1
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Bartolomé-Nafría A, García-Pardo J, Ventura S. Mutations in human prion-like domains: pathogenic but not always amyloidogenic. Prion 2024; 18:28-39. [PMID: 38512820 PMCID: PMC10962614 DOI: 10.1080/19336896.2024.2329186] [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: 01/08/2024] [Accepted: 03/06/2024] [Indexed: 03/23/2024] Open
Abstract
Heterogeneous nuclear ribonucleoproteins (hnRNPs) are multifunctional proteins with integral roles in RNA metabolism and the regulation of alternative splicing. These proteins typically contain prion-like domains of low complexity (PrLDs or LCDs) that govern their assembly into either functional or pathological amyloid fibrils. To date, over 60 mutations targeting the LCDs of hnRNPs have been identified and associated with a spectrum of neurodegenerative diseases including amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and Alzheimer's disease (AD). The cryo-EM structures of pathological and functional fibrils formed by different hnRNPs have been recently elucidated, including those of hnRNPA1, hnRNPA2, hnRNPDL-2, TDP-43, and FUS. In this review, we discuss the structural features of these amyloid assemblies, placing particular emphasis on scrutinizing the impact of prevalent disease-associated mutations mapping within their LCDs. By performing systematic energy calculations, we reveal a prevailing trend of destabilizing effects induced by these mutations in the amyloid structure, challenging the traditionally assumed correlation between pathogenicity and amyloidogenic propensity. Understanding the molecular basis of this discrepancy might provide insights for developing targeted therapeutic strategies to combat hnRNP-associated diseases.
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Affiliation(s)
- Andrea Bartolomé-Nafría
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Javier García-Pardo
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Barcelona, Spain
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2
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Song J. Molecular Mechanisms of Phase Separation and Amyloidosis of ALS/FTD-linked FUS and TDP-43. Aging Dis 2024; 15:2084-2112. [PMID: 38029395 DOI: 10.14336/ad.2023.1118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Accepted: 11/18/2023] [Indexed: 12/01/2023] Open
Abstract
FUS and TDP-43, two RNA-binding proteins from the heterogeneous nuclear ribonucleoprotein family, have gained significant attention in the field of neurodegenerative diseases due to their association with amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD). They possess folded domains for binding ATP and various nucleic acids including DNA and RNA, as well as substantial intrinsically disordered regions (IDRs) including prion-like domains (PLDs) and RG-/RGG-rich regions. They play vital roles in various cellular processes, including transcription, splicing, microRNA maturation, RNA stability and transport and DNA repair. In particular, they are key components for forming ribonucleoprotein granules and stress granules (SGs) through homotypic or heterotypic liquid-liquid phase separation (LLPS). Strikingly, liquid-like droplets formed by FUS and TDP-43 may undergo aging to transform into less dynamic assemblies such as hydrogels, inclusions, and amyloid fibrils, which are the pathological hallmarks of ALS and FTD. This review aims to synthesize and consolidate the biophysical knowledge of the sequences, structures, stability, dynamics, and inter-domain interactions of FUS and TDP-43 domains, so as to shed light on the molecular mechanisms underlying their liquid-liquid phase separation (LLPS) and amyloidosis. The review further delves into the mechanisms through which ALS-causing mutants of the well-folded hPFN1 disrupt the dynamics of LLPS of FUS prion-like domain, providing key insights into a potential mechanism for misfolding/aggregation-prone proteins to cause neurodegenerative diseases and aging by gain of functions. With better understanding of different biophysical aspects of FUS and TDP-43, the ultimate goal is to develop drugs targeting LLPS and amyloidosis, which could mediate protein homeostasis within cells and lead to new treatments for currently intractable diseases, particularly neurodegenerative diseases such as ALS, FTD and aging. However, the study of membrane-less organelles and condensates is still in its infancy and therefore the review also highlights key questions that require future investigation.
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3
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Zeng J, Tang Y, Dong X, Li F, Wei G. Influence of ALS-linked M337V mutation on the conformational ensembles of TDP-43 321-340 peptide monomer and dimer. Proteins 2024; 92:1059-1069. [PMID: 36841957 DOI: 10.1002/prot.26482] [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: 01/09/2023] [Revised: 02/12/2023] [Accepted: 02/19/2023] [Indexed: 02/27/2023]
Abstract
The transactive response (TAR) DNA/RNA-binding protein 43 (TDP-43) can self-assemble into both functional stress granules via liquid-liquid phase separation (LLPS) and pathogenic amyloid fibrillary aggregates that are closely linked to amyotrophic lateral sclerosis. Previous experimental studies reported that the low complexity domain (LCD) of TDP-43 plays an essential role in the LLPS and aggregation of the full-length protein, and it alone can also undergo LLPS to form liquid droplets mainly via intermolecular interactions in the 321-340 region. And the ALS-associated M337V mutation impairs LCD's LLPS and facilitates liquid-solid phase transition. However, the underlying atomistic mechanism is not well understood. Herein, as a first step to understand the M337V-caused LLPS disruption of TDP-43 LCD mediated by the 321-340 region and the fibrillization enhancement, we investigated the conformational properties of monomer/dimer of TDP-43321-340 peptide and its M337V mutant by performing extensive all-atom explicit-solvent replica exchange molecular dynamic simulations. Our simulations demonstrate that M337V mutation alters the residue regions with high helix/β-structure propensities and thus affects the conformational ensembles of both monomer and dimer. M337V mutation inhibits helix formation in the N-terminal Ala-rich region and the C-terminal mutation site region, while facilitating their long β-sheet formation, albeit with a minor impact on the average probability of both helix structure and β-structure. Further analysis of dimer system shows that M337V mutation disrupts inter-molecular helix-helix interactions and W334-W334 π-π stacking interactions which were reported to be important for the LLPS of TDP-43 LCD, whereas enhances the overall peptide residue-residue interactions and weakens peptide-water interactions, which is conducive to peptide fibrillization. This study provides mechanistic insights into the M337V-mutation-induced impairment of phase separation and facilitation of fibril formation of TDP-43 LCD.
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Affiliation(s)
- Jiyuan Zeng
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Xuewei Dong
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou, Jiangsu, China
| | - Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai, China
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4
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Min JH, Sarlus H, Harris RA. Copper toxicity and deficiency: the vicious cycle at the core of protein aggregation in ALS. Front Mol Neurosci 2024; 17:1408159. [PMID: 39050823 PMCID: PMC11267976 DOI: 10.3389/fnmol.2024.1408159] [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: 03/27/2024] [Accepted: 06/14/2024] [Indexed: 07/27/2024] Open
Abstract
The pathophysiology of ALS involves many signs of a disruption in copper homeostasis, with both excess free levels and functional deficiency likely occurring simultaneously. This is crucial, as many important physiological functions are performed by cuproenzymes. While it is unsurprising that many ALS symptoms are related to signs of copper deficiency, resulting in vascular, antioxidant system and mitochondrial oxidative respiration deficiencies, there are also signs of copper toxicity such as ROS generation and enhanced protein aggregation. We discuss how copper also plays a key role in proteostasis and interacts either directly or indirectly with many of the key aggregate-prone proteins implicated in ALS, such as TDP-43, C9ORF72, SOD1 and FUS as well as the effect of their aggregation on copper homeostasis. We suggest that loss of cuproprotein function is at the core of ALS pathology, a condition that is driven by a combination of unbound copper and ROS that can either initiate and/or accelerate protein aggregation. This could trigger a positive feedback cycle whereby protein aggregates trigger the aggregation of other proteins in a chain reaction that eventually captures elements of the proteostatic mechanisms in place to counteract them. The end result is an abundance of aggregated non-functional cuproproteins and chaperones alongside depleted intracellular copper stores, resulting in a general lack of cuproenzyme function. We then discuss the possible aetiology of ALS and illustrate how strong risk factors including environmental toxins such as BMAA and heavy metals can functionally behave to promote protein aggregation and disturb copper metabolism that likely drives this vicious cycle in sporadic ALS. From this synthesis, we propose restoration of copper balance using copper delivery agents in combination with chaperones/chaperone mimetics, perhaps in conjunction with the neuroprotective amino acid serine, as a promising strategy in the treatment of this incurable disease.
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Affiliation(s)
- Jin-Hong Min
- Department of Clinical Neuroscience, Karolinska Institutet, Center for Molecular Medicine, Karolinska University Hospital at Solna, Stockholm, Sweden
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5
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Gao Y, Xu SM, Cheng Y, Takenaka K, Lindner G, Janitz M. Investigation of the Circular Transcriptome in Alzheimer's Disease Brain. J Mol Neurosci 2024; 74:64. [PMID: 38981928 PMCID: PMC11233389 DOI: 10.1007/s12031-024-02236-0] [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: 03/15/2024] [Accepted: 06/10/2024] [Indexed: 07/11/2024]
Abstract
Circular RNAs (circRNAs) are a subclass of non-coding RNAs which have demonstrated potential as biomarkers for Alzheimer's disease (AD). In this study, we conducted a comprehensive exploration of the circRNA transcriptome within AD brain tissues. Specifically, we assessed circRNA expression patterns in the dorsolateral prefrontal cortex collected from nine AD-afflicted individuals and eight healthy controls. Utilising two circRNA detection tools, CIRI2 and CIRCexplorer2, we detected thousands of circRNAs and performed a differential expression analysis. CircRNAs which exhibited statistically significantly differential expression were identified as AD-specific differentially expressed circRNAs. Notably, our investigation revealed 120 circRNAs with significant upregulation and 1325 circRNAs displaying significant downregulation in AD brains when compared to healthy brain tissue. Additionally, we explored the expression profiles of the linear RNA counterparts corresponding to differentially expressed circRNAs in AD-afflicted brains and discovered that the linear RNA counterparts exhibited no significant changes in the levels of expression. We used CRAFT tool to predict that circUBE4B had potential to target miRNA named as hsa-miR-325-5p, ultimately regulated CD44 gene. This study provides a comprehensive overview of differentially expressed circRNAs in the context of AD brains, underscoring their potential as molecular biomarkers for AD. These findings significantly enhance our comprehension of AD's underlying pathophysiological mechanisms, offering promising avenues for future diagnostic and therapeutic developments.
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Affiliation(s)
- Yulan Gao
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Si-Mei Xu
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Yuning Cheng
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Konii Takenaka
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Grace Lindner
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Michael Janitz
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia.
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6
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Rizuan A, Shenoy J, Mohanty P, dos Passos PMS, Mercado Ortiz JF, Bai L, Viswanathan R, Wang SH, Johnson V, Mamede LD, Ayala YM, Ghirlando R, Mittal J, Fawzi NL. Structural details of helix-mediated TDP-43 C-terminal domain multimerization. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.05.602258. [PMID: 39005345 PMCID: PMC11245101 DOI: 10.1101/2024.07.05.602258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 07/16/2024]
Abstract
The primarily disordered C-terminal domain (CTD) of TAR DNA binding protein-43 (TDP-43), a key nuclear protein in RNA metabolism, forms neuronal inclusions in several neurodegenerative diseases. A conserved region (CR, spanning residues 319-341) in CTD forms transient helix-helix contacts important for its higher-order oligomerization and function that are disrupted by ALS-associated mutations. However, the structural details of CR assembly and the explanation for several ALS-associated variants' impact on phase separation and function remain unclear due to challenges in analyzing the dynamic association of TDP-43 CTD using traditional structural biology approaches. By employing an integrative approach, combining biophysical experiments, biochemical assays, AlphaFold2-Multimer (AF2-Multimer), and atomistic simulations, we generated structural models of helical oligomerization of TDP-43 CR. Using NMR, we first established that the native state of TDP-43 CR under physiological conditions is α-helical. Next, alanine scanning mutagenesis revealed that while hydrophobic residues in the CR are important for CR assembly, phase separation and TDP-43 nuclear retention function, polar residues down regulate these processes. Finally, pairing AF2-Multimer modeling with AAMD simulations indicated that dynamic, oligomeric assemblies of TDP-43 that are stabilized by a methionine-rich core with specific contributions from a tryptophan/leucine pair. In conclusion, our results advance the structural understanding of the mechanisms driving TDP-43 function and provide a window into the initial stages of its conversion into pathogenic aggregates.
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Affiliation(s)
- Azamat Rizuan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843
| | - Jayakrishna Shenoy
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Priyesh Mohanty
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843
| | - Patricia M. S. dos Passos
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - José F. Mercado Ortiz
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Leanna Bai
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Renjith Viswanathan
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Szu-Huan Wang
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Victoria Johnson
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
| | - Lohany D. Mamede
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Yuna M. Ayala
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri
| | - Rodolfo Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843
- Department of Chemistry, Texas A&M University, College Station, TX 77843
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, TX 77843
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI 02912
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7
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Yan X, Kuster D, Mohanty P, Nijssen J, Pombo-García K, Rizuan A, Franzmann TM, Sergeeva A, Passos PM, George L, Wang SH, Shenoy J, Danielson HL, Honigmann A, Ayala YM, Fawzi NL, Mittal J, Alberti S, Hyman AA. Intra-condensate demixing of TDP-43 inside stress granules generates pathological aggregates. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.23.576837. [PMID: 38328053 PMCID: PMC10849624 DOI: 10.1101/2024.01.23.576837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Cytosolic aggregation of the nuclear protein TDP-43 is associated with many neurodegenerative diseases, but the triggers for TDP-43 aggregation are still debated. Here, we demonstrate that TDP-43 aggregation requires a double event. One is up-concentration in stress granules beyond a threshold, and the other is oxidative stress. These two events collectively induce intra-condensate demixing, giving rise to a dynamic TDP-43 enriched phase within stress granules, which subsequently transitions into pathological aggregates. Mechanistically, intra-condensate demixing is triggered by local unfolding of the RRM1 domain for intermolecular disulfide bond formation and by increased hydrophobic patch interactions in the C-terminal domain. By engineering TDP-43 variants resistant to intra-condensate demixing, we successfully eliminate pathological TDP-43 aggregates in cells. We conclude that up-concentration inside condensates and simultaneous exposure to environmental stress could be a general pathway for protein aggregation, with intra-condensate demixing constituting a key intermediate step.
