1
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Koizumi T, Fujimoto A, Kawaguchi H, Kurosaki T, Kitamura A. Stress Granule Dysfunction via Chromophore-Associated Light Inactivation. ACS OMEGA 2024; 9:21298-21306. [PMID: 38764671 PMCID: PMC11097178 DOI: 10.1021/acsomega.4c01469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 04/17/2024] [Accepted: 04/23/2024] [Indexed: 05/21/2024]
Abstract
Stress granules (SGs) are cytoplasmic condensates composed of various proteins and RNAs that protect translation-associated machinery from harmful conditions during stress. However, the method of spatiotemporal inactivation of condensates such as SGs in live cells to study cellular phenotypes is still in the process of being demonstrated. Here, we show that the inactivation of SGs by chromophore-associated light inactivation (CALI) using a genetically encoded red fluorescence protein (SuperNova-Red) as a photosensitizer leads to differences in cell viability during recovery from hyperosmotic stress. CALI delayed the disassembly kinetics of SGs during recovery from hyperosmotic stress. Consequently, CALI could inactivate the SGs, and the cellular fate due to SGs could be analyzed. Furthermore, CALI is an effective spatiotemporal knockdown method for intracellular condensates/aggregates and would contribute to the elucidation of importance of such condensates/aggregates.
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Affiliation(s)
- Takumi Koizumi
- Laboratory
of Cellular and Molecular Sciences, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Ai Fujimoto
- Laboratory
of Cellular and Molecular Sciences, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Haruka Kawaguchi
- Laboratory
of Cellular and Molecular Sciences, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Tsumugi Kurosaki
- Laboratory
of Cellular and Molecular Sciences, Graduate School of Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Akira Kitamura
- Laboratory
of Cellular and Molecular Sciences, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
- PRIME, Japan
Agency for Medical Research and Development, Chiyoda-ku, Tokyo 100-004, Japan
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2
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Augspach A, Drake KD, Roma L, Qian E, Lee SR, Clarke D, Kumar S, Jaquet M, Gallon J, Bolis M, Triscott J, Galván JA, Chen Y, Thalmann GN, Kruithof-de Julio M, Theurillat JPP, Wuchty S, Gerstein M, Piscuoglio S, Kanadia RN, Rubin MA. Minor intron splicing is critical for survival of lethal prostate cancer. Mol Cell 2023; 83:1983-2002.e11. [PMID: 37295433 PMCID: PMC10637423 DOI: 10.1016/j.molcel.2023.05.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2022] [Revised: 03/29/2023] [Accepted: 05/12/2023] [Indexed: 06/12/2023]
Abstract
The evolutionarily conserved minor spliceosome (MiS) is required for protein expression of ∼714 minor intron-containing genes (MIGs) crucial for cell-cycle regulation, DNA repair, and MAP-kinase signaling. We explored the role of MIGs and MiS in cancer, taking prostate cancer (PCa) as an exemplar. Both androgen receptor signaling and elevated levels of U6atac, a MiS small nuclear RNA, regulate MiS activity, which is highest in advanced metastatic PCa. siU6atac-mediated MiS inhibition in PCa in vitro model systems resulted in aberrant minor intron splicing leading to cell-cycle G1 arrest. Small interfering RNA knocking down U6atac was ∼50% more efficient in lowering tumor burden in models of advanced therapy-resistant PCa compared with standard antiandrogen therapy. In lethal PCa, siU6atac disrupted the splicing of a crucial lineage dependency factor, the RE1-silencing factor (REST). Taken together, we have nominated MiS as a vulnerability for lethal PCa and potentially other cancers.
