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Majumder M, Dutta D. Oligodendrocyte Dysfunction in Tauopathy: A Less Explored Area in Tau-Mediated Neurodegeneration. Cells 2024; 13:1112. [PMID: 38994964 PMCID: PMC11240328 DOI: 10.3390/cells13131112] [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: 06/05/2024] [Revised: 06/25/2024] [Accepted: 06/25/2024] [Indexed: 07/13/2024] Open
Abstract
Aggregation of the microtubule-associated protein tau (MAPT) is the hallmark pathology in a spectrum of neurodegenerative disorders collectively called tauopathies. Physiologically, tau is an inherent neuronal protein that plays an important role in the assembly of microtubules and axonal transport. However, disease-associated mutations of this protein reduce its binding to the microtubule components and promote self-aggregation, leading to formation of tangles in neurons. Tau is also expressed in oligodendrocytes, where it has significant developmental roles in oligodendrocyte maturation and myelin synthesis. Oligodendrocyte-specific tau pathology, in the form of fibrils and coiled coils, is evident in major tauopathies including progressive supranuclear palsy (PSP), corticobasal degeneration (CBD), and Pick's disease (PiD). Multiple animal models of tauopathy expressing mutant forms of MAPT recapitulate oligodendroglial tau inclusions with potential to cause degeneration/malfunction of oligodendrocytes and affecting the neuronal myelin sheath. Till now, mechanistic studies heavily concentrated on elucidating neuronal tau pathology. Therefore, more investigations are warranted to comprehensively address tau-induced pathologies in oligodendrocytes. The present review provides the current knowledge available in the literature about the intricate relations between tau and oligodendrocytes in health and diseases.
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Affiliation(s)
- Moumita Majumder
- Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, SC 29425, USA;
| | - Debashis Dutta
- Department of Pediatrics, Darby’s Children Research Institute, Medical University of South Carolina, Charleston, SC 29425, USA
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Chu D, Yang X, Wang J, Zhou Y, Gu JH, Miao J, Wu F, Liu F. Tau truncation in the pathogenesis of Alzheimer's disease: a narrative review. Neural Regen Res 2024; 19:1221-1232. [PMID: 37905868 DOI: 10.4103/1673-5374.385853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Accepted: 07/25/2023] [Indexed: 11/02/2023] Open
Abstract
ABSTRACT Alzheimer's disease is characterized by two major neuropathological hallmarks-the extracellular β-amyloid plaques and intracellular neurofibrillary tangles consisting of aggregated and hyperphosphorylated Tau protein. Recent studies suggest that dysregulation of the microtubule-associated protein Tau, especially specific proteolysis, could be a driving force for Alzheimer's disease neurodegeneration. Tau physiologically promotes the assembly and stabilization of microtubules, whereas specific truncated fragments are sufficient to induce abnormal hyperphosphorylation and aggregate into toxic oligomers, resulting in them gaining prion-like characteristics. In addition, Tau truncations cause extensive impairments to neural and glial cell functions and animal cognition and behavior in a fragment-dependent manner. This review summarizes over 60 proteolytic cleavage sites and their corresponding truncated fragments, investigates the role of specific truncations in physiological and pathological states of Alzheimer's disease, and summarizes the latest applications of strategies targeting Tau fragments in the diagnosis and treatment of Alzheimer's disease.
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Affiliation(s)
- Dandan Chu
- Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, NMPA Key Laboratory for Research and Evaluation of Tissue Engineering Technology Products, Co-innovation Center of Neuroregeneration, Nantong University, Nantong, Jiangsu Province, China
| | - Xingyue Yang
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
| | - Jing Wang
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
| | - Yan Zhou
- Department of Biochemistry and Molecular Biology, School of Medicine, Nantong University, Nantong, Jiangsu Province, China
| | - Jin-Hua Gu
- Department of Clinical Pharmacy, Affiliated Maternity and Child Health Care Hospital of Nantong University, Nantong University, Nantong, Jiangsu Province, China
| | - Jin Miao
- Laboratory of Animal Center, Nantong University, Nantong, Jiangsu Province, China
| | - Feng Wu
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, Jiangsu Province, China
| | - Fei Liu
- Department of Neurochemistry, Inge Grundke-Iqbal Research Floor, New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY, USA
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Zheng H, Sun H, Cai Q, Tai HC. The Enigma of Tau Protein Aggregation: Mechanistic Insights and Future Challenges. Int J Mol Sci 2024; 25:4969. [PMID: 38732197 PMCID: PMC11084794 DOI: 10.3390/ijms25094969] [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: 03/30/2024] [Revised: 04/20/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Tau protein misfolding and aggregation are pathological hallmarks of Alzheimer's disease and over twenty neurodegenerative disorders. However, the molecular mechanisms of tau aggregation in vivo remain incompletely understood. There are two types of tau aggregates in the brain: soluble aggregates (oligomers and protofibrils) and insoluble filaments (fibrils). Compared to filamentous aggregates, soluble aggregates are more toxic and exhibit prion-like transmission, providing seeds for templated misfolding. Curiously, in its native state, tau is a highly soluble, heat-stable protein that does not form fibrils by itself, not even when hyperphosphorylated. In vitro studies have found that negatively charged molecules such as heparin, RNA, or arachidonic acid are generally required to induce tau aggregation. Two recent breakthroughs have provided new insights into tau aggregation mechanisms. First, as an intrinsically disordered protein, tau is found to undergo liquid-liquid phase separation (LLPS) both in vitro and inside cells. Second, cryo-electron microscopy has revealed diverse fibrillar tau conformations associated with different neurodegenerative disorders. Nonetheless, only the fibrillar core is structurally resolved, and the remainder of the protein appears as a "fuzzy coat". From this review, it appears that further studies are required (1) to clarify the role of LLPS in tau aggregation; (2) to unveil the structural features of soluble tau aggregates; (3) to understand the involvement of fuzzy coat regions in oligomer and fibril formation.
