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Mori F, Yasui H, Miki Y, Kon T, Arai A, Kurotaki H, Tomiyama M, Wakabayashi K. Colocalization of TDP-43 and stress granules at the early stage of TDP-43 aggregation in amyotrophic lateral sclerosis. Brain Pathol 2024; 34:e13215. [PMID: 37793650 PMCID: PMC10901621 DOI: 10.1111/bpa.13215] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 09/20/2023] [Indexed: 10/06/2023] Open
Abstract
TDP-43 aggregates (skeins and round inclusions [RIs]) are frequent histopathological features of amyotrophic lateral sclerosis (ALS). We have shown that diffuse punctate cytoplasmic staining (DPCS) is the earliest pathologic manifestation of TDP-43 in ALS, corresponding to nonfibrillar TDP-43 located in the rough endoplasmic reticulum. Previous in vitro studies have suggested that TDP-43 inclusions may be derived from stress granules (SGs). Therefore, we investigated the involvement of SGs in the formation of TDP-43 inclusions. Formalin-fixed spinal cords of six ALS patients with a disease duration of less than 1 year (short duration), eight patients with a disease duration of 2-5 years (standard duration), and five normal controls were subjected to histopathological examination using antibodies against an SG marker, HuR. In normal controls, the cytoplasm of anterior horn cells was diffusely HuR-positive. In short-duration and standard-duration ALS, the number of HuR-positive anterior horn cells was significantly decreased relative to the controls. DPCS and RIs were more frequent in short-duration ALS than in standard-duration ALS. The majority of DPCS areas and a small proportion of RIs, but not skeins, were positive for HuR. Immunoelectron microscopy showed that ribosome-like granular structures in DPCS areas and RIs were labeled with anti-HuR, whereas skeins were not. These findings suggest that colocalization of TDP-43 and SGs occurs at the early stage of TDP-43 aggregation.
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Affiliation(s)
- Fumiaki Mori
- Department of NeuropathologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
| | - Hina Yasui
- Department of NeuropathologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
| | - Yasuo Miki
- Department of NeuropathologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
| | - Tomoya Kon
- Department of NeurologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
| | - Akira Arai
- Department of NeurologyAomori Prefectural Central HospitalAomoriJapan
| | | | - Masahiko Tomiyama
- Department of NeurologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
| | - Koichi Wakabayashi
- Department of NeuropathologyInstitute of Brain Science, Hirosaki University Graduate School of MedicineHirosakiJapan
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2
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Webber CJ, Murphy CN, Rondón-Ortiz AN, van der Spek SJF, Kelly EX, Lampl NM, Chiesa G, Khalil AS, Emili A, Wolozin B. Human herpesvirus 8 ORF57 protein is able to reduce TDP-43 pathology: network analysis identifies interacting pathways. Hum Mol Genet 2023; 32:2966-2980. [PMID: 37522762 PMCID: PMC10549787 DOI: 10.1093/hmg/ddad122] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/01/2023] Open
Abstract
Aggregation of TAR DNA-binding protein 43 kDa (TDP-43) is thought to drive the pathophysiology of amyotrophic lateral sclerosis and some frontotemporal dementias. TDP-43 is normally a nuclear protein that in neurons translocates to the cytoplasm and can form insoluble aggregates upon activation of the integrated stress response (ISR). Viruses evolved to control the ISR. In the case of Herpesvirus 8, the protein ORF57 acts to bind protein kinase R, inhibit phosphorylation of eIF2α and reduce activation of the ISR. We hypothesized that ORF57 might also possess the ability to inhibit aggregation of TDP-43. ORF57 was expressed in the neuronal SH-SY5Y line and its effects on TDP-43 aggregation characterized. We report that ORF57 inhibits TDP-43 aggregation by 55% and elicits a 2.45-fold increase in the rate of dispersion of existing TDP-43 granules. These changes were associated with a 50% decrease in cell death. Proteomic studies were carried out to identify the protein interaction network of ORF57. We observed that ORF57 directly binds to TDP-43 as well as interacts with many components of the ISR, including elements of the proteostasis machinery known to reduce TDP-43 aggregation. We propose that viral proteins designed to inhibit a chronic ISR can be engineered to remove aggregated proteins and dampen a chronic ISR.
