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De T, Sharma P, Upilli B, Vivekanand A, Bari S, Sonakar AK, Srivastava AK, Faruq M. Spinocerebellar ataxia type 27B (SCA27B) in India: insights from a large cohort study suggest ancient origin. Neurogenetics 2024:10.1007/s10048-024-00770-y. [PMID: 38976084 DOI: 10.1007/s10048-024-00770-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Accepted: 06/25/2024] [Indexed: 07/09/2024]
Abstract
BACKGROUND The ethnic diversity of India provides a unique opportunity to study the history of the origin of mutations of genetic disorders. Spinocerebellar ataxia type 27B (SCA27B), a recently identified dominantly inherited cerebellar disorder is caused by GAA-repeat expansions in intron 1 of Fibroblast Growth Factor 14 (FGF14). Predominantly reported in the European population, we aimed to screen this mutation and study the founder haplotype of SCA27B in Indian ataxia patients. METHODS We have undertaken screening of GAA repeats in a large Indian cohort of ~ 1400 uncharacterised ataxia patients and kindreds and long-read sequencing-based GAA repeat length assessment. High throughput genotyping-based haplotype analysis was also performed. We utilized ~ 1000 Indian genomes to study the GAA at-risk expansion alleles. FINDINGS We report a high frequency of 1.83% (n = 23) of SCA27B in the uncharacterized Indian ataxia cohort. We observed several biallelic GAA expansion mutations (n = 5) with younger disease onset. We observed a risk haplotype (AATCCGTGG) flanking the FGF14-GAA locus over a 74 kb region in linkage disequilibrium. We further studied the frequency of this risk haplotype across diverse geographical population groups. The highest prevalence of the risk haplotype was observed in the European population (29.9%) followed by Indians (21.5%). The observed risk haplotype has existed through ~ 1100 generations (~ 22,000 years), assuming a correlated genealogy. INTERPRETATION This study provides valuable insights into SCA27B and its Upper Paleolithic origin in the Indian subcontinent. The high occurrence of biallelic expansion is probably relevant to the endogamous nature of the Indian population.
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Affiliation(s)
- Tiyasha De
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India
| | - Pooja Sharma
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Sector-19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh, 201002, India
| | - Bharathram Upilli
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Sector-19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh, 201002, India
| | - A Vivekanand
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India
- Academy of Scientific and Innovative Research (AcSIR), Sector-19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh, 201002, India
| | - Shreya Bari
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India
| | - Akhilesh Kumar Sonakar
- Neurology Department, Neuroscience Centre, All India Institute of Medical Sciences, Ansari Nagar, 110029, India
| | - Achal Kumar Srivastava
- Neurology Department, Neuroscience Centre, All India Institute of Medical Sciences, Ansari Nagar, 110029, India
| | - Mohammed Faruq
- Genomics and Molecular Medicine, CSIR-Institute of Genomics and Integrative Biology, Mall road, New Delhi, 110007, India.
- Academy of Scientific and Innovative Research (AcSIR), Sector-19, Kamla Nehru Nagar, Ghaziabad, Uttar Pradesh, 201002, India.
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Cui ZT, Mao ZT, Yang R, Li JJ, Jia SS, Zhao JL, Zhong FT, Yu P, Dong M. Spinocerebellar ataxias: from pathogenesis to recent therapeutic advances. Front Neurosci 2024; 18:1422442. [PMID: 38894941 PMCID: PMC11185097 DOI: 10.3389/fnins.2024.1422442] [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: 04/24/2024] [Accepted: 05/08/2024] [Indexed: 06/21/2024] Open
Abstract
Spinocerebellar ataxia is a phenotypically and genetically heterogeneous group of autosomal dominant-inherited degenerative disorders. The gene mutation spectrum includes dynamic expansions, point mutations, duplications, insertions, and deletions of varying lengths. Dynamic expansion is the most common form of mutation. Mutations often result in indistinguishable clinical phenotypes, thus requiring validation using multiple genetic testing techniques. Depending on the type of mutation, the pathogenesis may involve proteotoxicity, RNA toxicity, or protein loss-of-function. All of which may disrupt a range of cellular processes, such as impaired protein quality control pathways, ion channel dysfunction, mitochondrial dysfunction, transcriptional dysregulation, DNA damage, loss of nuclear integrity, and ultimately, impairment of neuronal function and integrity which causes diseases. Many disease-modifying therapies, such as gene editing technology, RNA interference, antisense oligonucleotides, stem cell technology, and pharmacological therapies are currently under clinical trials. However, the development of curative approaches for genetic diseases remains a global challenge, beset by technical, ethical, and other challenges. Therefore, the study of the pathogenesis of spinocerebellar ataxia is of great importance for the sustained development of disease-modifying molecular therapies.
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Affiliation(s)
- Zi-Ting Cui
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Zong-Tao Mao
- Department of Plastic and Reconstructive Surgery, The First Hospital of Jilin University, Changchun, China
| | - Rong Yang
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Jia-Jia Li
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Shan-Shan Jia
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Jian-Li Zhao
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Fang-Tian Zhong
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
| | - Peng Yu
- Department of Ophthalmology, the Second Hospital of Jilin University, Changchun, China
| | - Ming Dong
- Department of Neurology and Neuroscience Center, The First Hospital of Jilin University, Changchun, China
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Rudaks LI, Yeow D, Ng K, Deveson IW, Kennerson ML, Kumar KR. An Update on the Adult-Onset Hereditary Cerebellar Ataxias: Novel Genetic Causes and New Diagnostic Approaches. CEREBELLUM (LONDON, ENGLAND) 2024:10.1007/s12311-024-01703-z. [PMID: 38760634 DOI: 10.1007/s12311-024-01703-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/07/2024] [Indexed: 05/19/2024]
Abstract
The hereditary cerebellar ataxias (HCAs) are rare, progressive neurologic disorders caused by variants in many different genes. Inheritance may follow autosomal dominant, autosomal recessive, X-linked or mitochondrial patterns. The list of genes associated with adult-onset cerebellar ataxia is continuously growing, with several new genes discovered in the last few years. This includes short-tandem repeat (STR) expansions in RFC1, causing cerebellar ataxia, neuropathy, vestibular areflexia syndrome (CANVAS), FGF14-GAA causing spinocerebellar ataxia type 27B (SCA27B), and THAP11. In addition, the genetic basis for SCA4, has recently been identified as a STR expansion in ZFHX3. Given the large and growing number of genes, and different gene variant types, the approach to diagnostic testing for adult-onset HCA can be complex. Testing methods include targeted evaluation of STR expansions (e.g. SCAs, Friedreich ataxia, fragile X-associated tremor/ataxia syndrome, dentatorubral-pallidoluysian atrophy), next generation sequencing for conventional variants, which may include targeted gene panels, whole exome, or whole genome sequencing, followed by various potential additional tests. This review proposes a diagnostic approach for clinical testing, highlights the challenges with current testing technologies, and discusses future advances which may overcome these limitations. Implementing long-read sequencing has the potential to transform the diagnostic approach in HCA, with the overall aim to improve the diagnostic yield.
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Affiliation(s)
- Laura Ivete Rudaks
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia.
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia.
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia.
- Clinical Genetics Unit, Royal North Shore Hospital, Sydney, Australia.
