1
|
Chakrabarty A, Newey SE, Promi MM, Agbetiameh BK, Munro D, Brodersen PJN, Gothard G, Mahfooz K, Mengual JP, Vyazovskiy VV, Akerman CJ. sUPRa is a dual-color reporter for unbiased quantification of the unfolded protein response with cellular resolution. Sci Rep 2024; 14:14990. [PMID: 38951511 PMCID: PMC11217371 DOI: 10.1038/s41598-024-65611-2] [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: 06/12/2024] [Accepted: 06/21/2024] [Indexed: 07/03/2024] Open
Abstract
The unfolded protein response (UPR) maintains proteostasis upon endoplasmic reticulum (ER) stress, and is initiated by a range of physiological and pathological processes. While there have been advances in developing fluorescent reporters for monitoring individual signaling pathways of the UPR, this approach may not capture a cell's overall UPR activity. Here we describe a novel sensor of UPR activity, sUPRa, which is designed to report the global UPR. sUPRa displays excellent response characteristics, outperforms reporters of individual UPR pathways in terms of sensitivity and kinetics, and responds to a range of different ER stress stimuli. Furthermore, sUPRa's dual promoter and fluorescent protein design ensures that both UPR-active and inactive cells are detected, and controls for reporter copy number. Using sUPRa, we reveal UPR activation in layer 2/3 pyramidal neurons of mouse cerebral cortex following a period of sleep deprivation. sUPRa affords new opportunities for quantifying physiological UPR activity with cellular resolution.
Collapse
Affiliation(s)
- Atreyi Chakrabarty
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Sarah E Newey
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Maisha M Promi
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Belinda K Agbetiameh
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Daniella Munro
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Paul J N Brodersen
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Gemma Gothard
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Kashif Mahfooz
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Jose P Mengual
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Sherrington Road, Oxford, OX1 3PT, UK
| | - Vladyslav V Vyazovskiy
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Sherrington Road, Oxford, OX1 3PT, UK
| | - Colin J Akerman
- Department of Pharmacology, University of Oxford, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
| |
Collapse
|
2
|
POSCAbilities: The Application of the Prion Organotypic Slice Culture Assay to Neurodegenerative Disease Research. Biomolecules 2020; 10:biom10071079. [PMID: 32698402 PMCID: PMC7407827 DOI: 10.3390/biom10071079] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/06/2020] [Accepted: 07/16/2020] [Indexed: 12/14/2022] Open
Abstract
Prion diseases are fatal, transmissible neurodegenerative disorders whose pathogenesis is driven by the misfolding, self-templating and cell-to-cell spread of the prion protein. Other neurodegenerative diseases such as Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis and Huntington’s disease, share some of these prion-like features, with different aggregation-prone proteins. Consequently, researchers have begun to apply prion-specific techniques, like the prion organotypic slice culture assay (POSCA), to these disorders. In this review we explore the ways in which the prion phenomenon has been used in organotypic cultures to study neurodegenerative diseases from the perspective of protein aggregation and spreading, strain propagation, the role of glia in pathogenesis, and efficacy of drug treatments. We also present an overview of the advantages and disadvantages of this culture system compared to in vivo and in vitro models and provide suggestions for new directions.
Collapse
|
3
|
Buratti E. Targeting TDP-43 proteinopathy with drugs and drug-like small molecules. Br J Pharmacol 2020; 178:1298-1315. [PMID: 32469420 DOI: 10.1111/bph.15148] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 02/06/2023] Open
Abstract
Following the discovery of the involvement of the ribonucleoprotein TDP-43 in amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), a major research focus has been to develop treatments that can prevent or alleviate these disease conditions. One pharmacological approach has been to use TDP-43-based disease models to test small molecules and drugs already known to have some therapeutic effect in a variety of neurodegenerative conditions. In parallel, various disease models have been used to perform high-throughput screens of drugs and small compound libraries. The aim of this review will be to provide a general overview of the compounds that have been described to alter pathological characteristics of TDP-43. These include expression levels, cytoplasmic mis-localization, post-translational modifications, cleavage, stress granule recruitment and aggregation. In parallel, this review will also address the use of compounds that modify the autophagic/proteasome systems that are known to target TDP-43 misfolding and aggregation. LINKED ARTICLES: This article is part of a themed issue on Neurochemistry in Japan. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v178.6/issuetoc.
