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Tan RH, McCann H, Shepherd CE, Pinkerton M, Mazumder S, Devenney EM, Adler GL, Rowe DB, Kril J, Halliday GM, Kiernan MC. Heterogeneity of cortical pTDP-43 inclusion morphologies in amyotrophic lateral sclerosis. Acta Neuropathol Commun 2023; 11:180. [PMID: 37957721 PMCID: PMC10642010 DOI: 10.1186/s40478-023-01670-2] [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: 07/05/2023] [Accepted: 10/10/2023] [Indexed: 11/15/2023] Open
Abstract
BACKGROUND Despite the presence of significant cortical pTDP-43 inclusions of heterogeneous morphologies in patients diagnosed with amyotrophic lateral sclerosis (ALS), pathological subclassification is routinely performed in the minority of patients with concomitant frontotemporal dementia (FTD). OBJECTIVE In order to improve current understanding of the presence and relevance of pathological pTDP-43 subtypes in ALS, the present study examined the pattern of cortical pTDP-43 aggregates in 61 ALS cases without FTD. RESULTS Based on the presence, morphology and composition of pTDP-43 pathology, three distinct ALS-TDP subtypes were delineated: (1) A predominant pattern of pTDP-43 granulofilamentous neuronal inclusions (GFNIs) and grains that were immuno-negative for p62 was identified in 18% of cases designated ALS-TDP type E; (2) neuronal cytoplasmic inclusions (NCIs) that were immuno-positive for both pTDP-43 and p62 were observed in 67% of cases assigned ALS-TDP type B; and (3) scarce cortical pTDP-43 and p62 aggregates were identified in 15% of cases coined ALS-TDP type SC (scarce cortical). Quantitative analyses revealed a significantly greater burden of pTDP-43 GFNI and grains in ALS-TDP type E. Principal component analysis demonstrated significant relationships between GFNIs, grains and ALS-TDP subtypes to support the distinction of subtypes E and B. No significant difference in age at death or disease duration was found between ALS-TDP subgroups to suggest that these subtypes represent earlier or later stages of the same disease process. Instead, a significantly higher ALS-TDP stage, indicating greater topographical spread of pTDP-43, was identified in ALS-TDP type E. Alzheimer's disease neuropathological change (ABC score ≥ intermediate) and Lewy body disease (Braak stage ≥ IV) was more prevalent in the ALS-TDP type SC cohort, which also demonstrated a significantly lower overall cognitive score. CONCLUSION In summary, the present study demonstrates that ALS-TDP does not represent a single homogenous neuropathology. We propose the subclassification of ALS-TDP into three distinct subtypes using standard immuno-stains for pTDP-43 and p62 in the motor cortex, which is routinely sampled and evaluated for diagnostic neuropathological characterisation of ALS. We propose that future studies specify both clinicopathological group and pTDP-43 subtype to advance current understanding of the pathogenesis of clinical phenotypes in pTDP-43 proteinopathies, which will have significant relevance to the development of targeted therapies for this heterogeneous disorder.
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Affiliation(s)
- Rachel H Tan
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia.
- Faculty of Medicine and Health, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia.