| | - Dennis Yeow
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Neurodegenerative Service, Prince of Wales Hospital, Sydney, Australia
- Neuroscience Research Australia, Sydney, Australia
| | - Karl Ng
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Neurology Department, Royal North Shore Hospital, Sydney, Australia
| | - Ira W Deveson
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
| | - Marina L Kennerson
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- The Northcott Neuroscience Laboratory, ANZAC Research Institute, Sydney Local Health District, Sydney, Australia
| | - Kishore Raj Kumar
- Molecular Medicine Laboratory and Neurology Department, Concord Repatriation General Hospital, Sydney, Australia
- Faculty of Medicine and Health, The University of Sydney, Sydney, Australia
- Genomics and Inherited Disease Program, The Garvan Institute of Medical Research, Sydney, Australia
- Faculty of Medicine, University of New South Wales, Sydney, Australia
- Faculty of Medicine, St Vincent's Healthcare Campus, UNSW Sydney, Sydney, Australia
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Ransdell JL, Carrasquillo Y, Bosch MK, Mellor RL, Ornitz DM, Nerbonne JM. Loss of Intracellular Fibroblast Growth Factor 14 (iFGF14) Increases the Excitability of Mature Hippocampal and Cortical Pyramidal Neurons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.04.592532. [PMID: 38746081 PMCID: PMC11092765 DOI: 10.1101/2024.05.04.592532] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Mutations in FGF14 , which encodes intracellular fibroblast growth factor 14 (iFGF14), have been linked to spinocerebellar ataxia type 27 (SCA27), a multisystem disorder associated with progressive deficits in motor coordination and cognitive function. Mice ( Fgf14 -/- ) lacking iFGF14 display similar phenotypes, and we have previously shown that the deficits in motor coordination reflect reduced excitability of cerebellar Purkinje neurons, owing to the loss of iFGF14-mediated regulation of the voltage-dependence of inactivation of the fast transient component of the voltage-gated Na + (Nav) current, I NaT . Here, we present the results of experiments designed to test the hypothesis that loss of iFGF14 also attenuates the intrinsic excitability of mature hippocampal and cortical pyramidal neurons. Current-clamp recordings from adult mouse hippocampal CA1 pyramidal neurons in acute in vitro slices, however, revealed that repetitive firing rates were higher in Fgf14 -/- , than in wild type (WT), cells. In addition, the waveforms of individual action potentials were altered in Fgf14 -/- hippocampal CA1 pyramidal neurons, and the loss of iFGF14 reduced the time delay between the initiation of axonal and somal action potentials. Voltage-clamp recordings revealed that the loss of iFGF14 altered the voltage-dependence of activation, but not inactivation, of I NaT in CA1 pyramidal neurons. Similar effects of the loss of iFGF14 on firing properties were evident in current-clamp recordings from layer 5 visual cortical pyramidal neurons. Additional experiments demonstrated that the loss of iFGF14 does not alter the distribution of anti-Nav1.6 or anti-ankyrin G immunofluorescence labeling intensity along the axon initial segments (AIS) of mature hippocampal CA1 or layer 5 visual cortical pyramidal neurons in situ . Taken together, the results demonstrate that, in contrast with results reported for neonatal (rat) hippocampal pyramidal neurons in dissociated cell culture, the loss of iFGF14 does not disrupt AIS architecture or Nav1.6 localization/distribution along the AIS of mature hippocampal (or cortical) pyramidal neurons in situ .
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5
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Lin CYR, Kuo SH. Ataxias: Hereditary, Acquired, and Reversible Etiologies. Semin Neurol 2023; 43:48-64. [PMID: 36828010 DOI: 10.1055/s-0043-1763511] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/26/2023]
Abstract
A variety of etiologies can cause cerebellar dysfunction, leading to ataxia symptoms. Therefore, the accurate diagnosis of the cause for cerebellar ataxia can be challenging. A step-wise investigation will reveal underlying causes, including nutritional, toxin, immune-mediated, genetic, and degenerative disorders. Recent advances in genetics have identified new genes for both autosomal dominant and autosomal recessive ataxias, and new therapies are on the horizon for targeting specific biological pathways. New diagnostic criteria for degenerative ataxias have been proposed, specifically for multiple system atrophy, which will have a broad impact on the future clinical research in ataxia. In this article, we aim to provide a review focus on symptoms, laboratory testing, neuroimaging, and genetic testing for the diagnosis of cerebellar ataxia causes, with a special emphasis on recent advances. Strategies for the management of cerebellar ataxia is also discussed.
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Affiliation(s)
- Chi-Ying R Lin
- Department of Neurology, Parkinson's Disease Center and Movement Disorders Clinic, Baylor College of Medicine, Houston, Texas.,Department of Neurology, Alzheimer's Disease and Memory Disorders Center, Baylor College of Medicine, Houston, Texas
| | - Sheng-Han Kuo
- Department of Neurology, College of Physicians and Surgeons, Columbia University Irving Medical Center, New York, New York.,Initiative for Columbia Ataxia and Tremor, Columbia University Irving Medical Center, New York, New York
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Rafehi H, Read J, Szmulewicz DJ, Davies KC, Snell P, Fearnley LG, Scott L, Thomsen M, Gillies G, Pope K, Bennett MF, Munro JE, Ngo KJ, Chen L, Wallis MJ, Butler EG, Kumar KR, Wu KHC, Tomlinson SE, Tisch S, Malhotra A, Lee-Archer M, Dolzhenko E, Eberle MA, Roberts LJ, Fogel BL, Brüggemann N, Lohmann K, Delatycki MB, Bahlo M, Lockhart PJ. An intronic GAA repeat expansion in FGF14 causes the autosomal-dominant adult-onset ataxia SCA50/ATX-FGF14. Am J Hum Genet 2023; 110:105-119. [PMID: 36493768 PMCID: PMC9892775 DOI: 10.1016/j.ajhg.2022.11.015] [Citation(s) in RCA: 58] [Impact Index Per Article: 58.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Accepted: 11/19/2022] [Indexed: 12/13/2022] Open
Abstract
Adult-onset cerebellar ataxias are a group of neurodegenerative conditions that challenge both genetic discovery and molecular diagnosis. In this study, we identified an intronic (GAA) repeat expansion in fibroblast growth factor 14 (FGF14). Genetic analysis of 95 Australian individuals with adult-onset ataxia identified four (4.2%) with (GAA)>300 and a further nine individuals with (GAA)>250. PCR and long-read sequence analysis revealed these were pure (GAA) repeats. In comparison, no control subjects had (GAA)>300 and only 2/311 control individuals (0.6%) had a pure (GAA)>250. In a German validation cohort, 9/104 (8.7%) of affected individuals had (GAA)>335 and a further six had (GAA)>250, whereas 10/190 (5.3%) control subjects had (GAA)>250 but none were (GAA)>335. The combined data suggest (GAA)>335 are disease causing and fully penetrant (p = 6.0 × 10-8, OR = 72 [95% CI = 4.3-1,227]), while (GAA)>250 is likely pathogenic with reduced penetrance. Affected individuals had an adult-onset, slowly progressive cerebellar ataxia with variable features including vestibular impairment, hyper-reflexia, and autonomic dysfunction. A negative correlation between age at onset and repeat length was observed (R2 = 0.44, p = 0.00045, slope = -0.12) and identification of a shared haplotype in a minority of individuals suggests that the expansion can be inherited or generated de novo during meiotic division. This study demonstrates the power of genome sequencing and advanced bioinformatic tools to identify novel repeat expansions via model-free, genome-wide analysis and identifies SCA50/ATX-FGF14 as a frequent cause of adult-onset ataxia.
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Affiliation(s)
- Haloom Rafehi
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Justin Read
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia,Department of Paediatrics, University of Melbourne, Royal Children’s Hospital, Parkville, VIC, Australia
| | - David J. Szmulewicz
- Cerebellar Ataxia Clinic, Eye and Ear Hospital, Melbourne, VIC, Australia,The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Melbourne, VIC, Australia
| | - Kayli C. Davies
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia,Department of Paediatrics, University of Melbourne, Royal Children’s Hospital, Parkville, VIC, Australia
| | - Penny Snell
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia
| | - Liam G. Fearnley
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia,Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia
| | - Liam Scott
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia
| | - Mirja Thomsen
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Greta Gillies
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia
| | - Kate Pope
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia
| | - Mark F. Bennett
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia,Epilepsy Research Centre, Department of Medicine, University of Melbourne, Austin Health, Heidelberg, VIC, Australia
| | - Jacob E. Munro
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia,Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia
| | - Kathie J. Ngo
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Luke Chen
- Alfred Hospital, Department of Neurology, Melbourne, VIC, Australia
| | - Mathew J. Wallis
- Clinical Genetics Service, Austin Health, Melbourne, VIC, Australia,Department of Medicine, University of Melbourne, Austin Health, Melbourne, VIC, Australia,School of Medicine and Menzies Institute for Medical Research, University of Tasmania, Hobart, TAS, Australia
| | | | - Kishore R. Kumar
- Faculty of Medicine and Health, The University of Sydney, Sydney, NSW, Australia,Molecular Medicine Laboratory and Department of Neurology, Concord Repatriation General Hospital, Concord, NSW, Australia,Garvan Institute of Medical Research, Sydney, NSW, Australia
| | - Kathy HC. Wu
- School of Medicine, University of New South Wales, Sydney, NSW, Australia,Clinical Genomics, St Vincent’s Hospital, Darlinghurst, NSW, Australia,Discipline of Genomic Medicine, Faculty of Medicine and Health, University of Sydney, Sydney, NSW, Australia,School of Medicine, University of Notre Dame, Sydney, NSW, Australia
| | - Susan E. Tomlinson
- School of Medicine, University of Notre Dame, Sydney, NSW, Australia,Department of Neurology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Stephen Tisch
- School of Medicine, University of New South Wales, Sydney, NSW, Australia,Department of Neurology, St Vincent’s Hospital, Darlinghurst, NSW, Australia
| | - Abhishek Malhotra
- Department of Neuroscience, University Hospital Geelong, Geelong, VIC, Australia
| | - Matthew Lee-Archer
- Launceston General Hospital, Tasmanian Health Service, Launceston, TAS, Australia
| | | | | | - Leslie J. Roberts
- Department of Neurology and Neurological Research, St. Vincent’s Hospital, Melbourne, VIC, Australia
| | - Brent L. Fogel
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA,Departments of Human Genetics, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Los Angeles, CA, USA
| | - Norbert Brüggemann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany,Department of Neurology, University Medical Center Schleswig-Holstein, Campus Lübeck, Germany
| | - Katja Lohmann
- Institute of Neurogenetics, University of Lübeck, Lübeck, Germany
| | - Martin B. Delatycki
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia,Department of Paediatrics, University of Melbourne, Royal Children’s Hospital, Parkville, VIC, Australia,Victorian Clinical Genetics Services, Melbourne, VIC, Australia
| | - Melanie Bahlo
- Population Health and Immunity Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC, Australia.
