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Farooq S, Lone ML, Ul Haq A, Parveen S, Altaf F, Tahir I. Signalling cascades choreographing petal cell death: implications for postharvest quality. PLANT MOLECULAR BIOLOGY 2024; 114:63. [PMID: 38805152 DOI: 10.1007/s11103-024-01449-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 04/01/2024] [Indexed: 05/29/2024]
Abstract
Senescence is a multifaceted and dynamic developmental phase pivotal in the plant's lifecycle, exerting significant influence and involving intricate regulatory mechanisms marked by a variety of structural, biochemical and molecular alterations. Biochemical changes, including reactive oxygen species (ROS) generation, membrane deterioration, nucleic acid degradation and protein degradation, characterize flower senescence. The progression of senescence entails a meticulously orchestrated network of interconnected molecular mechanisms and signalling pathways, ensuring its synchronized and efficient execution. Within flowering plants, petal senescence emerges as a crucial aspect significantly impacting flower longevity and postharvest quality, emphasizing the pressing necessity of unravelling the underlying signalling cascades orchestrating this process. Understanding the complex signalling pathways regulating petal senescence holds paramount importance, not only shedding light on the broader phenomenon of plant senescence but also paving the way for the development of targeted strategies to enhance the postharvest longevity of cut flowers. Various signalling pathways participate in petal senescence, encompassing hormone signalling, calcium signalling, protein kinase signalling and ROS signalling. Among these, the ethylene signalling pathway is extensively studied, and the manipulation of genes associated with ethylene biosynthesis or signal transduction has demonstrated the potential to enhance flower longevity. A thorough understanding of these complex pathways is critical for effectively delaying flower senescence, thereby enhancing postharvest quality and ornamental value. Therefore, this review adopts a viewpoint that combines fundamental research into the molecular intricacies of senescence with a practical orientation towards developing strategies for improving the postharvest quality of cut flowers. The innovation of this review is to shed light on the pivotal signalling cascades underpinning flower senescence and offer insights into potential approaches for modulating these pathways to postpone petal senescence in ornamental plants.
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Affiliation(s)
- Sumira Farooq
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India
| | - Mohammad Lateef Lone
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India
| | - Aehsan Ul Haq
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India
| | - Shazia Parveen
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India
| | - Foziya Altaf
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India
| | - Inayatullah Tahir
- Plant Physiology and Biochemistry Research Laboratory, Department of Botany, University of Kashmir, Srinagar, 190006, India.
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2
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Santarelli S, Londero C, Soldano A, Candelaresi C, Todeschini L, Vernizzi L, Bellosta P. Drosophila melanogaster as a model to study autophagy in neurodegenerative diseases induced by proteinopathies. Front Neurosci 2023; 17:1082047. [PMID: 37274187 PMCID: PMC10232775 DOI: 10.3389/fnins.2023.1082047] [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: 10/27/2022] [Accepted: 04/14/2023] [Indexed: 06/06/2023] Open
Abstract
Proteinopathies are a large group of neurodegenerative diseases caused by both genetic and sporadic mutations in particular genes which can lead to alterations of the protein structure and to the formation of aggregates, especially toxic for neurons. Autophagy is a key mechanism for clearing those aggregates and its function has been strongly associated with the ubiquitin-proteasome system (UPS), hence mutations in both pathways have been associated with the onset of neurodegenerative diseases, particularly those induced by protein misfolding and accumulation of aggregates. Many crucial discoveries regarding the molecular and cellular events underlying the role of autophagy in these diseases have come from studies using Drosophila models. Indeed, despite the physiological and morphological differences between the fly and the human brain, most of the biochemical and molecular aspects regulating protein homeostasis, including autophagy, are conserved between the two species.In this review, we will provide an overview of the most common neurodegenerative proteinopathies, which include PolyQ diseases (Huntington's disease, Spinocerebellar ataxia 1, 2, and 3), Amyotrophic Lateral Sclerosis (C9orf72, SOD1, TDP-43, FUS), Alzheimer's disease (APP, Tau) Parkinson's disease (a-syn, parkin and PINK1, LRRK2) and prion diseases, highlighting the studies using Drosophila that have contributed to understanding the conserved mechanisms and elucidating the role of autophagy in these diseases.
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Affiliation(s)
- Stefania Santarelli
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Chiara Londero
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Alessia Soldano
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Carlotta Candelaresi
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Leonardo Todeschini
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
| | - Luisa Vernizzi
- Institute of Molecular Life Sciences, University of Zurich, Zürich, Switzerland
| | - Paola Bellosta
- Department of Cellular, Computational and Integrative Biology (CiBiO), University of Trento, Trento, Italy
- Department of Medicine, NYU Langone Medical Center, New York, NY, United States
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3
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Sundberg CA, Lakk M, Paul S, Figueroa KP, Scoles DR, Pulst SM, Križaj D. The RNA-binding protein and stress granule component ATAXIN-2 is expressed in mouse and human tissues associated with glaucoma pathogenesis. J Comp Neurol 2022; 530:537-552. [PMID: 34350994 PMCID: PMC8716417 DOI: 10.1002/cne.25228] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 07/06/2021] [Indexed: 02/03/2023]
Abstract
Polyglutamine repeat expansions in the Ataxin-2 (ATXN2) gene were first implicated in Spinocerebellar Ataxia Type 2, a disease associated with degeneration of motor neurons and Purkinje cells. Recent studies linked single nucleotide polymorphisms in the gene to elevated intraocular pressure in primary open angle glaucoma (POAG); yet, the localization of ATXN2 across glaucoma-relevant tissues of the vertebrate eye has not been thoroughly examined. This study characterizes ATXN2 expression in the mouse and human retina, and anterior eye, using an antibody validated in ATXN2-/- retinas. ATXN2-ir was localized to cytosolic sub compartments in retinal ganglion cell (RGC) somata and proximal dendrites in addition to GABAergic, glycinergic, and cholinergic amacrine cells in the inner plexiform layer (IPL) and displaced amacrine cells. Human, but not mouse retinas showed modest immunolabeling of bipolar cells. ATXN2 immunofluorescence was prominent in the trabecular meshwork and pigmented and nonpigmented cells of the ciliary body, with analyses of primary human trabecular meshwork cells confirming the finding. The expression of ATXN2 in key POAG-relevant ocular tissues supports the potential role in autophagy and stress granule formation in response to ocular hypertension.
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Affiliation(s)
- Chad A. Sundberg
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Monika Lakk
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Sharan Paul
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Karla P. Figueroa
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Daniel R. Scoles
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, Salt Lake City, Utah, USA
| | - David Križaj
- Department of Ophthalmology & Visual Sciences, University of Utah, Salt Lake City, Utah, USA
- Department of Bioengineering, University of Utah, Salt Lake City, Utah, USA
- Department of Neurobiology & Anatomy, University of Utah, Salt Lake City, Utah, USA
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4
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Del Castillo U, Norkett R, Lu W, Serpinskaya A, Gelfand VI. Ataxin-2 is essential for cytoskeletal dynamics and neurodevelopment in Drosophila. iScience 2022; 25:103536. [PMID: 34977501 PMCID: PMC8689088 DOI: 10.1016/j.isci.2021.103536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 08/19/2021] [Accepted: 11/25/2021] [Indexed: 12/03/2022] Open
Abstract
Ataxin-2 (Atx2) is a highly conserved RNA binding protein. Atx2 undergoes polyglutamine expansion leading to amyotrophic lateral sclerosis (ALS) or spinocerebellar ataxia type 2 (SCA2). However, the physiological functions of Atx2 in neurons remain unknown. Here, using the powerful genetics of Drosophila, we show that Atx2 is essential for normal neuronal cytoskeletal dynamics and organelle trafficking. Upon neuron-specific Atx2 loss, the microtubule and actin networks were abnormally stabilized and cargo transport was drastically inhibited. Depletion of Atx2 caused multiple morphological defects in the nervous system of third instar larvae. These include reduced brain size, impaired axon development, and decreased dendrite outgrowth. Defects in the nervous system caused loss of the ability to crawl and lethality at the pupal stage. Taken together, these data mark Atx2 as a major regulator of cytoskeletal dynamics and denote Atx2 as an essential gene in neurodevelopment, as well as a neurodegenerative factor. Atx2 is a major regulator of the cytoskeleton in neurons Atx2 is responsible for maintaining dynamic cytoskeletal networks Atx2 depletion in the Drosophila larval CNS severely impairs organelle transport Atx2 is necessary for correct neurite outgrowth and CNS development in Drosophila
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Affiliation(s)
- Urko Del Castillo
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Rosalind Norkett
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Wen Lu
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Anna Serpinskaya
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Vladimir I Gelfand
- Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
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Rounds JC, Corgiat EB, Ye C, Behnke JA, Kelly SM, Corbett AH, Moberg KH. The disease-associated proteins Drosophila Nab2 and Ataxin-2 interact with shared RNAs and coregulate neuronal morphology. Genetics 2022; 220:iyab175. [PMID: 34791182 PMCID: PMC8733473 DOI: 10.1093/genetics/iyab175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 09/27/2021] [Indexed: 01/05/2023] Open
Abstract
Nab2 encodes the Drosophila melanogaster member of a conserved family of zinc finger polyadenosine RNA-binding proteins (RBPs) linked to multiple steps in post-transcriptional regulation. Mutation of the Nab2 human ortholog ZC3H14 gives rise to an autosomal recessive intellectual disability but understanding of Nab2/ZC3H14 function in metazoan nervous systems is limited, in part because no comprehensive identification of metazoan Nab2/ZC3H14-associated RNA transcripts has yet been conducted. Moreover, many Nab2/ZC3H14 functional protein partnerships remain unidentified. Here, we present evidence that Nab2 genetically interacts with Ataxin-2 (Atx2), which encodes a neuronal translational regulator, and that these factors coordinately regulate neuronal morphology, circadian behavior, and adult viability. We then present the first high-throughput identifications of Nab2- and Atx2-associated RNAs in Drosophila brain neurons using RNA immunoprecipitation-sequencing (RIP-Seq). Critically, the RNA interactomes of each RBP overlap, and Nab2 exhibits high specificity in its RNA associations in neurons in vivo, associating with a small fraction of all polyadenylated RNAs. The identities of shared associated transcripts (e.g., drk, me31B, stai) and of transcripts specific to Nab2 or Atx2 (e.g., Arpc2 and tea) promise insight into neuronal functions of, and genetic interactions between, each RBP. Consistent with prior biochemical studies, Nab2-associated neuronal RNAs are overrepresented for internal A-rich motifs, suggesting these sequences may partially mediate Nab2 target selection. These data support a model where Nab2 functionally opposes Atx2 in neurons, demonstrate Nab2 shares associated neuronal RNAs with Atx2, and reveal Drosophila Nab2 associates with a more specific subset of polyadenylated mRNAs than its polyadenosine affinity alone may suggest.
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Affiliation(s)
- J Christopher Rounds
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Edwin B Corgiat
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Changtian Ye
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Joseph A Behnke
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Seth M Kelly
- Department of Biology, The College of Wooster, Wooster, OH 44691, USA
| | - Anita H Corbett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Kenneth H Moberg
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA 30322, USA
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6
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Sechi S, Karimpour-Ghahnavieh A, Frappaolo A, Di Francesco L, Piergentili R, Schininà E, D’Avino PP, Giansanti MG. Identification of GOLPH3 Partners in Drosophila Unveils Potential Novel Roles in Tumorigenesis and Neural Disorders. Cells 2021; 10:cells10092336. [PMID: 34571985 PMCID: PMC8468827 DOI: 10.3390/cells10092336] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/01/2021] [Accepted: 09/03/2021] [Indexed: 12/28/2022] Open
Abstract
Golgi phosphoprotein 3 (GOLPH3) is a highly conserved peripheral membrane protein localized to the Golgi apparatus and the cytosol. GOLPH3 binding to Golgi membranes depends on phosphatidylinositol 4-phosphate [PI(4)P] and regulates Golgi architecture and vesicle trafficking. GOLPH3 overexpression has been correlated with poor prognosis in several cancers, but the molecular mechanisms that link GOLPH3 to malignant transformation are poorly understood. We recently showed that PI(4)P-GOLPH3 couples membrane trafficking with contractile ring assembly during cytokinesis in dividing Drosophila spermatocytes. Here, we use affinity purification coupled with mass spectrometry (AP-MS) to identify the protein-protein interaction network (interactome) of Drosophila GOLPH3 in testes. Analysis of the GOLPH3 interactome revealed enrichment for proteins involved in vesicle-mediated trafficking, cell proliferation and cytoskeleton dynamics. In particular, we found that dGOLPH3 interacts with the Drosophila orthologs of Fragile X mental retardation protein and Ataxin-2, suggesting a potential role in the pathophysiology of disorders of the nervous system. Our findings suggest novel molecular targets associated with GOLPH3 that might be relevant for therapeutic intervention in cancers and other human diseases.
