1
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Fare CM, Rothstein JD. Nuclear pore dysfunction and disease: a complex opportunity. Nucleus 2024; 15:2314297. [PMID: 38383349 PMCID: PMC10883112 DOI: 10.1080/19491034.2024.2314297] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 01/30/2024] [Indexed: 02/23/2024] Open
Abstract
The separation of genetic material from bulk cytoplasm has enabled the evolution of increasingly complex organisms, allowing for the development of sophisticated forms of life. However, this complexity has created new categories of dysfunction, including those related to the movement of material between cellular compartments. In eukaryotic cells, nucleocytoplasmic trafficking is a fundamental biological process, and cumulative disruptions to nuclear integrity and nucleocytoplasmic transport are detrimental to cell survival. This is particularly true in post-mitotic neurons, where nuclear pore injury and errors to nucleocytoplasmic trafficking are strongly associated with neurodegenerative disease. In this review, we summarize the current understanding of nuclear pore biology in physiological and pathological contexts and discuss potential therapeutic approaches for addressing nuclear pore injury and dysfunctional nucleocytoplasmic transport.
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Affiliation(s)
- Charlotte M Fare
- Department of Neurology and Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Jeffrey D Rothstein
- Department of Neurology and Brain Science Institute, Johns Hopkins University, Baltimore, MD, USA
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2
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Ketabforoush A, Faghihi F, Azedi F, Ariaei A, Habibi MA, Khalili M, Ashtiani BH, Joghataei MT, Arnold WD. Sodium Phenylbutyrate and Tauroursodeoxycholic Acid: A Story of Hope Turned to Disappointment in Amyotrophic Lateral Sclerosis Treatment. Clin Drug Investig 2024:10.1007/s40261-024-01371-1. [PMID: 38909349 DOI: 10.1007/s40261-024-01371-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/26/2024] [Indexed: 06/24/2024]
Abstract
The absence of a definitive cure for amyotrophic lateral sclerosis (ALS) emphasizes the crucial need to explore new and improved treatment approaches for this fatal, progressive, and disabling neurodegenerative disorder. As at the end of 2023, five treatments - riluzole, edaravone, dextromethorphan hydrobromide + quinidine sulfate (DHQ), tofersen, and sodium phenylbutyrate-tauroursodeoxycholic acid (PB-TUDCA) - were FDA approved for the treatment of patients with ALS. Among them PB-TUDCA has been shown to impact DNA processing impairments, mitochondria dysfunction, endoplasmic reticulum stress, oxidative stress, and pathologic folded protein agglomeration defects, which have been associated with ALS pathophysiology. The Phase 2 CENTAUR trial demonstrated significant impact of PB-TUDCA on the ALS Functional Rating Scale-Revised (ALSFRS-R) risk of death, hospitalization, and the need for tracheostomy or permanent assisted ventilation in patients with ALS based on post hoc analyses. More recently, contrasting with the CENTAUR trial results, results from the Phase 3 PHOENIX trial (NCT05021536) showed no change in ALSFRS-R total score at 48 weeks. Consequently, the sponsor company initiated the process with the USÂ FDA and Health Canada to voluntarily withdraw the marketing authorizations for PB-TUDCA. In the present article, we review ALS pathophysiology, with a focus on PB-TUDCA's proposed mechanisms of action and recent clinical trial results and discuss the implications of conflicting trial data for ALS and other neurological disorders.
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Affiliation(s)
- Arsh Ketabforoush
- NextGen Precision Health, University of Missouri, 1030 Hitt St., Columbia, MO, 65211, USA
- Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia, MO, USA
| | - Faezeh Faghihi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Fereshteh Azedi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Armin Ariaei
- School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Mohamad Amin Habibi
- Clinical Research Development Center, Shahid Beheshti Hospital, Qom University of Medical Sciences, Qom, Iran
| | - Maryam Khalili
- School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Bahram Haghi Ashtiani
- Department of Neurology, Firouzgar Hospital, Iran University of Medical Sciences, Tehran, Iran
| | - Mohammad Taghi Joghataei
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - W David Arnold
- NextGen Precision Health, University of Missouri, 1030 Hitt St., Columbia, MO, 65211, USA.
- Department of Physical Medicine and Rehabilitation, University of Missouri, Columbia, MO, USA.
- Department of Neurology, University of Missouri, Columbia, MO, USA.
- Department of Medical Pharmacology and Physiology, University of Missouri, Columbia, MO, USA.
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3
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Lambert-Smith IA, Shephard VK, McAlary L, Yerbury JJ, Saunders DN. High-content analysis of proteostasis capacity in cellular models of amyotrophic lateral sclerosis (ALS). Sci Rep 2024; 14:13844. [PMID: 38879591 PMCID: PMC11180180 DOI: 10.1038/s41598-024-64366-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 06/07/2024] [Indexed: 06/19/2024] Open
Abstract
Disrupted proteome homeostasis (proteostasis) in amyotrophic lateral sclerosis (ALS) has been a major focus of research in the past two decades. However, the proteostasis processes that become disturbed in ALS are not fully understood. Obtaining more detailed knowledge of proteostasis disruption in association with different ALS-causing mutations will improve our understanding of ALS pathophysiology and may identify novel therapeutic targets and strategies for ALS patients. Here we describe the development and use of a novel high-content analysis (HCA) assay to investigate proteostasis disturbances caused by the expression of several ALS-causing gene variants. This assay involves the use of conformationally-destabilised mutants of firefly luciferase (Fluc) to examine protein folding/re-folding capacity in NSC-34 cells expressing ALS-associated mutations in the genes encoding superoxide dismutase-1 (SOD1A4V) and cyclin F (CCNFS621G). We demonstrate that these Fluc isoforms can be used in high-throughput format to report on reductions in the activity of the chaperone network that result from the expression of SOD1A4V, providing multiplexed information at single-cell resolution. In addition to SOD1A4V and CCNFS621G, NSC-34 models of ALS-associated TDP-43, FUS, UBQLN2, OPTN, VCP and VAPB mutants were generated that could be screened using this assay in future work. For ALS-associated mutant proteins that do cause reductions in protein quality control capacity, such as SOD1A4V, this assay has potential to be applied in drug screening studies to identify candidate compounds that can ameliorate this deficiency.
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Affiliation(s)
- Isabella A Lambert-Smith
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia.
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia.
| | - Victoria K Shephard
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Luke McAlary
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Justin J Yerbury
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia
- Molecular Horizons and School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - Darren N Saunders
- Illawarra Health and Medical Research Institute, University of Wollongong, Wollongong, NSW, 2522, Australia.
