrates, such as phospho-Ser/phospho-Thr, phosphoinositides, phosphorylated carbohydrates, mRNAs, or inorganic moieties. A Cys is essential for catalysis in PTPs, rhodanese and arsenate reductase enzymes, whereas this work is performed by an Asp in HAD phosphatases and by a His in HPs, via a catalytic mechanism shared by all of the different families. The category that contains most Tyr phosphatases is the PTP family, which, although it received its name from this activity, includes Ser, Thr, inositide, carbohydrate and RNA phosphatases, as well as some inactive pseudophosphatase proteins. Here, we propose an extended collection of human Tyr phosphatases, which we call the extended human PTPome. The addition of new members (SACs, paladin, INPP4s, TMEM55s, SSU72, and acid phosphatases) to the currently categorized PTP group of enzymes means that the extended human PTPome contains up to 125 proteins, of which ~ 40 are selective for pTyr. We set criteria to ascribe proteins to the extended PTPome, and summarize the more important features of the new PTPome members in the context of their phosphatase activity and their relationship with human disease.
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Affiliation(s)
- Andrés Alonso
- Instituto de Biología y Genética Molecular (IBGM), CSIC-Universidad de Valladolid, Valladolid, Spain
| | - Rafael Pulido
- Biocruces Health Research Institute, Barakaldo, Spain.,IKERBASQUE, Basque Foundation for Science, Bilbao, Spain
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25
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Lenk GM, Frei CM, Miller AC, Wallen RC, Mironova YA, Giger RJ, Meisler MH. Rescue of neurodegeneration in the Fig4 null mouse by a catalytically inactive FIG4 transgene. Hum Mol Genet 2015; 25:340-7. [PMID: 26604144 DOI: 10.1093/hmg/ddv480] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 11/16/2015] [Indexed: 11/13/2022] Open
Abstract
The lipid phosphatase FIG4 is a subunit of the protein complex that regulates biosynthesis of the signaling lipid PI(3,5)P2. Mutations of FIG4 result in juvenile lethality and spongiform neurodegeneration in the mouse, and are responsible for the human disorders Charcot-Marie-Tooth disease, Yunis-Varon syndrome and polymicrogyria with seizures. We previously demonstrated that conditional expression of a wild-type FIG4 transgene in neurons is sufficient to rescue most of the abnormalities of Fig4 null mice, including juvenile lethality and extensive neurodegeneration. To evaluate the contribution of the phosphatase activity to the in vivo function of Fig4, we introduced the mutation p.Cys486Ser into the Sac phosphatase active-site motif CX5RT. Transfection of the Fig4(Cys486Ser) cDNA into cultured Fig4(-/-) fibroblasts was effective in preventing vacuolization. The neuronal expression of an NSE-Fig4(Cys486Ser) transgene in vivo prevented the neonatal neurodegeneration and juvenile lethality seen in Fig4 null mice. These observations demonstrate that the catalytically inactive FIG4 protein provides significant function, possibly by stabilization of the PI(3,5)P2 biosynthetic complex and/or localization of the complex to endolysosomal vesicles. Despite this partial rescue, later in life the NSE-Fig4(Cys486Ser) transgenic mice display significant abnormalities that include hydrocephalus, defective myelination and reduced lifespan. The late onset phenotype of the NSE-Fig4(Cys486Ser) transgenic mice demonstrates that the phosphatase activity of FIG4 has an essential role in vivo.