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Affiliation(s)
- Stefano Sechi
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Angela Karimpour-Ghahnavieh
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Anna Frappaolo
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Laura Di Francesco
- Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (L.D.F.); (E.S.)
| | - Roberto Piergentili
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
| | - Eugenia Schininà
- Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (L.D.F.); (E.S.)
| | - Pier Paolo D’Avino
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK;
| | - Maria Grazia Giansanti
- Istituto di Biologia e Patologia Molecolari del CNR, c/o Dipartimento di Biologia e Biotecnologie, Sapienza Università di Roma, Piazzale A. Moro 5, 00185 Roma, Italy; (S.S.); (A.K.-G.); (A.F.); (R.P.)
- Correspondence: ; Tel.: +39-064-991-2555
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7
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Liguori F, Amadio S, Volonté C. Fly for ALS: Drosophila modeling on the route to amyotrophic lateral sclerosis modifiers. Cell Mol Life Sci 2021; 78:6143-6160. [PMID: 34322715 PMCID: PMC11072332 DOI: 10.1007/s00018-021-03905-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 12/11/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is a rare, devastating disease, causing movement impairment, respiratory failure and ultimate death. A plethora of genetic, cellular and molecular mechanisms are involved in ALS signature, although the initiating causes and progressive pathological events are far from being understood. Drosophila research has produced seminal discoveries for more than a century and has been successfully used in the past 25 years to untangle the process of ALS pathogenesis, and recognize potential markers and novel strategies for therapeutic solutions. This review will provide an updated view of several ALS modifiers validated in C9ORF72, SOD1, FUS, TDP-43 and Ataxin-2 Drosophila models. We will discuss basic and preclinical findings, illustrating recent developments and novel breakthroughs, also depicting unsettled challenges and limitations in the Drosophila-ALS field. We intend to stimulate a renewed debate on Drosophila as a screening route to identify more successful disease modifiers and neuroprotective agents.
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Affiliation(s)
- Francesco Liguori
- Preclinical Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 65, 00143, Rome, Italy
| | - Susanna Amadio
- Preclinical Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 65, 00143, Rome, Italy
| | - Cinzia Volonté
- Preclinical Neuroscience, IRCCS Fondazione Santa Lucia, Via del Fosso di Fiorano 65, 00143, Rome, Italy.
- Institute for Systems Analysis and Computer Science "A. Ruberti", National Research Council (IASI-CNR), Via dei Taurini 19, 00185, Rome, Italy.
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Canet-Pons J, Sen NE, Arsović A, Almaguer-Mederos LE, Halbach MV, Key J, Döring C, Kerksiek A, Picchiarelli G, Cassel R, René F, Dieterlé S, Fuchs NV, König R, Dupuis L, Lütjohann D, Gispert S, Auburger G. Atxn2-CAG100-KnockIn mouse spinal cord shows progressive TDP43 pathology associated with cholesterol biosynthesis suppression. Neurobiol Dis 2021; 152:105289. [PMID: 33577922 DOI: 10.1016/j.nbd.2021.105289] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2020] [Revised: 12/11/2020] [Accepted: 02/03/2021] [Indexed: 12/12/2022] Open
Abstract
Large polyglutamine expansions in Ataxin-2 (ATXN2) cause multi-system nervous atrophy in Spinocerebellar Ataxia type 2 (SCA2). Intermediate size expansions carry a risk for selective motor neuron degeneration, known as Amyotrophic Lateral Sclerosis (ALS). Conversely, the depletion of ATXN2 prevents disease progression in ALS. Although ATXN2 interacts directly with RNA, and in ALS pathogenesis there is a crucial role of RNA toxicity, the affected functional pathways remain ill defined. Here, we examined an authentic SCA2 mouse model with Atxn2-CAG100-KnockIn for a first definition of molecular mechanisms in spinal cord pathology. Neurophysiology of lower limbs detected sensory neuropathy rather than motor denervation. Triple immunofluorescence demonstrated cytosolic ATXN2 aggregates sequestrating TDP43 and TIA1 from the nucleus. In immunoblots, this was accompanied by elevated CASP3, RIPK1 and PQBP1 abundance. RT-qPCR showed increase of Grn, Tlr7 and Rnaset2 mRNA versus Eif5a2, Dcp2, Uhmk1 and Kif5a decrease. These SCA2 findings overlap well with known ALS features. Similar to other ataxias and dystonias, decreased mRNA levels for Unc80, Tacr1, Gnal, Ano3, Kcna2, Elovl5 and Cdr1 contrasted with Gpnmb increase. Preterminal stage tissue showed strongly activated microglia containing ATXN2 aggregates, with parallel astrogliosis. Global transcriptome profiles from stages of incipient motor deficit versus preterminal age identified molecules with progressive downregulation, where a cluster of cholesterol biosynthesis enzymes including Dhcr24, Msmo1, Idi1 and Hmgcs1 was prominent. Gas chromatography demonstrated a massive loss of crucial cholesterol precursor metabolites. Overall, the ATXN2 protein aggregation process affects diverse subcellular compartments, in particular stress granules, endoplasmic reticulum and receptor tyrosine kinase signaling. These findings identify new targets and potential biomarkers for neuroprotective therapies.
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Affiliation(s)
- Júlia Canet-Pons
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Nesli-Ece Sen
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsović
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Luis-Enrique Almaguer-Mederos
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Center for Investigation and Rehabilitation of Hereditary Ataxias (CIRAH), Holguín, Cuba
| | - Melanie V Halbach
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Jana Key
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany; Faculty of Biosciences, Goethe University, 60438 Frankfurt am Main, Germany
| | - Claudia Döring
- Dr. Senckenberg Institute of Pathology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Anja Kerksiek
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Gina Picchiarelli
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Raphaelle Cassel
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Frédérique René
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Stéphane Dieterlé
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Nina V Fuchs
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Renate König
- Host-Pathogen Interactions, Paul-Ehrlich-Institute, 63225 Langen, Germany
| | - Luc Dupuis
- UMRS-1118 INSERM, Faculty of Medicine, University of Strasbourg, 67000 Strasbourg, France
| | - Dieter Lütjohann
- Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, 53127 Bonn, Nordrhein-Westfalen, Germany
| | - Suzana Gispert
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Medical Faculty, Goethe University, 60590 Frankfurt am Main, Germany.
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Kliuchnikova AA, Goncharov AO, Levitsky LI, Pyatnitskiy MA, Novikova SE, Kuznetsova KG, Ivanov MV, Ilina IY, Farafonova TE, Zgoda VG, Gorshkov MV, Moshkovskii SA. Proteome-Wide Analysis of ADAR-Mediated Messenger RNA Editing during Fruit Fly Ontogeny. J Proteome Res 2020; 19:4046-4060. [PMID: 32866021 DOI: 10.1021/acs.jproteome.0c00347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Adenosine-to-inosine RNA editing is an enzymatic post-transcriptional modification which modulates immunity and neural transmission in multicellular organisms. In particular, it involves editing of mRNA codons with the resulting amino acid substitutions. We identified such sites for developmental proteomes of Drosophila melanogaster at the protein level using available data for 15 stages of fruit fly development from egg to imago and 14 time points of embryogenesis. In total, 40 sites were obtained, each belonging to a unique protein, including four sites related to embryogenesis. The interactome analysis has revealed that the majority of the editing-recoded proteins were associated with synaptic vesicle trafficking and actomyosin organization. Quantitation data analysis suggested the existence of a phase-specific RNA editing regulation with yet unknown mechanisms. These findings supported the transcriptome analysis results, which showed that a burst in the RNA editing occurs during insect metamorphosis from pupa to imago. Finally, targeted proteomic analysis was performed to quantify editing-recoded and genomically encoded versions of five proteins in brains of larvae, pupae, and imago insects, which showed a clear tendency toward an increase in the editing rate for each of them. These results will allow a better understanding of the protein role in physiological effects of RNA editing.
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Affiliation(s)
- Anna A Kliuchnikova
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia.,Pirogov Russian National Research Medical University, 1, Ostrovityanova, Moscow 117997, Russia
| | - Anton O Goncharov
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia.,Institute of Biomedical Chemistry, 10, Pogodinskaya, Moscow 119121, Russia
| | - Lev I Levitsky
- V.L. Talrose Institute for Energy Problems of Chemical Physics, N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 38, bld. 1, Leninsky Prospect, Moscow 119334, Russia
| | - Mikhail A Pyatnitskiy
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia.,Institute of Biomedical Chemistry, 10, Pogodinskaya, Moscow 119121, Russia
| | | | - Ksenia G Kuznetsova
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia
| | - Mark V Ivanov
- V.L. Talrose Institute for Energy Problems of Chemical Physics, N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 38, bld. 1, Leninsky Prospect, Moscow 119334, Russia
| | - Irina Y Ilina
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia
| | | | - Victor G Zgoda
- Institute of Biomedical Chemistry, 10, Pogodinskaya, Moscow 119121, Russia.,Skolkovo Institute of Science and Technology, 30, bld. 1, Bolshoy Boulevard, Moscow 121205, Russia
| | - Mikhail V Gorshkov
- V.L. Talrose Institute for Energy Problems of Chemical Physics, N.N. Semenov Federal Research Center for Chemical Physics, Russian Academy of Sciences, 38, bld. 1, Leninsky Prospect, Moscow 119334, Russia
| | - Sergei A Moshkovskii
- Federal Research and Clinical Center of Physical-Chemical Medicine, 1a, Malaya Pirogovskaya, Moscow 119435, Russia.,Pirogov Russian National Research Medical University, 1, Ostrovityanova, Moscow 117997, Russia
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10
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Hansen M, Zeddies S, Meinders M, di Summa F, Rollmann E, van Alphen FP, Hoogendijk AJ, Moore KS, Halbach M, Gutiérrez L, van den Biggelaar M, Thijssen-Timmer DC, Auburger GW, van den Akker E, von Lindern M. The RNA-Binding Protein ATXN2 is Expressed during Megakaryopoiesis and May Control Timing of Gene Expression. Int J Mol Sci 2020; 21:ijms21030967. [PMID: 32024018 PMCID: PMC7037754 DOI: 10.3390/ijms21030967] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/21/2020] [Accepted: 01/30/2020] [Indexed: 12/13/2022] Open
Abstract
Megakaryopoiesis is the process during which megakaryoblasts differentiate to polyploid megakaryocytes that can subsequently shed thousands of platelets in the circulation. Megakaryocytes accumulate mRNA during their maturation, which is required for the correct spatio-temporal production of cytoskeletal proteins, membranes and platelet-specific granules, and for the subsequent shedding of thousands of platelets per cell. Gene expression profiling identified the RNA binding protein ATAXIN2 (ATXN2) as a putative novel regulator of megakaryopoiesis. ATXN2 expression is high in CD34+/CD41+ megakaryoblasts and sharply decreases upon maturation to megakaryocytes. ATXN2 associates with DDX6 suggesting that it may mediate repression of mRNA translation during early megakaryopoiesis. Comparative transcriptome and proteome analysis on megakaryoid cells (MEG-01) with differential ATXN2 expression identified ATXN2 dependent gene expression of mRNA and protein involved in processes linked to hemostasis. Mice deficient for Atxn2 did not display differences in bleeding times, but the expression of key surface receptors on platelets, such as ITGB3 (carries the CD61 antigen) and CD31 (PECAM1), was deregulated and platelet aggregation upon specific triggers was reduced.
