1
|
Koike Y. Abnormal Splicing Events due to Loss of Nuclear Function of TDP-43: Pathophysiology and Perspectives. JMA J 2024; 7:313-318. [PMID: 39114608 PMCID: PMC11301021 DOI: 10.31662/jmaj.2024-0038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Accepted: 03/14/2024] [Indexed: 08/10/2024] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are neurodegenerative diseases with a progressive and fatal course. They are often comorbid and share the same molecular spectrum. Their key pathological features are the formation of the aggregation of TDP-43, an RNA-binding protein, in the cytoplasm and its depletion from the nucleus in the central nervous system. In the nucleus, TDP-43 regulates several aspects of RNA metabolism, ranging from RNA transcription and alternative splicing to RNA transport. Suppressing the aberrant splicing events during RNA processing is one of the significant functions of TDP-43. This function is impaired when TDP-43 becomes depleted from the nucleus. Several critical cryptic splicing targets of TDP-43 have recently emerged, such as STMN2, UNC13A, and others. UNC13A is an important ALS/FTD risk gene, and the genetic variations, single nucleotide polymorphisms, cause disease via the increased susceptibility for cryptic exon inclusion under the TDP-43 dysfunction. Moreover, TDP-43 has an autoregulatory mechanism that regulates the splicing of its mRNA (TARDBP mRNA) in the healthy state. This study provides recent findings on the splicing regulatory function of TDP-43 and discusses the prospects of using these aberrant splicing events as efficient biomarkers.
Collapse
Affiliation(s)
- Yuka Koike
- Department of Molecular Neuroscience, Brain Research Institute, Niigata University, Niigata, Japan
- Department of Neuroscience, Mayo Clinic Florida, Florida, USA
| |
Collapse
|
2
|
Koike Y. Molecular mechanisms linking loss of TDP-43 function to amyotrophic lateral sclerosis/frontotemporal dementia-related genes. Neurosci Res 2024:S0168-0102(24)00063-4. [PMID: 38723906 DOI: 10.1016/j.neures.2024.05.001] [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: 03/08/2024] [Revised: 04/18/2024] [Accepted: 05/01/2024] [Indexed: 05/13/2024]
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are characterized by nuclear depletion and cytoplasmic aggregation of TAR DNA-binding protein-43 (TDP-43). TDP-43 plays a key role in regulating the splicing of numerous genes, including TARDBP. This review aims to delineate two aspects of ALS/FTD pathogenesis associated with TDP-43 function. First, we provide novel mechanistic insights into the splicing of UNC13A, a TDP-43 target gene. Single nucleotide polymorphisms (SNPs) in UNC13A are the most common risk factors for ALS/FTD. We found that TDP-43 represses "cryptic exon" inclusion during UNC13A RNA splicing. A risk-associated SNP in this exon results in increased RNA levels of UNC13A retaining the cryptic exon. Second, we described the perturbation of the TDP-43 autoregulatory mechanism caused by age-related DNA demethylation. Aging is a major risk factor for sporadic ALS/FTD. Typically, TDP-43 levels are regulated via alternative splicing of TARDBP mRNA. We hypothesized that TARDBP methylation is altered by aging, thereby disrupting TDP-43 autoregulation. We found that demethylation reduces the efficiency of alternative splicing and increases TARDBP mRNA levels. Moreover, we demonstrated that, with aging, this region is demethylated in the human motor cortex and is associated with the early onset of ALS.
Collapse
Affiliation(s)
- Yuka Koike
- Department of Molecular Neuroscience, Brain Research Institute, Niigata University, Japan.
