1
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Martínez-Cenalmor P, Martínez AE, Moneo-Corcuera D, González-Jiménez P, Pérez-Sala D. Oxidative stress elicits the remodeling of vimentin filaments into biomolecular condensates. Redox Biol 2024; 75:103282. [PMID: 39079387 PMCID: PMC11338992 DOI: 10.1016/j.redox.2024.103282] [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: 07/02/2024] [Revised: 07/21/2024] [Accepted: 07/21/2024] [Indexed: 08/23/2024] Open
Abstract
The intermediate filament protein vimentin performs an essential role in cytoskeletal interplay and dynamics, mechanosensing and cellular stress responses. In pathology, vimentin is a key player in tumorigenesis, fibrosis and infection. Vimentin filaments undergo distinct and versatile reorganizations, and behave as redox sensors. The vimentin monomer possesses a central α-helical rod domain flanked by N- and C-terminal low complexity domains. Interactions between this type of domains play an important function in the formation of phase-separated biomolecular condensates, which in turn are critical for the organization of cellular components. Here we show that several oxidants, including hydrogen peroxide and diamide, elicit the remodeling of vimentin filaments into small particles. Oxidative stress elicited by diamide induces a fast dissociation of filaments into circular, motile dots, which requires the presence of the single vimentin cysteine residue, C328. This effect is reversible, and filament reassembly can occur within minutes of oxidant removal. Diamide-elicited vimentin droplets recover fluorescence after photobleaching. Moreover, fusion of cells expressing differentially tagged vimentin allows the detection of dots positive for both tags, indicating that vimentin dots merge upon cell fusion. The aliphatic alcohol 1,6-hexanediol, known to alter interactions between low complexity domains, readily dissolves diamide-elicited vimentin dots at low concentrations, in a C328 dependent manner, and hampers reassembly. Taken together, these results indicate that vimentin oxidation promotes a fast and reversible filament remodeling into biomolecular condensate-like structures, and provide primary evidence of its regulated phase separation. Moreover, we hypothesize that filament to droplet transition could play a protective role against irreversible damage of the vimentin network by oxidative stress.
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Affiliation(s)
- Paula Martínez-Cenalmor
- Department of Cellular and Molecular Biosciences, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain
| | - Alma E Martínez
- Department of Cellular and Molecular Biosciences, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain
| | - Diego Moneo-Corcuera
- Department of Cellular and Molecular Biosciences, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain
| | - Patricia González-Jiménez
- Department of Cellular and Molecular Biosciences, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain
| | - Dolores Pérez-Sala
- Department of Cellular and Molecular Biosciences, Centro de Investigaciones Biológicas Margarita Salas, CSIC, 28040, Madrid, Spain.
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2
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Yu Z, Wang Q, Zhang Q, Tian Y, Yan G, Zhu J, Zhu G, Zhang Y. Decoding the genomic landscape of chromatin-associated biomolecular condensates. Nat Commun 2024; 15:6952. [PMID: 39138204 PMCID: PMC11322608 DOI: 10.1038/s41467-024-51426-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 08/05/2024] [Indexed: 08/15/2024] Open
Abstract
Biomolecular condensates play a significant role in chromatin activities, primarily by concentrating and compartmentalizing proteins and/or nucleic acids. However, their genomic landscapes and compositions remain largely unexplored due to a lack of dedicated computational tools for systematic identification in vivo. To address this, we develop CondSigDetector, a computational framework designed to detect condensate-like chromatin-associated protein co-occupancy signatures (CondSigs), to predict genomic loci and component proteins of distinct chromatin-associated biomolecular condensates. Applying this framework to mouse embryonic stem cells (mESC) and human K562 cells enable us to depict the high-resolution genomic landscape of chromatin-associated biomolecular condensates, and uncover both known and potentially unknown biomolecular condensates. Multi-omics analysis and experimental validation further verify the condensation properties of CondSigs. Additionally, our investigation sheds light on the impact of chromatin-associated biomolecular condensates on chromatin activities. Collectively, CondSigDetector provides an approach to decode the genomic landscape of chromatin-associated condensates, facilitating a deeper understanding of their biological functions and underlying mechanisms in cells.
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Affiliation(s)
- Zhaowei Yu
- State Key Laboratory of Cardiovascular Diseases and Medical Innovation Center, Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Qi Wang
- State Key Laboratory of Cardiovascular Diseases and Medical Innovation Center, Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China
| | - Qichen Zhang
- Pancreatic Intensive Care Unit, Changhai hospital, Naval Medical University, Shanghai, 200433, China
- Lingang Laboratory, Shanghai, 200031, China
| | - Yawen Tian
- Lingang Laboratory, Shanghai, 200031, China
| | - Guo Yan
- Lingang Laboratory, Shanghai, 200031, China
| | - Jidong Zhu
- Etern Biopharma, Shanghai, 201203, China
| | - Guangya Zhu
- Lingang Laboratory, Shanghai, 200031, China.
| | - Yong Zhang
- State Key Laboratory of Cardiovascular Diseases and Medical Innovation Center, Institute for Regenerative Medicine, Department of Neurosurgery, Shanghai East Hospital, Shanghai Key Laboratory of Signaling and Disease Research, Frontier Science Center for Stem Cell Research, School of Life Sciences and Technology, Tongji University, Shanghai, 200092, China.
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3
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Scott-Hewitt N, Mahoney M, Huang Y, Korte N, Yvanka de Soysa T, Wilton DK, Knorr E, Mastro K, Chang A, Zhang A, Melville D, Schenone M, Hartigan C, Stevens B. Microglial-derived C1q integrates into neuronal ribonucleoprotein complexes and impacts protein homeostasis in the aging brain. Cell 2024; 187:4193-4212.e24. [PMID: 38942014 DOI: 10.1016/j.cell.2024.05.058] [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: 05/31/2023] [Revised: 01/08/2024] [Accepted: 05/31/2024] [Indexed: 06/30/2024]
Abstract
Neuroimmune interactions mediate intercellular communication and underlie critical brain functions. Microglia, CNS-resident macrophages, modulate the brain through direct physical interactions and the secretion of molecules. One such secreted factor, the complement protein C1q, contributes to complement-mediated synapse elimination in both developmental and disease models, yet brain C1q protein levels increase significantly throughout aging. Here, we report that C1q interacts with neuronal ribonucleoprotein (RNP) complexes in an age-dependent manner. Purified C1q protein undergoes RNA-dependent liquid-liquid phase separation (LLPS) in vitro, and the interaction of C1q with neuronal RNP complexes in vivo is dependent on RNA and endocytosis. Mice lacking C1q have age-specific alterations in neuronal protein synthesis in vivo and impaired fear memory extinction. Together, our findings reveal a biophysical property of C1q that underlies RNA- and age-dependent neuronal interactions and demonstrate a role of C1q in critical intracellular neuronal processes.
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Affiliation(s)
- Nicole Scott-Hewitt
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
| | - Matthew Mahoney
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Youtong Huang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Nils Korte
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - T Yvanka de Soysa
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Daniel K Wilton
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Emily Knorr
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Kevin Mastro
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Allison Chang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Allison Zhang
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - David Melville
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA
| | - Monica Schenone
- The Broad Proteomics Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Christina Hartigan
- The Broad Proteomics Platform, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Beth Stevens
- F.M. Kirby Neurobiology Center, Boston Children's Hospital, Boston, MA 02115, USA; The Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Howard Hughes Medical Investigator, Boston Children's Hospital, Boston, MA 02115, USA.