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Affiliation(s)
| | | | | | | | | | - Roman J Giger
- Department of Cell and Developmental Biology and Department of Neurology, University of Michigan, 4909 Buhl, Ann Arbor, MI 48109-5618, USA
| | - Miriam H Meisler
- Department of Human Genetics, Department of Neurology, University of Michigan, 4909 Buhl, Ann Arbor, MI 48109-5618, USA
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26
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Carbajal KS, Mironova Y, Ulrich-Lewis JT, Kulkarni D, Grifka-Walk HM, Huber AK, Shrager P, Giger RJ, Segal BM. Th Cell Diversity in Experimental Autoimmune Encephalomyelitis and Multiple Sclerosis. THE JOURNAL OF IMMUNOLOGY 2015; 195:2552-9. [PMID: 26238492 DOI: 10.4049/jimmunol.1501097] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Accepted: 07/08/2015] [Indexed: 11/19/2022]
Abstract
Multiple sclerosis (MS) is believed to be initiated by myelin-reactive CD4(+) Th cells. IL-12-polarized Th1 cells, IL-23-polarized Th17 cells, and Th17 cells that acquire Th1 characteristics were each implicated in autoimmune pathogenesis. It is debated whether Th cells that can drive the development of demyelinating lesions are phenotypically diverse or arise from a single lineage. In the current study, we assessed the requirement of IL-12 or IL-23 stimulation, as well as Th plasticity, for the differentiation of T cells capable of inducing CNS axon damage. We found that stable murine Th1 and Th17 cells independently transfer experimental autoimmune encephalomyelitis (widely used as an animal model of MS) in the absence of IL-23 and IL-12, respectively. Plastic Th17 cells are particularly potent mediators of demyelination and axonopathy. In parallel studies, we identified MS patients who consistently mount either IFN-γ- or IL-17-skewed responses to myelin basic protein over the course of a year. Brain magnetic resonance imaging revealed that patients with mixed IFN-γ and IL-17 responses have relatively high T1 lesion burden, a measure of permanent axon damage. Our data challenge the dogma that IL-23 and Th17 plasticity are universally required for the development of experimental autoimmune encephalomyelitis. This study definitively demonstrates that autoimmune demyelinating disease can be driven by distinct Th-polarizing factors and effector subsets, underscoring the importance of a customized approach to the pharmaceutical management of MS.
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Affiliation(s)
- Kevin S Carbajal
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Yevgeniya Mironova
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109; Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109
| | - Justin T Ulrich-Lewis
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Deven Kulkarni
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Heather M Grifka-Walk
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109; Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109
| | - Amanda K Huber
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Peter Shrager
- Department of Neurobiology and Anatomy, University of Rochester Medical Center, Rochester, NY 14642; and
| | - Roman J Giger
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109; Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109
| | - Benjamin M Segal
- Holtom-Garrett Program in Neuroimmunology, Department of Neurology, University of Michigan, Ann Arbor, MI 48109; Graduate Program in Immunology, University of Michigan, Ann Arbor, MI 48109; Neurology Service, VA Ann Arbor Healthcare System, Ann Arbor, MI 48105
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27
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Waugh MG. PIPs in neurological diseases. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1851:1066-82. [PMID: 25680866 DOI: 10.1016/j.bbalip.2015.02.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/29/2015] [Accepted: 02/01/2015] [Indexed: 12/19/2022]
Abstract
Phosphoinositide (PIP) lipids regulate many aspects of cell function in the nervous system including receptor signalling, secretion, endocytosis, migration and survival. Levels of PIPs such as PI4P, PI(4,5)P2 and PI(3,4,5)P3 are normally tightly regulated by phosphoinositide kinases and phosphatases. Deregulation of these biochemical pathways leads to lipid imbalances, usually on intracellular endosomal membranes, and these changes have been linked to a number of major neurological diseases including Alzheimer's, Parkinson's, epilepsy, stroke, cancer and a range of rarer inherited disorders including brain overgrowth syndromes, Charcot-Marie-Tooth neuropathies and neurodevelopmental conditions such as Lowe's syndrome. This article analyses recent progress in this area and explains how PIP lipids are involved, to varying degrees, in almost every class of neurological disease. This article is part of a Special Issue entitled Brain Lipids.
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Affiliation(s)
- Mark G Waugh
- Lipid and Membrane Biology Group, Institute for Liver and Digestive Health, UCL, Royal Free Campus, Rowland Hill Street, London NW3 2PF, United Kingdom.