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Affiliation(s)
- Anke Augspach
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
| | - Kyle D Drake
- Physiology and Neurobiology Department, University of Connecticut, Storrs, CT 06269, USA
| | - Luca Roma
- Institute of Pathology and Medical Genetics, University Hospital Basel, 4056 Basel, Switzerland
| | - Ellen Qian
- Department of Computer Science, Yale University, New Haven, CT 06520, USA; Yale College, New Haven, CT 06520, USA
| | - Se Ri Lee
- Department of Computer Science, Yale University, New Haven, CT 06520, USA; Yale College, New Haven, CT 06520, USA
| | - Declan Clarke
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Sushant Kumar
- Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Muriel Jaquet
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
| | - John Gallon
- Institute of Pathology and Medical Genetics, University Hospital Basel, 4056 Basel, Switzerland
| | - Marco Bolis
- Institute of Oncology Research, 6500 Bellinzona, Switzerland; Computational Oncology Unit, Department of Oncology, Istituto di Ricerche Farmacologiche "Mario Negri" IRCCS, 20156 Milano, Italy
| | - Joanna Triscott
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland
| | - José A Galván
- Institute of Pathology, University of Bern, Bern 3008, Switzerland
| | - Yu Chen
- Human Oncology and Pathogenesis Program (HOPP), Memorial Sloan Kettering, New York, NY 10065, USA; Department of Medicine, Memorial Sloan Kettering, New York, NY 10065, USA; Department of Medicine, Weill Cornell Medicine, New York, NY 10065, USA
| | - George N Thalmann
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland; Department of Urology, Inselspital, Bern University Hospital, 3008 Bern, Switzerland
| | - Marianna Kruithof-de Julio
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland; Department of Urology, Inselspital, Bern University Hospital, 3008 Bern, Switzerland; Bern Center for Precision Medicine, University of Bern and Inselspital, 3008 Bern, Switzerland
| | - Jean-Philippe P Theurillat
- Institute of Oncology Research, 6500 Bellinzona, Switzerland; Faculty of Biomedical Sciences, Università della Svizzera italiana, 6900 Lugano, Switzerland
| | - Stefan Wuchty
- Department of Computer Science, University of Miami, Coral Gables, FL 33146, USA; Sylvester Comprehensive Cancer Center, University of Miami, Coral Gables, FL 33136, USA; Department of Biology, University of Miami, Coral Gables, FL 33146, USA
| | - Mark Gerstein
- Department of Computer Science, Yale University, New Haven, CT 06520, USA; Program in Computational Biology and Bioinformatics, Yale University, New Haven, CT 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Salvatore Piscuoglio
- Institute of Pathology and Medical Genetics, University Hospital Basel, 4056 Basel, Switzerland; Department of Biomedicine, University of Basel, 4031 Basel, Switzerland
| | - Rahul N Kanadia
- Physiology and Neurobiology Department, University of Connecticut, Storrs, CT 06269, USA; Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA.
| | - Mark A Rubin
- Department for BioMedical Research, University of Bern, 3008 Bern, Switzerland; Bern Center for Precision Medicine, University of Bern and Inselspital, 3008 Bern, Switzerland.
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3
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Wolin E, Guo JK, Blanco MR, Perez AA, Goronzy IN, Abdou AA, Gorhe D, Guttman M, Jovanovic M. SPIDR: a highly multiplexed method for mapping RNA-protein interactions uncovers a potential mechanism for selective translational suppression upon cellular stress. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.05.543769. [PMID: 37333139 PMCID: PMC10274648 DOI: 10.1101/2023.06.05.543769] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
RNA binding proteins (RBPs) play crucial roles in regulating every stage of the mRNA life cycle and mediating non-coding RNA functions. Despite their importance, the specific roles of most RBPs remain unexplored because we do not know what specific RNAs most RBPs bind. Current methods, such as crosslinking and immunoprecipitation followed by sequencing (CLIP-seq), have expanded our knowledge of RBP-RNA interactions but are generally limited by their ability to map only one RBP at a time. To address this limitation, we developed SPIDR (Split and Pool Identification of RBP targets), a massively multiplexed method to simultaneously profile global RNA binding sites of dozens to hundreds of RBPs in a single experiment. SPIDR employs split-pool barcoding coupled with antibody-bead barcoding to increase the throughput of current CLIP methods by two orders of magnitude. SPIDR reliably identifies precise, single-nucleotide RNA binding sites for diverse classes of RBPs simultaneously. Using SPIDR, we explored changes in RBP binding upon mTOR inhibition and identified that 4EBP1 acts as a dynamic RBP that selectively binds to 5'-untranslated regions of specific translationally repressed mRNAs only upon mTOR inhibition. This observation provides a potential mechanism to explain the specificity of translational regulation controlled by mTOR signaling. SPIDR has the potential to revolutionize our understanding of RNA biology and both transcriptional and post-transcriptional gene regulation by enabling rapid, de novo discovery of RNA-protein interactions at an unprecedented scale.
