1
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Tseng YJ, Krans A, Malik I, Deng X, Yildirim E, Ovunc S, Tank EMH, Jansen-West K, Kaufhold R, Gomez NB, Sher R, Petrucelli L, Barmada SJ, Todd PK. Ribosomal quality control factors inhibit repeat-associated non-AUG translation from GC-rich repeats. Nucleic Acids Res 2024:gkae137. [PMID: 38412259 DOI: 10.1093/nar/gkae137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 02/05/2024] [Accepted: 02/19/2024] [Indexed: 02/29/2024] Open
Abstract
A GGGGCC (G4C2) hexanucleotide repeat expansion in C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD), while a CGG trinucleotide repeat expansion in FMR1 leads to the neurodegenerative disorder Fragile X-associated tremor/ataxia syndrome (FXTAS). These GC-rich repeats form RNA secondary structures that support repeat-associated non-AUG (RAN) translation of toxic proteins that contribute to disease pathogenesis. Here we assessed whether these same repeats might trigger stalling and interfere with translational elongation. We find that depletion of ribosome-associated quality control (RQC) factors NEMF, LTN1 and ANKZF1 markedly boost RAN translation product accumulation from both G4C2 and CGG repeats while overexpression of these factors reduces RAN production in both reporter assays and C9ALS/FTD patient iPSC-derived neurons. We also detected partially made products from both G4C2 and CGG repeats whose abundance increased with RQC factor depletion. Repeat RNA sequence, rather than amino acid content, is central to the impact of RQC factor depletion on RAN translation-suggesting a role for RNA secondary structure in these processes. Together, these findings suggest that ribosomal stalling and RQC pathway activation during RAN translation inhibits the generation of toxic RAN products. We propose augmenting RQC activity as a therapeutic strategy in GC-rich repeat expansion disorders.
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Affiliation(s)
- Yi-Ju Tseng
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Ann Arbor Veterans Administration Healthcare, Ann Arbor, MI 48109, USA
| | - Indranil Malik
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Biotechnology, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, 502284 Telangana, India
| | - Xiexiong Deng
- Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI 48109, USA
| | - Evrim Yildirim
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Sinem Ovunc
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Elizabeth M H Tank
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Karen Jansen-West
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL 32224, USA
| | - Ross Kaufhold
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Nicolas B Gomez
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI 48109, USA
| | - Roger Sher
- Department of Neurobiology and Behavior & Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY 11794, USA
| | | | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109, USA
- Ann Arbor Veterans Administration Healthcare, Ann Arbor, MI 48109, USA
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2
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Ito H, Machida K, Hasumi M, Ueyama M, Nagai Y, Imataka H, Taguchi H. Reconstitution of C9orf72 GGGGCC repeat-associated non-AUG translation with purified human translation factors. Sci Rep 2023; 13:22826. [PMID: 38129650 PMCID: PMC10739749 DOI: 10.1038/s41598-023-50188-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Accepted: 12/16/2023] [Indexed: 12/23/2023] Open
Abstract
Nucleotide repeat expansion of GGGGCC (G4C2) in the non-coding region of C9orf72 is the most common genetic cause underlying amyotrophic lateral sclerosis and frontotemporal dementia. Transcripts harboring this repeat expansion undergo the translation of dipeptide repeats via a non-canonical process known as repeat-associated non-AUG (RAN) translation. In order to ascertain the essential components required for RAN translation, we successfully recapitulated G4C2-RAN translation using an in vitro reconstituted translation system comprising human factors, namely the human PURE system. Our findings conclusively demonstrate that the presence of fundamental translation factors is sufficient to mediate the elongation from the G4C2 repeat. Furthermore, the initiation mechanism proceeded in a 5' cap-dependent manner, independent of eIF2A or eIF2D. In contrast to cell lysate-mediated RAN translation, where longer G4C2 repeats enhanced translation, we discovered that the expansion of the G4C2 repeats inhibited translation elongation using the human PURE system. These results suggest that the repeat RNA itself functions as a repressor of RAN translation. Taken together, our utilization of a reconstituted RAN translation system employing minimal factors represents a distinctive and potent approach for elucidating the intricacies underlying RAN translation mechanism.
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Grants
- JPMJFS2112 Japan Science and Technology Agency
- JP26116002 Ministry of Education, Culture, Sports, Science and Technology
- JP18H03984 Ministry of Education, Culture, Sports, Science and Technology
- JP21H04763 Ministry of Education, Culture, Sports, Science and Technology
- JP20H05925 Ministry of Education, Culture, Sports, Science and Technology
- 2019-25 Mitsubishi Foundation
- 2019 Uehara Memorial Foundation
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Affiliation(s)
- Hayato Ito
- School of Life Science and Technology, Tokyo Institute of Technology, S2-19, Nagatsuta 4259, Midori-ku, Yokohama, 226-8501, Japan
| | - Kodai Machida
- Graduate School of Engineering, University of Hyogo, Shosha, 2167, Himeji, Hyogo, 671-2280, Japan
| | - Mayuka Hasumi
- School of Life Science and Technology, Tokyo Institute of Technology, S2-19, Nagatsuta 4259, Midori-ku, Yokohama, 226-8501, Japan
| | - Morio Ueyama
- Department of Neurology, Faculty of Medicine, Kindai University, Ohonohigashi 377-2, Osaka-Sayama, 589-8511, Japan
| | - Yoshitaka Nagai
- Department of Neurology, Faculty of Medicine, Kindai University, Ohonohigashi 377-2, Osaka-Sayama, 589-8511, Japan
| | - Hiroaki Imataka
- Graduate School of Engineering, University of Hyogo, Shosha, 2167, Himeji, Hyogo, 671-2280, Japan
| | - Hideki Taguchi
- School of Life Science and Technology, Tokyo Institute of Technology, S2-19, Nagatsuta 4259, Midori-ku, Yokohama, 226-8501, Japan.
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, S2-19, Nagatsuta 4259, Midori-ku, Yokohama, 226-8501, Japan.