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Affiliation(s)
- Chelsea J Webber
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
| | - Caroline N Murphy
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
| | - Alejandro N Rondón-Ortiz
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
- Center for Network Systems Biology, Boston University, Boston, MA 02215, USA
- Department of Biology, Boston University, Boston, MA 02215, USA
| | - Sophie J F van der Spek
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
| | - Elena X Kelly
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
| | - Noah M Lampl
- Center for Network Systems Biology, Boston University, Boston, MA 02215, USA
| | - Giulio Chiesa
- Biological Design Center, Boston University, Boston, MA 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Ahmad S Khalil
- Biological Design Center, Boston University, Boston, MA 02215, USA
- Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Andrew Emili
- Center for Network Systems Biology, Boston University, Boston, MA 02215, USA
- Department of Biochemistry, Boston University, Boston, MA 02115, USA
- Department of Biochemistry, Oregon Health Sciences University, Portland, OR 97239, USA
| | - Benjamin Wolozin
- Departments of Pharmacology, Physiology and Biophysics, Boston University, Boston, MA 02215, USA
- Center for Systems Neuroscience, Boston University, Boston, MA 02115, USA
- Center for Neurophotonics, Boston University, Boston, MA 02115, USA
- Department of Neurology, Boston University, Boston, MA 02115, USA
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3
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Yang C, Qiao T, Yu J, Wang H, Guo Y, Salameh J, Metterville J, Parsi S, Yusuf I, Brown RH, Cai H, Xu Z. Low-level overexpression of wild type TDP-43 causes late-onset, progressive neurodegeneration and paralysis in mice. PLoS One 2022; 17:e0255710. [PMID: 35113871 PMCID: PMC8812852 DOI: 10.1371/journal.pone.0255710] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 01/04/2022] [Indexed: 12/12/2022] Open
Abstract
Modestly increased expression of transactive response DNA binding protein (TDP-43) gene have been reported in amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neuromuscular diseases. However, whether this modest elevation triggers neurodegeneration is not known. Although high levels of TDP-43 overexpression have been modeled in mice and shown to cause early death, models with low-level overexpression that mimic the human condition have not been established. In this study, transgenic mice overexpressing wild type TDP-43 at less than 60% above the endogenous CNS levels were constructed, and their phenotypes analyzed by a variety of techniques, including biochemical, molecular, histological, behavioral techniques and electromyography. The TDP-43 transgene was expressed in neurons, astrocytes, and oligodendrocytes in the cortex and predominantly in astrocytes and oligodendrocytes in the spinal cord. The mice developed a reproducible progressive weakness ending in paralysis in mid-life. Detailed analysis showed ~30% loss of large pyramidal neurons in the layer V motor cortex; in the spinal cord, severe demyelination was accompanied by oligodendrocyte injury, protein aggregation, astrogliosis and microgliosis, and elevation of neuroinflammation. Surprisingly, there was no loss of lower motor neurons in the lumbar spinal cord despite the complete paralysis of the hindlimbs. However, denervation was detected at the neuromuscular junction. These results demonstrate that low-level TDP-43 overexpression can cause diverse aspects of ALS, including late-onset and progressive motor dysfunction, neuroinflammation, and neurodegeneration. Our findings suggest that persistent modest elevations in TDP-43 expression can lead to ALS and other neurological disorders involving TDP-43 proteinopathy. Because of the predictable and progressive clinical paralytic phenotype, this transgenic mouse model will be useful in preclinical trial of therapeutics targeting neurological disorders associated with elevated levels of TDP-43.