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4
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Buggiani J, Meinnel T, Giglione C, Frottin F. Advances in nuclear proteostasis of metazoans. Biochimie 2024:S0300-9084(24)00081-6. [PMID: 38642824 DOI: 10.1016/j.biochi.2024.04.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Revised: 04/12/2024] [Accepted: 04/16/2024] [Indexed: 04/22/2024]
Abstract
The proteostasis network and associated protein quality control (PQC) mechanisms ensure proteome functionality and are essential for cell survival. A distinctive feature of eukaryotic cells is their high degree of compartmentalization, requiring specific and adapted proteostasis networks for each compartment. The nucleus, essential for maintaining the integrity of genetic information and gene transcription, is one such compartment. While PQC mechanisms have been investigated for decades in the cytoplasm and the endoplasmic reticulum, our knowledge of nuclear PQC pathways is only emerging. Recent developments in the field have underscored the importance of spatially managing aberrant proteins within the nucleus. Upon proteotoxic stress, misfolded proteins and PQC effectors accumulate in various nuclear membrane-less organelles. Beyond bringing together effectors and substrates, the biophysical properties of these organelles allow novel PQC functions. In this review, we explore the specificity of the nuclear compartment, the effectors of the nuclear proteostasis network, and the PQC roles of nuclear membrane-less organelles in metazoans.
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Affiliation(s)
- Julia Buggiani
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Thierry Meinnel
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Carmela Giglione
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France
| | - Frédéric Frottin
- Institute for Integrative Biology of the Cell (I2BC), Université Paris-Saclay, CEA, CNRS, Gif-sur-Yvette, France.
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Lin L, Hu P, Luo M, Chen X, Xiao M, Zhong Z, Peng S, Chen G, Yang G, Zhang F, Zhang Y. CircNOP14 increases the radiosensitivity of hepatocellular carcinoma via inhibition of Ku70-dependent DNA damage repair. Int J Biol Macromol 2024; 264:130541. [PMID: 38460628 DOI: 10.1016/j.ijbiomac.2024.130541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2023] [Revised: 02/13/2024] [Accepted: 02/27/2024] [Indexed: 03/11/2024]
Abstract
Circular RNAs (circRNAs) are profoundly affected in hepatocellular carcinoma (HCC) through various pathways. However, the role of circRNAs in the radiosensitivity of HCC cells is yet to be explored. In this study, we identified a circRNA-hsa_circ_0006737 (circNOP14) involved in the radiosensitivity of HCC. We found that circNOP14 increased the radiosensitivity of HCC cells both in vitro and in vivo. Notably, using a circRNA pulldown assay and RNA-binding protein immunoprecipitation, we identified Ku70 as a novel and robust interacting protein of circNOP14. Mechanistically, circNOP14 interacts with Ku70 and prevents its nuclear translocation, thereby increasing irradiation-induced DNA damage. Therefore, our findings may provide a predictive indicator and intervention option for 125I brachytherapy or external radiotherapy in HCC.
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Affiliation(s)
- Letao Lin
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Pan Hu
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Ma Luo
- Department of Medical Imaging, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Xi Chen
- Department of Oncology, The Seventh Affiliated Hospital, Sun Yat-sen University, Shenzhen 518000, PR China
| | - Meigui Xiao
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Zhihui Zhong
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Sheng Peng
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Guanyu Chen
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Guang Yang
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China
| | - Fujun Zhang
- Department of Minimally Invasive Intervention, State Key Laboratory of Oncology in South China, Guangdong Provincial Clinical Research Center for Cancer, Sun Yat-sen University Cancer Center, Guangzhou 510060, PR China.
| | - Yanling Zhang
- School of Laboratory Medicine and Biotechnology, Southern Medical University, Guangzhou 510515, PR China.
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6
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Khalil B, Linsenmeier M, Smith CL, Shorter J, Rossoll W. Nuclear-import receptors as gatekeepers of pathological phase transitions in ALS/FTD. Mol Neurodegener 2024; 19:8. [PMID: 38254150 PMCID: PMC10804745 DOI: 10.1186/s13024-023-00698-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 12/13/2023] [Indexed: 01/24/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are fatal neurodegenerative disorders on a disease spectrum that are characterized by the cytoplasmic mislocalization and aberrant phase transitions of prion-like RNA-binding proteins (RBPs). The common accumulation of TAR DNA-binding protein-43 (TDP-43), fused in sarcoma (FUS), and other nuclear RBPs in detergent-insoluble aggregates in the cytoplasm of degenerating neurons in ALS/FTD is connected to nuclear pore dysfunction and other defects in the nucleocytoplasmic transport machinery. Recent advances suggest that beyond their canonical role in the nuclear import of protein cargoes, nuclear-import receptors (NIRs) can prevent and reverse aberrant phase transitions of TDP-43, FUS, and related prion-like RBPs and restore their nuclear localization and function. Here, we showcase the NIR family and how they recognize cargo, drive nuclear import, and chaperone prion-like RBPs linked to ALS/FTD. We also discuss the promise of enhancing NIR levels and developing potentiated NIR variants as therapeutic strategies for ALS/FTD and related neurodegenerative proteinopathies.
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Affiliation(s)
- Bilal Khalil
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, U.S.A
| | - Miriam Linsenmeier
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, U.S.A
| | - Courtney L Smith
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, U.S.A
- Mayo Clinic Graduate School of Biomedical Sciences, Neuroscience Track, Mayo Clinic, Jacksonville, FL, 32224, U.S.A
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, U.S.A..
| | - Wilfried Rossoll
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, U.S.A..
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7
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Rezvykh A, Shteinberg D, Bronovitsky E, Ustyugov A, Funikov S. Animal Models of FUS-Proteinopathy: A Systematic Review. BIOCHEMISTRY. BIOKHIMIIA 2024; 89:S34-S56. [PMID: 38621743 DOI: 10.1134/s0006297924140037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/01/2023] [Accepted: 09/07/2023] [Indexed: 04/17/2024]
Abstract
Mutations that disrupt the function of the DNA/RNA-binding protein FUS could cause amyotrophic lateral sclerosis (ALS) and other neurodegenerative diseases. One of the key features in ALS pathogenesis is the formation of insoluble protein aggregates containing aberrant isoforms of the FUS protein in the cytoplasm of upper and lower motor neurons. Reproduction of human pathology in animal models is the main tool for studying FUS-associated pathology and searching for potential therapeutic agents for ALS treatment. In this review, we provide a systematic analysis of the role of FUS protein in ALS pathogenesis and an overview of the results of modelling FUS-proteinopathy in animals.
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Affiliation(s)
- Alexander Rezvykh
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia
| | - Daniil Shteinberg
- Institute of Physiologically Active Compounds, Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | | | - Aleksey Ustyugov
- Institute of Physiologically Active Compounds, Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry, Russian Academy of Sciences, Chernogolovka, 142432, Russia
| | - Sergei Funikov
- Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow, 119991, Russia.