| | - Paul J. Lockhart
- Bruce Lefroy Centre, Murdoch Children’s Research Institute, Parkville, VIC 3052, Australia,Department of Paediatrics, University of Melbourne, Royal Children’s Hospital, Parkville, VIC, Australia,Corresponding author
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Younger DS. Neurogenetic motor disorders. HANDBOOK OF CLINICAL NEUROLOGY 2023; 195:183-250. [PMID: 37562870 DOI: 10.1016/b978-0-323-98818-6.00003-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/12/2023]
Abstract
Advances in the field of neurogenetics have practical applications in rapid diagnosis on blood and body fluids to extract DNA, obviating the need for invasive investigations. The ability to obtain a presymptomatic diagnosis through genetic screening and biomarkers can be a guide to life-saving disease-modifying therapy or enzyme replacement therapy to compensate for the deficient disease-causing enzyme. The benefits of a comprehensive neurogenetic evaluation extend to family members in whom identification of the causal gene defect ensures carrier detection and at-risk counseling for future generations. This chapter explores the many facets of the neurogenetic evaluation in adult and pediatric motor disorders as a primer for later chapters in this volume and a roadmap for the future applications of genetics in neurology.
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Affiliation(s)
- David S Younger
- Department of Clinical Medicine and Neuroscience, CUNY School of Medicine, New York, NY, United States; Department of Medicine, Section of Internal Medicine and Neurology, White Plains Hospital, White Plains, NY, United States.
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Dvorak NM, Tapia CM, Singh AK, Baumgartner TJ, Wang P, Chen H, Wadsworth PA, Zhou J, Laezza F. Pharmacologically Targeting the Fibroblast Growth Factor 14 Interaction Site on the Voltage-Gated Na + Channel 1.6 Enables Isoform-Selective Modulation. Int J Mol Sci 2021; 22:ijms222413541. [PMID: 34948337 PMCID: PMC8708424 DOI: 10.3390/ijms222413541] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 12/15/2021] [Accepted: 12/15/2021] [Indexed: 01/05/2023] Open
Abstract
Voltage-gated Na+ (Nav) channels are the primary molecular determinant of the action potential. Among the nine isoforms of the Nav channel α subunit that have been described (Nav1.1-Nav1.9), Nav1.1, Nav1.2, and Nav1.6 are the primary isoforms expressed in the central nervous system (CNS). Crucially, these three CNS Nav channel isoforms display differential expression across neuronal cell types and diverge with respect to their subcellular distributions. Considering these differences in terms of their localization, the CNS Nav channel isoforms could represent promising targets for the development of targeted neuromodulators. However, current therapeutics that target Nav channels lack selectivity, which results in deleterious side effects due to modulation of off-target Nav channel isoforms. Among the structural components of the Nav channel α subunit that could be pharmacologically targeted to achieve isoform selectivity, the C-terminal domains (CTD) of Nav channels represent promising candidates on account of displaying appreciable amino acid sequence divergence that enables functionally unique protein–protein interactions (PPIs) with Nav channel auxiliary proteins. In medium spiny neurons (MSNs) of the nucleus accumbens (NAc), a critical brain region of the mesocorticolimbic circuit, the PPI between the CTD of the Nav1.6 channel and its auxiliary protein fibroblast growth factor 14 (FGF14) is central to the generation of electrical outputs, underscoring its potential value as a site for targeted neuromodulation. Focusing on this PPI, we previously developed a peptidomimetic derived from residues of FGF14 that have an interaction site on the CTD of the Nav1.6 channel. In this work, we show that whereas the compound displays dose-dependent effects on the activity of Nav1.6 channels in heterologous cells, the compound does not affect Nav1.1 or Nav1.2 channels at comparable concentrations. In addition, we show that the compound correspondingly modulates the action potential discharge and the transient Na+ of MSNs of the NAc. Overall, these results demonstrate that pharmacologically targeting the FGF14 interaction site on the CTD of the Nav1.6 channel is a strategy to achieve isoform-selective modulation, and, more broadly, that sites on the CTDs of Nav channels interacted with by auxiliary proteins could represent candidates for the development of targeted therapeutics.
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A Variation in FGF14 Is Associated with Downbeat Nystagmus in a Genome-Wide Association Study. THE CEREBELLUM 2021; 19:348-357. [PMID: 32157568 PMCID: PMC7198638 DOI: 10.1007/s12311-020-01113-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Downbeat nystagmus (DBN) is a frequent form of acquired persisting central fixation nystagmus, often associated with other cerebellar ocular signs, such as saccadic smooth pursuit or gaze-holding deficits. Despite its distinct clinical features, the underlying etiology of DBN often remains unclear. Therefore, a genome-wide association study (GWAS) was conducted in 106 patients and 2609 healthy controls of European ancestry to identify genetic variants associated with DBN. A genome-wide significant association (p < 5 × 10-8) with DBN was found for a variation on chromosome 13 located within the fibroblast growth factor 14 gene (FGF14). FGF14 is expressed in Purkinje cells (PCs) and a reduction leads to a decreased spontaneous firing rate and excitability of PCs, compatible with the pathophysiology of DBN. In addition, mutations in the FGF14 gene cause spinocerebellar ataxia type 27. Suggestive associations (p < 1 × 10-05) could be detected for 15 additional LD-independent loci, one of which is also located in the FGF14 gene. An association of a region containing the dihydrofolate reductase (DHFR) and MutS Homolog 3 (MSH3) genes on chromosome 5 was slightly below the genome-wide significance threshold. DHFR is relevant for neuronal regulation, and a dysfunction is known to induce cerebellar damage. Among the remaining twelve suggestive associations, four genes (MAST4, TPPP, FTMT, and IDS) seem to be involved in cerebral pathological processes. Thus, this GWAS analysis has identified a potential genetic contribution to idiopathic DBN, including suggestive associations to several genes involved in postulated pathological mechanisms of DBN (i.e., impaired function of cerebellar PCs).
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Shaikh AG, Manto M. Genome-Wide Association Study Points New Direction for Downbeat Nystagmus Research. THE CEREBELLUM 2020; 19:345-347. [PMID: 32253642 DOI: 10.1007/s12311-020-01128-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Aasef G Shaikh
- Neurological Institute, University Hospitals Cleveland, Cleveland, OH, USA. .,Department of Neurology, Case Western Reserve University, Cleveland, OH, USA. .,Department of Biomedical Engineering, Case Western Reserve University, Cleveland, OH, USA. .,Neurology Service and Daroff-Dell'Osso Ocular Motility Laboratory, Louis Stokes Cleveland Medical Center, Cleveland, OH, USA. .,Department of Neurology, University Hospitals Cleveland Medical Center, 11100 Euclid Avenue, Cleveland, OH, 44110, USA.
