1
|
Petrauskas A, Fortunati DL, Kandi AR, Pothapragada SS, Agrawal K, Singh A, Huelsmeier J, Hillebrand J, Brown G, Chaturvedi D, Lee J, Lim C, Auburger G, VijayRaghavan K, Ramaswami M, Bakthavachalu B. Structured and disordered regions of Ataxin-2 contribute differently to the specificity and efficiency of mRNP granule formation. PLoS Genet 2024; 20:e1011251. [PMID: 38768217 DOI: 10.1371/journal.pgen.1011251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 06/11/2024] [Accepted: 04/05/2024] [Indexed: 05/22/2024] Open
Abstract
Ataxin-2 (ATXN2) is a gene implicated in spinocerebellar ataxia type II (SCA2), amyotrophic lateral sclerosis (ALS) and Parkinsonism. The encoded protein is a therapeutic target for ALS and related conditions. ATXN2 (or Atx2 in insects) can function in translational activation, translational repression, mRNA stability and in the assembly of mRNP-granules, a process mediated by intrinsically disordered regions (IDRs). Previous work has shown that the LSm (Like-Sm) domain of Atx2, which can help stimulate mRNA translation, antagonizes mRNP-granule assembly. Here we advance these findings through a series of experiments on Drosophila and human Ataxin-2 proteins. Results of Targets of RNA Binding Proteins Identified by Editing (TRIBE), co-localization and immunoprecipitation experiments indicate that a polyA-binding protein (PABP) interacting, PAM2 motif of Ataxin-2 may be a major determinant of the mRNA and protein content of Ataxin-2 mRNP granules. Experiments with transgenic Drosophila indicate that while the Atx2-LSm domain may protect against neurodegeneration, structured PAM2- and unstructured IDR- interactions both support Atx2-induced cytotoxicity. Taken together, the data lead to a proposal for how Ataxin-2 interactions are remodelled during translational control and how structured and non-structured interactions contribute differently to the specificity and efficiency of RNP granule condensation as well as to neurodegeneration.
Collapse
Affiliation(s)
- 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, Ireland
| | - Daniel L Fortunati
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Arvind Reddy Kandi
- School of Biosciences and Bioengineering, Indian Institute of Technology, Mandi, India
| | | | - Khushboo Agrawal
- Tata Institute for Genetics and Society Centre at inStem, Bellary Road, Bangalore, India
- School of Biotechnology, Amrita Vishwa Vidyapeetham University, Kollam, Kerala, India
| | - Amanjot Singh
- National Centre for Biological Sciences, TIFR, Bangalore, India
- Manipal Institute of Regenerative Medicine, MAHE-Bengaluru, Govindapura, Bengaluru, India
| | - 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, 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, Ireland
| | - Georgia Brown
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | | | - Jongbo Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, Republic of Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology (UNIST), 50 UNIST-gil, Ulsan, Republic of Korea
| | - Georg Auburger
- Experimental Neurology, Medical School, Goethe University, Frankfurt, Germany
| | - K VijayRaghavan
- National Centre for Biological Sciences, TIFR, Bangalore, India
| | - Mani Ramaswami
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
- National Centre for Biological Sciences, TIFR, Bangalore, India
| | - Baskar Bakthavachalu
- School of Biosciences and Bioengineering, Indian Institute of Technology, Mandi, India
- Tata Institute for Genetics and Society Centre at inStem, Bellary Road, Bangalore, India
| |
Collapse
|
2
|
Chitre M, Emery P. ATXN2 is a target of N-terminal proteolysis. PLoS One 2023; 18:e0296085. [PMID: 38128014 PMCID: PMC10735043 DOI: 10.1371/journal.pone.0296085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023] Open
Abstract
Spinocerebellar ataxia 2 (SCA2) is a neurodegenerative disorder caused by the expansion of the poly-glutamine (polyQ) tract of Ataxin-2 (ATXN2). Other polyQ-containing proteins such as ATXN7 and huntingtin are associated with the development of neurodegenerative diseases when their N-terminal polyQ domains are expanded. Furthermore, they undergo proteolytic processing events that produce N-terminal fragments that include the polyQ stretch, which are implicated in pathogenesis. Interestingly, N-terminal ATXN2 fragments were reported in a brain extract from a SCA2 patient, but it is currently unknown whether an expanded polyQ domain contributes to ATXN2 proteolytic susceptibility. Here, we used transient expression in HEK293 cells to determine whether ATXN2 is a target for specific N-terminal proteolysis. We found that ATXN2 proteins with either normal or expanded polyQ stretches undergo proteolytic cleavage releasing an N-terminal polyQ-containing fragment. We identified a short amino acid sequence downstream of the polyQ domain that is necessary for N-terminal cleavage of full-length ATXN2 and sufficient to induce proteolysis of a heterologous protein. However, this sequence is not required for cleavage of a short ATXN2 isoform produced from an alternative start codon located just upstream of the CAG repeats encoding the polyQ domain. Our study extends our understanding of ATXN2 posttranslational regulation by revealing that this protein can be the target of specific proteolytic cleavage events releasing polyQ-containing products that are modulated by the N-terminal domain of ATXN2. N-terminal ATXN2 proteolysis of expanded polyQ domains might contribute to SCA2 pathology, as observed in other neurodegenerative disorders caused by polyQ domain expansion.
Collapse
Affiliation(s)
- Monika Chitre
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| | - Patrick Emery
- Department of Neurobiology, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, Morningside Graduate School of Biomedical Sciences, University of Massachusetts Chan Medical School, Worcester, Massachusetts, United States of America
| |
Collapse
|
3
|
Ripin N, Parker R. Formation, function, and pathology of RNP granules. Cell 2023; 186:4737-4756. [PMID: 37890457 PMCID: PMC10617657 DOI: 10.1016/j.cell.2023.09.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 07/28/2023] [Accepted: 09/07/2023] [Indexed: 10/29/2023]
Abstract
Ribonucleoprotein (RNP) granules are diverse membrane-less organelles that form through multivalent RNA-RNA, RNA-protein, and protein-protein interactions between RNPs. RNP granules are implicated in many aspects of RNA physiology, but in most cases their functions are poorly understood. RNP granules can be described through four key principles. First, RNP granules often arise because of the large size, high localized concentrations, and multivalent interactions of RNPs. Second, cells regulate RNP granule formation by multiple mechanisms including posttranslational modifications, protein chaperones, and RNA chaperones. Third, RNP granules impact cell physiology in multiple manners. Finally, dysregulation of RNP granules contributes to human diseases. Outstanding issues in the field remain, including determining the scale and molecular mechanisms of RNP granule function and how granule dysfunction contributes to human disease.
Collapse
Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80303, USA.
| |
Collapse
|
4
|
Park S, Dahn R, Kurt E, Presle A, VanDenHeuvel K, Moravec C, Jambhekar A, Olukoga O, Shepherd J, Echard A, Blower M, Skop AR. The mammalian midbody and midbody remnant are assembly sites for RNA and localized translation. Dev Cell 2023; 58:1917-1932.e6. [PMID: 37552987 PMCID: PMC10592306 DOI: 10.1016/j.devcel.2023.07.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 06/20/2023] [Accepted: 07/17/2023] [Indexed: 08/10/2023]
Abstract
Long ignored as a vestigial remnant of cytokinesis, the mammalian midbody (MB) is released post-abscission inside large extracellular vesicles called MB remnants (MBRs). Recent evidence suggests that MBRs can modulate cell proliferation and cell fate decisions. Here, we demonstrate that the MB matrix is the site of ribonucleoprotein assembly and is enriched in mRNAs that encode proteins involved in cell fate, oncogenesis, and pluripotency, which we are calling the MB granule. Both MBs and post-abscission MBRs are sites of spatiotemporally regulated translation, which is initiated when nascent daughter cells re-enter G1 and continues after extracellular release. MKLP1 and ARC are necessary for the localization and translation of RNA in the MB dark zone, whereas ESCRT-III is necessary to maintain translation levels in the MB. Our work reveals a unique translation event that occurs during abscission and within a large extracellular vesicle.
Collapse
Affiliation(s)
- Sungjin Park
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Randall Dahn
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Elif Kurt
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Adrien Presle
- Institut Pasteur, Université de Paris, CNRS UMR3691, Membrane Traffic and Cell Division Unit, 25-28 rue du Dr Roux, 75015 Paris, France; Sorbonne Université, Collège doctoral, 75005 Paris, France
| | - Kathryn VanDenHeuvel
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Cara Moravec
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Olushola Olukoga
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA
| | - Jason Shepherd
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Arnaud Echard
- Institut Pasteur, Université de Paris, CNRS UMR3691, Membrane Traffic and Cell Division Unit, 25-28 rue du Dr Roux, 75015 Paris, France
| | - Michael Blower
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - Ahna R Skop
- Laboratory of Genetics and Medical Genetics, University of Wisconsin-Madison, Madison, WI, USA.
| |
Collapse
|
5
|
Boeynaems S, Dorone Y, Zhuang Y, Shabardina V, Huang G, Marian A, Kim G, Sanyal A, Şen NE, Griffith D, Docampo R, Lasker K, Ruiz-Trillo I, Auburger G, Holehouse AS, Kabashi E, Lin Y, Gitler AD. Poly(A)-binding protein is an ataxin-2 chaperone that regulates biomolecular condensates. Mol Cell 2023; 83:2020-2034.e6. [PMID: 37295429 PMCID: PMC10318123 DOI: 10.1016/j.molcel.2023.05.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 03/14/2023] [Accepted: 05/17/2023] [Indexed: 06/12/2023]
Abstract
Biomolecular condensation underlies the biogenesis of an expanding array of membraneless assemblies, including stress granules (SGs), which form under a variety of cellular stresses. Advances have been made in understanding the molecular grammar of a few scaffold proteins that make up these phases, but how the partitioning of hundreds of SG proteins is regulated remains largely unresolved. While investigating the rules that govern the condensation of ataxin-2, an SG protein implicated in neurodegenerative disease, we unexpectedly identified a short 14 aa sequence that acts as a condensation switch and is conserved across the eukaryote lineage. We identify poly(A)-binding proteins as unconventional RNA-dependent chaperones that control this regulatory switch. Our results uncover a hierarchy of cis and trans interactions that fine-tune ataxin-2 condensation and reveal an unexpected molecular function for ancient poly(A)-binding proteins as regulators of biomolecular condensate proteins. These findings may inspire approaches to therapeutically target aberrant phases in disease.