Collapse
Affiliation(s)
- Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Trieste, Italy
| |
Collapse
|
4
|
Endoplasmic Reticulum Stress Signalling Induces Casein Kinase 1-Dependent Formation of Cytosolic TDP-43 Inclusions in Motor Neuron-Like Cells. Neurochem Res 2020; 45:1354-1364. [PMID: 31280399 PMCID: PMC7260270 DOI: 10.1007/s11064-019-02832-2] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 06/17/2019] [Accepted: 06/19/2019] [Indexed: 12/30/2022]
Abstract
Motor neuron disease (MND) is a progressive neurodegenerative disease with no effective treatment. One of the principal pathological hallmarks is the deposition of TAR DNA binding protein 43 (TDP-43) in cytoplasmic inclusions. TDP-43 aggregation occurs in both familial and sporadic MND; however, the mechanism of endogenous TDP-43 aggregation in disease is incompletely understood. This study focused on the induction of cytoplasmic accumulation of endogenous TDP-43 in the motor neuronal cell line NSC-34. The endoplasmic reticulum (ER) stressor tunicamycin induced casein kinase 1 (CK1)-dependent cytoplasmic accumulation of endogenous TDP-43 in differentiated NSC-34 cells, as seen by immunocytochemistry. Immunoblotting showed that induction of ER stress had no effect on abundance of TDP-43 or phosphorylated TDP-43 in the NP-40/RIPA soluble fraction. However, there were significant increases in abundance of TDP-43 and phosphorylated TDP-43 in the NP-40/RIPA-insoluble, urea-soluble fraction, including high molecular weight species. In all cases, these increases were lowered by CK1 inhibition. Thus ER stress signalling, as induced by tunicamycin, causes CK1-dependent phosphorylation of TDP-43 and its consequent cytosolic accumulation.
Collapse
|
5
|
Croft CL, Futch HS, Moore BD, Golde TE. Organotypic brain slice cultures to model neurodegenerative proteinopathies. Mol Neurodegener 2019; 14:45. [PMID: 31791377 PMCID: PMC6889333 DOI: 10.1186/s13024-019-0346-0] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/13/2019] [Indexed: 01/30/2023] Open
Abstract
Organotypic slice cultures of brain or spinal cord have been a longstanding tool in neuroscience research but their utility for understanding Alzheimer's disease (AD) and other neurodegenerative proteinopathies has only recently begun to be evaluated. Organotypic brain slice cultures (BSCs) represent a physiologically relevant three-dimensional model of the brain. BSCs support all the central nervous system (CNS) cell types and can be produced from brain areas involved in neurodegenerative disease. BSCs can be used to better understand the induction and significance of proteinopathies underlying the development and progression of AD and other neurodegenerative disorders, and in the future may serve as bridging technologies between cell culture and in vivo experiments for the development and evaluation of novel therapeutic targets and strategies. We review the initial development and general use of BSCs in neuroscience research and highlight the advantages of these cultures as an ex vivo model. Subsequently we focus on i) BSC-based modeling of AD and other neurodegenerative proteinopathies ii) use of BSCs to understand mechanisms underlying these diseases and iii) how BSCs can serve as tools to screen for suitable therapeutics prior to in vivo investigations. Finally, we will examine i) open questions regarding the use of such cultures and ii) how emerging technologies such as recombinant adeno-associated viruses (rAAV) may be combined with these models to advance translational research relevant to neurodegenerative disorders.