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4
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Glon D, Léonardon B, Guillemot A, Albertini A, Lagaudrière-Gesbert C, Gaudin Y. Biomolecular condensates with liquid properties formed during viral infections. Microbes Infect 2024:105402. [PMID: 39127089 DOI: 10.1016/j.micinf.2024.105402] [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: 02/02/2024] [Revised: 07/10/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024]
Abstract
During a viral infection, several membraneless compartments with liquid properties are formed. They can be of viral origin concentrating viral proteins and nucleic acids, and harboring essential stages of the viral cycle, or of cellular origin containing components involved in innate immunity. This is a paradigm shift in our understanding of viral replication and the interaction between viruses and innate cellular immunity.
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Affiliation(s)
- Damien Glon
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Benjamin Léonardon
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Ariane Guillemot
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Aurélie Albertini
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Cécile Lagaudrière-Gesbert
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
| | - Yves Gaudin
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
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5
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Li Q, Hariri S, Calidas A, Kaur A, Huey E, Engebrecht J. The chromatin-associated 53BP1 ortholog, HSR-9, regulates recombinational repair and X chromosome segregation in the Caenorhabditis elegans germ line. Genetics 2024; 227:iyae102. [PMID: 38884610 DOI: 10.1093/genetics/iyae102] [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: 04/16/2024] [Revised: 05/29/2024] [Accepted: 06/03/2024] [Indexed: 06/18/2024] Open
Abstract
53BP1 plays a crucial role in regulating DNA damage repair pathway choice and checkpoint signaling in somatic cells; however, its role in meiosis has remained enigmatic. In this study, we demonstrate that the Caenorhabditis elegans ortholog of 53BP1, HSR-9, associates with chromatin in both proliferating and meiotic germ cells. Notably, HSR-9 is enriched on the X chromosome pair in pachytene oogenic germ cells. HSR-9 is also present at kinetochores during both mitotic and meiotic divisions but does not appear to be essential for monitoring microtubule-kinetochore attachments or tension. Using cytological markers of different steps in recombinational repair, we found that HSR-9 influences the processing of a subset of meiotic double-stranded breaks into COSA-1-marked crossovers. Additionally, HSR-9 plays a role in meiotic X chromosome segregation under conditions where X chromosomes fail to pair, synapse, and recombine. Together, these results highlight that chromatin-associated HSR-9 has both conserved and unique functions in the regulation of meiotic chromosome behavior.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, CA 95616, USA
| | - Sara Hariri
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, CA 95616, USA
| | - Aashna Calidas
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
| | - Arshdeep Kaur
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
| | - Erica Huey
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, University of California Davis, Davis, CA 95616, USA
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, CA 95616, USA
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6
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Munshi R. How Transcription Factor Clusters Shape the Transcriptional Landscape. Biomolecules 2024; 14:875. [PMID: 39062589 PMCID: PMC11274464 DOI: 10.3390/biom14070875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2024] [Revised: 07/14/2024] [Accepted: 07/16/2024] [Indexed: 07/28/2024] Open
Abstract
In eukaryotic cells, gene transcription typically occurs in discrete periods of promoter activity, interspersed with intervals of inactivity. This pattern deviates from simple stochastic events and warrants a closer examination of the molecular interactions that activate the promoter. Recent studies have identified transcription factor (TF) clusters as key precursors to transcriptional bursting. Often, these TF clusters form at chromatin segments that are physically distant from the promoter, making changes in chromatin conformation crucial for promoter-TF cluster interactions. In this review, I explore the formation and constituents of TF clusters, examining how the dynamic interplay between chromatin architecture and TF clustering influences transcriptional bursting. Additionally, I discuss techniques for visualizing TF clusters and provide an outlook on understanding the remaining gaps in this field.
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Affiliation(s)
- Rahul Munshi
- Joseph Henry Laboratories of Physics and Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
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7
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Son JB, Kim S, Yang S, Ahn Y, Lee NK. Analysis of Fluorescent Proteins for Observing Single Gene Locus in a Live and Fixed Escherichia coli Cell. J Phys Chem B 2024; 128:6730-6741. [PMID: 38968413 PMCID: PMC11264270 DOI: 10.1021/acs.jpcb.4c01816] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 06/21/2024] [Accepted: 06/27/2024] [Indexed: 07/07/2024]
Abstract
Fluorescent proteins (FPs) are essential tools for advanced microscopy techniques such as super-resolution imaging, single-particle tracking, and quantitative single-molecule counting. Various FPs fused to DNA-binding proteins have been used to observe the subcellular location and movement of specific gene loci in living and fixed bacterial cells. However, quantitative assessments of the properties of FPs for gene locus measurements are still lacking. Here, we assessed various FPs to observe specific gene loci in live and fixed Escherichia coli cells using a fluorescent repressor-operator binding system (FROS), tet operator-Tet repressor proteins (TetR). Tsr-fused FPs were used to assess the intensity and photostability of various FPs (five red FPs: mCherry2, FusionRed, mRFP, mCrimson3, and dKatushka; and seven yellow FPs: SYFP2, Venus, mCitrine, YPet, mClover3, mTopaz, and EYFP) at the single-molecule level in living cells. These FPs were then used for gene locus measurements using FROS. Our results indicate that TetR-mCrimson3 (red) and TetR-EYFP (yellow) had better properties for visualizing gene loci than the other TetR-FPs. Furthermore, fixation procedures affected the clustering of diffusing TetR-FPs and altered the locations of the TetR-FP foci. Fixation with formaldehyde consistently disrupted proper DNA locus observations using TetR-FPs. Notably, the foci measured using TetR-mCrimson3 remained close to their original positions in live cells after glyoxal fixation. This in vivo study provides a cell-imaging guide for the use of FPs for gene-locus observation in E. coli and a scheme for evaluating the use of FPs for other cell-imaging purposes.
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Affiliation(s)
| | | | | | - Youmin Ahn
- Department of Chemistry, Seoul
National University, 08826 Seoul, South
Korea
| | - Nam Ki Lee
- Department of Chemistry, Seoul
National University, 08826 Seoul, South
Korea
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8
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Yang JH, Hansen AS. Enhancer selectivity in space and time: from enhancer-promoter interactions to promoter activation. Nat Rev Mol Cell Biol 2024; 25:574-591. [PMID: 38413840 DOI: 10.1038/s41580-024-00710-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/30/2024] [Indexed: 02/29/2024]
Abstract
The primary regulators of metazoan gene expression are enhancers, originally functionally defined as DNA sequences that can activate transcription at promoters in an orientation-independent and distance-independent manner. Despite being crucial for gene regulation in animals, what mechanisms underlie enhancer selectivity for promoters, and more fundamentally, how enhancers interact with promoters and activate transcription, remain poorly understood. In this Review, we first discuss current models of enhancer-promoter interactions in space and time and how enhancers affect transcription activation. Next, we discuss different mechanisms that mediate enhancer selectivity, including repression, biochemical compatibility and regulation of 3D genome structure. Through 3D polymer simulations, we illustrate how the ability of 3D genome folding mechanisms to mediate enhancer selectivity strongly varies for different enhancer-promoter interaction mechanisms. Finally, we discuss how recent technical advances may provide new insights into mechanisms of enhancer-promoter interactions and how technical biases in methods such as Hi-C and Micro-C and imaging techniques may affect their interpretation.
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Affiliation(s)
- Jin H Yang
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA
| | - Anders S Hansen
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Gene Regulation Observatory, Broad Institute of MIT and Harvard, Cambridge, MA, USA.