Collapse
Affiliation(s)
- Steven Boeynaems
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA; Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX 77030, USA; Therapeutic Innovation Center (THINC), Baylor College of Medicine, Houston, TX 77030, USA; Center for Alzheimer's and Neurodegenerative Diseases (CAND), Texas Children's Hospital, Houston, TX 77030, USA; Dan L Duncan Comprehensive Cancer Center (DLDCCC), Baylor College of Medicine, Houston, TX 77030, USA; Department of Genetics, Stanford University, Stanford, CA 94305, USA.
| | - Yanniv Dorone
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Yanrong Zhuang
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Centre for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Victoria Shabardina
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003 Catalonia, Spain
| | - Guozhong Huang
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Anca Marian
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France
| | - Garam Kim
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Anushka Sanyal
- Department of Genetics, Stanford University, Stanford, CA 94305, USA
| | - Nesli-Ece Şen
- Experimental Neurology, Goethe-University Hospital, 60590 Frankfurt, Germany
| | - Daniel Griffith
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Biomolecular Condensates, Washington University in St Louis, St. Louis, MO 63130, USA
| | - Roberto Docampo
- Department of Cellular Biology and Center for Tropical and Emerging Global Diseases, University of Georgia, Athens, GA 30602, USA
| | - Keren Lasker
- The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Iñaki Ruiz-Trillo
- Institut de Biologia Evolutiva (CSIC-Universitat Pompeu Fabra), Passeig Marítim de la Barceloneta 37-49, Barcelona 08003 Catalonia, Spain; ICREA, Passeig Lluís Companys 23, Barcelona 08010 Catalonia, Spain
| | - Georg Auburger
- Experimental Neurology, Goethe-University Hospital, 60590 Frankfurt, Germany
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Biomolecular Condensates, Washington University in St Louis, St. Louis, MO 63130, USA
| | - Edor Kabashi
- Imagine Institute, Institut National de la Santé et de la Recherche Médicale (INSERM) Unité 1163, Paris Descartes Université, 75015 Paris, France
| | - Yi Lin
- IDG/McGovern Institute for Brain Research, Tsinghua-Peking Joint Centre for Life Sciences, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Aaron D Gitler
- Department of Genetics, Stanford University, Stanford, CA 94305, USA; Chan Zuckerberg Biohub, San Francisco, CA 94158, USA.
| |
Collapse
|
6
|
van de Poll F, Sutter BM, Acoba MG, Caballero D, Jahangiri S, Yang YS, Lee CD, Tu BP. Pbp1 associates with Puf3 and promotes translation of its target mRNAs involved in mitochondrial biogenesis. PLoS Genet 2023; 19:e1010774. [PMID: 37216416 PMCID: PMC10237644 DOI: 10.1371/journal.pgen.1010774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/02/2023] [Accepted: 05/07/2023] [Indexed: 05/24/2023] Open
Abstract
Pbp1 (poly(A)-binding protein-binding protein 1) is a cytoplasmic stress granule marker that is capable of forming condensates that function in the negative regulation of TORC1 signaling under respiratory conditions. Polyglutamine expansions in its mammalian ortholog ataxin-2 lead to spinocerebellar dysfunction due to toxic protein aggregation. Here, we show that loss of Pbp1 in S. cerevisiae leads to decreased amounts of mRNAs and mitochondrial proteins which are targets of Puf3, a member of the PUF (Pumilio and FBF) family of RNA-binding proteins. We found that Pbp1 supports the translation of Puf3-target mRNAs in respiratory conditions, such as those involved in the assembly of cytochrome c oxidase and subunits of mitochondrial ribosomes. We further show that Pbp1 and Puf3 interact through their respective low complexity domains, which is required for Puf3-target mRNA translation. Our findings reveal a key role for Pbp1-containing assemblies in enabling the translation of mRNAs critical for mitochondrial biogenesis and respiration. They may further explain prior associations of Pbp1/ataxin-2 with RNA, stress granule biology, mitochondrial function, and neuronal health.
Collapse
Affiliation(s)
- Floortje van de Poll
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Benjamin M. Sutter
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michelle Grace Acoba
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Daniel Caballero
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Samira Jahangiri
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Yu-San Yang
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Chien-Der Lee
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Benjamin P. Tu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| |
Collapse
|
7
|
Gulino R. Synaptic Dysfunction and Plasticity in Amyotrophic Lateral Sclerosis. Int J Mol Sci 2023; 24:ijms24054613. [PMID: 36902042 PMCID: PMC10003601 DOI: 10.3390/ijms24054613] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/23/2023] [Accepted: 02/24/2023] [Indexed: 03/03/2023] Open
Abstract
Recent evidence has supported the hypothesis that amyotrophic lateral sclerosis (ALS) is a multi-step disease, as the onset of symptoms occurs after sequential exposure to a defined number of risk factors. Despite the lack of precise identification of these disease determinants, it is known that genetic mutations may contribute to one or more of the steps leading to ALS onset, the remaining being linked to environmental factors and lifestyle. It also appears evident that compensatory plastic changes taking place at all levels of the nervous system during ALS etiopathogenesis may likely counteract the functional effects of neurodegeneration and affect the timing of disease onset and progression. Functional and structural events of synaptic plasticity probably represent the main mechanisms underlying this adaptive capability, causing a significant, although partial and transient, resiliency of the nervous system affected by a neurodegenerative disease. On the other hand, the failure of synaptic functions and plasticity may be part of the pathological process. The aim of this review was to summarize what it is known today about the controversial involvement of synapses in ALS etiopathogenesis, and an analysis of the literature, although not exhaustive, confirmed that synaptic dysfunction is an early pathogenetic process in ALS. Moreover, it appears that adequate modulation of structural and functional synaptic plasticity may likely support function sparing and delay disease progression.
Collapse
Affiliation(s)
- Rosario Gulino
- Department of Biomedical and Biotechnological Sciences, Physiology Section, University of Catania, 95123 Catania, Italy
| |
Collapse
|
8
|
Wijegunawardana D, Vishal SS, Venkatesh N, Gopal PP. Ataxin-2 polyglutamine expansions aberrantly sequester TDP-43, drive ribonucleoprotein condensate transport dysfunction and suppress local translation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.30.526372. [PMID: 36778347 PMCID: PMC9915502 DOI: 10.1101/2023.01.30.526372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Altered RNA metabolism is a common pathogenic mechanism linked to familial and sporadic Amyotrophic lateral sclerosis (ALS). ALS is characterized by mislocalization and aggregation of TDP-43, an RNA-binding protein (RBP) with multiple roles in post-transcriptional RNA processing. Recent studies have identified genetic interactions between TDP-43 and Ataxin-2, a polyglutamine (polyQ) RBP in which intermediate length polyQ expansions confer increased ALS risk. Here, we used live-cell confocal imaging, photobleaching and translation reporter assays to study the localization, transport dynamics and mRNA regulatory functions of TDP-43/Ataxin-2 in rodent primary cortical neurons. We show that Ataxin-2 polyQ expansions aberrantly sequester TDP-43 within ribonucleoprotein (RNP) condensates, and disrupt both its motility along the axon and liquid-like properties. Our data suggest that Ataxin-2 governs motility and translation of neuronal RNP condensates and that Ataxin-2 polyQ expansions fundamentally perturb spatial localization of mRNA and suppress local translation. Overall, these results indicate Ataxin-2 polyQ expansions have detrimental effects on stability, localization, and translation of transcripts critical for axonal and cytoskeletal integrity, particularly important for motor neurons.
Collapse
|
9
|
Palozzi JM, Jeedigunta SP, Minenkova AV, Monteiro VL, Thompson ZS, Lieber T, Hurd TR. Mitochondrial DNA quality control in the female germline requires a unique programmed mitophagy. Cell Metab 2022; 34:1809-1823.e6. [PMID: 36323236 DOI: 10.1016/j.cmet.2022.10.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 08/22/2022] [Accepted: 10/06/2022] [Indexed: 11/07/2022]
Abstract
Mitochondria have their own DNA (mtDNA), which is susceptible to the accumulation of disease-causing mutations. To prevent deleterious mutations from being inherited, the female germline has evolved a conserved quality control mechanism that remains poorly understood. Here, through a large-scale screen, we uncover a unique programmed germline mitophagy (PGM) that is essential for mtDNA quality control. We find that PGM is developmentally triggered as germ cells enter meiosis by inhibition of the target of rapamycin complex 1 (TORC1). We identify a role for the RNA-binding protein Ataxin-2 (Atx2) in coordinating the timing of PGM with meiosis. We show that PGM requires the mitophagy receptor BNIP3, mitochondrial fission and translation factors, and members of the Atg1 complex, but not the mitophagy factors PINK1 and Parkin. Additionally, we report several factors that are critical for germline mtDNA quality control and show that pharmacological manipulation of one of these factors promotes mtDNA quality control.
Collapse
Affiliation(s)
- Jonathan M Palozzi
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Swathi P Jeedigunta
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Anastasia V Minenkova
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Vernon L Monteiro
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Zoe S Thompson
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada
| | - Toby Lieber
- HHMI and Kimmel Center for Biology and Medicine of the Skirball Institute, Department of Cell Biology, New York University School of Medicine, New York, NY, USA
| | - Thomas R Hurd
- Department of Molecular Genetics, University of Toronto, 661 University Avenue, Toronto, ON M5G 1M1, Canada.
| |
Collapse
|
10
|
Rodriguez CM, Bechek SC, Jones GL, Nakayama L, Akiyama T, Kim G, Solow-Cordero DE, Strittmatter SM, Gitler AD. Targeting RTN4/NoGo-Receptor reduces levels of ALS protein ataxin-2. Cell Rep 2022; 41:111505. [PMID: 36288715 PMCID: PMC9664481 DOI: 10.1016/j.celrep.2022.111505] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 05/30/2022] [Accepted: 09/22/2022] [Indexed: 01/27/2023] Open
Abstract
Gene-based therapeutic strategies to lower ataxin-2 levels are emerging for the neurodegenerative diseases amyotrophic lateral sclerosis (ALS) and spinocerebellar ataxia type 2 (SCA2). Additional strategies to lower levels of ataxin-2 could be beneficial. Here, we perform a genome-wide arrayed small interfering RNA (siRNA) screen in human cells and identify RTN4R, the gene encoding the RTN4/NoGo-Receptor, as a potent modifier of ataxin-2 levels. RTN4R knockdown, or treatment with a peptide inhibitor, is sufficient to lower ataxin-2 protein levels in mouse and human neurons in vitro, and Rtn4r knockout mice have reduced ataxin-2 levels in vivo. We provide evidence that ataxin-2 shares a role with the RTN4/NoGo-Receptor in limiting axonal regeneration. Reduction of either protein increases axonal regrowth following axotomy. These data define the RTN4/NoGo-Receptor as a novel therapeutic target for ALS and SCA2 and implicate the targeting of ataxin-2 as a potential treatment following nerve injury.
Collapse
Affiliation(s)
- Caitlin M Rodriguez
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Sophia C Bechek
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Graham L Jones
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, USA
| | - Lisa Nakayama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Tetsuya Akiyama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Garam Kim
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA; Stanford Neurosciences Interdepartmental Program, Stanford University School of Medicine, Stanford, CA, USA
| | - David E Solow-Cordero
- High-Throughput Bioscience Center, Department of Chemical and Systems Biology, Stanford University, Stanford, CA, USA
| | - Stephen M Strittmatter
- Program in Cellular Neuroscience, Neurodegeneration and Repair, Yale University School of Medicine, New Haven, CT, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
| |
Collapse
|
11
|
Lasker K, Boeynaems S, Lam V, Scholl D, Stainton E, Briner A, Jacquemyn M, Daelemans D, Deniz A, Villa E, Holehouse AS, Gitler AD, Shapiro L. The material properties of a bacterial-derived biomolecular condensate tune biological function in natural and synthetic systems. Nat Commun 2022; 13:5643. [PMID: 36163138 PMCID: PMC9512792 DOI: 10.1038/s41467-022-33221-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 09/09/2022] [Indexed: 11/17/2022] Open
Abstract
Intracellular phase separation is emerging as a universal principle for organizing biochemical reactions in time and space. It remains incompletely resolved how biological function is encoded in these assemblies and whether this depends on their material state. The conserved intrinsically disordered protein PopZ forms condensates at the poles of the bacterium Caulobacter crescentus, which in turn orchestrate cell-cycle regulating signaling cascades. Here we show that the material properties of these condensates are determined by a balance between attractive and repulsive forces mediated by a helical oligomerization domain and an expanded disordered region, respectively. A series of PopZ mutants disrupting this balance results in condensates that span the material properties spectrum, from liquid to solid. A narrow range of condensate material properties supports proper cell division, linking emergent properties to organismal fitness. We use these insights to repurpose PopZ as a modular platform for generating tunable synthetic condensates in human cells. “Intracellular phase separation is emerging as a universal principle for organizing biochemical reactions in time and space. Here the authors show that PopZ condensate dynamics support cell division and using PopZ modular architecture, the tunable PopTag platform was developed to enable designer condensates.”