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8
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Yang Y, Guo L, Chen L, Gong B, Jia D, Sun Q. Nuclear transport proteins: structure, function, and disease relevance. Signal Transduct Target Ther 2023; 8:425. [PMID: 37945593 PMCID: PMC10636164 DOI: 10.1038/s41392-023-01649-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 11/12/2023] Open
Abstract
Proper subcellular localization is crucial for the functioning of biomacromolecules, including proteins and RNAs. Nuclear transport is a fundamental cellular process that regulates the localization of many macromolecules within the nuclear or cytoplasmic compartments. In humans, approximately 60 proteins are involved in nuclear transport, including nucleoporins that form membrane-embedded nuclear pore complexes, karyopherins that transport cargoes through these complexes, and Ran system proteins that ensure directed and rapid transport. Many of these nuclear transport proteins play additional and essential roles in mitosis, biomolecular condensation, and gene transcription. Dysregulation of nuclear transport is linked to major human diseases such as cancer, neurodegenerative diseases, and viral infections. Selinexor (KPT-330), an inhibitor targeting the nuclear export factor XPO1 (also known as CRM1), was approved in 2019 to treat two types of blood cancers, and dozens of clinical trials of are ongoing. This review summarizes approximately three decades of research data in this field but focuses on the structure and function of individual nuclear transport proteins from recent studies, providing a cutting-edge and holistic view on the role of nuclear transport proteins in health and disease. In-depth knowledge of this rapidly evolving field has the potential to bring new insights into fundamental biology, pathogenic mechanisms, and therapeutic approaches.
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Affiliation(s)
- Yang Yang
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Lu Guo
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Lin Chen
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Bo Gong
- The Key Laboratory for Human Disease Gene Study of Sichuan Province and Department of Laboratory Medicine, Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Research Unit for Blindness Prevention of Chinese Academy of Medical Sciences (2019RU026), Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, Chengdu, China
| | - Da Jia
- Key Laboratory of Birth Defects and Related Diseases of Women and Children, Department of Pediatrics, West China Second University Hospital, State Key Laboratory of Biotherapy, Sichuan University, Chengdu, China.
| | - Qingxiang Sun
- Department of Pulmonary and Critical Care Medicine, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China.
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, China.
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9
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Motaln H, ÄerÄek U, Yamoah A, Tripathi P, Aronica E, Goswami A, Rogelj B. Abl kinase-mediated FUS Tyr526 phosphorylation alters nucleocytoplasmic FUS localization in FTLD-FUS. Brain 2023; 146:4088-4104. [PMID: 37071594 PMCID: PMC10545532 DOI: 10.1093/brain/awad130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 03/02/2023] [Accepted: 03/28/2023] [Indexed: 04/19/2023] Open
Abstract
Nuclear to cytoplasmic mislocalization and aggregation of multiple RNA-binding proteins (RBPs), including FUS, are the main neuropathological features of the majority of cases of amyotrophic lateral sclerosis (ALS) and frontotemporal lobular degeneration (FTLD). In ALS-FUS, these aggregates arise from disease-associated mutations in FUS, whereas in FTLD-FUS, the cytoplasmic inclusions do not contain mutant FUS, suggesting different molecular mechanisms of FUS pathogenesis in FTLD that remain to be investigated. We have previously shown that phosphorylation of the C-terminal Tyr526 of FUS results in increased cytoplasmic retention of FUS due to impaired binding to the nuclear import receptor TNPO1. Inspired by the above notions, in the current study we developed a novel antibody against the C-terminally phosphorylated Tyr526 FUS (FUSp-Y526) that is specifically capable of recognizing phosphorylated cytoplasmic FUS, which is poorly recognized by other commercially available FUS antibodies. Using this FUSp-Y526 antibody, we demonstrated a FUS phosphorylation-specific effect on the cytoplasmic distribution of soluble and insoluble FUSp-Y526 in various cells and confirmed the involvement of the Src kinase family in Tyr526 FUS phosphorylation. In addition, we found that FUSp-Y526 expression pattern correlates with active pSrc/pAbl kinases in specific brain regions of mice, indicating preferential involvement of cAbl in the cytoplasmic mislocalization of FUSp-Y526 in cortical neurons. Finally, the pattern of immunoreactivity of active cAbl kinase and FUSp-Y526 revealed altered cytoplasmic distribution of FUSp-Y526 in cortical neurons of post-mortem frontal cortex tissue from FTLD patients compared with controls. The overlap of FUSp-Y526 and FUS signals was found preferentially in small diffuse inclusions and was absent in mature aggregates, suggesting possible involvement of FUSp-Y526 in the formation of early toxic FUS aggregates in the cytoplasm that are largely undetected by commercially available FUS antibodies. Given the overlapping patterns of cAbl activity and FUSp-Y526 distribution in cortical neurons, and cAbl induced sequestration of FUSp-Y526 into G3BP1 positive granules in stressed cells, we propose that cAbl kinase is actively involved in mediating cytoplasmic mislocalization and promoting toxic aggregation of wild-type FUS in the brains of FTLD patients, as a novel putative underlying mechanism of FTLD-FUS pathophysiology and progression.
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Affiliation(s)
- Helena Motaln
- Department of Biotechnology, JoĆŸef Stefan Institute, SI-1000 Ljubljana, Slovenia
| | - UrĆĄa ÄerÄek
- Department of Biotechnology, JoĆŸef Stefan Institute, SI-1000 Ljubljana, Slovenia
- Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Alfred Yamoah
- Institute of Neuropathology, RWTH Aachen University Medical School, 52074 Aachen, Germany
| | - Priyanka Tripathi
- Institute of Neuropathology, RWTH Aachen University Medical School, 52074 Aachen, Germany
| | - Eleonora Aronica
- Amsterdam UMC location University of Amsterdam, Department of Neuropathology, Amsterdam Neuroscience, 1105 Amsterdam, The Netherlands
| | - Anand Goswami
- Institute of Neuropathology, RWTH Aachen University Medical School, 52074 Aachen, Germany
- Department of Neurology, Center for Motor Neuron Biology and Disease, Columbia University, New York, NY 10032, USA
- Department of Neurology, Eleanor and Lou Gherig ALS Center, Columbia University, New York, NY 10032, USA
| | - Boris Rogelj
- Department of Biotechnology, JoĆŸef Stefan Institute, SI-1000 Ljubljana, Slovenia
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
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10
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Tzeplaeff L, Seguin J, Le Gras S, Megat S, Cosquer B, Plassard D, Dieterlé S, Paiva I, Picchiarelli G, Decraene C, Alcala-Vida R, Cassel JC, Merienne K, Dupuis L, Boutillier AL. Mutant FUS induces chromatin reorganization in the hippocampus and alters memory processes. Prog Neurobiol 2023; 227:102483. [PMID: 37327984 DOI: 10.1016/j.pneurobio.2023.102483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 05/12/2023] [Accepted: 06/09/2023] [Indexed: 06/18/2023]
Abstract
Cytoplasmic mislocalization of the nuclear Fused in Sarcoma (FUS) protein is associated to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Cytoplasmic FUS accumulation is recapitulated in the frontal cortex and spinal cord of heterozygous FusâNLS/+ mice. Yet, the mechanisms linking FUS mislocalization to hippocampal function and memory formation are still not characterized. Herein, we show that in these mice, the hippocampus paradoxically displays nuclear FUS accumulation. Multi-omic analyses showed that FUS binds to a set of genes characterized by the presence of an ETS/ELK-binding motifs, and involved in RNA metabolism, transcription, ribosome/mitochondria and chromatin organization. Importantly, hippocampal nuclei showed a decompaction of the neuronal chromatin at highly expressed genes and an inappropriate transcriptomic response was observed after spatial training of FusâNLS/+ mice. Furthermore, these mice lacked precision in a hippocampal-dependent spatial memory task and displayed decreased dendritic spine density. These studies shows that mutated FUS affects epigenetic regulation of the chromatin landscape in hippocampal neurons, which could participate in FTD/ALS pathogenic events. These data call for further investigation in the neurological phenotype of FUS-related diseases and open therapeutic strategies towards epigenetic drugs.