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Affiliation(s)
| | | | | | - Hwan-Ching Tai
- State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, State Key Laboratory of Molecular Vaccinology and Molecular Diagnostics, National Innovation Platform for Industry-Education Integration in Vaccine Research, School of Public Health, Xiamen University, Xiamen 361102, China
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Nguyen HD, Kim YE, Nhat Nguyen LT, Kwak IH, Lee YK, Kim YJ, Hai Nguyen TT, Pham HN, Ma HI. Upregulation of immunoproteasome PSMB8 is associated with Parkinson's disease. Parkinsonism Relat Disord 2023; 114:105797. [PMID: 37562243 DOI: 10.1016/j.parkreldis.2023.105797] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 08/03/2023] [Accepted: 08/03/2023] [Indexed: 08/12/2023]
Abstract
BACKGROUND Immunoproteasome, a part of ubiquitin-proteasome system, is involved in immune response as well as protein degradation. However, the relationship between immunoproteasome and Parkinson's disease (PD) was not evaluated clearly. We hypothesized that the shift of immunoproteasome attributes to PD pathogenesis due to its role in inflammation and protein homeostasis. OBJECTIVE To determine whether immunoproteasome in peripheral blood mononuclear cells (PBMC) and brain is expressed differently between patients with PD and healthy controls (HC). METHODS Blood samples were collected from 19 HC to 40 patients with PD of comparable ages. Peripheral blood mononuclear cells were isolated and followed by RT-qPCR to measure the mRNA levels of three catalytic subunits of immunoproteasome, namely, PSMB8, PSMB9, and PSMB10. Then, the protein levels of each subunit were measured by western blot. Finally, we confirmed the altered immunoproteasome subunit in the post-mortem human brain of PD. RESULTS In PBMCs, PSMB8 mRNA expression of PD group significantly increased compared to HC (p = 0.004), whereas PSMB9 and PSMB10 mRNA were not different between the PD and HC. The ratio of PSMB10 and PSMB8 mRNA (PSMB10/8 ratio) also reflected the significant difference between the PD and HC (p = 0.002). The PSMB10/8 ratio was well correlated with the UPDRS total and Part III score in the early stage of PD (Hoehn and Yahr ≤2.5) or drug-naïve PD subgroups. In terms of the protein level of immunoproteasome subunits in PBMCs, the increase of PSMB8 protein was observed in PD compared to HC (p = 0.0009), while PSMB9 and PSMB10 were not different between groups. Finally, we confirmed that immunoproteasome PSMB8 was expressed abundantly in the postmortem PD brain compared with normal control. CONCLUSION Our novel findings implicate that immunoproteasome PSMB8 is engaged in PD pathomechanism.
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Affiliation(s)
- Huu Dat Nguyen
- Department of Medical Sciences, Graduate School of Hallym University, Chuncheon, Gangwon, 24252, South Korea; Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - Young Eun Kim
- Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea; Hallym Neurological Institute, Hallym University, Anyang, Gyeonggi, 14068, South Korea.
