1
|
Chen S, Heendeniya SN, Le BT, Rahimizadeh K, Rabiee N, Zahra QUA, Veedu RN. Splice-Modulating Antisense Oligonucleotides as Therapeutics for Inherited Metabolic Diseases. BioDrugs 2024; 38:177-203. [PMID: 38252341 PMCID: PMC10912209 DOI: 10.1007/s40259-024-00644-7] [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] [Accepted: 01/03/2024] [Indexed: 01/23/2024]
Abstract
The last decade (2013-2023) has seen unprecedented successes in the clinical translation of therapeutic antisense oligonucleotides (ASOs). Eight such molecules have been granted marketing approval by the United States Food and Drug Administration (US FDA) during the decade, after the first ASO drug, fomivirsen, was approved much earlier, in 1998. Splice-modulating ASOs have also been developed for the therapy of inborn errors of metabolism (IEMs), due to their ability to redirect aberrant splicing caused by mutations, thus recovering the expression of normal transcripts, and correcting the deficiency of functional proteins. The feasibility of treating IEM patients with splice-switching ASOs has been supported by FDA permission (2018) of the first "N-of-1" study of milasen, an investigational ASO drug for Batten disease. Although for IEM, owing to the rarity of individual disease and/or pathogenic mutation, only a low number of patients may be treated by ASOs that specifically suppress the aberrant splicing pattern of mutant precursor mRNA (pre-mRNA), splice-switching ASOs represent superior individualized molecular therapeutics for IEM. In this work, we first summarize the ASO technology with respect to its mechanisms of action, chemical modifications of nucleotides, and rational design of modified oligonucleotides; following that, we precisely provide a review of the current understanding of developing splice-modulating ASO-based therapeutics for IEM. In the concluding section, we suggest potential ways to improve and/or optimize the development of ASOs targeting IEM.
Collapse
Affiliation(s)
- Suxiang Chen
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
| | - Saumya Nishanga Heendeniya
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
| | - Bao T Le
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
- ProGenis Pharmaceuticals Pty Ltd, Bentley, WA, 6102, Australia
| | - Kamal Rahimizadeh
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
| | - Navid Rabiee
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
| | - Qurat Ul Ain Zahra
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia
| | - Rakesh N Veedu
- Centre for Molecular Medicine and Innovative Therapeutics, Health Futures Institute, Murdoch University, Murdoch, WA, 6150, Australia.
- Precision Nucleic Acid Therapeutics, Perron Institute for Neurological and Translational Science, Nedlands, WA, 6009, Australia.
- ProGenis Pharmaceuticals Pty Ltd, Bentley, WA, 6102, Australia.
| |
Collapse
|
2
|
Kuijper EC, Bergsma AJ, Pijnappel WP, Aartsma‐Rus A. Opportunities and challenges for antisense oligonucleotide therapies. J Inherit Metab Dis 2021; 44:72-87. [PMID: 32391605 PMCID: PMC7891411 DOI: 10.1002/jimd.12251] [Citation(s) in RCA: 73] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Revised: 04/23/2020] [Accepted: 05/08/2020] [Indexed: 12/12/2022]
Abstract
Antisense oligonucleotide (AON) therapies involve short strands of modified nucleotides that target RNA in a sequence-specific manner, inducing targeted protein knockdown or restoration. Currently, 10 AON therapies have been approved in the United States and Europe. Nucleotides are chemically modified to protect AONs from degradation, enhance bioavailability and increase RNA affinity. Whereas single stranded AONs can efficiently be delivered systemically, delivery of double stranded AONs requires capsulation in lipid nanoparticles or binding to a conjugate as the uptake enhancing backbone is hidden in this conformation. With improved chemistry, delivery vehicles and conjugates, doses can be lowered, thereby reducing the risk and occurrence of side effects. AONs can be used to knockdown or restore levels of protein. Knockdown can be achieved by single stranded or double stranded AONs binding the RNA transcript and activating RNaseH-mediated and RISC-mediated degradation respectively. Transcript binding by AONs can also prevent translation, hence reducing protein levels. For protein restoration, single stranded AONs are used to modulate pre-mRNA splicing and either include or skip an exon to restore protein production. Intervening at a genetic level, AONs provide therapeutic options for inherited metabolic diseases as well. This review provides an overview of the different AON approaches, with a focus on AONs developed for inborn errors of metabolism.