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Affiliation(s)
- Laura Tzeplaeff
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France; Université de Strasbourg, INSERM, UMR-S1118, Strasbourg, France
| | - Jonathan Seguin
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Stéphanie Le Gras
- Université de Strasbourg, CNRS UMR 7104, INSERM U1258, GenomEast Platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | - Salim Megat
- Université de Strasbourg, INSERM, UMR-S1118, Strasbourg, France
| | - Brigitte Cosquer
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Damien Plassard
- Université de Strasbourg, CNRS UMR 7104, INSERM U1258, GenomEast Platform, Institut de Génétique et de Biologie Moléculaire et Cellulaire (IGBMC), Université de Strasbourg, Illkirch, France
| | | | - Isabel Paiva
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | | | - Charles Decraene
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Rafael Alcala-Vida
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Jean-Christophe Cassel
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Karine Merienne
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France; CNRS, UMR 7364, Strasbourg 67000, France
| | - Luc Dupuis
- Université de Strasbourg, INSERM, UMR-S1118, Strasbourg, France.
| | - Anne-Laurence Boutillier
- Université de Strasbourg, Laboratoire de Neuroscience Cognitives et Adaptatives (LNCA), Strasbourg, France.
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11
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Seidel M, Romanov N, Obarska-Kosinska A, Becker A, Trevisan Doimo de Azevedo N, Provaznik J, Nagaraja SR, Landry JJM, Benes V, Beck M. Co-translational binding of importins to nascent proteins. Nat Commun 2023; 14:3418. [PMID: 37296145 PMCID: PMC10256725 DOI: 10.1038/s41467-023-39150-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Accepted: 05/26/2023] [Indexed: 06/12/2023] Open
Abstract
Various cellular quality control mechanisms support proteostasis. While, ribosome-associated chaperones prevent the misfolding of nascent chains during translation, importins were shown to prevent the aggregation of specific cargoes in a post-translational mechanism prior the import into the nucleoplasm. Here, we hypothesize that importins may already bind ribosome-associated cargo in a co-translational manner. We systematically measure the nascent chain association of all importins in Saccharomyces cerevisiae by selective ribosome profiling. We identify a subset of importins that bind to a wide range of nascent, often uncharacterized cargoes. This includes ribosomal proteins, chromatin remodelers and RNA binding proteins that are aggregation prone in the cytosol. We show that importins act consecutively with other ribosome-associated chaperones. Thus, the nuclear import system is directly intertwined with nascent chain folding and chaperoning.
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Affiliation(s)
- Maximilian Seidel
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
- Faculty of Bioscience, Heidelberg University, Heidelberg, Germany
| | - Natalie Romanov
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | | | - Anja Becker
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | | | - Jan Provaznik
- Genomics Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Sankarshana R Nagaraja
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany
| | - Jonathan J M Landry
- Genomics Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Vladimir Benes
- Genomics Core Facility, European Molecular Biology Laboratory (EMBL), Heidelberg, Germany
| | - Martin Beck
- Department of Molecular Sociology, Max Planck Institute of Biophysics, Frankfurt, Germany.
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt, Germany.
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12
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Fare CM, Rhine K, Lam A, Myong S, Shorter J. A minimal construct of nuclear-import receptor Karyopherin-ÎČ2 defines the regions critical for chaperone and disaggregation activity. J Biol Chem 2023; 299:102806. [PMID: 36529289 PMCID: PMC9860449 DOI: 10.1016/j.jbc.2022.102806] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 12/02/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
Karyopherin-ÎČ2 (KapÎČ2) is a nuclear-import receptor that recognizes proline-tyrosine nuclear localization signals of diverse cytoplasmic cargo for transport to the nucleus. KapÎČ2 cargo includes several disease-linked RNA-binding proteins with prion-like domains, such as FUS, TAF15, EWSR1, hnRNPA1, and hnRNPA2. These RNA-binding proteins with prion-like domains are linked via pathology and genetics to debilitating degenerative disorders, including amyotrophic lateral sclerosis, frontotemporal dementia, and multisystem proteinopathy. Remarkably, KapÎČ2 prevents and reverses aberrant phase transitions of these cargoes, which is cytoprotective. However, the molecular determinants of KapÎČ2 that enable these activities remain poorly understood, particularly from the standpoint of nuclear-import receptor architecture. KapÎČ2 is a super-helical protein comprised of 20 HEAT repeats. Here, we design truncated variants of KapÎČ2 and assess their ability to antagonize FUS aggregation and toxicity in yeast and FUS condensation at the pure protein level and in human cells. We find that HEAT repeats 8 to 20 of KapÎČ2 recapitulate all salient features of KapÎČ2 activity. By contrast, KapÎČ2 truncations lacking even a single cargo-binding HEAT repeat display reduced activity. Thus, we define a minimal KapÎČ2 construct for delivery in adeno-associated viruses as a potential therapeutic for amyotrophic lateral sclerosis/frontotemporal dementia, multisystem proteinopathy, and related disorders.
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Affiliation(s)
- Charlotte M Fare
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kevin Rhine
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland, USA; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - Andrew Lam
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sua Myong
- Program in Cell, Molecular, Developmental Biology, and Biophysics, Johns Hopkins University, Baltimore, Maryland, USA; Department of Biophysics, Johns Hopkins University, Baltimore, Maryland, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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13
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Khalil B, Chhangani D, Wren MC, Smith CL, Lee JH, Li X, Puttinger C, Tsai CW, Fortin G, Morderer D, Gao J, Liu F, Lim CK, Chen J, Chou CC, Croft CL, Gleixner AM, Donnelly CJ, Golde TE, Petrucelli L, Oskarsson B, Dickson DW, Zhang K, Shorter J, Yoshimura SH, Barmada SJ, Rincon-Limas DE, Rossoll W. Nuclear import receptors are recruited by FG-nucleoporins to rescue hallmarks of TDP-43 proteinopathy. Mol Neurodegener 2022; 17:80. [PMID: 36482422 PMCID: PMC9733332 DOI: 10.1186/s13024-022-00585-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 11/23/2022] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Cytoplasmic mislocalization and aggregation of TAR DNA-binding protein-43 (TDP-43) is a hallmark of the amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD) disease spectrum, causing both nuclear loss-of-function and cytoplasmic toxic gain-of-function phenotypes. While TDP-43 proteinopathy has been associated with defects in nucleocytoplasmic transport, this process is still poorly understood. Here we study the role of karyopherin-ÎČ1 (KPNB1) and other nuclear import receptors in regulating TDP-43 pathology. METHODS We used immunostaining, immunoprecipitation, biochemical and toxicity assays in cell lines, primary neuron and organotypic mouse brain slice cultures, to determine the impact of KPNB1 on the solubility, localization, and toxicity of pathological TDP-43 constructs. Postmortem patient brain and spinal cord tissue was stained to assess KPNB1 colocalization with TDP-43 inclusions. Turbidity assays were employed to study the dissolution and prevention of aggregation of recombinant TDP-43 fibrils in vitro. Fly models of TDP-43 proteinopathy were used to determine the effect of KPNB1 on their neurodegenerative phenotype in vivo. RESULTS We discovered that several members of the nuclear import receptor protein family can reduce the formation of pathological TDP-43 aggregates. Using KPNB1 as a model, we found that its activity depends on the prion-like C-terminal region of TDP-43, which mediates the co-aggregation with phenylalanine and glycine-rich nucleoporins (FG-Nups) such as Nup62. KPNB1 is recruited into these co-aggregates where it acts as a molecular chaperone that reverses aberrant phase transition of Nup62 and TDP-43. These findings are supported by the discovery that Nup62 and KPNB1 are also sequestered into pathological TDP-43 aggregates in ALS/FTD postmortem CNS tissue, and by the identification of the fly ortholog of KPNB1 as a strong protective modifier in Drosophila models of TDP-43 proteinopathy. Our results show that KPNB1 can rescue all hallmarks of TDP-43 pathology, by restoring its solubility and nuclear localization, and reducing neurodegeneration in cellular and animal models of ALS/FTD. CONCLUSION Our findings suggest a novel NLS-independent mechanism where, analogous to its canonical role in dissolving the diffusion barrier formed by FG-Nups in the nuclear pore, KPNB1 is recruited into TDP-43/FG-Nup co-aggregates present in TDP-43 proteinopathies and therapeutically reverses their deleterious phase transition and mislocalization, mitigating neurodegeneration.