Collapse
Affiliation(s)
- C L Croft
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - H S Futch
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - B D Moore
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, FL, 32610, USA
| | - T E Golde
- Department of Neuroscience, College of Medicine, University of Florida, Gainesville, FL, 32610, USA. .,Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida, Gainesville, FL, 32610, USA. .,McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL, 32610, USA.
| |
Collapse
|
6
|
Jawaid A, Khan R, Polymenidou M, Schulz PE. Disease-modifying effects of metabolic perturbations in ALS/FTLD. Mol Neurodegener 2018; 13:63. [PMID: 30509290 PMCID: PMC6278047 DOI: 10.1186/s13024-018-0294-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Accepted: 11/13/2018] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD) are two fatal neurodegenerative disorders with considerable clinical, pathological and genetic overlap. Both disorders are characterized by the accumulation of pathological protein aggregates that contain a number of proteins, most notably TAR DNA binding protein 43 kDa (TDP-43). Surprisingly, recent clinical studies suggest that dyslipidemia, high body mass index, and type 2 diabetes mellitus are associated with better clinical outcomes in ALS. Moreover, ALS and FTLD patients have a significantly lower incidence of cardiovascular disease, supporting the idea that an unfavorable metabolic profile may be beneficial in ALS and FTLD. The two most widely studied ALS/FTLD models, super-oxide dismutase 1 (SOD1) and TAR DNA binding protein of 43 kDA (TDP-43), reveal metabolic dysfunction and a positive effect of metabolic strategies on disease onset and/or progression. In addition, molecular studies reveal a role for ALS/FTLD-associated proteins in the regulation of cellular and whole-body metabolism. Here, we systematically evaluate these observations and discuss how changes in cellular glucose/lipid metabolism may result in abnormal protein aggregations in ALS and FTLD, which may have important implications for new treatment strategies for ALS/FTLD and possibly other neurodegenerative conditions.
Collapse
Affiliation(s)
- Ali Jawaid
- Laboratory of Neuroepigenetics, Brain Research Institute, University of Zurich (UZH)/ Swiss Federal Institute of Technology (ETH), Winterthurerstr. 190, 8057, Zurich, Switzerland. .,Syed Babar Ali School of Science and Engineering (SBASSE), Lahore University of Management Sciences (LUMS), Lahore, Pakistan.
| | - Romesa Khan
- Syed Babar Ali School of Science and Engineering (SBASSE), Lahore University of Management Sciences (LUMS), Lahore, Pakistan
| | | | - Paul E Schulz
- Department of Neurology, The McGovern Medical School of UT Health, Houston, TX, USA
| |
Collapse
|
7
|
Hock EM, Polymenidou M. Prion-like propagation as a pathogenic principle in frontotemporal dementia. J Neurochem 2017; 138 Suppl 1:163-83. [PMID: 27502124 PMCID: PMC6680357 DOI: 10.1111/jnc.13668] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 04/22/2016] [Accepted: 05/11/2016] [Indexed: 12/12/2022]
Abstract
Frontotemporal dementia is a devastating neurodegenerative disease causing stark alterations in personality and language. Characterized by severe atrophy of the frontal and temporal brain lobes, frontotemporal dementia (FTD) shows extreme heterogeneity in clinical presentation, genetic causes, and pathological findings. Like most neurodegenerative diseases, the initial symptoms of FTD are subtle, but increase in severity over time, as the disease progresses. Clinical progression is paralleled by exacerbation of pathological findings and the involvement of broader brain regions, which currently lack mechanistic explanation. Yet, a flurry of studies indicate that protein aggregates accumulating in neurodegenerative diseases can act as propagating entities, amplifying their pathogenic conformation, in a way similar to infectious prions. In this prion‐centric view, FTD can be divided into three subtypes, TDP‐43 or FUS proteinopathy and tauopathy. Here, we review the current evidence that FTD‐linked pathology propagates in a prion‐like manner and discuss the implications of these findings for disease progression and heterogeneity.
Frontotemporal dementia (FTD) is a progressive neurodegenerative disease causing severe personality dysfunctions, characterized by profound heterogeneity. Accumulation of tau, TDP‐43 or FUS cytoplasmic aggregates characterize molecularly distinct and non‐overlapping FTD subtypes. Here, we discuss the current evidence suggesting that prion‐like propagation and cell‐to‐cell spread of each of these cytoplasmic aggregates may underlie disease progression and heterogeneity.
This article is part of the Frontotemporal Dementia special issue.