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Affiliation(s)
- Marten Hansen
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Sabrina Zeddies
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Marjolein Meinders
- Department Blood Cell Research, Sanquin Research and Landsteiner Laboratory, Academic Medical Centre, University of Amsterdam,1066CX Amsterdam, The Netherlands; (M.M.); (L.G.)
| | - Franca di Summa
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Ewa Rollmann
- Experimental Neurology, Goethe University Medical School, 60528 Frankfurt am Main, Germany; (E.R.); (M.H.)
| | - Floris P.J. van Alphen
- Department of Molecular and Cellular Hemostasis, Sanquin Research, 1066CX Amsterdam, The Netherlands (A.J.H.); (M.v.d.B.)
| | - Arjan J. Hoogendijk
- Department of Molecular and Cellular Hemostasis, Sanquin Research, 1066CX Amsterdam, The Netherlands (A.J.H.); (M.v.d.B.)
| | - Kat S. Moore
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Melanie Halbach
- Experimental Neurology, Goethe University Medical School, 60528 Frankfurt am Main, Germany; (E.R.); (M.H.)
| | - Laura Gutiérrez
- Department Blood Cell Research, Sanquin Research and Landsteiner Laboratory, Academic Medical Centre, University of Amsterdam,1066CX Amsterdam, The Netherlands; (M.M.); (L.G.)
| | - Maartje van den Biggelaar
- Department of Molecular and Cellular Hemostasis, Sanquin Research, 1066CX Amsterdam, The Netherlands (A.J.H.); (M.v.d.B.)
| | - Daphne C. Thijssen-Timmer
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Georg W.J. Auburger
- Experimental Neurology, Goethe University Medical School, 60528 Frankfurt am Main, Germany; (E.R.); (M.H.)
| | - Emile van den Akker
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
| | - Marieke von Lindern
- Department Hematopoiesis, Sanquin Research, and Landsteiner Laboratory, Amsterdam University Medical Centre, 1066CX Amsterdam, The Netherlands; (M.H.); (S.Z.); (F.d.S.); (K.S.M.); (D.C.T.-T.); (E.v.d.A.)
- Correspondence: ; Tel.: +31-6-1203-7801
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11
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Sen NE, Arsovic A, Meierhofer D, Brodesser S, Oberschmidt C, Canet-Pons J, Kaya ZE, Halbach MV, Gispert S, Sandhoff K, Auburger G. In Human and Mouse Spino-Cerebellar Tissue, Ataxin-2 Expansion Affects Ceramide-Sphingomyelin Metabolism. Int J Mol Sci 2019; 20:E5854. [PMID: 31766565 PMCID: PMC6928749 DOI: 10.3390/ijms20235854] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/19/2019] [Accepted: 11/20/2019] [Indexed: 02/08/2023] Open
Abstract
Ataxin-2 (human gene symbol ATXN2) acts during stress responses, modulating mRNA translation and nutrient metabolism. Ataxin-2 knockout mice exhibit progressive obesity, dyslipidemia, and insulin resistance. Conversely, the progressive ATXN2 gain of function due to the fact of polyglutamine (polyQ) expansions leads to a dominantly inherited neurodegenerative process named spinocerebellar ataxia type 2 (SCA2) with early adipose tissue loss and late muscle atrophy. We tried to understand lipid dysregulation in a SCA2 patient brain and in an authentic mouse model. Thin layer chromatography of a patient cerebellum was compared to the lipid metabolome of Atxn2-CAG100-Knockin (KIN) mouse spinocerebellar tissue. The human pathology caused deficits of sulfatide, galactosylceramide, cholesterol, C22/24-sphingomyelin, and gangliosides GM1a/GD1b despite quite normal levels of C18-sphingomyelin. Cerebellum and spinal cord from the KIN mouse showed a consistent decrease of various ceramides with a significant elevation of sphingosine in the more severely affected spinal cord. Deficiency of C24/26-sphingomyelins contrasted with excess C18/20-sphingomyelin. Spinocerebellar expression profiling revealed consistent reductions of CERS protein isoforms, Sptlc2 and Smpd3, but upregulation of Cers2 mRNA, as prominent anomalies in the ceramide-sphingosine metabolism. Reduction of Asah2 mRNA correlated to deficient S1P levels. In addition, downregulations for the elongase Elovl1, Elovl4, Elovl5 mRNAs and ELOVL4 protein explain the deficit of very long-chain sphingomyelin. Reduced ASMase protein levels correlated to the accumulation of long-chain sphingomyelin. Overall, a deficit of myelin lipids was prominent in SCA2 nervous tissue at prefinal stage and not compensated by transcriptional adaptation of several metabolic enzymes. Myelination is controlled by mTORC1 signals; thus, our human and murine observations are in agreement with the known role of ATXN2 yeast, nematode, and mouse orthologs as mTORC1 inhibitors and autophagy promoters.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Faculty of Biosciences, Goethe-University, 60438 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, Ihnestrasse 63-73, 14195 Berlin, Germany;
| | - Susanne Brodesser
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Carola Oberschmidt
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Júlia Canet-Pons
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Zeynep-Ece Kaya
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
- Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Melanie-Vanessa Halbach
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Suzana Gispert
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
| | - Konrad Sandhoff
- Membrane Biology and Lipid Biochemistry Unit, Life and Medical Sciences Institute, University of Bonn, 53121 Bonn, Germany;
| | - Georg Auburger
- Experimental Neurology, Building 89, Goethe University Medical Faculty, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany; (N.-E.S.); (A.A.); (C.O.); (J.C.-P.); (Z.-E.K.); (M.-V.H.); (S.G.)
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12
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Park S, Park SK, Watanabe N, Hashimoto T, Iwatsubo T, Shelkovnikova TA, Liebman SW. Calcium-responsive transactivator (CREST) toxicity is rescued by loss of PBP1/ATXN2 function in a novel yeast proteinopathy model and in transgenic flies. PLoS Genet 2019; 15:e1008308. [PMID: 31390360 PMCID: PMC6699716 DOI: 10.1371/journal.pgen.1008308] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 08/19/2019] [Accepted: 07/12/2019] [Indexed: 12/26/2022] Open
Abstract
Proteins associated with familial neurodegenerative disease often aggregate in patients’ neurons. Several such proteins, e.g. TDP-43, aggregate and are toxic when expressed in yeast. Deletion of the ATXN2 ortholog, PBP1, reduces yeast TDP-43 toxicity, which led to identification of ATXN2 as an amyotrophic lateral sclerosis (ALS) risk factor and therapeutic target. Likewise, new yeast neurodegenerative disease models could facilitate identification of other risk factors and targets. Mutations in SS18L1, encoding the calcium-responsive transactivator (CREST) chromatin-remodeling protein, are associated with ALS. We show that CREST is toxic in yeast and forms nuclear and occasionally cytoplasmic foci that stain with Thioflavin-T, a dye indicative of amyloid-like protein. Like the yeast chromatin-remodeling factor SWI1, CREST inhibits silencing of FLO genes. Toxicity of CREST is enhanced by the [PIN+] prion and reduced by deletion of the HSP104 chaperone required for the propagation of many yeast prions. Likewise, deletion of PBP1 reduced CREST toxicity and aggregation. In accord with the yeast data, we show that the Drosophila ortholog of human ATXN2, dAtx2, is a potent enhancer of CREST toxicity. Downregulation of dAtx2 in flies overexpressing CREST in retinal ganglion cells was sufficient to largely rescue the severe degenerative phenotype induced by human CREST. Overexpression caused considerable co-localization of CREST and PBP1/ATXN2 in cytoplasmic foci in both yeast and mammalian cells. Thus, co-aggregation of CREST and PBP1/ATXN2 may serve as one of the mechanisms of PBP1/ATXN2-mediated toxicity. These results extend the spectrum of ALS associated proteins whose toxicity is regulated by PBP1/ATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases. Mutations in the calcium-responsive transactivator (CREST) protein have been shown to cause amyotrophic lateral sclerosis (ALS). Here we show that the human CREST protein expressed in yeast forms largely nuclear aggregates and is toxic. We also show that the HSP104 chaperone required for propagation of yeast prions is likewise required for CREST toxicity. Furthermore deletion of HSP104 affects CREST aggregation. ATXN2, previously shown to modify ALS toxicity caused by mutations in the TDP-43 encoding gene, also modifies toxicity of CREST expressed in either yeast or flies. In addition, deletion of the yeast ATXN2 ortholog reduces CREST aggregation. These results extend the spectrum of ALS associated proteins whose toxicity is regulated by ATXN2, suggesting that therapies targeting ATXN2 may be effective for a wide range of neurodegenerative diseases.
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Affiliation(s)
- Sangeun Park
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
| | - Sei-Kyoung Park
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
| | | | | | | | | | - Susan W. Liebman
- Department of Pharmacology, University of Nevada, Reno, Untied States of America
- * E-mail:
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13
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Sen NE, Canet-Pons J, Halbach MV, Arsovic A, Pilatus U, Chae WH, Kaya ZE, Seidel K, Rollmann E, Mittelbronn M, Meierhofer D, De Zeeuw CI, Bosman LWJ, Gispert S, Auburger G. Generation of an Atxn2-CAG100 knock-in mouse reveals N-acetylaspartate production deficit due to early Nat8l dysregulation. Neurobiol Dis 2019; 132:104559. [PMID: 31376479 DOI: 10.1016/j.nbd.2019.104559] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/16/2019] [Accepted: 07/30/2019] [Indexed: 12/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disorder caused by CAG-expansion mutations in the ATXN2 gene, mainly affecting motor neurons in the spinal cord and Purkinje neurons in the cerebellum. While the large expansions were shown to cause SCA2, the intermediate length expansions lead to increased risk for several atrophic processes including amyotrophic lateral sclerosis and Parkinson variants, e.g. progressive supranuclear palsy. Intense efforts to pioneer a neuroprotective therapy for SCA2 require longitudinal monitoring of patients and identification of crucial molecular pathways. The ataxin-2 (ATXN2) protein is mainly involved in RNA translation control and regulation of nutrient metabolism during stress periods. The preferential mRNA targets of ATXN2 are yet to be determined. In order to understand the molecular disease mechanism throughout different prognostic stages, we generated an Atxn2-CAG100-knock-in (KIN) mouse model of SCA2 with intact murine ATXN2 expression regulation. Its characterization revealed somatic mosaicism of the expansion, with shortened lifespan, a progressive spatio-temporal pattern of pathology with subsequent phenotypes, and anomalies of brain metabolites such as N-acetylaspartate (NAA), all of which mirror faithfully the findings in SCA2 patients. Novel molecular analyses from stages before the onset of motor deficits revealed a strong selective effect of ATXN2 on Nat8l mRNA which encodes the enzyme responsible for NAA synthesis. This metabolite is a prominent energy store of the brain and a well-established marker for neuronal health. Overall, we present a novel authentic rodent model of SCA2, where in vivo magnetic resonance imaging was feasible to monitor progression and where the definition of earliest transcriptional abnormalities was possible. We believe that this model will not only reveal crucial insights regarding the pathomechanism of SCA2 and other ATXN2-associated disorders, but will also aid in developing gene-targeted therapies and disease prevention.
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Affiliation(s)
- Nesli-Ece Sen
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Júlia Canet-Pons
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Melanie V Halbach
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Aleksandar Arsovic
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Ulrich Pilatus
- Institute of Neuroradiology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Woon-Hyung Chae
- Georg-Speyer-Haus, Institute for Tumor Biology and Experimental Therapy, 60596 Frankfurt am Main, Germany
| | - Zeynep-Ece Kaya
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany; Department of Neurology, Cerrahpasa School of Medicine, Istanbul University, 34098 Istanbul, Turkey
| | - Kay Seidel
- Department of Anatomy II, Institute of Clinical Neuroanatomy, Goethe University, 60590 Frankfurt am Main, Germany
| | - Ewa Rollmann
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Michel Mittelbronn
- Neurological Institute (Edinger Institute), Goethe University, 60590 Frankfurt am Main, Germany; Luxembourg Centre of Neuropathology (LCNP), Luxembourg; Department of Pathology, Laboratoire National de Santé (LNS), Dudelange, Luxembourg; Luxembourg Centre for Systems Biomedicine (LCSB), University of Luxembourg, Esch-sur-Alzette, Luxembourg; Department of Oncology, NORLUX Neuro-Oncology Laboratory, Luxembourg Institute of Health (LIH), Luxembourg
| | - David Meierhofer
- Max Planck Institute for Molecular Genetics, 14195 Berlin, Germany
| | - Chris I De Zeeuw
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences, 1105 BA Amsterdam, the Netherlands; Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Laurens W J Bosman
- Department of Neuroscience, Erasmus Medical Center, 3000 CA Rotterdam, the Netherlands
| | - Suzana Gispert
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany
| | - Georg Auburger
- Experimental Neurology, Goethe University Medical School, 60590 Frankfurt am Main, Germany.