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Affiliation(s)
- Bilal Khalil
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Deepak Chhangani
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, 32610, USA
| | - Melissa C Wren
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Courtney L Smith
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
- Mayo Clinic Graduate School of Biomedical Sciences, Neuroscience Track, Mayo Clinic, Jacksonville, FL, USA
| | - Jannifer H Lee
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
- Mayo Clinic Graduate School of Biomedical Sciences, Neuroscience Track, Mayo Clinic, Jacksonville, FL, USA
| | - Xingli Li
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | | | - Chih-Wei Tsai
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Gael Fortin
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Dmytro Morderer
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Junli Gao
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Feilin Liu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Chun Kim Lim
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto, Japan
| | - Jingjiao Chen
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
- Geriatric Department, Affiliated Hospital of Qingdao University, Qingdao, Shandong, China
| | - Ching-Chieh Chou
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Cara L Croft
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
- UK Dementia Research Institute at University College London, London, UK
| | - Amanda M Gleixner
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, 15261, USA
| | - Christopher J Donnelly
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15213, USA
- LiveLikeLou Center for ALS Research, University of Pittsburgh Brain Institute, Pittsburgh, PA, 15261, USA
| | - Todd E Golde
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, 32610, USA
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
| | | | | | - Dennis W Dickson
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - Ke Zhang
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Shige H Yoshimura
- Graduate School of Biostudies, Kyoto University, Yoshida-konoe, Sakyo-ku, Kyoto, Japan
| | - Sami J Barmada
- Department of Neurology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Diego E Rincon-Limas
- Department of Neurology, McKnight Brain Institute, Norman Fixel Institute for Neurological Diseases, University of Florida, Gainesville, FL, 32610, USA
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, University of Florida, Gainesville, FL, 32610, USA
- Genetics Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Wilfried Rossoll
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, 32224, USA.
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14
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Di Liegro CM, Schiera G, SchirĂČ G, Di Liegro I. RNA-Binding Proteins as Epigenetic Regulators of Brain Functions and Their Involvement in Neurodegeneration. Int J Mol Sci 2022; 23:ijms232314622. [PMID: 36498959 PMCID: PMC9739182 DOI: 10.3390/ijms232314622] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/18/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022] Open
Abstract
A central aspect of nervous system development and function is the post-transcriptional regulation of mRNA fate, which implies time- and site-dependent translation, in response to cues originating from cell-to-cell crosstalk. Such events are fundamental for the establishment of brain cell asymmetry, as well as of long-lasting modifications of synapses (long-term potentiation: LTP), responsible for learning, memory, and higher cognitive functions. Post-transcriptional regulation is in turn dependent on RNA-binding proteins that, by recognizing and binding brief RNA sequences, base modifications, or secondary/tertiary structures, are able to control maturation, localization, stability, and translation of the transcripts. Notably, most RBPs contain intrinsically disordered regions (IDRs) that are thought to be involved in the formation of membrane-less structures, probably due to liquid-liquid phase separation (LLPS). Such structures are evidenced as a variety of granules that contain proteins and different classes of RNAs. The other side of the peculiar properties of IDRs is, however, that, under altered cellular conditions, they are also prone to form aggregates, as observed in neurodegeneration. Interestingly, RBPs, as part of both normal and aggregated complexes, are also able to enter extracellular vesicles (EVs), and in doing so, they can also reach cells other than those that produced them.
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Affiliation(s)
- Carlo Maria Di Liegro
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche) (STEBICEF), University of Palermo, 90128 Palermo, Italy
| | - Gabriella Schiera
- Department of Biological, Chemical and Pharmaceutical Sciences and Technologies (Dipartimento di Scienze e Tecnologie Biologiche, Chimiche e Farmaceutiche) (STEBICEF), University of Palermo, 90128 Palermo, Italy
| | - Giuseppe SchirĂČ
- Department of Biomedicine, Neurosciences and Advanced Diagnostics (Dipartimento di Biomedicina, Neuroscienze e Diagnostica Avanzata) (Bi.N.D.), University of Palermo, 90127 Palermo, Italy
| | - Italia Di Liegro
- Department of Biomedicine, Neurosciences and Advanced Diagnostics (Dipartimento di Biomedicina, Neuroscienze e Diagnostica Avanzata) (Bi.N.D.), University of Palermo, 90127 Palermo, Italy
- Correspondence: ; Tel.: +39-091-238-97 (ext. 415/446)
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15
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Damizia M, Altieri L, Lavia P. Non-transport roles of nuclear import receptors: In need of the right balance. Front Cell Dev Biol 2022; 10:1041938. [PMID: 36438555 PMCID: PMC9686011 DOI: 10.3389/fcell.2022.1041938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2022] [Accepted: 10/21/2022] [Indexed: 11/12/2023] Open
Abstract
Nuclear import receptors ensure the recognition and transport of proteins across the nuclear envelope into the nucleus. In addition, as diverse processes as mitosis, post-translational modifications at mitotic exit, ciliogenesis, and phase separation, all share a common need for regulation by nuclear import receptors - particularly importin beta-1 and importin beta-2/transportin - independent on nuclear import. In particular, 1) nuclear import receptors regulate the mitotic spindle after nuclear envelope breakdown, 2) they shield cargoes from unscheduled ubiquitination, regulating their timely proteolysis; 3) they regulate ciliary factors, crucial to cell communications and tissue architecture during development; and 4) they prevent phase separation of toxic proteins aggregates in neurons. The balance of nuclear import receptors to cargoes is critical in all these processes, albeit in opposite directions: overexpression of import receptors, as often found in cancer, inhibits cargoes and impairs downstream processes, motivating the therapeutic design of specific inhibitors. On the contrary, elevated expression is beneficial in neuronal contexts, where nuclear import receptors are regarded as potential therapeutic tools in counteracting the formation of aggregates that may cause neurodegeneration. This paradox demonstrates the amplitude of nuclear import receptors-dependent functions in different contexts and adds complexity in considering their therapeutic implications.