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Affiliation(s)
- Xiao Yan
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
| | - David Kuster
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Priyesh Mohanty
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
- These authors contributed equally
| | - Jik Nijssen
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Karina Pombo-García
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- These authors contributed equally
| | - Azamat Rizuan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
| | - Titus M. Franzmann
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Aleksandra Sergeeva
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Patricia M. Passos
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Leah George
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Szu-Huan Wang
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Jayakrishna Shenoy
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Helen L. Danielson
- Center for Biomedical Engineering, Brown University; Providence, RI 02912; USA
| | - Alf Honigmann
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Yuna M. Ayala
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University; St. Louis, MO 63104; USA
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University; Providence, RI 02912; USA
| | - Jeetain Mittal
- Artie McFerrin Department of Chemical Engineering, Texas A&M University; College Station, TX 77843; USA
- Department of Chemistry, Texas A&M University; College Station, TX 77843; USA
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University; College Station, TX 77843; USA
| | - Simon Alberti
- Biotechnology Center (BIOTEC), Center for Molecular and Cellular Bioengineering, Technische Universität Dresden; Dresden, Saxony, 01307; Germany
| | - Anthony A. Hyman
- Max Planck Institute of Molecular Cell Biology and Genetics (MPI-CBG); Dresden, Saxony, 01307; Germany
- Lead contact
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8
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Song J. Adenosine Triphosphate: The Primordial Molecule That Controls Protein Homeostasis and Shapes the Genome-Proteome Interface. Biomolecules 2024; 14:500. [PMID: 38672516 PMCID: PMC11048592 DOI: 10.3390/biom14040500] [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: 03/29/2024] [Revised: 04/15/2024] [Accepted: 04/17/2024] [Indexed: 04/28/2024] Open
Abstract
Adenosine triphosphate (ATP) acts as the universal energy currency that drives various biological processes, while nucleic acids function to store and transmit genetic information for all living organisms. Liquid-liquid phase separation (LLPS) represents the common principle for the formation of membrane-less organelles (MLOs) composed of proteins rich in intrinsically disordered regions (IDRs) and nucleic acids. Currently, while IDRs are well recognized to facilitate LLPS through dynamic and multivalent interactions, the precise mechanisms by which ATP and nucleic acids affect LLPS still remain elusive. This review summarizes recent NMR results on the LLPS of human FUS, TDP-43, and the viral nucleocapsid (N) protein of SARS-CoV-2, as modulated by ATP and nucleic acids, revealing the following: (1) ATP binds to folded domains overlapping with nucleic-acid-binding interfaces; (2) ATP and nucleic acids interplay to biphasically modulate LLPS by competitively binding to overlapping pockets of folded domains and Arg/Lys within IDRs; (3) ATP energy-independently induces protein folding with the highest efficiency known so far. As ATP likely emerged in the prebiotic monomeric world, while LLPS represents a pivotal mechanism to concentrate and compartmentalize rare molecules for forming primordial cells, ATP appears to control protein homeostasis and shape genome-proteome interfaces throughout the evolutionary trajectory, from prebiotic origins to modern cells.
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Affiliation(s)
- Jianxing Song
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore
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9
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Haider R, Penumutchu S, Boyko S, Surewicz WK. Phosphomimetic substitutions in TDP-43's transiently α-helical region suppress phase separation. Biophys J 2024; 123:361-373. [PMID: 38178578 PMCID: PMC10870169 DOI: 10.1016/j.bpj.2024.01.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 11/10/2023] [Accepted: 01/02/2024] [Indexed: 01/06/2024] Open
Abstract
Phosphorylated TAR DNA-binding protein of 43 kDa (TDP-43) is present within the aggregates of several age-related neurodegenerative disorders, such as amyotrophic lateral sclerosis, frontotemporal lobar degeneration, and Alzheimer's disease, to the point that the presence of phosphorylated TDP-43 is considered a hallmark of some of these diseases. The majority of known TDP-43 phosphorylation sites detected in amyotrophic lateral sclerosis and frontotemporal lobar degeneration patients is located in the low-complexity domain (LCD), the same domain that has been shown to be critical for TDP-43 liquid-liquid phase separation (LLPS). However, the effect of these LCD phosphorylation sites on TDP-43 LLPS has been largely unexplored, and any work that has been done has mainly focused on sites near the C-terminal end of the LCD. Here, we used a phosphomimetic approach to explore the impact of phosphorylation at residues S332 and S333, sites located within the transiently α-helical region of TDP-43 that have been observed to be phosphorylated in disease, on protein LLPS. Our turbidimetry and fluorescence microscopy data demonstrate that these phosphomimetic substitutions greatly suppress LLPS, and solution NMR data strongly suggest that this effect is at least in part due to the loss of α-helical propensity of the phosphomimetic protein variant. We also show that the S332D and S333D substitutions slow TDP-43 LCD droplet aging and fibrillation of the protein. Overall, these findings provide a biophysical basis for understanding the effect of phosphorylation within the transiently α-helical region of TDP-43 LCD on protein LLPS and fibrillation, suggesting that phosphorylation at residues 332 and 333 is not necessarily directly related to the pathogenic process.
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Affiliation(s)
- Raza Haider
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
| | - Srinivasa Penumutchu
- Northeast Ohio High Field NMR Facility, Case Western Reserve University, Cleveland, Ohio
| | - Solomiia Boyko
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio
| | - Witold K Surewicz
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio.
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10
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Dos Passos PM, Hemamali EH, Mamede LD, Hayes LR, Ayala YM. RNA-mediated ribonucleoprotein assembly controls TDP-43 nuclear retention. PLoS Biol 2024; 22:e3002527. [PMID: 38422113 DOI: 10.1371/journal.pbio.3002527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Revised: 03/12/2024] [Accepted: 01/29/2024] [Indexed: 03/02/2024] Open
Abstract
TDP-43 is an essential RNA-binding protein strongly implicated in the pathogenesis of neurodegenerative disorders characterized by cytoplasmic aggregates and loss of nuclear TDP-43. The protein shuttles between nucleus and cytoplasm, yet maintaining predominantly nuclear TDP-43 localization is important for TDP-43 function and for inhibiting cytoplasmic aggregation. We previously demonstrated that specific RNA binding mediates TDP-43 self-assembly and biomolecular condensation, requiring multivalent interactions via N- and C-terminal domains. Here, we show that these complexes play a key role in TDP-43 nuclear retention. TDP-43 forms macromolecular complexes with a wide range of size distribution in cells and we find that defects in RNA binding or inter-domain interactions, including phase separation, impair the assembly of the largest species. Our findings suggest that recruitment into these macromolecular complexes prevents cytoplasmic egress of TDP-43 in a size-dependent manner. Our observations uncover fundamental mechanisms controlling TDP-43 cellular homeostasis, whereby regulation of RNA-mediated self-assembly modulates TDP-43 nucleocytoplasmic distribution. Moreover, these findings highlight pathways that may be implicated in TDP-43 proteinopathies and identify potential therapeutic targets.
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Affiliation(s)
- Patricia M Dos Passos
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Erandika H Hemamali
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Lohany D Mamede
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
| | - Lindsey R Hayes
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States of America
| | - Yuna M Ayala
- Edward Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, United States of America
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11
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Garcia-Pardo J, Ventura S. Cryo-EM structures of functional and pathological amyloid ribonucleoprotein assemblies. Trends Biochem Sci 2024; 49:119-133. [PMID: 37926650 DOI: 10.1016/j.tibs.2023.10.005] [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: 07/26/2023] [Revised: 10/05/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023]
Abstract
Amyloids are implicated in neurodegenerative and systemic diseases, yet they serve important functional roles in numerous organisms. Heterogeneous nuclear ribonucleoproteins (hnRNPs) represent a large family of RNA-binding proteins (RBPs) that control central events of RNA biogenesis in normal and diseased cellular conditions. Many of these proteins contain prion-like sequences of low complexity, which not only assemble into functional fibrils in response to cellular cues but can also lead to disease when missense mutations arise in their sequences. Recent advances in cryo-electron microscopy (cryo-EM) have provided unprecedented high-resolution structural insights into diverse amyloid assemblies formed by hnRNPs and structurally related RBPs, including TAR DNA-binding protein 43 (TDP-43), Fused in Sarcoma (FUS), Orb2, hnRNPA1, hnRNPA2, and hnRNPDL-2. This review provides a comprehensive overview of these structures and explores their functional and pathological implications.
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Affiliation(s)
- Javier Garcia-Pardo
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
| | - Salvador Ventura
- Institut de Biotecnologia i de Biomedicina (IBB) and Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, 08193, Bellaterra, Barcelona, Spain.
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12
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Cascella R, Banchelli M, Abolghasem Ghadami S, Ami D, Gagliani MC, Bigi A, Staderini T, Tampellini D, Cortese K, Cecchi C, Natalello A, Adibi H, Matteini P, Chiti F. An in situ and in vitro investigation of cytoplasmic TDP-43 inclusions reveals the absence of a clear amyloid signature. Ann Med 2023; 55:72-88. [PMID: 36495262 PMCID: PMC9746631 DOI: 10.1080/07853890.2022.2148734] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Introduction: Several neurodegenerative conditions are associated with a common histopathology within neurons of the central nervous system, consisting of the deposition of cytoplasmic inclusions of TAR DNA-binding protein 43 (TDP-43). Such inclusions have variably been described as morphologically and molecularly ordered aggregates having amyloid properties, as filaments without the cross-β-structure and dye binding specific for amyloid, or as amorphous aggregates with no defined structure and fibrillar morphology.Aims and Methods: Here we have expressed human full-length TDP-43 in neuroblastoma x spinal cord 34 (NSC-34) cells to investigate the morphological, structural, and tinctorial properties of TDP-43 inclusions in situ. We have used last-generation amyloid diagnostic probes able to cross the cell membrane and detect amyloid in the cytoplasm and have adopted Raman and Fourier transform infrared microspectroscopies to study in situ the secondary structure of the TDP-43 protein in the inclusions. We have then used transmission electron microscopy to study the morphology of the TDP-43 inclusions.Results: The results show the absence of amyloid dye binding, the lack of an enrichment of cross-β structure in the inclusions, and of a fibrillar texture in the round inclusions. The aggregates formed in vitro from the purified protein under conditions in which it is initially native also lack all these characteristics, ruling out a clear amyloid-like signature.Conclusions: These findings indicate a low propensity of TDP-43 to form amyloid fibrils and even non-amyloid filaments, under conditions in which the protein is initially native and undergoes its typical nucleus-to-cell mislocalization. It cannot be excluded that filaments emerge on the long time scale from such inclusions, but the high propensity of the protein to form initially other types of inclusions appear to be an essential characteristic of TDP-43 proteinopathies.KEY MESSAGESCytoplasmic inclusions of TDP-43 formed in NSC-34 cells do not stain with amyloid-diagnostic dyes, are not enriched with cross-β structure, and do not show a fibrillar morphology.TDP-43 assemblies formed in vitro from pure TDP-43 do not have any hallmarks of amyloid.