| | - Mario Manto
- Department of Neurology, CHU-Charleroi, Charleroi, Belgium.,University of Mons, Mons, Belgium
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11
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Paucar M, Lundin J, Alshammari T, Bergendal Å, Lindefeldt M, Alshammari M, Solders G, Di Re J, Savitcheva I, Granberg T, Laezza F, Iwarsson E, Svenningsson P. Broader phenotypic traits and widespread brain hypometabolism in spinocerebellar ataxia 27. J Intern Med 2020; 288:103-115. [PMID: 32112487 PMCID: PMC10123866 DOI: 10.1111/joim.13052] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVE The goal of this study was to characterize a Swedish family with members affected by spinocerebellar ataxia 27 (SCA27), a rare autosomal dominant disease caused by mutations in fibroblast growth factor 14 (FGF14). Despite normal structural neuroimaging, psychiatric manifestations and intellectual disability are part of the SCA27 phenotype raising the need for functional neuroimaging. Here, we used clinical assessments, structural and functional neuroimaging to characterize these new SCA27 patients. Since one patient presents with a psychotic disorder, an exploratory study of markers of schizophrenia associated with GABAergic neurotransmission was performed in fgf14-/- mice, a preclinical model that replicates motor and learning deficits of SCA27. METHODS A comprehensive characterization that included clinical assessments, cognitive tests, structural neuroimaging studies, brain metabolism with 18 F-fluorodeoxyglucose PET ([18F] FDG PET) and genetic analyses was performed. Brains of fgf14-/- mice were studied with immunohistochemistry. RESULTS Nine patients had ataxia, and all affected patients harboured an interstitial deletion of chromosome 13q33.1 encompassing the entire FGF14 and integrin subunit beta like 1 (ITGBL1) genes. New features for SCA27 were identified: congenital onset, psychosis, attention deficit hyperactivity disorder and widespread hypometabolism that affected the medial prefrontal cortex (mPFC) in all patients. Hypometabolism in the PFC was far more pronounced in a SCA27 patient with psychosis. Reduced expression of VGAT was found in the mPFC of fgf14-/- mice. CONCLUSIONS This is the second largest SCA27 family identified to date. We provide new clinical and preclinical evidence for a significant psychiatric component in SCA27, strengthening the hypothesis of FGF14 as an important modulator of psychiatric disease.
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Affiliation(s)
- M Paucar
- From the, Departments of, Department of, Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of, Neurology, Karolinska University Hospital, Stockholm, Sweden
| | - J Lundin
- Department of, Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - T Alshammari
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX, USA
- Department of, Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - Å Bergendal
- From the, Departments of, Department of, Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - M Lindefeldt
- Department of, Pediatric Neurology, Astrid Lindgren's Hospital, Stockholm, Sweden
| | - M Alshammari
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX, USA
- Department of, Pharmacology and Toxicology, College of Pharmacy, King Saud University, Riyadh, Saudi Arabia
| | - G Solders
- From the, Departments of, Department of, Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of, Neurophysiology, Karolinska University Hospital, Stockholm, Sweden
| | - J Di Re
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX, USA
- Neuroscience Graduate Program, The University of Texas Medical Branch, Galveston, TX, USA
| | - I Savitcheva
- Departments of, Department of, Nuclear Medicine, Karolinska University Hospital, Stockholm, Sweden
| | - T Granberg
- From the, Departments of, Department of, Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of, Radiology, Karolinska University Hospital, Stockholm, Sweden
| | - F Laezza
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Galveston, TX, USA
| | - E Iwarsson
- Department of, Molecular Medicine and Surgery, Karolinska Institutet, Stockholm, Sweden
| | - P Svenningsson
- From the, Departments of, Department of, Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of, Neurology, Karolinska University Hospital, Stockholm, Sweden
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12
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Lalonde R, Strazielle C. Motor Performances of Spontaneous and Genetically Modified Mutants with Cerebellar Atrophy. THE CEREBELLUM 2019; 18:615-634. [PMID: 30820866 DOI: 10.1007/s12311-019-01017-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Chance discovery of spontaneous mutants with atrophy of the cerebellar cortex has unearthed genes involved in optimizing motor coordination. Rotorod, stationary beam, and suspended wire tests are useful in delineating behavioral phenotypes of spontaneous mutants with cerebellar atrophy such as Grid2Lc, Grid2ho, Rorasg, Agtpbp1pcd, Relnrl, and Dab1scm. Likewise, transgenic or null mutants serving as experimental models of spinocerebellar ataxia (SCA) are phenotyped with the same tests. Among experimental models of autosomal dominant SCA, rotorod deficits were reported in SCA1 to 3, SCA5 to 8, SCA14, SCA17, and SCA27 and stationary beam deficits in SCA1 to 3, SCA5, SCA6, SCA13, SCA17, and SCA27. Beam tests are sensitive to experimental therapies of various kinds including molecules affecting glutamate signaling, mesenchymal stem cells, anti-oligomer antibodies, lentiviral vectors carrying genes, interfering RNAs, or neurotrophic factors, and interbreeding with other mutants.
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Affiliation(s)
- Robert Lalonde
- Department of Psychology, University of Rouen, 76821, Mont-Saint-Aignan Cedex, France.
| | - Catherine Strazielle
- Laboratory of Stress, Immunity, and Pathogens EA7300, and CHRU of Nancy, University of Lorraine, 54500, Vandoeuvre-les-Nancy, France
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13
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Schesny M, Joncourt F, Tarnutzer AA. Acetazolamide-Responsive Episodic Ataxia Linked to Novel Splice Site Variant in FGF14 Gene. THE CEREBELLUM 2019; 18:649-653. [PMID: 30607796 DOI: 10.1007/s12311-018-0997-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Here we describe the case of a patient with episodic dizziness and gait imbalance for 7 years and a negative family history. On clinical examination, interictally, the patient presented with gaze-evoked nystagmus and rebound nystagmus and slight dysarthria. MRI of the brain was normal and peripheral-vestibular function was bilaterally intact. Based on genetic testing (episodic ataxia panel), a heterozygote splice site variant in intron 1 of the FGF14 gene was identified. This report adds important new evidence to previous observations that pathogenic variants in the FGF14 gene may result in variable phenotypes, either in progressive spinocerebellar ataxia (type 27) or in episodic ataxia as in our case. Our patient responded well to acetazolamide (reduction in the frequency of attacks by about two thirds), supporting the hypothesis of a sodium channelopathy.
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Affiliation(s)
- M Schesny
- Department of Neurology, University Hospital Zurich, Frauenklinikstr. 26, 8091, Zurich, Switzerland
| | - F Joncourt
- Division of Human Genetics, Department of Pediatrics, University Hospital Berne, Berne, Switzerland
| | - Alexander A Tarnutzer
- Department of Neurology, University Hospital Zurich, Frauenklinikstr. 26, 8091, Zurich, Switzerland. .,University of Zurich, Zurich, Switzerland.
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14
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Factors other than hTau overexpression that contribute to tauopathy-like phenotype in rTg4510 mice. Nat Commun 2019; 10:2479. [PMID: 31171783 PMCID: PMC6554306 DOI: 10.1038/s41467-019-10428-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 05/10/2019] [Indexed: 12/17/2022] Open
Abstract
The tauopathy-like phenotype observed in the rTg4510 mouse line, in which human tauP301L expression specifically within the forebrain can be temporally controlled, has largely been attributed to high overexpression of mutant human tau in the forebrain region. Unexpectedly, we found that in a different mouse line with a targeted-insertion of the same transgene driven by the same tetracycline-TransActivator (tTA) allele, but with even higher overexpression of tauP301L than rTg4510, atrophy and tau histopathology are delayed, and a different behavioral profile is observed. This suggests that it is not overexpression of mutant human tau alone that contributes to the phenotype in rTg4510 mice. Furthermore we show that the tauopathy-like phenotype seen in rTg4510 requires a ~70-copy tau-transgene insertion in a 244 kb deletion in Fgf14, a ~7-copy tTA-transgene insertion in a 508 kb deletion that disrupts another five genes, in addition to high transgene overexpression. We propose that these additional effects need to be accounted for in any studies using rTg4510.
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15
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Miura S, Kosaka K, Fujioka R, Uchiyama Y, Shimojo T, Morikawa T, Irie A, Taniwaki T, Shibata H. Spinocerebellar ataxia 27 with a novel nonsense variant (Lys177X) in FGF14. Eur J Med Genet 2019; 62:172-176. [DOI: 10.1016/j.ejmg.2018.07.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 07/09/2018] [Indexed: 12/22/2022]
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Groth CL, Berman BD. Spinocerebellar Ataxia 27: A Review and Characterization of an Evolving Phenotype. Tremor Other Hyperkinet Mov (N Y) 2018; 8:534. [PMID: 29416937 PMCID: PMC5801325 DOI: 10.7916/d80s0zjq] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 01/08/2018] [Indexed: 12/23/2022] Open
Abstract
Background Spinocerebellar ataxia (SCA) is an uncommon form of progressive cerebellar ataxia with multiple genetic causes and marked variability in phenotypic expression even across patients with identical genetic abnormalities. SCA27 is a recently identified SCA caused by mutations in the Fibroblast Growth Factor 14 gene, with a phenotypic expression that is only beginning to be fully appreciated. We report here a case of a 70-year-old male who presented with slowly worsening tremor and gait instability that began in his early adulthood along with additional features of parkinsonism on examination. Work-up revealed a novel pathogenic mutation in the Fibroblast Growth Factor 14 gene, and symptoms improved with amantadine and levodopa. We also provide a review of the literature in order to better characterize the phenotypic expression of this uncommon condition. Methods Case report and review of the literature. Results Review of the literature revealed a total of 32 previously reported clinical cases of SCA27. Including our case, we found that early-onset tremor (12.1 ± 10.5 years) was present in 95.8%, while gait ataxia tended to present later in life (23.7 ± 16.7 years) and was accompanied by limb ataxia, dysarthria, and nystagmus. Other features of SCA27 that may distinguish it from other SCAs include the potential for episodic ataxia, accompanying psychiatric symptoms, and cognitive impairment. Discussion Testing for SCA27 should be considered in individuals with ataxia who report tremor as an initial or early symptom, as well as those with additional findings of episodic ataxia, neuropsychiatric symptoms, or parkinsonism.