Collapse
Affiliation(s)
- Eva-Maria Hock
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
| | | |
Collapse
|
8
|
Humpel C. Organotypic brain slice cultures: A review. Neuroscience 2015; 305:86-98. [PMID: 26254240 PMCID: PMC4699268 DOI: 10.1016/j.neuroscience.2015.07.086] [Citation(s) in RCA: 278] [Impact Index Per Article: 30.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 07/24/2015] [Accepted: 07/31/2015] [Indexed: 12/27/2022]
Abstract
In vitro cell cultures are an important tool for obtaining insights into cellular processes in an isolated system and a supplement to in vivo animal experiments. While primary dissociated cultures permit a single homogeneous cell population to be studied, there is a clear need to explore the function of brain cells in a three-dimensional system where the main architecture of the cells is preserved. Thus, organotypic brain slice cultures have proven to be very useful in investigating cellular and molecular processes of the brain in vitro. This review summarizes (1) the historical development of organotypic brain slices focusing on the membrane technology, (2) methodological aspects regarding culturing procedures, age of donors or media, (3) whether the cholinergic neurons serve as a model of neurodegeneration in Alzheimer’s disease, (4) or the nigrostriatal dopaminergic neurons as a model of Parkinson’s disease and (5) how the vascular network can be studied, especially with regard to a synthetic blood–brain barrier. This review will also highlight some limits of the model and give an outlook on future applications.
Collapse
Affiliation(s)
- C Humpel
- Laboratory of Psychiatry and Experimental Alzheimer's Research, Department of Psychiatry and Psychotherapy, Medical University of Innsbruck, Anichstrasse 35, A-6020 Innsbruck, Austria.
| |
Collapse
|
9
|
Maniecka Z, Polymenidou M. From nucleation to widespread propagation: A prion-like concept for ALS. Virus Res 2015; 207:94-105. [PMID: 25656065 DOI: 10.1016/j.virusres.2014.12.032] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Revised: 12/12/2014] [Accepted: 12/29/2014] [Indexed: 12/12/2022]
Abstract
Propagation of pathological protein assemblies via a prion-like mechanism has been suggested to drive neurodegenerative diseases, such as Parkinson's and Alzheimer's. Recently, amyotrophic lateral sclerosis (ALS)-linked proteins, such as SOD1, TDP-43 and FUS were shown to follow self-perpetuating seeded aggregation, thereby adding ALS to the group of prion-like disorders. The cell-to-cell spread of these pathological protein assemblies and their pathogenic mechanism is poorly understood. However, as ALS is a non-cell autonomous disease and pathology in glial cells was shown to contribute to motor neuron damage, spreading mechanisms are likely to underlie disease progression via the interplay between affected neurons and their neighboring glial cells.
Collapse
Affiliation(s)
- Zuzanna Maniecka
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
| | - Magdalini Polymenidou
- Institute of Molecular Life Sciences, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
| |
Collapse
|
10
|
D'Alton S, Lewis J. Therapeutic and diagnostic challenges for frontotemporal dementia. Front Aging Neurosci 2014; 6:204. [PMID: 25191265 PMCID: PMC4137452 DOI: 10.3389/fnagi.2014.00204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 07/25/2014] [Indexed: 12/12/2022] Open
Abstract
In the search for therapeutic modifiers, frontotemporal dementia (FTD) has traditionally been overshadowed by other conditions such as Alzheimer's disease (AD). A clinically and pathologically diverse condition, FTD has been galvanized by a number of recent discoveries such as novel genetic variants in familial and sporadic forms of disease and the identification of TAR DNA binding protein of 43 kDa (TDP-43) as the defining constituent of inclusions in more than half of cases. In combination with an ever-expanding knowledge of the function and dysfunction of tau-a protein which is pathologically aggregated in the majority of the remaining cases-there exists a greater understanding of FTD than ever before. These advances may indicate potential approaches for the development of hypothetical therapeutics, but FTD remains highly complex and the roles of tau and TDP-43 in neurodegeneration are still wholly unclear. Here the challenges facing potential therapeutic strategies are discussed, which include sufficiently accurate disease diagnosis and sophisticated technology to deliver effective therapies.