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28
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Min SH, Suzuki A, Stalker TJ, Zhao L, Wang Y, McKennan C, Riese MJ, Guzman JF, Zhang S, Lian L, Joshi R, Meng R, Seeholzer SH, Choi JK, Koretzky G, Marks MS, Abrams CS. Loss of PIKfyve in platelets causes a lysosomal disease leading to inflammation and thrombosis in mice. Nat Commun 2014; 5:4691. [PMID: 25178411 DOI: 10.1038/ncomms5691] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Accepted: 07/13/2014] [Indexed: 01/07/2023] Open
Abstract
PIKfyve is essential for the synthesis of phosphatidylinositol-3,5-bisphosphate [PtdIns(3,5)P2] and for the regulation of endolysosomal membrane dynamics in mammals. PtdIns(3,5)P2 deficiency causes neurodegeneration in mice and humans, but the role of PtdIns(3,5)P2 in non-neural tissues is poorly understood. Here we show that platelet-specific ablation of PIKfyve in mice leads to accelerated arterial thrombosis, and, unexpectedly, also to inappropriate inflammatory responses characterized by macrophage accumulation in multiple tissues. These multiorgan defects are attenuated by platelet depletion in vivo, confirming that they reflect a platelet-specific process. PIKfyve ablation in platelets induces defective maturation and excessive storage of lysosomal enzymes that are released upon platelet activation. Impairing lysosome secretion from PIKfyve-null platelets in vivo markedly attenuates the multiorgan defects, suggesting that platelet lysosome secretion contributes to pathogenesis. Our findings identify PIKfyve as an essential regulator for platelet lysosome homeostasis, and demonstrate the contributions of platelet lysosomes to inflammation, arterial thrombosis and macrophage biology.
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Affiliation(s)
- Sang H Min
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Aae Suzuki
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Timothy J Stalker
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Liang Zhao
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Yuhuan Wang
- Division of Hematology, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Chris McKennan
- Proteomics Core, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - Matthew J Riese
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Jessica F Guzman
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Suhong Zhang
- Department of Pharmacology, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Lurong Lian
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Rohan Joshi
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Ronghua Meng
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Steven H Seeholzer
- Proteomics Core, The Children's Hospital of Philadelphia, Philadelphia, Pennsylvania 19104, USA
| | - John K Choi
- Department of Pathology, St Jude Children's Research Hospital, Memphis, Tennessee 38105, USA
| | - Gary Koretzky
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Michael S Marks
- Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia and the University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
| | - Charles S Abrams
- Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 19104, USA
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29
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Abstract
The endolysosomal system and autophagy are essential components of macromolecular turnover in eukaryotic cells. The low-abundance signaling lipid PI(3,5)P2 is a key regulator of this pathway. Analysis of mouse models with defects in PI(3,5)P2 biosynthesis has revealed the unique dependence of the mammalian nervous system on this signaling pathway. This insight led to the discovery of the molecular basis for several human neurological disorders, including Charcot-Marie-Tooth disease and Yunis-Varon syndrome. Spontaneous mutants, conditional knockouts, transgenic lines, and gene-trap alleles of Fig4, Vac14, and Pikfyve (Fab1) in the mouse have provided novel information regarding the role of PI(3,5)P2in vivo. This review summarizes what has been learned from mouse models and highlights the utility of manipulating complex signaling pathways in vivo.
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Affiliation(s)
- Guy M Lenk
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan, Ann Arbor, Michigan, USA.
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30
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McCartney AJ, Zhang Y, Weisman LS. Phosphatidylinositol 3,5-bisphosphate: low abundance, high significance. Bioessays 2013; 36:52-64. [PMID: 24323921 DOI: 10.1002/bies.201300012] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Recent studies of the low abundant signaling lipid, phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2 ), reveal an intriguingly diverse list of downstream pathways, the intertwined relationship between PI(3,5)P2 and PI5P, as well as links to neurodegenerative diseases. Derived from the structural lipid phosphatidylinositol, PI(3,5)P2 is dynamically generated on multiple cellular compartments where interactions with an increasing list of effectors regulate many cellular pathways. A complex of proteins that includes Fab1/PIKfyve, Vac14, and Fig4/Sac3 mediates the biosynthesis of PI(3,5)P2 , and mutations that disrupt complex function and/or formation cause profound consequences in cells. Surprisingly, mutations in this pathway are linked with neurological diseases, including Charcot-Marie-Tooth syndrome and amyotrophic lateral sclerosis. Future studies of PI(3,5)P2 and PI5P are likely to expand the roles of these lipids in regulation of cellular functions, as well as provide new approaches for treatment of some neurological diseases.