Collapse
Affiliation(s)
- Keren Lasker
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA. .,Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA.
| | - Steven Boeynaems
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA
| | - Vinson Lam
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA, USA
| | - Daniel Scholl
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Emma Stainton
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Adam Briner
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, Brisbane, QLD, Australia
| | - Maarten Jacquemyn
- KU Leuven Department of Microbiology, Immunology, and Transplantation, Laboratory of Virology and Chemotherapy, Rega Institute, KU Leuven, Leuven, Belgium
| | - Dirk Daelemans
- KU Leuven Department of Microbiology, Immunology, and Transplantation, Laboratory of Virology and Chemotherapy, Rega Institute, KU Leuven, Leuven, Belgium
| | - Ashok Deniz
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Elizabeth Villa
- Department of Molecular Biology, School of Biological Sciences, University of California San Diego, La Jolla, CA, USA.,Howard Hughes Medical Institute, University of California San Diego, La Jolla, CA, USA
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University in St. Louis, St. Louis, MO, USA.,Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA, USA.
| | - Lucy Shapiro
- Department of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA.
| |
Collapse
|
12
|
Blok LER, Boon M, van Reijmersdal B, Höffler KD, Fenckova M, Schenck A. Genetics, molecular control and clinical relevance of habituation learning. Neurosci Biobehav Rev 2022; 143:104883. [PMID: 36152842 DOI: 10.1016/j.neubiorev.2022.104883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/08/2022] [Accepted: 08/30/2022] [Indexed: 11/29/2022]
Abstract
Habituation is the most fundamental form of learning. As a firewall that protects our brain from sensory overload, it is indispensable for cognitive processes. Studies in humans and animal models provide increasing evidence that habituation is affected in autism and related monogenic neurodevelopmental disorders (NDDs). An integrated application of habituation assessment in NDDs and their animal models has unexploited potential for neuroscience and medical care. With the aim to gain mechanistic insights, we systematically retrieved genes that have been demonstrated in the literature to underlie habituation. We identified 258 evolutionarily conserved genes across species, describe the biological processes they converge on, and highlight regulatory pathways and drugs that may alleviate habituation deficits. We also summarize current habituation paradigms and extract the most decisive arguments that support the crucial role of habituation for cognition in health and disease. We conclude that habituation is a conserved, quantitative, cognition- and disease-relevant process that can connect preclinical and clinical work, and hence is a powerful tool to advance research, diagnostics, and treatment of NDDs.
Collapse
Affiliation(s)
- Laura Elisabeth Rosalie Blok
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Marina Boon
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Boyd van Reijmersdal
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Kira Daniela Höffler
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| | - Michaela Fenckova
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands; Department of Molecular Biology and Genetics, Faculty of Science, University of South Bohemia in Ceske Budejovice, Branisovska 31, 37005, Ceske Budejovice, Czech Republic.
| | - Annette Schenck
- Department of Human Genetics, Donders Institute for Brain, Cognition and Behaviour, Radboud University Medical Center, Geert Grooteplein Zuid 10, 6525GA, Nijmegen, the Netherlands.
| |
Collapse
|
13
|
Li Z, Liu X, Liu M. Stress Granule Homeostasis, Aberrant Phase Transition, and Amyotrophic Lateral Sclerosis. ACS Chem Neurosci 2022; 13:2356-2370. [PMID: 35905138 DOI: 10.1021/acschemneuro.2c00262] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. In recent years, a large number of ALS-related mutations have been discovered to have a strong link to stress granules (SGs). SGs are cytoplasmic ribonucleoprotein condensates mediated by liquid-liquid phase separation (LLPS) of biomacromolecules. They help cells cope with stress. The normal physiological functions of SGs are dependent on three key aspects of SG "homeostasis": SG assembly, disassembly, and SG components. Any of these three aspects can be disrupted, resulting in abnormalities in the cellular stress response and leading to cytotoxicity. Several ALS-related pathogenic mutants have abnormal LLPS abilities that disrupt SG homeostasis, and some of them can even cause aberrant phase transitions. As a result, ALS-related mutants may disrupt various aspects of SG homeostasis by directly disturbing the intermolecular interactions or affecting core SG components, thus disrupting the phase equilibrium of the cytoplasm during stress. Considering that the importance of the "global view" of SG homeostasis in ALS pathogenesis has not received enough attention, we first systematically summarize the physiological regulatory mechanism of SG homeostasis based on LLPS and then examine ALS pathogenesis from the perspective of disrupted SG homeostasis and aberrant phase transition of biomacromolecules.
Collapse
Affiliation(s)
- Zhanxu Li
- Xiangya School of Medicine, Central South University, Changsha 410078, Hunan, China
| | - Xionghao Liu
- Center for Medical Genetics & Hunan Key Laboratory of Medical Genetics, School of Life Sciences, Central South University, Changsha 410008, Hunan, China
| | - Mujun Liu
- Department of Cell Biology, School of Life Sciences, Central South University, Changsha 410078, Hunan, China
| |
Collapse
|
14
|
Baud A, Derbis M, Tutak K, Sobczak K. Partners in crime: Proteins implicated in
RNA
repeat expansion diseases. WIRES RNA 2022; 13:e1709. [PMID: 35229468 PMCID: PMC9539487 DOI: 10.1002/wrna.1709] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 12/07/2021] [Accepted: 12/08/2021] [Indexed: 11/06/2022]
Affiliation(s)
- Anna Baud
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Magdalena Derbis
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Katarzyna Tutak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| | - Krzysztof Sobczak
- Department of Gene Expression Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University Poznan Poland
| |
Collapse
|
15
|
Baranova A, Cao H, Chen J, Zhang F. Causal Association and Shared Genetics Between Asthma and COVID-19. Front Immunol 2022; 13:705379. [PMID: 35386719 PMCID: PMC8977836 DOI: 10.3389/fimmu.2022.705379] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 02/25/2022] [Indexed: 12/14/2022] Open
Abstract
Objectives Recent studies suggest that asthma may have a protective effect on COVID-19.We aimed to investigate the causality between asthma and two COVID-19 outcomes and explore the mechanisms underlining this connection. Methods Summary results of GWAS were used for the analyses, including asthma (88,486 cases and 447,859 controls), COVID-19 hospitalization (6,406 hospitalized COVID-19 cases and 902,088 controls), and COVID-19 infection (14,134 COVID-19 cases and 1,284,876 controls). The Mendelian randomization (MR) analysis was performed to evaluate the causal effects of asthma on the two COVID-19 outcomes. A cross-trait meta-analysis was conducted to analyze genetic variants within two loci shared by COVID-19 hospitalization and asthma. Results Asthma is associated with decreased risk both for COVID-19 hospitalization (odds ratio (OR): 0.70, 95% confidence interval (CI): 0.70-0.99) and for COVID-19 infection (OR: 0.83, 95%CI: 0.51-0.95). Asthma and COVID-19 share two genome-wide significant genes, including ABO at the 9q34.2 region and OAS2 at the 12q24.13 region. The meta-analysis revealed that ABO and ATXN2 contain variants with pleiotropic effects on both COVID-19 and asthma. Conclusion In conclusion, our results suggest that genetic liability to asthma is associated with decreased susceptibility to SARS-CoV-2 and to severe COVID-19 disease, which may be due to the protective effects of ongoing inflammation and, possibly, related compensatory responses against COVID-19 in its early stage.
Collapse
Affiliation(s)
- Ancha Baranova
- School of Systems Biology, George Mason University, Fairfax, VA, United States.,Research Centre for Medical Genetics, Moscow, Russia
| | - Hongbao Cao
- School of Systems Biology, George Mason University, Fairfax, VA, United States
| | - Jiu Chen
- Institute of Neuropsychiatry, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China
| | - Fuquan Zhang
- Institute of Neuropsychiatry, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China.,Department of Psychiatry, The Affiliated Brain Hospital of Nanjing Medical University, Nanjing, China
| |
Collapse
|
16
|
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.
Collapse
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
| |
Collapse
|
17
|
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
Collapse
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
| |
Collapse
|
18
|
Singh A, Kandi AR, Jayaprakashappa D, Thuery G, Purohit DJ, Huelsmeier J, Singh R, Pothapragada SS, Ramaswami M, Bakthavachalu B. The Transcriptional Response to Oxidative Stress is Independent of Stress-Granule Formation. Mol Biol Cell 2022; 33:ar25. [PMID: 34985933 PMCID: PMC9250384 DOI: 10.1091/mbc.e21-08-0418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Cells respond to stress with translational arrest, robust transcriptional changes, and transcription-independent formation of mRNP assemblies termed stress granules (SGs). Despite considerable interest in the role of SGs in oxidative, unfolded-protein and viral stress responses, whether and how SGs contribute to stress-induced transcription has not been rigorously examined. To address this, we characterized transcriptional changes in Drosophila S2 cells induced by acute oxidative-stress and assessed how these were altered under conditions that disrupted SG assembly. Oxidative stress for 3-hours predominantly resulted in induction or upregulation of stress-responsive mRNAs whose levels peaked during recovery after stress cessation. The stress-transcriptome is enriched in mRNAs coding for chaperones, including HSP70s, small heat shock proteins, glutathione transferases, and several non-coding RNAs. Oxidative stress also induced cytoplasmic SGs that disassembled 3-hours after stress cessation. As expected, RNAi-mediated knockdown of the conserved G3BP1/Rasputin protein inhibited SG assembly. However, this disruption had no significant effect on the stress-induced transcriptional response or stress-induced translational arrest. Thus, SG assembly and stress-induced gene expression alterations appear to be driven by distinctive signaling processes. We suggest that while SG assembly represents a fast, transient mechanism, the transcriptional response enables a slower, longer-lasting mechanism for adaptation to and recovery from cell stress.
Collapse
Affiliation(s)
- Amanjot Singh
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| | - Arvind Reddy Kandi
- Tata Institute for Genetics and Society Centre at inStem, Bellary Road, Bangalore 560065, India
| | | | - Guillaume Thuery
- 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
| | - Devam J Purohit
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| | - 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
| | - Rashi Singh
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| | | | - 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
| | - Baskar Bakthavachalu
- Tata Institute for Genetics and Society Centre at inStem, Bellary Road, Bangalore 560065, India.,School of Basic Sciences, Indian Institute of Technology, Mandi 175005, India
| |
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
Ripin N, Parker R. Are stress granules the RNA analogs of misfolded protein aggregates? RNA (NEW YORK, N.Y.) 2022; 28:67-75. [PMID: 34670846 PMCID: PMC8675284 DOI: 10.1261/rna.079000.121] [Citation(s) in RCA: 28] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Ribonucleoprotein granules are ubiquitous features of eukaryotic cells. Several observations argue that the formation of at least some RNP granules can be considered analogous to the formation of unfolded protein aggregates. First, unfolded protein aggregates form from the exposure of promiscuous protein interaction surfaces, while some mRNP granules form, at least in part, by promiscuous intermolecular RNA-RNA interactions due to exposed RNA surfaces when mRNAs are not engaged with ribosomes. Second, analogous to the role of protein chaperones in preventing misfolded protein aggregation, cells contain abundant "RNA chaperones" to limit inappropriate RNA-RNA interactions and prevent mRNP granule formation. Third, analogous to the role of protein aggregates in diseases, situations where RNA aggregation exceeds the capacity of RNA chaperones to disaggregate RNAs may contribute to human disease. Understanding that RNP granules can be considered as promiscuous, reversible RNA aggregation events allow insight into their composition and how cells have evolved functions for RNP granules.
Collapse
Affiliation(s)
- Nina Ripin
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| | - Roy Parker
- Department of Biochemistry and Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, Colorado 80303, USA
| |
Collapse
|
21
|
De Graeve F, Formicola N, Pushpalatha KV, Nakamura A, Debreuve E, Descombes X, Besse F. Detecting Stress Granules in Drosophila Neurons. Methods Mol Biol 2022; 2428:229-242. [PMID: 35171483 DOI: 10.1007/978-1-0716-1975-9_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Stress granules (SGs) are cytoplasmic ribonucleoprotein condensates that dynamically and reversibly assemble in response to stress. They are thought to contribute to the adaptive stress response by storing translationally inactive mRNAs as well as signaling molecules. Recent work has shown that SG composition and properties depend on both stress and cell types, and that neurons exhibit a complex SG proteome and a strong vulnerability to mutations in SG proteins. Drosophila has emerged as a powerful genetically tractable organism where to study the physiological regulation and functions of SGs in normal and pathological contexts. In this chapter, we describe a protocol enabling quantitative analysis of SG properties in both larval and adult Drosophila CNS samples. In this protocol, fluorescently tagged SGs are induced upon acute ex vivo stress or chronic in vivo stress, imaged at high-resolution via confocal microscopy and detected automatically, using a dedicated software.