- Koch Institute for Integrative Cancer Research, Cambridge, MA, USA.
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9
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Presman DM, Benítez B, Lafuente AL, Vázquez Lareu A. Chromatin structure and dynamics: one nucleosome at a time. Histochem Cell Biol 2024; 162:79-90. [PMID: 38607419 DOI: 10.1007/s00418-024-02281-1] [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] [Accepted: 03/19/2024] [Indexed: 04/13/2024]
Abstract
Eukaryotic genomes store information on many levels, including their linear DNA sequence, the posttranslational modifications of its constituents (epigenetic modifications), and its three-dimensional folding. Understanding how this information is stored and read requires multidisciplinary collaborations from many branches of science beyond biology, including physics, chemistry, and computer science. Concurrent recent developments in all these areas have enabled researchers to image the genome with unprecedented spatial and temporal resolution. In this review, we focus on what single-molecule imaging and tracking of individual proteins in live cells have taught us about chromatin structure and dynamics. Starting with the basics of single-molecule tracking (SMT), we describe some advantages over in situ imaging techniques and its current limitations. Next, we focus on single-nucleosome studies and what they have added to our current understanding of the relationship between chromatin dynamics and transcription. In celebration of Robert Feulgen's ground-breaking discovery that allowed us to start seeing the genome, we discuss current models of chromatin structure and future challenges ahead.
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Affiliation(s)
- Diego M Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
| | - Belén Benítez
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Agustina L Lafuente
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Alejo Vázquez Lareu
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
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10
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Barkley RJR, Crowley JC, Brodrick AJ, Zipfel WR, Parker JSL. Fluorescent protein tags affect the condensation properties of a phase-separating viral protein. Mol Biol Cell 2024; 35:ar100. [PMID: 38809580 PMCID: PMC11244164 DOI: 10.1091/mbc.e24-01-0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 05/30/2024] Open
Abstract
Fluorescent protein (FP) tags are extensively used to visualize and characterize the properties of biomolecular condensates despite a lack of investigation into the effects of these tags on phase separation. Here, we characterized the dynamic properties of µNS, a viral protein hypothesized to undergo phase separation and the main component of mammalian orthoreovirus viral factories. Our interest in the sequence determinants and nucleation process of µNS phase separation led us to compare the size and density of condensates formed by FP::µNS to the untagged protein. We found an FP-dependent increase in droplet size and density, which suggests that FP tags can promote µNS condensation. To further assess the effect of FP tags on µNS droplet formation, we fused FP tags to µNS mutants to show that the tags could variably induce phase separation of otherwise noncondensing proteins. By comparing fluorescent constructs with untagged µNS, we identified mNeonGreen as the least artifactual FP tag that minimally perturbed µNS condensation. These results show that FP tags can promote phase separation and that some tags are more suitable for visualizing and characterizing biomolecular condensates with minimal experimental artifacts.
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Affiliation(s)
- Russell J. R. Barkley
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
| | - Jack C. Crowley
- School of Applied and Engineering Physics, College of Engineering, Cornell University, Ithaca, NY 14850
| | - Andrew J. Brodrick
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
| | - Warren R. Zipfel
- School of Applied and Engineering Physics, College of Engineering, Cornell University, Ithaca, NY 14850
- Meinig School of Biomedical Engineering, College of Engineering, Cornell University, Ithaca, NY 14850
| | - John S. L. Parker
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
- Baker Institute for Animal Health, College of Veterinary Medicine, Cornell University, Ithaca, NY 14850
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11
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Benchorin G, Cho RJ, Li MJ, Molotkova N, Kohwi M. Dan forms condensates in neuroblasts and regulates nuclear architecture and progenitor competence in vivo. Nat Commun 2024; 15:5097. [PMID: 38877037 PMCID: PMC11178893 DOI: 10.1038/s41467-024-49326-6] [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: 01/22/2024] [Accepted: 05/30/2024] [Indexed: 06/16/2024] Open
Abstract
Genome organization is thought to underlie cell type specific gene expression, yet how it is regulated in progenitors to produce cellular diversity is unknown. In Drosophila, a developmentally-timed genome reorganization in neural progenitors terminates competence to produce early-born neurons. These events require downregulation of Distal antenna (Dan), part of the conserved pipsqueak DNA-binding superfamily. Here we find that Dan forms liquid-like condensates with high protein mobility, and whose size and subnuclear distribution are balanced with its DNA-binding. Further, we identify a LARKS domain, a structural motif associated with condensate-forming proteins. Deleting just 13 amino acids from LARKS abrogates Dan's ability to retain the early-born neural fate gene, hunchback, in the neuroblast nuclear interior and maintain competence in vivo. Conversely, domain-swapping with LARKS from known phase-separating proteins rescues Dan's effects on competence. Together, we provide in vivo evidence for condensate formation and the regulation of progenitor nuclear architecture underlying neuronal diversification.
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Affiliation(s)
- Gillie Benchorin
- Department of Biological Sciences, Columbia University, New York, NY, USA
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
| | - Richard Jangwon Cho
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Maggie Jiaqi Li
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Natalia Molotkova
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA
- Department of Neuroscience, Columbia University, New York, NY, USA
| | - Minoree Kohwi
- Zuckerman Mind Brain Behavior Institute, Columbia University, New York, NY, USA.
- Department of Neuroscience, Columbia University, New York, NY, USA.
- Kavli Institute for Brain Science, Columbia University, New York, NY, USA.
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12
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Mathias KM, Liu Y, Wan L. Dysregulation of transcriptional condensates in human disease: mechanisms, biological functions, and open questions. Curr Opin Genet Dev 2024; 86:102203. [PMID: 38788489 PMCID: PMC11162900 DOI: 10.1016/j.gde.2024.102203] [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: 10/30/2023] [Revised: 04/18/2024] [Accepted: 04/22/2024] [Indexed: 05/26/2024]
Abstract
Precise gene expression, crucial for normal development and health, depends on the co-ordinated assembly and function of various factors within the crowded nucleus. Recent evidence suggests that this process is in part regulated by mesoscale compartmentalization and concentration of transcriptional components within condensates, offering a new perspective on gene regulation. Dysregulation of transcriptional condensates is increasingly associated with diseases, indicating a potential role in pathogenesis. In this mini-review, we provide a concise overview of the current understanding of the formation and function of transcriptional condensates, with a specific focus on recent advances in their dysregulation and implications in diseases, notably cancer. We also address limitations in the field and highlight open questions for future research.
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Affiliation(s)
- Kaeli M Mathias
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Biochemistry Biophysics Chemical Biology Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Yiman Liu
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Liling Wan
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Epigenetics Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Institute for Regenerative Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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13
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Schwenzer N, Teiwes NK, Kohl T, Pohl C, Giller MJ, Lehnart SE, Steinem C. Ca V1.3 channel clusters characterized by live-cell and isolated plasma membrane nanoscopy. Commun Biol 2024; 7:620. [PMID: 38783117 PMCID: PMC11116533 DOI: 10.1038/s42003-024-06313-3] [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: 10/23/2023] [Accepted: 05/08/2024] [Indexed: 05/25/2024] Open
Abstract
A key player of excitable cells in the heart and brain is the L-type calcium channel CaV1.3. In the heart, it is required for voltage-dependent Ca2+-signaling, i.e., for controlling and modulating atrial cardiomyocyte excitation-contraction coupling. The clustering of CaV1.3 in functionally relevant channel multimers has not been addressed due to a lack of stoichiometric labeling combined with high-resolution imaging. Here, we developed a HaloTag-labeling strategy to visualize and quantify CaV1.3 clusters using STED nanoscopy to address the questions of cluster size and intra-cluster channel density. Channel clusters were identified in the plasma membrane of transfected live HEK293 cells as well as in giant plasma membrane vesicles derived from these cells that were spread on modified glass support to obtain supported plasma membrane bilayers (SPMBs). A small fraction of the channel clusters was colocalized with early and recycling endosomes at the membranes. STED nanoscopy in conjunction with live-cell and SPMB imaging enabled us to quantify CaV1.3 cluster sizes and their molecular density revealing significantly lower channel densities than expected for dense channel packing. CaV1.3 channel cluster size and molecular density were increased in SPMBs after treatment of the cells with the sympathomimetic compound isoprenaline, suggesting a regulated channel cluster condensation mechanism.