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Affiliation(s)
- Amber J McCartney
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI, USA
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31
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Reifler A, Lenk GM, Li X, Groom L, Brooks SV, Wilson D, Bowerson M, Dirksen RT, Meisler MH, Dowling JJ. Murine Fig4 is dispensable for muscle development but required for muscle function. Skelet Muscle 2013; 3:21. [PMID: 24004519 PMCID: PMC3844516 DOI: 10.1186/2044-5040-3-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Accepted: 07/29/2013] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND Phosphatidylinositol phosphates (PIPs) are low-abundance phospholipids that participate in a range of cellular processes, including cell migration and membrane traffic. PIP levels and subcellular distribution are regulated by a series of lipid kinases and phosphatases. In skeletal muscle, PIPs and their enzymatic regulators serve critically important functions exemplified by mutations of the PIP phosphatase MTM1 in myotubular myopathy (MTM), a severe muscle disease characterized by impaired muscle structure and abnormal excitation-contraction coupling. FIG4 functions as a PIP phosphatase that participates in both the synthesis and breakdown of phosphatidylinositol 3,5-bisphosphate (PI(3,5)P2). Mutation of FIG4 results in a severe neurodegenerative disorder in mice and a progressive peripheral polyneuropathy in humans. The effect of FIG4 mutation on skeletal muscle has yet to be examined. METHODS Herein we characterize the impact of FIG4 on skeletal muscle development and function using the spontaneously occurring mouse mutant pale tremor (plt), a mouse line with a loss of function mutation in Fig4. RESULTS In plt mice, we characterized abnormalities in skeletal muscle, including reduced muscle size and specific force generation. We also uncovered ultrastructural abnormalities and increased programmed cell death. Conversely, we detected no structural or functional abnormalities to suggest impairment of excitation-contraction coupling, a process previously shown to be influenced by PI(3,5)P2 levels. Conditional rescue of Fig4 mutation in neurons prevented overt muscle weakness and the development of obvious muscle abnormalities, suggesting that the changes observed in the plt mice were primarily related to denervation of skeletal muscle. On the basis of the ability of reduced FIG4 levels to rescue aspects of Mtmr2-dependent neuropathy, we evaluated the effect of Fig4 haploinsufficiency on the myopathy of Mtm1-knockout mice. Male mice with a compound Fig4+/-/Mtm1-/Y genotype displayed no improvements in muscle histology, muscle size or overall survival, indicating that FIG4 reduction does not ameliorate the Mtm1-knockout phenotype. CONCLUSIONS Overall, these data indicate that loss of Fig4 impairs skeletal muscle function but does not significantly affect its structural development.