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3
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Ortega JA, Sasselli IR, Boccitto M, Fleming AC, Fortuna TR, Li Y, Sato K, Clemons TD, Mckenna ED, Nguyen TP, Anderson EN, Asin J, Ichida JK, Pandey UB, Wolin SL, Stupp SI, Kiskinis E. CLIP-Seq analysis enables the design of protective ribosomal RNA bait oligonucleotides against C9ORF72 ALS/FTD poly-GR pathophysiology. Sci Adv 2023; 9:eadf7997. [PMID: 37948524 PMCID: PMC10637751 DOI: 10.1126/sciadv.adf7997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 10/11/2023] [Indexed: 11/12/2023]
Abstract
Amyotrophic lateral sclerosis and frontotemporal dementia patients with a hexanucleotide repeat expansion in C9ORF72 (C9-HRE) accumulate poly-GR and poly-PR aggregates. The pathogenicity of these arginine-rich dipeptide repeats (R-DPRs) is thought to be driven by their propensity to bind low-complexity domains of multivalent proteins. However, the ability of R-DPRs to bind native RNA and the significance of this interaction remain unclear. Here, we used computational and experimental approaches to characterize the physicochemical properties of R-DPRs and their interaction with RNA. We find that poly-GR predominantly binds ribosomal RNA (rRNA) in cells and exhibits an interaction that is predicted to be energetically stronger than that for associated ribosomal proteins. Critically, modified rRNA "bait" oligonucleotides restore poly-GR-associated ribosomal deficits and ameliorate poly-GR toxicity in patient neurons and Drosophila models. Our work strengthens the hypothesis that ribosomal function is impaired by R-DPRs, highlights a role for direct rRNA binding in mediating ribosomal dysfunction, and presents a strategy for protecting against C9-HRE pathophysiological mechanisms.
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Affiliation(s)
- Juan A. Ortega
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Department of Pathology and Experimental Therapy, Institute of Neurosciences, University of Barcelona, Barcelona 08907, Spain
| | - Ivan R. Sasselli
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
- Center for Cooperative Research in Biomaterials (CIC biomaGUNE), Basque Research and Technology Alliance (BRTA), Donostia-San Sebastián 20014, Spain
- Centro de Fisica de Materiales (CFM), CSIC-UPV/EHU, 20018 San Sebastián, Spain
| | - Marco Boccitto
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Andrew C. Fleming
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Tyler R. Fortuna
- Department of Pediatrics, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Yichen Li
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Kohei Sato
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
| | - Tristan D. Clemons
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
| | - Elizabeth D. Mckenna
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Thao P. Nguyen
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Eric N. Anderson
- Department of Pediatrics, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Jesus Asin
- Department of Statistical Methods, School of Engineering, University of Zaragoza, Zaragoza 50018, Spain
| | - Justin K. Ichida
- Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
| | - Udai B. Pandey
- Department of Pediatrics, Children’s Hospital of Pittsburgh, University of Pittsburgh School of Medicine, Pittsburgh, PA 15224, USA
| | - Sandra L. Wolin
- RNA Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA
| | - Samuel I. Stupp
- Department of Chemistry, Northwestern University, Evanston, IL 60208, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
- Department of Biomedical Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208, USA
- Department of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Evangelos Kiskinis
- The Ken & Ruth Davee Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
- Simpson Querrey Institute for BioNanotechnology, Northwestern University, Chicago, IL 60611, USA
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
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4
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Wang S, Sun S. Translation dysregulation in neurodegenerative diseases: a focus on ALS. Mol Neurodegener 2023; 18:58. [PMID: 37626421 PMCID: PMC10464328 DOI: 10.1186/s13024-023-00642-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 07/21/2023] [Indexed: 08/27/2023] Open
Abstract
RNA translation is tightly controlled in eukaryotic cells to regulate gene expression and maintain proteome homeostasis. RNA binding proteins, translation factors, and cell signaling pathways all modulate the translation process. Defective translation is involved in multiple neurological diseases including amyotrophic lateral sclerosis (ALS). ALS is a progressive neurodegenerative disorder and poses a major public health challenge worldwide. Over the past few years, tremendous advances have been made in the understanding of the genetics and pathogenesis of ALS. Dysfunction of RNA metabolisms, including RNA translation, has been closely associated with ALS. Here, we first introduce the general mechanisms of translational regulation under physiological and stress conditions and review well-known examples of translation defects in neurodegenerative diseases. We then focus on ALS-linked genes and discuss the recent progress on how translation is affected by various mutant genes and the repeat expansion-mediated non-canonical translation in ALS.
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Affiliation(s)
- Shaopeng Wang
- Department of Physiology and Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA
| | - Shuying Sun
- Department of Physiology and Brain Science Institute, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- The Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, 21205, USA.
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5
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Tseng YJ, Malik I, Deng X, Krans A, Jansen-West K, Tank EM, Gomez NB, Sher R, Petrucelli L, Barmada SJ, Todd PK. Ribosomal quality control factors inhibit repeat-associated non-AUG translation from GC-rich repeats. bioRxiv 2023:2023.06.07.544135. [PMID: 37333274 PMCID: PMC10274811 DOI: 10.1101/2023.06.07.544135] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
A GGGGCC (G4C2) hexanucleotide repeat expansion in C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia (C9ALS/FTD), while a CGG trinucleotide repeat expansion in FMR1 leads to the neurodegenerative disorder Fragile X-associated tremor/ataxia syndrome (FXTAS). These GC-rich repeats form RNA secondary structures that support repeat-associated non-AUG (RAN) translation of toxic proteins that contribute to disease pathogenesis. Here we assessed whether these same repeats might trigger stalling and interfere with translational elongation. We find that depletion of ribosome-associated quality control (RQC) factors NEMF, LTN1, and ANKZF1 markedly boost RAN translation product accumulation from both G4C2 and CGG repeats while overexpression of these factors reduces RAN production in both reporter cell lines and C9ALS/FTD patient iPSC-derived neurons. We also detected partially made products from both G4C2 and CGG repeats whose abundance increased with RQC factor depletion. Repeat RNA sequence, rather than amino acid content, is central to the impact of RQC factor depletion on RAN translation - suggesting a role for RNA secondary structure in these processes. Together, these findings suggest that ribosomal stalling and RQC pathway activation during RAN translation elongation inhibits the generation of toxic RAN products. We propose augmenting RQC activity as a therapeutic strategy in GC-rich repeat expansion disorders.