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Affiliation(s)
- Roberta Cascella
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Martina Banchelli
- Institute of Applied Physics "Nello Carrara", National Research Council, Sesto Fiorentino, Italy
| | | | - Diletta Ami
- Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.,Milan Center of Neuroscience (NeuroMI), Milan, Italy
| | - Maria Cristina Gagliani
- Cellular Electron Microscopy Laboratory, Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Alessandra Bigi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Tommaso Staderini
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Davide Tampellini
- U 1195 INSERM-Université Paris-Saclay, Paris, France.,Institut Professeur Baulieu, Paris, France
| | - Katia Cortese
- Cellular Electron Microscopy Laboratory, Department of Experimental Medicine, University of Genova, Genoa, Italy
| | - Cristina Cecchi
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
| | - Antonino Natalello
- Department of Biotechnologies and Biosciences, University of Milano-Bicocca, Milan, Italy.,Milan Center of Neuroscience (NeuroMI), Milan, Italy
| | - Hadi Adibi
- Pharmaceutical Sciences Research Center, Health Institute, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Paolo Matteini
- Institute of Applied Physics "Nello Carrara", National Research Council, Sesto Fiorentino, Italy
| | - Fabrizio Chiti
- Department of Experimental and Clinical Biomedical Sciences "Mario Serio", University of Florence, Florence, Italy
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13
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Lim L, Kang J, Song J. Extreme diversity of 12 cations in folding ALS-linked hSOD1 unveils novel hSOD1-dependent mechanisms for Fe 2+/Cu 2+-induced cytotoxicity. Sci Rep 2023; 13:19868. [PMID: 37964005 PMCID: PMC10645853 DOI: 10.1038/s41598-023-47338-8] [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: 09/04/2023] [Accepted: 11/12/2023] [Indexed: 11/16/2023] Open
Abstract
153-Residue copper-zinc superoxide dismutase 1 (hSOD1) is the first gene whose mutation was linked to FALS. To date, > 180 ALS-causing mutations have been identified within hSOD1, yet the underlying mechanism still remains mysterious. Mature hSOD1 is exceptionally stable constrained by a disulfide bridge to adopt a Greek-key β-barrel fold that accommodates copper/zinc cofactors. Conversely, nascent hSOD1 is unfolded and susceptible to aggregation and amyloid formation, requiring Zn2+ to initiate folding to a coexistence of folded and unfolded states. Recent studies demonstrate mutations that disrupt Zn2+-binding correlate with their ability to form toxic aggregates. Therefore, to decode the role of cations in hSOD1 folding provides not only mechanistic insights, but may bear therapeutic implications for hSOD1-linked ALS. Here by NMR, we visualized the effect of 12 cations: 8 essential for humans (Na+, K+, Ca2+, Zn2+, Mg2+, Mn2+, Cu2+, Fe2+), 3 mimicking zinc (Ni2+, Cd2+, Co2+), and environmentally abundant Al3+. Surprisingly, most cations, including Zn2+-mimics, showed negligible binding or induction for folding of nascent hSOD1. Cu2+ exhibited extensive binding to the unfolded state but led to severe aggregation. Unexpectedly, for the first time Fe2+ was deciphered to have Zn2+-like folding-inducing capacity. Zn2+ was unable to induce folding of H80S/D83S-hSOD1, while Fe2+ could. In contrast, Zn2+ could trigger folding of G93A-hSOD1, but Fe2+ failed. Notably, pre-existing Fe2+ disrupted the Zn2+-induced folding of G93A-hSOD1. Comparing with the ATP-induced folded state, our findings delineate that hSOD1 maturation requires: (1) intrinsic folding capacity encoded by the sequence; (2) specific Zn2+-coordination; (3) disulfide formation and Cu-load catalyzed by hCCS. This study unveils a previously-unknown interplay of cations in governing the initial folding of hSOD1, emphasizing the pivotal role of Zn2+ in hSOD1-related ALS and implying new hSOD1-dependent mechanisms for Cu2+/Fe2+-induced cytotoxicity, likely relevant to aging and other diseases.
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Affiliation(s)
- Liangzhong Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 119260, Republic of Singapore
| | - Jian Kang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 119260, Republic of Singapore
| | - Jianxing Song
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore, 119260, Republic of Singapore.
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14
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Gu J, Zhou X, Sutherland L, Kato M, Jaczynska K, Rizo J, McKnight SL. Oxidative regulation of TDP-43 self-association by a β-to-α conformational switch. Proc Natl Acad Sci U S A 2023; 120:e2311416120. [PMID: 37782781 PMCID: PMC10576115 DOI: 10.1073/pnas.2311416120] [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: 07/10/2023] [Accepted: 09/04/2023] [Indexed: 10/04/2023] Open
Abstract
An evolutionarily conserved region of the TDP-43 low-complexity domain (LCD) twenty residues in length can adopt either an α-helical or β-strand conformation. When in the latter conformation, TDP-43 self-associates via the formation of a labile, cross-β structure. Self-association can be monitored via the formation of phase-separated protein droplets. Exposure of droplets to hydrogen peroxide leads to oxidation of conserved methionine residues distributed throughout the LCD. Oxidation disassembles the cross-β structure, thus eliminating both self-association and phase separation. Here, we demonstrate that this process reciprocally enables formation of α-helical structure in precisely the same region formerly functioning to facilitate β-strand-mediated self-association. We further observe that the α-helical conformation allows interaction with a lipid-like detergent and that exposure to lipids enhances the β-to-α conformational switch. We hypothesize that regulation of this oxidative switch will prove to be important to the control of localized translation within vertebrate cells. The experimental observations reported herein were heavily reliant on studies of 1,6-hexanediol, a chemical agent that selectively dissolves labile structures formed via the self-association of protein domains of low sequence complexity. This aliphatic alcohol is shown to exert its dissociative activity primarily via hydrogen-bonding interactions with carbonyl oxygen atoms of the polypeptide backbone. Such observations underscore the central importance of backbone-mediated protein:protein interactions that facilitate the self-association and phase separation of LCDs.
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Affiliation(s)
- Jinge Gu
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX75235
| | - Xiaoming Zhou
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX75235
| | - Lillian Sutherland
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX75235
| | - Masato Kato
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX75235
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology, Inage-ku, Chiba263-8555, Japan
| | - Klaudia Jaczynska
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX75235
| | - Josep Rizo
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX75235
| | - Steven L. McKnight
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX75235
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15
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Gu J, Zhou X, Sutherland L, Kato M, Jaczynska K, Rizo J, McKnight SL. Oxidative regulation of TDP-43 self-association by a β-to-α conformational switch. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.29.555361. [PMID: 37693418 PMCID: PMC10491227 DOI: 10.1101/2023.08.29.555361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
An evolutionarily conserved region of the TDP-43 low complexity domain twenty residues in length can adopt either an α-helical or β-strand conformation. When in the latter conformation, TDP-43 self-associates via the formation of a labile, cross-β structure. Self-association can be monitored via the formation of phase separated protein droplets. Exposure of droplets to hydrogen peroxide leads to oxidation of conserved methionine residues distributed throughout the low complexity domain. Oxidation disassembles the cross-β structure, thus eliminating both self-association and phase separation. Here we demonstrate that this process reciprocally enables formation of α-helical structure in precisely the same region formerly functioning to facilitate β-strand mediated self-association. We further observe that the α-helical conformation allows interaction with a lipid-like detergent, and that exposure to lipids enhances the β-to-α conformational switch. We hypothesize that regulation of this oxidative switch will prove to be important to the control of localized translation within vertebrate cells. The experimental observations reported herein were heavily reliant on studies of 1,6-hexanediol, a chemical agent that selectively dissolves labile structures formed via the self-association of protein domains of low sequence complexity. This aliphatic alcohol is shown to exert its dissociative activity primarily via hydrogen bonding interactions with carbonyl oxygen atoms of the polypeptide backbone. Such observations underscore the central importance of backbone-mediated protein:protein interactions that facilitate the self-association and phase separation of low complexity domains. Significance Statement The TDP-43 protein is a constituent of RNA granules involved in regulated translation. TDP-43 contains a C-terminal domain of 150 amino acids of low sequence complexity conspicuously decorated with ten methionine residues. An evolutionarily conserved region (ECR) of 20 residues within this domain can adopt either of two forms of labile secondary structure. Under normal conditions wherein methionine residues are reduced, the ECR forms a labile cross-β structure that enables RNA granule condensation. Upon methionine oxidation, the ECR undergoes a conformational switch to become an α-helix incompatible with self-association and granule integrity. Oxidation of the TDP-43 low complexity domain is hypothesized to occur proximal to mitochondria, thus facilitating dissolution of RNA granules and activation of localized translation.
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Affiliation(s)
- Jinge Gu
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
| | - Xiaoming Zhou
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
| | - Lillian Sutherland
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
| | - Masato Kato
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
- Institute for Quantum Life Science, National Institutes for Quantum Science and Technology (QST) 4-9-1, Anagawa, Inage-ku, Chiba, JAPAN 263-8555
| | - Klaudia Jaczynska
- Department of Biophysics, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
| | - Josep Rizo
- Department of Biophysics, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
| | - Steven L. McKnight
- Department of Biochemistry, UT Southwestern Medical Center 5323 Harry Hines Blvd., Dallas, Texas 75235
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16
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Mohanty P, Shenoy J, Rizuan A, Mercado-Ortiz JF, Fawzi NL, Mittal J. A synergy between site-specific and transient interactions drives the phase separation of a disordered, low-complexity domain. Proc Natl Acad Sci U S A 2023; 120:e2305625120. [PMID: 37579155 PMCID: PMC10450430 DOI: 10.1073/pnas.2305625120] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/17/2023] [Indexed: 08/16/2023] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is involved in key processes in RNA metabolism and is frequently implicated in many neurodegenerative diseases, including amyotrophic lateral sclerosis and frontotemporal dementia. The prion-like, disordered C-terminal domain (CTD) of TDP-43 is aggregation-prone, can undergo liquid-liquid phase separation (LLPS) in isolation, and is critical for phase separation (PS) of the full-length protein under physiological conditions. While a short conserved helical region (CR, spanning residues 319-341) promotes oligomerization and is essential for LLPS, aromatic residues in the flanking disordered regions (QN-rich, IDR1/2) are also found to play a critical role in PS and aggregation. Compared with other phase-separating proteins, TDP-43 CTD has a notably distinct sequence composition including many aliphatic residues such as methionine and leucine. Aliphatic residues were previously suggested to modulate the apparent viscosity of the resulting phases, but their direct contribution toward CTD phase separation has been relatively ignored. Using multiscale simulations coupled with in vitro saturation concentration (csat) measurements, we identified the importance of aromatic residues while also suggesting an essential role for aliphatic methionine residues in promoting single-chain compaction and LLPS. Surprisingly, NMR experiments showed that transient interactions involving phenylalanine and methionine residues in the disordered flanking regions can directly enhance site-specific, CR-mediated intermolecular association. Overall, our work highlights an underappreciated mode of biomolecular recognition, wherein both transient and site-specific hydrophobic interactions act synergistically to drive the oligomerization and phase separation of a disordered, low-complexity domain.
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Affiliation(s)
- Priyesh Mohanty
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
| | - Jayakrishna Shenoy
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Azamat Rizuan
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
| | - José F. Mercado-Ortiz
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Nicolas L. Fawzi
- Department of Molecular Biology, Cell Biology & Biochemistry, Brown University, Providence, RI02912
| | - Jeetain Mittal
- Artie McFerrinDepartment of Chemical Engineering, Texas A&M University, College Station, TX77843
- Department of Chemistry, Texas A&M University, College Station, TX77843
- Interdisciplinary Graduate Program in Genetics and Genomics, Texas A&M University, College Station, TX77843
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17
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Dos Passos PM, Hemamali EH, Mamede LD, Hayes LR, Ayala YM. RNA-mediated ribonucleoprotein assembly controls TDP-43 nuclear retention. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.06.552215. [PMID: 37609278 PMCID: PMC10441353 DOI: 10.1101/2023.08.06.552215] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
TDP-43 is an essential RNA-binding protein strongly implicated in the pathogenesis of neurodegenerative disorders characterized by cytoplasmic aggregates and loss of nuclear TDP-43. The protein shuttles between nucleus and cytoplasm, yet maintaining predominantly nuclear TDP-43 localization is important for TDP-43 function and for inhibiting cytoplasmic aggregation. We previously demonstrated that specific RNA binding mediates TDP-43 self-assembly and biomolecular condensation, requiring multivalent interactions via N- and C-terminal domains. Here, we show that these complexes play a key role in TDP-43 nuclear retention. TDP-43 forms macromolecular complexes with a wide range of size distribution in cells and we find that defects in RNA binding or inter-domain interactions, including phase separation, impair the assembly of the largest species. Our findings suggest that recruitment into these macromolecular complexes prevents cytoplasmic egress of TDP-43 in a size-dependent manner. Our observations uncover fundamental mechanisms controlling TDP-43 cellular homeostasis, whereby regulation of RNA-mediated self-assembly modulates TDP-43 nucleocytoplasmic distribution. Moreover, these findings highlight pathways that may be implicated in TDP-43 proteinopathies and identify potential therapeutic targets.
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18
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Bagyinszky E, Hulme J, An SSA. Studies of Genetic and Proteomic Risk Factors of Amyotrophic Lateral Sclerosis Inspire Biomarker Development and Gene Therapy. Cells 2023; 12:1948. [PMID: 37566027 PMCID: PMC10417729 DOI: 10.3390/cells12151948] [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: 06/21/2023] [Revised: 07/21/2023] [Accepted: 07/25/2023] [Indexed: 08/12/2023] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease affecting the upper and lower motor neurons, leading to muscle weakness, motor impairments, disabilities and death. Approximately 5-10% of ALS cases are associated with positive family history (familial ALS or fALS), whilst the remainder are sporadic (sporadic ALS, sALS). At least 50 genes have been identified as causative or risk factors for ALS. Established pathogenic variants include superoxide dismutase type 1 (SOD1), chromosome 9 open reading frame 72 (c9orf72), TAR DNA Binding Protein (TARDBP), and Fused In Sarcoma (FUS); additional ALS-related genes including Charged Multivesicular Body Protein 2B (CHMP2B), Senataxin (SETX), Sequestosome 1 (SQSTM1), TANK Binding Kinase 1 (TBK1) and NIMA Related Kinase 1 (NEK1), have been identified. Mutations in these genes could impair different mechanisms, including vesicle transport, autophagy, and cytoskeletal or mitochondrial functions. So far, there is no effective therapy against ALS. Thus, early diagnosis and disease risk predictions remain one of the best options against ALS symptomologies. Proteomic biomarkers, microRNAs, and extracellular vehicles (EVs) serve as promising tools for disease diagnosis or progression assessment. These markers are relatively easy to obtain from blood or cerebrospinal fluids and can be used to identify potential genetic causative and risk factors even in the preclinical stage before symptoms appear. In addition, antisense oligonucleotides and RNA gene therapies have successfully been employed against other diseases, such as childhood-onset spinal muscular atrophy (SMA), which could also give hope to ALS patients. Therefore, an effective gene and biomarker panel should be generated for potentially "at risk" individuals to provide timely interventions and better treatment outcomes for ALS patients as soon as possible.