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Affiliation(s)
- Erica Wolin
- Department of Biological Sciences, Columbia University, New York City, New York 10027, USA
| | - Jimmy K. Guo
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena CA 91125, USA
- Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Mario R. Blanco
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena CA 91125, USA
| | - Andrew A. Perez
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena CA 91125, USA
| | - Isabel N. Goronzy
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena CA 91125, USA
| | - Ahmed A. Abdou
- Department of Biological Sciences, Columbia University, New York City, New York 10027, USA
| | - Darvesh Gorhe
- Department of Biological Sciences, Columbia University, New York City, New York 10027, USA
| | - Mitchell Guttman
- Division of Biology and Bioengineering, California Institute of Technology, Pasadena CA 91125, USA
| | - Marko Jovanovic
- Department of Biological Sciences, Columbia University, New York City, New York 10027, USA
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4
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Dash BP, Freischmidt A, Weishaupt JH, Hermann A. Downstream Effects of Mutations in SOD1 and TARDBP Converge on Gene Expression Impairment in Patient-Derived Motor Neurons. Int J Mol Sci 2022; 23:ijms23179652. [PMID: 36077049 PMCID: PMC9456253 DOI: 10.3390/ijms23179652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/19/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Amyotrophic Lateral Sclerosis (ALS) is a progressive and fatal neurodegenerative disease marked by death of motor neurons (MNs) present in the spinal cord, brain stem and motor cortex. Despite extensive research, the reason for neurodegeneration is still not understood. To generate novel hypotheses of putative underlying molecular mechanisms, we used human induced pluripotent stem cell (hiPSCs)-derived motor neurons (MNs) from SOD1- and TARDBP (TDP-43 protein)-mutant-ALS patients and healthy controls to perform high-throughput RNA-sequencing (RNA-Seq). An integrated bioinformatics approach was employed to identify differentially expressed genes (DEGs) and key pathways underlying these familial forms of the disease (fALS). In TDP43-ALS, we found dysregulation of transcripts encoding components of the transcriptional machinery and transcripts involved in splicing regulation were particularly affected. In contrast, less is known about the role of SOD1 in RNA metabolism in motor neurons. Here, we found that many transcripts relevant for mitochondrial function were specifically altered in SOD1-ALS, indicating that transcriptional signatures and expression patterns can vary significantly depending on the causal gene that is mutated. Surprisingly, however, we identified a clear downregulation of genes involved in protein translation in SOD1-ALS suggesting that ALS-causing SOD1 mutations shift cellular RNA abundance profiles to cause neural dysfunction. Altogether, we provided here an extensive profiling of mRNA expression in two ALS models at the cellular level, corroborating the major role of RNA metabolism and gene expression as a common pathomechanism in ALS.
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Affiliation(s)
- Banaja P. Dash
- Translational Neurodegeneration Section “Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany
| | | | - Jochen H. Weishaupt
- Division of Neurodegeneration, Department of Neurology, Mannheim Center for Translational Neurosciences, Medical Faculty Mannheim, Heidelberg University, 68167 Mannheim, Germany
| | - Andreas Hermann
- Translational Neurodegeneration Section “Albrecht-Kossel”, Department of Neurology, University Medical Center Rostock, 18147 Rostock, Germany
- Center for Transdisciplinary Neurosciences Rostock, University Medical Center Rostock, 18147 Rostock, Germany
- Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE) Rostock/Greifswald, 18147 Rostock, Germany
- Correspondence: ; Tel.: +49-(0)381-494-9541; Fax: +49-(0)381-494-9542
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5
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Basak A, Basak S. Protein Aggregation and Self Assembly in Health and Disease. CURR PROTEOMICS 2022. [DOI: 10.2174/1570164618666210223160742] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
:
Self-attachment of proteins leading to the formation of highly insoluble protein oligomers and aggregates has become an important focus of research owing to its diverse implications in pathophysiology and diseases. This has become a more frequent phenomenon in most neurological and neurodegenerative diseases as well as in dementia. In recent years such event of protein aggregation has linked to other disease conditions, disorders or adverse health conditions. Interestingly, aggregation of protein also plays role in development, growth or metabolism. Most often physiological proteins are initially bio-synthesised in native or nascent geometrical forms or conformations but later they undergo specific folding pattern and thereby acquire a stable configuration that is biologically relevant and active. It is highly important that these proteins remain in their biologically active configuration in order to exert their functional properties. Any alteration or change to this structural configuration can be detrimental to their specific functions and may cause pathological consequences leading to the onset of diseases or disorders. Several factors such as the action of chaperones, binding partners, physiological metal ions, pH level, temperature, ionic strength, interfacial exposure (solid-liquid, liquid-liquid, gas-liquid), mutation and post translational modification, chemical changes, interaction with small molecules such as lipids, hormones, etc. and solvent environment have been either identified or proposed as important factors in conferring the ultimate status of protein structure and configuration.