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14
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Cuello Almarales DA, Almaguer Mederos LE. Reponse to: Is Micronucleus Assay Suitable for Biomonitoring Spinocerebellar Ataxia Type 2? Arch Med Res 2019; 50:18-19. [PMID: 31349949 DOI: 10.1016/j.arcmed.2019.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2019] [Accepted: 05/02/2019] [Indexed: 10/26/2022]
Affiliation(s)
- Dany A Cuello Almarales
- Researcher of the Department of Molecular Neurobiology, Center for Investigation and Rehabilitation of Hereditary Ataxias "Carlos J. Finlay", Holguín, Cuba.
| | - Luis E Almaguer Mederos
- Researcher of the Department of Molecular Neurobiology, Center for Investigation and Rehabilitation of Hereditary Ataxias "Carlos J. Finlay", Holguín, Cuba
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15
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del Castillo U, Gnazzo MM, Turpin CGS, Nguyen KCQ, Semaya E, Lam Y, de Cruz MA, Bembenek JN, Hall DH, Riggs B, Gelfand VI, Skop AR. Conserved role for Ataxin-2 in mediating endoplasmic reticulum dynamics. Traffic 2019; 20:436-447. [PMID: 30989774 PMCID: PMC6553494 DOI: 10.1111/tra.12647] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 04/04/2019] [Accepted: 04/05/2019] [Indexed: 12/17/2022]
Abstract
Ataxin-2, a conserved RNA-binding protein, is implicated in the late-onset neurodegenerative disease Spinocerebellar ataxia type-2 (SCA2). SCA2 is characterized by shrunken dendritic arbors and torpedo-like axons within the Purkinje neurons of the cerebellum. Torpedo-like axons have been described to contain displaced endoplasmic reticulum (ER) in the periphery of the cell; however, the role of Ataxin-2 in mediating ER function in SCA2 is unclear. We utilized the Caenorhabditis elegans and Drosophila homologs of Ataxin-2 (ATX-2 and DAtx2, respectively) to determine the role of Ataxin-2 in ER function and dynamics in embryos and neurons. Loss of ATX-2 and DAtx2 resulted in collapse of the ER in dividing embryonic cells and germline, and ultrastructure analysis revealed unique spherical stacks of ER in mature oocytes and fragmented and truncated ER tubules in the embryo. ATX-2 and DAtx2 reside in puncta adjacent to the ER in both C. elegans and Drosophila embryos. Lastly, depletion of DAtx2 in cultured Drosophila neurons recapitulated the shrunken dendritic arbor phenotype of SCA2. ER morphology and dynamics were severely disrupted in these neurons. Taken together, we provide evidence that Ataxin-2 plays an evolutionary conserved role in ER dynamics and morphology in C. elegans and Drosophila embryos during development and in fly neurons, suggesting a possible SCA2 disease mechanism.
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Affiliation(s)
- Urko del Castillo
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Megan M. Gnazzo
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Christopher G. Sorensen Turpin
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - Ken C. Q. Nguyen
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Emily Semaya
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Yuwan Lam
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Matthew A. de Cruz
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Joshua N. Bembenek
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee-Knoxville, Knoxville, Tennessee 37996
| | - David H. Hall
- Center for C. elegans Anatomy, Albert Einstein College of Medicine, Bronx New York, NY 10461
| | - Blake Riggs
- Department of Biology, San Francisco State University, San Francisco, CA 94132
| | - Vladimir I. Gelfand
- Department of Cell and Molecular Biology, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611
| | - Ahna R. Skop
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706
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16
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Vu A, Humphries T, Vogel S, Haberman A. Polyglutamine repeat proteins disrupt actin structure in Drosophila photoreceptors. Mol Cell Neurosci 2018; 93:10-17. [PMID: 30149064 DOI: 10.1016/j.mcn.2018.08.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/17/2018] [Accepted: 08/21/2018] [Indexed: 01/07/2023] Open
Abstract
Expansions of polygutamine-encoding stretches in several genes cause neurodegenerative disorders including Huntington's Disease and Spinocerebellar Ataxia type 3. Expression of the human disease alleles in Drosophila melanogaster neurons recapitulates cellular features of these disorders, and has therefore been used to model the cell biology of these diseases. Here, we show that polyglutamine disease alleles expressed in Drosophila photoreceptors disrupt actin structure at rhabdomeres, as other groups have shown they do in Drosophila and mammalian dendrites. We show this actin regulatory pathway works through the small G protein Rac and the actin nucleating protein Form3. We also find that Form3 has additional functions in photoreceptors, and that loss of Form3 results in the specification of extra photoreceptors in the eye.
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Affiliation(s)
- Annie Vu
- University of San Diego, Department of Biology, 5998 Alcala Park Blvd, SCST 372, San Diego, CA 92110, USA
| | - Tyler Humphries
- University of San Diego, Department of Biology, 5998 Alcala Park Blvd, SCST 372, San Diego, CA 92110, USA
| | - Sean Vogel
- University of San Diego, Department of Biology, 5998 Alcala Park Blvd, SCST 372, San Diego, CA 92110, USA
| | - Adam Haberman
- University of San Diego, Department of Biology, 5998 Alcala Park Blvd, SCST 372, San Diego, CA 92110, USA.
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17
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Bakthavachalu B, Huelsmeier J, Sudhakaran IP, Hillebrand J, Singh A, Petrauskas A, Thiagarajan D, Sankaranarayanan M, Mizoue L, Anderson EN, Pandey UB, Ross E, VijayRaghavan K, Parker R, Ramaswami M. RNP-Granule Assembly via Ataxin-2 Disordered Domains Is Required for Long-Term Memory and Neurodegeneration. Neuron 2018; 98:754-766.e4. [PMID: 29772202 DOI: 10.1016/j.neuron.2018.04.032] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 03/07/2018] [Accepted: 04/23/2018] [Indexed: 02/07/2023]
Abstract
Human Ataxin-2 is implicated in the cause and progression of amyotrophic lateral sclerosis (ALS) and type 2 spinocerebellar ataxia (SCA-2). In Drosophila, a conserved atx2 gene is essential for animal survival as well as for normal RNP-granule assembly, translational control, and long-term habituation. Like its human homolog, Drosophila Ataxin-2 (Atx2) contains polyQ repeats and additional intrinsically disordered regions (IDRs). We demonstrate that Atx2 IDRs, which are capable of mediating liquid-liquid phase transitions in vitro, are essential for efficient formation of neuronal mRNP assemblies in vivo. Remarkably, ΔIDR mutants that lack neuronal RNP granules show normal animal development, survival, and fertility. However, they show defects in long-term memory formation/consolidation as well as in C9ORF72 dipeptide repeat or FUS-induced neurodegeneration. Together, our findings demonstrate (1) that higher-order mRNP assemblies contribute to long-term neuronal plasticity and memory, and (2) that a targeted reduction in RNP-granule formation efficiency can alleviate specific forms of neurodegeneration.
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Affiliation(s)
| | - Joern Huelsmeier
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin-2, Ireland
| | | | - Jens Hillebrand
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin-2, Ireland
| | - Amanjot Singh
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| | - Arnas Petrauskas
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin-2, Ireland
| | | | | | - Laura Mizoue
- Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; HHMI, University of Colorado, Boulder, CO 80309, USA
| | - Eric N Anderson
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Udai Bhan Pandey
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, USA
| | - Eric Ross
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - K VijayRaghavan
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| | - Roy Parker
- Department of Chemistry, University of Colorado, Boulder, CO 80309, USA; HHMI, University of Colorado, Boulder, CO 80309, USA
| | - Mani Ramaswami
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India; Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin-2, Ireland.
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18
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Zhang K, Coyne AN, Lloyd TE. Drosophila models of amyotrophic lateral sclerosis with defects in RNA metabolism. Brain Res 2018; 1693:109-120. [PMID: 29752901 DOI: 10.1016/j.brainres.2018.04.043] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Revised: 04/27/2018] [Accepted: 04/28/2018] [Indexed: 12/12/2022]
Abstract
The fruit fly Drosophila Melanogaster has been widely used to study neurodegenerative diseases. The conservation of nervous system biology coupled with the rapid life cycle and powerful genetic tools in the fly have enabled the identification of novel therapeutic targets that have been validated in vertebrate model systems and human patients. A recent example is in the study of the devastating motor neuron degenerative disease amyotrophic lateral sclerosis (ALS). Mutations in genes that regulate RNA metabolism are a major cause of inherited ALS, and functional analysis of these genes in the fly nervous system has shed light on how mutations cause disease. Importantly, unbiased genetic screens have identified key pathways that contribute to ALS pathogenesis such as nucleocytoplasmic transport and stress granule assembly. In this review, we will discuss the utilization of Drosophila models of ALS with defects in RNA metabolism.
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Affiliation(s)
- Ke Zhang
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Alyssa N Coyne
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Thomas E Lloyd
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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19
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Halbach MV, Gispert S, Stehning T, Damrath E, Walter M, Auburger G. Atxn2 Knockout and CAG42-Knock-in Cerebellum Shows Similarly Dysregulated Expression in Calcium Homeostasis Pathway. THE CEREBELLUM 2017; 16:68-81. [PMID: 26868665 PMCID: PMC5243904 DOI: 10.1007/s12311-016-0762-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited neurodegenerative disorder with preferential affection of Purkinje neurons, which are known as integrators of calcium currents. The expansion of a polyglutamine (polyQ) domain in the RNA-binding protein ataxin-2 (ATXN2) is responsible for this disease, but the causal roles of deficient ATXN2 functions versus aggregation toxicity are still under debate. Here, we studied mouse mutants with Atxn2 knockout (KO) regarding their cerebellar global transcriptome by microarray and RT-qPCR, in comparison with data from Atxn2-CAG42-knock-in (KIN) mouse cerebellum. Global expression downregulations involved lipid and growth signaling pathways in good agreement with previous data. As a novel effect, downregulations of key factors in calcium homeostasis pathways (the transcription factor Rora, transporters Itpr1 and Atp2a2, as well as regulator Inpp5a) were observed in the KO cerebellum, and some of them also occurred subtly early in KIN cerebellum. The ITPR1 protein levels were depleted from soluble fractions of cerebellum in both mutants, but accumulated in its membrane-associated form only in the SCA2 model. Coimmunoprecipitation demonstrated no association of ITPR1 with Q42-expanded or with wild-type ATXN2. These findings provide evidence that the physiological functions and protein interactions of ATXN2 are relevant for calcium-mediated excitation of Purkinje cells as well as for ATXN2-triggered neurotoxicity. These insights may help to understand pathogenesis and tissue specificity in SCA2 and other polyQ ataxias like SCA1, where inositol regulation of calcium flux and RORalpha play a role.
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Affiliation(s)
- Melanie Vanessa Halbach
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Suzana Gispert
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Tanja Stehning
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Ewa Damrath
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Michael Walter
- Institute for Medical Genetics, Eberhard-Karls-University of Tuebingen, 72076, Tuebingen, Germany
| | - Georg Auburger
- Experimental Neurology, Department of Neurology, Goethe University Medical School, Building 89, 3rd floor, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany.
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20
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Velázquez-Pérez L, Tünnerhoff J, Rodríguez-Labrada R, Torres-Vega R, Belardinelli P, Medrano-Montero J, Peña-Acosta A, Canales-Ochoa N, Vázquez-Mojena Y, González-Zaldivar Y, Auburger G, Ziemann U. Corticomuscular Coherence: a Novel Tool to Assess the Pyramidal Tract Dysfunction in Spinocerebellar Ataxia Type 2. THE CEREBELLUM 2017; 16:602-606. [PMID: 27730516 DOI: 10.1007/s12311-016-0827-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Clinical signs of corticospinal tract dysfunction are a common feature of spinocerebellar ataxia type 2 (SCA2) patients. The objective of this study is to assess dysfunction of the corticospinal tract in SCA2 using corticomuscular coherence. Testing corticomuscular coherence and rating of ataxia severity and non-ataxia symptoms were performed in 19 SCA2 patients and 24 age-matched controls. Central motor conduction times (CMCT) to upper and lower right limbs were obtained for the SCA2 group using Transcraneal magnetic stimulation (TMS). SCA2 patients exhibited a significant reduction of corticomuscular coherence for lower limbs, but not for upper limbs. This difference remained significant, even when excluding those individuals with clinical signs of corticospinal tract dysfunction. Corticomuscular coherence for lower limbs correlated inversely with CMCT to tibialis anterior muscle. Corticomuscular coherence could be a valuable electrophysiological tool to assess the corticospinal tract involvement in SCA2, even in the absence of clinical signs of corticospinal tract dysfunction.