| |
Collapse
|
3
|
Gimenez J, Spalloni A, Cappelli S, Ciaiola F, Orlando V, Buratti E, Longone P. TDP-43 Epigenetic Facets and Their Neurodegenerative Implications. Int J Mol Sci 2023; 24:13807. [PMID: 37762112 PMCID: PMC10530927 DOI: 10.3390/ijms241813807] [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: 07/06/2023] [Revised: 07/31/2023] [Accepted: 08/09/2023] [Indexed: 09/29/2023] Open
Abstract
Since its initial involvement in numerous neurodegenerative pathologies in 2006, either as a principal actor or as a cofactor, new pathologies implicating transactive response (TAR) DNA-binding protein 43 (TDP-43) are regularly emerging also beyond the neuronal system. This reflects the fact that TDP-43 functions are particularly complex and broad in a great variety of human cells. In neurodegenerative diseases, this protein is often pathologically delocalized to the cytoplasm, where it irreversibly aggregates and is subjected to various post-translational modifications such as phosphorylation, polyubiquitination, and cleavage. Until a few years ago, the research emphasis has been focused particularly on the impacts of this aggregation and/or on its widely described role in complex RNA splicing, whether related to loss- or gain-of-function mechanisms. Interestingly, recent studies have strengthened the knowledge of TDP-43 activity at the chromatin level and its implication in the regulation of DNA transcription and stability. These discoveries have highlighted new features regarding its own transcriptional regulation and suggested additional mechanistic and disease models for the effects of TPD-43. In this review, we aim to give a comprehensive view of the potential epigenetic (de)regulations driven by (and driving) this multitask DNA/RNA-binding protein.
Collapse
Affiliation(s)
- Juliette Gimenez
- Molecular Neurobiology Laboratory, Experimental Neuroscience, IRCCS Fondazione Santa Lucia (FSL), 00143 Rome, Italy; (A.S.); (P.L.)
| | - Alida Spalloni
- Molecular Neurobiology Laboratory, Experimental Neuroscience, IRCCS Fondazione Santa Lucia (FSL), 00143 Rome, Italy; (A.S.); (P.L.)
| | - Sara Cappelli
- Molecular Pathology Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy; (S.C.); (E.B.)
| | - Francesca Ciaiola
- Molecular Neurobiology Laboratory, Experimental Neuroscience, IRCCS Fondazione Santa Lucia (FSL), 00143 Rome, Italy; (A.S.); (P.L.)
- Department of Systems Medicine, University of Roma Tor Vergata, 00133 Rome, Italy
| | - Valerio Orlando
- KAUST Environmental Epigenetics Program, Biological Environmental Sciences and Engineering Division BESE, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia;
| | - Emanuele Buratti
- Molecular Pathology Laboratory, International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy; (S.C.); (E.B.)
| | - Patrizia Longone
- Molecular Neurobiology Laboratory, Experimental Neuroscience, IRCCS Fondazione Santa Lucia (FSL), 00143 Rome, Italy; (A.S.); (P.L.)
| |
Collapse
|
4
|
Sato T, Oda K, Sakai S, Kato R, Yamamori S, Itakura M, Kodera Y, Nishizawa M, Sasaoka T, Onodera O, Yokoyama M. Importance of the Q/N-rich segment for protein stability of endogenous mouse TDP-43. Sci Rep 2022; 12:14923. [PMID: 36056157 PMCID: PMC9440050 DOI: 10.1038/s41598-022-19153-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 08/24/2022] [Indexed: 11/09/2022] Open
Abstract
TAR DNA-binding protein 43 kDa (TDP-43), a nuclear protein, plays an important role in the molecular pathogenesis of amyotrophic lateral sclerosis (ALS). The long-disordered C-terminal region (CTR) of TDP-43 is known to be aggregation-prone and a hotspot for ALS mutations, so elucidation of the physiological function of CTR will provide insights into the pathogenesis of ALS. The CTR has two Gly, aromatic, and Ser-rich (GaroS) segments and an amyloidogenic core divided into a hydrophobic patch (HP) and a Gln/Asn (Q/N)-rich segment. Although TDP-43 lacking the CTR is known to be unstable, as observed in knock-in mice, it is unclear which of these segments contributes to the stability of TDP-43. Here, we generated 12 mouse lines lacking the various sub-regions of CTR by genome editing and compared the embryonic lethality of homozygotes, and protein and mRNA expression levels of TDP-43. We demonstrated the functional diversity of the four segments of CTR, finding that the presence of the Q/N-rich segment greatly restored the protein stability of TDP-43. In addition, we found that the second GaroS deletion did not affect protein stability and mouse development.