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Affiliation(s)
- Chunxing Yang
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Tao Qiao
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jia Yu
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States of America
| | - Hongyan Wang
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Yansu Guo
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Johnny Salameh
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Jake Metterville
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Sepideh Parsi
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Issa Yusuf
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Robert H. Brown
- Department of Neurology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- RNA Therapeutic Institute, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Neuroscience Program, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Huaibin Cai
- Transgenics Section, Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD, United States of America
| | - Zuoshang Xu
- Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- RNA Therapeutic Institute, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Neuroscience Program, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
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4
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Wu S, Du L. Protein Aggregation in the Pathogenesis of Ischemic Stroke. Cell Mol Neurobiol 2021; 41:1183-1194. [PMID: 32529541 DOI: 10.1007/s10571-020-00899-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 06/05/2020] [Indexed: 01/31/2023]
Abstract
Despite the distinction between ischemic stroke and neurodegenerative disorders, they share numerous pathophysiologies particularly those mediated by inflammation and oxidative stress. Although protein aggregation is considered to be a hallmark of neurodegenerative diseases, the formation of protein aggregates can be also induced within a short time after cerebral ischemia, aggravating cerebral ischemic injury. Protein aggregation uncovers a previously unappreciated molecular overlap between neurodegenerative diseases and ischemic stroke. Unfortunately, compared with neurodegenerative disease, mechanism of protein aggregation after cerebral ischemia and how this can be averted remain unclear. This review highlights current understanding on protein aggregation and its intrinsic role in ischemic stroke.
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Affiliation(s)
- Shusheng Wu
- Department of Pharmacology, School of Medicine, Southeast University, Nanjing, 210009, Jiangsu, China.
| | - Longfei Du
- Department of Laboratory Medicine, Affiliated Hospital of Yangzhou University, Yangzhou, Jiangsu, China
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5
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Ishiguro T, Nagai Y, Ishikawa K. Insight Into Spinocerebellar Ataxia Type 31 (SCA31) From Drosophila Model. Front Neurosci 2021; 15:648133. [PMID: 34113230 PMCID: PMC8185138 DOI: 10.3389/fnins.2021.648133] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Spinocerebellar ataxia type 31 (SCA31) is a progressive neurodegenerative disease characterized by degeneration of Purkinje cells in the cerebellum. Its genetic cause is a 2.5- to 3.8-kb-long complex pentanucleotide repeat insertion containing (TGGAA)n, (TAGAA)n, (TAAAA)n, and (TAAAATAGAA)n located in an intron shared by two different genes: brain expressed associated with NEDD4-1 (BEAN1) and thymidine kinase 2 (TK2). Among these repeat sequences, (TGGAA)n repeat was the only sequence segregating with SCA31, which strongly suggests its pathogenicity. In SCA31 patient brains, the mutant BEAN1 transcript containing expanded UGGAA repeats (UGGAAexp) was found to form abnormal RNA structures called RNA foci in cerebellar Purkinje cell nuclei. In addition, the deposition of pentapeptide repeat (PPR) proteins, poly(Trp-Asn-Gly-Met-Glu), translated from UGGAAexp RNA, was detected in the cytoplasm of Purkinje cells. To uncover the pathogenesis of UGGAAexp in SCA31, we generated Drosophila models of SCA31 expressing UGGAAexp RNA. The toxicity of UGGAAexp depended on its length and expression level, which was accompanied by the accumulation of RNA foci and translation of repeat-associated PPR proteins in Drosophila, consistent with the observation in SCA31 patient brains. We also revealed that TDP-43, FUS, and hnRNPA2B1, motor neuron disease–linked RNA-binding proteins bound to UGGAAexp RNA, act as RNA chaperones to regulate the formation of RNA foci and repeat-associated translation. Further research on the role of RNA-binding proteins as RNA chaperones may also provide a novel therapeutic strategy for other microsatellite repeat expansion diseases besides SCA31.