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Affiliation(s)
- Aaron Reifler
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109-2200, USA
| | - Guy M Lenk
- Department of Human Genetics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - Xingli Li
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - Linda Groom
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Susan V Brooks
- Molecular and Integrative Physiology, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - Desmond Wilson
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - Michyla Bowerson
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - Robert T Dirksen
- Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY 14642, USA
| | - Miriam H Meisler
- Department of Human Genetics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
| | - James J Dowling
- Department of Pediatrics, University of Michigan Medical Center, Ann Arbor, MI 48109-2200, USA
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Kon T, Mori F, Tanji K, Miki Y, Toyoshima Y, Yoshida M, Sasaki H, Kakita A, Takahashi H, Wakabayashi K. ALS-associated protein FIG4 is localized in Pick and Lewy bodies, and also neuronal nuclear inclusions, in polyglutamine and intranuclear inclusion body diseases. Neuropathology 2013; 34:19-26. [DOI: 10.1111/neup.12056] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2013] [Accepted: 06/25/2013] [Indexed: 12/12/2022]
Affiliation(s)
- Tomoya Kon
- Department of Neuropathology; Hirosaki University Graduate School of Medicine; Hirosaki
| | - Fumiaki Mori
- Department of Neuropathology; Hirosaki University Graduate School of Medicine; Hirosaki
| | - Kunikazu Tanji
- Department of Neuropathology; Hirosaki University Graduate School of Medicine; Hirosaki
| | - Yasuo Miki
- Department of Neuropathology; Hirosaki University Graduate School of Medicine; Hirosaki
| | | | - Mari Yoshida
- Department of Neuropathology; Aichi Medical University; Nagakute
| | - Hidenao Sasaki
- Department of Neurology; Hokkaido University Graduate School of Medicine; Sapporo Japan
| | - Akiyoshi Kakita
- Department of Pathological Neuroscience; Center for Bioresource-based Researches; University of Niigata; Niigata
| | | | - Koichi Wakabayashi
- Department of Neuropathology; Hirosaki University Graduate School of Medicine; Hirosaki
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Abstract
Phosphoinositides (PIs) make up only a small fraction of cellular phospholipids, yet they control almost all aspects of a cell's life and death. These lipids gained tremendous research interest as plasma membrane signaling molecules when discovered in the 1970s and 1980s. Research in the last 15 years has added a wide range of biological processes regulated by PIs, turning these lipids into one of the most universal signaling entities in eukaryotic cells. PIs control organelle biology by regulating vesicular trafficking, but they also modulate lipid distribution and metabolism via their close relationship with lipid transfer proteins. PIs regulate ion channels, pumps, and transporters and control both endocytic and exocytic processes. The nuclear phosphoinositides have grown from being an epiphenomenon to a research area of its own. As expected from such pleiotropic regulators, derangements of phosphoinositide metabolism are responsible for a number of human diseases ranging from rare genetic disorders to the most common ones such as cancer, obesity, and diabetes. Moreover, it is increasingly evident that a number of infectious agents hijack the PI regulatory systems of host cells for their intracellular movements, replication, and assembly. As a result, PI converting enzymes began to be noticed by pharmaceutical companies as potential therapeutic targets. This review is an attempt to give an overview of this enormous research field focusing on major developments in diverse areas of basic science linked to cellular physiology and disease.
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Affiliation(s)
- Tamas Balla
- Section on Molecular Signal Transduction, Program for Developmental Neuroscience, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Campeau P, Lenk G, Lu J, Bae Y, Burrage L, Turnpenny P, Román Corona-Rivera J, Morandi L, Mora M, Reutter H, Vulto-van Silfhout A, Faivre L, Haan E, Gibbs R, Meisler M, Lee B. Yunis-Varón syndrome is caused by mutations in FIG4, encoding a phosphoinositide phosphatase. Am J Hum Genet 2013; 92:781-91. [PMID: 23623387 DOI: 10.1016/j.ajhg.2013.03.020] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 03/17/2013] [Accepted: 03/25/2013] [Indexed: 12/14/2022] Open
Abstract
Yunis-Varón syndrome (YVS) is an autosomal-recessive disorder with cleidocranial dysplasia, digital anomalies, and severe neurological involvement. Enlarged vacuoles are found in neurons, muscle, and cartilage. By whole-exome sequencing, we identified frameshift and missense mutations of FIG4 in affected individuals from three unrelated families. FIG4 encodes a phosphoinositide phosphatase required for regulation of PI(3,5)P(2) levels, and thus endosomal trafficking and autophagy. In a functional assay, both missense substitutions failed to correct the vacuolar phenotype of Fig4-null mouse fibroblasts. Homozygous Fig4-null mice exhibit features of YVS, including neurodegeneration and enlarged vacuoles in neurons. We demonstrate that Fig4-null mice also have small skeletons with reduced trabecular bone volume and cortical thickness and that cultured osteoblasts accumulate large vacuoles. Our findings demonstrate that homozygosity or compound heterozygosity for null mutations of FIG4 is responsible for YVS, the most severe known human phenotype caused by defective phosphoinositide metabolism. In contrast, in Charcot-Marie-Tooth disease type 4J (also caused by FIG4 mutations), one of the FIG4 alleles is hypomorphic and disease is limited to the peripheral nervous system. This genotype-phenotype correlation demonstrates that absence of FIG4 activity leads to central nervous system dysfunction and extensive skeletal anomalies. Our results describe a role for PI(3,5)P(2) signaling in skeletal development and maintenance.