Collapse
Affiliation(s)
- Fabienne De Graeve
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | - Nadia Formicola
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | | | - Akira Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, and Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Eric Debreuve
- Université Côte d'Azur, CNRS, Inria, Laboratoire I3S, Sophia Antipolis, France
| | - Xavier Descombes
- Université Côte d'Azur, Inria, CNRS, Laboratoire I3S, Sophia Antipolis, France
| | - Florence Besse
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France.
| |
Collapse
|
22
|
Huelsmeier J, Walker E, Bakthavachalu B, Ramaswami M. A C-terminal ataxin-2 disordered region promotes Huntingtin protein aggregation and neurodegeneration in Drosophila models of Huntington’s disease. G3 GENES|GENOMES|GENETICS 2021; 11:6385240. [PMID: 34718534 PMCID: PMC8664476 DOI: 10.1093/g3journal/jkab355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Accepted: 10/01/2021] [Indexed: 11/15/2022]
Abstract
The Ataxin-2 (Atx2) protein contributes to the progression of neurodegenerative phenotypes in animal models of amyotrophic lateral sclerosis (ALS), type 2 spinocerebellar ataxia (SCA-2), Parkinson’s disease, and Huntington’s disease (HD). However, because the Atx2 protein contains multiple separable activities, deeper understanding requires experiments to address the exact mechanisms by which Atx2 modulates neurodegeneration (ND) progression. Recent work on two ALS models, C9ORF72 and FUS, in Drosophila has shown that a C-terminal intrinsically disordered region (cIDR) of Atx2 protein, required for assembly of ribonucleoprotein (RNP) granules, is essential for the progression of neurodegenerative phenotypes as well as for accumulation of protein inclusions associated with these ALS models. Here, we show that the Atx2-cIDR also similarly contributes to the progression of degenerative phenotypes and accumulation of Huntingtin protein aggregates in Drosophila models of HD. Because Huntingtin is not an established component of RNP granules, these observations support a recently hypothesized, unexpected protein-handling function for RNP granules, which could contribute to the progression of Huntington’s disease and, potentially, other proteinopathies.
Collapse
Affiliation(s)
- Joern Huelsmeier
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Emily Walker
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
| | - Baskar Bakthavachalu
- School of Basic Science, Indian Institute of Technology, Mandi, Suran 175075, India
| | - Mani Ramaswami
- School of Genetics and Microbiology, Trinity College Institute of Neuroscience, Trinity College Dublin, Dublin 2, Ireland
- National Centre for Biological Sciences, TIFR, Bangalore 560065, India
| |
Collapse
|
23
|
Sharpe JL, Harper NS, Garner DR, West RJH. Modeling C9orf72-Related Frontotemporal Dementia and Amyotrophic Lateral Sclerosis in Drosophila. Front Cell Neurosci 2021; 15:770937. [PMID: 34744635 PMCID: PMC8566814 DOI: 10.3389/fncel.2021.770937] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2021] [Accepted: 09/27/2021] [Indexed: 12/28/2022] Open
Abstract
An intronic hexanucleotide (GGGGCC) expansion in the C9orf72 gene is the most common genetic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). In the decade following its discovery, much progress has been made in enhancing our understanding of how it precipitates disease. Both loss of function caused by reduced C9orf72 transcript levels, and gain of function mechanisms, triggered by the production of repetitive sense and antisense RNA and dipeptide repeat proteins, are thought to contribute to the toxicity. Drosophila models, with their unrivaled genetic tractability and short lifespan, have played a key role in developing our understanding of C9orf72-related FTD/ALS. There is no C9orf72 homolog in fly, and although this precludes investigations into loss of function toxicity, it is useful for elucidating mechanisms underpinning gain of function toxicity. To date there are a range of Drosophila C9orf72 models, encompassing different aspects of gain of function toxicity. In addition to pure repeat transgenes, which produce both repeat RNA and dipeptide repeat proteins (DPRs), RNA only models and DPR models have been generated to unpick the individual contributions of RNA and each dipeptide repeat protein to C9orf72 toxicity. In this review, we discuss how Drosophila models have shaped our understanding of C9orf72 gain of function toxicity, and address opportunities to utilize these models for further research.
Collapse
Affiliation(s)
- Joanne L Sharpe
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Nikki S Harper
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, United Kingdom
| | - Duncan R Garner
- Sheffield Institute for Translational Neuroscience, The University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, The University of Sheffield, Sheffield, United Kingdom
| | - Ryan J H West
- Sheffield Institute for Translational Neuroscience, The University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, The University of Sheffield, Sheffield, United Kingdom
| |
Collapse
|
24
|
Sankaranarayanan M, Emenecker RJ, Wilby EL, Jahnel M, Trussina IREA, Wayland M, Alberti S, Holehouse AS, Weil TT. Adaptable P body physical states differentially regulate bicoid mRNA storage during early Drosophila development. Dev Cell 2021; 56:2886-2901.e6. [PMID: 34655524 PMCID: PMC8555633 DOI: 10.1016/j.devcel.2021.09.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Revised: 07/22/2021] [Accepted: 09/23/2021] [Indexed: 01/01/2023]
Abstract
Ribonucleoprotein condensates can exhibit diverse physical states in vitro and in vivo. Despite considerable progress, the relevance of condensate physical states for in vivo biological function remains limited. Here, we investigated the physical properties of processing bodies (P bodies) and their impact on mRNA storage in mature Drosophila oocytes. We show that the conserved DEAD-box RNA helicase Me31B forms viscous P body condensates, which adopt an arrested physical state. We demonstrate that structurally distinct proteins and protein-protein interactions, together with RNA, regulate the physical properties of P bodies. Using live imaging and in situ hybridization, we show that the arrested state and integrity of P bodies support the storage of bicoid (bcd) mRNA and that egg activation modulates P body properties, leading to the release of bcd for translation in the early embryo. Together, this work provides an example of how physical states of condensates regulate cellular function in development.
Collapse
Affiliation(s)
- M Sankaranarayanan
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
| | - Ryan J Emenecker
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Elise L Wilby
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Marcus Jahnel
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Irmela R E A Trussina
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Matt Wayland
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Simon Alberti
- Center for Molecular and Cellular Bioengineering, Biotechnology Center, Technische Universität Dresden, Tatzberg 47/49, 01307 Dresden, Germany
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems, Washington University in St. Louis, 1 Brookings Drive, St. Louis, MO 63130, USA
| | - Timothy T Weil
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
| |
Collapse
|
25
|
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.
Collapse
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.
| |
Collapse
|
26
|
Aledo JC. The Role of Methionine Residues in the Regulation of Liquid-Liquid Phase Separation. Biomolecules 2021; 11:biom11081248. [PMID: 34439914 PMCID: PMC8394241 DOI: 10.3390/biom11081248] [Citation(s) in RCA: 3] [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: 07/24/2021] [Revised: 08/12/2021] [Accepted: 08/18/2021] [Indexed: 02/07/2023] Open
Abstract
Membraneless organelles are non-stoichiometric supramolecular structures in the micron scale. These structures can be quickly assembled/disassembled in a regulated fashion in response to specific stimuli. Membraneless organelles contribute to the spatiotemporal compartmentalization of the cell, and they are involved in diverse cellular processes often, but not exclusively, related to RNA metabolism. Liquid-liquid phase separation, a reversible event involving demixing into two distinct liquid phases, provides a physical framework to gain insights concerning the molecular forces underlying the process and how they can be tuned according to the cellular needs. Proteins able to undergo phase separation usually present a modular architecture, which favors a multivalency-driven demixing. We discuss the role of low complexity regions in establishing networks of intra- and intermolecular interactions that collectively control the phase regime. Post-translational modifications of the residues present in these domains provide a convenient strategy to reshape the residue-residue interaction networks that determine the dynamics of phase separation. Focus will be placed on those proteins with low complexity domains exhibiting a biased composition towards the amino acid methionine and the prominent role that reversible methionine sulfoxidation plays in the assembly/disassembly of biomolecular condensates.
Collapse
Affiliation(s)
- Juan Carlos Aledo
- Departamento de Biología Molecular y Bioquímica, Facultad de Ciencias, Universidad de Málaga, 29071 Málaga, Spain
| |
Collapse
|
27
|
Cendelin J, Cvetanovic M, Gandelman M, Hirai H, Orr HT, Pulst SM, Strupp M, Tichanek F, Tuma J, Manto M. Consensus Paper: Strengths and Weaknesses of Animal Models of Spinocerebellar Ataxias and Their Clinical Implications. THE CEREBELLUM 2021; 21:452-481. [PMID: 34378174 DOI: 10.1007/s12311-021-01311-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/21/2021] [Indexed: 01/02/2023]
Abstract
Spinocerebellar ataxias (SCAs) represent a large group of hereditary degenerative diseases of the nervous system, in particular the cerebellum, and other systems that manifest with a variety of progressive motor, cognitive, and behavioral deficits with the leading symptom of cerebellar ataxia. SCAs often lead to severe impairments of the patient's functioning, quality of life, and life expectancy. For SCAs, there are no proven effective pharmacotherapies that improve the symptoms or substantially delay disease progress, i.e., disease-modifying therapies. To study SCA pathogenesis and potential therapies, animal models have been widely used and are an essential part of pre-clinical research. They mainly include mice, but also other vertebrates and invertebrates. Each animal model has its strengths and weaknesses arising from model animal species, type of genetic manipulation, and similarity to human diseases. The types of murine and non-murine models of SCAs, their contribution to the investigation of SCA pathogenesis, pathological phenotype, and therapeutic approaches including their advantages and disadvantages are reviewed in this paper. There is a consensus among the panel of experts that (1) animal models represent valuable tools to improve our understanding of SCAs and discover and assess novel therapies for this group of neurological disorders characterized by diverse mechanisms and differential degenerative progressions, (2) thorough phenotypic assessment of individual animal models is required for studies addressing therapeutic approaches, (3) comparative studies are needed to bring pre-clinical research closer to clinical trials, and (4) mouse models complement cellular and invertebrate models which remain limited in terms of clinical translation for complex neurological disorders such as SCAs.
Collapse
Affiliation(s)
- Jan Cendelin
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic. .,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.
| | - Marija Cvetanovic
- Department of Neuroscience, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Mandi Gandelman
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Hirokazu Hirai
- Department of Neurophysiology and Neural Repair, Gunma University Graduate School of Medicine, 3-39-22, Gunma, 371-8511, Japan.,Viral Vector Core, Gunma University Initiative for Advanced Research (GIAR), Gunma, 371-8511, Japan
| | - Harry T Orr
- Department of Laboratory Medicine and Pathology, Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Stefan M Pulst
- Department of Neurology, University of Utah, 175 North Medical Drive East, Salt Lake City, UT, 84132, USA
| | - Michael Strupp
- Department of Neurology and German Center for Vertigo and Balance Disorders, Hospital of the Ludwig-Maximilians University, Munich, Campus Grosshadern, Marchioninistr. 15, 81377, Munich, Germany
| | - Filip Tichanek
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,Laboratory of Neurodegenerative Disorders, Biomedical Center, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic
| | - Jan Tuma
- Department of Pathophysiology, Faculty of Medicine in Pilsen, Charles University, alej Svobody 75, 323 00, Plzen, Czech Republic.,The Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, MC 7843, San Antonio, TX, 78229, USA
| | - Mario Manto
- Unité des Ataxies Cérébelleuses, Service de Neurologie, CHU-Charleroi, Charleroi, Belgium.,Service des Neurosciences, Université de Mons, UMons, Mons, Belgium
| |
Collapse
|
28
|
Dorone Y, Boeynaems S, Flores E, Jin B, Hateley S, Bossi F, Lazarus E, Pennington JG, Michiels E, De Decker M, Vints K, Baatsen P, Bassel GW, Otegui MS, Holehouse AS, Exposito-Alonso M, Sukenik S, Gitler AD, Rhee SY. A prion-like protein regulator of seed germination undergoes hydration-dependent phase separation. Cell 2021; 184:4284-4298.e27. [PMID: 34233164 PMCID: PMC8513799 DOI: 10.1016/j.cell.2021.06.009] [Citation(s) in RCA: 82] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Revised: 03/22/2021] [Accepted: 06/04/2021] [Indexed: 12/22/2022]
Abstract
Many organisms evolved strategies to survive desiccation. Plant seeds protect dehydrated embryos from various stressors and can lay dormant for millennia. Hydration is the key trigger to initiate germination, but the mechanism by which seeds sense water remains unresolved. We identified an uncharacterized Arabidopsis thaliana prion-like protein we named FLOE1, which phase separates upon hydration and allows the embryo to sense water stress. We demonstrate that biophysical states of FLOE1 condensates modulate its biological function in vivo in suppressing seed germination under unfavorable environments. We find intragenic, intraspecific, and interspecific natural variation in FLOE1 expression and phase separation and show that intragenic variation is associated with adaptive germination strategies in natural populations. This combination of molecular, organismal, and ecological studies uncovers FLOE1 as a tunable environmental sensor with direct implications for the design of drought-resistant crops, in the face of climate change.