Collapse
Affiliation(s)
- Elsa C. Kuijper
- Department of Human GeneticsLeiden University Medical CenterLeidenThe Netherlands
| | - Atze J. Bergsma
- Department of PediatricsCenter for Lysosomal and Metabolic Diseases, Erasmus Medical CenterRotterdamThe Netherlands
- Department of Clinical GeneticsCenter for Lysosomal and Metabolic Diseases, Erasmus Medical CenterRotterdamThe Netherlands
| | - W.W.M. Pim Pijnappel
- Department of PediatricsCenter for Lysosomal and Metabolic Diseases, Erasmus Medical CenterRotterdamThe Netherlands
- Department of Clinical GeneticsCenter for Lysosomal and Metabolic Diseases, Erasmus Medical CenterRotterdamThe Netherlands
| | | |
Collapse
|
3
|
Montes M, Sanford BL, Comiskey DF, Chandler DS. RNA Splicing and Disease: Animal Models to Therapies. Trends Genet 2019; 35:68-87. [PMID: 30466729 PMCID: PMC6339821 DOI: 10.1016/j.tig.2018.10.002] [Citation(s) in RCA: 121] [Impact Index Per Article: 24.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/01/2018] [Accepted: 10/16/2018] [Indexed: 02/07/2023]
Abstract
Alternative splicing of pre-mRNA increases genetic diversity, and recent studies estimate that most human multiexon genes are alternatively spliced. If this process is not highly regulated and accurate, it leads to mis-splicing events, which may result in proteins with altered function. A growing body of work has implicated mis-splicing events in a range of diseases, including cancer, neurodegenerative diseases, and muscular dystrophies. Understanding the mechanisms that cause aberrant splicing events and how this leads to disease is vital for designing effective therapeutic strategies. In this review, we focus on advances in therapies targeting splicing, and highlight the animal models developed to recapitulate disease phenotypes as a model for testing these therapies.
Collapse
Affiliation(s)
- Matías Montes
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Brianne L Sanford
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Daniel F Comiskey
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA
| | - Dawn S Chandler
- Molecular, Cellular, and Developmental Biology Graduate Program and The Center for RNA Biology, The Ohio State University, Columbus, OH, USA; Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, Columbus, OH, USA; Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH, USA.
| |
Collapse
|
4
|
Rawcliffe DFR, Österman L, Nordin A, Holmberg M. PTBP1 acts as a dominant repressor of the aberrant tissue-specific splicing of ISCU in hereditary myopathy with lactic acidosis. Mol Genet Genomic Med 2018; 6:887-897. [PMID: 30209894 PMCID: PMC6305642 DOI: 10.1002/mgg3.413] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Revised: 03/23/2018] [Accepted: 04/17/2018] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Hereditary myopathy with lactic acidosis (HML) is an autosomal recessive disease caused by an intron mutation in the iron-sulfur cluster assembly (ISCU) gene. The mutation results in aberrant splicing, where part of the intron is retained in the final mRNA transcript, giving rise to a truncated nonfunctional ISCU protein. Using an ISCU mini-gene system, we have previously shown that PTBP1 can act as a repressor of the mis-splicing of ISCU, where overexpression of PTBP1 resulted in a decrease of the incorrect splicing. In this study, we wanted to, in more detail, analyze the role of PTBP1 in the regulation of endogenous ISCU mis-splicing. METHODS Overexpression and knockdown of PTBP1 was performed in myoblasts from two HML patients and a healthy control. Quantification of ISCU mis-splicing was done by qRTPCR. Biotinylated ISCU RNA, representing wildtype and mutant intron sequence, was used in a pull-down assay with nuclear extracts from myoblasts. Levels of PTBP1 in human cell lines and mice tissues were analyzed by qRTPCR and western blot. RESULTS PTBP1 overexpression in HML patient myoblasts resulted in a substantial decrease of ISCU mis-splicing while knockdown of PTBP1 resulted in a drastic increase. The effect could be observed in both patient and control myoblasts. We could also show that PTBP1 interacts with both the mutant and wild-type ISCU intron sequence, but with a higher affinity to the mutant sequence. Furthermore, low levels of PTBP1 among examined mouse tissues correlated with high levels of incorrect splicing of ISCU. CONCLUSION Our results show that PTBP1 acts as a dominant repressor of ISCU mis-splicing. We also show an inverse correlation between the levels of PTBP1 and ISCU mis-splicing, suggesting that the high level of mis-splicing in the skeletal muscle is primarily due to the low levels of PTBP1.