Collapse
Affiliation(s)
- Toshiya Sato
- Department of Laboratory Animal Science, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan. .,Center for Genetic Studies of Integrated Biological Functions, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan. .,Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.
| | - Kanako Oda
- Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Seiko Sakai
- Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Rika Kato
- Center for Genetic Studies of Integrated Biological Functions, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Saori Yamamori
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Makoto Itakura
- Department of Biochemistry, Kitasato University School of Medicine, Sagamihara, 252-0374, Japan
| | - Yoshio Kodera
- Department of Physics, Kitasato University School of Science, Sagamihara, 252-0373, Japan
| | - Masatoyo Nishizawa
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.,Department of Nursing, Niigata University of Health and Welfare, Niigata, 950-3198, Japan
| | - Toshikuni Sasaoka
- Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Osamu Onodera
- Department of Neurology, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan
| | - Minesuke Yokoyama
- Department of Comparative and Experimental Medicine, Brain Research Institute, Niigata University, Niigata, 951-8585, Japan.,Central Institute for Experimental Animals, Kawasaki, 210-0821, Japan
| |
Collapse
|
5
|
Age-related demethylation of the TDP-43 autoregulatory region in the human motor cortex. Commun Biol 2021; 4:1107. [PMID: 34548609 PMCID: PMC8455575 DOI: 10.1038/s42003-021-02621-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 09/01/2021] [Indexed: 11/21/2022] Open
Abstract
In amyotrophic lateral sclerosis (ALS), TAR DNA-binding protein 43 (TDP-43), which is encoded by TARDBP, forms aggregates in the motor cortex. This aggregate formation may be triggered by an increase in the TDP-43 level with aging. However, the amount of TDP-43 is autoregulated by alternative splicing of the TARDBP 3′UTR, and how this autoregulation is affected by aging remains to be elucidated. We found that DNA demethylation in the autoregulatory region in the TARDBP 3′UTR reduced alternative splicing and increased TARDBP mRNA expression. Furthermore, in the human motor cortex, we found that this region was demethylated with aging, resulting in increased expression of TARDBP mRNA. The acceleration of DNA demethylation in the motor cortex was associated with the age of ALS onset. In summary, the dysregulation of TDP-43 autoregulation by age-related DNA demethylation in the motor cortex may explain the contribution of aging and motor system selectivity in ALS. In order to assess the effects of aging on the autoregulation of TAR DNA-binding protein 43 (TDP-43) and the potential effects of this on the role of TDP-43 in Amyotrophic Lateral Sclerosis (ALS), Koike et al examined post-mortem motor cortex tissue from ALS patients. They found that DNA demethylation in the autoregulatory region of the TARDBP 3′UTR, which encodes TDP-43, increased with age and was associated with the onset age of ALS and thus could be indicative of a role for dysregulation of TDP-43 autoregulation in ALS pathology.
Collapse
|
6
|
Root J, Merino P, Nuckols A, Johnson M, Kukar T. Lysosome dysfunction as a cause of neurodegenerative diseases: Lessons from frontotemporal dementia and amyotrophic lateral sclerosis. Neurobiol Dis 2021; 154:105360. [PMID: 33812000 PMCID: PMC8113138 DOI: 10.1016/j.nbd.2021.105360] [Citation(s) in RCA: 91] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 03/16/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022] Open
Abstract
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are fatal neurodegenerative disorders that are thought to exist on a clinical and pathological spectrum. FTD and ALS are linked by shared genetic causes (e.g. C9orf72 hexanucleotide repeat expansions) and neuropathology, such as inclusions of ubiquitinated, misfolded proteins (e.g. TAR DNA-binding protein 43; TDP-43) in the CNS. Furthermore, some genes that cause FTD or ALS when mutated encode proteins that localize to the lysosome or modulate endosome-lysosome function, including lysosomal fusion, cargo trafficking, lysosomal acidification, autophagy, or TFEB activity. In this review, we summarize evidence that lysosomal dysfunction, caused by genetic mutations (e.g. C9orf72, GRN, MAPT, TMEM106B) or toxic-gain of function (e.g. aggregation of TDP-43 or tau), is an important pathogenic disease mechanism in FTD and ALS. Further studies into the normal function of many of these proteins are required and will help uncover the mechanisms that cause lysosomal dysfunction in FTD and ALS. Mutations or polymorphisms in genes that encode proteins important for endosome-lysosome function also occur in other age-dependent neurodegenerative diseases, including Alzheimer's (e.g. APOE, PSEN1, APP) and Parkinson's (e.g. GBA, LRRK2, ATP13A2) disease. A more complete understanding of the common and unique features of lysosome dysfunction across the spectrum of neurodegeneration will help guide the development of therapies for these devastating diseases.