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Affiliation(s)
- Niko Schwenzer
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Robert‑Koch‑Str. 42a, 37075, Göttingen, Germany
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC 2067), University of Göttingen, 37073, Göttingen, Germany
| | - Nikolas K Teiwes
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC 2067), University of Göttingen, 37073, Göttingen, Germany
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Tobias Kohl
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Robert‑Koch‑Str. 42a, 37075, Göttingen, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany
| | - Celine Pohl
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Michelle J Giller
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany
| | - Stephan E Lehnart
- Department of Cardiology and Pneumology, University Medical Center Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
- Cellular Biophysics and Translational Cardiology Section, Heart Research Center Göttingen, University Medical Center Göttingen, Robert‑Koch‑Str. 42a, 37075, Göttingen, Germany.
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC 2067), University of Göttingen, 37073, Göttingen, Germany.
- DZHK (German Centre for Cardiovascular Research), partner site Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.
- Collaborative Research Center SFB 1190 "Compartmental Gates and Contact Sites in Cells", University of Göttingen, Humboldtallee 23, 37073, Göttingen, Germany.
| | - Claudia Steinem
- Cluster of Excellence "Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells" (MBExC 2067), University of Göttingen, 37073, Göttingen, Germany.
- Georg-August Universität, Institut für Organische und Biomolekulare Chemie, Tammannstr. 2, 37077, Göttingen, Germany.
- Max-Planck-Institut für Dynamik und Selbstorganisation, Am Fassberg 17, 37077, Göttingen, Germany.
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14
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DeHaro-Arbona FJ, Roussos C, Baloul S, Townson J, Gómez Lamarca MJ, Bray S. Dynamic modes of Notch transcription hubs conferring memory and stochastic activation revealed by live imaging the co-activator Mastermind. eLife 2024; 12:RP92083. [PMID: 38727722 PMCID: PMC11087053 DOI: 10.7554/elife.92083] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
Developmental programming involves the accurate conversion of signalling levels and dynamics to transcriptional outputs. The transcriptional relay in the Notch pathway relies on nuclear complexes containing the co-activator Mastermind (Mam). By tracking these complexes in real time, we reveal that they promote the formation of a dynamic transcription hub in Notch ON nuclei which concentrates key factors including the Mediator CDK module. The composition of the hub is labile and persists after Notch withdrawal conferring a memory that enables rapid reformation. Surprisingly, only a third of Notch ON hubs progress to a state with nascent transcription, which correlates with polymerase II and core Mediator recruitment. This probability is increased by a second signal. The discovery that target-gene transcription is probabilistic has far-reaching implications because it implies that stochastic differences in Notch pathway output can arise downstream of receptor activation.
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Affiliation(s)
- F Javier DeHaro-Arbona
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Charalambos Roussos
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Sarah Baloul
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Jonathan Townson
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - María J Gómez Lamarca
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocıo/CSIC/Universidad de Sevilla, Departamento de Biologıa CelularSevilleSpain
| | - Sarah Bray
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
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15
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Chen J, Stephan T, Gaedke F, Liu T, Li Y, Schauss A, Chen P, Wulff V, Jakobs S, Jüngst C, Chen Z. An aldehyde-crosslinking mitochondrial probe for STED imaging in fixed cells. Proc Natl Acad Sci U S A 2024; 121:e2317703121. [PMID: 38687792 PMCID: PMC11087744 DOI: 10.1073/pnas.2317703121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 03/22/2024] [Indexed: 05/02/2024] Open
Abstract
Fluorescence labeling of chemically fixed specimens, especially immunolabeling, plays a vital role in super-resolution imaging as it offers a convenient way to visualize cellular structures like mitochondria or the distribution of biomolecules with high detail. Despite the development of various distinct probes that enable super-resolved stimulated emission depletion (STED) imaging of mitochondria in live cells, most of these membrane-potential-dependent fluorophores cannot be retained well in mitochondria after chemical fixation. This lack of suitable mitochondrial probes has limited STED imaging of mitochondria to live cell samples. In this study, we introduce a mitochondria-specific probe, PK Mito Orange FX (PKMO FX), which features a fixation-driven cross-linking motif and accumulates in the mitochondrial inner membrane. It exhibits high fluorescence retention after chemical fixation and efficient depletion at 775 nm, enabling nanoscopic imaging both before and after aldehyde fixation. We demonstrate the compatibility of this probe with conventional immunolabeling and other strategies commonly used for fluorescence labeling of fixed samples. Moreover, we show that PKMO FX facilitates correlative super-resolution light and electron microscopy, enabling the correlation of multicolor fluorescence images and transmission EM images via the characteristic mitochondrial pattern. Our probe further expands the mitochondrial toolkit for multimodal microscopy at nanometer resolutions.
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Affiliation(s)
- Jingting Chen
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing100871, China
| | - Till Stephan
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen37075, Germany
| | - Felix Gaedke
- Faculty of Mathematics and Natural Sciences, Cluster of Excellence Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne50931, Germany
| | - Tianyan Liu
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Yiyan Li
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
| | - Astrid Schauss
- Faculty of Mathematics and Natural Sciences, Cluster of Excellence Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne50931, Germany
| | - Peng Chen
- Peking University-Nanjing Institute of Translational Medicine, Nanjing211800, China
- Genvivo Biotech (PuHaiJingShan), Nanjing211800, China
| | - Veronika Wulff
- Faculty of Mathematics and Natural Sciences, Cluster of Excellence Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne50931, Germany
| | - Stefan Jakobs
- Department of NanoBiophotonics, Max Planck Institute for Multidisciplinary Sciences, Göttingen37077, Germany
- Clinic of Neurology, University Medical Center Göttingen, Göttingen37075, Germany
- Fraunhofer Institute for Translational Medicine and Pharmacology Translational, Neuroinflammation and Automated Microscopy, Göttingen37075, Germany
- Cluster of Excellence “Multiscale Bioimaging: From Molecular Machines to Networks of Excitable Cells”, University of Göttingen, Göttingen37099, Germany
| | - Christian Jüngst
- Faculty of Mathematics and Natural Sciences, Cluster of Excellence Cellular Stress Responses in Aging-associated Diseases (CECAD), University of Cologne, Cologne50931, Germany
| | - Zhixing Chen
- College of Future Technology, Institute of Molecular Medicine, National Biomedical Imaging Center, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking University, Beijing100871, China
- Peking-Tsinghua Center for Life Science, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing100871, China
- Peking University-Nanjing Institute of Translational Medicine, Nanjing211800, China
- Genvivo Biotech (PuHaiJingShan), Nanjing211800, China
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16
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Gómez Acuña LI, Flyamer I, Boyle S, Friman ET, Bickmore WA. Transcription decouples estrogen-dependent changes in enhancer-promoter contact frequencies and spatial proximity. PLoS Genet 2024; 20:e1011277. [PMID: 38781242 DOI: 10.1371/journal.pgen.1011277] [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: 11/27/2023] [Revised: 06/05/2024] [Accepted: 04/29/2024] [Indexed: 05/25/2024] Open
Abstract
How enhancers regulate their target genes in the context of 3D chromatin organization is extensively studied and models which do not require direct enhancer-promoter contact have recently emerged. Here, we use the activation of estrogen receptor-dependent enhancers in a breast cancer cell line to study enhancer-promoter communication at two loci. This allows high temporal resolution tracking of molecular events from hormone stimulation to efficient gene activation. We examine how both enhancer-promoter spatial proximity assayed by DNA fluorescence in situ hybridization, and contact frequencies resulting from chromatin in situ fragmentation and proximity ligation, change dynamically during enhancer-driven gene activation. These orthogonal methods produce seemingly paradoxical results: upon enhancer activation enhancer-promoter contact frequencies increase while spatial proximity decreases. We explore this apparent discrepancy using different estrogen receptor ligands and transcription inhibitors. Our data demonstrate that enhancer-promoter contact frequencies are transcription independent whereas altered enhancer-promoter proximity depends on transcription. Our results emphasize that the relationship between contact frequencies and physical distance in the nucleus, especially over short genomic distances, is not always a simple one.