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Affiliation(s)
- Taro Ishiguro
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Bunkyo City, Japan
| | - Yoshitaka Nagai
- Department of Neurotherapeutics, Osaka University Graduate School of Medicine, Suita, Japan
| | - Kinya Ishikawa
- Department of Neurology and Neurological Science, Tokyo Medical and Dental University, Bunkyo City, Japan.,Department of Personalized Genomic Medicine for Health, Graduate School, Tokyo Medical and Dental University, Bunkyo City, Japan
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6
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Ihara K, Sasano T, Hiraoka Y, Togo-Ohno M, Soejima Y, Sawabe M, Tsuchiya M, Ogawa H, Furukawa T, Kuroyanagi H. A missense mutation in the RSRSP stretch of Rbm20 causes dilated cardiomyopathy and atrial fibrillation in mice. Sci Rep 2020; 10:17894. [PMID: 33110103 PMCID: PMC7591520 DOI: 10.1038/s41598-020-74800-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/06/2020] [Indexed: 02/07/2023] Open
Abstract
Dilated cardiomyopathy (DCM) is a fatal heart disease characterized by left ventricular dilatation and cardiac dysfunction. Recent genetic studies on DCM have identified causative mutations in over 60 genes, including RBM20, which encodes a regulator of heart-specific splicing. DCM patients with RBM20 mutations have been reported to present with more severe cardiac phenotypes, including impaired cardiac function, atrial fibrillation (AF), and ventricular arrhythmias leading to sudden cardiac death, compared to those with mutations in the other genes. An RSRSP stretch of RBM20, a hotspot of missense mutations found in patients with idiopathic DCM, functions as a crucial part of its nuclear localization signals. However, the relationship between mutations in the RSRSP stretch and cardiac phenotypes has never been assessed in an animal model. Here, we show that Rbm20 mutant mice harboring a missense mutation S637A in the RSRSP stretch, mimicking that in a DCM patient, demonstrated severe cardiac dysfunction and spontaneous AF and ventricular arrhythmias mimicking the clinical state in patients. In contrast, Rbm20 mutant mice with frame-shifting deletion demonstrated less severe phenotypes, although loss of RBM20-dependent alternative splicing was indistinguishable. RBM20S637A protein cannot be localized to the nuclear speckles, but accumulated in cytoplasmic, perinuclear granule-like structures in cardiomyocytes, which might contribute to the more severe cardiac phenotypes.
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Affiliation(s)
- Kensuke Ihara
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan. .,Department of Cardiovascular Medicine, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan.
| | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Yuichi Hiraoka
- Laboratory of Molecular Neuroscience, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Marina Togo-Ohno
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Yurie Soejima
- Department of Molecular Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Motoji Sawabe
- Department of Molecular Pathology, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Megumi Tsuchiya
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Hidesato Ogawa
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan
| | - Tetsushi Furukawa
- Department of Bio-informational Pharmacology, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan
| | - Hidehito Kuroyanagi
- Laboratory of Gene Expression, Medical Research Institute, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8510, Japan.
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7
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Zhuo XF, Wang J, Zhang J, Jiang LL, Hu HY, Lu JX. Solid-State NMR Reveals the Structural Transformation of the TDP-43 Amyloidogenic Region upon Fibrillation. J Am Chem Soc 2020; 142:3412-3421. [PMID: 32003979 DOI: 10.1021/jacs.9b10736] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
TDP-43 is a primary pathological hallmark protein of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, which may exist in the form of amyloid inclusions in the cells of patients. In addition to serving as a biomarker for these diseases, TDP-43 can also directly trigger neurodegeneration. We previously determined the amyloidogenic core region of TDP-43 (residues 311-360) and showed by solution NMR that this region includes two α-helices [(321-330) and (335-343)] in solution. We suggested that the helix-to-sheet structural transformation initiates TDP-43 aggregation. In the present study, X-ray diffraction shows that TDP-43 (311-360) aggregates adopt a cross-β structure. Thioredoxin (Trx)-fused TDP-43 (311-360) can undergo liquid-liquid phase separation (LLPS) before fibrillation, suggesting that phase separation is an intermediate step before amyloid formation. Solid-state NMR (SSNMR), carried out to elucidate the structural changes of TDP-43 (311-360) at the atomic level, indicates five β-strands of the amyloids formed, with the major two β-strands contributed by the first helical region in the solution structure. The NMR evidence is also in support of the fibril having a parallel in-register conformation, implying a mechanism in which the helix-helix interactions in LLPS are converted into β-strand parallel lateral association upon fibrillation. Our studies have assigned many key interresidue interactions that contribute to the stability of the fibril, including F316 with I318 and Q327 and W334 with A325, A326, A329, and S332. SSNMR with 1H detection reveals a unique close interaction between the indole Nε1-Hε1 of W334 and the side-chain carbonyl of Q343. This interaction could be a very important factor in initiating TDP-43 (311-360) folding/misfolding in LLPS.