| | - Heather McCann
- Neuroscience Research Australia, Randwick, NSW, Australia
| | | | - Monica Pinkerton
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Srestha Mazumder
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
| | - Emma M Devenney
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
| | - Gabrielle L Adler
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Dominic B Rowe
- Macquarie University Centre for Motor Neuron Disease Research, Faculty of Medicine, Health and Human Sciences, Macquarie University, Sydney, NSW, Australia
| | - Jillian Kril
- Faculty of Medicine and Health, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
- Dementia Research Centre, Macquarie Medical School, Macquarie University, Sydney, NSW, Australia
| | - Glenda M Halliday
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
- Faculty of Medicine and Health, School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Matthew C Kiernan
- Brain and Mind Centre, University of Sydney, Sydney, NSW, Australia
- Institute of Clinical Neurosciences, Royal Prince Alfred Hospital, Sydney, NSW, Australia
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2
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Guida N, Sanguigno L, Mascolo L, Calabrese L, Serani A, Molinaro P, Lau CG, Annunziato L, Formisano L. The Transcriptional Complex Sp1/KMT2A by Up-Regulating Restrictive Element 1 Silencing Transcription Factor Accelerates Methylmercury-Induced Cell Death in Motor Neuron-Like NSC34 Cells Overexpressing SOD1-G93A. Front Neurosci 2021; 15:771580. [PMID: 34899171 PMCID: PMC8662822 DOI: 10.3389/fnins.2021.771580] [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: 09/06/2021] [Accepted: 11/08/2021] [Indexed: 11/13/2022] Open
Abstract
Methylmercury (MeHg) exposure has been related to amyotrophic lateral sclerosis (ALS) pathogenesis and molecular mechanisms of its neurotoxicity has been associated to an overexpression of the Restrictive Element 1 Silencing Transcription factor (REST). Herein, we evaluated the possibility that MeHg could accelerate neuronal death of the motor neuron-like NSC34 cells transiently overexpressing the human Cu2+/Zn2+superoxide dismutase 1 (SOD1) gene mutated at glycine 93 (SOD1-G93A). Indeed, SOD1-G93A cells exposed to 100 nM MeHg for 24 h showed a reduction in cell viability, as compared to cells transfected with empty vector or with unmutated SOD1 construct. Interestingly, cell survival reduction in SOD1-G93A cells was associated with an increase of REST mRNA and protein levels. Furthermore, MeHg increased the expression of the transcriptional factor Sp1 and promoted its binding to REST gene promoter sequence. Notably, Sp1 knockdown reverted MeHg-induced REST increase. Co-immunoprecipitation experiments demonstrated that Sp1 physically interacted with the epigenetic writer Lysine-Methyltransferase-2A (KMT2A). Moreover, knocking-down of KMT2A reduced MeHg-induced REST mRNA and protein increase in SOD1-G93A cells. Finally, we found that MeHg-induced REST up-regulation triggered necropoptotic cell death, monitored by RIPK1 increased protein expression. Interestingly, REST knockdown or treatment with the necroptosis inhibitor Necrostatin-1 (Nec) decelerated MeH-induced cell death in SOD1-G93A cells. Collectively, this study demonstrated that MeHg hastens necroptotic cell death in SOD1-G93A cells via Sp1/KMT2A complex, that by epigenetic mechanisms increases REST gene expression.
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Affiliation(s)
| | - Luca Sanguigno
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
| | - Luigi Mascolo
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
| | - Lucrezia Calabrese
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
| | - Angelo Serani
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
| | - Pasquale Molinaro
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
| | - C Geoffrey Lau
- Department of Neuroscience, City University of Hong Kong, Hong Kong, China
| | | | - Luigi Formisano
- Division of Pharmacology, Department of Neuroscience, Reproductive and Dentistry Sciences, School of Medicine, "Federico II" University of Naples, Naples, Italy
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3
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Shellikeri S, Keith J, Black SE, Zinman L, Yunusova Y. Neuropathology of Speech Network Distinguishes Bulbar From Nonbulbar Amyotrophic Lateral Sclerosis. J Neuropathol Exp Neurol 2020; 79:284-295. [PMID: 31951003 DOI: 10.1093/jnen/nlz130] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2019] [Accepted: 11/26/2019] [Indexed: 12/14/2022] Open
Abstract
Bulbar amyotrophic lateral sclerosis (ALS) is a debilitating neurodegenerative subtype affecting speech and swallowing motor functions as well as associated with the burden of cognitive deficits. The neuroanatomical underpinnings of bulbar ALS are not well understood. The aim of this study was to compare neuropathology of the speech network (SpN) between 3 cases of bulbar-onset ALS (bALS), 3 cases of spinal-onset ALS (sALS) with antemortem bulbar ALS (sALSwB) against 3 sALS without antemortem bulbar ALS (sALSnoB) and 3 controls. Regional distribution and severity of neuronal loss, TDP-43 (transactive response DNA-binding protein of 43 kDa), and tau proteinopathy were examined. All 3 bALS cases showed marked neuronal loss and severe proteinopathy across most SpN regions; sALSwB cases showed no neuronal loss but mild and variable TDP-43 pathology in focal regions; sALSnoB cases demonstrated an absence of pathology. Two bALS cases had coexisting tauopathy in SpN regions, which was not noted in any sALS cases. The findings suggested that bALS may have a distinct neuropathological signature characterized by marked neuronal loss and polypathology in the SpN. Milder TDP-43 pathology in the SpN for sALSwB cases suggested a link between severity of bulbar ALS and SpN damage. Findings support a clinicopathologic link between bulbar symptoms and pathology in the SpN.