Collapse
Affiliation(s)
- Simon D'Alton
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida Gainesville, FL, USA
| | - Jada Lewis
- Department of Neuroscience, Center for Translational Research in Neurodegenerative Disease, College of Medicine, University of Florida Gainesville, FL, USA
| |
Collapse
|
11
|
Budini M, Baralle FE, Buratti E. Targeting TDP-43 in neurodegenerative diseases. Expert Opin Ther Targets 2014; 18:617-32. [DOI: 10.1517/14728222.2014.896905] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
|
12
|
Hebron M, Chen W, Miessau MJ, Lonskaya I, Moussa CEH. Parkin reverses TDP-43-induced cell death and failure of amino acid homeostasis. J Neurochem 2013; 129:350-61. [PMID: 24298989 DOI: 10.1111/jnc.12630] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 11/27/2013] [Accepted: 11/27/2013] [Indexed: 12/13/2022]
Abstract
The E3 ubiquitin ligase Parkin plays a central role in the pathogenesis of many neurodegenerative diseases. Parkin promotes specific ubiquitination and affects the localization of transactivation response DNA-binding protein 43 (TDP-43), which controls the translation of thousands of mRNAs. Here we tested the effects of lentiviral Parkin and TDP-43 expression on amino acid metabolism in the rat motor cortex using high frequency ¹³C NMR spectroscopy. TDP-43 expression increased glutamate levels, decreased the levels of other amino acids, including glutamine, aspartate, leucine and isoleucine, and impaired mitochondrial tricarboxylic acid cycle. TDP-43 induced lactate accumulation and altered the balance between excitatory (glutamate) and inhibitory (GABA) neurotransmitters. Parkin restored amino acid levels, neurotransmitter balance and tricarboxylic acid cycle metabolism, rescuing neurons from TDP-43-induced apoptotic death. Furthermore, TDP-43 expression led to an increase in 4E-BP levels, perhaps altering translational control and deregulating amino acid synthesis; while Parkin reversed the effects of TDP-43 on the 4E-BP signaling pathway. Taken together, these data suggest that Parkin may affect TDP-43 localization and mitigate its effects on 4E-BP signaling and loss of amino acid homeostasis.
Collapse
Affiliation(s)
- Michaeline Hebron
- Department of Neuroscience, Georgetown University Medical Center, Washington, District of Columbia, USA
| | | | | | | | | |
Collapse
|
13
|
Udan-Johns M, Bengoechea R, Bell S, Shao J, Diamond MI, True HL, Weihl CC, Baloh RH. Prion-like nuclear aggregation of TDP-43 during heat shock is regulated by HSP40/70 chaperones. Hum Mol Genet 2013; 23:157-70. [PMID: 23962724 DOI: 10.1093/hmg/ddt408] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
TDP-43 aggregation in the cytoplasm or nucleus is a key feature of the pathology of amyotrophic lateral sclerosis and frontotemporal dementia and is observed in numerous other neurodegenerative diseases, including Alzheimer's disease. Despite this fact, the inciting events leading to TDP-43 aggregation remain unclear. We observed that endogenous TDP-43 undergoes reversible aggregation in the nucleus after the heat shock and that this behavior is mediated by the C-terminal prion domain. Substitution of the prion domain from TIA-1 or an authentic yeast prion domain from RNQ1 into TDP-43 can completely recapitulate heat shock-induced aggregation. TDP-43 is constitutively bound to members of the Hsp40/Hsp70 family, and we found that heat shock-induced TDP-43 aggregation is mediated by the availability of these chaperones interacting with the inherently disordered C-terminal prion domain. Finally, we observed that the aggregation of TDP-43 during heat shock led to decreased binding to hnRNPA1, and a change in TDP-43 RNA-binding partners suggesting that TDP-43 aggregation alters its function in response to misfolded protein stress. These findings indicate that TDP-43 shares properties with physiologic prions from yeast, in that self-aggregation is mediated by a Q/N-rich disordered domain, is modulated by chaperone proteins and leads to altered function of the protein. Furthermore, they indicate that TDP-43 aggregation is regulated by chaperone availability, explaining the recurrent observation of TDP-43 aggregates in degenerative diseases of both the brain and muscle where protein homeostasis is disrupted.
Collapse
Affiliation(s)
- Maria Udan-Johns
- Department of Neurology, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA
| | | | | | | | | | | | | | | |
Collapse
|