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Affiliation(s)
- Xiao-Feng Zhuo
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China.,State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Jian Wang
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China
| | - Jing Zhang
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China.,State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China.,University of Chinese Academy of Sciences , Beijing 100049 , People's Republic of China
| | - Lei-Lei Jiang
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China
| | - Hong-Yu Hu
- State Key Laboratory of Molecular Biology, CAS Center for Excellence in Molecular Cell Science , Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences , Shanghai 200031 , People's Republic of China
| | - Jun-Xia Lu
- School of Life Science and Technology , ShanghaiTech University , Shanghai 201210 , People's Republic of China
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8
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Hans F, Glasebach H, Kahle PJ. Multiple distinct pathways lead to hyperubiquitylated insoluble TDP-43 protein independent of its translocation into stress granules. J Biol Chem 2020. [DOI: 10.1016/s0021-9258(17)49926-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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9
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Hans F, Glasebach H, Kahle PJ. Multiple distinct pathways lead to hyperubiquitylated insoluble TDP-43 protein independent of its translocation into stress granules. J Biol Chem 2019; 295:673-689. [PMID: 31780563 DOI: 10.1074/jbc.ra119.010617] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 11/15/2019] [Indexed: 12/14/2022] Open
Abstract
Insoluble, hyperubiquitylated TAR DNA-binding protein of 43 kDa (TDP-43) in the central nervous system characterizes frontotemporal dementia and ALS in many individuals with these neurodegenerative diseases. The causes for neuropathological TDP-43 aggregation are unknown, but it has been suggested that stress granule (SG) formation is important in this process. Indeed, in human embryonic kidney HEK293E cells, various SG-forming conditions induced very strong TDP-43 ubiquitylation, insolubility, and reduced splicing activity. Osmotic stress-induced SG formation and TDP-43 ubiquitylation occurred rapidly and coincided with colocalization of TDP-43 and SG markers. Washout experiments confirmed the rapid dissolution of SGs, accompanied by normalization of TDP-43 ubiquitylation and solubility. Surprisingly, interference with the SG process using a protein kinase R-like endoplasmic reticulum kinase inhibitor (GSK2606414) or the translation blocker emetine did not prevent TDP-43 ubiquitylation and insolubility. Thus, parallel pathways may lead to pathological TDP-43 modifications independent of SG formation. Using a panel of kinase inhibitors targeting signaling pathways of the osmotic shock inducer sorbitol, we could largely rule out the stress-activated and extracellular signal-regulated protein kinase modules and glycogen synthase kinase 3β. For arsenite, but not for sorbitol, quenching oxidative stress with N-acetylcysteine did suppress both SG formation and TDP-43 ubiquitylation and insolubility. Thus, sodium arsenite appears to promote SG formation and TDP-43 modifications via oxidative stress, but sorbitol stimulates TDP-43 ubiquitylation and insolubility via a novel pathway(s) independent of SG formation. In conclusion, pathological TDP-43 modifications can be mediated via multiple distinct pathways for which SGs are not essential.