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Affiliation(s)
- Luis Velázquez-Pérez
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100.
| | - Johannes Tünnerhoff
- Department Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University Tübingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany
| | - Roberto Rodríguez-Labrada
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100
| | - Reidenis Torres-Vega
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100
| | - Paolo Belardinelli
- Department Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University Tübingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany
| | - Jacqueline Medrano-Montero
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100
| | - Arnoy Peña-Acosta
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100
| | - Nalia Canales-Ochoa
- Department Clinical Neurophysiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Calle Libertad 26, Holguín, Cuba, 80100
| | - Yaimeé Vázquez-Mojena
- Department Molecular Neurobiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba
| | - Yanetza González-Zaldivar
- Department Molecular Neurobiology, Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba
| | - Georg Auburger
- Exp. Neurology, Building 89, Goethe University Medical School, Theodor Stern Kai 7, 60590, Frankfurt am Main, Germany
| | - Ulf Ziemann
- Department Neurology & Stroke, and Hertie Institute for Clinical Brain Research, University Tübingen, Hoppe-Seyler-Straße 3, 72076, Tübingen, Germany.
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21
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Velázquez-Pérez LC, Rodríguez-Labrada R, Fernandez-Ruiz J. Spinocerebellar Ataxia Type 2: Clinicogenetic Aspects, Mechanistic Insights, and Management Approaches. Front Neurol 2017; 8:472. [PMID: 28955296 PMCID: PMC5601978 DOI: 10.3389/fneur.2017.00472] [Citation(s) in RCA: 64] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 08/25/2017] [Indexed: 12/14/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia that occurs as a consequence of abnormal CAG expansions in the ATXN2 gene. Progressive clinical features result from the neurodegeneration of cerebellum and extra-cerebellar structures including the pons, the basal ganglia, and the cerebral cortex. Clinical, electrophysiological, and imaging approaches have been used to characterize the natural history of the disease, allowing its classification into four distinct stages, with special emphasis on the prodromal stage, which is characterized by a plethora of motor and non-motor features. Neuropathological investigations of brain tissue from SCA2 patients reveal a widespread involvement of multiple brain systems, mainly cerebellar and brainstem systems. Recent findings linking ataxin-2 intermediate expansions to other neurodegenerative diseases such as amyotrophic lateral sclerosis have provided insights into the ataxin-2-related toxicity mechanism in neurodegenerative diseases and have raised new ethical challenges to molecular predictive diagnosis of SCA2. No effective neuroprotective therapies are currently available for SCA2 patients, but some therapeutic options such as neurorehabilitation and some emerging neuroprotective drugs have shown palliative benefits.
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Affiliation(s)
- Luis C Velázquez-Pérez
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Medical University of Holguín "Mariana Grajales", Holguín, Cuba
| | - Roberto Rodríguez-Labrada
- Centre for the Research and Rehabilitation of Hereditary Ataxias, Holguín, Cuba.,Physical Culture School, University of Holguin "Oscar Lucero", Holguín, Cuba
| | - Juan Fernandez-Ruiz
- Department of Physiology, Medicine School, UNAM, Cuernavaca, Mexico.,Psychology School, Universidad Veracruzana, Xalapa, Mexico
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22
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Lee J, Yoo E, Lee H, Park K, Hur JH, Lim C. LSM12 and ME31B/DDX6 Define Distinct Modes of Posttranscriptional Regulation by ATAXIN-2 Protein Complex in Drosophila Circadian Pacemaker Neurons. Mol Cell 2017; 66:129-140.e7. [PMID: 28388438 DOI: 10.1016/j.molcel.2017.03.004] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Revised: 01/04/2017] [Accepted: 03/03/2017] [Indexed: 01/12/2023]
Abstract
ATAXIN-2 (ATX2) has been implicated in human neurodegenerative diseases, yet it remains elusive how ATX2 assembles specific protein complexes to execute its physiological roles. Here we employ the posttranscriptional co-activator function of Drosophila ATX2 to demonstrate that LSM12 and ME31B/DDX6 are two ATX2-associating factors crucial for sustaining circadian rhythms. LSM12 acts as a molecular adaptor for the recruitment of TWENTY-FOUR (TYF) to ATX2. The ATX2-LSM12-TYF complex thereby stimulates TYF-dependent translation of the rate-limiting clock gene period (per) to maintain 24 hr periodicity in circadian behaviors. In contrast, ATX2 contributes to NOT1-mediated gene silencing and associates with NOT1 in a ME31B/DDX6-dependent manner. The ME31B/DDX6-NOT1 complex does not affect PER translation but supports high-amplitude behavioral rhythms along with ATX2, indicating a PER-independent clock function of ATX2. Taken together, these data suggest that the ATX2 complex may switch distinct modes of posttranscriptional regulation through its associating factors to control circadian clocks and ATX2-related physiology.
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Affiliation(s)
- Jongbo Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Eunseok Yoo
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Hoyeon Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Keunhee Park
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea
| | - Jin-Hoe Hur
- UNIST-Olympus Biomed Imaging Center, UNIST, Ulsan 44919, Republic of Korea
| | - Chunghun Lim
- School of Life Sciences, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea.
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23
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Auburger G, Sen NE, Meierhofer D, Başak AN, Gitler AD. Efficient Prevention of Neurodegenerative Diseases by Depletion of Starvation Response Factor Ataxin-2. Trends Neurosci 2017; 40:507-516. [DOI: 10.1016/j.tins.2017.06.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 06/09/2017] [Indexed: 12/13/2022]
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24
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Ataxin-2: From RNA Control to Human Health and Disease. Genes (Basel) 2017; 8:genes8060157. [PMID: 28587229 PMCID: PMC5485521 DOI: 10.3390/genes8060157] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/23/2017] [Accepted: 05/31/2017] [Indexed: 12/13/2022] Open
Abstract
RNA-binding proteins play fundamental roles in the regulation of molecular processes critical to cellular and organismal homeostasis. Recent studies have identified the RNA-binding protein Ataxin-2 as a genetic determinant or risk factor for various diseases including spinocerebellar ataxia type II (SCA2) and amyotrophic lateral sclerosis (ALS), amongst others. Here, we first discuss the increasingly wide-ranging molecular functions of Ataxin-2, from the regulation of RNA stability and translation to the repression of deleterious accumulation of the RNA-DNA hybrid-harbouring R-loop structures. We also highlight the broader physiological roles of Ataxin-2 such as in the regulation of cellular metabolism and circadian rhythms. Finally, we discuss insight from clinically focused studies to shed light on the impact of molecular and physiological roles of Ataxin-2 in various human diseases. We anticipate that deciphering the fundamental functions of Ataxin-2 will uncover unique approaches to help cure or control debilitating and lethal human diseases.
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25
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Carmo-Silva S, Nobrega C, Pereira de Almeida L, Cavadas C. Unraveling the Role of Ataxin-2 in Metabolism. Trends Endocrinol Metab 2017; 28:309-318. [PMID: 28117213 DOI: 10.1016/j.tem.2016.12.006] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/14/2016] [Accepted: 12/23/2016] [Indexed: 12/21/2022]
Abstract
Ataxin-2 is a polyglutamine protein implicated in several biological processes such as RNA metabolism and cytoskeleton reorganization. Ataxin-2 is highly expressed in various tissues including the hypothalamus, a brain region that controls food intake and energy balance. Ataxin-2 expression is influenced by nutritional status. Emerging studies discussed here now show that ataxin-2 deficiency correlates with insulin resistance and dyslipidemia, an action mediated via the mTOR pathway, suggesting that ataxin-2 might play key roles in metabolic homeostasis including body weight regulation, insulin sensitivity, and cellular stress responses. In this review we also discuss the relevance of ataxin-2 in the hypothalamic regulation of energy balance, and its potential as a therapeutic target in metabolic disorders such as obesity.
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Affiliation(s)
- Sara Carmo-Silva
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Clevio Nobrega
- Department of Biomedical Sciences and Medicine, Center for Biomedical Research (CBMR), University of Algarve, Faro, Portugal
| | - Luís Pereira de Almeida
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal
| | - Claudia Cavadas
- Center for Neuroscience and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal; Faculty of Pharmacy, University of Coimbra, Coimbra, Portugal.
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26
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Cuello-Almarales DA, Almaguer-Mederos LE, Vázquez-Mojena Y, Almaguer-Gotay D, Zayas-Feria P, Laffita-Mesa JM, González-Zaldívar Y, Aguilera-Rodríguez R, Rodríguez-Estupiñán A, Velázquez-Pérez L. Buccal Cell Micronucleus Frequency Is Significantly Elevated in Patients with Spinocerebellar Ataxia Type 2. Arch Med Res 2017; 48:297-302. [DOI: 10.1016/j.arcmed.2017.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 06/20/2017] [Indexed: 10/18/2022]
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27
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Pfeffer M, Gispert S, Auburger G, Wicht H, Korf HW. Impact of Ataxin-2 knock out on circadian locomotor behavior and PER immunoreaction in the SCN of mice. Chronobiol Int 2016; 34:129-137. [PMID: 27791392 DOI: 10.1080/07420528.2016.1245666] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
In Drosophila melanogaster, Ataxin-2 is a crucial activator of Period and is involved in the control of circadian rhythms. However, in mammals the function of Ataxin-2 is unknown despite its involvement in the inherited neurogenerative disease Spinocerebellar Ataxia type 2 in humans. Therefore, we analyzed locomotor behavior of Atxn2-deficient mice and their WT littermates under entrained- and free-running conditions as well as after experimental jet lag. Furthermore, we compared the PER1 and PER2 immunoreaction (IR) in the SCN. Atxn2-/- mice showed an unstable rhythmicity of locomotor activity, but the level of PER1 and PER2 IR in the SCN did not differ between genotypes.
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Affiliation(s)
- Martina Pfeffer
- a Dr. Senckenbergische Anatomie II, Fachbereich Medizin , Goethe-Universität Frankfurt , Frankfurt am Main , Germany.,b Dr. Senckenbergisches Chronomedizinisches Institut , Goethe-Universität Frankfurt , Frankfurt am Main , Germany
| | - Suzana Gispert
- c Experimental Neurology, Department of Neurology , Goethe-Universität Frankfurt , Frankfurt am Main , Germany
| | - Georg Auburger
- c Experimental Neurology, Department of Neurology , Goethe-Universität Frankfurt , Frankfurt am Main , Germany
| | - Helmut Wicht
- a Dr. Senckenbergische Anatomie II, Fachbereich Medizin , Goethe-Universität Frankfurt , Frankfurt am Main , Germany
| | - Horst-Werner Korf
- a Dr. Senckenbergische Anatomie II, Fachbereich Medizin , Goethe-Universität Frankfurt , Frankfurt am Main , Germany.,b Dr. Senckenbergisches Chronomedizinisches Institut , Goethe-Universität Frankfurt , Frankfurt am Main , Germany
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28
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Vianna MCB, Poleto DC, Gomes PF, Valente V, Paçó‐Larson ML. Drosophila ataxin-2 gene encodes two differentially expressed isoforms and its function in larval fat body is crucial for development of peripheral tissues. FEBS Open Bio 2016; 6:1040-1053. [PMID: 27833845 PMCID: PMC5095142 DOI: 10.1002/2211-5463.12124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 08/02/2016] [Accepted: 09/01/2016] [Indexed: 01/28/2023] Open
Abstract
Different isoforms of ataxin‐2 are predicted in Drosophila and may underlie different cellular processes. Here, we validated the isoforms B and C of Drosophila ataxin‐2 locus (dAtx2), which we found to be expressed in various tissues and at different levels during development. dAtx2‐B mRNA was detected at low amounts during all developmental stages, whereas dAtx2‐C mRNA levels increase by eightfold from L3 to pupal–adult stages. Higher amounts of dAtx2‐B protein were detected in embryos, while dAtx2‐C protein was also expressed in higher levels in pupal–adult stages, indicating post‐transcriptional control for isoform B and transcription induction for isoform C, respectively. Moreover, in the fat body of L3 larvae dAtx2‐C, but not dAtx2‐B, accumulates in cytoplasmic foci that colocalize with sec23, a marker of endoplasmic reticulum exit sites (ERES). Interestingly, animals subjected to selective knockdown of dAtx2 in the larval fat body do not complete metamorphosis and die at the third larval stage or early puparium. Additionally, larvae knocked down for dAtx2, grown at 29 °C, are significantly smaller than control animals due to reduction in DNA replication and cell growth, which are consistent with the decreased levels of phosphorylated‐AKT observed in the fat body. Based on the localization of ataxin‐2 (dAtx2‐C) in ERESs, and on the phenotypes observed by dAtx2 knockdown in the larval fat body, we speculate a possible role for this protein in processes that regulate ERES formation. These data provide new insights into the biological function of ataxin‐2 with potential relevance to neurodegenerative diseases.