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Affiliation(s)
- Yi-Ju Tseng
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Indranil Malik
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Xiexiong Deng
- Department of Molecular, Cellular and Developmental Biology, Howard Hughes Medical Institute, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
- Ann Arbor Veterans Administration Healthcare, Ann Arbor, MI, 48109, USA
| | - Karen Jansen-West
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | | | - Nicolas B. Gomez
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
- Medical Scientist Training Program, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Roger Sher
- Department of Neurobiology and Behavior & Center for Nervous System Disorders, Stony Brook University, Stony Brook, NY, 11794, USA
| | | | - Sami J. Barmada
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Peter K. Todd
- Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
- Ann Arbor Veterans Administration Healthcare, Ann Arbor, MI, 48109, USA
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6
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Boeynaems S, Ma XR, Yeong V, Ginell GM, Chen JH, Blum JA, Nakayama L, Sanyal A, Briner A, Haver DV, Pauwels J, Ekman A, Schmidt HB, Sundararajan K, Porta L, Lasker K, Larabell C, Hayashi MAF, Kundaje A, Impens F, Obermeyer A, Holehouse AS, Gitler AD. Aberrant phase separation is a common killing strategy of positively charged peptides in biology and human disease. bioRxiv 2023:2023.03.09.531820. [PMID: 36945394 PMCID: PMC10028949 DOI: 10.1101/2023.03.09.531820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Positively charged repeat peptides are emerging as key players in neurodegenerative diseases. These peptides can perturb diverse cellular pathways but a unifying framework for how such promiscuous toxicity arises has remained elusive. We used mass-spectrometry-based proteomics to define the protein targets of these neurotoxic peptides and found that they all share similar sequence features that drive their aberrant condensation with these positively charged peptides. We trained a machine learning algorithm to detect such sequence features and unexpectedly discovered that this mode of toxicity is not limited to human repeat expansion disorders but has evolved countless times across the tree of life in the form of cationic antimicrobial and venom peptides. We demonstrate that an excess in positive charge is necessary and sufficient for this killer activity, which we name 'polycation poisoning'. These findings reveal an ancient and conserved mechanism and inform ways to leverage its design rules for new generations of bioactive peptides.
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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 School of Medicine, Stanford, CA 94305, USA
| | - X. Rosa Ma
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Vivian Yeong
- Department of Chemical Engineering, Columbia University, New York, NY, 10027, USA
| | - Garrett M. Ginell
- 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
| | - Jian-Hua Chen
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
| | - Jacob A. Blum
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lisa Nakayama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Anushka Sanyal
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Adam Briner
- Clem Jones Centre for Ageing Dementia Research (CJCADR), Queensland Brain Institute (QBI), The University of Queensland, Brisbane, QLD 4072, Australia
| | - Delphi Van Haver
- VIB-UGent Center for Medical Biotechnology, 9000 Gent, Belgium
- VIB Proteomics Core, 9000 Gent, Belgium
- Department of Biochemistry, Ghent University, 9000 Gent, Belgium
| | - Jarne Pauwels
- VIB-UGent Center for Medical Biotechnology, 9000 Gent, Belgium
- VIB Proteomics Core, 9000 Gent, Belgium
- Department of Biochemistry, Ghent University, 9000 Gent, Belgium
| | - Axel Ekman
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
| | - H. Broder Schmidt
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Kousik Sundararajan
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Lucas Porta
- Department of Pharmacology, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo, Brazil
| | - Keren Lasker
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Carolyn Larabell
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
- Department of Anatomy, University of California, San Francisco, CA 94143, USA
| | - Mirian A. F. Hayashi
- Department of Pharmacology, Escola Paulista de Medicina (EPM), Universidade Federal de São Paulo (UNIFESP), Sao Paulo, Brazil
| | - Anshul Kundaje
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
- Department of Computer Science, Stanford University, Stanford, CA 94305, USA
| | - Francis Impens
- VIB-UGent Center for Medical Biotechnology, 9000 Gent, Belgium
- VIB Proteomics Core, 9000 Gent, Belgium
- Department of Biochemistry, Ghent University, 9000 Gent, Belgium
| | - Allie Obermeyer
- Department of Chemical Engineering, Columbia University, New York, NY, 10027, USA
| | - 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
| | - Aaron D. Gitler
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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7
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Kriachkov V, Ormsby AR, Kusnadi EP, McWilliam HE, Mintern JD, Amarasinghe SL, Ritchie ME, Furic L, Hatters DM. Arginine-rich C9ORF72 ALS proteins stall ribosomes in a manner distinct from a canonical ribosome-associated quality control substrate. J Biol Chem 2022; 299:102774. [PMID: 36481270 PMCID: PMC9830226 DOI: 10.1016/j.jbc.2022.102774] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 11/23/2022] [Accepted: 11/28/2022] [Indexed: 12/12/2022] Open
Abstract
Hexanucleotide expansion mutations in C9ORF72 are a frequent cause of amyotrophic lateral sclerosis. We previously reported that long arginine-rich dipeptide repeats (DPRs), mimicking abnormal proteins expressed from the hexanucleotide expansion, caused translation stalling when expressed in cell culture models. Whether this stalling provides a mechanism of pathogenicity remains to be determined. Here, we explored the molecular features of DPR-induced stalling and examined whether known mechanisms such as ribosome quality control (RQC) regulate translation elongation on sequences that encode arginine-rich DPRs. We demonstrate that arginine-rich DPRs lead to stalling in a length-dependent manner, with lengths longer than 40 repeats invoking severe translation arrest. Mutational screening of 40×Gly-Xxx DPRs shows that stalling is most pronounced when Xxx is a charged amino acid (Arg, Lys, Glu, or Asp). Through a genome-wide knockout screen, we find that genes regulating stalling on polyadenosine mRNA coding for poly-Lys, a canonical RQC substrate, act differently in the case of arginine-rich DPRs. Indeed, these findings point to a limited scope for natural regulatory responses to resolve the arginine-rich DPR stalls, even though the stalls may be sensed, as evidenced by an upregulation of RQC gene expression. These findings therefore implicate arginine-rich DPR-mediated stalled ribosomes as a source of stress and toxicity and may be a crucial component in pathomechanisms.