Collapse
Affiliation(s)
- Yanniv Dorone
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Steven Boeynaems
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Eduardo Flores
- Department of Chemistry and Chemical Biology, UC Merced, Merced, CA 95340, USA
| | - Benjamin Jin
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Shannon Hateley
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Flavia Bossi
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Elena Lazarus
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA
| | - Janice G Pennington
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI 53706, USA
| | - Emiel Michiels
- EM-platform@VIB Bio Imaging Core and VIB Center for Brain and Disease Research, KU Leuven, 3000 Leuven, Belgium; Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Mathias De Decker
- EM-platform@VIB Bio Imaging Core and VIB Center for Brain and Disease Research, KU Leuven, 3000 Leuven, Belgium; KU Leuven - University of Leuven, Department of Neurosciences, Experimental Neurology, and Leuven Brain Institute (LBI), 3000 Leuven, Belgium
| | - Katlijn Vints
- EM-platform@VIB Bio Imaging Core and VIB Center for Brain and Disease Research, KU Leuven, 3000 Leuven, Belgium
| | - Pieter Baatsen
- EM-platform@VIB Bio Imaging Core and VIB Center for Brain and Disease Research, KU Leuven, 3000 Leuven, Belgium
| | - George W Bassel
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Marisa S Otegui
- Center for Quantitative Cell Imaging, University of Wisconsin, Madison, WI 53706, USA; Department of Botany, University of Wisconsin, Madison, WI 53706, USA
| | - Alex S Holehouse
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA; Center for Science and Engineering of Living Systems (CSELS), Washington University in St. Louis, St. Louis, MO 63130, USA
| | - Moises Exposito-Alonso
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA; Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Shahar Sukenik
- Department of Chemistry and Chemical Biology, UC Merced, Merced, CA 95340, USA
| | - Aaron D Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Seung Y Rhee
- Department of Plant Biology, Carnegie Institution for Science, Stanford, CA 94305, USA.
| |
Collapse
|
29
|
Anderson EN, Morera AA, Kour S, Cherry JD, Ramesh N, Gleixner A, Schwartz JC, Ebmeier C, Old W, Donnelly CJ, Cheng JP, Kline AE, Kofler J, Stein TD, Pandey UB. Traumatic injury compromises nucleocytoplasmic transport and leads to TDP-43 pathology. eLife 2021; 10:e67587. [PMID: 34060470 PMCID: PMC8169113 DOI: 10.7554/elife.67587] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/14/2021] [Indexed: 12/14/2022] Open
Abstract
Traumatic brain injury (TBI) is a predisposing factor for many neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Alzheimer's disease (AD), Parkinson's disease (PD), and chronic traumatic encephalopathy (CTE). Although defects in nucleocytoplasmic transport (NCT) is reported ALS and other neurodegenerative diseases, whether defects in NCT occur in TBI remains unknown. We performed proteomic analysis on Drosophila exposed to repeated TBI and identified resultant alterations in several novel molecular pathways. TBI upregulated nuclear pore complex (NPC) and nucleocytoplasmic transport (NCT) proteins as well as alter nucleoporin stability. Traumatic injury disrupted RanGAP1 and NPC protein distribution in flies and a rat model and led to coaggregation of NPC components and TDP-43. In addition, trauma-mediated NCT defects and lethality are rescued by nuclear export inhibitors. Importantly, genetic upregulation of nucleoporins in vivo and in vitro triggered TDP-43 cytoplasmic mislocalization, aggregation, and altered solubility and reduced motor function and lifespan of animals. We also found NUP62 pathology and elevated NUP62 concentrations in postmortem brain tissues of patients with mild or severe CTE as well as co-localization of NUP62 and TDP-43 in CTE. These findings indicate that TBI leads to NCT defects, which potentially mediate the TDP-43 pathology in CTE.
Collapse
Affiliation(s)
- Eric N Anderson
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburghUnited States
| | - Andrés A Morera
- Department of Chemistry and Biochemistry, University of ArizonaTucsonUnited States
| | - Sukhleen Kour
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburghUnited States
| | - Jonathan D Cherry
- Department of Pathology and Laboratory Medicine, Boston University School of MedicineBostonUnited States
- Boston VA Healthcare SystemBostonUnited States
| | - Nandini Ramesh
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburghUnited States
| | - Amanda Gleixner
- Department of Neurobiology, University of Pittsburgh School of MedicinePittsburghUnited States
- LiveLike Lou Center for ALS Research, Brain Institute, University of Pittsburgh School of MedicinePittsburghUnited States
| | - Jacob C Schwartz
- Department of Chemistry and Biochemistry, University of ArizonaTucsonUnited States
| | - Christopher Ebmeier
- Molecular, Cellular & Developmental Biology, University of ColoradoBoulderUnited States
| | - William Old
- Molecular, Cellular & Developmental Biology, University of ColoradoBoulderUnited States
| | - Christopher J Donnelly
- Department of Neurobiology, University of Pittsburgh School of MedicinePittsburghUnited States
- LiveLike Lou Center for ALS Research, Brain Institute, University of Pittsburgh School of MedicinePittsburghUnited States
| | - Jeffrey P Cheng
- Physical Medicine & Rehabilitation; Safar Center for Resuscitation Research, University of PittsburghPittsburghUnited States
| | - Anthony E Kline
- Physical Medicine & Rehabilitation; Safar Center for Resuscitation Research, University of PittsburghPittsburghUnited States
- Center for Neuroscience; Center for the Neural Basis of Cognition; Critical Care Medicine, University of PittsburghPittsburghUnited States
| | - Julia Kofler
- Department of Pathology, University of PittsburghPittsburghUnited States
| | - Thor D Stein
- Department of Pathology and Laboratory Medicine, Boston University School of MedicineBostonUnited States
- Boston VA Healthcare SystemBostonUnited States
| | - Udai Bhan Pandey
- Department of Pediatrics, Children's Hospital of Pittsburgh, University of Pittsburgh Medical CenterPittsburghUnited States
- Department of Human Genetics, University of Pittsburgh School of Public HealthPittsburghUnited States
| |
Collapse
|
30
|
Floris E, Piras A, Dall’Asta L, Gamba A, Hirsch E, Campa CC. Physics of compartmentalization: How phase separation and signaling shape membrane and organelle identity. Comput Struct Biotechnol J 2021; 19:3225-3233. [PMID: 34141141 PMCID: PMC8190439 DOI: 10.1016/j.csbj.2021.05.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 05/15/2021] [Indexed: 11/29/2022] Open
Abstract
Compartmentalization of cellular functions is at the core of the physiology of eukaryotic cells. Recent evidences indicate that a universal organizing process - phase separation - supports the partitioning of biomolecules in distinct phases from a single homogeneous mixture, a landmark event in both the biogenesis and the maintenance of membrane and non-membrane-bound organelles. In the cell, 'passive' (non energy-consuming) mechanisms are flanked by 'active' mechanisms of separation into phases of distinct density and stoichiometry, that allow for increased partitioning flexibility and programmability. A convergence of physical and biological approaches is leading to new insights into the inner functioning of this driver of intracellular order, holding promises for future advances in both biological research and biotechnological applications.
Collapse
Affiliation(s)
- Elisa Floris
- Institute of Condensed Matter Physics and Complex Systems, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
| | - Andrea Piras
- Italian Institute for Genomic Medicine (IIGM), c/o IRCCS Candiolo, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
- Candiolo Cancer Institute, FPO - IRCCS, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
| | - Luca Dall’Asta
- Institute of Condensed Matter Physics and Complex Systems, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
- Collegio Carlo Alberto, Piazza Arbarello 8, 10122 Torino, Italy
| | - Andrea Gamba
- Institute of Condensed Matter Physics and Complex Systems, Department of Applied Science and Technology, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino, Italy
- Italian Institute for Genomic Medicine (IIGM), c/o IRCCS Candiolo, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
- Candiolo Cancer Institute, FPO - IRCCS, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), sezione di Torino, Via Giuria 1, 10125 Torino, Italy
| | - Emilio Hirsch
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Torino, Via Nizza 52, 10126 Torino, Italy
| | - Carlo C. Campa
- Italian Institute for Genomic Medicine (IIGM), c/o IRCCS Candiolo, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
- Candiolo Cancer Institute, FPO - IRCCS, Str.Prov.le 142, km 3.95, Candiolo (TO) 10060, Italy
| |
Collapse
|
31
|
Formicola N, Heim M, Dufourt J, Lancelot AS, Nakamura A, Lagha M, Besse F. Tyramine induces dynamic RNP granule remodeling and translation activation in the Drosophila brain. eLife 2021; 10:65742. [PMID: 33890854 PMCID: PMC8064753 DOI: 10.7554/elife.65742] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 04/04/2021] [Indexed: 02/06/2023] Open
Abstract
Ribonucleoprotein (RNP) granules are dynamic condensates enriched in regulatory RNA binding proteins (RBPs) and RNAs under tight spatiotemporal control. Extensive recent work has investigated the molecular principles underlying RNP granule assembly, unraveling that they form through the self-association of RNP components into dynamic networks of interactions. How endogenous RNP granules respond to external stimuli to regulate RNA fate is still largely unknown. Here, we demonstrate through high-resolution imaging of intact Drosophila brains that Tyramine induces a reversible remodeling of somatic RNP granules characterized by the decondensation of granule-enriched RBPs (e.g. Imp/ZBP1/IGF2BP) and helicases (e.g. Me31B/DDX-6/Rck). Furthermore, our functional analysis reveals that Tyramine signals both through its receptor TyrR and through the calcium-activated kinase CamkII to trigger RNP component decondensation. Finally, we uncover that RNP granule remodeling is accompanied by the rapid and specific translational activation of associated mRNAs. Thus, this work sheds new light on the mechanisms controlling cue-induced rearrangement of physiological RNP condensates.
Collapse
Affiliation(s)
- Nadia Formicola
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | - Marjorie Heim
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | - Jérémy Dufourt
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, Montpellier, France
| | - Anne-Sophie Lancelot
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| | - Akira Nakamura
- Department of Germline Development, Institute of Molecular Embryology and Genetics, and Graduate School of Pharmaceutical Sciences, Kumamoto University, Kumamoto, Japan
| | - Mounia Lagha
- Institut de Génétique Moléculaire de Montpellier, University of Montpellier, Montpellier, France
| | - Florence Besse
- Université Côte d'Azur, CNRS, Inserm, Institut de Biologie Valrose, Nice, France
| |
Collapse
|
32
|
Solomon DA, Smikle R, Reid MJ, Mizielinska S. Altered Phase Separation and Cellular Impact in C9orf72-Linked ALS/FTD. Front Cell Neurosci 2021; 15:664151. [PMID: 33967699 PMCID: PMC8096919 DOI: 10.3389/fncel.2021.664151] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Accepted: 03/19/2021] [Indexed: 12/21/2022] Open
Abstract
Since the discovery of the C9orf72 repeat expansion mutation as causative for chromosome 9-linked amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) in 2011, a multitude of cellular pathways have been implicated. However, evidence has also been accumulating for a key mechanism of cellular compartmentalization—phase separation. Liquid-liquid phase separation (LLPS) is fundamental for the formation of membraneless organelles including stress granules, the nucleolus, Cajal bodies, nuclear speckles and the central channel of the nuclear pore. Evidence has now accumulated showing that the formation and function of these membraneless organelles is impaired by both the toxic arginine rich dipeptide repeat proteins (DPRs), translated from the C9orf72 repeat RNA transcript, and the repeat RNA itself. Both the arginine rich DPRs and repeat RNA themselves undergo phase separation and disrupt the physiological phase separation of proteins involved in the formation of these liquid-like organelles. Hence abnormal phase separation may explain a number of pathological cellular phenomena associated with C9orf72-ALS/FTD. In this review article, we will discuss the principles of phase separation, phase separation of the DPRs and repeat RNA themselves and how they perturb LLPS associated with membraneless organelles and the functional consequences of this. We will then discuss how phase separation may impact the major pathological feature of C9orf72-ALS/FTD, TDP-43 proteinopathy, and how LLPS may be targeted therapeutically in disease.