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Affiliation(s)
- Eva Bagyinszky
- Graduate School of Environment Department of Industrial and Environmental Engineering, Gachon University, Seongnam-si 13120, Republic of Korea;
| | - John Hulme
- Graduate School of Environment Department of Industrial and Environmental Engineering, Gachon University, Seongnam-si 13120, Republic of Korea;
| | - Seong Soo A. An
- Department of Bionano Technology, Gachon University, Seongnam-si 13120, Republic of Korea
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19
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Li F, Chen Y, Tang Y, Liu X, Wei G. Dissecting the Effect of ALS Mutation G335D on the Early Aggregation of the TDP-43 Amyloidogenic Core Peptide: Helix-to-β-Sheet Transition and Conformational Shift. J Chem Inf Model 2023; 63:3579-3590. [PMID: 37218694 DOI: 10.1021/acs.jcim.3c00513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The aggregation of TAR DNA-binding protein of 43 kDa (TDP-43) into fibrillary deposits is associated with amyotrophic lateral sclerosis (ALS). The 311-360 fragment of TDP-43 (TDP-43311-360), the amyloidogenic core region, can spontaneously aggregate into fibrils, and the ALS-associated mutation G335D has an enhanced effect on TDP-43311-360 fibrillization. However, the molecular mechanism underlying G335D-enhanced aggregation at atomic level remains largely unknown. By utilizing all-atom molecular dynamics (MD) and replica exchange with solute tempering 2 (REST2) simulations, we investigated influences of G335D on the dimerization (the first step of aggregation) and conformational ensemble of the TDP-43311-360 peptide. Our simulations show that G335D mutation increases inter-peptide interactions, especially inter-peptide hydrogen-bonding interactions in which the mutant site has a relatively large contribution, and enhances the dimerization of TDP-43311-360 peptides. The α-helix regions in the NMR-resolved conformation of the TDP-43311-360 monomer (321-330 and 335-343) play an essential role in the formation of the dimer. G335D mutation induces helix unfolding and promotes α-to-β conversion. G335D mutation alters the conformational distribution of TDP-43311-360 dimers and causes population shift from helix-rich to β-sheet-rich conformations, which facilitates the fibrillization of the TDP-43311-360 peptide. Our MD and REST2 simulation results suggest that the 321-330 region is of paramount importance to α-to-β transition and could be the initiation site for TDP-43311-360 fibrillization. Our work reveals the mechanism underlying the enhanced aggregation propensity of the G335D TDP-43311-360 peptide, which provides atomistic insights into the G335D mutation-caused pathogenicity of TDP-43 protein.
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Affiliation(s)
- Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Yujie Chen
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Xianshi Liu
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
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20
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Kumar ST, Nazarov S, Porta S, Maharjan N, Cendrowska U, Kabani M, Finamore F, Xu Y, Lee VMY, Lashuel HA. Seeding the aggregation of TDP-43 requires post-fibrillization proteolytic cleavage. Nat Neurosci 2023:10.1038/s41593-023-01341-4. [PMID: 37248338 DOI: 10.1038/s41593-023-01341-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 04/18/2023] [Indexed: 05/31/2023]
Abstract
Despite the strong evidence linking the transactive response DNA-binding protein 43 (TDP-43) aggregation to the pathogenesis of frontotemporal lobar degeneration with TDP-43, amyotrophic lateral sclerosis and several neurodegenerative diseases, our knowledge of the sequence and structural determinants of its aggregation and neurotoxicity remains incomplete. Herein, we present a new method for producing recombinant full-length TDP-43 filaments that exhibit sequence and morphological features similar to those of brain-derived TDP-43 filaments. We show that TDP-43 filaments contain a β-sheet-rich helical amyloid core that is fully buried by the flanking structured domains of the protein. We demonstrate that the proteolytic cleavage of TDP-43 filaments and exposure of this amyloid core are necessary for propagating TDP-43 pathology and enhancing the seeding of brain-derived TDP-43 aggregates. Only TDP-43 filaments with exposed amyloid core efficiently seeded the aggregation of endogenous TDP-43 in cells. These findings suggest that inhibiting the enzymes mediating cleavage of TDP-43 aggregates represents a viable disease-modifying strategy to slow the progression of amyotrophic lateral sclerosis and other TDP-43 proteinopathies.
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Affiliation(s)
- Senthil T Kumar
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Sergey Nazarov
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Sílvia Porta
- Center for Neurodegenerative Disease Research (CNDR), Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Niran Maharjan
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Urszula Cendrowska
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Malek Kabani
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Francesco Finamore
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland
| | - Yan Xu
- Center for Neurodegenerative Disease Research (CNDR), Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Virginia M-Y Lee
- Center for Neurodegenerative Disease Research (CNDR), Department of Pathology and Laboratory Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Hilal A Lashuel
- Laboratory of Molecular and Chemical Biology of Neurodegeneration, Brain Mind Institute, EPFL, Lausanne, Switzerland.
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21
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Balasco N, Diaferia C, Rosa E, Monti A, Ruvo M, Doti N, Vitagliano L. A Comprehensive Analysis of the Intrinsic Visible Fluorescence Emitted by Peptide/Protein Amyloid-like Assemblies. Int J Mol Sci 2023; 24:ijms24098372. [PMID: 37176084 PMCID: PMC10178990 DOI: 10.3390/ijms24098372] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/15/2023] Open
Abstract
Amyloid aggregation is a widespread process that involves proteins and peptides with different molecular complexity and amino acid composition. The structural motif (cross-β) underlying this supramolecular organization generates aggregates endowed with special mechanical and spectroscopic properties with huge implications in biomedical and technological fields, including emerging precision medicine. The puzzling ability of these assemblies to emit intrinsic and label-free fluorescence in regions of the electromagnetic spectrum, such as visible and even infrared, usually considered to be forbidden in the polypeptide chain, has attracted interest for its many implications in both basic and applied science. Despite the interest in this phenomenon, the physical basis of its origin is still poorly understood. To gain a global view of the available information on this phenomenon, we here provide an exhaustive survey of the current literature in which original data on this fluorescence have been reported. The emitting systems have been classified in terms of their molecular complexity, amino acid composition, and physical state. Information about the wavelength of the radiation used for the excitation as well as the emission range/peak has also been retrieved. The data collected here provide a picture of the complexity of this multifaceted phenomenon that could be helpful for future studies aimed at defining its structural and electronic basis and/or stimulating new applications.
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Affiliation(s)
- Nicole Balasco
- Institute of Molecular Biology and Pathology, National Research Council (CNR), Department of Chemistry, University of Rome Sapienza, Piazzale Aldo Moro 5, 00185 Rome, Italy
| | - Carlo Diaferia
- Department of Pharmacy and CIRPeB, Research Centre on Bioactive Peptides "Carlo Pedone", University of Naples "Federico II", Via Montesano 49, 80131 Naples, Italy
| | - Elisabetta Rosa
- Department of Pharmacy and CIRPeB, Research Centre on Bioactive Peptides "Carlo Pedone", University of Naples "Federico II", Via Montesano 49, 80131 Naples, Italy
| | - Alessandra Monti
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Menotti Ruvo
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Nunzianna Doti
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging (IBB), National Research Council (CNR), 80131 Napoli, Italy
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22
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Kang J, Lim L, Song J. ALS-causing hPFN1 mutants differentially disrupt LLPS of FUS prion-like domain. Biochem Biophys Res Commun 2023; 664:35-42. [PMID: 37130459 DOI: 10.1016/j.bbrc.2023.04.101] [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: 04/03/2023] [Accepted: 04/27/2023] [Indexed: 05/04/2023]
Abstract
hPFN1 mutations including C71G cause ALS by gain of toxicity but the mechanism still remains unknown. Stress granules (SGs) are formed by phase separation of the prion-like domain (PLD) of RNA-binding proteins including FUS, whose inclusion was also associated with ALS. C71G-hPFN1 triggers seed-dependent co-aggregation with FUS/TDP-43 to manifest the prion-like propagandation but its biophysical basis remains unexplored. Here by DIC imaging we first showed that three hPFN1 mutants have differential capacity in disrupting the dynamics of liquid droplets formed by phase separation of FUS prion-like domain (PLD). C71G-hPFN1 co-exists with the folded and unfolded states, thus allowing to simultaneously characterize conformations, hydrodynamics and dynamics of the interactions of both states with the phase separated FUS PLD by NMR. The results reveal that the folded state is not significantly affected while by contrast, the unfolded state has extensive interactions with FUS PLD. As a consequence, the dynamics of FUS liquid droplets become significantly reduced. Such interactions might act to recruit C71G-hPFN1 into the droplets, thus leading to the increase of the local concentrations and subsequent co-aggregation of C71G-hPFN1 with FUS. Our study sheds the first light on the biophysical basis by which hPFN1 mutants gain toxicity to cause ALS. As other aggregation-prone proteins have no fundamental difference from hPFN1 mutants, aggregation-prone proteins might share a common capacity in disrupting phase separation responsible for organizing various membrane-less organelles. As such, the mechanism for C71G-hPFN1 might also be utilized by other aggregation-prone proteins for gain of toxicity to trigger diseases and aging.
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Affiliation(s)
- Jian Kang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore
| | - Liangzhong Lim
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore
| | - Jianxing Song
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore.
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23
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Liu X, Li X, Qiao Q, Li F, Wei G. ALS-Linked A315T and A315E Mutations Enhance β-Barrel Formation of the TDP-43 307-319 Hexamer: A REST2 Simulation Study. ACS Chem Neurosci 2023; 14:1310-1320. [PMID: 36888995 DOI: 10.1021/acschemneuro.3c00012] [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: 03/10/2023] Open
Abstract
Pathogenic mutations of transactivation response element DNA-binding protein 43 (TDP-43) are closely linked with amyotrophic lateral sclerosis (ALS). It was recently reported that two ALS-linked familial mutants A315T and A315E of TDP-43307-319 peptides can self-assemble into oligomers including tetramers, hexamers, and octamers, among which hexamers were suggested to form the β-barrel structure. However, due to the transient nature of oligomers, their conformational properties and the atomic mechanisms underlying the β-barrel formation remain largely elusive. Herein, we investigated the hexameric conformational distributions of the wild-type (WT) TDP-43307-319 fragment and its A315T and A315E mutants by performing all-atom explicit-solvent replica exchange with solute tempering 2 simulations. Our simulations reveal that each peptide can self-assemble into diverse conformations including ordered β-barrels, bilayer β-sheets and/or monolayer β-sheets, and disordered complexes. A315T and A315E mutants display higher propensity to form β-barrel structures than the WT, which provides atomic explanation for their enhanced neurotoxicity reported previously. Detailed interaction analysis shows that A315T and A315E mutations increase inter-molecular interactions. Also, the β-barrel structures formed by the three different peptides are stabilized by distinct inter-peptide side-chain hydrogen bonding, hydrophobic, and aromatic stacking interactions. This study demonstrates the enhanced β-barrel formation of the TDP-43307-319 hexamer by the pathogenic A315T and A315E mutations and reveals the underlying molecular determinants, which may be helpful for in-depth understanding of the ALS-mutation-induced neurotoxicity of TDP-43 protein.
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Affiliation(s)
- Xianshi Liu
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Xuhua Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, People's Republic of China
| | - Qin Qiao
- Digital Medical Research Center, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China.,Shanghai Key Laboratory of Medical Image Computing and Computer Assisted Intervention, Shanghai 200032, China
| | - Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, People's Republic of China
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24
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TDP-43 Proteinopathy Specific Biomarker Development. Cells 2023; 12:cells12040597. [PMID: 36831264 PMCID: PMC9954136 DOI: 10.3390/cells12040597] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Revised: 01/31/2023] [Accepted: 02/07/2023] [Indexed: 02/16/2023] Open
Abstract
TDP-43 is the primary or secondary pathological hallmark of neurodegenerative diseases, such as amyotrophic lateral sclerosis, half of frontotemporal dementia cases, and limbic age-related TDP-43 encephalopathy, which clinically resembles Alzheimer's dementia. In such diseases, a biomarker that can detect TDP-43 proteinopathy in life would help to stratify patients according to their definite diagnosis of pathology, rather than in clinical subgroups of uncertain pathology. For therapies developed to target pathological proteins that cause the disease a biomarker to detect and track the underlying pathology would greatly enhance such undertakings. This article reviews the latest developments and outlooks of deriving TDP-43-specific biomarkers from the pathophysiological processes involved in the development of TDP-43 proteinopathy and studies using biosamples from clinical entities associated with TDP-43 pathology to investigate biomarker candidates.