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Affiliation(s)
- Michela Damizia
- Department of Cellular, Computational and Integrated Biology (CIBIO), University of Trento, Trento, Italy
| | - Ludovica Altieri
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology âCharles Darwinâ, Sapienza University of Rome, Rome, Italy
| | - Patrizia Lavia
- Institute of Molecular Biology and Pathology (IBPM), CNR National Research Council of Italy, Sapienza University of Rome, Rome, Italy
- Department of Biology and Biotechnology âCharles Darwinâ, Sapienza University of Rome, Rome, Italy
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16
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Regulating Phase Transition in Neurodegenerative Diseases by Nuclear Import Receptors. BIOLOGY 2022; 11:biology11071009. [PMID: 36101390 PMCID: PMC9311884 DOI: 10.3390/biology11071009] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 06/12/2022] [Accepted: 06/16/2022] [Indexed: 11/17/2022]
Abstract
RNA-binding proteins (RBPs) with a low-complexity prion-like domain (PLD) can undergo aberrant phase transitions and have been implicated in neurodegenerative diseases such as ALS and FTD. Several nuclear RBPs mislocalize to cytoplasmic inclusions in disease conditions. Impairment in nucleocytoplasmic transport is another major event observed in ageing and in neurodegenerative disorders. Nuclear import receptors (NIRs) regulate the nucleocytoplasmic transport of different RBPs bearing a nuclear localization signal by restoring their nuclear localization. NIRs can also specifically dissolve or prevent the aggregation and liquidâliquid phase separation of wild-type or disease-linked mutant RBPs, due to their chaperoning activity. This review focuses on the LLPS of intrinsically disordered proteins and the role of NIRs in regulating LLPS in neurodegeneration. This review also discusses the implication of NIRs as therapeutic agents in neurogenerative diseases.
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17
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Johnson MA, Nuckols TA, Merino P, Bagchi P, Nandy S, Root J, Taylor G, Seyfried NT, Kukar T. Proximity-based labeling reveals DNA damage-induced phosphorylation of fused in sarcoma (FUS) causes distinct changes in the FUS protein interactome. J Biol Chem 2022; 298:102135. [PMID: 35709984 PMCID: PMC9372748 DOI: 10.1016/j.jbc.2022.102135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 05/13/2022] [Accepted: 05/14/2022] [Indexed: 01/18/2023] Open
Abstract
Accumulation of cytoplasmic inclusions containing fused in sarcoma (FUS), an RNA/DNA-binding protein, is a common hallmark of frontotemporal lobar degeneration and amyotrophic lateral sclerosis neuropathology. We have previously shown that DNA damage can trigger the cytoplasmic accumulation of N-terminally phosphorylated FUS. However, the functional consequences of N-terminal FUS phosphorylation are unknown. To gain insight into this question, we utilized proximity-dependent biotin labeling via ascorbate peroxidase 2 aired with mass spectrometry to investigate whether N-terminal phosphorylation alters the FUS protein-protein interaction network (interactome), and subsequently, FUS function. We report the first analysis comparing the interactomes of three FUS variants: homeostatic wildtype FUS (FUS WT), phosphomimetic FUS (FUS PM; a proxy for N-terminally phosphorylated FUS), and the toxic FUS proline 525 to leucine mutant (FUS P525L) that causes juvenile amyotrophic lateral sclerosis. We found that the phosphomimetic FUS interactome is uniquely enriched for a group of cytoplasmic proteins that mediate mRNA metabolism and translation, as well as nuclear proteins involved in the spliceosome and DNA repair functions. Furthermore, we identified and validated the RNA-induced silencing complex RNA helicase MOV10 as a novel interacting partner of FUS. Finally, we provide functional evidence that N-terminally phosphorylated FUS may disrupt homeostatic translation and steady-state levels of specific mRNA transcripts. Taken together, these results highlight phosphorylation as a unique modulator of the interactome and function of FUS.
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Affiliation(s)
- Michelle A. Johnson
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Thomas A. Nuckols
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Paola Merino
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Pritha Bagchi
- Emory Integrated Proteomics Core, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Srijita Nandy
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Jessica Root
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Georgia Taylor
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Nicholas T. Seyfried
- Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA,Emory Integrated Proteomics Core, Emory University, School of Medicine, Atlanta, Georgia, USA,Department of Neurology, Emory University, School of Medicine, Atlanta, Georgia, USA,Department of Biochemistry, Emory University, School of Medicine, Atlanta, Georgia, USA
| | - Thomas Kukar
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta, Georgia, USA,Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta, Georgia, USA,Department of Neurology, Emory University, School of Medicine, Atlanta, Georgia, USA,For correspondence: Thomas Kukar
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18
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Carey JL, Guo L. Liquid-Liquid Phase Separation of TDP-43 and FUS in Physiology and Pathology of Neurodegenerative Diseases. Front Mol Biosci 2022; 9:826719. [PMID: 35187086 PMCID: PMC8847598 DOI: 10.3389/fmolb.2022.826719] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 01/11/2022] [Indexed: 12/12/2022] Open
Abstract
Liquid-liquid phase separation of RNA-binding proteins mediates the formation of numerous membraneless organelles with essential cellular function. However, aberrant phase transition of these proteins leads to the formation of insoluble protein aggregates, which are pathological hallmarks of neurodegenerative diseases including ALS and FTD. TDP-43 and FUS are two such RNA-binding proteins that mislocalize and aggregate in patients of ALS and FTD. They have similar domain structures that provide multivalent interactions driving their phase separation in vitro and in the cellular environment. In this article, we review the factors that mediate and regulate phase separation of TDP-43 and FUS. We also review evidences that connect the phase separation property of TDP-43 and FUS to their functional roles in cells. Aberrant phase transition of TDP-43 and FUS leads to protein aggregation and disrupts their regular cell function. Therefore, restoration of functional protein phase of TDP-43 and FUS could be beneficial for neuronal cells. We discuss possible mechanisms for TDP-43 and FUS aberrant phase transition and aggregation while reviewing the methods that are currently being explored as potential therapeutic strategies to mitigate aberrant phase transition and aggregation of TDP-43 and FUS.