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Affiliation(s)
- Luciana I Gómez Acuña
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road, Edinburgh, United Kingdom
| | - Ilya Flyamer
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road, Edinburgh, United Kingdom
| | - Shelagh Boyle
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road, Edinburgh, United Kingdom
| | - Elias T Friman
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road, Edinburgh, United Kingdom
| | - Wendy A Bickmore
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Crewe Road, Edinburgh, United Kingdom
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17
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Vizjak P, Kamp D, Hepp N, Scacchetti A, Gonzalez Pisfil M, Bartho J, Halic M, Becker PB, Smolle M, Stigler J, Mueller-Planitz F. ISWI catalyzes nucleosome sliding in condensed nucleosome arrays. Nat Struct Mol Biol 2024:10.1038/s41594-024-01290-x. [PMID: 38664566 DOI: 10.1038/s41594-024-01290-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 03/25/2024] [Indexed: 05/07/2024]
Abstract
How chromatin enzymes work in condensed chromatin and how they maintain diffusional mobility inside remains unexplored. Here we investigated these challenges using the Drosophila ISWI remodeling ATPase, which slides nucleosomes along DNA. Folding of chromatin fibers did not affect sliding in vitro. Catalytic rates were also comparable in- and outside of chromatin condensates. ISWI cross-links and thereby stiffens condensates, except when ATP hydrolysis is possible. Active hydrolysis is also required for ISWI's mobility in condensates. Energy from ATP hydrolysis therefore fuels ISWI's diffusion through chromatin and prevents ISWI from cross-linking chromatin. Molecular dynamics simulations of a 'monkey-bar' model in which ISWI grabs onto neighboring nucleosomes, then withdraws from one before rebinding another in an ATP hydrolysis-dependent manner, qualitatively agree with our data. We speculate that monkey-bar mechanisms could be shared with other chromatin factors and that changes in chromatin dynamics caused by mutations in remodelers could contribute to pathologies.
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Affiliation(s)
- Petra Vizjak
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Molecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Early Stage Bioprocess Development, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Dieter Kamp
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
| | - Nicola Hepp
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
- Department of Molecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Department of Clinical Genetics, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
| | - Alessandro Scacchetti
- Department of Molecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- Epigenetics Institute and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Mariano Gonzalez Pisfil
- Core Facility Bioimaging and Walter-Brendel-Centre of Experimental Medicine, Biomedical Center, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Joseph Bartho
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Mario Halic
- Department of Structural Biology, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Peter B Becker
- Department of Molecular Biology, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Michaela Smolle
- Department of Physiological Chemistry, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- BioPhysics Core Facility, Biomedical Center, Faculty of Medicine, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
- ViraTherapeutics GmbH, Rum, Austria
| | - Johannes Stigler
- Gene Center, Department of Biochemistry, Ludwig-Maximilians-Universität München, Munich, Germany.
| | - Felix Mueller-Planitz
- Institute of Physiological Chemistry, Faculty of Medicine Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany.
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18
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Li Q, Hariri S, Calidas A, Kaur A, Huey E, Engebrecht J. The chromatin-associated 53BP1 ortholog, HSR-9, regulates recombinational repair and X chromosome segregation in the Caenorhabditis elegans germ line. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.12.589267. [PMID: 38659880 PMCID: PMC11042201 DOI: 10.1101/2024.04.12.589267] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
53BP1 plays a crucial role in regulating DNA damage repair pathway choice and checkpoint signaling in somatic cells; however, its role in meiosis has remained enigmatic. In this study, we demonstrate that the Caenorhabditis elegans ortholog of 53BP1, HSR-9, associates with chromatin in both proliferating and meiotic germ cells. Notably, HSR-9 is enriched on the X chromosome pair in pachytene oogenic germ cells. HSR-9 is also present at kinetochores during both mitotic and meiotic divisions but does not appear to be essential for monitoring microtubule-kinetochore attachments or tension. Using cytological markers of different steps in recombinational repair, we found that HSR-9 influences the processing of a subset of meiotic double strand breaks into COSA-1-marked crossovers. Additionally, HSR-9 plays a role in meiotic X chromosome segregation under conditions where X chromosomes fail to pair, synapse, and recombine. Together, these results highlight that chromatin-associated HSR-9 has both conserved and unique functions in the regulation of meiotic chromosome behavior.
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Affiliation(s)
- Qianyan Li
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, California 95616
| | - Sara Hariri
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, California 95616
| | - Aashna Calidas
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
| | - Arshdeep Kaur
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
| | - Erica Huey
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
| | - JoAnne Engebrecht
- Department of Molecular and Cellular Biology, University of California Davis, Davis, California 95616
- Biochemistry, Molecular, Cellular and Developmental Biology Graduate Group, University of California Davis, Davis, California 95616
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19
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Jaiswal M, Tran TT, Guo J, Zhou M, Kundu S, Guo Z, Fanucci GE. Spin-labeling Insights into How Chemical Fixation Impacts Glycan Organization on Cells. APPLIED MAGNETIC RESONANCE 2024; 55:317-333. [PMID: 38469359 PMCID: PMC10927023 DOI: 10.1007/s00723-023-01624-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 09/21/2023] [Accepted: 09/22/2023] [Indexed: 03/13/2024]
Abstract
As new methods to interrogate glycan organization on cells develop, it is important to have a molecular level understanding of how chemical fixation can impact results and interpretations. Site-directed spin labeling technologies are well suited to study how the spin label mobility is impacted by local environmental conditions, such as those imposed by cross-linking effects of paraformaldehyde cell fixation methods. Here, we utilize three different azide-containing sugars for metabolic glycan engineering with HeLa cells to incorporate azido glycans that are modified with a DBCO-based nitroxide moiety via click reaction. Continuous wave X-band electron paramagnetic resonance spectroscopy is employed to characterize how the chronological sequence of chemical fixation and spin labeling impacts the local mobility and accessibility of the nitroxide-labeled glycans in the glycocalyx of HeLa cells. Results demonstrate that chemical fixation with paraformaldehyde can alter local glycan mobility and care should be taken in the analysis of data in any study where chemical fixation and cellular labeling occur.