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Affiliation(s)
- Viacheslav Kriachkov
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Angelique R. Ormsby
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Eric P. Kusnadi
- Translational Prostate Cancer Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia
| | - Hamish E.G. McWilliam
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia,Department of Microbiology and Immunology, Peter Doherty Institute of Infection and Immunity, The University of Melbourne, Melbourne, Victoria, Australia
| | - Justine D. Mintern
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | | | - Matthew E. Ritchie
- Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Luc Furic
- Translational Prostate Cancer Research Laboratory, Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia,Sir Peter MacCallum Department of Oncology, University of Melbourne, Parkville, Victoria, Australia,Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute Cancer Program, Monash University, Clayton, Victoria, Australia
| | - Danny M. Hatters
- Department of Biochemistry and Pharmacology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia,For correspondence: Danny M. Hatters
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8
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Jiménez-Villegas J, Kirby J, Mata A, Cadenas S, Turner MR, Malaspina A, Shaw PJ, Cuadrado A, Rojo AI. Dipeptide Repeat Pathology in C9orf72-ALS Is Associated with Redox, Mitochondrial and NRF2 Pathway Imbalance. Antioxidants (Basel) 2022; 11:1897. [PMID: 36290620 PMCID: PMC9598689 DOI: 10.3390/antiox11101897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Revised: 09/19/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
The hexanucleotide expansion of the C9orf72 gene is found in 40% of familial amyotrophic lateral sclerosis (ALS) patients. This genetic alteration has been connected with impaired management of reactive oxygen species. In this study, we conducted targeted transcriptional profiling in leukocytes from C9orf72 patients and control subjects by examining the mRNA levels of 84 redox-related genes. The expression of ten redox genes was altered in samples from C9orf72 ALS patients compared to healthy controls. Considering that Nuclear factor erythroid 2-Related Factor 2 (NRF2) modulates the expression of a wide range of redox genes, we further investigated its status on an in vitro model of dipeptide repeat (DPR) toxicity. This model mimics the gain of function, toxic mechanisms attributed to C9orf72 pathology. We found that exposure to DPRs increased superoxide levels and reduced mitochondrial potential as well as cell survival. Importantly, cells overexpressing DPRs exhibited reduced protein levels of NRF2 and its target genes upon inhibition of the proteasome or its canonical repressor, the E3 ligase adapter KEAP1. However, NRF2 activation was sufficient to recover cell viability and redox homeostasis. This study identifies NRF2 as a putative target in precision medicine for the therapy of ALS patients harboring C9orf72 expansion repeats.
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Affiliation(s)
- José Jiménez-Villegas
- Department of Biochemistry, Medical College, Autonomous University of Madrid (UAM), 28029 Madrid, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM), 28029 Madrid, Spain
- Instituto de Investigación Sanitaria La Paz (IdiPaz), 28029 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28029 Madrid, Spain
| | - Janine Kirby
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Ana Mata
- Centro de Biología Molecular “Severo Ochoa” (CSIC/UAM), 28049 Madrid, Spain
- Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain
| | - Susana Cadenas
- Centro de Biología Molecular “Severo Ochoa” (CSIC/UAM), 28049 Madrid, Spain
- Instituto de Investigación Sanitaria Princesa (IIS-IP), 28006 Madrid, Spain
| | - Martin R. Turner
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK
| | - Andrea Malaspina
- Neuroscience and Trauma Centre, Blizard Institute, Barts and The London School of Medicine & Dentistry, Queen Mary University of London, London E1 2AT, UK
- Queen Square Motor Neuron Disease Centre, Neuromuscular Department, Institute of Neurology, University College London, London WC1N 3BG, UK
| | - Pamela J. Shaw
- Sheffield Institute for Translational Neuroscience, University of Sheffield, Sheffield S10 2HQ, UK
| | - Antonio Cuadrado
- Department of Biochemistry, Medical College, Autonomous University of Madrid (UAM), 28029 Madrid, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM), 28029 Madrid, Spain
- Instituto de Investigación Sanitaria La Paz (IdiPaz), 28029 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28029 Madrid, Spain
| | - Ana I. Rojo
- Department of Biochemistry, Medical College, Autonomous University of Madrid (UAM), 28029 Madrid, Spain
- Instituto de Investigaciones Biomédicas “Alberto Sols” (CSIC/UAM), 28029 Madrid, Spain
- Instituto de Investigación Sanitaria La Paz (IdiPaz), 28029 Madrid, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas (CIBERNED), 28029 Madrid, Spain
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9
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Loveland AB, Svidritskiy E, Susorov D, Lee S, Park A, Zvornicanin S, Demo G, Gao FB, Korostelev AA. Ribosome inhibition by C9ORF72-ALS/FTD-associated poly-PR and poly-GR proteins revealed by cryo-EM. Nat Commun 2022; 13:2776. [PMID: 35589706 PMCID: PMC9120013 DOI: 10.1038/s41467-022-30418-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 04/29/2022] [Indexed: 12/15/2022] Open
Abstract
Toxic dipeptide-repeat (DPR) proteins are produced from expanded G4C2 repeats in the C9ORF72 gene, the most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Two DPR proteins, poly-PR and poly-GR, repress cellular translation but the molecular mechanism remains unknown. Here we show that poly-PR and poly-GR of ≥20 repeats inhibit the ribosome's peptidyl-transferase activity at nanomolar concentrations, comparable to specific translation inhibitors. High-resolution cryogenic electron microscopy (cryo-EM) reveals that poly-PR and poly-GR block the polypeptide tunnel of the ribosome, extending into the peptidyl-transferase center (PTC). Consistent with these findings, the macrolide erythromycin, which binds in the tunnel, competes with poly-PR and restores peptidyl-transferase activity. Our results demonstrate that strong and specific binding of poly-PR and poly-GR in the ribosomal tunnel blocks translation, revealing the structural basis of their toxicity in C9ORF72-ALS/FTD.
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Affiliation(s)
- Anna B Loveland
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Egor Svidritskiy
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Denis Susorov
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Soojin Lee
- Department of Neurology, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Alexander Park
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Sarah Zvornicanin
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Gabriel Demo
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
- Central European Institute of Technology, Masaryk University, Kamenice 5, Brno, 625 00, Czech Republic
| | - Fen-Biao Gao
- Department of Neurology, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA.
| | - Andrei A Korostelev
- RNA Therapeutics Institute, UMass Chan Medical School, 368 Plantation Street, Worcester, MA, 01605, USA.