Collapse
Affiliation(s)
- Jessica Root
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Paola Merino
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Austin Nuckols
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Michelle Johnson
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia
| | - Thomas Kukar
- Department of Pharmacology and Chemical Biology, Emory University, School of Medicine, Atlanta 30322, Georgia; Center for Neurodegenerative Disease, Emory University, School of Medicine, Atlanta 30322, Georgia; Department of Neurology, Emory University, School of Medicine, Atlanta 30322, Georgia.
| |
Collapse
|
7
|
Baralle M, Romano M. Characterization of the human TARDBP gene promoter. Sci Rep 2021; 11:10438. [PMID: 34002018 PMCID: PMC8129075 DOI: 10.1038/s41598-021-89973-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Accepted: 05/04/2021] [Indexed: 02/03/2023] Open
Abstract
The expression of TDP-43, the main component of neuronal intracellular inclusions across a broad spectrum of ALS and FTD disorders, is developmentally regulated and studies in vivo have shown that TDP-43 overexpression can be toxic, even before observation of pathological aggregates. Starting from these observations, the regulation of its expression at transcriptional level might represent a further key element for the pathogenesis of neurodegenerative diseases. Therefore, we have characterized the human TARDBP promoter, in order to study the transcriptional mechanisms of expression. Mapping of cis-acting elements by luciferase assays in different cell outlined that the activity of the promoter seems to be higher in SH-SY5Y, Neuro2A, and HeLa than in HEK293. In addition, we tested effects of two SNPs found in the promoter region of ALS patients and observed no significant effect on transcription levels in all tested cell lines. Lastly, while TDP-43 overexpression did not affect significantly the activity of its promoter (suggesting that TDP-43 does not influence its own transcription), the presence of the 5'UTR sequence and of intron-1 splicing seem to impact positively on TDP-43 expression without affecting transcript stability. In conclusion, we have identified the region spanning nucleotides 451-230 upstream from the transcription start site as the minimal region with a significant transcription activity. These results lay an important foundation for exploring the regulation of the TARDBP gene transcription by exogenous and endogenous stimuli and the implication of transcriptional mechanisms in the pathogenesis of TDP-43 proteinopathies.
Collapse
Affiliation(s)
- Marco Baralle
- grid.425196.d0000 0004 1759 4810International Centre for Genetic Engineering and Biotechnology (ICGEB), Area Science Park, Padriciano, Trieste, Italy
| | - Maurizio Romano
- grid.5133.40000 0001 1941 4308Department of Life Sciences, University of Trieste, Via A. Valerio 28, 34127 Trieste, Italy
| |
Collapse
|
8
|
Wood A, Gurfinkel Y, Polain N, Lamont W, Lyn Rea S. Molecular Mechanisms Underlying TDP-43 Pathology in Cellular and Animal Models of ALS and FTLD. Int J Mol Sci 2021; 22:4705. [PMID: 33946763 PMCID: PMC8125728 DOI: 10.3390/ijms22094705] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/22/2021] [Accepted: 04/28/2021] [Indexed: 02/03/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are neurodegenerative disorders that exist on a disease spectrum due to pathological, clinical and genetic overlap. In up to 97% of ALS cases and ~50% of FTLD cases, the primary pathological protein observed in affected tissues is TDP-43, which is hyperphosphorylated, ubiquitinated and cleaved. The TDP-43 is observed in aggregates that are abnormally located in the cytoplasm. The pathogenicity of TDP-43 cytoplasmic aggregates may be linked with both a loss of nuclear function and a gain of toxic functions. The cellular processes involved in ALS and FTLD disease pathogenesis include changes to RNA splicing, abnormal stress granules, mitochondrial dysfunction, impairments to axonal transport and autophagy, abnormal neuromuscular junctions, endoplasmic reticulum stress and the subsequent induction of the unfolded protein response. Here, we review and discuss the evidence for alterations to these processes that have been reported in cellular and animal models of TDP-43 proteinopathy.
Collapse
Affiliation(s)
- Alistair Wood
- School of Molecular Science, University of Western Australia, Nedlands 6009, Australia;
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch 6150, Australia; (Y.G.); (N.P.)
| | - Yuval Gurfinkel
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch 6150, Australia; (Y.G.); (N.P.)
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Nedlands 6009, Australia;
| | - Nicole Polain
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch 6150, Australia; (Y.G.); (N.P.)
| | - Wesley Lamont
- Perron Institute for Neurological and Translational Science, Centre for Neuromuscular and Neurological Disorders, University of Western Australia, Nedlands 6009, Australia;
| | - Sarah Lyn Rea
- Centre for Molecular Medicine and Innovative Therapeutics, Murdoch University, Health Research Building, Discovery Way, Murdoch 6150, Australia; (Y.G.); (N.P.)