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Affiliation(s)
- Christopher L. Groth
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Brian D. Berman
- Department of Neurology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
- Neurology Section, Denver VA Medical Center, Denver, CO, USA
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17
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Familial episodic ataxia in lambs is potentially associated with a mutation in the fibroblast growth factor 14 (FGF14) gene. PLoS One 2017; 12:e0190030. [PMID: 29253853 PMCID: PMC5734737 DOI: 10.1371/journal.pone.0190030] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2017] [Accepted: 12/06/2017] [Indexed: 01/08/2023] Open
Abstract
Familial episodic ataxia of lambs is a congenital transient autosomal dominant disorder of newborn lambs, with varying expressivity. Affected lambs show episodes of an asymmetric ataxic gait, base-wide extensor hypertonia of the thoracic limbs and flexor hypertonia of the pelvic limbs. The aim of the study was to determine the genetic variant causing familial episodic ataxia in lambs. Using whole genome sequencing of two half-sib affected lambs, their sire, and their two normal dams, a heterozygous C>T transition at OAR10:77593415 (Oar_v3.1) in exon 1 of the fibroblast growth factor 14 (FGF14) gene (c.46C>T) was identified. The c.46C>T transition resulted in a premature stop codon at position 16 of the 247 amino acid FGF14 protein (p.Q16*). PCR and Sanger sequencing was used to genotype an additional 20 clinically affected animals, demonstrating all lambs carried the c.46C>T variant but 1 clinically more severely affected inbred lamb was homozygous (TT). A further 11 unrelated normal ewes were positionally sequenced, none of which had the variant, while in 18 lambs of unknown status born over 2 years of breeding trials six lambs were found to have the c.46C>T variant, likely clinically unidentified heterozygotes due to the variable expressivity, while 12 did not. In conclusion, familial episodic ataxia of lambs is potentially associated with a c.46C>T variant in the FGF14 gene. Further research is required into the mechanism behind the apparent recovery of lambs.
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18
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Abstract
The vertebrate endoskeleton is not a mere frame for muscle attachment to facilitate locomotion, but is a massive organ integrated with many physiologic functions including mineral and energy metabolism. Mineral balance is maintained by tightly controlled ion fluxes that are external (intestine and kidney) and internal (between bone and other organs), and are regulated and coordinated by many endocrine signals between these organs. The endocrine fibroblast growth factors (FGFs) and Klotho gene families are complex systems that co-evolved with the endoskeleton. In particular, FGF23 and αKlotho which are primarily derived from bone and kidney respectively, are critical in maintaining mineral metabolism where each of these proteins serving highly diverse roles; abound with many unanswered questions regarding their upstream regulation and downstream functions. Genetic lesions of components of this network produce discreet disturbances in many facets of mineral metabolism. One acquired condition with colossal elevations of FGF23 and suppression of αKlotho is chronic kidney disease where multiple organ dysfunction contributes to the morbidity and mortality. However, the single most important group of derangements that encompasses the largest breadth of complications is mineral metabolism disorders. Mineral metabolic disorders in CKD impact negatively and significantly on the progression of renal disease as well as extra-renal complications. Knowledge of the origin, nature, and impact of phosphate, FGF23, and αKlotho derangements is pivotal to understanding the pathophysiology and treatment of CKD.
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Affiliation(s)
- Makoto Kuro-O
- Center for Molecular Medicine, Jichi Medical University, Tochigi, Japan; Department of Pathology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Orson W Moe
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Charles and Jane Pak Center of Mineral Metabolism and Clinical Research, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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19
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Bosch MK, Nerbonne JM, Townsend RR, Miyazaki H, Nukina N, Ornitz DM, Marionneau C. Proteomic analysis of native cerebellar iFGF14 complexes. Channels (Austin) 2016; 10:297-312. [PMID: 26889602 DOI: 10.1080/19336950.2016.1153203] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Intracellular Fibroblast Growth Factor 14 (iFGF14) and the other intracellular FGFs (iFGF11-13) regulate the properties and densities of voltage-gated neuronal and cardiac Na(+) (Nav) channels. Recent studies have demonstrated that the iFGFs can also regulate native voltage-gated Ca(2+) (Cav) channels. In the present study, a mass spectrometry (MS)-based proteomic approach was used to identify the components of native cerebellar iFGF14 complexes. Using an anti-iFGF14 antibody, native iFGF14 complexes were immunoprecipitated from wild type adult mouse cerebellum. Parallel control experiments were performed on cerebellar proteins isolated from mice (Fgf14(-/-)) harboring a targeted disruption of the Fgf14 locus. MS analyses of immunoprecipitated proteins demonstrated that the vast majority of proteins identified in native cerebellar iFGF14 complexes are Nav channel pore-forming (α) subunits or proteins previously reported to interact with Nav α subunits. In contrast, no Cav channel α or accessory subunits were revealed in cerebellar iFGF14 immunoprecipitates. Additional experiments were completed using an anti-PanNav antibody to immunoprecipitate Nav channel complexes from wild type and Fgf14(-/-) mouse cerebellum. Western blot and MS analyses revealed that the loss of iFGF14 does not measurably affect the protein composition or the relative abundance of Nav channel interacting proteins in native adult mouse cerebellar Nav channel complexes.
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Affiliation(s)
- Marie K Bosch
- a Department of Developmental Biology , Washington University School of Medicine , St. Louis , MO , USA
| | - Jeanne M Nerbonne
- a Department of Developmental Biology , Washington University School of Medicine , St. Louis , MO , USA.,b Internal Medicine, Washington University School of Medicine , St. Louis , MO , USA
| | - R Reid Townsend
- b Internal Medicine, Washington University School of Medicine , St. Louis , MO , USA.,c Cell Biology & Physiology, Washington University School of Medicine , St. Louis , MO , USA
| | - Haruko Miyazaki
- d Laboratory of Structural Pathology, Doshisha University, Kyotanabe-shi, Kyoto , Japan
| | - Nobuyuki Nukina
- d Laboratory of Structural Pathology, Doshisha University, Kyotanabe-shi, Kyoto , Japan
| | - David M Ornitz
- a Department of Developmental Biology , Washington University School of Medicine , St. Louis , MO , USA
| | - Céline Marionneau
- e L'Institut du Thorax, INSERM UMR1087, CNRS UMR6291, Université de Nantes , Nantes , France
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20
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Alshammari MA, Alshammari TK, Nenov MN, Scala F, Laezza F. Fibroblast Growth Factor 14 Modulates the Neurogenesis of Granule Neurons in the Adult Dentate Gyrus. Mol Neurobiol 2015; 53:7254-7270. [PMID: 26687232 DOI: 10.1007/s12035-015-9568-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Accepted: 11/29/2015] [Indexed: 11/25/2022]
Abstract
Adult neurogenesis, the production of mature neurons from progenitor cells in the adult mammalian brain, is linked to the etiology of neurodegenerative and psychiatric disorders. However, a thorough understanding of the molecular elements at the base of adult neurogenesis remains elusive. Here, we provide evidence for a previously undescribed function of fibroblast growth factor 14 (FGF14), a brain disease-associated factor that controls neuronal excitability and synaptic plasticity, in regulating adult neurogenesis in the dentate gyrus (DG). We found that FGF14 is dynamically expressed in restricted subtypes of sex determining region Y-box 2 (Sox2)-positive and doublecortin (DCX)-positive neural progenitors in the DG. Bromodeoxyuridine (BrdU) incorporation studies and confocal imaging revealed that genetic deletion of Fgf14 in Fgf14 -/- mice leads to a significant change in the proportion of proliferating and immature and mature newly born adult granule cells. This results in an increase in the late immature and early mature population of DCX and calretinin (CR)-positive neurons. Electrophysiological extracellular field recordings showed reduced minimal threshold response and impaired paired-pulse facilitation at the perforant path to DG inputs in Fgf14 -/- compared to Fgf14 +/+ mice, supporting disrupted synaptic connectivity as a correlative read-out to impaired neurogenesis. These new insights into the biology of FGF14 in neurogenesis shed light into the signaling pathways associated with disrupted functions in complex brain diseases.