Collapse
Affiliation(s)
- Daniel A Solomon
- UK Dementia Research Institute at King's College London, London, United Kingdom.,Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| | - Rebekah Smikle
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| | - Matthew J Reid
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| | - Sarah Mizielinska
- UK Dementia Research Institute at King's College London, London, United Kingdom.,Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, Maurice Wohl Clinical Neuroscience Institute, London, United Kingdom
| |
Collapse
|
33
|
Darling AL, Shorter J. Combating deleterious phase transitions in neurodegenerative disease. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2021; 1868:118984. [PMID: 33549703 PMCID: PMC7965345 DOI: 10.1016/j.bbamcr.2021.118984] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 01/21/2021] [Accepted: 01/22/2021] [Indexed: 12/11/2022]
Abstract
Protein aggregation is a hallmark of neurodegenerative diseases. However, the mechanism that induces pathogenic aggregation is not well understood. Recently, it has emerged that several of the pathological proteins found in an aggregated or mislocalized state in neurodegenerative diseases are also able to undergo liquid-liquid phase separation (LLPS) under physiological conditions. Although these phase transitions are likely important for various physiological functions, neurodegenerative disease-related mutations and conditions can alter the LLPS behavior of these proteins, which can elicit toxicity. Therefore, therapeutics that antagonize aberrant LLPS may be able to mitigate toxicity and aggregation that is ubiquitous in neurodegenerative disease. Here, we discuss the mechanisms by which aberrant protein phase transitions may contribute to neurodegenerative disease. We also outline potential therapeutic strategies to counter deleterious phases. State without borders: Membrane-less organelles and liquid-liquid phase transitions edited by Vladimir N Uversky.
Collapse
Affiliation(s)
- April L Darling
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA 19104, USA.
| |
Collapse
|
34
|
Roselli C, Ramaswami M, Boto T, Cervantes-Sandoval I. The Making of Long-Lasting Memories: A Fruit Fly Perspective. Front Behav Neurosci 2021; 15:662129. [PMID: 33859556 PMCID: PMC8042140 DOI: 10.3389/fnbeh.2021.662129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 03/08/2021] [Indexed: 11/25/2022] Open
Abstract
Understanding the nature of the molecular mechanisms underlying memory formation, consolidation, and forgetting are some of the fascinating questions in modern neuroscience. The encoding, stabilization and elimination of memories, rely on the structural reorganization of synapses. These changes will enable the facilitation or depression of neural activity in response to the acquisition of new information. In other words, these changes affect the weight of specific nodes within a neural network. We know that these plastic reorganizations require de novo protein synthesis in the context of Long-term memory (LTM). This process depends on neural activity triggered by the learned experience. The use of model organisms like Drosophila melanogaster has been proven essential for advancing our knowledge in the field of neuroscience. Flies offer an optimal combination of a more straightforward nervous system, composed of a limited number of cells, and while still displaying complex behaviors. Studies in Drosophila neuroscience, which expanded over several decades, have been critical for understanding the cellular and molecular mechanisms leading to the synaptic and behavioral plasticity occurring in the context of learning and memory. This is possible thanks to sophisticated technical approaches that enable precise control of gene expression in the fruit fly as well as neural manipulation, like chemogenetics, thermogenetics, or optogenetics. The search for the identity of genes expressed as a result of memory acquisition has been an active interest since the origins of behavioral genetics. From screenings of more or less specific candidates to broader studies based on transcriptome analysis, our understanding of the genetic control behind LTM has expanded exponentially in the past years. Here we review recent literature regarding how the formation of memories induces a rapid, extensive and, in many cases, transient wave of transcriptional activity. After a consolidation period, transcriptome changes seem more stable and likely represent the synthesis of new proteins. The complexity of the circuitry involved in memory formation and consolidation is such that there are localized changes in neural activity, both regarding temporal dynamics and the nature of neurons and subcellular locations affected, hence inducing specific temporal and localized changes in protein expression. Different types of neurons are recruited at different times into memory traces. In LTM, the synthesis of new proteins is required in specific subsets of cells. This de novo translation can take place in the somatic cytoplasm and/or locally in distinct zones of compartmentalized synaptic activity, depending on the nature of the proteins and the plasticity-inducing processes that occur. We will also review recent advances in understanding how localized changes are confined to the relevant synapse. These recent studies have led to exciting discoveries regarding proteins that were not previously involved in learning and memory processes. This invaluable information will lead to future functional studies on the roles that hundreds of new molecular actors play in modulating neural activity.
Collapse
Affiliation(s)
- Camilla Roselli
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Mani Ramaswami
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College Dublin, Dublin, Ireland.,National Centre for Biological Sciences, TIFR, Bengaluru, India
| | - Tamara Boto
- Trinity College Institute of Neuroscience, Department of Physiology, School of Medicine, Trinity College Dublin, Dublin, Ireland
| | - Isaac Cervantes-Sandoval
- Department of Biology, Georgetown University, Washington, DC, United States.,Interdisciplinary Program in Neuroscience, Georgetown University, Washington, DC, United States
| |
Collapse
|
35
|
The ATXN2 Orthologs CID3 and CID4, Act Redundantly to In-Fluence Developmental Pathways throughout the Life Cycle of Arabidopsis thaliana. Int J Mol Sci 2021; 22:ijms22063068. [PMID: 33802796 PMCID: PMC8002431 DOI: 10.3390/ijms22063068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 02/15/2021] [Accepted: 02/15/2021] [Indexed: 11/17/2022] Open
Abstract
RNA-binding proteins (RBPs) are key elements involved in post-transcriptional regulation. Ataxin-2 (ATXN2) is an evolutionarily conserved RBP protein, whose function has been studied in several model organisms, from Saccharomyces cerevisiae to the Homo sapiens. ATXN2 interacts with poly(A) binding proteins (PABP) and binds to specific sequences at the 3'UTR of target mRNAs to stabilize them. CTC-Interacting Domain3 (CID3) and CID4 are two ATXN2 orthologs present in plant genomes whose function is unknown. In the present study, phenotypical and transcriptome profiling were used to examine the role of CID3 and CID4 in Arabidopsis thaliana. We found that they act redundantly to influence pathways throughout the life cycle. cid3cid4 double mutant showed a delay in flowering time and a reduced rosette size. Transcriptome profiling revealed that key factors that promote floral transition and floral meristem identity were downregulated in cid3cid4 whereas the flowering repressor FLOWERING LOCUS C (FLC) was upregulated. Expression of key factors in the photoperiodic regulation of flowering and circadian clock pathways, were also altered in cid3cid4, as well as the expression of several transcription factors and miRNAs encoding genes involved in leaf growth dynamics. These findings reveal that ATXN2 orthologs may have a role in developmental pathways throughout the life cycle of plants.
Collapse
|
36
|
Singh A, Hulsmeier J, Kandi AR, Pothapragada SS, Hillebrand J, Petrauskas A, Agrawal K, RT K, Thiagarajan D, Jayaprakashappa D, VijayRaghavan K, Ramaswami M, Bakthavachalu B. Antagonistic roles for Ataxin-2 structured and disordered domains in RNP condensation. eLife 2021; 10:e60326. [PMID: 33689682 PMCID: PMC7946432 DOI: 10.7554/elife.60326] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 02/23/2021] [Indexed: 02/07/2023] Open
Abstract
Ataxin-2 (Atx2) is a translational control molecule mutated in spinocerebellar ataxia type II and amyotrophic lateral sclerosis. While intrinsically disordered domains (IDRs) of Atx2 facilitate mRNP condensation into granules, how IDRs work with structured domains to enable positive and negative regulation of target mRNAs remains unclear. Using the Targets of RNA-Binding Proteins Identified by Editing technology, we identified an extensive data set of Atx2-target mRNAs in the Drosophila brain and S2 cells. Atx2 interactions with AU-rich elements in 3'UTRs appear to modulate stability/turnover of a large fraction of these target mRNAs. Further genomic and cell biological analyses of Atx2 domain deletions demonstrate that Atx2 (1) interacts closely with target mRNAs within mRNP granules, (2) contains distinct protein domains that drive or oppose RNP-granule assembly, and (3) has additional essential roles outside of mRNP granules. These findings increase the understanding of neuronal translational control mechanisms and inform strategies for Atx2-based interventions under development for neurodegenerative disease.
Collapse
Affiliation(s)
- Amanjot Singh
- National Centre for Biological SciencesBangaloreIndia
| | - Joern Hulsmeier
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Arvind Reddy Kandi
- National Centre for Biological SciencesBangaloreIndia
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
| | | | - Jens Hillebrand
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Arnas Petrauskas
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Khushboo Agrawal
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
- School of Biotechnology, Amrita Vishwa Vidyapeetham UniversityKollamIndia
| | - Krishnan RT
- National Centre for Biological SciencesBangaloreIndia
| | | | | | | | - Mani Ramaswami
- National Centre for Biological SciencesBangaloreIndia
- Trinity College Institute of Neuroscience, School of Genetics and Microbiology, Smurfit Institute of Genetics and School of Natural Sciences, Trinity College DublinDublinIreland
| | - Baskar Bakthavachalu
- National Centre for Biological SciencesBangaloreIndia
- Tata Institute for Genetics and Society Centre at inStem, Bellary RoadBangaloreIndia
- School of Basic Sciences, Indian Institute of TechnologyMandiIndia
| |
Collapse
|
37
|
Lee J, Park J, Kim JH, Lee G, Park TE, Yoon KJ, Kim YK, Lim C. LSM12-EPAC1 defines a neuroprotective pathway that sustains the nucleocytoplasmic RAN gradient. PLoS Biol 2020; 18:e3001002. [PMID: 33362237 PMCID: PMC7757817 DOI: 10.1371/journal.pbio.3001002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 11/19/2020] [Indexed: 02/07/2023] Open
Abstract
Nucleocytoplasmic transport (NCT) defects have been implicated in neurodegenerative diseases such as C9ORF72-associated amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). Here, we identify a neuroprotective pathway of like-Sm protein 12 (LSM12) and exchange protein directly activated by cyclic AMP 1 (EPAC1) that sustains the nucleocytoplasmic RAN gradient and thereby suppresses NCT dysfunction by the C9ORF72-derived poly(glycine-arginine) protein. LSM12 depletion in human neuroblastoma cells aggravated poly(GR)-induced impairment of NCT and nuclear integrity while promoting the nuclear accumulation of poly(GR) granules. In fact, LSM12 posttranscriptionally up-regulated EPAC1 expression, whereas EPAC1 overexpression rescued the RAN gradient and NCT defects in LSM12-deleted cells. C9-ALS patient-derived neurons differentiated from induced pluripotent stem cells (C9-ALS iPSNs) displayed low expression of LSM12 and EPAC1. Lentiviral overexpression of LSM12 or EPAC1 indeed restored the RAN gradient, mitigated the pathogenic mislocalization of TDP-43, and suppressed caspase-3 activation for apoptosis in C9-ALS iPSNs. EPAC1 depletion biochemically dissociated RAN-importin β1 from the cytoplasmic nuclear pore complex, thereby dissipating the nucleocytoplasmic RAN gradient essential for NCT. These findings define the LSM12-EPAC1 pathway as an important suppressor of the NCT-related pathologies in C9-ALS/FTD. A post-transcriptional circuit comprising LSM12 and EPAC1 suppresses neurodegenerative pathologies in C9ORF72-associated amyotrophic lateral sclerosis by establishing the RAN gradient and sustaining nucleocytoplasmic transport.