- Hub for Immersive Visualisation and eResearch, Curtin University, Bentley 6102, Australia
- Harry Perkins Institute of Medical Research, Centre for Medical Research, University of Western Australia, Nedlands 6009, Australia
| |
Collapse
|
9
|
Bitetto G, Di Fonzo A. Nucleo-cytoplasmic transport defects and protein aggregates in neurodegeneration. Transl Neurodegener 2020; 9:25. [PMID: 32616075 PMCID: PMC7333321 DOI: 10.1186/s40035-020-00205-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 06/01/2020] [Indexed: 02/06/2023] Open
Abstract
In the ongoing process of uncovering molecular abnormalities in neurodegenerative diseases characterized by toxic protein aggregates, nucleo-cytoplasmic transport defects have an emerging role. Several pieces of evidence suggest a link between neuronal protein inclusions and nuclear pore complex (NPC) damage. These processes lead to oxidative stress, inefficient transcription, and aberrant DNA/RNA maintenance. The clinical and neuropathological spectrum of NPC defects is broad, ranging from physiological aging to a suite of neurodegenerative diseases. A better understanding of the shared pathways among these conditions may represent a significant step toward dissecting their underlying molecular mechanisms, opening the way to a real possibility of identifying common therapeutic targets.
Collapse
Affiliation(s)
- Giacomo Bitetto
- IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy
| | - Alessio Di Fonzo
- IRCCS Foundation Ca' Granda Ospedale Maggiore Policlinico, Dino Ferrari Center, Neuroscience Section, Department of Pathophysiology and Transplantation, University of Milan, Via Francesco Sforza 35, 20122, Milan, Italy.
| |
Collapse
|
10
|
Pham J, Keon M, Brennan S, Saksena N. Connecting RNA-Modifying Similarities of TDP-43, FUS, and SOD1 with MicroRNA Dysregulation Amidst A Renewed Network Perspective of Amyotrophic Lateral Sclerosis Proteinopathy. Int J Mol Sci 2020; 21:ijms21103464. [PMID: 32422969 PMCID: PMC7278980 DOI: 10.3390/ijms21103464] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 05/10/2020] [Accepted: 05/11/2020] [Indexed: 12/11/2022] Open
Abstract
Beyond traditional approaches in understanding amyotrophic lateral sclerosis (ALS), multiple recent studies in RNA-binding proteins (RBPs)-including transactive response DNA-binding protein (TDP-43) and fused in sarcoma (FUS)-have instigated an interest in their function and prion-like properties. Given their prominence as hallmarks of a highly heterogeneous disease, this prompts a re-examination of the specific functional interrelationships between these proteins, especially as pathological SOD1-a non-RBP commonly associated with familial ALS (fALS)-exhibits similar properties to these RBPs including potential RNA-regulatory capabilities. Moreover, the cytoplasmic mislocalization, aggregation, and co-aggregation of TDP-43, FUS, and SOD1 can be identified as proteinopathies akin to other neurodegenerative diseases (NDs), eliciting strong ties to disrupted RNA splicing, transport, and stability. In recent years, microRNAs (miRNAs) have also been increasingly implicated in the disease, and are of greater significance as they are the master regulators of RNA metabolism in disease pathology. However, little is known about the role of these proteins and how they are regulated by miRNA, which would provide mechanistic insights into ALS pathogenesis. This review seeks to discuss current developments across TDP-43, FUS, and SOD1 to build a detailed snapshot of the network pathophysiology underlying ALS while aiming to highlight possible novel therapeutic targets to guide future research.
Collapse
Affiliation(s)
- Jade Pham
- Faculty of Medicine, The University of New South Wales, Kensington, Sydney, NSW 2033, Australia;
| | - Matt Keon
- Iggy Get Out, Neurodegenerative Disease Section, Darlinghurst, Sydney, NSW 2010, Australia; (M.K.); (S.B.)
| | - Samuel Brennan
- Iggy Get Out, Neurodegenerative Disease Section, Darlinghurst, Sydney, NSW 2010, Australia; (M.K.); (S.B.)
| | - Nitin Saksena
- Iggy Get Out, Neurodegenerative Disease Section, Darlinghurst, Sydney, NSW 2010, Australia; (M.K.); (S.B.)