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25
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Dang M, Li T, Song J. ATP and nucleic acids competitively modulate LLPS of the SARS-CoV2 nucleocapsid protein. Commun Biol 2023; 6:80. [PMID: 36681763 PMCID: PMC9862227 DOI: 10.1038/s42003-023-04480-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Accepted: 01/13/2023] [Indexed: 01/22/2023] Open
Abstract
SARS-CoV-2 nucleocapsid (N) protein with very low mutation rates is the only structural protein which not only functions to package viral genomic RNA, but also manipulates host-cell machineries, thus representing a key target for drug development. Recent discovery of its liquid-liquid phase separation (LLPS) opens up a new direction for developing anti-SARS-CoV-2 strategies/drugs. However, so far the high-resolution mechanism of its LLPS still remains unknown. Here by DIC and NMR characterization, we have demonstrated: 1) nucleic acids modulate LLPS by dynamic and multivalent interactions over both folded NTD/CTD and Arg/Lys residues within IDRs; 2) ATP with concentrations > mM in all living cells but absent in viruses not only binds NTD/CTD, but also Arg residues within IDRs with a Kd of 2.8 mM; and 3) ATP dissolves nucleic-acid-induced LLPS by competitively displacing nucleic acid from binding the protein. Our study deciphers that the essential binding of N protein with nucleic acid and its LLPS are targetable by small molecules including ATP, which is emerging as a cellular factor controlling the host-SARS-CoV-2 interaction. Fundamentally, our results imply that the mechanisms of LLPS of IDR-containing proteins mediated by ATP and nucleic acids appear to be highly conserved from human to virus.
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Affiliation(s)
- Mei Dang
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore, Singapore
| | - Tongyang Li
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore, Singapore
| | - Jianxing Song
- Department of Biological Sciences, Faculty of Science, National University of Singapore, 10 Kent Ridge Crescent, 119260, Singapore, Singapore.
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26
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Nainu F, Mamada SS, Harapan H, Emran TB. Inflammation-Mediated Responses in the Development of Neurodegenerative Diseases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1411:39-70. [PMID: 36949305 DOI: 10.1007/978-981-19-7376-5_3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/24/2023]
Abstract
Since its first description over a century ago, neurodegenerative diseases (NDDs) have impaired the lives of millions of people worldwide. As one of the major threats to human health, NDDs are characterized by progressive loss of neuronal structure and function, leading to the impaired function of the CNS. While the precise mechanisms underlying the emergence of NDDs remains elusive, association of neuroinflammation with the emergence of NDDs has been suggested. The immune system is tightly controlled to maintain homeostatic milieu and failure in doing so has been shown catastrophic. Here, we review current concepts on the cellular and molecular drivers responsible in the induction of neuroinflammation and how such event further promotes neuronal damage leading to neurodegeneration. Experimental data generated from cell culture and animal studies, gross and molecular pathologies of human CNS samples, and genome-wide association study are discussed to provide deeper insights into the mechanistic details of neuroinflammation and its roles in the emergence of NDDs.
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Affiliation(s)
- Firzan Nainu
- Department of Pharmacy, Faculty of Pharmacy, Hasanuddin University, Makassar, Indonesia
| | - Sukamto S Mamada
- Department of Pharmacy, Faculty of Pharmacy, Hasanuddin University, Makassar, Indonesia
| | - Harapan Harapan
- School of Medicine, Universitas Syiah Kuala, Banda Aceh, Indonesia
| | - Talha Bin Emran
- Department of Pharmacy, BGC Trust University Bangladesh, Chittagong, Bangladesh
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27
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Different Intermolecular Interactions Drive Nonpathogenic Liquid-Liquid Phase Separation and Potentially Pathogenic Fibril Formation by TDP-43. Int J Mol Sci 2022; 23:ijms232315227. [PMID: 36499553 PMCID: PMC9741235 DOI: 10.3390/ijms232315227] [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: 09/26/2022] [Revised: 11/03/2022] [Accepted: 11/18/2022] [Indexed: 12/07/2022] Open
Abstract
The liquid-liquid phase separation (LLPS) of proteins has been found ubiquitously in eukaryotic cells, and is critical in the control of many biological processes by forming a temporary condensed phase with different bimolecular components. TDP-43 is recruited to stress granules in cells and is the main component of TDP-43 granules and proteinaceous amyloid inclusions in patients with amyotrophic lateral sclerosis (ALS). TDP-43 low complexity domain (LCD) is able to de-mix in solution, forming the protein condensed droplets, and amyloid aggregates would form from the droplets after incubation. The molecular interactions regulating TDP-43 LCD LLPS were investigated at the protein fusion equilibrium stage, when the droplets stopped growing after incubation. We found the molecules in the droplet were still liquid-like, but with enhanced intermolecular helix-helix interactions. The protein would only start to aggregate after a lag time and aggregate slower than at the condition when the protein does not phase separately into the droplets, or the molecules have a reduced intermolecular helix-helix interaction. In the protein condensed droplets, a structural transition intermediate toward protein aggregation was discovered involving a decrease in the intermolecular helix-helix interaction and a reduction in the helicity. Our results therefore indicate that different intermolecular interactions drive LLPS and fibril formation. The discovery that TDP-43 LCD aggregation was faster through the pathway without the first protein phase separation supports that LLPS and the intermolecular helical interaction could help maintain the stability of TDP-43 LCD.
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28
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Arg/Lys-containing IDRs are cryptic binding domains for ATP and nucleic acids that interplay to modulate LLPS. Commun Biol 2022; 5:1315. [PMID: 36450893 PMCID: PMC9712531 DOI: 10.1038/s42003-022-04293-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022] Open
Abstract
Most membrane-less organelles (MLOs) formed by LLPS contain both nucleic acids and IDR-rich proteins. Currently while IDRs are well-recognized to drive LLPS, nucleic acids are thought to exert non-specific electrostatic/salt effects. TDP-43 functions by binding RNA/ssDNA and its LLPS was characterized without nucleic acids to be driven mainly by PLD-oligomerization, which may further transit into aggregation characteristic of various neurodegenerative diseases. Here by NMR, we discovered unexpectedly for TDP-43 PLD: 1) ssDNAs drive and then dissolve LLPS by multivalently and specifically binding Arg/Lys. 2) LLPS is driven by nucleic-acid-binding coupled with PLD-oligomerization. 3) ATP and nucleic acids universally interplay in modulating LLPS by competing for binding Arg/Lys. However, the unique hydrophobic region within PLD renders LLPS to exaggerate into aggregation. The study not only unveils the first residue-resolution mechanism of the nucleic-acid-driven LLPS of TDP-43 PLD, but also decodes a general principle that not just TDP-43 PLD, all Arg/Lys-containing IDRs are cryptic nucleic-acid-binding domains that may phase separate upon binding nucleic acids. Strikingly, ATP shares a common mechanism with nucleic acids in binding IDRs, thus emerging as a universal mediator for interactions between IDRs and nucleic acids, which may underlie previously-unrecognized roles of ATP at mM in physiology and pathology.
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29
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Li F, Chen Y, Liu X, Tang Y, Dong X, Wei G. Atomistic Insights into A315E Mutation-Enhanced Pathogenicity of TDP-43 Core Fibrils. ACS Chem Neurosci 2022; 13:2743-2754. [PMID: 36053560 DOI: 10.1021/acschemneuro.2c00416] [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: 01/20/2023] Open
Abstract
The aggregation of TAR DNA-binding protein of 43 kDa (TDP-43) into fibrillary deposits is implicated in amyotrophic lateral sclerosis (ALS), and some hereditary mutations localized in the low complexity domain (LCD) facilitate the formation of pathogenic TDP-43 fibrils. A recent cryo-EM study reported the atomic-level structures of the A315E TDP-43 LCD (residues 288-319, TDP-43288-319) core fibril in which the protofilaments have R-shaped structures and hypothesized that A315E U-shaped protofilaments can readily convert to R-shaped protofilaments compared to the wild-type (WT) ones. There are no atomic structures of WT protofilaments available yet. Herein, we performed extensive all-atom explicit-solvent molecular dynamics simulations on A315E and WT protofilaments starting from both the cryo-EM-determined R-shaped and our constructed U-shaped structures. Our simulations show that WT protofilaments also adopt the R-shaped structures but are less stable than their A315E counterparts. Except for R293-E315 salt bridges, N312-F316 hydrophobic interactions and F316-F316 π-π stacking interactions are also crucial for the stabilization of the neck region of the R-shaped A315E protofilaments. The loss of R293-E315 salt bridges and the weakened interactions of N312-F316 and F316-F316 result in the reduced stability of the R-shaped WT protofilaments. Simulations starting from U-shaped folds reveal that A315E protofilaments can spontaneously convert to the cryo-EM-derived R-shaped protofilaments, whereas WT protofilaments convert to R-shape-like structures with remodeled neck regions. The R-shape-like WT protofilaments could act as intermediate states slowing down the U-to-R transition. This study reveals that A315E mutation can not only enhance the structural stability of the R-shaped TDP-43288-319 protofilaments but also promote the U-to-R transition, which provides atomistic insights into the A315E mutation-enhanced TDP-43 pathogenicity in ALS.
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Affiliation(s)
- Fangying Li
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Yujie Chen
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Xianshi Liu
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Yiming Tang
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, China
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30
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Chiang WC, Fang YS, Lye YS, Weng TY, Ganesan K, Huang SH, Chang LY, Chou SC, Chen YR. Hyperphosphorylation-Mimetic TDP-43 Drives Amyloid Formation and Possesses Neuronal Toxicity at the Oligomeric Stage. ACS Chem Neurosci 2022; 13:2599-2612. [PMID: 36007056 DOI: 10.1021/acschemneuro.1c00873] [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: 01/20/2023] Open
Abstract
TDP-43 proteinopathies cover a range of neurodegenerative diseases, including frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). Hyperphosphorylated TDP-43 was found within the inclusion bodies in disease lesions; however, the role of hyperphosphorylation and the toxic species are still ambiguous. To characterize the hyperphosphorylation effect of TDP-43, here, we employed five serine mutations implicated in the diseases at serine locations 379, 403, 404, 409, and 410 in the C-terminus to aspartate (S5D) and to alanine (S5A). We systematically characterized the conformation, liquid-liquid phase separation, oligomerization, and fibrillization of TDP-43 variants. Results revealed that the recombinant TDP-43 variants readily formed structurally similar spherical oligomers, as evidenced by circular dichroism spectroscopy, fluorescence spectroscopy, the TDP-43 oligomer-specific antibody assay, dynamic light scattering, and transmission electron microscopy. After incubation, only the phosphor-mimic S5D TDP-43 formed thioflavin-positive amyloid fibrils, whereas wild-type and S5A TDP-43 formed amorphous aggregates. We also examined membrane disruption, the cytotoxicity of human neuroblastoma, and the synaptic loss of primary neurons induced by oligomers and large aggregates of TDP-43. The results showed that all oligomeric TDP-43 variants were toxic regardless of hyperphosphorylation, but the fibrils and amorphous aggregates were not. Overall, our results demonstrated the hyperphosphorylation effect on fibril formation and the toxicity attributed from TDP-43 oligomers. This study facilitates the understanding and therapeutic development for TDP-43 proteinopathies.
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Affiliation(s)
- Wan-Chin Chiang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Yu-Sheng Fang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan.,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, 101, Kuang-Fu Rd., Sec. 2., Hsinchu 30013, Taiwan
| | - Yuh Shen Lye
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan.,Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Taipei 11529, Taiwan
| | - Tzu-Yu Weng
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Kiruthika Ganesan
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Shih-Han Huang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Lan-Yun Chang
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Shih-Chieh Chou
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan
| | - Yun-Ru Chen
- Genomics Research Center, Academia Sinica, 128, Academia Rd., Sec. 2, Nankang District, Taipei 11529, Taiwan.,Institute of Bioinformatics and Structural Biology, National Tsing Hua University, 101, Kuang-Fu Rd., Sec. 2., Hsinchu 30013, Taiwan.,Taiwan International Graduate Program in Interdisciplinary Neuroscience, National Cheng Kung University and Academia Sinica, Taipei 11529, Taiwan
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31
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Paron F, Barattucci S, Cappelli S, Romano M, Berlingieri C, Stuani C, Laurents D, Mompeán M, Buratti E. Unravelling the toxic effects mediated by the neurodegenerative disease-associated S375G mutation of TDP-43 and its S375E phosphomimetic variant. J Biol Chem 2022; 298:102252. [PMID: 35835219 PMCID: PMC9364110 DOI: 10.1016/j.jbc.2022.102252] [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: 01/15/2022] [Revised: 06/23/2022] [Accepted: 06/25/2022] [Indexed: 12/05/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is a nucleic acid–binding protein found in the nucleus that accumulates in the cytoplasm under pathological conditions, leading to proteinopathies, such as frontotemporal dementia and ALS. An emerging area of TDP-43 research is represented by the study of its post-translational modifications, the way they are connected to disease-associated mutations, and what this means for pathological processes. Recently, we described a novel mutation in TDP-43 in an early onset ALS case that was affecting a potential phosphorylation site in position 375 (S375G). A preliminary characterization showed that both the S375G mutation and its phosphomimetic variant, S375E, displayed altered nuclear–cytoplasmic distribution and cellular toxicity. To better investigate these effects, here we established cell lines expressing inducible WT, S375G, and S375E TDP-43 variants. Interestingly, we found that these mutants do not seem to affect well-studied aspects of TDP-43, such as RNA splicing or autoregulation, or protein conformation, dynamics, or aggregation, although they do display dysmorphic nuclear shape and cell cycle alterations. In addition, RNA-Seq analysis of these cell lines showed that although the disease-associated S375G mutation and its phosphomimetic S375E variant regulate distinct sets of genes, they have a common target in mitochondrial apoptotic genes. Taken together, our data strongly support the growing evidence that alterations in TDP-43 post-translational modifications can play a potentially important role in disease pathogenesis and provide a further link between TDP-43 pathology and mitochondrial health.