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10
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Benson BC, Shaw PJ, Azzouz M, Highley JR, Hautbergue GM. Proteinopathies as Hallmarks of Impaired Gene Expression, Proteostasis and Mitochondrial Function in Amyotrophic Lateral Sclerosis. Front Neurosci 2022; 15:783624. [PMID: 35002606 PMCID: PMC8733206 DOI: 10.3389/fnins.2021.783624] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Accepted: 11/26/2021] [Indexed: 01/15/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disease characterized by progressive degeneration of upper and lower motor neurons. As with the majority of neurodegenerative diseases, the pathological hallmarks of ALS involve proteinopathies which lead to the formation of various polyubiquitylated protein aggregates in neurons and glia. ALS is a highly heterogeneous disease, with both familial and sporadic forms arising from the convergence of multiple disease mechanisms, many of which remain elusive. There has been considerable research effort invested into exploring these disease mechanisms and in recent years dysregulation of RNA metabolism and mitochondrial function have emerged as of crucial importance to the onset and development of ALS proteinopathies. Widespread alterations of the RNA metabolism and post-translational processing of proteins lead to the disruption of multiple biological pathways. Abnormal mitochondrial structure, impaired ATP production, dysregulation of energy metabolism and calcium homeostasis as well as apoptosis have been implicated in the neurodegenerative process. Dysfunctional mitochondria further accumulate in ALS motor neurons and reflect a wider failure of cellular quality control systems, including mitophagy and other autophagic processes. Here, we review the evidence for RNA and mitochondrial dysfunction as some of the earliest critical pathophysiological events leading to the development of ALS proteinopathies, explore their relative pathological contributions and their points of convergence with other key disease mechanisms. This review will focus primarily on mutations in genes causing four major types of ALS (C9ORF72, SOD1, TARDBP/TDP-43, and FUS) and in protein homeostasis genes (SQSTM1, OPTN, VCP, and UBQLN2) as well as sporadic forms of the disease. Finally, we will look to the future of ALS research and how an improved understanding of central mechanisms underpinning proteinopathies might inform research directions and have implications for the development of novel therapeutic approaches.
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Affiliation(s)
- Bridget C Benson
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom
| | - Pamela J Shaw
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom
| | - Mimoun Azzouz
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.,Healthy Lifespan Institute (HELSI), University of Sheffield, Sheffield, United Kingdom
| | - J Robin Highley
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.,Healthy Lifespan Institute (HELSI), University of Sheffield, Sheffield, United Kingdom
| | - Guillaume M Hautbergue
- Department of Neuroscience, Sheffield Institute for Translational Neuroscience (SITraN), University of Sheffield, Sheffield, United Kingdom.,Neuroscience Institute, University of Sheffield, Sheffield, United Kingdom.,Healthy Lifespan Institute (HELSI), University of Sheffield, Sheffield, United Kingdom
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11
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Sui X, Radwan M, Cox D, Hatters DM. Probing Protein Solubility Patterns with Proteomics for Insight into Network Dynamics. Methods Mol Biol 2022; 2428:261-275. [PMID: 35171485 DOI: 10.1007/978-1-0716-1975-9_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Proteome solubility contains latent information on the nature of protein interaction networks in cells and changes in solubility can provide information on rewiring of networks. Here, we report a simple one-step ultracentrifugation method to separate the soluble and insoluble fraction of the proteome. The method involves quantitative proteomics and a bioinformatics strategy to analyze the changes that arise. Because protein solubility changes are also associated with protein misfolding and aggregation in neurodegenerative disease, we also include a protocol for isolating disease-associated protein aggregates with pulse shape analysis (PulSA) by flow cytometry as a complementary approach that can be used alongside the more general measure of solubility or as a stand-alone approach.
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Affiliation(s)
- Xiaojing Sui
- Department of Molecular Biosciences, Rice Institute for Biomedical Research, Northwestern University, Evanston, IL, USA
| | - Mona Radwan
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Dezerae Cox
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia
| | - Danny M Hatters
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, VIC, Australia.
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12
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Kanekura K, Hayamizu Y, Kuroda M. Order controls disordered droplets: structure-function relationships in C9orf72-derived poly(PR). Am J Physiol Cell Physiol 2021; 322:C197-C204. [PMID: 34910602 DOI: 10.1152/ajpcell.00372.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have been thought as two distinct neurodegenerative diseases. However, recent genetic screening and careful investigations found the genetic and pathological overlap among these disorders. Hexanucleotide expansions in intron 1 of C9orf72 are a leading cause of familial ALS and familial FTD. These expansions facilitate the repeat-associated non-ATG initiated translation (RAN translation), producing five dipeptide repeat proteins (DRPs), including Arg-rich poly(PR: Pro-Arg) and poly-(GR: Gly-Arg) peptides. Arg is a positively charged, highly polar amino acid that facilitates interactions with anionic molecules such as nucleic acids and acidic amino acids via electrostatic forces and aromatic amino acids via cation-pi interaction, suggesting that Arg-rich DRPs underlie the pathophysiology of ALS via Arg-mediated molecular interactions. Arg-rich DRPs have also been reported to induce neurodegeneration in cellular and animal models via multiple mechanisms; however, it remains unclear why the Arg-rich DRPs exhibit such diverse toxic properties, because not all Arg-rich peptides are toxic. In this mini-review, we discuss the current understanding of the pathophysiology of Arg-rich C9orf72 DRPs and introduce recent findings on the role of Arg distribution as a determinant of the toxicity and its contribution to the pathogenesis of ALS.
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Affiliation(s)
- Kohsuke Kanekura
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Tokyo, Japan
| | - Yuhei Hayamizu
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Masahiko Kuroda
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Tokyo, Japan
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13
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Thompson AG, Oeckl P, Feneberg E, Bowser R, Otto M, Fischer R, Kessler B, Turner MR. Advancing mechanistic understanding and biomarker development in amyotrophic lateral sclerosis. Expert Rev Proteomics 2021; 18:977-994. [PMID: 34758687 DOI: 10.1080/14789450.2021.2004890] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
INTRODUCTION Proteomic analysis has contributed significantly to the study of the neurodegenerative disease amyotrophic lateral sclerosis (ALS). It has helped to define the pathological change common to nearly all cases, namely intracellular aggregates of phosphorylated TDP-43, shifting the focus of pathogenesis in ALS toward RNA biology. Proteomics has also uniquely underpinned the delineation of disease mechanisms in model systems and has been central to recent advances in human ALS biomarker development. AREAS COVERED The contribution of proteomics to understanding the cellular pathological changes, disease mechanisms, and biomarker development in ALS are covered. EXPERT OPINION Proteomics has delivered unique insights into the pathogenesis of ALS and advanced the goal of objective measurements of disease activity to improve therapeutic trials. Further developments in sensitivity and quantification are expected, with application to the presymptomatic phase of human disease offering the hope of prevention strategies.