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Affiliation(s)
- Mohit Jaiswal
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Trang T Tran
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Jiatong Guo
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Mingwei Zhou
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Sayan Kundu
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Zhongwu Guo
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
| | - Gail E Fanucci
- Department of Chemistry, University of Florida, 214 Leigh Hall, Gainesville, FL 32611, USA
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20
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Stortz M, Presman DM, Levi V. Transcriptional condensates: a blessing or a curse for gene regulation? Commun Biol 2024; 7:187. [PMID: 38365945 PMCID: PMC10873363 DOI: 10.1038/s42003-024-05892-5] [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: 10/26/2023] [Accepted: 02/06/2024] [Indexed: 02/18/2024] Open
Abstract
Whether phase-separation is involved in the organization of the transcriptional machinery and if it aids or inhibits the transcriptional process is a matter of intense debate. In this Mini Review, we will cover the current knowledge regarding the role of transcriptional condensates on gene expression regulation. We will summarize the latest discoveries on the relationship between condensate formation, genome organization, and transcriptional activity, focusing on the strengths and weaknesses of the experimental approaches used to interrogate these aspects of transcription in living cells. Finally, we will discuss the challenges for future research.
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Grants
- PICT 2020-00818 Ministry of Science, Technology and Productive Innovation, Argentina | Agencia Nacional de Promoción Científica y Tecnológica (National Agency for Science and Technology, Argentina)
- PICT-2018-1921 Ministry of Science, Technology and Productive Innovation, Argentina | Agencia Nacional de Promoción Científica y Tecnológica (National Agency for Science and Technology, Argentina)
- PICT 2019-0397 Ministry of Science, Technology and Productive Innovation, Argentina | Agencia Nacional de Promoción Científica y Tecnológica (National Agency for Science and Technology, Argentina)
- 20020190100101BA University of Buenos Aires | Secretaría de Ciencia y Técnica, Universidad de Buenos Aires (Secretaría de Ciencia y Técnica de la Universidad de Buenos Aires)
- 2022-11220210100212CO Consejo Nacional de Investigaciones Científicas y Técnicas (National Scientific and Technical Research Council)
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Affiliation(s)
- Martin Stortz
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina
- Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Diego M Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Buenos Aires, C1428EGA, Argentina.
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina.
| | - Valeria Levi
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina.
- Departamento de Química Biológica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, C1428EGA, Argentina.
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21
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Stein J, Ericsson M, Nofal M, Magni L, Aufmkolk S, McMillan RB, Breimann L, Herlihy CP, Lee SD, Willemin A, Wohlmann J, Arguedas-Jimenez L, Yin P, Pombo A, Church GM, Wu CK. Cryosectioning-enabled super-resolution microscopy for studying nuclear architecture at the single protein level. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.05.576943. [PMID: 38370628 PMCID: PMC10871237 DOI: 10.1101/2024.02.05.576943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
DNA-PAINT combined with total Internal Reflection Fluorescence (TIRF) microscopy enables the highest localization precisions, down to single nanometers in thin biological samples, due to TIRF's unique method for optical sectioning and attaining high contrast. However, most cellular targets elude the accessible TIRF range close to the cover glass and thus require alternative imaging conditions, affecting resolution and image quality. Here, we address this limitation by applying ultrathin physical cryosectioning in combination with DNA-PAINT. With "tomographic & kinetically-enhanced" DNA-PAINT (tokPAINT), we demonstrate the imaging of nuclear proteins with sub-3 nanometer localization precision, advancing the quantitative study of nuclear organization within fixed cells and mouse tissues at the level of single antibodies. We believe that ultrathin sectioning combined with the versatility and multiplexing capabilities of DNA-PAINT will be a powerful addition to the toolbox of quantitative DNA-based super-resolution microscopy in intracellular structural analyses of proteins, RNA and DNA in situ.
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Affiliation(s)
- Johannes Stein
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Maria Ericsson
- Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Michel Nofal
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
| | - Lorenzo Magni
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
| | - Sarah Aufmkolk
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Ryan B. McMillan
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
| | - Laura Breimann
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | | | - S. Dean Lee
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Andréa Willemin
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Humboldt-Universität zu Berlin, Institute for Biology, Berlin, Germany
| | - Jens Wohlmann
- Department of Biosciences, University of Oslo, Norway
| | - Laura Arguedas-Jimenez
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
| | - Peng Yin
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
| | - Ana Pombo
- Max-Delbrück-Center for Molecular Medicine in the Helmholtz Association (MDC), Berlin Institute for Medical Systems Biology (BIMSB), Epigenetic Regulation and Chromatin Architecture Group, Berlin, Germany
- Humboldt-Universität zu Berlin, Institute for Biology, Berlin, Germany
| | - George M. Church
- Wyss Institute of Biologically Inspired Engineering, Boston, MA, USA
- Department of Genetics, Harvard Medical School, Boston, MA, USA
| | - Chao-Kng Wu
- Department of Genetics, Harvard Medical School, Boston, MA, USA
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22
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Xiao Y, Chen YM, Zou Z, Ye C, Dou X, Wu J, Liu C, Liu S, Yan H, Wang P, Zeng TB, Liu Q, Fei J, Tang W, He C. Profiling of RNA-binding protein binding sites by in situ reverse transcription-based sequencing. Nat Methods 2024; 21:247-258. [PMID: 38200227 PMCID: PMC10864177 DOI: 10.1038/s41592-023-02146-w] [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: 03/05/2023] [Accepted: 12/07/2023] [Indexed: 01/12/2024]
Abstract
RNA-binding proteins (RBPs) regulate diverse cellular processes by dynamically interacting with RNA targets. However, effective methods to capture both stable and transient interactions between RBPs and their RNA targets are still lacking, especially when the interaction is dynamic or samples are limited. Here we present an assay of reverse transcription-based RBP binding site sequencing (ARTR-seq), which relies on in situ reverse transcription of RBP-bound RNAs guided by antibodies to identify RBP binding sites. ARTR-seq avoids ultraviolet crosslinking and immunoprecipitation, allowing for efficient and specific identification of RBP binding sites from as few as 20 cells or a tissue section. Taking advantage of rapid formaldehyde fixation, ARTR-seq enables capturing the dynamic RNA binding by RBPs over a short period of time, as demonstrated by the profiling of dynamic RNA binding of G3BP1 during stress granule assembly on a timescale as short as 10 minutes.
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Affiliation(s)
- Yu Xiao
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Yan-Ming Chen
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Zhongyu Zou
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Chang Ye
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Xiaoyang Dou
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Jinjun Wu
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
| | - Chang Liu
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Shun Liu
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Hao Yan
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
| | - Pingluan Wang
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Tie-Bo Zeng
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Qinzhe Liu
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
- Howard Hughes Medical Institute, Chicago, IL, USA
| | - Jingyi Fei
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
| | - Weixin Tang
- Department of Chemistry, The University of Chicago, Chicago, IL, USA
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA
| | - Chuan He
- Department of Chemistry, The University of Chicago, Chicago, IL, USA.
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
- Howard Hughes Medical Institute, Chicago, IL, USA.