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Affiliation(s)
- Francesca Paron
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy
| | - Simone Barattucci
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy
| | - Sara Cappelli
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy
| | - Maurizio Romano
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | - Christian Berlingieri
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy
| | - Cristiana Stuani
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy
| | - Douglas Laurents
- "Rocasolano" Institute for Physical Chemistry, Spanish National Research Council, Serrano 119, 28006, Madrid, Spain
| | - Miguel Mompeán
- "Rocasolano" Institute for Physical Chemistry, Spanish National Research Council, Serrano 119, 28006, Madrid, Spain
| | - Emanuele Buratti
- Molecular Pathology, International Centre for Genetic and Engineering Biotechnology (ICGEB), Trieste, Italy.
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32
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Garg DK, Bhat R. Modulation of assembly of TDP-43 low-complexity domain by heparin: From droplets to amyloid fibrils. Biophys J 2022; 121:2568-2582. [PMID: 35644946 PMCID: PMC9300664 DOI: 10.1016/j.bpj.2022.05.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 09/03/2021] [Accepted: 05/25/2022] [Indexed: 11/02/2022] Open
Abstract
TAR DNA-binding protein 43 (TDP-43) is an RNA-regulating protein that carries out many cellular functions through liquid-liquid phase separation (LLPS). The LLPS of TDP-43 is mediated by its C-terminal low-complexity domain (TDP43-LCD) corresponding to the region 267-414. In neurodegenerative disorders amyotrophic lateral sclerosis and frontotemporal dementia, pathological inclusions of the TDP-43 are found that are rich in the C-terminal fragments of ∼25 and ∼35 kDa, of which TDP43-LCD is a part. Thus, understanding the assembly process of TDP43-LCD is essential, given its involvement in the formation of both functional liquid-like assemblies and solid- or gel-like pathological aggregates. Here, we show that the solution pH and salt modulate TDP43-LCD LLPS. A gradual reduction in the pH below its isoelectric point of 9.8 results in a monotonic decrease of TDP43-LCD LLPS due to charge-charge repulsion between monomers, while at pH 6 and below no LLPS was observed. The addition of heparin to TDP43-LCD solution at pH 6, at a 1:2 heparin-to-TDP43-LCD molar ratio, promotes TDP43-LCD LLPS, while at higher concentration, it disrupts LLPS through a reentrant phase transition. Upon incubation at pH 6, TDP43-LCD undergoes gelation without phase separation. However, in the reentrant regime in the presence of a high heparin concentration, it forms thick amyloid aggregates that are significantly more SDS resistant than the gel. The results indicate that the material nature of the TDP43-LCD assembly products can be modulated by heparin which is significant in the context of liquid-to-solid phase transition observed in TDP-43 proteinopathies. Our findings are also crucial in relation to similar transitions that could occur due to alteration in the molecular level interactions among various multivalent biomolecules involving other LCDs and RNAs.
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Affiliation(s)
| | - Rajiv Bhat
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India.
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33
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Zhou X, Sumrow L, Tashiro K, Sutherland L, Liu D, Qin T, Kato M, Liszczak G, McKnight SL. Mutations linked to neurological disease enhance self-association of low-complexity protein sequences. Science 2022; 377:eabn5582. [PMID: 35771920 PMCID: PMC9610444 DOI: 10.1126/science.abn5582] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Protein domains of low sequence complexity do not fold into stable, three-dimensional structures. Nevertheless, proteins with these sequences assist in many aspects of cell organization, including assembly of nuclear and cytoplasmic structures not surrounded by membranes. The dynamic nature of these cellular assemblies is caused by the ability of low-complexity domains (LCDs) to transiently self-associate through labile, cross-β structures. Mechanistic studies useful for the study of LCD self-association have evolved over the past decade in the form of simple assays of phase separation. Here, we have used such assays to demonstrate that the interactions responsible for LCD self-association can be dictated by labile protein structures poised close to equilibrium between the folded and unfolded states. Furthermore, missense mutations causing Charcot-Marie-Tooth disease, frontotemporal dementia, and Alzheimer's disease manifest their pathophysiology in vitro and in cultured cell systems by enhancing the stability of otherwise labile molecular structures formed upon LCD self-association.
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Liu X, Lao Z, Li X, Dong X, Wei G. ALS-associated A315E and A315pT variants exhibit distinct mechanisms in inducing irreversible aggregation of TDP-43 312-317 peptides. Phys Chem Chem Phys 2022; 24:16263-16273. [PMID: 35758309 DOI: 10.1039/d2cp01625g] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Amyotrophic lateral sclerosis (ALS) is intensively associated with insoluble aggregates formed by transactivation response element DNA-binding protein 43 (TDP-43) in the cytoplasm of neuron cells. A recent experimental study reported that two ALS-linked familial variants, A315E and A315pT (pT, phosphorylated threonine), can induce irreversible aggregation of the TDP-43 312NFGAFS317 segment (TDP-43312-317). However, the underlying molecular mechanism remains largely elusive. Here, we investigated the early aggregation process of the wild type (WT) 312NFGAFS317 segment and its A315E and A315pT variants by performing multiple microsecond all-atom molecular dynamics simulations. Our simulations show that the two variants display lower fluidity than WT, consistent with their decreased labilities observed in previous denaturation assay experiments. Despite each of the two variants carrying one negative charge, unexpectedly, we find that both A315E mutation and A315pT phosphorylation enhance intermolecular interactions and result in the formation of more compact oligomers. Compared to WT, A315E oligomers possess low β-sheet content but a compact hydrophobic core, while A315pT oligomers have high β-sheet content and large β-sheets. Side chain hydrogen-bonding and hydrophobic interactions as well as N312-E315 salt bridges contribute most to the increased aggregation propensity of the A315E mutant. By contrast, main chain and side chain hydrogen-bonding interactions, side chain hydrophobic and aromatic interactions, are crucial to the enhanced aggregation capability of the A315pT variant. These results indicate that glutamate mutation and phosphorylation at position 315 induce the irreversible aggregation of TDP-43312-317 peptides through differential mechanisms, which remind us that we should be careful in the investigation of the phosphorylation effect on protein aggregation by using phosphomimetic substitutions. This study provides mechanistic insights into the A315E/A315pT-induced irreversible aggregation of TDP-43312-317, which may be helpful for the in-depth understanding of ALS-mutation/phosphorylation-associated liquid-to-solid phase transition of TDP-43 protein aggregates.
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Affiliation(s)
- Xianshi Liu
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, P. R. China.
| | - Zenghui Lao
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, P. R. China.
| | - Xuhua Li
- MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi'an Jiaotong University, Xi'an 710049, P. R. China
| | - Xuewei Dong
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, P. R. China.
| | - Guanghong Wei
- Department of Physics, State Key Laboratory of Surface Physics, and Key Laboratory for Computational Physical Sciences (Ministry of Education), Fudan University, Shanghai 200438, P. R. China.
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Vishal SS, Wijegunawardana D, Salaikumaran MR, Gopal PP. Sequence Determinants of TDP-43 Ribonucleoprotein Condensate Formation and Axonal Transport in Neurons. Front Cell Dev Biol 2022; 10:876893. [PMID: 35646935 PMCID: PMC9133736 DOI: 10.3389/fcell.2022.876893] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/21/2022] [Indexed: 11/17/2022] Open
Abstract
Mutations in TDP-43, a RNA-binding protein with multiple functions in RNA metabolism, cause amyotrophic lateral sclerosis (ALS), but it is uncertain how defects in RNA biology trigger motor neuron degeneration. TDP-43 is a major constituent of ribonucleoprotein (RNP) granules, phase separated biomolecular condensates that regulate RNA splicing, mRNA transport, and translation. ALS-associated TDP-43 mutations, most of which are found in the low complexity domain, promote aberrant liquid to solid phase transitions and impair the dynamic liquid-like properties and motility of RNP transport granules in neurons. Here, we perform a comparative analysis of ALS-linked mutations and TDP-43 variants in order to identify critical structural elements, aromatic and charged residues that are key determinants of TDP-43 RNP transport and condensate formation in neurons. We find that A315T and Q343R disease-linked mutations and substitutions of aromatic residues within the α-helical domain and LARKS, show the most severe defects in TDP-43 RNP granule transport and impair both anterograde and retrograde motility. F313L and F313-6L/Y substitutions of one or both phenylalanine residues in LARKS suggest the aromatic rings are important for TDP-43 RNP transport. Similarly, W334F/L substitutions of the tryptophan residue in the α-helical domain, impair TDP-43 RNP motility (W334L) or anterograde transport (W334F). We also show that R293A and R293K mutations, which disrupt the only RGG in the LCD, profoundly reduce long-range, directed transport and net velocity of TDP-43 RNP granules. In the disordered regions flanking the α-helical domain, we find that F283Y, F397Y or Y374F substitutions of conserved GF/G and SYS motifs, also impair anterograde and/or retrograde motility, possibly by altering hydrophobicity. Similarly, ALS-linked mutations in disordered regions distant from the α-helical domain also show anterograde transport deficits, consistent with previous findings, but these mutations are less severe than A315T and Q343R. Overall our findings demonstrate that the conserved α-helical domain, phenylalanine residues within LARKS and RGG motif are key determinants of TDP-43 RNP transport, suggesting they may mediate efficient recruitment of motors and adaptor proteins. These results offer a possible mechanism underlying ALS-linked TDP-43 defects in axonal transport and homeostasis.
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Affiliation(s)
- Sonali S. Vishal
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
| | | | | | - Pallavi P. Gopal
- Department of Pathology, Yale School of Medicine, New Haven, CT, United States
- Program in Cellular Neuroscience, Neurodegeneration, and Repair, Yale School of Medicine, New Haven, CT, United States
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36
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Hu L, Mao S, Lin L, Bai G, Liu B, Mao J. Stress granules in the spinal muscular atrophy and amyotrophic lateral sclerosis: The correlation and promising therapy. Neurobiol Dis 2022; 170:105749. [PMID: 35568100 DOI: 10.1016/j.nbd.2022.105749] [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: 01/22/2022] [Revised: 03/27/2022] [Accepted: 05/05/2022] [Indexed: 10/18/2022] Open
Abstract
Increasing genetic and biochemical evidence has broadened our view of the pathomechanisms that lead to Spinal muscular atrophy (SMA) and Amyotrophic lateral sclerosis (ALS), two fatal neurodegenerative diseases with similar symptoms and causes. Stress granules are dynamic cytosolic storage hubs for mRNAs in response to stress exposures, that are evolutionarily conserved cytoplasmic RNA granules in somatic cells. A lot of previous studies have shown that the impaired stress granules are crucial events in SMA/ALS pathogenesis. In this review, we described the key stress granules related RNA binding proteins (SMN, TDP-43, and FUS) involved in SMA/ALS, summarized the reported mutations in these RNA binding proteins involved in SMA/ALS pathogenesis, and discussed the mechanisms through which stress granules dynamics participate in the diseases. Meanwhile, we described the applications and limitation of current therapies targeting SMA/ALS. We futher proposed the promising targets on stress granules in the future therapeutic interventions of SMA/ALS.
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Affiliation(s)
- LiDan Hu
- the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China.
| | - Shanshan Mao
- the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Li Lin
- the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Guannan Bai
- the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
| | - Bingjie Liu
- State Key Laboratory of Membrane Biology, School of Life Sciences, Tsinghua University, Beijing 100084, China
| | - Jianhua Mao
- the Children's Hospital, Zhejiang University School of Medicine, National Clinical Research Center for Child Health, Hangzhou 310052, China
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37
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Bhopatkar AA, Dhakal S, Abernathy HG, Morgan SE, Rangachari V. Charge and Redox States Modulate Granulin-TDP-43 Coacervation Toward Phase Separation or Aggregation. Biophys J 2022; 121:2107-2126. [PMID: 35490297 DOI: 10.1016/j.bpj.2022.04.034] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 04/05/2022] [Accepted: 04/27/2022] [Indexed: 11/26/2022] Open
Abstract
Cytoplasmic inclusions containing aberrant proteolytic fragments of TDP-43 are associated with frontotemporal lobar degeneration (FTLD) and other related pathologies. In FTLD, TDP-43 is translocated into the cytoplasm and proteolytically cleaved to generate a prion-like domain (PrLD) containing C-terminal fragments (C25 and C35) that form toxic inclusions. Under stress, TDP-43 partitions into membraneless organelles called stress granules (SGs) by coacervating with RNA and other proteins. To glean into the factors that influence the dynamics between these cytoplasmic foci, we investigated the effects of cysteine-rich granulins (GRNs 1-7), which are the proteolytic products of progranulin, a protein implicated in FTLD, on TDP-43. We show that extracellular GRNs, typically generated during inflammation, internalize and colocalize with PrLD as puncta in the cytoplasm of neuroblastoma cells but show less likelihood of their presence in SGs. In addition, we show GRNs and PrLD coacervate to undergo liquid-liquid phase separation (LLPS) or form gel- or solid-like aggregates. Using charge patterning and conserved cysteines among the wild-type GRNs as guides, along with specifically engineered mutants, we discover that the negative charges on GRNs drive LLPS while the positive charges and the redox state of cysteines modulate these phase transitions. Furthermore, RNA and GRNs compete and expel one another from PrLD condensates, providing a basis for GRN's absence in SGs. Together, the results help uncover potential modulatory mechanisms by which extracellular GRNs, formed during chronic inflammatory conditions, could internalize, and modulate cytoplasmic TDP-43 inclusions in proteinopathies.