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Affiliation(s)
- Musaad A Alshammari
- Pharmacology and Toxicology Graduate Program, The University of Texas Medical Branch, Galveston, TX, USA
- Graduate Studies Abroad Program, King Saud University, Riyadh, Saudi Arabia
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Tahani K Alshammari
- Pharmacology and Toxicology Graduate Program, The University of Texas Medical Branch, Galveston, TX, USA
- Graduate Studies Abroad Program, King Saud University, Riyadh, Saudi Arabia
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Miroslav N Nenov
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Federico Scala
- Biophysics Graduate Program, Institute of Human Physiology, Università Cattolica, Rome, Italy
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA
| | - Fernanda Laezza
- Mitchell Center for Neurodegenerative Diseases, The University of Texas Medical Branch, Galveston, TX, USA.
- Center for Addiction Research, The University of Texas Medical Branch, Galveston, TX, USA.
- Center for Biomedical Engineering, The University of Texas Medical Branch, Galveston, TX, USA.
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, Medical Research Building 7.102B, 301 University Boulevard, Galveston, TX, 77555, USA.
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Intracellular FGF14 (iFGF14) Is Required for Spontaneous and Evoked Firing in Cerebellar Purkinje Neurons and for Motor Coordination and Balance. J Neurosci 2015; 35:6752-69. [PMID: 25926453 DOI: 10.1523/jneurosci.2663-14.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Mutations in FGF14, which encodes intracellular fibroblast growth factor 14 (iFGF14), have been linked to spinocerebellar ataxia (SCA27). In addition, mice lacking Fgf14 (Fgf14(-/-)) exhibit an ataxia phenotype resembling SCA27, accompanied by marked changes in the excitability of cerebellar granule and Purkinje neurons. It is not known, however, whether these phenotypes result from defects in neuronal development or if they reflect a physiological requirement for iFGF14 in the adult cerebellum. Here, we demonstrate that the acute and selective Fgf14-targeted short hairpin RNA (shRNA)-mediated in vivo "knock-down" of iFGF14 in adult Purkinje neurons attenuates spontaneous and evoked action potential firing without measurably affecting the expression or localization of voltage-gated Na(+) (Nav) channels at Purkinje neuron axon initial segments. The selective shRNA-mediated in vivo "knock-down" of iFGF14 in adult Purkinje neurons also impairs motor coordination and balance. Repetitive firing can be restored in Fgf14-targeted shRNA-expressing Purkinje neurons, as well as in Fgf14(-/-) Purkinje neurons, by prior membrane hyperpolarization, suggesting that the iFGF14-mediated regulation of the excitability of mature Purkinje neurons depends on membrane potential. Further experiments revealed that the loss of iFGF14 results in a marked hyperpolarizing shift in the voltage dependence of steady-state inactivation of the Nav currents in adult Purkinje neurons. We also show here that expressing iFGF14 selectively in adult Fgf14(-/-) Purkinje neurons rescues spontaneous firing and improves motor performance. Together, these results demonstrate that iFGF14 is required for spontaneous and evoked action potential firing in adult Purkinje neurons, thereby controlling the output of these cells and the regulation of motor coordination and balance.
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Tempia F, Hoxha E, Negro G, Alshammari MA, Alshammari TK, Panova-Elektronova N, Laezza F. Parallel fiber to Purkinje cell synaptic impairment in a mouse model of spinocerebellar ataxia type 27. Front Cell Neurosci 2015; 9:205. [PMID: 26089778 PMCID: PMC4455242 DOI: 10.3389/fncel.2015.00205] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 05/11/2015] [Indexed: 11/13/2022] Open
Abstract
Genetically inherited mutations in the fibroblast growth factor 14 (FGF14) gene lead to spinocerebellar ataxia type 27 (SCA27), an autosomal dominant disorder characterized by heterogeneous motor and cognitive impairments. Consistently, genetic deletion of Fgf14 in Fgf14 (-/-) mice recapitulates salient features of the SCA27 human disease. In vitro molecular studies in cultured neurons indicate that the FGF14 (F145S) SCA27 allele acts as a dominant negative mutant suppressing the FGF14 wild type function and resulting in inhibition of voltage-gated Na(+) and Ca(2+) channels. To gain insights in the cerebellar deficits in the animal model of the human disease, we applied whole-cell voltage-clamp in the acute cerebellar slice preparation to examine the properties of parallel fibers (PF) to Purkinje neuron synapses in Fgf14 (-/-) mice and wild type littermates. We found that the AMPA receptor-mediated excitatory postsynaptic currents evoked by PF stimulation (PF-EPSCs) were significantly reduced in Fgf14 (-/-) animals, while short-term plasticity, measured as paired-pulse facilitation (PPF), was enhanced. Measuring Sr(2+)-induced release of quanta from stimulated synapses, we found that the size of the PF-EPSCs was unchanged, ruling out a postsynaptic deficit. This phenotype was corroborated by decreased expression of VGLUT1, a specific presynaptic marker at PF-Purkinje neuron synapses. We next examined the mGluR1 receptor-induced response (mGluR1-EPSC) that under normal conditions requires a gradual build-up of glutamate concentration in the synaptic cleft, and found no changes in these responses in Fgf14 (-/-) mice. These results provide evidence of a critical role of FGF14 in maintaining presynaptic function at PF-Purkinje neuron synapses highlighting critical target mechanisms to recapitulate the complexity of the SCA27 disease.
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Affiliation(s)
- Filippo Tempia
- Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA ; Department of Neuroscience, University of Torino Torino, Italy ; Neuroscience Institute Cavalieri Ottolenghi Torino, Italy ; National Institute of Neuroscience-Torino Italy
| | - Eriola Hoxha
- Department of Neuroscience, University of Torino Torino, Italy ; Neuroscience Institute Cavalieri Ottolenghi Torino, Italy
| | - Giulia Negro
- Neuroscience Institute Cavalieri Ottolenghi Torino, Italy
| | - Musaad A Alshammari
- Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA ; Pharmacology and Toxicology Graduate Program, University of Texas Medical Branch Galveston, Texas, USA ; King Saud University Graduate Studies Abroad Program Riyadh, Saudi Arabia
| | - Tahani K Alshammari
- Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA ; Pharmacology and Toxicology Graduate Program, University of Texas Medical Branch Galveston, Texas, USA ; King Saud University Graduate Studies Abroad Program Riyadh, Saudi Arabia
| | - Neli Panova-Elektronova
- Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA
| | - Fernanda Laezza
- Department of Pharmacology and Toxicology, University of Texas Medical Branch Galveston, TX, USA ; Mitchell Center for Neurodegenerative Diseases, University of Texas Medical Branch Galveston, TX, USA ; Center for Addiction Research, University of Texas Medical Branch Galveston, TX, USA ; Center for Biomedical Engineering, University of Texas Medical Branch Galveston, TX, USA
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23
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Ornitz DM, Itoh N. The Fibroblast Growth Factor signaling pathway. WILEY INTERDISCIPLINARY REVIEWS. DEVELOPMENTAL BIOLOGY 2015; 4:215-66. [PMID: 25772309 PMCID: PMC4393358 DOI: 10.1002/wdev.176] [Citation(s) in RCA: 1337] [Impact Index Per Article: 148.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Revised: 11/23/2014] [Accepted: 01/08/2015] [Indexed: 12/13/2022]
Abstract
The signaling component of the mammalian Fibroblast Growth Factor (FGF) family is comprised of eighteen secreted proteins that interact with four signaling tyrosine kinase FGF receptors (FGFRs). Interaction of FGF ligands with their signaling receptors is regulated by protein or proteoglycan cofactors and by extracellular binding proteins. Activated FGFRs phosphorylate specific tyrosine residues that mediate interaction with cytosolic adaptor proteins and the RAS-MAPK, PI3K-AKT, PLCγ, and STAT intracellular signaling pathways. Four structurally related intracellular non-signaling FGFs interact with and regulate the family of voltage gated sodium channels. Members of the FGF family function in the earliest stages of embryonic development and during organogenesis to maintain progenitor cells and mediate their growth, differentiation, survival, and patterning. FGFs also have roles in adult tissues where they mediate metabolic functions, tissue repair, and regeneration, often by reactivating developmental signaling pathways. Consistent with the presence of FGFs in almost all tissues and organs, aberrant activity of the pathway is associated with developmental defects that disrupt organogenesis, impair the response to injury, and result in metabolic disorders, and cancer. For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- David M Ornitz
- Department of Developmental Biology, Washington University School of MedicineSt. Louis, MO, USA
- *
Correspondence to:
| | - Nobuyuki Itoh
- Graduate School of Pharmaceutical Sciences, Kyoto UniversitySakyo, Kyoto, Japan
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Planes M, Rooryck C, Vuillaume ML, Besnard L, Bouron J, Lacombe D, Arveiler B, Goizet C. SCA27 is a cause of early-onset ataxia and developmental delay. Eur J Paediatr Neurol 2015; 19:271-3. [PMID: 25530029 DOI: 10.1016/j.ejpn.2014.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/26/2014] [Accepted: 11/28/2014] [Indexed: 01/24/2023]
Affiliation(s)
- Marc Planes
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France.