| | - Linh Thi Nhat Nguyen
- Department of Medical Sciences, Graduate School of Hallym University, Chuncheon, Gangwon, 24252, South Korea; Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - In Hee Kwak
- Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea; Hallym Neurological Institute, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - Yoon Kyoung Lee
- Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - Yun Joong Kim
- Department of Neurology, Yongin Severance Hospital, Yonsei University College of Medicine, Yongin, Gyeonggi, South Korea
| | - Thanh Thi Hai Nguyen
- Department of Medical Sciences, Graduate School of Hallym University, Chuncheon, Gangwon, 24252, South Korea; Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - Hong Ngoc Pham
- Department of Medical Sciences, Graduate School of Hallym University, Chuncheon, Gangwon, 24252, South Korea; Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea
| | - Hyeo-Il Ma
- Department of Neurology, Hallym University Sacred Heart Hospital, Hallym University, Anyang, Gyeonggi, 14068, South Korea; Hallym Neurological Institute, Hallym University, Anyang, Gyeonggi, 14068, South Korea
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Padmanabhan S, Manjithaya R. Leaderless secretory proteins of the neurodegenerative diseases via TNTs: a structure-function perspective. Front Mol Neurosci 2023; 16:983108. [PMID: 37396786 PMCID: PMC10308029 DOI: 10.3389/fnmol.2023.983108] [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: 06/30/2022] [Accepted: 05/26/2023] [Indexed: 07/04/2023] Open
Abstract
Neurodegenerative disease-causing proteins such as alpha-synuclein, tau, and huntingtin are known to traverse across cells via exosomes, extracellular vesicles and tunneling nanotubes (TNTs). There seems to be good synergy between exosomes and TNTs in intercellular communication. Interestingly, many of the known major neurodegenerative proteins/proteolytic products are leaderless and are also reported to be secreted out of the cell via unconventional protein secretion. Such classes contain intrinsically disordered proteins and regions (IDRs) within them. The dynamic behavior of these proteins is due to their heterogenic conformations that is exhibited owing to various factors that occur inside the cells. The amino acid sequence along with the chemical modifications has implications on the functional roles of IDRs inside the cells. Proteins that form aggregates resulting in neurodegeneration become resistant to degradation by the processes of autophagy and proteasome system thus leading to Tunneling nanotubes, TNT formation. The proteins that traverse across TNTs may or may not be dependent on the autophagy machinery. It is not yet clear whether the conformation of the protein plays a crucial role in its transport from one cell to another without getting degraded. Although there is some experimental data, there are many grey areas which need to be revisited. This review provides a different perspective on the structural and functional aspects of these leaderless proteins that get secreted outside the cell. In this review, attention has been focused on the characteristic features that lead to aggregation of leaderless secretory proteins (from structural-functional aspect) with special emphasis on TNTs.
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Pockes S, Walters MA, Ashe KH. Targeting caspase-2 interactions with tau in Alzheimer's disease and related dementias. Transl Res 2023; 254:34-40. [PMID: 36343883 PMCID: PMC9991976 DOI: 10.1016/j.trsl.2022.10.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 10/26/2022] [Accepted: 10/30/2022] [Indexed: 11/06/2022]
Abstract
Targeting amyloid-β plaques and tau tangles has failed to provide effective treatments for Alzheimer's disease and related dementias (ADRD). A more fruitful pathway to ADRD therapeutics may be the development of therapies that target common signaling pathways that disrupt synaptic connections and impede communication between neurons. In this review, we present our characterization of a signaling pathway common to several neurological diseases featuring dementia including Alzheimer's disease, frontotemporal dementia, Lewy body dementia, and Huntington's disease. This signaling pathway features the cleavage of tau by caspase-2 (Casp2) yielding Δtau314 (Casp2/tau/Δtau314). Through a not yet fully delineated mechanism, Δtau314 catalyzes the mislocalization and accumulation of tau to dendritic spines leading to the internalization of AMPA receptors and the concomitant weakening of synaptic transmission. Here, we review the accumulated evidence supporting Casp2 as a druggable target and its importance in ADRD. Additionally, we provide a brief overview of our initial medicinal chemistry explorations aimed at the preparation of novel, brain penetrant Casp2 inhibitors. We anticipate that this review will spark broader interest in Casp2 as a target for restoring synaptic dysfunction in ADRD.
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Affiliation(s)
- Steffen Pockes
- Institute of Pharmacy, University of Regensburg, Regensburg, Germany; Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota; Department of Neurology, University of Minnesota, Minneapolis, Minnesota.
| | - Michael A Walters
- Department of Medicinal Chemistry, Institute for Therapeutics Discovery and Development, University of Minnesota, Minneapolis, Minnesota.
| | - Karen H Ashe
- Department of Neurology, University of Minnesota, Minneapolis, Minnesota.
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Reassessment of Neuronal Tau Distribution in Adult Human Brain and Implications for Tau Pathobiology. Acta Neuropathol Commun 2022; 10:94. [PMID: 35765058 PMCID: PMC9237980 DOI: 10.1186/s40478-022-01394-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 06/10/2022] [Indexed: 11/30/2022] Open
Abstract
Tau is a predominantly neuronal, soluble and natively unfolded protein that can bind and stabilize microtubules in the central nervous system. Tau has been extensively studied over several decades, especially in the context of neurodegenerative diseases where it can aberrantly aggregate to form a spectrum of pathological inclusions. The presence of tau inclusions in the form of neurofibrillary tangles, neuropil threads and dystrophic neurites within senile plaques are essential and defining features of Alzheimer’s disease. The current dogma favors the notion that tau is predominantly an axonal protein, and that in Alzheimer’s disease there is a redistribution of tau towards the neuronal soma that is associated with the formation of pathological inclusions such as neurofibrillary tangles and neuropil threads. Using novel as well as previously established highly specific tau antibodies, we demonstrate that contrary to this overwhelmingly accepted fact, as asserted in numerous articles and reviews, in adult human brain, tau is more abundant in cortical gray matter that is enriched in neuronal soma and dendrites compared to white matter that is predominantly rich in neuronal axons. Additionally, in Alzheimer’s disease tau pathology is significantly more abundant in the brain cortical gray matter of affected brain regions compared to the adjacent white matter regions. These findings have important implications for the biological function of tau as well as the mechanisms involved in the progressive spread of tau associated with the insidious nature of Alzheimer’s disease.
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