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Affiliation(s)
- Anukool A Bhopatkar
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406
| | - Shailendra Dhakal
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406
| | - Hannah G Abernathy
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg MS 39406
| | - Sarah E Morgan
- School of Polymer Science and Engineering, University of Southern Mississippi, Hattiesburg MS 39406
| | - Vijay Rangachari
- Department of Chemistry and Biochemistry, School of Mathematics and Natural Sciences, University of Southern Mississippi, Hattiesburg MS 39406;; Center for Molecular and Cellular Biosciences, University of Southern Mississippi, Hattiesburg MS 39406;.
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38
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Liu X, Pimm ML, Haarer B, Brawner AT, Henty-Ridilla JL. Biochemical characterization of actin assembly mechanisms with ALS-associated profilin variants. Eur J Cell Biol 2022; 101:151212. [PMID: 35248815 PMCID: PMC10163920 DOI: 10.1016/j.ejcb.2022.151212] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 02/23/2022] [Accepted: 02/25/2022] [Indexed: 12/26/2022] Open
Abstract
Eight separate mutations in the actin-binding protein profilin-1 have been identified as a rare cause of amyotrophic lateral sclerosis (ALS). Profilin is essential for many neuronal cell processes through its regulation of lipids, nuclear signals, and cytoskeletal dynamics, including actin filament assembly. Direct interactions between profilin and actin monomers inhibit actin filament polymerization. In contrast, profilin can also stimulate polymerization by simultaneously binding actin monomers and proline-rich tracts found in other proteins. Whether the ALS-associated mutations in profilin compromise these actin assembly functions is unclear. We performed a quantitative biochemical comparison of the direct and formin mediated impact for the eight ALS-associated profilin variants on actin assembly using classic protein-binding and single-filament microscopy assays. We determined that the binding constant of each profilin for actin monomers generally correlates with the actin nucleation strength associated with each ALS-related profilin. In the presence of formin, the A20T, R136W, Q139L, and C71G variants failed to activate the elongation phase of actin assembly. This diverse range of formin-activities is not fully explained through profilin-poly-L-proline (PLP) interactions, as all ALS-associated variants bind a formin-derived PLP peptide with similar affinities. However, chemical denaturation experiments suggest that the folding stability of these profilins impact some of these effects on actin assembly. Thus, changes in profilin protein stability and alterations in actin filament polymerization may both contribute to the profilin-mediated actin disruptions in ALS.
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Affiliation(s)
- Xinbei Liu
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Morgan L Pimm
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Brian Haarer
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Andrew T Brawner
- Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Jessica L Henty-Ridilla
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA; Department of Neuroscience & Physiology, SUNY Upstate Medical University, Syracuse, NY 13210, USA.
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39
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Salem A, Wilson CJ, Rutledge BS, Dilliott A, Farhan S, Choy WY, Duennwald ML. Matrin3: Disorder and ALS Pathogenesis. Front Mol Biosci 2022; 8:794646. [PMID: 35083279 PMCID: PMC8784776 DOI: 10.3389/fmolb.2021.794646] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 11/30/2021] [Indexed: 12/11/2022] Open
Abstract
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of both upper and lower motor neurons in the brain and spinal cord. ALS is associated with protein misfolding and inclusion formation involving RNA-binding proteins, including TAR DNA-binding protein (TDP-43) and fused in sarcoma (FUS). The 125-kDa Matrin3 is a highly conserved nuclear DNA/RNA-binding protein that is implicated in many cellular processes, including binding and stabilizing mRNA, regulating mRNA nuclear export, modulating alternative splicing, and managing chromosomal distribution. Mutations in MATR3, the gene encoding Matrin3, have been identified as causal in familial ALS (fALS). Matrin3 lacks a prion-like domain that characterizes many other ALS-associated RNA-binding proteins, including TDP-43 and FUS, however, our bioinformatics analyses and preliminary studies document that Matrin3 contains long intrinsically disordered regions that may facilitate promiscuous interactions with many proteins and may contribute to its misfolding. In addition, these disordered regions in Matrin3 undergo numerous post-translational modifications, including phosphorylation, ubiquitination and acetylation that modulate the function and misfolding of the protein. Here we discuss the disordered nature of Matrin3 and review the factors that may promote its misfolding and aggregation, two elements that might explain its role in ALS pathogenesis.
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Affiliation(s)
- Ahmed Salem
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Carter J. Wilson
- Department of Applied Mathematics, Western University, London, ON, Canada
| | - Benjamin S. Rutledge
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Allison Dilliott
- Department of Neurology and Neurosurgery, McGill Universty, Montreal, QC, Canada
| | - Sali Farhan
- Department of Neurology and Neurosurgery, McGill Universty, Montreal, QC, Canada
- Department of Human Genetics, McGill Universty, Montreal, QC, Canada
| | - Wing-Yiu Choy
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
| | - Martin L. Duennwald
- Department of Pathology and Laboratory Medicine, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada
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40
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Tejedor AR, Garaizar A, Ramírez J, Espinosa JR. 'RNA modulation of transport properties and stability in phase-separated condensates. Biophys J 2021; 120:5169-5186. [PMID: 34762868 DOI: 10.1101/2021.03.05.434111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/03/2021] [Indexed: 05/25/2023] Open
Abstract
One of the key mechanisms employed by cells to control their spatiotemporal organization is the formation and dissolution of phase-separated condensates. The balance between condensate assembly and disassembly can be critically regulated by the presence of RNA. In this work, we use a chemically-accurate sequence-dependent coarse-grained model for proteins and RNA to unravel the impact of RNA in modulating the transport properties and stability of biomolecular condensates. We explore the phase behavior of several RNA-binding proteins such as FUS, hnRNPA1, and TDP-43 proteins along with that of their corresponding prion-like domains and RNA recognition motifs from absence to moderately high RNA concentration. By characterizing the phase diagram, key molecular interactions, surface tension, and transport properties of the condensates, we report a dual RNA-induced behavior: on the one hand, RNA enhances phase separation at low concentration as long as the RNA radius of gyration is comparable to that of the proteins, whereas at high concentration, it inhibits the ability of proteins to self-assemble independently of its length. On the other hand, along with the stability modulation, the viscosity of the condensates can be considerably reduced at high RNA concentration as long as the length of the RNA chains is shorter than that of the proteins. Conversely, long RNA strands increase viscosity even at high concentration, but barely modify protein self-diffusion which mainly depends on RNA concentration and on the effect RNA has on droplet density. On the whole, our work rationalizes the different routes by which RNA can regulate phase separation and condensate dynamics, as well as the subsequent aberrant rigidification implicated in the emergence of various neuropathologies and age-related diseases.
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Affiliation(s)
- Andrés R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | - Adiran Garaizar
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge Ramírez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain.
| | - Jorge R Espinosa
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom.
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41
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Tejedor AR, Garaizar A, Ramírez J, Espinosa JR. 'RNA modulation of transport properties and stability in phase-separated condensates. Biophys J 2021; 120:5169-5186. [PMID: 34762868 PMCID: PMC8715277 DOI: 10.1016/j.bpj.2021.11.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 09/03/2021] [Accepted: 10/03/2021] [Indexed: 12/29/2022] Open
Abstract
One of the key mechanisms employed by cells to control their spatiotemporal organization is the formation and dissolution of phase-separated condensates. The balance between condensate assembly and disassembly can be critically regulated by the presence of RNA. In this work, we use a chemically-accurate sequence-dependent coarse-grained model for proteins and RNA to unravel the impact of RNA in modulating the transport properties and stability of biomolecular condensates. We explore the phase behavior of several RNA-binding proteins such as FUS, hnRNPA1, and TDP-43 proteins along with that of their corresponding prion-like domains and RNA recognition motifs from absence to moderately high RNA concentration. By characterizing the phase diagram, key molecular interactions, surface tension, and transport properties of the condensates, we report a dual RNA-induced behavior: on the one hand, RNA enhances phase separation at low concentration as long as the RNA radius of gyration is comparable to that of the proteins, whereas at high concentration, it inhibits the ability of proteins to self-assemble independently of its length. On the other hand, along with the stability modulation, the viscosity of the condensates can be considerably reduced at high RNA concentration as long as the length of the RNA chains is shorter than that of the proteins. Conversely, long RNA strands increase viscosity even at high concentration, but barely modify protein self-diffusion which mainly depends on RNA concentration and on the effect RNA has on droplet density. On the whole, our work rationalizes the different routes by which RNA can regulate phase separation and condensate dynamics, as well as the subsequent aberrant rigidification implicated in the emergence of various neuropathologies and age-related diseases.
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Affiliation(s)
- Andrés R Tejedor
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain
| | - Adiran Garaizar
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom
| | - Jorge Ramírez
- Department of Chemical Engineering, Universidad Politécnica de Madrid, Madrid, Spain.
| | - Jorge R Espinosa
- Cavendish Laboratory, Maxwell Centre, Department of Physics, University of Cambridge, Cambridge, United Kingdom.
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42
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Laurents DV, Stuani C, Pantoja-Uceda D, Buratti E, Mompeán M. Aromatic and aliphatic residues of the disordered region of TDP-43 are on a fast track for self-assembly. Biochem Biophys Res Commun 2021; 578:110-114. [PMID: 34560580 DOI: 10.1016/j.bbrc.2021.09.040] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 09/17/2021] [Indexed: 10/20/2022]
Abstract
The C-terminal, intrinsically disordered, prion-like domain (PrLD) of TDP-43 promotes liquid condensate and solid amyloid formation. These phase changes are crucial to the normal biological functions of the protein but also for its abnormal aggregation, which is implicated in amyotrophic lateral sclerosis (ALS) and certain dementias. We and other previously found that certain amyloid forms emerge from an intermediate condensed state that acts as a nucleus for fibrillization. To quantitatively ascertain the role of individual residues within TDP-43's PrLD in its early self-assembly we have followed the kinetics of NMR 1H-15N HSQC signal loss to obtain values for the lag time, elongation rate and extent of condensate formation at equilibrium. The results of this analysis represent a robust corroboration that aliphatic and aromatic residues are key drivers of condensate formation.
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Affiliation(s)
- Douglas V Laurents
- "Rocasolano" Institute for Physical Chemistry, Spanish National Research Council, Serrano 119, 28006, Madrid, Spain
| | - Cristiana Stuani
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, I-34149, Trieste, Italy
| | - David Pantoja-Uceda
- "Rocasolano" Institute for Physical Chemistry, Spanish National Research Council, Serrano 119, 28006, Madrid, Spain
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, I-34149, Trieste, Italy
| | - Miguel Mompeán
- "Rocasolano" Institute for Physical Chemistry, Spanish National Research Council, Serrano 119, 28006, Madrid, Spain.
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43
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Baudin A, Moreno-Romero AK, Xu X, Selig EE, Penalva LOF, Libich DS. Structural Characterization of the RNA-Binding Protein SERBP1 Reveals Intrinsic Disorder and Atypical RNA Binding Modes. Front Mol Biosci 2021; 8:744707. [PMID: 34631798 PMCID: PMC8497785 DOI: 10.3389/fmolb.2021.744707] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 09/07/2021] [Indexed: 11/18/2022] Open
Abstract
RNA binding proteins (RBPs) are essential for critical biological processes such as translation regulation and mRNA processing, and misfunctions of these proteins are associated with diseases such as cancer and neurodegeneration. SERBP1 (SERPINE1 mRNA Binding Protein 1) is an RBP that comprises two RG/RGG repeat regions yet lacks other recognizable RNA-binding motifs. It is involved in mRNA maturation, and translational regulation. It was initially identified as a hyaluronic acid binding protein, but recent studies have identified central roles for SERBP1 in brain function and development, especially neurogenesis and synaptogenesis. SERBP1 regulates One-carbon metabolism and epigenetic modification of histones, and increased SERBP1 expression in cancers such as leukemia, ovarian, prostate, liver and glioblastoma is correlated with poor patient outcomes. Despite these important regulatory roles for SERBP1, little is known about its structural and dynamic properties, nor about the molecular mechanisms governing its interaction with mRNA. Here, we define SERBP1 as an intrinsically disordered protein, containing highly conserved elements that were shown to be functionally important. The RNA binding activity of SERBP1 was explored using solution NMR and other biophysical techniques. The outcome of these experiments revealed that SERBP1 preferentially samples compact conformations including a central, stable α-helix and show that SERBP1 recognizes G-rich RNA sequences at the C-terminus involving the RGG box and neighboring residues. Despite the role in RNA recognition, the RGG boxes do not seem to stabilize the central helix and the central helix does not participate in RNA binding. Further, SERBP1 undergoes liquid-liquid phase separation, mediated by salt and RNA, and both RGG boxes are necessary for the efficient formation of condensed phases. Together, these results provide a foundation for understanding the molecular mechanisms of SERBP1 functions in physiological and pathological processes.