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19
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Wing CE, Fung HYJ, Chook YM. Karyopherin-mediated nucleocytoplasmic transport. Nat Rev Mol Cell Biol 2022; 23:307-328. [PMID: 35058649 PMCID: PMC10101760 DOI: 10.1038/s41580-021-00446-7] [Citation(s) in RCA: 107] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/09/2021] [Indexed: 12/25/2022]
Abstract
Efficient and regulated nucleocytoplasmic trafficking of macromolecules to the correct subcellular compartment is critical for proper functions of the eukaryotic cell. The majority of the macromolecular traffic across the nuclear pores is mediated by the Karyopherin-ÎČ (or Kap) family of nuclear transport receptors. Work over more than two decades has shed considerable light on how the different Kap family members bring their respective cargoes into the nucleus or the cytoplasm in efficient and highly regulated manners. In this Review, we overview the main features and established functions of Kap family members, describe how Kaps recognize their cargoes and discuss the different ways in which these Kap-cargo interactions can be regulated, highlighting new findings and open questions. We also describe current knowledge of the import and export of the components of three large gene expression machines - the core replisome, RNA polymerase II and the ribosome - pointing out the questions that persist about how such large macromolecular complexes are trafficked to serve their function in a designated subcellular location.
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20
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Odeh HM, Fare CM, Shorter J. Nuclear-Import Receptors Counter Deleterious Phase Transitions in Neurodegenerative Disease. J Mol Biol 2022; 434:167220. [PMID: 34464655 PMCID: PMC8748273 DOI: 10.1016/j.jmb.2021.167220] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/20/2021] [Accepted: 08/24/2021] [Indexed: 01/17/2023]
Abstract
Nuclear-import receptors (NIRs) engage nuclear-localization signals (NLSs) of polypeptides in the cytoplasm and transport these cargo across the size-selective barrier of the nuclear-pore complex into the nucleoplasm. Beyond this canonical role in nuclear transport, NIRs operate in the cytoplasm to chaperone and disaggregate NLS-bearing clients. Indeed, NIRs can inhibit and reverse functional and deleterious phase transitions of their cargo, including several prominent neurodegenerative disease-linked RNA-binding proteins (RBPs) with prion-like domains (PrLDs), such as TDP-43, FUS, EWSR1, TAF15, hnRNPA1, and hnRNPA2. Importantly, elevated NIR expression can mitigate degenerative phenotypes connected to aberrant cytoplasmic aggregation of RBPs with PrLDs. Here, we review recent discoveries that NIRs can also antagonize aberrant interactions and toxicity of arginine-rich, dipeptide-repeat proteins that are associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) caused by G4C2 hexanucleotide repeat expansions in the first intron of C9ORF72. We also highlight recent findings that multiple NIR family members can prevent and reverse liquid-liquid phase separation of specific clients bearing RGG motifs in an NLS-independent manner. Finally, we discuss strategies to enhance NIR activity or expression, which could have therapeutic utility for several neurodegenerative disorders, including ALS, FTD, multisystem proteinopathy, limbic-predominant age-related TDP-43 encephalopathy, tauopathies, and related diseases.
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Affiliation(s)
- Hana M Odeh
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Charlotte M Fare
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA. https://twitter.com/CharlotteFare
| | - James Shorter
- Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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21
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Notaro A, Messina A, La Bella V. A Deletion of the Nuclear Localization Signal Domain in the Fus Protein Induces Stable Post-stress Cytoplasmic Inclusions in SH-SY5Y Cells. Front Neurosci 2022; 15:759659. [PMID: 35002600 PMCID: PMC8733393 DOI: 10.3389/fnins.2021.759659] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 12/07/2021] [Indexed: 12/28/2022] Open
Abstract
Mutations in Fused-in-Sarcoma (FUS) gene involving the nuclear localization signal (NLS) domain lead to juvenile-onset Amyotrophic Lateral Sclerosis (ALS). The mutant protein mislocalizes to the cytoplasm, incorporating it into Stress Granules (SG). Whether SGs are the first step to the formation of stable FUS-containing aggregates is still unclear. In this work, we used acute and chronic stress paradigms to study the SG dynamics in a human SH-SY5Y neuroblastoma cell line carrying a deletion of the NLS domain of the FUS protein (homozygous: ÎNLSâ/â; heterozygous: ÎNLS+/â). Wild-type (WT) cells served as controls. We evaluated the subcellular localization of the mutant protein through immunoblot and immunofluorescence, in basal conditions and after acute stress and chronic stress with sodium arsenite (NaAsO2). Cells were monitored for up to 24 h after rescue. FUS was expressed in both nucleus and cytoplasm in the ÎNLS+/â cells, whereas it was primarily cytoplasmic in the ÎNLSâ/â. Acute NaAsO2 exposure induced SGs: at rescue,>90% of ÎNLS cells showed abundant FUS-containing if compared to less than 5% of the WT cells. The proportion of FUS-positive SGs remained 15â20% at 24 h in mutant cells. Cycloheximide did not abolish the long-lasting SGs in mutant cells. Chronic exposure to NaAsO2 did not induce significant SGs formation. A wealth of research has demonstrated that ALS-associated FUS mutations at the C-terminus facilitate the incorporation of the mutant protein into SGs. We have shown here that mutant FUS-containing SGs tend to fail to dissolve after stress, facilitating a liquid-to-solid phase transition. The FUS-containing inclusions seen in the dying motor neurons might therefore directly derive from SGs. This might represent an attractive target for future innovative therapies.
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Affiliation(s)
- Antonietta Notaro
- ALS Clinical Research Center and Laboratory of Neurochemistry, Department of Biomedicine, Neuroscience and Advances Diagnostics, University of Palermo, Palermo, Italy
| | - Antonella Messina
- ALS Clinical Research Center and Laboratory of Neurochemistry, Department of Biomedicine, Neuroscience and Advances Diagnostics, University of Palermo, Palermo, Italy
| | - Vincenzo La Bella
- ALS Clinical Research Center and Laboratory of Neurochemistry, Department of Biomedicine, Neuroscience and Advances Diagnostics, University of Palermo, Palermo, Italy
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22
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Yao J, Tu Y, Shen C, Zhou Q, Xiao H, Jia D, Sun Q. Nuclear import receptors and hnRNPK mediates nuclear import and stress granule localization of SIRLOIN. Cell Mol Life Sci 2021; 78:7617-7633. [PMID: 34689235 PMCID: PMC11073023 DOI: 10.1007/s00018-021-03992-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 10/08/2021] [Accepted: 10/11/2021] [Indexed: 02/08/2023]
Abstract
The majority of lncRNAs and a small fraction of mRNAs localize in the cell nucleus to exert their functions. A SIRLOIN RNA motif was previously reported to drive its nuclear localization by the RNA-binding protein hnRNPK. However, the underlying mechanism remains unclear. Here, we report crystal structures of hnRNPK in complex with SIRLOIN, and with the nuclear import receptor (NIR) Impα1, respectively. The protein hnRNPK bound to SIRLOIN with multiple weak interactions, and interacted Impα1 using an independent high-affinity site. Forming a complex with hnRNPK and Impα1 was essential for the nuclear import and stress granule localization of SIRLOIN in semi-permeabilized cells. Nuclear import of SIRLOIN enhanced with increasing NIR concentrations, but its stress granule localization peaked at a low NIR concentration. Collectively, we propose a mechanism of SIRLOIN localization, in which NIRs functioned as drivers/regulators, and hnRNPK as an adaptor.