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Affiliation(s)
- Sanjana Shellikeri
- Department of Speech-Language Pathology & Rehabilitation Sciences Institute, University of Toronto.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute
| | - Julia Keith
- Laboratory Medicine and Molecular Diagnostics, Anatomic Pathology, Sunnybrook Health Sciences Centre, and Laboratory Medicine and Pathobiology, Faculty of Medicine, University of Toronto
| | - Sandra E Black
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute.,Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre.,L.C. Campbell Cognitive Neurology Research Unit, Cognitive Neurology, Sunnybrook Research Institute, University of Toronto.,Rotman Research Institute, Baycrest
| | - Lorne Zinman
- Hurvitz Brain Sciences Program, Sunnybrook Research Institute.,Division of Neurology, Department of Medicine, Sunnybrook Health Sciences Centre.,L.C. Campbell Cognitive Neurology Research Unit, Cognitive Neurology, Sunnybrook Research Institute, University of Toronto
| | - Yana Yunusova
- Department of Speech-Language Pathology & Rehabilitation Sciences Institute, University of Toronto.,Hurvitz Brain Sciences Program, Sunnybrook Research Institute.,University Health Network - Toronto Rehabilitation Institute (YY), Toronto, Ontario, Canada
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Tan RH, Guennewig B, Dobson-Stone C, Kwok JB, Kril JJ, Kiernan MC, Hodges JR, Piguet O, Halliday GM. The underacknowledged PPA-ALS. Neurology 2019; 92:e1354-e1366. [DOI: 10.1212/wnl.0000000000007146] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 11/11/2018] [Indexed: 12/12/2022] Open
Abstract
ObjectiveTo assess the incidence, heritability, and neuropathology of primary progressive aphasia (PPA) with amyotrophic lateral sclerosis (ALS) in a large Australian cohort.MethodsA total of 130 patients with a primary nonfluent variant of PPA (nfvPPA) or semantic variant of PPA (svPPA) were assessed for concomitant ALS and a strong family history of neurodegenerative diseases (Goldman score ≤3). Neuropathologic examination was carried out in 28% (n = 36) of these PPA and PPA-ALS cases that had come to autopsy.ResultsALS was identified in 18% of patients with nfvPPA and 5% of patients with svPPA. PPA-ALS but not PPA was found to have a strong family history. At autopsy, frontotemporal lobar degeneration (FTLD)–TDP was identified in 100% of nfvPPA-ALS cases, 100% of svPPA-ALS cases, 24% of nfvPPA cases, and 78% of svPPA cases. Clinicopathologic assessments revealed a significant association between a strong family history and underlying FTLD-TDP pathology. Pathogenic mutations in known frontotemporal dementia (FTD)/ALS genes were identified in 100% of these familial PPA cases but only 50% of familial PPA-ALS cases, suggesting the involvement of novel genetic variants in this underacknowledged phenotype.ConclusionThe present study identified ALS in 12% of a large cohort of patients with nfvPPA and svPPA, which is comparable to the 10%–15% reported in FTD overall, indicating that a third of patients with FTD-ALS will have a predominant language profile. These findings highlight the importance of assessing for ALS in PPA, particularly since this is the only PPA phenotype in which a perfect clinicopathologic association has been reported in to date.