Collapse
Affiliation(s)
- Denise F. R. Rawcliffe
- Unit for Medical and Clinical GeneticsDepartment of Medical BiosciencesUmeå UniversityUmeåSweden
| | - Lennart Österman
- Unit for Medical and Clinical GeneticsDepartment of Medical BiosciencesUmeå UniversityUmeåSweden
| | - Angelica Nordin
- Unit for Medical and Clinical GeneticsDepartment of Medical BiosciencesUmeå UniversityUmeåSweden
| | - Monica Holmberg
- Unit for Medical and Clinical GeneticsDepartment of Medical BiosciencesUmeå UniversityUmeåSweden
| |
Collapse
|
5
|
Palhais B, Dembic M, Sabaratnam R, Nielsen KS, Doktor TK, Bruun GH, Andresen BS. The prevalent deep intronic c. 639+919 G>A GLA mutation causes pseudoexon activation and Fabry disease by abolishing the binding of hnRNPA1 and hnRNP A2/B1 to a splicing silencer. Mol Genet Metab 2016; 119:258-269. [PMID: 27595546 DOI: 10.1016/j.ymgme.2016.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 08/25/2016] [Accepted: 08/26/2016] [Indexed: 11/21/2022]
Abstract
Fabry disease is an X-linked recessive inborn disorder of the glycosphingolipid metabolism, caused by total or partial deficiency of the lysosomal α-galactosidase A enzyme due to mutations in the GLA gene. The prevalent c.639+919 G>A mutation in GLA leads to pathogenic insertion of a 57bp pseudoexon sequence from intron 4, which is responsible for the cardiac variant phenotype. In this study we investigate the splicing regulatory mechanism leading to GLA pseudoexon activation. Splicing analysis of GLA minigenes revealed that pseudoexon activation is influenced by cell-type. We demonstrate that the wild-type sequence harbors an hnRNP A1 and hnRNP A2/B1-binding exonic splicing silencer (ESS) overlapping the 5'splice site (5'ss) that prevents pseudoexon inclusion. The c.639+919 G>A mutation disrupts this ESS allowing U1 snRNP recognition of the 5'ss. We show that the wild-type GLA 5'ss motif with the ESS is also able to inhibit inclusion of an unrelated pseudoexon in the FGB gene, and that also in the FGB context inactivation of the ESS by the c.639+919 G>A mutation causes pseudoexon activation, underscoring the universal nature of the ESS. Finally, we demonstrate that splice switching oligonucleotide (SSO) mediated blocking of the pseudoexon 3'ss and 5'ss effectively restores normal GLA splicing. This indicates that SSO based splicing correction may be a therapeutic alternative in the treatment of Fabry disease.
Collapse
Affiliation(s)
- Bruno Palhais
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Maja Dembic
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Rugivan Sabaratnam
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Kira S Nielsen
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Thomas Koed Doktor
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Gitte Hoffmann Bruun
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark
| | - Brage Storstein Andresen
- Department of Biochemistry and Molecular Biology, the Villum Center for Bioanalytical Sciences, University of Southern Denmark, Odense M, Denmark.
| |
Collapse
|
6
|
Lundin KE, Gissberg O, Smith CE. Oligonucleotide Therapies: The Past and the Present. Hum Gene Ther 2015; 26:475-85. [PMID: 26160334 PMCID: PMC4554547 DOI: 10.1089/hum.2015.070] [Citation(s) in RCA: 193] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 07/04/2015] [Indexed: 12/19/2022] Open
Abstract
In this review we address the development of oligonucleotide (ON) medicines from a historical perspective by listing the landmark discoveries in this field. The various biological processes that have been targeted and the corresponding ON interventions found in the literature are discussed together with brief updates on some of the more recent developments. Most ON therapies act through antisense mechanisms and are directed against various RNA species, as exemplified by gapmers, steric block ONs, antagomirs, small interfering RNAs (siRNAs), micro-RNA mimics, and splice switching ONs. However, ONs binding to Toll-like receptors and those forming aptamers have completely different modes of action. Similar to other novel medicines, the path to success has been lined with numerous failures, where different therapeutic ONs did not stand the test of time. Since the first ON drug was approved for clinical use in 1998, the therapeutic landscape has changed considerably, but many challenges remain until the expectations for this new form of medicine are met. However, there is room for cautious optimism.
Collapse
Affiliation(s)
- Karin E. Lundin
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - Olof Gissberg
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| | - C.I. Edvard Smith
- Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden
| |
Collapse
|
7
|
Pérez B, Vilageliu L, Grinberg D, Desviat LR. Antisense mediated splicing modulation for inherited metabolic diseases: challenges for delivery. Nucleic Acid Ther 2014; 24:48-56. [PMID: 24506780 DOI: 10.1089/nat.2013.0453] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the past few years, research in targeted mutation therapies has experienced significant advances, especially in the field of rare diseases. In particular, the efficacy of antisense therapy for suppression of normal, pathogenic, or cryptic splice sites has been demonstrated in cellular and animal models and has already reached the clinical trials phase for Duchenne muscular dystrophy. In different inherited metabolic diseases, splice switching oligonucleotides (SSOs) have been used with success in patients' cells to force pseudoexon skipping or to block cryptic splice sites, in both cases recovering normal transcript and protein and correcting the enzyme deficiency. However, future in vivo studies require individual approaches for delivery depending on the gene defect involved, given the different patterns of tissue and organ expression. Herein we review the state of the art of antisense therapy targeting RNA splicing in metabolic diseases, grouped according to their expression patterns-multisystemic, hepatic, or in central nervous system (CNS)-and summarize the recent progress achieved in the field of in vivo delivery of oligonucleotides to each organ or system. Successful body-wide distribution of SSOs and preferential distribution in the liver after systemic administration have been reported in murine models for different diseases, while for CNS limited data are available, although promising results with intratechal injections have been achieved.