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Affiliation(s)
- Jialin Yao
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, 610041, China
| | - Yingfeng Tu
- Division of Neurology, Department of Pediatrics, Key Laboratory of Birth Defects and Related Diseases of Women and Children, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Congcong Shen
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, 610041, China
| | - Qiao Zhou
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, 610041, China
| | - Hengyi Xiao
- Aging Research Lab, National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, 610041, China
| | - Da Jia
- Division of Neurology, Department of Pediatrics, Key Laboratory of Birth Defects and Related Diseases of Women and Children, West China Second University Hospital, Sichuan University, Chengdu, 610041, China
| | - Qingxiang Sun
- Department of Pathology, State Key Laboratory of Biotherapy and Cancer Centre, West China Hospital, Sichuan University, and Collaborative Innovation Centre of Biotherapy, Chengdu, 610041, China.
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23
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Trnka F, Hoffmann C, Wang H, Sansevrino R, Rankovic B, Rost BR, Schmitz D, Schmidt HB, Milovanovic D. Aberrant Phase Separation of FUS Leads to Lysosome Sequestering and Acidification. Front Cell Dev Biol 2021; 9:716919. [PMID: 34746121 PMCID: PMC8569517 DOI: 10.3389/fcell.2021.716919] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 09/17/2021] [Indexed: 12/20/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that leads to the death of upper and lower motor neurons. While most cases of ALS are sporadic, some of the familial forms of the disease are caused by mutations in the gene encoding for the RNA-binding protein FUS. Under physiological conditions, FUS readily phase separates into liquid-like droplets in vivo and in vitro. ALS-associated mutations interfere with this process and often result in solid-like aggregates rather than fluid condensates. Yet, whether cells recognize and triage aberrant condensates remains poorly understood, posing a major barrier to the development of novel ALS treatments. Using a combination of ALS-associated FUS mutations, optogenetic manipulation of FUS condensation, chemically induced stress, and pH-sensitive reporters of organelle acidity, we systematically characterized the cause-effect relationship between the material state of FUS condensates and the sequestering of lysosomes. From our data, we can derive three conclusions. First, regardless of whether we use wild-type or mutant FUS, expression levels (i.e., high concentrations) play a dominant role in determining the fraction of cells having soluble or aggregated FUS. Second, chemically induced FUS aggregates recruit LAMP1-positive structures. Third, mature, acidic lysosomes accumulate only at FUS aggregates but not at liquid-condensates. Together, our data suggest that lysosome-degradation machinery actively distinguishes between fluid and solid condensates. Unraveling these aberrant interactions and testing strategies to manipulate the autophagosome-lysosome axis provides valuable clues for disease intervention.
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Affiliation(s)
- Franziska Trnka
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Christian Hoffmann
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Han Wang
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Roberto Sansevrino
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Branislava Rankovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Benjamin R Rost
- Laboratory of Network Dysfunction, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
| | - Dietmar Schmitz
- Laboratory of Network Dysfunction, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany.,Berlin Institute of Health, NeuroCure Cluster of Excellence, Charité-UniversitÀtsmedizin Berlin, Corporate Member of Freie UniversitÀt Berlin and Humboldt-UniversitÀt zu Berlin, Berlin, Germany
| | - H Broder Schmidt
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA, United States
| | - Dragomir Milovanovic
- Laboratory of Molecular Neuroscience, German Center for Neurodegenerative Diseases (DZNE), Berlin, Germany
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24
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Wild-type FUS corrects ALS-like disease induced by cytoplasmic mutant FUS through autoregulation. Mol Neurodegener 2021; 16:61. [PMID: 34488813 PMCID: PMC8419956 DOI: 10.1186/s13024-021-00477-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 07/28/2021] [Indexed: 12/04/2022] Open
Abstract
Mutations in FUS, an RNA-binding protein involved in multiple steps of RNA metabolism, are associated with the most severe forms of amyotrophic lateral sclerosis (ALS). Accumulation of cytoplasmic FUS is likely to be a major culprit in the toxicity of FUS mutations. Thus, preventing cytoplasmic mislocalization of the FUS protein may represent a valuable therapeutic strategy. FUS binds to its own pre-mRNA creating an autoregulatory loop efficiently buffering FUS excess through multiple proposed mechanisms including retention of introns 6 and/or 7. Here, we introduced a wild-type FUS gene allele, retaining all intronic sequences, in mice whose heterozygous or homozygous expression of a cytoplasmically retained FUS protein (FusâNLS) was previously shown to provoke ALS-like disease or postnatal lethality, respectively. Wild-type FUS completely rescued the early lethality caused by the two FusâNLS alleles, and improved the age-dependent motor deficits and reduced lifespan caused by heterozygous expression of mutant FUSâNLS. Mechanistically, wild-type FUS decreased the load of cytoplasmic FUS, increased retention of introns 6 and 7 in the endogenous mouse Fus mRNA, and decreased expression of the mutant mRNA. Thus, the wild-type FUS allele activates the homeostatic autoregulatory loop, maintaining constant FUS levels and decreasing the mutant protein in the cytoplasm. These results provide proof of concept that an autoregulatory competent wild-type FUS expression could protect against this devastating, currently intractable, neurodegenerative disease.
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25
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Sternburg EL, Gruijs da Silva LA, Dormann D. Post-translational modifications on RNA-binding proteins: accelerators, brakes, or passengers in neurodegeneration? Trends Biochem Sci 2021; 47:6-22. [PMID: 34366183 DOI: 10.1016/j.tibs.2021.07.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Revised: 07/09/2021] [Accepted: 07/19/2021] [Indexed: 02/07/2023]
Abstract
RNA-binding proteins (RBPs) are critical players in RNA expression and metabolism, thus, the proper regulation of this class of proteins is critical for cellular health. Regulation of RBPs often occurs through post-translational modifications (PTMs), which allow the cell to quickly and efficiently respond to cellular and environmental stimuli. PTMs have recently emerged as important regulators of RBPs implicated in neurodegenerative disorders, in particular amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Here, we summarize how disease-associated PTMs influence the biophysical properties, molecular interactions, subcellular localization, and function of ALS/FTD-linked RBPs, such as FUS and TDP-43. We will discuss how PTMs are believed to play pathological, protective, or ambiguous roles in these neurodegenerative disorders.
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Affiliation(s)
- Erin L Sternburg
- Johannes Gutenberg-UniversitÀt (JGU) Mainz, Faculty of Biology, Mainz, Germany
| | - Lara A Gruijs da Silva
- Johannes Gutenberg-UniversitÀt (JGU) Mainz, Faculty of Biology, Mainz, Germany; Graduate School of Systemic Neurosciences (GSN), Munich, Germany
| | - Dorothee Dormann
- Johannes Gutenberg-UniversitÀt (JGU) Mainz, Faculty of Biology, Mainz, Germany; Institute of Molecular Biology (IMB), Mainz, Germany.
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26
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Abstract
Protein aggregates can sequester RNA in neurodegenerative disease, but the exact RNAs sequestered by tau inclusions have remained uncharacterized. In this issue of Neuron, Lester et al. (2021) begin to identify these RNAs and reveal related perturbations in nuclear speckles.
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