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Sun L, Zhang K, Zhai W, Li H, Shen H, Yu Z, Chen G. TAR DNA Binding Protein-43 Loss of Function Induced by Phosphorylation at S409/410 Blocks Autophagic Flux and Participates in Secondary Brain Injury After Intracerebral Hemorrhage. Front Cell Neurosci 2018; 12:79. [PMID: 29623031 PMCID: PMC5874314 DOI: 10.3389/fncel.2018.00079] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Accepted: 03/07/2018] [Indexed: 11/13/2022] Open
Abstract
This study aimed to determine the role of TAR DNA binding protein-43 (TDP-43) in intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI) and its underlying mechanisms. After ICH, expression of TDP-43 in the nucleus was significantly decreased, and its expression in the cytoplasm increased both in vivo and in vitro, which indicates that TDP-43 translocates from the nucleus to the cytoplasm during SBI after ICH. In addition, mutations at S409/410 of TDP-43 could inhibit its phosphorylation, attenuate nuclear loss, and abolish the increase in neuronal apoptosis in the subcortex. Inhibition of TDP-43 phosphorylation attenuated ICH-induced downregulation of mTOR activity and dynactin1 expression, which may relieve blocking of autophagosome-lysosome fusion and the increase of autophagosomal and lysosomal biogenesis induced by ICH. However, knockdown of TDP-43 could worsen ICH-induced SBI. Furthermore, TDP-43 could be dephosphorylated by calcineurin (CN), and CN activity was increased by OxyHb treatment. In conclusion, this study demonstrated that TDP-43 loss-of-function by phosphorylation at S409/410 may block autophagosome-lysosome fusion and induce elevation of LC3II and p62 levels by inhibiting the activity of mTOR and expression of dynactin1. This mechanism may play an important role in ICH-induced SBI, and TDP-43 may be a potential therapeutic target.
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Affiliation(s)
- Liang Sun
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, China.,Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Kai Zhang
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Weiwei Zhai
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Haiying Li
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Haitao Shen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Zhengquan Yu
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
| | - Gang Chen
- Department of Neurosurgery & Brain and Nerve Research Laboratory, The First Affiliated Hospital of Soochow University, Suzhou, China
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6
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Yang Y, Halliday GM, Hodges JR, Tan RH. von Economo Neuron Density and Thalamus Volumes in Behavioral Deficits in Frontotemporal Dementia Cases with and without a C9ORF72 Repeat Expansion. J Alzheimers Dis 2018; 58:701-709. [PMID: 28482638 DOI: 10.3233/jad-170002] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND The early and selective loss of von Economo neurons in the anterior cingulate cortex has been linked to behavioral deficits in frontotemporal dementia (FTD). Importantly, whether these neurons are also targeted in patients with the C9ORF72 repeat expansion has yet to be established. This is of particular interest given the recent evidence highlighting the thalamus rather than anterior cingulate cortex as a region of significant degeneration in patients with the C9ORF72 repeat expansion. OBJECTIVE To assess the von Economo neuron density and thalamus volumes in behavioral variant FTD (bvFTD) cases with the C9ORF72 repeat expansion, sporadic bvFTD, sporadic ALS, and controls. METHODS Volumetric and quantitative cell counting methods were employed to assess the von Economo neuron density and thalamus volumes in 37 pathologically-confirmed cases comprised of patients with bvFTD (n = 13) cases with the C9ORF72 repeat expansion (62% with psychosis), sporadic bvFTD (n = 8), sporadic amyotrophic lateral sclerosis (n = 7) and controls (n = 9). RESULTS von Economo neuron density was significantly reduced in sporadic bvFTD cases only. Thalamus degeneration was identified only in bvFTD cases with the C9ORF72 repeat expansion, and to a similar extent in cases with and without psychosis. No significant difference in von Economo neuron density or thalamus degeneration was seen between bvFTD cases with or without the C9ORF72 repeat expansion. CONCLUSION The present histological findings converge with neuroimaging results to corroborate the anterior cingulate cortex as a core region involved in sporadic bvFTD, and the thalamus as a major region targeted in patients with the C9ORF72 expansion.