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Affiliation(s)
- Antoine Baudin
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Alma K Moreno-Romero
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Xiaoping Xu
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Emily E Selig
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - Luiz O F Penalva
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Cell Systems and Anatomy, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
| | - David S Libich
- Greehey Children's Cancer Research Institute, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States.,Department of Biochemistry and Structural Biology, The University of Texas Health Science Center at San Antonio, San Antonio, TX, United States
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44
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Gao J, Wang L, Ren X, Dunn JR, Peters A, Miyagi M, Fujioka H, Zhao F, Askwith C, Liang J, Wang X. Translational regulation in the brain by TDP-43 phase separation. J Cell Biol 2021; 220:e202101019. [PMID: 34427634 PMCID: PMC8404466 DOI: 10.1083/jcb.202101019] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 06/03/2021] [Accepted: 07/22/2021] [Indexed: 01/08/2023] Open
Abstract
The in vivo physiological function of liquid-liquid phase separation (LLPS) that governs non-membrane-bound structures remains elusive. Among LLPS-prone proteins, TAR DNA-binding protein of 43 kD (TDP-43) is under intense investigation because of its close association with neurological disorders. Here, we generated mice expressing endogenous LLPS-deficient murine TDP-43. LLPS-deficient TDP-43 mice demonstrate impaired neuronal function and behavioral abnormalities specifically related to brain function. Brain neurons of these mice, however, did not show TDP-43 proteinopathy or neurodegeneration. Instead, the global rate of protein synthesis was found to be greatly enhanced by TDP-43 LLPS loss. Mechanistically, TDP-43 LLPS ablation increased its association with PABPC4, RPS6, RPL7, and other translational factors. The physical interactions between TDP-43 and translational factors relies on a motif, the deletion of which abolished the impact of LLPS-deficient TDP-43 on translation. Our findings show a specific physiological role for TDP-43 LLPS in the regulation of brain function and uncover an intriguing novel molecular mechanism of translational control by LLPS.
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Affiliation(s)
- Ju Gao
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
| | - Luwen Wang
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
| | - Xiaojia Ren
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
| | - Justin R. Dunn
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
| | - Ariele Peters
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
| | - Masaru Miyagi
- Department of Pharmacology, Case Western Reserve University, Cleveland, OH
| | - Hisashi Fujioka
- Electron Microscopy Core Facility, Case Western Reserve University, Cleveland, OH
| | - Fangli Zhao
- Department of Neuroscience, The Ohio State University, Columbus, OH
| | - Candice Askwith
- Department of Neuroscience, The Ohio State University, Columbus, OH
| | - Jingjing Liang
- Department of Pathology, Case Western Reserve University, Cleveland, OH
| | - Xinglong Wang
- Department of Pharmacology and Experimental Neurosciences, University of Nebraska Medical Center, Omaha, NE
- Department of Pathology, Case Western Reserve University, Cleveland, OH
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45
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Houben B, Rousseau F, Schymkowitz J. Protein structure and aggregation: a marriage of necessity ruled by aggregation gatekeepers. Trends Biochem Sci 2021; 47:194-205. [PMID: 34561149 DOI: 10.1016/j.tibs.2021.08.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 08/25/2021] [Accepted: 08/31/2021] [Indexed: 12/27/2022]
Abstract
Protein aggregation propensity is a pervasive and seemingly inescapable property of proteomes. Strikingly, a significant fraction of the proteome is supersaturated, meaning that, for these proteins, their native conformation is less stable than the aggregated state. Maintaining the integrity of a proteome under such conditions is precarious and requires energy-consuming proteostatic regulation. Why then is aggregation propensity maintained at such high levels over long evolutionary timescales? Here, we argue that the conformational stability of the native and aggregated states are correlated thermodynamically and that codon usage strengthens this correlation. As a result, the folding of stable proteins requires kinetic control to avoid aggregation, provided by aggregation gatekeepers. These unique residues are evolutionarily selected to kinetically favor native folding, either on their own or by coopting chaperones.
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Affiliation(s)
- Bert Houben
- VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Frederic Rousseau
- VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
| | - Joost Schymkowitz
- VIB-KU Leuven Center for Brain and Disease Research, Leuven, Belgium; Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium.
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Loh D, Reiter RJ. Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders. Antioxidants (Basel) 2021; 10:1483. [PMID: 34573116 PMCID: PMC8465482 DOI: 10.3390/antiox10091483] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Revised: 09/10/2021] [Accepted: 09/13/2021] [Indexed: 12/12/2022] Open
Abstract
Biomolecular condensates are membraneless organelles (MLOs) that form dynamic, chemically distinct subcellular compartments organizing macromolecules such as proteins, RNA, and DNA in unicellular prokaryotic bacteria and complex eukaryotic cells. Separated from surrounding environments, MLOs in the nucleoplasm, cytoplasm, and mitochondria assemble by liquid-liquid phase separation (LLPS) into transient, non-static, liquid-like droplets that regulate essential molecular functions. LLPS is primarily controlled by post-translational modifications (PTMs) that fine-tune the balance between attractive and repulsive charge states and/or binding motifs of proteins. Aberrant phase separation due to dysregulated membrane lipid rafts and/or PTMs, as well as the absence of adequate hydrotropic small molecules such as ATP, or the presence of specific RNA proteins can cause pathological protein aggregation in neurodegenerative disorders. Melatonin may exert a dominant influence over phase separation in biomolecular condensates by optimizing membrane and MLO interdependent reactions through stabilizing lipid raft domains, reducing line tension, and maintaining negative membrane curvature and fluidity. As a potent antioxidant, melatonin protects cardiolipin and other membrane lipids from peroxidation cascades, supporting protein trafficking, signaling, ion channel activities, and ATPase functionality during condensate coacervation or dissolution. Melatonin may even control condensate LLPS through PTM and balance mRNA- and RNA-binding protein composition by regulating N6-methyladenosine (m6A) modifications. There is currently a lack of pharmaceuticals targeting neurodegenerative disorders via the regulation of phase separation. The potential of melatonin in the modulation of biomolecular condensate in the attenuation of aberrant condensate aggregation in neurodegenerative disorders is discussed in this review.
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Affiliation(s)
- Doris Loh
- Independent Researcher, Marble Falls, TX 78654, USA
| | - Russel J. Reiter
- Department of Cellular and Structural Biology, UT Health Science Center, San Antonio, TX 78229, USA
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Corbet GA, Wheeler JR, Parker R, Weskamp K. TDP43 ribonucleoprotein granules: physiologic function to pathologic aggregates. RNA Biol 2021; 18:128-138. [PMID: 34412568 DOI: 10.1080/15476286.2021.1963099] [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: 10/20/2022] Open
Abstract
Ribonucleoprotein (RNP) assemblies are ubiquitous in eukaryotic cells and have functions throughout RNA transcription, splicing, and stability. Of the RNA-binding proteins that form RNPs, TAR DNA-binding protein of 43 kD (TDP43) is of particular interest due to its essential nature and its association with disease. TDP43 plays critical roles in RNA metabolism, many of which require its recruitment to RNP granules such as stress granules, myo-granules, and neuronal transport granules. Moreover, the presence of cytoplasmic TDP43-positive inclusions is a pathological hallmark of several neurodegenerative diseases. Despite the pervasiveness of TDP43 aggregates, TDP43 mutations are exceedingly rare, suggesting that aggregation may be linked to dysregulation of TDP43 function. Oligomerization is a part of normal TDP43 function; thus, it is of interest to understand what triggers the irreversible aggregation that is seen in disease. Herein, we examine TDP43 functions, particularly in RNP granules, and the mechanisms which may explain pathological TDP43 aggregation.
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Affiliation(s)
- Giulia Ada Corbet
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA
| | | | - Roy Parker
- Department of Biochemistry, University of Colorado Boulder, Boulder, CO, USA.,Department of Chemistry, Howard Hughes Medical Institute, Chevy Chase, MD, USA
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Strategies in the design and development of (TAR) DNA-binding protein 43 (TDP-43) binding ligands. Eur J Med Chem 2021; 225:113753. [PMID: 34388383 DOI: 10.1016/j.ejmech.2021.113753] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 07/16/2021] [Accepted: 08/05/2021] [Indexed: 01/09/2023]
Abstract
The human transactive responsive (TAR) DNA-binding protein 43 (TDP-43) is involved in a number of physiological processes in the body. Its primary function involves RNA regulation. The TDP-43 protein is also involved in many diseases such as amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), Alzheimer's disease (AD), Parkinson's disease (PD) and even cancers. These TDP-43 mediated diseases are collectively called as TDP-43 proteinopathies. Intense research in the last decade has increased our understanding on TDP-43 structure and function in biology. The three-dimensional structures of TDP-43 domains such as N-terminal domain (NTD), RNA-recognition motif-1 (RRM1), RNA-recognition motif-2 (RRM2) and the C-terminal domain (CTD) or low-complexity domain (LCD) have been solved. These structures have yielded insights into novel binding sites and pockets at various TDP-43 domains, which can be targeted by designing a diverse library of ligands including small molecules, peptides and oligonucleotides as molecular tools to (i) study TDP-43 function, (ii) develop novel diagnostic agents and (iii) discover disease-modifying therapies to treat TDP-43 proteinopathies. This review provides a summary on recent progress in the development of TDP-43 binding ligands and uses the solved structures of various TDP-43 domains to investigate putative ligand binding regions that can be exploited to discover novel molecular probes to modulate TDP-43 structure and function.
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Structural biology of RNA-binding proteins in the context of phase separation: What NMR and EPR can bring? Curr Opin Struct Biol 2021; 70:132-138. [PMID: 34371262 DOI: 10.1016/j.sbi.2021.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 07/01/2021] [Indexed: 11/24/2022]
Abstract
Liquid-liquid phase separation of RNA-binding proteins underlies the formation of membraneless organelles, whose composition is dynamic and whose existence may be transient. These organelles are involved in regulation of RNA processing and translation and, if they behave abnormally, in pathologies. Because disorder phenomena are essential in their formation and dynamics, established methodology is insufficient for characterizing their structure. In this review, we consider the current and potential contribution of NMR and EPR spectroscopy to the understanding of structure and dynamics of phase-separating RNA-binding proteins in, both, their dispersed and condensed state in vitro. We discuss which experiments are applicable under what conditions and which information can be obtained from them. Because for these phenomena, the accessible information depends crucially on metastable phase equilibria, we also consider aspects of sample preparation for NMR and EPR experiments.
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50
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Francois-Moutal L, Scott DD, Khanna M. Direct targeting of TDP-43, from small molecules to biologics: the therapeutic landscape. RSC Chem Biol 2021; 2:1158-1166. [PMID: 34458829 PMCID: PMC8341936 DOI: 10.1039/d1cb00110h] [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: 05/17/2021] [Accepted: 06/18/2021] [Indexed: 11/21/2022] Open
Abstract
Tar DNA binding (TDP)-43 proteinopathy, typically described as cytoplasmic accumulation of highly modified and misfolded TDP-43 molecules, is characteristic of several neurodegenerative diseases such as Amyotrophic Lateral Sclerosis (ALS) and limbic-predominant age-related TDP-43 encephalopathy (LATE). TDP-43 proposed proteinopathies include homeostatic imbalance between nuclear and cytoplasmic localization, aggregation of ubiquitinated and hyper-phosphorylated TDP-43, and an increase in protein truncation of cytoplasmic TDP-43. Given the therapeutic interest of targeting TDP-43, this review focuses on the current landscape of strategies, ranging from biologics to small molecules, that directly target TDP-43. Antibodies, peptides and compounds have been designed or found to recognize specific TDP-43 sequences but alleviate TDP-43 toxicity through different mechanisms. While two antibodies described here were able to induce degradation of pathological TDP-43, the peptides and small molecules were primarily designed to reduce aggregation of TDP-43. Furthermore, we discuss promising emerging therapeutic targets.
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Affiliation(s)
- Liberty Francois-Moutal
- Department of Pharmacology, College of Medicine, University of Arizona 1501 North Campbell Drive, P.O. Box 245050 Tucson AZ 85724 USA +520-626-2204 +520-626-2147
- Center of Innovation in Brain Science Tucson AZ 85721 USA
| | - David Donald Scott
- Department of Pharmacology, College of Medicine, University of Arizona 1501 North Campbell Drive, P.O. Box 245050 Tucson AZ 85724 USA +520-626-2204 +520-626-2147
- Center of Innovation in Brain Science Tucson AZ 85721 USA
| | - May Khanna
- Department of Pharmacology, College of Medicine, University of Arizona 1501 North Campbell Drive, P.O. Box 245050 Tucson AZ 85724 USA +520-626-2204 +520-626-2147
- Center of Innovation in Brain Science Tucson AZ 85721 USA
- Bio5 Institute, University of Arizona Tucson USA
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