Collapse
Affiliation(s)
- Belen Pérez
- 1 Centro de Biología Molecular Severo Ochoa, UAM-CSIC, Universidad Autónoma de Madrid , Madrid, Spain. Centro de Investigación Biomédica en Red de Enfermedades Raras, Madrid, Spain
| | | | | | | |
Collapse
|
8
|
Maio N, Rouault TA. Iron-sulfur cluster biogenesis in mammalian cells: New insights into the molecular mechanisms of cluster delivery. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1853:1493-512. [PMID: 25245479 DOI: 10.1016/j.bbamcr.2014.09.009] [Citation(s) in RCA: 155] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 09/07/2014] [Indexed: 01/19/2023]
Abstract
Iron-sulfur (Fe-S) clusters are ancient, ubiquitous cofactors composed of iron and inorganic sulfur. The combination of the chemical reactivity of iron and sulfur, together with many variations of cluster composition, oxidation states and protein environments, enables Fe-S clusters to participate in numerous biological processes. Fe-S clusters are essential to redox catalysis in nitrogen fixation, mitochondrial respiration and photosynthesis, to regulatory sensing in key metabolic pathways (i.e. cellular iron homeostasis and oxidative stress response), and to the replication and maintenance of the nuclear genome. Fe-S cluster biogenesis is a multistep process that involves a complex sequence of catalyzed protein-protein interactions and coupled conformational changes between the components of several dedicated multimeric complexes. Intensive studies of the assembly process have clarified key points in the biogenesis of Fe-S proteins. However several critical questions still remain, such as: what is the role of frataxin? Why do some defects of Fe-S cluster biogenesis cause mitochondrial iron overload? How are specific Fe-S recipient proteins recognized in the process of Fe-S transfer? This review focuses on the basic steps of Fe-S cluster biogenesis, drawing attention to recent advances achieved on the identification of molecular features that guide selection of specific subsets of nascent Fe-S recipients by the cochaperone HSC20. Additionally, it outlines the distinctive phenotypes of human diseases due to mutations in the components of the basic pathway. This article is part of a Special Issue entitled: Fe/S proteins: Analysis, structure, function, biogenesis and diseases.
Collapse
Affiliation(s)
- Nunziata Maio
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA
| | - Tracey A Rouault
- Molecular Medicine Program, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 9000 Rockville Pike, 20892 Bethesda, MD, USA.
| |
Collapse
|
9
|
Havens MA, Duelli DM, Hastings ML. Targeting RNA splicing for disease therapy. WILEY INTERDISCIPLINARY REVIEWS. RNA 2013; 4:247-66. [PMID: 23512601 PMCID: PMC3631270 DOI: 10.1002/wrna.1158] [Citation(s) in RCA: 128] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Splicing of pre-messenger RNA into mature messenger RNA is an essential step for the expression of most genes in higher eukaryotes. Defects in this process typically affect cellular function and can have pathological consequences. Many human genetic diseases are caused by mutations that cause splicing defects. Furthermore, a number of diseases are associated with splicing defects that are not attributed to overt mutations. Targeting splicing directly to correct disease-associated aberrant splicing is a logical approach to therapy. Splicing is a favorable intervention point for disease therapeutics, because it is an early step in gene expression and does not alter the genome. Significant advances have been made in the development of approaches to manipulate splicing for therapy. Splicing can be manipulated with a number of tools including antisense oligonucleotides, modified small nuclear RNAs (snRNAs), trans-splicing, and small molecule compounds, all of which have been used to increase specific alternatively spliced isoforms or to correct aberrant gene expression resulting from gene mutations that alter splicing. Here we describe clinically relevant splicing defects in disease states, the current tools used to target and alter splicing, specific mutations and diseases that are being targeted using splice-modulating approaches, and emerging therapeutics.
Collapse
Affiliation(s)
- Mallory A. Havens
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science. North Chicago, IL, 60064, USA. No conflicts of interest
| | - Dominik M. Duelli
- Department of Cellular and Molecular Pharmacology, Chicago Medical School, Rosalind Franklin University of Medicine and Science, North Chicago, IL, 60064, USA. No conflicts of interest
| | - Michelle L. Hastings
- Department of Cell Biology and Anatomy, Chicago Medical School, Rosalind Franklin University of Medicine and Science. North Chicago, IL, 60064, USA, Phone: 847-578-8517 Fax: 847-578-3253. No conflicts of interest
| |
Collapse
|