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Yu T, Lieberman AP. Npc1 acting in neurons and glia is essential for the formation and maintenance of CNS myelin. PLoS Genet 2013; 9:e1003462. [PMID: 23593041 PMCID: PMC3623760 DOI: 10.1371/journal.pgen.1003462] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 03/04/2013] [Indexed: 01/06/2023] Open
Abstract
Cholesterol availability is rate-limiting for myelination, and prior studies have established the importance of cholesterol synthesis by oligodendrocytes for normal CNS myelination. However, the contribution of cholesterol uptake through the endocytic pathway has not been fully explored. To address this question, we used mice with a conditional null allele of the Npc1 gene, which encodes a transmembrane protein critical for mobilizing cholesterol from the endolysosomal system. Loss of function mutations in the human NPC1 gene cause Niemann-Pick type C disease, a childhood-onset neurodegenerative disorder in which intracellular lipid accumulation, abnormally swollen axons, and neuron loss underlie the occurrence of early death. Both NPC patients and Npc1 null mice exhibit myelin defects indicative of dysmyelination, although the mechanisms underlying this defect are incompletely understood. Here we use temporal and cell-type-specific gene deletion in order to define effects on CNS myelination. Our results unexpectedly show that deletion of Npc1 in neurons alone leads to an arrest of oligodendrocyte maturation and to subsequent failure of myelin formation. This defect is associated with decreased activation of Fyn kinase, an integrator of axon-glial signals that normally promotes myelination. Furthermore, we show that deletion of Npc1 in oligodendrocytes results in delayed myelination at early postnatal days. Aged, oligodendocyte-specific null mutants also exhibit late stage loss of myelin proteins, followed by secondary Purkinje neuron degeneration. These data demonstrate that lipid uptake and intracellular transport by neurons and oligodendrocytes through an Npc1-dependent pathway is required for both the formation and maintenance of CNS myelin.
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Affiliation(s)
- Ting Yu
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Andrew P. Lieberman
- Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail:
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Hsu F, Mao Y. The Sac domain-containing phosphoinositide phosphatases: structure, function, and disease. ACTA ACUST UNITED AC 2013; 8:395-407. [PMID: 24860601 DOI: 10.1007/s11515-013-1258-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Phosphoinositides (PIs) have long been known to have an essential role in cell physiology. Their intracellular localization and concentration must be tightly regulated for their proper function. This spatial and temporal regulation is achieved by a large number of PI kinases and phosphatases that are present throughout eukaryotic species. One family of these enzymes contains a conserved PI phosphatase domain termed Sac. Although the Sac domain is homologous among different Sac domain-containing proteins, all appear to exhibit varied substrate specificity and subcellular localization. Dysfunctions in several members of this family are implicated in a range of human diseases such as cardiac hypertrophy, bipolar disorder, Down's syndrome, Charcot-Marie-Tooth disease (CMT) and Amyotrophic Lateral Sclerosis (ALS). In plant, several Sac domain-containing proteins have been implicated in the stress response, chloroplast function and polarized secretion. In this review, we focus on recent findings in the family of Sac domain-containing PI phosphatases in yeast, mammal and plant, including the structural analysis into the mechanism of enzymatic activity, cellular functions, and their roles in disease pathophysiology.