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Affiliation(s)
| | - Patrick Oeckl
- Department of Neurology, University of Ulm, Ulm, Germany.,German Center for Neurodegenerative Diseases (Dzne e.V.), Ulm, Germany
| | - Emily Feneberg
- Department of Neurology, Klinikum Rechts der Isar, Technical University Munich, Munich, Germany
| | - Robert Bowser
- Departments of Neurology and Translational Neuroscience, Barrow Neurological Institute, Phoenix, Arizona, USA
| | - Markus Otto
- Department of Neurology, University of Ulm, Ulm, Germany.,Department of Neurology, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Roman Fischer
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Benedikt Kessler
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Martin R Turner
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
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14
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Park J, Lee J, Kim JH, Lee J, Park H, Lim C. ZNF598 co-translationally titrates poly(GR) protein implicated in the pathogenesis of C9ORF72-associated ALS/FTD. Nucleic Acids Res 2021; 49:11294-11311. [PMID: 34551427 PMCID: PMC8565315 DOI: 10.1093/nar/gkab834] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 09/09/2021] [Indexed: 11/13/2022] Open
Abstract
C9ORF72-derived dipeptide repeat proteins have emerged as the pathogenic cause of neurodegeneration in amyotrophic lateral sclerosis and frontotemporal dementia (C9-ALS/FTD). However, the mechanisms underlying their expression are not fully understood. Here, we demonstrate that ZNF598, the rate-limiting factor for ribosome-associated quality control (RQC), co-translationally titrates the expression of C9ORF72-derived poly(GR) protein. A Drosophila genetic screen identified key RQC factors as potent modifiers of poly(GR)-induced neurodegeneration. ZNF598 overexpression in human neuroblastoma cells inhibited the nuclear accumulation of poly(GR) protein and decreased its cytotoxicity, whereas ZNF598 deletion had opposing effects. Poly(GR)-encoding sequences in the reporter RNAs caused translational stalling and generated ribosome-associated translation products, sharing molecular signatures with canonical RQC substrates. Furthermore, ZNF598 and listerin 1, the RQC E3 ubiquitin-protein ligase, promoted poly(GR) degradation via the ubiquitin-proteasome pathway. An ALS-relevant ZNF598R69C mutant displayed loss-of-function effects on poly(GR) expression, as well as on general RQC. Moreover, RQC function was impaired in C9-ALS patient-derived neurons, whereas lentiviral overexpression of ZNF598 lowered their poly(GR) expression and suppressed proapoptotic caspase-3 activation. Taken together, we propose that an adaptive nature of the RQC-relevant ZNF598 activity allows the co-translational surveillance to cope with the atypical expression of pathogenic poly(GR) protein, thereby acquiring a neuroprotective function in C9-ALS/FTD.
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Affiliation(s)
- Jumin Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Jongbo Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Ji-Hyung Kim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Jongbin Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Heeju Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
| | - Chunghun Lim
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan 44919, Republic of Korea
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15
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Chen C, Yamanaka Y, Ueda K, Li P, Miyagi T, Harada Y, Tezuka S, Narumi S, Sugimoto M, Kuroda M, Hayamizu Y, Kanekura K. Phase separation and toxicity of C9orf72 poly(PR) depends on alternate distribution of arginine. J Cell Biol 2021; 220:212626. [PMID: 34499080 PMCID: PMC8438627 DOI: 10.1083/jcb.202103160] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 08/05/2021] [Accepted: 08/19/2021] [Indexed: 12/15/2022] Open
Abstract
Arg (R)-rich dipeptide repeat proteins (DPRs; poly(PR): Pro-Arg and poly(GR): Gly-Arg), encoded by a hexanucleotide expansion in the C9ORF72 gene, induce neurodegeneration in amyotrophic lateral sclerosis (ALS). Although R-rich DPRs undergo liquid-liquid phase separation (LLPS), which affects multiple biological processes, mechanisms underlying LLPS of DPRs remain elusive. Here, using in silico, in vitro, and in cellulo methods, we determined that the distribution of charged Arg residues regulates the complex coacervation with anionic peptides and nucleic acids. Proteomic analyses revealed that alternate Arg distribution in poly(PR) facilitates entrapment of proteins with acidic motifs via LLPS. Transcription, translation, and diffusion of nucleolar nucleophosmin (NPM1) were impaired by poly(PR) with an alternate charge distribution but not by poly(PR) variants with a consecutive charge distribution. We propose that the pathogenicity of R-rich DPRs is mediated by disturbance of proteins through entrapment in the phase-separated droplets via sequence-controlled multivalent protein-protein interactions.
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Affiliation(s)
- Chen Chen
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Yoshiaki Yamanaka
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan
| | - Koji Ueda
- Cancer Proteomics Group, Cancer Precision Medicine Center, Japanese Foundation for Cancer Research, Tokyo, Japan
| | - Peiying Li
- Center for Biosystems Dynamics Research, RIKEN, Kanagawa, Japan
| | - Tamami Miyagi
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan
| | - Yuichiro Harada
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan
| | - Sayaka Tezuka
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Satoshi Narumi
- Department of Molecular Endocrinology, National Research Institute for Child Health and Development, Tokyo, Japan
| | - Masahiro Sugimoto
- Research and Development Center for Minimally Invasive Therapies, Tokyo Medical University, Tokyo, Japan
| | - Masahiko Kuroda
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan
| | - Yuhei Hayamizu
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo, Japan
| | - Kohsuke Kanekura
- Department of Molecular Pathology, Tokyo Medical University, Tokyo, Japan
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16
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Riemslagh FW, Verhagen RFM, van der Toorn EC, Smits DJ, Quint WH, van der Linde HC, van Ham TJ, Willemsen R. Reduction of oxidative stress suppresses poly-GR-mediated toxicity in zebrafish embryos. Dis Model Mech 2021; 14:272601. [PMID: 34693978 PMCID: PMC8649169 DOI: 10.1242/dmm.049092] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2021] [Accepted: 10/13/2021] [Indexed: 12/17/2022] Open
Abstract
The hexanucleotide (G4C2)-repeat expansion in the C9ORF72 gene is the most common pathogenic cause of frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS). This repeat expansion can be translated into dipeptide repeat proteins (DPRs), and distribution of the poly-GR DPR correlates with neurodegeneration in postmortem C9FTD/ALS brains. Here, we assessed poly-GR toxicity in zebrafish embryos, using an annexin A5-based fluorescent transgenic line (secA5) that allows for detection and quantification of apoptosis in vivo. Microinjection of RNA encoding poly-GR into fertilized oocytes evoked apoptosis in the brain and abnormal motor neuron morphology in the trunk of 1-4-days postfertilization embryos. Poly-GR can be specifically detected in protein homogenates from injected zebrafish and in the frontal cortexes of C9FTD/ALS cases. Poly-GR expression further elevated MitoSOX levels in zebrafish embryos, indicating oxidative stress. Inhibition of reactive oxygen species using Trolox showed full suppression of poly-GR toxicity. Our study indicates that poly-GR can exert its toxicity via oxidative stress. This zebrafish model can be used to find suppressors of poly-GR toxicity and identify its molecular targets underlying neurodegeneration observed in C9FTD/ALS. Summary: Toxicity of C9ALS/FTD poly-GR in zebrafish embryos is suppressed by Trolox, and poly-GR can be detected and quantified in zebrafish model protein homogenates, and in the frontal cortex of C9FTD/ALS cases.