Collapse
Affiliation(s)
- Jongbo Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jumin Park
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ji-hyung Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Giwook Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Tae-Eun Park
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Ki-Jun Yoon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | - Yoon Ki Kim
- Creative Research Initiatives Center for Molecular Biology of Translation, Korea University, Seoul, Republic of Korea
- Division of Life Sciences, Korea University, Seoul, Republic of Korea
| | - Chunghun Lim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- * E-mail:
| |
Collapse
|
38
|
Madugalle SU, Meyer K, Wang DO, Bredy TW. RNA N 6-Methyladenosine and the Regulation of RNA Localization and Function in the Brain. Trends Neurosci 2020; 43:1011-1023. [PMID: 33041062 PMCID: PMC7688512 DOI: 10.1016/j.tins.2020.09.005] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 09/01/2020] [Accepted: 09/15/2020] [Indexed: 12/17/2022]
Abstract
A major challenge in neurobiology in the 21st century is to understand how the brain adapts with experience. Activity-dependent gene expression is integral to the synaptic plasticity underlying learning and memory; however, this process cannot be explained by a simple linear trajectory of transcription to translation within a specific neuronal population. Many other regulatory mechanisms can influence RNA metabolism and the capacity of neurons to adapt. In particular, the RNA modification N6-methyladenosine (m6A) has recently been shown to regulate RNA processing through alternative splicing, RNA stability, and translation. Here, we discuss the emerging idea that m6A could also coordinate the transport, localization, and local translation of key mRNAs in learning and memory and expand on the notion of dynamic functional RNA states in the brain.
Collapse
Affiliation(s)
- Sachithrani U Madugalle
- Cognitive Neuroepigenetics Laboratory, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
| | - Kate Meyer
- Department of Biochemistry, Duke University School of Medicine, Durham, NC, USA; Department of Neurobiology, Duke University School of Medicine, Durham, NC, USA
| | - Dan Ohtan Wang
- Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University, Kyoto, Japan; Wuya College of Innovation, Shenyang Pharmaceutical University, Shenyang, China
| | - Timothy W Bredy
- Cognitive Neuroepigenetics Laboratory, Queensland Brain Institute, The University of Queensland, Brisbane, QLD, Australia.
| |
Collapse
|
39
|
Muthunayake NS, Tomares DT, Childers WS, Schrader JM. Phase-separated bacterial ribonucleoprotein bodies organize mRNA decay. WILEY INTERDISCIPLINARY REVIEWS. RNA 2020; 11:e1599. [PMID: 32445438 PMCID: PMC7554086 DOI: 10.1002/wrna.1599] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 04/16/2020] [Accepted: 04/17/2020] [Indexed: 01/12/2023]
Abstract
In bacteria, mRNA decay is controlled by megadalton scale macromolecular assemblies called, "RNA degradosomes," composed of nucleases and other RNA decay associated proteins. Recent advances in bacterial cell biology have shown that RNA degradosomes can assemble into phase-separated structures, termed bacterial ribonucleoprotein bodies (BR-bodies), with many analogous properties to eukaryotic processing bodies and stress granules. This review will highlight the functional role that BR-bodies play in the mRNA decay process through its organization into a membraneless organelle in the bacterial cytoplasm. This review will also highlight the phylogenetic distribution of BR-bodies across bacterial species, which suggests that these phase-separated structures are broadly distributed across bacteria, and in evolutionarily related mitochondria and chloroplasts. This article is categorized under: RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Export and Localization > RNA Localization RNA Turnover and Surveillance > Regulation of RNA Stability.
Collapse
Affiliation(s)
| | - Dylan T Tomares
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - W Seth Childers
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Jared M Schrader
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| |
Collapse
|
40
|
Cha IJ, Lee D, Park SS, Chung CG, Kim SY, Jo MG, Kim SY, Lee BH, Lee YS, Lee SB. Ataxin-2 Dysregulation Triggers a Compensatory Fragile X Mental Retardation Protein Decrease in Drosophila C4da Neurons. Mol Cells 2020; 43:870-879. [PMID: 33115979 PMCID: PMC7604024 DOI: 10.14348/molcells.2020.0158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 09/24/2020] [Accepted: 09/24/2020] [Indexed: 12/19/2022] Open
Abstract
Dendrites require precise and timely delivery of protein substrates to distal areas to ensure the correct morphology and function of neurons. Many of these protein substrates are supplied in the form of ribonucleoprotein (RNP) complex consisting of RNA-binding proteins (RBPs) and mRNAs, which are subsequently translated in distal dendritic areas. It remains elusive, however, whether key RBPs supply mRNA according to local demands individually or in a coordinated manner. In this study, we investigated how Drosophila sensory neurons respond to the dysregulation of a disease-associated RBP, Ataxin-2 (ATX2), which leads to dendritic defects. We found that ATX2 plays a crucial role in spacing dendritic branches for the optimal dendritic receptive fields in Drosophila class IV dendritic arborization (C4da) neurons, where both expression level and subcellular location of ATX2 contribute significantly to this effect. We showed that translational upregulation through the expression of eukaryotic translation initiation factor 4E (eIF4E) further enhanced the ATX2-induced dendritic phenotypes. Additionally, we found that the expression level of another disease-associated RBP, fragile X mental retardation protein (FMRP), decreased in both cell bodies and dendrites when neurons were faced with aberrant upregulation of ATX2. Finally, we revealed that the PAM2 motif of ATX2, which mediates its interaction with poly(A)-binding protein (PABP), is potentially necessary for the decrease of FMRP in certain neuronal stress conditions. Collectively, our data suggest that dysregulation of RBPs triggers a compensatory regulation of other functionally-overlapping RBPs to minimize RBP dysregulation-associated aberrations that hinder neuronal homeostasis in dendrites.
Collapse
Affiliation(s)
- In Jun Cha
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Davin Lee
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Sung Soon Park
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Chang Geon Chung
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Seung Yeon Kim
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Min Gu Jo
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Seung Yeol Kim
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
| | - Byung-Hoon Lee
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Department of New Biology, DGIST, Daegu 42988, Korea
| | - Young-Sam Lee
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Department of New Biology, DGIST, Daegu 42988, Korea
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu 42988, Korea
| | - Sung Bae Lee
- Department of Brain & Cognitive Sciences, Daegu Gyeongbuk Institute of Science & Technology (DGIST), Daegu 42988, Korea
- Protein Dynamics-Based Proteotoxicity Control Laboratory, Basic Research Lab, DGIST, Daegu 42988, Korea
- Well Aging Research Center, Division of Biotechnology, DGIST, Daegu 42988, Korea
| |
Collapse
|
41
|
Yoshizawa T, Matsumura H. Effect of nuclear import receptors on liquid-liquid phase separation. Biophys Physicobiol 2020; 17:25-29. [PMID: 33110735 PMCID: PMC7550251 DOI: 10.2142/biophysico.bsj-2019052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2019] [Accepted: 02/07/2020] [Indexed: 02/01/2023] Open
Abstract
Low-complexity (LC) sequences, regions that are predominantly made up of limited amino acids, are often observed in eukaryotic nuclear proteins. The role of these LC sequences has remained unclear for decades. Recent studies have shown that LC sequences are important in the formation of membrane-less organelles via liquid–liquid phase separation (LLPS). The RNA binding protein, fused in sarcoma (FUS), is the most widely studied of the proteins that undergo LLPS. It forms droplets, fibers, or hydrogels using its LC sequences. The N-terminal LC sequence of FUS is made up of Ser, Tyr, Gly, and Gln, which form a labile cross-β polymer core while the C-terminal Arg-Gly-Gly repeats accelerate LLPS. Normally, FUS localizes to the nucleus via the nuclear import receptor karyopherin β2 (Kapβ2) with the help of its C-terminal proline-tyrosine nuclear localization signal (PY-NLS). Recent findings revealed that Kapβ2 blocks FUS mediated LLPS, suggesting that Kapβ2 is not only a transport protein but also a chaperone which regulates LLPS during the formation of membrane-less organelles. In this review, we discuss the effects of the nuclear import receptors on LLPS.
Collapse
Affiliation(s)
- Takuya Yoshizawa
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hiroyoshi Matsumura
- College of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| |
Collapse
|
42
|
Watanabe R, Higashi S, Nonaka T, Kawakami I, Oshima K, Niizato K, Akiyama H, Yoshida M, Hasegawa M, Arai T. Intracellular dynamics of Ataxin-2 in the human brains with normal and frontotemporal lobar degeneration with TDP-43 inclusions. Acta Neuropathol Commun 2020; 8:176. [PMID: 33115537 PMCID: PMC7594343 DOI: 10.1186/s40478-020-01055-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 10/10/2020] [Indexed: 12/15/2022] Open
Abstract
TAR DNA-binding protein of 43 kDa (TDP-43) is a major component of intracellular aggregates formed in brains of the patients with frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS), which are correctively referred to as TDP-43 proteinopathies. A link between Ataxin-2 (ATXN2) and TDP-43 proteinopathies was established when intermediate CAG repeat expansions of ATXN2 gene were found to be associated with ALS and it was shown that ATXN2 modifies TDP-43 toxicity. Although ATXN2's contribution to TDP-43 proteinopathies has been mostly studied in ALS, recent studies have shown that intermediate repeat expansions of ATXN2 also influence the phenotype of FTLD by an unknown mechanism. To address this issue, we immunohistochemically and biochemically analyzed the intracellular dynamics of ATXN2 in brains of normal controls and FTLD-TDP cases. The immunohistochemical studies revealed that ATXN2 localized in the neuronal cytoplasm and proximal dendrites, and expressed widely and uniformly in normal human brains. A semi-quantitative immunofluorescent analysis of normal brains revealed that the cytoplasmic ATXN2 strongly associates with ribosomal protein S6 and poly-A binding protein 1 and partially overlaps with the endoplasmic reticulum marker Calnexin, suggesting a major role of ATXN2 in protein synthesis. The results of immunohistochemical and biochemical analyses of brains from FTLD-TDP cases showed the colocalization of ATXN2 and phosphorylated TDP-43 in the dystrophic neurites and the neuronal cytoplasmic inclusions in the hippocampal region, and a significant reduction of ATXN2 protein compared to controls. These results suggest that ATXN2 is involved in the pathological process of FTLD-TDP. It remains to be clarified whether reduced ATXN2 expression induces neurodegeneration by impairing protein synthesis or plays a neuroprotective role by attenuating the toxicity of TDP-43 aggregates in FTLD-TDP and other TDP-43 proteinopathies.
Collapse
Affiliation(s)
- Ryohei Watanabe
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Shinji Higashi
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
- Department of Psychiatry, Tokyo Medical University Ibaraki Medical Center, 3-20-1 Chuo, Ami, Inashiki, Ibaraki Japan
| | - Takashi Nonaka
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
| | - Ito Kawakami
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
- Brain Bank for Aging Research, Department of Neuropathology, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakaecho, Itabashi, Tokyo Japan
| | - Kenichi Oshima
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Kazuhiro Niizato
- Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, 2-1-1 Kamikitazawa, Setagaya, Tokyo Japan
| | - Haruhiko Akiyama
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
- Department of Clinical Research, Yokohama Brain and Spine Center, 1-2-1 Takigashira, Isogo, Yokohama, Kanagawa Japan
| | - Mari Yoshida
- Institute for Medical Science of Aging, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi Japan
| | - Masato Hasegawa
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamikitazawa, Setagaya, Tokyo Japan
| | - Tetsuaki Arai
- Department of Psychiatry, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki Japan
| |
Collapse
|
43
|
Omer A, Patel D, Moran JL, Lian XJ, Di Marco S, Gallouzi IE. Autophagy and heat-shock response impair stress granule assembly during cellular senescence. Mech Ageing Dev 2020; 192:111382. [PMID: 33049246 DOI: 10.1016/j.mad.2020.111382] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 09/21/2020] [Accepted: 10/05/2020] [Indexed: 01/08/2023]
Abstract
Stress granules (SGs) are membraneless organelles formed in response to insult. These granules are related to pathological granules found in age-related neurogenerative diseases such as Parkinson's and Alzheimer's. Previously, we demonstrated that senescent cells, which accumulate with age, exposed to chronic oxidative stress, are unable to form SGs. Here, we show that the senescent cells' inability to form SGs correlates with an upregulation in both the heat-shock response and autophagy pathways, both of which are well-established promoters of SG disassembly. Our data also reveals that the knockdown of HSP70 and ATG5, important components of the heat-shock response and autophagy pathways, respectively, restores the number of SGs formed in senescent cells exposed to chronic oxidative stress. Surprisingly, under these conditions, the depletion of HSP70 or ATG5 did not affect the clearance of these SGs during their recovery from chronic stress. These data reveal that senescent cells possess a unique heat-shock and autophagy-dependent ability to impair the formation of SGs in response to chronic stress, thereby expanding the existing understanding of SG dynamics in senescent cells and their potential contribution to age-related neurodegenerative diseases.