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Affiliation(s)
- Yue Yang
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | - Glenda M Halliday
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia.,School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - John R Hodges
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia.,School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Rachel H Tan
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia.,School of Medical Sciences, University of New South Wales, Sydney, Australia
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7
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Tan RH, Yang Y, Halliday GM. Multiple neuronal pathologies are common in young patients with pathologically proven Frontotemporal lobar degeneration. Neuropathol Appl Neurobiol 2018; 44:522-532. [DOI: 10.1111/nan.12455] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2017] [Revised: 11/20/2017] [Accepted: 12/07/2017] [Indexed: 12/12/2022]
Affiliation(s)
- R H Tan
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,School of Medical Sciences, University of New South Wales, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
| | | | - G M Halliday
- Brain and Mind Centre, Sydney Medical School, The University of Sydney, Sydney, Australia.,School of Medical Sciences, University of New South Wales, Sydney, Australia.,Neuroscience Research Australia, Sydney, Australia
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Scott LL, Downing TG. A Single Neonatal Exposure to BMAA in a Rat Model Produces Neuropathology Consistent with Neurodegenerative Diseases. Toxins (Basel) 2017; 10:E22. [PMID: 29286334 PMCID: PMC5793109 DOI: 10.3390/toxins10010022] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Revised: 12/23/2017] [Accepted: 12/27/2017] [Indexed: 12/11/2022] Open
Abstract
Although cyanobacterial β-N-methylamino-l-alanine (BMAA) has been implicated in the development of Alzheimer's Disease (AD), Parkinson's Disease (PD) and Amyotrophic Lateral Sclerosis (ALS), no BMAA animal model has reproduced all the neuropathology typically associated with these neurodegenerative diseases. We present here a neonatal BMAA model that causes β-amyloid deposition, neurofibrillary tangles of hyper-phosphorylated tau, TDP-43 inclusions, Lewy bodies, microbleeds and microgliosis as well as severe neuronal loss in the hippocampus, striatum, substantia nigra pars compacta, and ventral horn of the spinal cord in rats following a single BMAA exposure. We also report here that BMAA exposure on particularly PND3, but also PND4 and 5, the critical period of neurogenesis in the rodent brain, is substantially more toxic than exposure to BMAA on G14, PND6, 7 and 10 which suggests that BMAA could potentially interfere with neonatal neurogenesis in rats. The observed selective toxicity of BMAA during neurogenesis and, in particular, the observed pattern of neuronal loss observed in BMAA-exposed rats suggest that BMAA elicits its effect by altering dopamine and/or serotonin signaling in rats.
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Affiliation(s)
- Laura Louise Scott
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
| | - Timothy Grant Downing
- Department of Biochemistry and Microbiology, Nelson Mandela University, P.O. Box 77 000, Port Elizabeth 6031, South Africa.
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Tan RH, Yang Y, Kim WS, Dobson-Stone C, Kwok JB, Kiernan MC, Halliday GM. Distinct TDP-43 inclusion morphologies in frontotemporal lobar degeneration with and without amyotrophic lateral sclerosis. Acta Neuropathol Commun 2017; 5:76. [PMID: 29078806 PMCID: PMC5658959 DOI: 10.1186/s40478-017-0480-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2017] [Accepted: 10/09/2017] [Indexed: 01/08/2023] Open
Abstract
The identification of the TAR DNA-binding protein 43 (TDP-43) as the ubiquitinated cytoplasmic inclusions in frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS) confirmed that these two diseases share similar mechanisms, likely to be linked to the abnormal hyperphosphorylation, ubiquitination and cleavage of pathological TDP-43. Importantly however, a quantitative analysis of TDP-43 inclusions in predilection cortical regions of FTLD, FTLD-ALS and ALS cases has not been undertaken. The present study set out to assess this and demonstrates that distinct TDP-43 inclusion morphologies exist in the anterior cingulate cortex, but not the motor cortex of FTLD and FTLD-ALS. Specifically, in the anterior cingulate cortex of FTLD cases, significant rounded TDP-43 inclusions and rare circumferential TDP-43 inclusions were identified. In contrast, FTLD-ALS cases revealed significant circumferential TDP-43 inclusions and rare rounded TDP-43 inclusions in the anterior cingulate cortex. Distinct TDP-43 inclusion morphologies in the anterior cingulate cortex of FTLD and FTLD-ALS may be linked to heterogeneity in the ubiquitination of pathological TDP-43 inclusions, with the present study providing evidence to suggest the involvement of distinct pathomechanisms in these two overlapping clinical syndromes.
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