Among many misfolding protein conformations, self-assembly or aggregation is the most significant. It leads to the formation of highly oligomeric self-aggregates that precipitate and interfere with many biochemical processes with serious pathological consequences. The most common implication of protein aggregation leading to the formation of deposits / plaques of various morphological types is the onset of neurological and neurodegenerative diseases that include Alzheimer’s, Parkinson’s, Huntington, ALS (Amyotrophic Lateral Sclerosis), CJD (Creutzfeldt Jakob Dementia), Prion diseases, Amyloidosis and other forms of dementia. However increasingly studies revealed that protein aggregation may also be associated with other diseases such as cancer, type 2 diabetes, renal, corneal and cardiovascular diseases. Protein aggregation diseases are now considered as part of “Proteinopathy” which refers to conditions where proteins become structurally abnormal or fail to fold into stable normal configurations. In this review, we reflect on various aspects of protein self-aggregation, potential underlying causes, mechanism, role of secondary structures, pathological consequences and possible intervention strategies as reported in published literatures.
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Affiliation(s)
- Ajoy Basak
- Pathology and Laboratory Medicine, Faculty of Medicine, U Ottawa, Canada
- Ottawa Hospital Research Institute,
The Ottawa Hospital, U Ottawa, Canada
| | - Sarmistha Basak
- Formerly of Kidney Research Center, Ottawa Hospital Research Institute, U Ottawa, Canada
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6
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USP15 Deubiquitinates TUT1 Associated with RNA Metabolism and Maintains Cerebellar Homeostasis. Mol Cell Biol 2020; 40:MCB.00098-20. [PMID: 32839293 DOI: 10.1128/mcb.00098-20] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 08/13/2020] [Indexed: 12/30/2022] Open
Abstract
Precise regulation of RNA metabolism is crucial for dynamic gene expression and controlling cellular functions. In the nervous system, defects in RNA metabolism are implicated in the disturbance of brain homeostasis and development. Here, we report that deubiquitinating enzyme, ubiquitin specific peptidase 15 (USP15), deubiquitinates terminal uridylyl transferase 1 (TUT1) and changes global RNA metabolism. We found that the expression of USP15 redistributes TUT1 from the nucleolus to nucleoplasm, resulting in the stabilization of U6 snRNA. We also found that lack of the Usp15 gene induces an impairment in motor ability with an unconventional cerebellar formation. Moreover, inhibition of the USP15-TUT1 cascade triggered mild and chronic endoplasmic reticulum (ER) stress. Therefore, our results suggest that USP15 is crucial for mRNA metabolism and maintains a healthy brain. These findings provide a possibility that disturbance of the USP15-TUT1 cascade induces chronic and mild ER stress, leading to an acceleration of the neurodegenerative phenotype.
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7
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Splicing Players Are Differently Expressed in Sporadic Amyotrophic Lateral Sclerosis Molecular Clusters and Brain Regions. Cells 2020; 9:cells9010159. [PMID: 31936368 PMCID: PMC7017305 DOI: 10.3390/cells9010159] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 12/23/2019] [Accepted: 01/04/2020] [Indexed: 12/12/2022] Open
Abstract
Splicing is a tightly orchestrated process by which the brain produces protein diversity over time and space. While this process specializes and diversifies neurons, its deregulation may be responsible for their selective degeneration. In amyotrophic lateral sclerosis (ALS), splicing defects have been investigated at the singular gene level without considering the higher-order level, involving the entire splicing machinery. In this study, we analyzed the complete spectrum (396) of genes encoding splicing factors in the motor cortex (41) and spinal cord (40) samples from control and sporadic ALS (SALS) patients. A substantial number of genes (184) displayed significant expression changes in tissue types or disease states, were implicated in distinct splicing complexes and showed different topological hierarchical roles based on protein–protein interactions. The deregulation of one of these splicing factors has a central topological role, i.e., the transcription factor YBX1, which might also have an impact on stress granule formation, a pathological marker associated with ALS.