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Affiliation(s)
- Murilo Carlos Bizam Vianna
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
- Present address: Center of Biological SciencesState University of LondrinaCampus Universitário, LondrinaPR 86057‐97Brazil
| | - Deise Cristina Poleto
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
| | - Paula Fernanda Gomes
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
| | - Valéria Valente
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
- Present address: Department of Clinical AnalysisFaculty of Pharmaceutical Sciences of AraraquaraUniversity of São Paulo State (UNESP)R. Expedicionários do Brasil, 1628, AraraquaraSP 14801‐902Brazil
| | - Maria Luisa Paçó‐Larson
- Department of Cellular and Molecular BiologyRibeirão Preto School of MedicineUniversity of São PauloRibeirão PretoSPBrazil
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29
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Gnazzo MM, Uhlemann EME, Villarreal AR, Shirayama M, Dominguez EG, Skop AR. The RNA-binding protein ATX-2 regulates cytokinesis through PAR-5 and ZEN-4. Mol Biol Cell 2016; 27:3052-3064. [PMID: 27559134 PMCID: PMC5063614 DOI: 10.1091/mbc.e16-04-0219] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Accepted: 08/17/2016] [Indexed: 12/15/2022] Open
Abstract
The mechanisms that mediate the temporal and spatial recruitment of cell division factors to the spindle midzone and midbody remain unclear. Cell division is regulated by the conserved RNA-binding protein, ATX-2/Ataxin-2, which facilitates the targeting of ZEN-4 to the spindle midzone by mediating PAR-5. The spindle midzone harbors both microtubules and proteins necessary for furrow formation and the completion of cytokinesis. However, the mechanisms that mediate the temporal and spatial recruitment of cell division factors to the spindle midzone and midbody remain unclear. Here we describe a mechanism governed by the conserved RNA-binding protein ATX-2/Ataxin-2, which targets and maintains ZEN-4 at the spindle midzone. ATX-2 does this by regulating the amount of PAR-5 at mitotic structures, particularly the spindle, centrosomes, and midbody. Preventing ATX-2 function leads to elevated levels of PAR-5, enhanced chromatin and centrosome localization of PAR-5–GFP, and ultimately a reduction of ZEN-4–GFP at the spindle midzone. Codepletion of ATX-2 and PAR-5 rescued the localization of ZEN-4 at the spindle midzone, indicating that ATX-2 mediates the localization of ZEN-4 upstream of PAR-5. We provide the first direct evidence that ATX-2 is necessary for cytokinesis and suggest a model in which ATX-2 facilitates the targeting of ZEN-4 to the spindle midzone by mediating the posttranscriptional regulation of PAR-5.
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Affiliation(s)
- Megan M Gnazzo
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Eva-Maria E Uhlemann
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Alex R Villarreal
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706
| | - Masaki Shirayama
- Program in Molecular Medicine, RNA Therapeutics Institute, and Howard Hughes Medical Institute, University of Massachusetts Medical School, Worcester, MA 01605
| | - Eddie G Dominguez
- Department of Medicine, University of Wisconsin-Madison, Madison, WI 53705
| | - Ahna R Skop
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI 53706
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30
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Bar DZ, Charar C, Dorfman J, Yadid T, Tafforeau L, Lafontaine DLJ, Gruenbaum Y. Cell size and fat content of dietary-restricted Caenorhabditis elegans are regulated by ATX-2, an mTOR repressor. Proc Natl Acad Sci U S A 2016; 113:E4620-9. [PMID: 27457958 PMCID: PMC4987808 DOI: 10.1073/pnas.1512156113] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Dietary restriction (DR) is a metabolic intervention that extends the lifespan of multiple species, including yeast, flies, nematodes, rodents, and, arguably, rhesus monkeys and humans. Hallmarks of lifelong DR are reductions in body size, fecundity, and fat accumulation, as well as slower development. We have identified atx-2, the Caenorhabditis elegans homolog of the human ATXN2L and ATXN2 genes, as the regulator of these multiple DR phenotypes. Down-regulation of atx-2 increases the body size, cell size, and fat content of dietary-restricted animals and speeds animal development, whereas overexpression of atx-2 is sufficient to reduce the body size and brood size of wild-type animals. atx-2 regulates the mechanistic target of rapamycin (mTOR) pathway, downstream of AMP-activated protein kinase (AMPK) and upstream of ribosomal protein S6 kinase and mTOR complex 1 (TORC1), by its direct association with Rab GDP dissociation inhibitor β, which likely regulates RHEB shuttling between GDP-bound and GTP-bound forms. Taken together, this work identifies a previously unknown mechanism regulating multiple aspects of DR, as well as unknown regulators of the mTOR pathway. They also extend our understanding of diet-dependent growth retardation, and offers a potential mechanism to treat obesity.
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Affiliation(s)
- Daniel Z Bar
- Department of Genetics, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel
| | - Chayki Charar
- Department of Genetics, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel
| | - Jehudith Dorfman
- Department of Genetics, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel
| | - Tam Yadid
- Department of Genetics, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel
| | - Lionel Tafforeau
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S.-FNRS), Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles (ULB), BioPark Campus, Gosselies B-6041, Belgium
| | - Denis L J Lafontaine
- RNA Molecular Biology, Fonds de la Recherche Scientifique (F.R.S.-FNRS), Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles (ULB), BioPark Campus, Gosselies B-6041, Belgium
| | - Yosef Gruenbaum
- Department of Genetics, Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem 9190401, Israel;
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Mark MD, Schwitalla JC, Groemmke M, Herlitze S. Keeping Our Calcium in Balance to Maintain Our Balance. Biochem Biophys Res Commun 2016; 483:1040-1050. [PMID: 27392710 DOI: 10.1016/j.bbrc.2016.07.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 07/04/2016] [Indexed: 01/13/2023]
Abstract
Calcium is a key signaling molecule and ion involved in a variety of diverse processes in our central nervous system (CNS) which include gene expression, synaptic transmission and plasticity, neuronal excitability and cell maintenance. Proper control of calcium signaling is not only vital for neuronal physiology but also cell survival. Mutations in fundamental channels, transporters and second messenger proteins involved in orchestrating the balance of our calcium homeostasis can lead to severe neurodegenerative disorders, such as Spinocerebellar (SCA) and Episodic (EA) ataxias. Hereditary ataxias make up a remarkably diverse group of neurological disorders clinically characterized by gait ataxia, nystagmus, dysarthria, trunk and limb ataxia and often atrophy of the cerebellum. The largest family of hereditary ataxias is SCAs which consists of a growing family of 42 members. A relatively smaller family of 8 members compose the EAs. The gene mutations responsible for half of the EA members and over 35 of the SCA subtypes have been identified, and several have been found to be responsible for cerebellar atrophy, abnormal intracellular calcium levels, dysregulation of Purkinje cell pacemaking, altered cerebellar synaptic transmission and/or ataxia in mouse models. Although the genetic diversity and affected cellular pathways of hereditary ataxias are broad, one common theme amongst these genes is their effects on maintaining calcium balance in primarily the cerebellum. There is emerging evidence that the pathogenesis of hereditary ataxias may be caused by imbalances in intracellular calcium due to genetic mutations in calcium-mediating proteins. In this review we will discuss the current evidence supporting the role of deranged calcium as the culprit to neurodegenerative diseases with a primary focus on SCAs and EAs.
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Affiliation(s)
- Melanie D Mark
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany.
| | - Jan Claudius Schwitalla
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Michelle Groemmke
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
| | - Stefan Herlitze
- Department of Zoology and Neurobiology, ND7/31, Ruhr University Bochum, Universitätsstr. 150, D-44780 Bochum, Germany
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Krench M, Cho RW, Littleton JT. A Drosophila model of Huntington disease-like 2 exhibits nuclear toxicity and distinct pathogenic mechanisms from Huntington disease. Hum Mol Genet 2016; 25:3164-3177. [PMID: 27288455 DOI: 10.1093/hmg/ddw166] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/22/2016] [Accepted: 05/20/2016] [Indexed: 12/23/2022] Open
Abstract
Huntington disease-like 2 (HDL2) and Huntington disease (HD) are adult-onset neurodegenerative diseases characterized by movement disorders, psychiatric disturbances and cognitive decline. Brain tissue from HD and HDL2 patients shows degeneration of the striatum and ubiquitinated inclusions immunoreactive for polyglutamine (polyQ) antibodies. Despite these similarities, the diseases result from different genetic mutations. HD is caused by a CAG repeat expansion in the huntingtin (HTT) gene, while HDL2 results from an expansion at the junctophilin 3 (JPH3) locus. Recent evidence indicates that the HDL2 expansion may give rise to a toxic polyQ protein translated from an antisense mRNA derived from the JPH3 locus. To investigate this hypothesis, we generated and characterized a Drosophila HDL2 model and compared it with a previously established HD model. We find that neuronal expression of HDL2-Q15 is not toxic, while the expression of an expanded HDL2-Q138 protein is lethal. HDL2-Q138 forms large nuclear aggregates, with only smaller puncta observed in the cytoplasm. This is in contrast to what is observed in a Drosophila model of HD, where polyQ aggregates localize exclusively to the cytoplasm. Altering localization of HLD2 with the addition of a nuclear localization or nuclear export sequence demonstrates that nuclear accumulation is required for toxicity in the Drosophila HDL2 model. Directing HDL2-Q138 to the nucleus exacerbates toxicity in multiple tissue types, while confining HDL2-Q138 to the cytoplasm restores viability to control levels. We conclude that while HD and HDL2 have similar clinical profiles, distinct pathogenic mechanisms are likely to drive toxicity in Drosophila models of these disorders.
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Affiliation(s)
- Megan Krench
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences
| | - Richard W Cho
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences.,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - J Troy Littleton
- The Picower Institute for Learning and Memory, Department of Brain and Cognitive Sciences .,Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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McGurk L, Berson A, Bonini NM. Drosophila as an In Vivo Model for Human Neurodegenerative Disease. Genetics 2015; 201:377-402. [PMID: 26447127 PMCID: PMC4596656 DOI: 10.1534/genetics.115.179457] [Citation(s) in RCA: 199] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Accepted: 08/19/2015] [Indexed: 12/13/2022] Open
Abstract
With the increase in the ageing population, neurodegenerative disease is devastating to families and poses a huge burden on society. The brain and spinal cord are extraordinarily complex: they consist of a highly organized network of neuronal and support cells that communicate in a highly specialized manner. One approach to tackling problems of such complexity is to address the scientific questions in simpler, yet analogous, systems. The fruit fly, Drosophila melanogaster, has been proven tremendously valuable as a model organism, enabling many major discoveries in neuroscientific disease research. The plethora of genetic tools available in Drosophila allows for exquisite targeted manipulation of the genome. Due to its relatively short lifespan, complex questions of brain function can be addressed more rapidly than in other model organisms, such as the mouse. Here we discuss features of the fly as a model for human neurodegenerative disease. There are many distinct fly models for a range of neurodegenerative diseases; we focus on select studies from models of polyglutamine disease and amyotrophic lateral sclerosis that illustrate the type and range of insights that can be gleaned. In discussion of these models, we underscore strengths of the fly in providing understanding into mechanisms and pathways, as a foundation for translational and therapeutic research.