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Affiliation(s)
- FoSheng Hsu
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Yuxin Mao
- Weill Institute for Cell and Molecular Biology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
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Martyn C, Li J. Fig4 deficiency: a newly emerged lysosomal storage disorder? Prog Neurobiol 2012; 101-102:35-45. [PMID: 23165282 DOI: 10.1016/j.pneurobio.2012.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Revised: 09/07/2012] [Accepted: 11/09/2012] [Indexed: 12/31/2022]
Abstract
FIG4 (Sac3 in mammals) is a 5'-phosphoinositide phosphatase that coordinates the turnover of phosphatidylinositol-3,5-bisphosphate (PI(3,5)P(2)), a very low abundance phosphoinositide. Deficiency of FIG4 severely affects the human and mouse nervous systems by causing two distinct forms of abnormal lysosomal storage. The first form occurs in spinal sensory neurons, where vacuolated endolysosomes accumulate in perinuclear regions. A second form occurs in cortical/spinal motor neurons and glia, in which enlarged endolysosomes become filled with electron dense materials in a manner indistinguishable from other lysosomal storage disorders. Humans with a deficiency of FIG4 (known as Charcot-Marie-Tooth disease type 4J or CMT4J) present with clinical and pathophysiological phenotypes indicative of spinal motor neuron degeneration and segmental demyelination. These findings reveal a signaling pathway involving FIG4 that appears to be important for lysosomal function. In this review, we discuss the biology of FIG4 and describe how the deficiency of FIG4 results in lysosomal phenotypes. We also discuss the implications of FIG4/PI(3,5)P(2) signaling in understanding other lysosomal storage diseases, neuropathies, and acquired demyelinating diseases.
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Affiliation(s)
- Colin Martyn
- VA Tennessee Valley Healthcare System, Nashville, TN, USA
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Stiles TL, Dickendesher TL, Gaultier A, Fernandez-Castaneda A, Mantuano E, Giger RJ, Gonias SL. LDL receptor-related protein-1 is a sialic-acid-independent receptor for myelin-associated glycoprotein that functions in neurite outgrowth inhibition by MAG and CNS myelin. J Cell Sci 2012; 126:209-20. [PMID: 23132925 DOI: 10.1242/jcs.113191] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
In the injured adult mammalian central nervous system (CNS), products are generated that inhibit neuronal sprouting and regeneration. In recent years, most attention has focused on the myelin-associated inhibitory proteins (MAIs) Nogo-A, OMgp, and myelin-associated glycoprotein (MAG). Binding of MAIs to neuronal cell-surface receptors leads to activation of RhoA, growth cone collapse, and neurite outgrowth inhibition. In the present study, we identify low-density lipoprotein (LDL) receptor-related protein-1 (LRP1) as a high-affinity, endocytic receptor for MAG. In contrast with previously identified MAG receptors, binding of MAG to LRP1 occurs independently of terminal sialic acids. In primary neurons, functional inactivation of LRP1 with receptor-associated protein, depletion by RNA interference (RNAi) knock-down, or LRP1 gene deletion is sufficient to significantly reverse MAG and myelin-mediated inhibition of neurite outgrowth. Similar results are observed when LRP1 is antagonized in PC12 and N2a cells. By contrast, inhibiting LRP1 does not attenuate inhibition of neurite outgrowth caused by chondroitin sulfate proteoglycans. Mechanistic studies in N2a cells showed that LRP1 and p75NTR associate in a MAG-dependent manner and that MAG-mediated activation of RhoA may involve both LRP1 and p75NTR. LRP1 derivatives that include the complement-like repeat clusters CII and CIV bind MAG and other MAIs. When CII and CIV were expressed as Fc-fusion proteins, these proteins, purified full-length LRP1 and shed LRP1 all attenuated the inhibition of neurite outgrowth caused by MAG and CNS myelin in primary neurons. Collectively, our studies identify LRP1 as a novel MAG receptor that functions in neurite outgrowth inhibition.