| | - Caroline Rooryck
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France; Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576 Bordeaux, France
| | - Marie-Laure Vuillaume
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France; Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576 Bordeaux, France
| | - Lucie Besnard
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Julie Bouron
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France
| | - Didier Lacombe
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France; Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576 Bordeaux, France
| | - Benoit Arveiler
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France; Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576 Bordeaux, France
| | - Cyril Goizet
- CHU Bordeaux, Service de Génétique Médicale, Bordeaux, France; Univ. Bordeaux, Maladies Rares: Génétique et Métabolisme (MRGM), EA 4576 Bordeaux, France
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Choquet K, La Piana R, Brais B. A novel frameshift mutation in FGF14 causes an autosomal dominant episodic ataxia. Neurogenetics 2015; 16:233-6. [PMID: 25566820 DOI: 10.1007/s10048-014-0436-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 12/19/2014] [Indexed: 12/30/2022]
Abstract
Episodic ataxias (EAs) are a heterogeneous group of neurological disorders characterized by recurrent attacks of ataxia. Mutations in KCNA1 and CACNA1A account for the majority of EA cases worldwide. We recruited a two-generation family affected with EA of unknown subtype and performed whole-exome sequencing on two affected members. This revealed a novel heterozygous mutation c.211_212insA (p.I71NfsX27) leading to a premature stop codon in FGF14. Mutations in FGF14 are known to cause spinocerebellar ataxia type 27 (SCA27). Sanger sequencing confirmed segregation within the family. Our findings expand the phenotypic spectrum of SCA27 by underlining the possible episodic nature of this ataxia.
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Affiliation(s)
- Karine Choquet
- Neurogenetics of Motion Laboratory, Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada
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Bosch MK, Nerbonne JM, Ornitz DM. Dual transgene expression in murine cerebellar Purkinje neurons by viral transduction in vivo. PLoS One 2014; 9:e104062. [PMID: 25093726 PMCID: PMC4122438 DOI: 10.1371/journal.pone.0104062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 07/08/2014] [Indexed: 12/19/2022] Open
Abstract
Viral-vector mediated gene transfer to cerebellar Purkinje neurons in vivo is a promising avenue for gene therapy of cerebellar ataxias and for genetic manipulation in functional studies of animal models of cerebellar disease. Here, we report the results of experiments designed to identify efficient methods for viral transduction of adult murine Purkinje neurons in vivo. For these analyses, several lentiviral and an adeno-associated virus (AAV), serotype 1, vector with various promoter combinations were generated and compared for in situ transduction efficiency, assayed by fluorescent reporter protein expression in Purkinje neurons. Additional experiments were also conducted to identify the optimal experimental strategy for co-expression of two proteins in individual Purkinje neurons. Of the viruses tested, AAV1 with a CAG promoter exhibited the highest specificity for Purkinje neurons. To deliver two proteins to the same Purkinje neuron, several methods were tested, including: an internal ribosome entry site (IRES), a 2A sequence, a dual promoter vector, and co-injection of two viruses. Efficient expression of both proteins in the same Purkinje neuron was only achieved by co-injecting two AAV1-CAG viruses. We found that use of an AAV1-CAG virus outperformed similar lentivirus vectors and that co-injection of two AAV1-CAG viruses could be used to efficiently deliver two proteins to the same Purkinje neuron in adult mice. AAV1 with a CAG promoter is highly efficient and selective at transducing adult cerebellar Purkinje neurons and two AAV-CAG viruses can be used to efficiently express two proteins in the same neuron in vivo.
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Affiliation(s)
- Marie K. Bosch
- Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - Jeanne M. Nerbonne
- Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- Internal Medicine, Washington University School of Medicine, Saint Louis, Missouri, United States of America
| | - David M. Ornitz
- Developmental Biology, Washington University School of Medicine, Saint Louis, Missouri, United States of America
- * E-mail:
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Xiao M, Bosch MK, Nerbonne JM, Ornitz DM. FGF14 localization and organization of the axon initial segment. Mol Cell Neurosci 2013; 56:393-403. [PMID: 23891806 DOI: 10.1016/j.mcn.2013.07.008] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 06/26/2013] [Accepted: 07/21/2013] [Indexed: 01/26/2023] Open
Abstract
The axon initial segment (AIS) is highly enriched in the structural proteins ankyrin G and βIV-spectrin, the pore-forming (α) subunits of voltage-gated sodium (Nav) channels, and functional Nav channels, and is critical for the initiation of action potentials. We previously reported that FGF14, a member of the intracellular FGF (iFGF) sub-family, is expressed in cerebellar Purkinje neurons and that the targeted inactivation of Fgf14 in mice (Fgf14(-/-)) results in markedly reduced Purkinje neuron excitability. Here, we demonstrate that FGF14 immunoreactivity is high in the AIS of Purkinje neurons and is distributed in a decreasing, proximal to distal, gradient. This pattern is evident early in the postnatal development of Purkinje neurons and is also observed in many other types of central neurons. In (Scn8a(med)) mice, which are deficient in expression of the Nav1.6 α subunit, FGF14 immunoreactivity is markedly increased and expanded in the Purkinje neuron AIS, in parallel with increased expression of the Nav1.1 (Scn1a) α subunit and expanded expression of βIV-spectrin. Although Nav1.1, FGF14, and βIV-spectrin are affected, ankyrin G immunoreactivity at the AIS of Scn8a(med) and wild type (WT) Purkinje neurons was not significantly different. In Fgf14(-/-) Purkinje neurons, βIV-spectrin and ankyrin G immunoreactivity at the AIS were also similar to WT Purkinje neurons, although both the Nav1.1 and Nav1.6 α subunits are modestly, but significantly (p<0.005), reduced within sub-domains of the AIS, changes that may contribute to the reduced excitability of Fgf14(-/-) Purkinje neurons.
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Affiliation(s)
- Maolei Xiao
- Department of Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Yan H, Pablo JL, Pitt GS. FGF14 regulates presynaptic Ca2+ channels and synaptic transmission. Cell Rep 2013; 4:66-75. [PMID: 23831029 DOI: 10.1016/j.celrep.2013.06.012] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 05/13/2013] [Accepted: 06/07/2013] [Indexed: 10/26/2022] Open
Abstract
Fibroblast growth factor homologous factors (FHFs) are not growth factors, but instead bind to voltage-gated Na+ channels (NaV) and regulate their function. Mutations in FGF14, an FHF that is the locus for spinocerebellar ataxia 27 (SCA27), are believed to be pathogenic because of a dominant-negative reduction of NaV currents in cerebellar granule cells. Here, we demonstrate that FGF14 also regulates members of the presynaptic CaV2 Ca2+ channel family. Knockdown of FGF14 in granule cells reduced Ca2+ currents and diminished vesicular recycling, a marker for presynaptic Ca2+ influx. As a consequence, excitatory postsynaptic currents (EPSCs) at the granule cell to Purkinje cell synapse were markedly diminished. Expression of the SCA27-causing FGF14 mutant in granule cells exerted a dominant-negative reduction in Ca2+ currents, vesicular recycling, and the resultant EPSCs in Purkinje cells. Thus, FHFs are multimodal, regulating several discrete neuronal signaling events. SCA27 most likely results at least in part from dysregulation of Ca2+ channel function.