Collapse
Affiliation(s)
- Amr Omer
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada.
| | - Devang Patel
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Julian Lucas Moran
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Xian Jin Lian
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Sergio Di Marco
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada
| | - Imed-Eddine Gallouzi
- McGill University, Department of Biochemistry, Rosalind and Morris Goodman Cancer Centre, Montreal, Quebec, Canada.
| |
Collapse
|
44
|
Phase separation by ssDNA binding protein controlled via protein-protein and protein-DNA interactions. Proc Natl Acad Sci U S A 2020; 117:26206-26217. [PMID: 33020264 PMCID: PMC7584906 DOI: 10.1073/pnas.2000761117] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Cells must rapidly and efficiently react to DNA damage to avoid its harmful consequences. Here we report a molecular mechanism that gives rise to a model of how bacterial cells mobilize DNA repair proteins for timely response to genomic stress and initiation of DNA repair upon exposure of single-stranded DNA. We found that bacterial single-stranded DNA binding protein (SSB), a central player in genome metabolism, can undergo dynamic phase separation under physiological conditions. SSB condensates can store a wide array of DNA repair proteins that specifically interact with SSB. However, elevated levels of single-stranded DNA during genomic stress can dissolve SSB condensates, enabling rapid mobilization of SSB and SSB-interacting proteins to sites of DNA damage. Bacterial single-stranded (ss)DNA-binding proteins (SSB) are essential for the replication and maintenance of the genome. SSBs share a conserved ssDNA-binding domain, a less conserved intrinsically disordered linker (IDL), and a highly conserved C-terminal peptide (CTP) motif that mediates a wide array of protein−protein interactions with DNA-metabolizing proteins. Here we show that the Escherichia coli SSB protein forms liquid−liquid phase-separated condensates in cellular-like conditions through multifaceted interactions involving all structural regions of the protein. SSB, ssDNA, and SSB-interacting molecules are highly concentrated within the condensates, whereas phase separation is overall regulated by the stoichiometry of SSB and ssDNA. Together with recent results on subcellular SSB localization patterns, our results point to a conserved mechanism by which bacterial cells store a pool of SSB and SSB-interacting proteins. Dynamic phase separation enables rapid mobilization of this protein pool to protect exposed ssDNA and repair genomic loci affected by DNA damage.
Collapse
|
45
|
Pessina F, Gioia U, Brandi O, Farina S, Ceccon M, Francia S, d'Adda di Fagagna F. DNA Damage Triggers a New Phase in Neurodegeneration. Trends Genet 2020; 37:337-354. [PMID: 33020022 DOI: 10.1016/j.tig.2020.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 08/28/2020] [Accepted: 09/03/2020] [Indexed: 12/21/2022]
Abstract
Subcellular compartmentalization contributes to the organization of a plethora of molecular events occurring within cells. This can be achieved in membraneless organelles generated through liquid-liquid phase separation (LLPS), a demixing process that separates and concentrates cellular reactions. RNA is often a critical factor in mediating LLPS. Recent evidence indicates that DNA damage response foci are membraneless structures formed via LLPS and modulated by noncoding transcripts synthesized at DNA damage sites. Neurodegeneration is often associated with DNA damage, and dysfunctional LLPS events can lead to the formation of toxic aggregates. In this review, we discuss those gene products involved in neurodegeneration that undergo LLPS and their involvement in the DNA damage response.
Collapse
Affiliation(s)
- Fabio Pessina
- IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy
| | - Ubaldo Gioia
- IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy
| | - Ornella Brandi
- Istituto di Genetica Molecolare 'Luigi Luca Cavalli-Sforza' CNR - Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy
| | - Stefania Farina
- Istituto di Genetica Molecolare 'Luigi Luca Cavalli-Sforza' CNR - Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy; University School for Advanced Studies IUSS, 27100 Pavia, Italy
| | - Marta Ceccon
- IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy
| | - Sofia Francia
- IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy; Istituto di Genetica Molecolare 'Luigi Luca Cavalli-Sforza' CNR - Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy.
| | - Fabrizio d'Adda di Fagagna
- IFOM Foundation - FIRC Institute of Molecular Oncology Foundation, 20139 Milan, Italy; Istituto di Genetica Molecolare 'Luigi Luca Cavalli-Sforza' CNR - Consiglio Nazionale delle Ricerche, 27100 Pavia, Italy.
| |
Collapse
|
46
|
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.
Collapse
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
| |
Collapse
|
47
|
Pakravan D, Orlando G, Bercier V, Van Den Bosch L. Role and therapeutic potential of liquid-liquid phase separation in amyotrophic lateral sclerosis. J Mol Cell Biol 2020; 13:15-28. [PMID: 32976566 PMCID: PMC8036000 DOI: 10.1093/jmcb/mjaa049] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 07/24/2020] [Accepted: 08/27/2020] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a late-onset neurodegenerative disease selectively affecting motor neurons, leading to progressive paralysis. Although most cases are sporadic, ∼10% are familial. Similar proteins are found in aggregates in sporadic and familial ALS, and over the last decade, research has been focused on the underlying nature of this common pathology. Notably, TDP-43 inclusions are found in almost all ALS patients, while FUS inclusions have been reported in some familial ALS patients. Both TDP-43 and FUS possess ‘low-complexity domains’ (LCDs) and are considered as ‘intrinsically disordered proteins’, which form liquid droplets in vitro due to the weak interactions caused by the LCDs. Dysfunctional ‘liquid–liquid phase separation’ (LLPS) emerged as a new mechanism linking ALS-related proteins to pathogenesis. Here, we review the current state of knowledge on ALS-related gene products associated with a proteinopathy and discuss their status as LLPS proteins. In addition, we highlight the therapeutic potential of targeting LLPS for treating ALS.
Collapse
Affiliation(s)
- Donya Pakravan
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), KU Leuven—University of Leuven, 3000 Leuven, Belgium
- Laboratory of Neurobiology, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Gabriele Orlando
- Switch Laboratory, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Valérie Bercier
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), KU Leuven—University of Leuven, 3000 Leuven, Belgium
- Laboratory of Neurobiology, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
| | - Ludo Van Den Bosch
- Department of Neurosciences, Experimental Neurology and Leuven Brain Institute (LBI), KU Leuven—University of Leuven, 3000 Leuven, Belgium
- Laboratory of Neurobiology, VIB-KU Leuven Center for Brain & Disease Research, 3000 Leuven, Belgium
- Correspondence to: Ludo Van Den Bosch, E-mail:
| |
Collapse
|
48
|
Tauber D, Tauber G, Parker R. Mechanisms and Regulation of RNA Condensation in RNP Granule Formation. Trends Biochem Sci 2020; 45:764-778. [PMID: 32475683 PMCID: PMC7211619 DOI: 10.1016/j.tibs.2020.05.002] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/20/2020] [Accepted: 05/05/2020] [Indexed: 01/01/2023]
Abstract
Ribonucleoprotein (RNP) granules are RNA-protein assemblies that are involved in multiple aspects of RNA metabolism and are linked to memory, development, and disease. Some RNP granules form, in part, through the formation of intermolecular RNA-RNA interactions. In vitro, such trans RNA condensation occurs readily, suggesting that cells require mechanisms to modulate RNA-based condensation. We assess the mechanisms of RNA condensation and how cells modulate this phenomenon. We propose that cells control RNA condensation through ATP-dependent processes, static RNA buffering, and dynamic post-translational mechanisms. Moreover, perturbations in these mechanisms can be involved in disease. This reveals multiple cellular mechanisms of kinetic and thermodynamic control that maintain the proper distribution of RNA molecules between dispersed and condensed forms.
Collapse
Affiliation(s)
- Devin Tauber
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80308, USA
| | - Gabriel Tauber
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO 80308, USA; Howard Hughes Medical Institute, University of Colorado Boulder, Boulder, CO 80308, USA.
| |
Collapse
|
49
|
Nil Z, Hervás R, Gerbich T, Leal P, Yu Z, Saraf A, Sardiu M, Lange JJ, Yi K, Unruh J, Slaughter B, Si K. Amyloid-like Assembly Activates a Phosphatase in the Developing Drosophila Embryo. Cell 2020; 178:1403-1420.e21. [PMID: 31491385 DOI: 10.1016/j.cell.2019.08.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 05/07/2019] [Accepted: 08/08/2019] [Indexed: 12/30/2022]
Abstract
Prion-like proteins can assume distinct conformational and physical states in the same cell. Sequence analysis suggests that prion-like proteins are prevalent in various species; however, it remains unclear what functional space they occupy in multicellular organisms. Here, we report the identification of a prion-like protein, Herzog (CG5830), through a multimodal screen in Drosophila melanogaster. Herzog functions as a membrane-associated phosphatase and controls embryonic patterning, likely being involved in TGF-β/BMP and FGF/EGF signaling pathways. Remarkably, monomeric Herzog is enzymatically inactive and becomes active upon amyloid-like assembly. The prion-like domain of Herzog is necessary for both its assembly and membrane targeting. Removal of the prion-like domain impairs activity, while restoring assembly on the membrane using a heterologous prion-like domain and membrane-targeting motif can restore phosphatase activity. This study provides an example of a prion-like domain that allows an enzyme to gain essential functionality via amyloid-like assembly to control animal development.
Collapse
Affiliation(s)
- Zelha Nil
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
| | - Rubén Hervás
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Therese Gerbich
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Paulo Leal
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Zulin Yu
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Anita Saraf
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Mihaela Sardiu
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Jeffrey J Lange
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Kexi Yi
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Jay Unruh
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Brian Slaughter
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA
| | - Kausik Si
- Stowers Institute for Medical Research, 1000E 50(th) Street, Kansas City, MO 64110, USA; Department of Molecular and Integrative Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA.
| |
Collapse
|
50
|
Buddika K, Ariyapala IS, Hazuga MA, Riffert D, Sokol NS. Canonical nucleators are dispensable for stress granule assembly in Drosophila intestinal progenitors. J Cell Sci 2020; 133:jcs243451. [PMID: 32265270 PMCID: PMC7325430 DOI: 10.1242/jcs.243451] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Accepted: 03/26/2020] [Indexed: 12/18/2022] Open
Abstract
Stressed cells downregulate translation initiation and assemble membrane-less foci termed stress granules (SGs). Although SGs have been extensively characterized in cultured cells, the existence of such structures in stressed adult stem cell pools remains poorly characterized. Here, we report that the Drosophila orthologs of the mammalian SG components AGO1, ATX2, CAPRIN, eIF4E, FMRP, G3BP, LIN-28, PABP and TIAR are enriched in adult fly intestinal progenitor cells, where they accumulate in small cytoplasmic messenger ribonucleoprotein complexes (mRNPs). Treatment with sodium arsenite or rapamycin reorganized these mRNPs into large cytoplasmic granules. Formation of these intestinal progenitor stress granules (IPSGs) depended on polysome disassembly, led to translational downregulation and was reversible. Although the canonical SG nucleators ATX2 and G3BP were sufficient for IPSG formation in the absence of stress, neither of them, nor TIAR, either individually or collectively, were required for stress-induced IPSG formation. This work therefore finds that IPSGs do not assemble via a canonical mechanism, raising the possibility that other stem cell populations employ a similar stress-response mechanism.
Collapse
Affiliation(s)
- Kasun Buddika
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | | | - Mary A Hazuga
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Derek Riffert
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Nicholas S Sokol
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| |
Collapse
|