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Affiliation(s)
- Travis L Stiles
- Department of Pathology, University of California San Diego, La Jolla, CA 92093, USA
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Ten-m3 is required for the development of topography in the ipsilateral retinocollicular pathway. PLoS One 2012; 7:e43083. [PMID: 23028443 PMCID: PMC3446960 DOI: 10.1371/journal.pone.0043083] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Accepted: 07/16/2012] [Indexed: 11/20/2022] Open
Abstract
Background The alignment of ipsilaterally and contralaterally projecting retinal axons that view the same part of visual space is fundamental to binocular vision. While much progress has been made regarding the mechanisms which regulate contralateral topography, very little is known of the mechanisms which regulate the mapping of ipsilateral axons such that they align with their contralateral counterparts. Results Using the advantageous model provided by the mouse retinocollicular pathway, we have performed anterograde tracing experiments which demonstrate that ipsilateral retinal axons begin to form terminal zones (TZs) in the superior colliculus (SC), within the first few postnatal days. These appear mature by postnatal day 11. Importantly, TZs formed by ipsilaterally-projecting retinal axons are spatially offset from those of contralaterally-projecting axons arising from the same retinotopic location from the outset. This pattern is consistent with that required for adult visuotopy. We further demonstrate that a member of the Ten-m/Odz/Teneurin family of homophilic transmembrane glycoproteins, Ten-m3, is an essential regulator of ipsilateral retinocollicular topography. Ten-m3 mRNA is expressed in a high-medial to low-lateral gradient in the developing SC. This corresponds topographically with its high-ventral to low-dorsal retinal gradient. In Ten-m3 knockout mice, contralateral ventrotemporal axons appropriately target rostromedial SC, whereas ipsilateral axons exhibit dramatic targeting errors along both the mediolateral and rostrocaudal axes of the SC, with a caudal shift of the primary TZ, as well as the formation of secondary, caudolaterally displaced TZs. In addition to these dramatic ipsilateral-specific mapping errors, both contralateral and ipsilateral retinocollicular TZs exhibit more subtle changes in morphology. Conclusions We conclude that important aspects of adult visuotopy are established via the differential sensitivity of ipsilateral and contralateral axons to intrinsic guidance cues. Further, we show that Ten-m3 plays a critical role in this process and is particularly important for the mapping of the ipsilateral retinocollicular pathway.
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Ferguson CJ, Lenk GM, Jones JM, Grant AE, Winters JJ, Dowling JJ, Giger RJ, Meisler MH. Neuronal expression of Fig4 is both necessary and sufficient to prevent spongiform neurodegeneration. Hum Mol Genet 2012; 21:3525-34. [PMID: 22581779 DOI: 10.1093/hmg/dds179] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
FIG4 is a ubiquitously expressed phosphatase that, in complex with FAB1/PIKFYVE and VAC14, regulates the biosynthesis of the signaling lipid PI(3,5)P(2). Null mutation of Fig4 in the mouse results in spongiform degeneration of brain and peripheral ganglia, defective myelination and juvenile lethality. Partial loss-of-function of human FIG4 results in a severe form of Charcot-Marie-Tooth neuropathy. Neurons from null mice contain enlarged vacuoles derived from the endosome/lysosome pathway, and astrocytes accumulate proteins involved in autophagy. Other cellular defects include astrogliosis and microgliosis. To distinguish the contributions of neurons and glia to spongiform degeneration in the Fig4 null mouse, we expressed Fig4 under the control of the neuron-specific enolase promoter and the astrocyte-specific glial fibrillary acidic protein promoter in transgenic mice. Neuronal expression of Fig4 was sufficient to rescue cellular and neurological phenotypes including spongiform degeneration, gliosis and juvenile lethality. In contrast, expression of Fig4 in astrocytes prevented accumulation of autophagy markers and microgliosis but did not prevent spongiform degeneration or lethality. To confirm the neuronal origin of spongiform degeneration, we generated a floxed allele of Fig4 and crossed it with mice expressing the Cre recombinase from the neuron-specific synapsin promoter. Mice with conditional inactivation of Fig4 in neurons developed spongiform degeneration and the full spectrum of neurological abnormalities. The data demonstrate that expression of Fig4 in neurons is necessary and sufficient to prevent spongiform degeneration. Therapy for patients with FIG4 deficiency will therefore require correction of the deficiency in neurons.
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Affiliation(s)
- C J Ferguson
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109-6518, USA
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