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Affiliation(s)
- Fréderike W Riemslagh
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Rob F M Verhagen
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Esmay C van der Toorn
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Daphne J Smits
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Wim H Quint
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Herma C van der Linde
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Tjakko J van Ham
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus University Medical Center Rotterdam, 3000 CA, Rotterdam, The Netherlands
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17
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Suzuki H, Matsuoka M. Proline-arginine poly-dipeptide encoded by the C9orf72 repeat expansion inhibits adenosine deaminase acting on RNA. J Neurochem 2021; 158:753-765. [PMID: 34081786 DOI: 10.1111/jnc.15445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/25/2021] [Accepted: 05/31/2021] [Indexed: 12/20/2022]
Abstract
A GGGGCC hexanucleotide repeat expansion in the C9orf72 gene is linked to the pathogenesis of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9-ALS/FTD). Unconventional translation of the hexanucleotide repeat expansion generates five dipeptide repeat proteins (DPRs). The molecular mechanism underlying the DPR-linked neurotoxicity is under investigation. In this study, using cell-based models, we show that poly-proline-arginine DPR (poly-PR), the most neurotoxic DPR in vitro, binds to adenosine deaminase acting on RNA (ADAR)1p110 and ADAR2 and inhibits their RNA editing activity. We further show that poly-PR impairs cellular stress response that is mediated by ADAR1p110. These results together suggest that the poly-PR-mediated inhibition of the ADAR activity contributes to C9-ALS/FTD-linked neurotoxicity.
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Affiliation(s)
- Hiroaki Suzuki
- Department of Pharmacology, School of Medicine, Tokyo Medical University, Tokyo, Japan
| | - Masaaki Matsuoka
- Department of Pharmacology, School of Medicine, Tokyo Medical University, Tokyo, Japan
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18
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Frottin F, Pérez-Berlanga M, Hartl FU, Hipp MS. Multiple pathways of toxicity induced by C9orf72 dipeptide repeat aggregates and G 4C 2 RNA in a cellular model. eLife 2021; 10:62718. [PMID: 34161229 PMCID: PMC8221807 DOI: 10.7554/elife.62718] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 06/08/2021] [Indexed: 12/05/2022] Open
Abstract
The most frequent genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia is a G4C2 repeat expansion in the C9orf72 gene. This expansion gives rise to translation of aggregating dipeptide repeat (DPR) proteins, including poly-GA as the most abundant species. However, gain of toxic function effects have been attributed to either the DPRs or the pathological G4C2 RNA. Here, we analyzed in a cellular model the relative toxicity of DPRs and RNA. Cytoplasmic poly-GA aggregates, generated in the absence of G4C2 RNA, interfered with nucleocytoplasmic protein transport, but had little effect on cell viability. In contrast, nuclear poly-GA was more toxic, impairing nucleolar protein quality control and protein biosynthesis. Production of the G4C2 RNA strongly reduced viability independent of DPR translation and caused pronounced inhibition of nuclear mRNA export and protein biogenesis. Thus, while the toxic effects of G4C2 RNA predominate in the cellular model used, DPRs exert additive effects that may contribute to pathology.
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Affiliation(s)
- Frédéric Frottin
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), Gif-sur-Yvette, France
| | - Manuela Pérez-Berlanga
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Quantitative Biomedicine, University of Zurich, Zurich, Switzerland
| | - F Ulrich Hartl
- Max Planck Institute of Biochemistry, Martinsried, Germany
| | - Mark S Hipp
- Max Planck Institute of Biochemistry, Martinsried, Germany.,Department of Biomedical Sciences of Cells and Systems, University Medical Center Groningen, University of Groningen, Groningen, Netherlands.,School of Medicine and Health Sciences, Carl von Ossietzky University Oldenburg, Oldenburg, Germany
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19
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Abstract
Amyotrophic Lateral Sclerosis (ALS) is a complex neurodegenerative disease caused by degeneration of motor neurons (MNs). ALS pathogenic features include accumulation of misfolded proteins, glutamate excitotoxicity, mitochondrial dysfunction at distal axon terminals, and neuronal cytoskeleton changes. Synergies between loss of C9orf72 functions and gain of function by toxic effects of repeat expansions also contribute to C9orf72-mediated pathogenesis. However, the impact of haploinsufficiency of C9orf72 on neurons and in synaptic functions requires further examination. As the motor neurons degenerate, the disease symptoms will lead to neurotransmission deficiencies in the brain, spinal cord, and neuromuscular junction. Altered neuronal excitability, synaptic morphological changes, and C9orf72 protein and DPR localization at the synapses, suggest a potential involvement of C9orf72 at synapses. In this review article, we provide a conceptual framework for assessing the putative involvement of C9orf72 as a synaptopathy, and we explore the underlying and common disease mechanisms with other neurodegenerative diseases. Finally, we reflect on the major challenges of understanding C9orf72-ALS as a synaptopathy focusing on integrating mitochondrial and neuronal cytoskeleton degeneration as biomarkers and potential targets to treat ALS neurodegeneration.
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Affiliation(s)
- Agnes L Nishimura
- Department of Basic and Clinical Neuroscience, UK Dementia Research Institute, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom
| | - Natalia Arias
- Department of Basic and Clinical Neuroscience, UK Dementia Research Institute, Maurice Wohl Clinical Neuroscience Institute, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, United Kingdom.,INEUROPA, Instituto de Neurociencias del Principado de Asturias, Oviedo, Spain
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20
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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] [What about the content of this article? (0)] [Affiliation(s)] [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.