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8
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Perrone B, La Cognata V, Sprovieri T, Ungaro C, Conforti FL, Andò S, Cavallaro S. Alternative Splicing of ALS Genes: Misregulation and Potential Therapies. Cell Mol Neurobiol 2019; 40:1-14. [PMID: 31385134 DOI: 10.1007/s10571-019-00717-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/31/2019] [Indexed: 12/12/2022]
Abstract
Neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), Parkinson's, Alzheimer's, and Huntington's disease affect a rapidly increasing population worldwide. Although common pathogenic mechanisms have been identified (e.g., protein aggregation or dysfunction, immune response alteration and axonal degeneration), the molecular events underlying timing, dosage, expression, and location of RNA molecules are still not fully elucidated. In particular, the alternative splicing (AS) mechanism is a crucial player in RNA processing and represents a fundamental determinant for brain development, as well as for the physiological functions of neuronal circuits. Although in recent years our knowledge of AS events has increased substantially, deciphering the molecular interconnections between splicing and ALS remains a complex task and still requires considerable efforts. In the present review, we will summarize the current scientific evidence outlining the involvement of AS in the pathogenic processes of ALS. We will also focus on recent insights concerning the tuning of splicing mechanisms by epigenomic and epi-transcriptomic regulation, providing an overview of the available genomic technologies to investigate AS drivers on a genome-wide scale, even at a single-cell level resolution. In the future, gene therapy strategies and RNA-based technologies may be utilized to intercept or modulate the splicing mechanism and produce beneficial effects against ALS.
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Affiliation(s)
- Benedetta Perrone
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Valentina La Cognata
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy
| | - Teresa Sprovieri
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Carmine Ungaro
- Institute for Biomedical Research and Innovation, National Research Council, Mangone, Cosenza, Italy
| | - Francesca Luisa Conforti
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Andò
- Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Arcavacata di Rende, Cosenza, Italy.,Centro Sanitario, University of Calabria, Arcavacata di Rende, Cosenza, Italy
| | - Sebastiano Cavallaro
- Institute for Biomedical Research and Innovation, National Research Council, Catania, Italy.
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9
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Kitamura A, Iwasaki N, Kinjo M. Molecular chaperone HSP70 prevents formation of inclusion bodies of the 25-kDa C-terminal fragment of TDP-43 by preventing aggregate accumulation. Cell Stress Chaperones 2018; 23:1177-1183. [PMID: 30099725 PMCID: PMC6237682 DOI: 10.1007/s12192-018-0930-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/08/2018] [Accepted: 05/25/2018] [Indexed: 01/12/2023] Open
Abstract
Transactive response DNA/RNA-binding protein 43-kDa (TDP-43) C-terminal fragments, such as a 25-kDa fragment (TDP-25), have been identified as a ubiquitinated and phosphorylated components of inclusion bodies (IBs) in motor neurons from amyotrophic lateral sclerosis patients. Cells contain proteins that function as molecular chaperones and prevent aggregate formation of misfolded and aggregation-prone proteins. Recently, we reported that heat shock protein (HSP)70, an abundant molecular chaperone, binds to TDP-25 in an ATP-dependent manner; however, whether HSP70 can prevent the formation of TDP-25-related IBs remains unknown. Here, we showed that HSP70 prevented TDP-25 aggregation according to green fluorescent protein-tagged TDP-25 (G-TDP-25) colocalization in the cytoplasm with mCherry-tagged HSP70 (HSP70-R). The mobile fraction of HSP70-R in the cytoplasmic IBs associated with G-TDP-25 increased relative to that of G-TDP-25, suggesting that HSP70 strongly bound to G-TDP-25 in the IBs, whereas a portion remained dissociated from the IBs. Importantly, the proportion of G-TDP-25 IBs was significantly decreased by HSP70-R overexpression; however, G-TDP-25 levels in the insoluble fraction remained unchanged by HSP70-R overexpression, suggesting that G-TDP-25 formed aggregated species that cannot be dissolved, even in the presence of strong detergents. These results indicated that HSP70 prevented the accumulation of G-TDP-25 aggregates in cytoplasmic IBs, but was insufficient for G-TDP-25 disassembly and solubilization.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, 001-0021, Japan
| | - Nodoka Iwasaki
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, 001-0021, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, 001-0021, Japan.