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23
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Hsiao AS. Protein Disorder in Plant Stress Adaptation: From Late Embryogenesis Abundant to Other Intrinsically Disordered Proteins. Int J Mol Sci 2024; 25:1178. [PMID: 38256256 PMCID: PMC10816898 DOI: 10.3390/ijms25021178] [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: 10/29/2023] [Revised: 01/15/2024] [Accepted: 01/16/2024] [Indexed: 01/24/2024] Open
Abstract
Global climate change has caused severe abiotic and biotic stresses, affecting plant growth and food security. The mechanical understanding of plant stress responses is critical for achieving sustainable agriculture. Intrinsically disordered proteins (IDPs) are a group of proteins without unique three-dimensional structures. The environmental sensitivity and structural flexibility of IDPs contribute to the growth and developmental plasticity for sessile plants to deal with environmental challenges. This article discusses the roles of various disordered proteins in plant stress tolerance and resistance, describes the current mechanistic insights into unstructured proteins such as the disorder-to-order transition for adopting secondary structures to interact with specific partners (i.e., cellular membranes, membrane proteins, metal ions, and DNA), and elucidates the roles of liquid-liquid phase separation driven by protein disorder in stress responses. By comparing IDP studies in animal systems, this article provides conceptual principles of plant protein disorder in stress adaptation, reveals the current research gaps, and advises on the future research direction. The highlighting of relevant unanswered questions in plant protein disorder research aims to encourage more studies on these emerging topics to understand the mechanisms of action behind their stress resistance phenotypes.
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Affiliation(s)
- An-Shan Hsiao
- Department of Biochemistry and Metabolism, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK
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24
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Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling Difficult Cryo-ET Samples: A Study with Primary Neurons from Drosophila melanogaster. MICROSCOPY AND MICROANALYSIS : THE OFFICIAL JOURNAL OF MICROSCOPY SOCIETY OF AMERICA, MICROBEAM ANALYSIS SOCIETY, MICROSCOPICAL SOCIETY OF CANADA 2023; 29:2127-2148. [PMID: 37966978 PMCID: PMC11168236 DOI: 10.1093/micmic/ozad125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 10/01/2023] [Accepted: 10/18/2023] [Indexed: 11/17/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons having been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
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Affiliation(s)
- Joseph Y. Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Jie E. Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Josephine W. Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI 49006, USA
| | - Lauren A. English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Sihui Z. Yang
- Department of Biology, Stanford University, Stanford, CA 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI 53715, USA
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25
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Medwig-Kinney TN, Kinney BA, Martinez MAQ, Yee C, Sirota SS, Mullarkey AA, Somineni N, Hippler J, Zhang W, Shen K, Hammell C, Pani AM, Matus DQ. Dynamic compartmentalization of the pro-invasive transcription factor NHR-67 reveals a role for Groucho in regulating a proliferative-invasive cellular switch in C. elegans. eLife 2023; 12:RP84355. [PMID: 38038410 PMCID: PMC10691804 DOI: 10.7554/elife.84355] [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] [Indexed: 12/02/2023] Open
Abstract
A growing body of evidence suggests that cell division and basement membrane invasion are mutually exclusive cellular behaviors. How cells switch between proliferative and invasive states is not well understood. Here, we investigated this dichotomy in vivo by examining two cell types in the developing Caenorhabditis elegans somatic gonad that derive from equipotent progenitors, but exhibit distinct cell behaviors: the post-mitotic, invasive anchor cell and the neighboring proliferative, non-invasive ventral uterine (VU) cells. We show that the fates of these cells post-specification are more plastic than previously appreciated and that levels of NHR-67 are important for discriminating between invasive and proliferative behavior. Transcription of NHR-67 is downregulated following post-translational degradation of its direct upstream regulator, HLH-2 (E/Daughterless) in VU cells. In the nuclei of VU cells, residual NHR-67 protein is compartmentalized into discrete punctae that are dynamic over the cell cycle and exhibit liquid-like properties. By screening for proteins that colocalize with NHR-67 punctae, we identified new regulators of uterine cell fate maintenance: homologs of the transcriptional co-repressor Groucho (UNC-37 and LSY-22), as well as the TCF/LEF homolog POP-1. We propose a model in which the association of NHR-67 with the Groucho/TCF complex suppresses the default invasive state in non-invasive cells, which complements transcriptional regulation to add robustness to the proliferative-invasive cellular switch in vivo.
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Affiliation(s)
- Taylor N Medwig-Kinney
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Brian A Kinney
- Cold Spring Harbor LaboratoryCold Spring HarborUnited States
| | - Michael AQ Martinez
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Callista Yee
- Howard Hughes Medical Institute, Department of Biology, Stanford UniversityStanfordUnited States
| | - Sydney S Sirota
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Angelina A Mullarkey
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Neha Somineni
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Justin Hippler
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
- Science and Technology Research Program, Smithtown High School EastSt. JamesUnited States
| | - Wan Zhang
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
| | - Kang Shen
- Howard Hughes Medical Institute, Department of Biology, Stanford UniversityStanfordUnited States
| | | | - Ariel M Pani
- Departments of Biology and Cell Biology, University of VirginiaCharlottesvilleUnited States
| | - David Q Matus
- Department of Biochemistry and Cell Biology, Stony Brook UniversityStony BrookUnited States
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26
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Demmerle J, Hao S, Cai D. Transcriptional condensates and phase separation: condensing information across scales and mechanisms. Nucleus 2023; 14:2213551. [PMID: 37218279 PMCID: PMC10208215 DOI: 10.1080/19491034.2023.2213551] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 04/26/2023] [Accepted: 05/10/2023] [Indexed: 05/24/2023] Open
Abstract
Transcription is the fundamental process of gene expression, which in eukaryotes occurs within the complex physicochemical environment of the nucleus. Decades of research have provided extreme detail in the molecular and functional mechanisms of transcription, but the spatial and genomic organization of transcription remains mysterious. Recent discoveries show that transcriptional components can undergo phase separation and create distinct compartments inside the nucleus, providing new models through which to view the transcription process in eukaryotes. In this review, we focus on transcriptional condensates and their phase separation-like behaviors. We suggest differentiation between physical descriptions of phase separation and the complex and dynamic biomolecular assemblies required for productive gene expression, and we discuss how transcriptional condensates are central to organizing the three-dimensional genome across spatial and temporal scales. Finally, we map approaches for therapeutic manipulation of transcriptional condensates and ask what technical advances are needed to understand transcriptional condensates more completely.
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Affiliation(s)
- Justin Demmerle
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Siyuan Hao
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
| | - Danfeng Cai
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD, USA
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27
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Louvel V, Haase R, Mercey O, Laporte MH, Eloy T, Baudrier É, Fortun D, Soldati-Favre D, Hamel V, Guichard P. iU-ExM: nanoscopy of organelles and tissues with iterative ultrastructure expansion microscopy. Nat Commun 2023; 14:7893. [PMID: 38036510 PMCID: PMC10689735 DOI: 10.1038/s41467-023-43582-8] [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: 11/21/2022] [Accepted: 11/14/2023] [Indexed: 12/02/2023] Open
Abstract
Expansion microscopy (ExM) is a highly effective technique for super-resolution fluorescence microscopy that enables imaging of biological samples beyond the diffraction limit with conventional fluorescence microscopes. Despite the development of several enhanced protocols, ExM has not yet demonstrated the ability to achieve the precision of nanoscopy techniques such as Single Molecule Localization Microscopy (SMLM). Here, to address this limitation, we have developed an iterative ultrastructure expansion microscopy (iU-ExM) approach that achieves SMLM-level resolution. With iU-ExM, it is now possible to visualize the molecular architecture of gold-standard samples, such as the eight-fold symmetry of nuclear pores or the molecular organization of the conoid in Apicomplexa. With its wide-ranging applications, from isolated organelles to cells and tissue, iU-ExM opens new super-resolution avenues for scientists studying biological structures and functions.