- Correspondence:
| |
Collapse
|
11
|
Kasahara S, Ishihara T, Koike Y, Sugai A, Onodera O. [Molecular mechanism of amyotrophic lateral sclerosis (ALS) from the viewpoint of the formation and degeneration of transactive response DNA-binding protein 43 kDa (TDP-43) inclusions]. Rinsho Shinkeigaku 2020; 60:109-116. [PMID: 31956195 DOI: 10.5692/clinicalneurol.cn-001362] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Sporadic amyotrophic lateral sclerosis (SALS) and many cases of familial ALS (FALS) demonstrate cytoplasmic transactive response DNA-binding protein 43 kDa (TDP-43)-positive inclusion bodies. Thus, TDP-43 plays a vital role in ALS pathogenesis. Functional analysis of the ALS causative genes advanced the elucidation of the mechanism associated with the formation and degradation of TDP-43 aggregates. Stress granules, which are non-membranous organelles, are attracting attention as sites of aggregate formation, with involvement of FUS and C9orf72. Concurrently, ALS causative genes related to the ubiquitin-proteasome and autophagy systems, which are aggregate degradation mechanisms, have also been reported. Therefore, therapeutic research based on the molecular pathology common to SALS and FALS has been advanced.
Collapse
Affiliation(s)
- Sou Kasahara
- Department of Neurology, Brain Research Institute, Niigata University
| | - Tomohiko Ishihara
- Department of Neurology, Brain Research Institute, Niigata University
| | - Yuka Koike
- Department of Neurology, Brain Research Institute, Niigata University
| | - Akihiro Sugai
- Department of Neurology, Brain Research Institute, Niigata University
| | - Osamu Onodera
- Department of Neurology, Brain Research Institute, Niigata University
| |
Collapse
|
12
|
Sugai A, Kato T, Koyama A, Koike Y, Konno T, Ishihara T, Onodera O. Non-genetically modified models exhibit TARDBP mRNA increase due to perturbed TDP-43 autoregulation. Neurobiol Dis 2019; 130:104534. [PMID: 31310801 DOI: 10.1016/j.nbd.2019.104534] [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: 10/18/2018] [Revised: 06/22/2019] [Accepted: 07/12/2019] [Indexed: 12/12/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by accumulation of fragmented insoluble TDP-43 and loss of TDP-43 from the nucleus. Increased expression of exogenous TARDBP (encoding TDP-43) induces TDP-43 pathology and cytotoxicity, suggesting the involvement of aberrant expression of TDP-43 in the pathogenesis of ALS. In normal conditions, however, the amount of TDP-43 is tightly regulated by the autoregulatory mechanism involving alternative splicing of TARDBP mRNA. To investigate the influence of autoregulation dysfunction, we inhibited the splicing of cryptic intron 6 using antisense oligonucleotides in vivo. This inhibition doubled the Tardbp mRNA expression, increased the fragmented insoluble TDP-43, and reduced the number of motor neurons in the mouse spinal cord. In human induced pluripotent stem cell-derived neurons, the splicing inhibition of intron 6 increased TARDBP mRNA and decreased nuclear TDP-43. These non-genetically modified models exhibiting rise in the TARDBP mRNA levels suggest that TDP-43 autoregulation turbulence might be linked to the pathogenesis of ALS.
Collapse
Affiliation(s)
- Akihiro Sugai
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Taisuke Kato
- Department of System Pathology for Neurological Disorders, Brain Science Branch, Center for Bioresource-based Research, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Akihide Koyama
- Division of Legal Medicine, Graduate School of Medicine and Dental Science, Niigata University, Niigata 951-8585, Japan
| | - Yuka Koike
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Takuya Konno
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Tomohiko Ishihara
- Department of Molecular Neuroscience, Resource Branch for Brain Disease Research, Center for Bioresource-based Research, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Osamu Onodera
- Department of Neurology, Clinical Neuroscience Branch, Brain Research Institute, Niigata University, Niigata 951-8585, Japan.
| |
Collapse
|
13
|
Mutant TDP-43 Causes Early-Stage Dose-Dependent Motor Neuron Degeneration in a TARDBP Knockin Mouse Model of ALS. Cell Rep 2019; 26:364-373.e4. [DOI: 10.1016/j.celrep.2018.12.045] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 08/16/2018] [Accepted: 12/11/2018] [Indexed: 12/12/2022] Open
|