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Affiliation(s)
- Friederike Hans
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany
| | - Hanna Glasebach
- Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, University of Tübingen, 72076 Tübingen, Germany
| | - Philipp J Kahle
- German Center for Neurodegenerative Diseases (DZNE), 72076 Tübingen, Germany .,Hertie Institute for Clinical Brain Research, Department of Neurodegeneration, University of Tübingen, 72076 Tübingen, Germany
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10
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Abstract
Recent advances suggest that the response of RNA metabolism to stress has an important role in the pathophysiology of neurodegenerative diseases, particularly amyotrophic lateral sclerosis, frontotemporal dementias and Alzheimer disease. RNA-binding proteins (RBPs) control the utilization of mRNA during stress, in part through the formation of membraneless organelles termed stress granules (SGs). These structures form through a process of liquid-liquid phase separation. Multiple biochemical pathways regulate SG biology. The major signalling pathways regulating SG formation include the mammalian target of rapamycin (mTOR)-eukaryotic translation initiation factor 4F (eIF4F) and eIF2α pathways, whereas the pathways regulating SG dispersion and removal are mediated by valosin-containing protein and the autolysosomal cascade. Post-translational modifications of RBPs also strongly contribute to the regulation of SGs. Evidence indicates that SGs are supposed to be transient structures, but the chronic stresses associated with ageing lead to chronic, persistent SGs that appear to act as a nidus for the aggregation of disease-related proteins. We suggest a model describing how intrinsic vulnerabilities within the cellular RNA metabolism might lead to the pathological aggregation of RBPs when SGs become persistent. This process might accelerate the pathophysiology of many neurodegenerative diseases and myopathies, and it suggests new targets for disease intervention.
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Affiliation(s)
- Benjamin Wolozin
- Department of Pharmacology, Boston University School of Medicine, Boston, MA, USA.
- Department of Neurology, Boston University School of Medicine, Boston, MA, USA.
| | - Pavel Ivanov
- Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Boston, MA, USA
- Department of Medicine, Harvard Medical School, Boston, MA, USA
- The Broad Institute of Harvard and MIT, Cambridge, MA, USA
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11
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Kawakami I, Arai T, Hasegawa M. The basis of clinicopathological heterogeneity in TDP-43 proteinopathy. Acta Neuropathol 2019; 138:751-770. [PMID: 31555895 PMCID: PMC6800885 DOI: 10.1007/s00401-019-02077-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 08/27/2019] [Accepted: 09/13/2019] [Indexed: 12/15/2022]
Abstract
Transactive response DNA-binding protein 43 kDa (TDP-43) was identified as a major disease-associated component in the brain of patients with amyotrophic lateral sclerosis (ALS), as well as the largest subset of patients with frontotemporal lobar degeneration with ubiquitinated inclusions (FTLD-U), which characteristically exhibits cytoplasmic inclusions that are positive for ubiquitin but negative for tau and α-synuclein. TDP-43 pathology occurs in distinct brain regions, involves disparate brain networks, and features accumulation of misfolded proteins in various cell types and in different neuroanatomical regions. The clinical phenotypes of ALS and FTLD-TDP (FTLD with abnormal intracellular accumulations of TDP-43) correlate with characteristic distribution patterns of the underlying pathology across specific brain regions with disease progression. Recent studies support the idea that pathological protein spreads from neuron to neuron via axonal transport in a hierarchical manner. However, little is known to date about the basis of the selective cellular and regional vulnerability, although the information would have important implications for the development of targeted and personalized therapies. Here, we aim to summarize recent advances in the neuropathology, genetics and animal models of TDP-43 proteinopathy, and their relationship to clinical phenotypes for the underlying selective neuronal and regional susceptibilities. Finally, we attempt to integrate these findings into the emerging picture of TDP-43 proteinopathy, and to highlight key issues for future therapy and research.
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Affiliation(s)
- Ito Kawakami
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
- Department of Neuropathology, Tokyo Metropolitan Geriatric Hospital and Institute, Tokyo, Japan
| | - Tetsuaki Arai
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.
- Department of Psychiatry, Division of Clinical Medicine, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan.
| | - Masato Hasegawa
- Dementia Research Project, Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan.
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