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Affiliation(s)
- Haidun Yan
- Division of Cardiology, Department of Medicine, Duke University Medical Center, Durham, NC 27710, USA
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Abstract
The hereditary cerebellar ataxias are a clinically and genetically heterogeneous group of disorders that primarily affect the cerebellum; often there are additional features such as neuropathy, cognitive decline, or maculopathy that help define the clinical subtype of ataxia. They are commonly classified according to their mode of inheritance into autosomal dominant, autosomal recessive, X-linked, and mitochondrial forms. Great advances have been made in understanding the genetics of cerebellar ataxias in the last 15 years. At least 36 different forms of ADCA are known, 20 autosomal-recessive, two X-linked, and several forms of ataxia associated with mitochondrial defects are known to date. However, in about 40 % of suspected genetically determined ataxia cases, the underlying genetic defect remains undetermined. Although the majority of disease genes have been found in the last two decades, over the last 2 years the genetics has undergone a methodological revolution. New DNA sequencing technologies are enabling us to investigate the whole or large targeted proportions of the genome in a rapid, affordable, and comprehensive way. Exome and targeted sequencing has recently identified four new genes causing ataxia: TGM6, ANO10, SYT14, and rundataxin. This approach is likely to continue to discover new ataxia genes and make screening of existing genes more effective. Translating the genetic findings into isolated and overlapping disease pathways will help stratify patient groups and identify therapeutic targets for ataxia that have so far remained undiscovered.
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Affiliation(s)
- Anna Sailer
- Department of Molecular Neuroscience, Institute of Neurology, Queen Square, London WC1N 3BG, United Kingdom
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The spinocerebellar ataxias: clinical aspects and molecular genetics. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 724:351-74. [PMID: 22411256 DOI: 10.1007/978-1-4614-0653-2_27] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Spinocerebellar ataxias (SCAs) are a highly heterogeneous group of inherited neurological disorders, based on clinical characterization alone with variable degrees of cerebellar ataxia often accompanied by additional cerebellar and noncerebellar symptoms which in most cases defy differentiation. Molecular causative deficits in at least 31 genes underlie the clinical symptoms in the SCAs by triggering cerebellar and, very frequently, brain stem dysfunction. The identification of the causative molecular deficits enables the molecular diagnosis of the different SCA subtypes and facilitates genetic counselling. Recent scientific advances are shedding light into developing therapeutic strategies. The scope of this chapter is to provide updated details of the spinocerebellar ataxias with particular emphasis on those aspects aimed at facilitating the clinical and genetic diagnoses.
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Shimojima K, Okumura A, Natsume J, Aiba K, Kurahashi H, Kubota T, Yokochi K, Yamamoto T. Spinocerebellar ataxias type 27 derived from a disruption of the fibroblast growth factor 14 gene with mimicking phenotype of paroxysmal non-kinesigenic dyskinesia. Brain Dev 2012; 34:230-3. [PMID: 21600715 DOI: 10.1016/j.braindev.2011.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 04/27/2011] [Accepted: 04/27/2011] [Indexed: 11/24/2022]
Abstract
Many types of spinocerebellar ataxias (SCAs) manifest as progressive disorders with cerebellar involvement. SCA type 27 (SCA27) is a rare type of SCA caused by mutations in the fibroblast growth factor 14 gene (FGF14). FGF14 disruption caused by a de novo reciprocal chromosomal translocation between chromosomes 13 and 21 was identified in a patient with the phenotype of paroxysmal non-kinesigenic dyskinesia (PNKD). This indicated genetic heterogeneity of PNKD, since 60% of the patients with PNKD exhibit mutations in another gene responsible for PNKD, the myofibrillogenesis regulator 1 gene (MR-1). We hypothesized that the remaining 40% of patients with PNKD may have FGF14 mutations; therefore, the nucleotide sequences of MR-1 and FGF14 were analyzed in another six patients with PNKD, but no nucleotide alterations were observed in these genes for these patients. Further studies should be conducted on the phenotypic heterogeneity of FGF14 mutations and/or haploinsufficiency in SCA27 and PNKD.
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Affiliation(s)
- Keiko Shimojima
- Tokyo Women's Medical University Institute for Integrated Medical Sciences, Shinjuku-ward, Tokyo, Japan
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Affiliation(s)
- Leslie J Cloud
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
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Wang C, Hennessey JA, Kirkton RD, Wang C, Graham V, Puranam RS, Rosenberg PB, Bursac N, Pitt GS. Fibroblast growth factor homologous factor 13 regulates Na+ channels and conduction velocity in murine hearts. Circ Res 2011; 109:775-82. [PMID: 21817159 DOI: 10.1161/circresaha.111.247957] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Fibroblast growth factor homologous factors (FHFs), a subfamily of fibroblast growth factors (FGFs) that are incapable of functioning as growth factors, are intracellular modulators of Na(+) channels and have been linked to neurodegenerative diseases. Although certain FHFs have been found in embryonic heart, they have not been reported in adult heart, and they have not been shown to regulate endogenous cardiac Na(+) channels or to participate in cardiac pathophysiology. OBJECTIVE We tested whether FHFs regulate Na(+) channels in murine heart. METHODS AND RESULTS We demonstrated that isoforms of FGF13 are the predominant FHFs in adult mouse ventricular myocytes. FGF13 binds directly to, and colocalizes with, the Na(V)1.5 Na(+) channel in the sarcolemma of adult mouse ventricular myocytes. Knockdown of FGF13 in adult mouse ventricular myocytes revealed a loss of function of Na(V)1.5-reduced Na(+) current density, decreased Na(+) channel availability, and slowed Na(V)1.5-reduced Na(+) current recovery from inactivation. Cell surface biotinylation experiments showed ≈45% reduction in Na(V)1.5 protein at the sarcolemma after FGF13 knockdown, whereas no changes in whole-cell Na(V)1.5 protein or in mRNA level were observed. Optical imaging in neonatal rat ventricular myocyte monolayers demonstrated slowed conduction velocity and a reduced maximum capture rate after FGF13 knockdown. CONCLUSION These findings show that FHFs are potent regulators of Na(+) channels in adult ventricular myocytes and suggest that loss-of-function mutations in FHFs may underlie a similar set of cardiac arrhythmias and cardiomyopathies that result from Na(V)1.5 loss-of-function mutations.
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Affiliation(s)
- Chuan Wang
- Departments of Medicine/Cardiology, Duke University Medical Center, Durham, NC, USA
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Marelli C, Cazeneuve C, Brice A, Stevanin G, Dürr A. Autosomal dominant cerebellar ataxias. Rev Neurol (Paris) 2011; 167:385-400. [PMID: 21546047 DOI: 10.1016/j.neurol.2011.01.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 01/27/2011] [Indexed: 12/30/2022]
Abstract
Cerebellar ataxias with autosomal dominant transmission (ADCA) are far rarer than sporadic cases of cerebellar ataxia. The identification of genes involved in dominant forms has confirmed the genetic heterogeneity of these conditions and of the underlying mechanisms and pathways. To date, at least 28 genetic loci and, among them, 20 genes have been identified. In many instances, the phenotype is not restricted to cerebellar dysfunction but includes more complex multisystemic neurological deficits. Seven ADCA (SCA1, 2, 3, 6, 7, 17, and dentatorubro-pallido-luysian atrophy) are caused by repeat expansions in the corresponding proteins; phenotype-genotype correlations have shown that repeat size influences the progression of the disease, its severity and clinical differences among patients, including the phenomenon of anticipation between generations. All other ADCA are caused either by non-coding repeat expansions, conventional mutations or large rearrangements in genes with different functions. This review will focus on the genetic features of ADCA and on the clinical differences among the different forms.
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Affiliation(s)
- C Marelli
- Département de génétique et cytogénétique, consultation de génétique clinique, CHU Pitié-Salpêtrière, AP-HP, 47, boulevard de l'Hôpital, 75013 Paris, France
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Itoh N, Ornitz DM. Fibroblast growth factors: from molecular evolution to roles in development, metabolism and disease. J Biochem 2010; 149:121-30. [PMID: 20940169 DOI: 10.1093/jb/mvq121] [Citation(s) in RCA: 493] [Impact Index Per Article: 35.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Fibroblast growth factors (FGFs) are a family of structurally related polypeptides that are essential for embryonic development and that function postnatally as homoeostatic factors, in the response to injury, in the regulation of electrical excitability of cells and as hormones that regulate metabolism. In humans, FGF signalling is involved in developmental, neoplastic, metabolic and neurological diseases. Fgfs have been identified in metazoans but not in unicellular organisms. In vertebrates, FGFs can be classified as having intracrine, paracrine and endocrine functions. Paracrine and endocrine FGFs act via cell-surface FGF receptors (FGFRs); while, intracrine FGFs act independent of FGFRs. The evolutionary history of the Fgf family indicates that an intracrine Fgf is the likely ancestor of the Fgf family. During metazoan evolution, the Fgf family expanded in two phases, after the separation of protostomes and deuterostomes and in the evolution of early vertebrates. These expansions enabled FGFs to acquire diverse actions and functions.
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Affiliation(s)
- Nobuyuki Itoh
- Department of Genetic Biochemistry, Kyoto University Graduate School of Pharmaceutical Sciences, Kyoto, Japan.
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