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10
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Abstract
Trans activation response DNA/RNA-binding protein 43 kDa (TDP-43) regulates RNA splicing and stability. TDP-43 is a component of ubiquitin-positive inclusion bodies of motor neurons from patients with amyotrophic lateral sclerosis, suggesting a role in disease pathogenesis. Toxic intracellular TDP-43 aggregation may cause neuronal cell death. The loss of TDP-43 in animal models causes lethality in early development. Furthermore, TDP-43 knockdown in adult animals and cells increases aberrant splicing. Uridine-rich small nuclear RNA (U snRNA) regulation is disrupted in cultured neuroblastoma cells with TDP-43 knockdown and in motor neurons in amyotrophic lateral sclerosis. Aberrant mRNA splicing and U snRNA expression are likely key processes in neuronal cell death. We review the research history and future perspectives of aberrant splicing by TDP-43 loss.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan 001-0021
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11
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Kitamura A, Shibasaki A, Takeda K, Suno R, Kinjo M. Analysis of the substrate recognition state of TDP-43 to single-stranded DNA using fluorescence correlation spectroscopy. Biochem Biophys Rep 2018; 14:58-63. [PMID: 29872735 PMCID: PMC5986658 DOI: 10.1016/j.bbrep.2018.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 03/28/2018] [Accepted: 03/30/2018] [Indexed: 11/15/2022] Open
Abstract
Normal function and abnormal aggregation of transactivation response (TAR) DNA/RNA-binding protein 43 kDa (TDP-43) are directly associated with the lethal genetic diseases: cystic fibrosis, amyotrophic lateral sclerosis (ALS), and frontotemporal lobar degeneration (FTLD). The binding of TDP-43 to single-stranded DNA (ssDNA) or RNA is involved in transcriptional repression, regulation of RNA splicing, and RNA stabilization. Equilibrium dissociation constants (Kd) of TDP-43 and ssDNA or RNA have been determined using various methods; however, methods that can measure Kd with high sensitivity in a short time using a small amount of TDP-43 in solution would be advantageous. Here, in order to determine the Kd of TDP-43 and fluorescence-labeled ssDNA as well as the binding stoichiometry, we use fluorescence correlation spectroscopy (FCS), which detects the slowed diffusion of molecular interactions in solution with single-molecule sensitivity, in addition to electrophoretic mobility shift assay (EMSA). Using tandem affinity chromatography of TDP-43 dually tagged with glutathione-S-transferase and poly-histidine tags, highly purified protein was obtained. FCS successfully detected specific interaction between purified TDP-43 and TG ssDNA repeats, with a Kd in the nanomolar range. The Kd of the TDP-43 mutant was not different from the wild type, although mutant oligomers, which did not bind ssDNA, were observed. Analysis of the fluorescence brightness per dimerized TDP-43/ssDNA complex was used to evaluate their binding stoichiometry. The results suggest that an assay combining FCS and EMSA can precisely analyze ssDNA recognition mechanisms, and that FCS may be applied for the rapid and quantitative determination of the interaction strength between TDP-43 and ssDNA or RNA. These methods will aid in the elucidation of the substrate recognition mechanism of ALS- and FTLD-associated variants of TDP-43. The dissociation constant (Kd) of TDP-43 and single stranded DNA was determined. Wild type and amyotrophic lateral sclerosis mutant TDP-43 had similar Kd values. Stoichiometric analysis suggests that TDP-43 dimers bind to two molecules of ssDNA.
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Affiliation(s)
- Akira Kitamura
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Ai Shibasaki
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Kayo Takeda
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
| | - Ryoji Suno
- Department of Cell Biology, Graduate School of Medicine, Kyoto University, Kyoto 605-8501, Japan
| | - Masataka Kinjo
- Laboratory of Molecular Cell Dynamics, Faculty of Advanced Life Science, Hokkaido University, Sapporo 001-0021, Japan
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