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Affiliation(s)
- Leeanne McGurk
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Amit Berson
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Nancy M Bonini
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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Both ubiquitin ligases FBXW8 and PARK2 are sequestrated into insolubility by ATXN2 PolyQ expansions, but only FBXW8 expression is dysregulated. PLoS One 2015; 10:e0121089. [PMID: 25790475 PMCID: PMC4366354 DOI: 10.1371/journal.pone.0121089] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 01/27/2015] [Indexed: 12/13/2022] Open
Abstract
The involvement of the ubiquitin-proteasome system (UPS) in the course of various age-associated neurodegenerative diseases is well established. The single RING finger type E3 ubiquitin-protein ligase PARK2 is mutated in a Parkinson’s disease (PD) variant and was found to interact with ATXN2, a protein where polyglutamine expansions cause Spinocerebellar ataxia type 2 (SCA2) or increase the risk for Levodopa-responsive PD and for the motor neuron disease Amyotrophic lateral sclerosis (ALS). We previously reported evidence for a transcriptional induction of the multi-subunit RING finger Skp1/Cul/F-box (SCF) type E3 ubiquitin-protein ligase complex component FBXW8 in global microarray profiling of ATXN2-expansion mouse cerebellum and demonstrated its role for ATXN2 degradation in vitro. Now, we documented co-localization in vitro and co-immunoprecipitations both in vitro and in vivo, which indicate associations of FBXW8 with ATXN2 and PARK2. Both FBXW8 and PARK2 proteins are driven into insolubility by expanded ATXN2. Whereas the FBXW8 transcript upregulation by ATXN2- expansion was confirmed also in qPCR of skin fibroblasts and blood samples of SCA2 patients, a FBXW8 expression dysregulation was not observed in ATXN2-deficient mice, nor was a PARK2 transcript dysregulation observed in any samples. Jointly, all available data suggest that the degradation of wildtype and mutant ATXN2 is dependent on FBXW8, and that ATXN2 accumulation selectively modulates FBXW8 levels, while PARK2 might act indirectly through FBXW8. The effects of ATXN2-expansions on FBXW8 expression in peripheral tissues like blood may become useful for clinical diagnostics.
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Taking a risk: a therapeutic focus on ataxin-2 in amyotrophic lateral sclerosis? Trends Mol Med 2014; 20:25-35. [DOI: 10.1016/j.molmed.2013.09.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/03/2013] [Accepted: 09/17/2013] [Indexed: 12/12/2022]
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Lim C, Allada R. ATAXIN-2 activates PERIOD translation to sustain circadian rhythms in Drosophila. Science 2013; 340:875-9. [PMID: 23687047 DOI: 10.1126/science.1234785] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Evidence for transcriptional feedback in circadian timekeeping is abundant, yet little is known about the mechanisms underlying translational control. We found that ATAXIN-2 (ATX2), an RNA-associated protein involved in neurodegenerative disease, is a translational activator of the rate-limiting clock component PERIOD (PER) in Drosophila. ATX2 specifically interacted with TWENTY-FOUR (TYF), an activator of PER translation. RNA interference-mediated depletion of Atx2 or the expression of a mutant ATX2 protein that does not associate with polyadenylate-binding protein (PABP) suppressed behavioral rhythms and decreased abundance of PER. Although ATX2 can repress translation, depletion of Atx2 from Drosophila S2 cells inhibited translational activation by RNA-tethered TYF and disrupted the association between TYF and PABP. Thus, ATX2 coordinates an active translation complex important for PER expression and circadian rhythms.
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Affiliation(s)
- Chunghun Lim
- Department of Neurobiology, Northwestern University, Evanston, IL 60208, USA
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Transcriptome Profiling Following Neuronal and Glial Expression of ALS-Linked SOD1 in Drosophila. G3-GENES GENOMES GENETICS 2013; 3:695-708. [PMID: 23550139 PMCID: PMC3618356 DOI: 10.1534/g3.113.005850] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) generally is a late-onset neurodegenerative disease. Mutations in the Cu/Zn superoxide dismutase 1 (SOD1) gene account for approximately 20% of familial ALS and 2% of all ALS cases. Although a number of hypotheses have been proposed to explain mutant SOD1 toxicity, the molecular mechanisms of the disease remain unclear. SOD1-linked ALS is thought to function in a non-cell-autonomous manner such that motoneurons are critical for the onset, and glia contribute to progression of the disease. Recently, it has been shown in Drosophila melanogaster that expression of human SOD1 in a subset of neuronal cells causes synaptic transmission defects, modified motor function, and altered sensitivity to compounds that induce oxidative stress. Here we used the Gal4-UAS (Upstream Activation Sequence) system to further characterize flies expressing wild-type Drosophila SOD1 (dSOD1) and the mutant human SOD1G85R (G85R) allele in motoneurons and glia. Cell-specific expression of both dSOD1 and G85R was found to influence lifespan, affect sensitivity to hydrogen peroxide, and alter lipid peroxidation levels. To better understand the genetic consequences of G85R expression in motoneurons and glia, we conducted microarray analysis of both young flies (5 days old) and old flies (45 days old) expressing G85R selectively in motoneurons or glia and concurrently in motoneurons and glia. Results from this microarray experiment identified candidate genes for further investigation and may help elucidate the individual and combined contributions of motoneurons and glia in ALS.
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Kasumu A, Bezprozvanny I. Deranged calcium signaling in Purkinje cells and pathogenesis in spinocerebellar ataxia 2 (SCA2) and other ataxias. THE CEREBELLUM 2012; 11:630-9. [PMID: 20480274 DOI: 10.1007/s12311-010-0182-9] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Spinocerebellar ataxias (SCAs) constitute a heterogeneous group of more than 30 autosomal-dominant genetic and neurodegenerative disorders. SCAs are generally characterized by progressive ataxia and cerebellar atrophy. Although all SCA patients present with the phenotypic overlap of cerebellar atrophy and ataxia, 17 different gene loci have so far been implicated as culprits in these SCAs. It is not currently understood how mutations in these 17 proteins lead to the cerebellar atrophy and ataxia. Several pathogenic mechanisms have been studied in SCAs but there is yet to be a promising target for successful treatment of SCAs. Emerging research suggests that a fundamental cellular signaling pathway is disrupted by a majority of these mutated genes, which could explain the characteristic death of Purkinje cells, cerebellar atrophy, and ataxia that occur in many SCAs. We propose that mutations in SCA genes cause disruptions in multiple cellular pathways but the characteristic SCA pathogenesis does not begin until calcium signaling pathways are disrupted in cerebellar Purkinje cells either as a result of an excitotoxic increase or a compensatory suppression of calcium signaling. We argue that disruptions in Purkinje cell calcium signaling lead to initial cerebellar dysfunction and ataxic sympoms and eventually proceed to Purkinje cell death. Here, we discuss a calcium hypothesis of Purkinje cell neurodegeneration in SCAs by primarily focusing on an example of spinocerebellar ataxia 2 (SCA2). We will also present evidence linking deranged calcium signaling to the pathogenesis of other SCAs (SCA1, 3, 5, 6, 14, 15/16) that lead to significant Purkinje cell dysfunction and loss in patients.
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Affiliation(s)
- Adebimpe Kasumu
- Department of Physiology, UT Southwestern Medical Center at Dallas, Texas, USA
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Hansen ST, Meera P, Otis TS, Pulst SM. Changes in Purkinje cell firing and gene expression precede behavioral pathology in a mouse model of SCA2. Hum Mol Genet 2012; 22:271-83. [PMID: 23087021 PMCID: PMC3526159 DOI: 10.1093/hmg/dds427] [Citation(s) in RCA: 123] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominantly inherited disorder, which is caused by a pathological expansion of a polyglutamine (polyQ) tract in the coding region of the ATXN2 gene. Like other ataxias, SCA2 most overtly affects Purkinje cells (PCs) in the cerebellum. Using a transgenic mouse model expressing a full-length ATXN2Q127-complementary DNA under control of the Pcp2 promoter (a PC-specific promoter), we examined the time course of behavioral, morphologic, biochemical and physiological changes with particular attention to PC firing in the cerebellar slice. Although motor performance began to deteriorate at 8 weeks of age, reductions in PC number were not seen until after 12 weeks. Decreases in the PC firing frequency first showed at 6 weeks and paralleled deterioration of motor performance with progression of disease. Transcription changes in several PC-specific genes such as Calb1 and Pcp2 mirrored the time course of changes in PC physiology with calbindin-28 K changes showing the first small, but significant decreases at 4 weeks. These results emphasize that in this model of SCA2, physiological and behavioral phenotypes precede morphological changes by several weeks and provide a rationale for future studies examining the effects of restoration of firing frequency on motor function and prevention of future loss of PCs.
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Magaña JJ, Velázquez-Pérez L, Cisneros B. Spinocerebellar ataxia type 2: clinical presentation, molecular mechanisms, and therapeutic perspectives. Mol Neurobiol 2012; 47:90-104. [PMID: 22996397 DOI: 10.1007/s12035-012-8348-8] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 09/05/2012] [Indexed: 12/13/2022]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant genetic disease characterized by cerebellar dysfunction associated with slow saccades, early hyporeflexia, severe tremor of postural or action type, peripheral neuropathy, cognitive disorders, and other multisystemic features. SCA2, one of the most common ataxias worldwide, is caused by the expansion of a CAG triplet repeat located in the N-terminal coding region of the ATXN2 gene, which results in the incorporation of a segment of polyglutamines in the mutant protein, being longer expansions associated with earlier onset and more sever disease in subsequent generations. In this review, we offer a detailed description of the clinical manifestations of SCA2 and compile the experimental evidence showing the participation of ataxin-2 in crucial cellular processes, including messenger RNA maturation and translation, and endocytosis. In addition, we discuss in the light of present data the potential molecular mechanisms underlying SCA2 pathogenesis. The mutant protein exhibits a toxic gain of function that is mainly attributed to the generation of neuronal inclusions of phosphorylated and/or proteolytic cleaved mutant ataxin-2, which might alter normal ataxin-2 function, leading to cell dysfunction and death of target cells. In the final part of this review, we discuss the perspectives of development of therapeutic strategies for SCA2. Based on previous experience with other polyglutamine disorders and considering the molecular basis of SCA2 pathogenesis, a nuclei-acid-based strategy focused on the specific silencing of the dominant disease allele that preserves the expression of the wild-type allele is highly desirable and might prevent toxic neurodegenerative sequelae.
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Affiliation(s)
- J J Magaña
- Department of Genetics, National Rehabilitation Institute (INR), Mexico City, Mexico
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Bomtorin AD, Barchuk AR, Moda LM, Simoes ZLP. Hox gene expression leads to differential hind leg development between honeybee castes. PLoS One 2012; 7:e40111. [PMID: 22848371 PMCID: PMC3405112 DOI: 10.1371/journal.pone.0040111] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Accepted: 06/01/2012] [Indexed: 12/29/2022] Open
Abstract
Beyond the physiological and behavioural, differences in appendage morphology between the workers and queens of Apis mellifera are pre-eminent. The hind legs of workers, which are highly specialized pollinators, deserve special attention. The hind tibia of worker has an expanded bristle-free region used for carrying pollen and propolis, the corbicula. In queens this structure is absent. Although the morphological differences are well characterized, the genetic inputs driving the development of this alternative morphology remain unknown. Leg phenotype determination takes place between the fourth and fifth larval instar and herein we show that the morphogenesis is completed at brown-eyed pupa. Using results from the hybridization of whole genome-based oligonucleotide arrays with RNA samples from hind leg imaginal discs of pre-pupal honeybees of both castes we present a list of 200 differentially expressed genes. Notably, there are castes preferentially expressed cuticular protein genes and members of the P450 family. We also provide results of qPCR analyses determining the developmental transcription profiles of eight selected genes, including abdominal-A, distal-less and ultrabithorax (Ubx), whose roles in leg development have been previously demonstrated in other insect models. Ubx expression in workers hind leg is approximately 25 times higher than in queens. Finally, immunohistochemistry assays show that Ubx localization during hind leg development resembles the bristles localization in the tibia/basitarsus of the adult legs in both castes. Our data strongly indicate that the development of the hind legs diphenism characteristic of this corbiculate species is driven by a set of caste-preferentially expressed genes, such as those encoding cuticular protein genes, P450 and Hox proteins, in response to the naturally different diets offered to honeybees during the larval period.