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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
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21
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Leskelä S, Huber N, Hoffmann D, Rostalski H, Remes AM, Takalo M, Hiltunen M, Haapasalo A. Expression of C9orf72 hexanucleotide repeat expansion leads to formation of RNA foci and dipeptide repeat proteins but does not influence autophagy or proteasomal function in neuronal cells. Biochim Biophys Acta Mol Cell Res 2021; 1868:119021. [PMID: 33775797 DOI: 10.1016/j.bbamcr.2021.119021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 03/06/2021] [Accepted: 03/22/2021] [Indexed: 12/22/2022]
Abstract
C9orf72 hexanucleotide repeat expansion (HRE) is the major genetic cause underpinning frontotemporal lobar degeneration (FLTD) and amyotrophic lateral sclerosis (ALS). C9orf72 HRE-associated pathogenesis involves both loss-of-function, through reduced C9orf72 levels, and gain-of-function mechanisms, including formation of RNA foci and generation of dipeptide repeat (DPR) proteins. In addition, dysfunctional protein degradation pathways, i.e. autophagy and ubiquitin-proteasome system (UPS), are suggested. Our aim was to study the gain-of-function mechanisms in the context of the function of protein degradation pathways as well as the regulation of the DPR proteins through these pathways. To this end, we expressed the pathological HRE in neuronal N2a cells and mouse primary cortical neurons. Protein degradation pathways were modulated to induce or block autophagy or to inhibit UPS. In addition, proteasomal activity was assessed. The C9orf72 HRE-expressing N2a cells and neurons were confirmed to produce RNA foci and DPR proteins, predominantly the Poly-GP proteins. However, the presence of these pathological hallmarks did not result in alterations in autophagy or proteasomal activity in either of the studied cell types. In N2a cells, Poly-GP proteins appeared in soluble forms and Lactacystin-mediated UPS inhibition increased their levels, indicating proteasomal regulation. Similar effects were not observed in cortical neurons, where the Poly-GP proteins formed also higher molecular weight forms. These results suggest a cell type-specific morphology and regulation of the DPR proteins. Further studies in other model systems may shed additional light onto the effects of the C9orf72 HRE on cellular protein degradation pathways and the regulation of the DPR protein levels.
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Radwan M, Lilley JD, Ang CS, Reid GE, Hatters DM. Immiscible inclusion bodies formed by polyglutamine and poly(glycine-alanine) are enriched with distinct proteomes but converge in proteins that are risk factors for disease and involved in protein degradation. PLoS One 2020; 15:e0233247. [PMID: 32857759 DOI: 10.1371/journal.pone.0233247] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/13/2020] [Indexed: 12/12/2022] Open
Abstract
Poly(glycine-alanine) (polyGA) is one of the polydipeptides expressed in Frontotemporal Dementia and/or Amyotrophic Lateral Sclerosis 1 caused by C9ORF72 mutations and accumulates as inclusion bodies in the brain of patients. Superficially these inclusions are similar to those formed by polyglutamine (polyQ)-expanded Huntingtin exon 1 (Httex1) in Huntington’s disease. Both have been reported to form an amyloid-like structure suggesting they might aggregate via similar mechanisms and therefore recruit the same repertoire of endogenous proteins. When co-expressed in the same cell, polyGA101 and Httex1(Q97) inclusions adopted immiscible phases suggesting different endogenous proteins would be enriched. Proteomic analyses identified 822 proteins in the inclusions. Only 7 were specific to polyGA and 4 specific to Httex1(Q97). Quantitation demonstrated distinct enrichment patterns for the proteins not specific to each inclusion type (up to ~8-fold normalized to total mass). The proteasome, microtubules, TriC chaperones, and translational machinery were enriched in polyGA aggregates, whereas Dnaj chaperones, nuclear envelope and RNA splicing proteins were enriched in Httex1(Q97) aggregates. Both structures revealed a collection of folding and degradation machinery including proteins in the Httex1(Q97) aggregates that are risk factors for other neurodegenerative diseases involving protein aggregation when mutated, which suggests a convergence point in the pathomechanisms of these diseases.
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Ormsby AR, Cox D, Daly J, Priest D, Hinde E, Hatters DM. Nascent mutant Huntingtin exon 1 chains do not stall on ribosomes during translation but aggregates do recruit machinery involved in ribosome quality control and RNA. PLoS One 2020; 15:e0233583. [PMID: 32735619 PMCID: PMC7394408 DOI: 10.1371/journal.pone.0233583] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022] Open
Abstract
Mutations that cause Huntington’s Disease involve a polyglutamine (polyQ) sequence expansion beyond 35 repeats in exon 1 of Huntingtin. Intracellular inclusion bodies of mutant Huntingtin protein are a key feature of Huntington’s disease brain pathology. We previously showed that in cell culture the formation of inclusions involved the assembly of disordered structures of mHtt exon 1 fragments (Httex1) and they were enriched with translational machinery when first formed. We hypothesized that nascent mutant Httex1 chains co-aggregate during translation by phase separation into liquid-like disordered aggregates and then convert to more rigid, amyloid structures. Here we further examined the mechanisms of inclusion assembly in a human epithelial kidney (AD293) cell culture model. We found mHttex1 did not appear to stall translation of its own nascent chain, or at best was marginal. We also found the inclusions appeared to recruit low levels of RNA but there was no difference in enrichment between early formed and mature inclusions. Proteins involved in translation or ribosome quality control were co-recruited to the inclusions (Ltn1 Rack1) compared to a protein not anticipated to be involved (NACAD), but there was no major specificity of enrichment in the early formed inclusions compared to mature inclusions. Furthermore, we observed co-aggregation with other proteins previously identified in inclusions, including Upf1 and chaperone-like proteins Sgta and Hspb1, which also suppressed aggregation at high co-expression levels. The newly formed inclusions also contained immobile mHttex1 molecules which points to the disordered aggregates being mechanically rigid prior to amyloid formation. Collectively our findings show little evidence that inclusion assembly arises by a discrete clustering of stalled nascent chains and associated quality control machinery. Instead, the machinery appear to be recruited continuously, or secondarily, to the nucleation of inclusion formation.
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Affiliation(s)
- Angelique R. Ormsby
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
| | - Dezerae Cox
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
| | - James Daly
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
| | - David Priest
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
| | - Elizabeth Hinde
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
| | - Danny M. Hatters
- Department of Biochemistry and Molecular Biology; and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, VIC, Australia
- * E-mail:
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