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Affiliation(s)
- Ana Durvalina Bomtorin
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Angel Roberto Barchuk
- Departamento de Biologia Celular, Tecidual e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas, Alfenas, Minas Gerais, Brazil
| | - Livia Maria Moda
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Zila Luz Paulino Simoes
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, São Paulo, Brazil
- * E-mail:
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Rincon-Limas DE, Jensen K, Fernandez-Funez P. Drosophila models of proteinopathies: the little fly that could. Curr Pharm Des 2012; 18:1108-22. [PMID: 22288402 PMCID: PMC3290773 DOI: 10.2174/138161212799315894] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2011] [Accepted: 12/19/2011] [Indexed: 02/08/2023]
Abstract
Alzheimer’s, Parkinson’s, and Huntington’s disease are complex neurodegenerative conditions with high prevalence characterized by protein misfolding and deposition in the brain. Considerable progress has been made in the last two decades in identifying the genes and proteins responsible for several human ‘proteinopathies’. A wide variety of wild type and mutant proteins associated with neurodegenerative conditions are structurally unstable, misfolded, and acquire conformations rich in ß-sheets (ß-state). These conformers form highly toxic self-assemblies that kill the neurons in stereotypical patterns. Unfortunately, the detailed understanding of the molecular and cellular perturbations caused by these proteins has not produced a single disease-modifying therapy. More than a decade ago, several groups demonstrated that human proteinopathies reproduce critical features of the disease in transgenic flies, including protein misfolding, aggregation, and neurotoxicity. These initial reports led to an explosion of research that has contributed to a better understanding of the molecular mechanisms regulating conformational dynamics and neurotoxic cascades. To remain relevant in this competitive environment, Drosophila models will need to expand their flexible, innovative, and multidisciplinary approaches to find new discoveries and translational applications.
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Affiliation(s)
- Diego E Rincon-Limas
- Department of Neurology, McKnight Brain Institute, University of Florida, Gainesville, FL 32610-0236, USA.
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Abstract
Ataxia is a neurological disorder characterized by loss of control of body movements. Spinocerebellar ataxia (SCA), previously known as autosomal dominant cerebellar ataxia, is a biologically robust group of close to 30 progressive neurodegenerative diseases. Six SCAs, including the more prevalent SCA1, SCA2, SCA3, and SCA6 along with SCA7 and SCA17 are caused by expansion of a CAG repeat that encodes a polyglutamine tract in the affected protein. How the mutated proteins in these polyglutamine SCAs cause disease is highly debated. Recent work suggests that the mutated protein contributes to pathogenesis within the context of its “normal” cellular function. Thus, understanding the cellular function of these proteins could aid in the development of therapeutics.
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Affiliation(s)
- Harry T Orr
- Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
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Affiliation(s)
- Georg W J Auburger
- Section Molecular Neurogenetics, Department of Neurology, Johann Wolfgang Goeche University Medical School, Frankfurt/Main, Germany.
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Velázquez-Pérez L, Rodríguez-Labrada R, García-Rodríguez JC, Almaguer-Mederos LE, Cruz-Mariño T, Laffita-Mesa JM. A comprehensive review of spinocerebellar ataxia type 2 in Cuba. THE CEREBELLUM 2011; 10:184-98. [PMID: 21399888 DOI: 10.1007/s12311-011-0265-2] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant cerebellar ataxia characterized by a progressive cerebellar syndrome associated to saccadic slowing, peripheral neuropathy, cognitive disorders, and other multisystem features. SCA2 is caused by the abnormal expansion of cytosine-adenine-guanine triplet repeats in the encoding region of the ATXN2 gene and therefore the expression of toxic polyglutamine expansions in the ataxin 2 protein, which cause progressive neuronal death of Purkinje cells in the cerebellum and several pontine, mesencephalic, and thalamic neurons among other cells. Worldwide, SCA2 is the second most frequent type of spinocerebellar ataxia, only surpassed by SCA3. Nevertheless, in Holguin, Cuba, the disease reaches the highest prevalence, resulting from a putative foundational effect. This review discusses the most important advances in the genotypical and phenotypical studies of SCA2, highlighting the comprehensive characterization reached in Cuba through clinical, neuroepidemiological, neurochemical, and neurophysiological evaluation of SCA2 patients and pre-symptomatic subjects, which has allowed the identification of new disease biomarkers and therapeutical opportunities. These findings provide guidelines, from a Cuban viewpoint, for the clinical management of the disease, its diagnosis, genetic counseling, and therapeutical options through rehabilitative therapy and/or pharmacological options.
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Affiliation(s)
- Luis Velázquez-Pérez
- Centro para la Investigación y Rehabilitación de Ataxias Hereditarias, 80100, Holguín, Cuba.
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The Ataxin-2 protein is required for microRNA function and synapse-specific long-term olfactory habituation. Proc Natl Acad Sci U S A 2011; 108:E655-62. [PMID: 21795609 DOI: 10.1073/pnas.1107198108] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Local control of mRNA translation has been proposed as a mechanism for regulating synapse-specific plasticity associated with long-term memory. We show here that glomerulus-selective plasticity of Drosophila multiglomerular local interneurons observed during long-term olfactory habituation (LTH) requires the Ataxin-2 protein (Atx2) to function in uniglomerular projection neurons (PNs) postsynaptic to local interneurons (LNs). PN-selective knockdown of Atx2 selectively blocks LTH to odorants to which the PN responds and in addition selectively blocks LTH-associated structural and functional plasticity in odorant-responsive glomeruli. Atx2 has been shown previously to bind DEAD box helicases of the Me31B family, proteins associated with Argonaute (Ago) and microRNA (miRNA) function. Robust transdominant interactions of atx2 with me31B and ago1 indicate that Atx2 functions with miRNA-pathway components for LTH and associated synaptic plasticity. Further direct experiments show that Atx2 is required for miRNA-mediated repression of several translational reporters in vivo. Together, these observations (i) show that Atx2 and miRNA components regulate synapse-specific long-term plasticity in vivo; (ii) identify Atx2 as a component of the miRNA pathway; and (iii) provide insight into the biological function of Atx2 that is of potential relevance to spinocerebellar ataxia and neurodegenerative disease.
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Hussman JP, Chung RH, Griswold AJ, Jaworski JM, Salyakina D, Ma D, Konidari I, Whitehead PL, Vance JM, Martin ER, Cuccaro ML, Gilbert JR, Haines JL, Pericak-Vance MA. A noise-reduction GWAS analysis implicates altered regulation of neurite outgrowth and guidance in autism. Mol Autism 2011; 2:1. [PMID: 21247446 PMCID: PMC3035032 DOI: 10.1186/2040-2392-2-1] [Citation(s) in RCA: 123] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2010] [Accepted: 01/19/2011] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Genome-wide Association Studies (GWAS) have proved invaluable for the identification of disease susceptibility genes. However, the prioritization of candidate genes and regions for follow-up studies often proves difficult due to false-positive associations caused by statistical noise and multiple-testing. In order to address this issue, we propose the novel GWAS noise reduction (GWAS-NR) method as a way to increase the power to detect true associations in GWAS, particularly in complex diseases such as autism. METHODS GWAS-NR utilizes a linear filter to identify genomic regions demonstrating correlation among association signals in multiple datasets. We used computer simulations to assess the ability of GWAS-NR to detect association against the commonly used joint analysis and Fisher's methods. Furthermore, we applied GWAS-NR to a family-based autism GWAS of 597 families and a second existing autism GWAS of 696 families from the Autism Genetic Resource Exchange (AGRE) to arrive at a compendium of autism candidate genes. These genes were manually annotated and classified by a literature review and functional grouping in order to reveal biological pathways which might contribute to autism aetiology. RESULTS Computer simulations indicate that GWAS-NR achieves a significantly higher classification rate for true positive association signals than either the joint analysis or Fisher's methods and that it can also achieve this when there is imperfect marker overlap across datasets or when the closest disease-related polymorphism is not directly typed. In two autism datasets, GWAS-NR analysis resulted in 1535 significant linkage disequilibrium (LD) blocks overlapping 431 unique reference sequencing (RefSeq) genes. Moreover, we identified the nearest RefSeq gene to the non-gene overlapping LD blocks, producing a final candidate set of 860 genes. Functional categorization of these implicated genes indicates that a significant proportion of them cooperate in a coherent pathway that regulates the directional protrusion of axons and dendrites to their appropriate synaptic targets. CONCLUSIONS As statistical noise is likely to particularly affect studies of complex disorders, where genetic heterogeneity or interaction between genes may confound the ability to detect association, GWAS-NR offers a powerful method for prioritizing regions for follow-up studies. Applying this method to autism datasets, GWAS-NR analysis indicates that a large subset of genes involved in the outgrowth and guidance of axons and dendrites is implicated in the aetiology of autism.
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Affiliation(s)
| | - Ren-Hua Chung
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Anthony J Griswold
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - James M Jaworski
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Daria Salyakina
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Deqiong Ma
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Ioanna Konidari
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Patrice L Whitehead
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Jeffery M Vance
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Eden R Martin
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Michael L Cuccaro
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - John R Gilbert
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
| | - Jonathan L Haines
- Vanderbilt Center for Human Genetics Research, Vanderbilt University, Nashville, TN, USA
| | - Margaret A Pericak-Vance
- John P. Hussman Institute for Human Genomics, University of Miami, 1501 NW 10th Avenue, Miami, FL 33136, USA
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Bezprozvanny I. Role of inositol 1,4,5-trisphosphate receptors in pathogenesis of Huntington's disease and spinocerebellar ataxias. Neurochem Res 2011; 36:1186-97. [PMID: 21210219 DOI: 10.1007/s11064-010-0393-y] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/27/2010] [Indexed: 11/28/2022]
Abstract
Huntington's disease (HD) and spinocerebellar ataxias (SCAs) are autosomal-dominant neurodegenerative disorders. HD is caused by polyglutamine (polyQ) expansion in the amino-terminal region of a protein huntingtin (Htt) and primarily affects medium spiny striatal neurons (MSN). Many SCAs are caused by polyQ-expansion in ataxin proteins and primarily affect cerebellar Purkinje cells. The reasons for neuronal dysfunction and death in HD and SCAs remain poorly understood and no cure is available for the patients. Our laboratory discovered that mutant huntingtin, ataxin-2 and ataxin-3 proteins specifically bind to the carboxy-terminal region of the type 1 inositol 1,4,5-trisphosphate receptor (IP(3)R1), an intracellular Ca(2+) release channel. Moreover, we found that association of mutant huntingtin or ataxins with IP(3)R1 causes sensitization of IP(3)R1 to activation by IP(3) in planar lipid bilayers and in neuronal cells. These results suggested that deranged neuronal Ca(2+) signaling might play an important role in pathogenesis of HD, SCA2 and SCA3. In support of this idea, we demonstrated a connection between abnormal Ca(2+) signaling and neuronal cell death in experiments with HD, SCA2 and SCA3 transgenic mouse models. Additional data in the literature indicate that abnormal neuronal Ca(2+) signaling may also play an important role in pathogenesis of SCAl, SCA5, SCA6, SCA14 and SCA15/16. Based on these results I propose that IP(3)R and other Ca(2+) signaling proteins should be considered as potential therapeutic targets for treatment of HD and SCAs.
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Affiliation(s)
- Ilya Bezprozvanny
- Department of Physiology, ND12.200AA, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390-9040, USA.
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50
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Yu Z, Bonini NM. Modeling human trinucleotide repeat diseases in Drosophila. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2011; 99:191-212. [PMID: 21906541 DOI: 10.1016/b978-0-12-387003-2.00008-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Drosophila is a powerful model system to study human trinucleotide repeat diseases. Findings in Drosophila models highlighted importance of host proteins, chaperons, and protein clearance pathways in polyglutamine diseases as well as that of RNA-binding proteins in noncoding repeat RNA toxicity diseases. Recent novel aspects revealed in Drosophila models include pleiotropic Ataxin 2 interactions, antisense transcription in trinucleotide repeat diseases, contribution of CAG RNA in polyglutamine diseases, and the role of RNA foci in CUG expansion diseases. Drosophila models have been also used for repeat stability studies.
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Affiliation(s)
- Zhenming Yu
- Department of Biology, 415 S University Ave., University of Pennsylvania, PA, USA
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