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Affiliation(s)
- Vincent Louvel
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Romuald Haase
- Department of Microbiology and Molecular medicine, University of Geneva, Geneva, Switzerland
| | - Olivier Mercey
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Marine H Laporte
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland
| | - Thibaut Eloy
- ICube - UMR7357, CNRS, University of Strasbourg, Strasbourg, France
| | - Étienne Baudrier
- ICube - UMR7357, CNRS, University of Strasbourg, Strasbourg, France
| | - Denis Fortun
- ICube - UMR7357, CNRS, University of Strasbourg, Strasbourg, France
| | - Dominique Soldati-Favre
- Department of Microbiology and Molecular medicine, University of Geneva, Geneva, Switzerland
| | - Virginie Hamel
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
| | - Paul Guichard
- Department of Molecular and Cellular Biology, University of Geneva, Geneva, Switzerland.
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28
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Yu TG, Lee J, Yoon J, Choi JM, Kim DG, Heo WD, Song JJ, Kim HS. Engineering of a Fluorescent Protein for a Sensing of an Intrinsically Disordered Protein through Transition in the Chromophore State. JACS AU 2023; 3:3055-3065. [PMID: 38034956 PMCID: PMC10685427 DOI: 10.1021/jacsau.3c00445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/05/2023] [Revised: 09/18/2023] [Accepted: 10/02/2023] [Indexed: 12/02/2023]
Abstract
Intrinsically disordered proteins (IDPs) not only play important roles in biological processes but are also linked with the pathogenesis of various human diseases. Specific and reliable sensing of IDPs is crucial for exploring their roles but remains elusive due to structural plasticity. Here, we present the development of a new type of fluorescent protein for the ratiometric sensing and tracking of an IDP. A β-strand of green fluorescent protein (GFP) was truncated, and the resulting GFP was further engineered to undergo the transition in the absorption maximum upon binding of a target motif within amyloid-β (Aβ) as a model IDP through rational design and directed evolution. Spectroscopic and structural analyses of the engineered truncated GFP demonstrated that a shift in the absorption maximum is driven by the change in the chromophore state from an anionic (460 nm) state into a neutral (390 nm) state as the Aβ binds, allowing a ratiometric detection of Aβ. The utility of the developed GFP was shown by the efficient and specific detection of an Aβ and the tracking of its conformational change and localization in astrocytes.
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Affiliation(s)
- Tae-Geun Yu
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jinsu Lee
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jungmin Yoon
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Jung Min Choi
- School
of Food Biotechnology and Nutrition, Kyungsung
University, Busan 48434, Korea
| | - Dong-Gun Kim
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Won Do Heo
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Ji-Joon Song
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
| | - Hak-Sung Kim
- Departement
of Biological Sciences, Korea Advanced Institute
of Science and Technology (KAIST), Daejeon 34141, Korea
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29
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Zhang X, Xiao Q, Zeng L, Hashmi F, Su X. IDR-induced CAR condensation improves the cytotoxicity of CAR-Ts against low-antigen cancers. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.02.560460. [PMID: 37873222 PMCID: PMC10592880 DOI: 10.1101/2023.10.02.560460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Chimeric antigen receptor (CAR)-T cell-based therapies demonstrate remarkable efficacy for the treatment of otherwise intractable cancers, particularly B-cell malignancies. However, existing FDA-approved CAR-Ts are limited by low antigen sensitivity, rendering their insufficient targeting to low antigen-expressing cancers. To improve the antigen sensitivity of CAR-Ts, we engineered CARs targeting CD19, CD22, and HER2 by including intrinsically disordered regions (IDRs) that promote signaling condensation. The "IDR CARs" triggered enhanced membrane-proximal signaling in the CAR-T synapse, which led to an increased release of cytotoxic factors, a higher killing activity towards low antigen-expressing cancer cells in vitro, and an improved anti-tumor efficacy in vivo. No elevated tonic signaling was observed in IDR CAR-Ts. Together, we demonstrated IDRs as a new tool set to enhance CAR-T cytotoxicity and to broaden CAR-T's application to low antigen-expressing cancers.
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Affiliation(s)
- Xinyan Zhang
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Qian Xiao
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Longhui Zeng
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
| | - Fawzaan Hashmi
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
- Yale College, New Haven, CT 06520
| | - Xiaolei Su
- Department of Cell Biology, Yale School of Medicine, New Haven, CT 06520
- Yale Cancer Center, New Haven, CT 06520
- Yale Stem Cell Center, New Haven, CT 06520
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30
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Kind L, Driver M, Raasakka A, Onck PR, Njølstad PR, Arnesen T, Kursula P. Structural properties of the HNF-1A transactivation domain. Front Mol Biosci 2023; 10:1249939. [PMID: 37908230 PMCID: PMC10613711 DOI: 10.3389/fmolb.2023.1249939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 09/26/2023] [Indexed: 11/02/2023] Open
Abstract
Hepatocyte nuclear factor 1α (HNF-1A) is a transcription factor with important gene regulatory roles in pancreatic β-cells. HNF1A gene variants are associated with a monogenic form of diabetes (HNF1A-MODY) or an increased risk for type 2 diabetes. While several pancreatic target genes of HNF-1A have been described, a lack of knowledge regarding the structure-function relationships in HNF-1A prohibits a detailed understanding of HNF-1A-mediated gene transcription, which is important for precision medicine and improved patient care. Therefore, we aimed to characterize the understudied transactivation domain (TAD) of HNF-1A in vitro. We present a bioinformatic approach to dissect the TAD sequence, analyzing protein structure, sequence composition, sequence conservation, and the existence of protein interaction motifs. Moreover, we developed the first protocol for the recombinant expression and purification of the HNF-1A TAD. Small-angle X-ray scattering and synchrotron radiation circular dichroism suggested a disordered conformation for the TAD. Furthermore, we present functional data on HNF-1A undergoing liquid-liquid phase separation, which is in line with in silico predictions and may be of biological relevance for gene transcriptional processes in pancreatic β-cells.
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Affiliation(s)
- Laura Kind
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Mark Driver
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Arne Raasakka
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Patrick R. Onck
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Pål Rasmus Njølstad
- Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
- Section of Endocrinology and Metabolism, Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Surgery, Haukeland University Hospital, Bergen, Norway
| | - Petri Kursula
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
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31
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Ries RJ, Pickering BF, Poh HX, Namkoong S, Jaffrey SR. m 6A governs length-dependent enrichment of mRNAs in stress granules. Nat Struct Mol Biol 2023; 30:1525-1535. [PMID: 37710015 DOI: 10.1038/s41594-023-01089-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/04/2023] [Indexed: 09/16/2023]
Abstract
Stress granules are biomolecular condensates composed of protein and mRNA. One feature of stress granule-enriched mRNAs is that they are often longer than average. Another feature of stress granule-enriched mRNAs is that they often contain multiple N6-methyladenosine (m6A) residues. m6A is bound by the YTHDF proteins, creating mRNA-protein complexes that partition into stress granules in mammalian cells. Here we show that length-dependent enrichment of mRNAs in stress granules is mediated by m6A. Long mRNAs often contain one or more long exons, which are preferential sites of m6A formation. In mammalian cells lacking m6A, long mRNAs no longer show preferential stress granule enrichment. Furthermore, we show that m6A abundance more strongly predicts which short or long mRNAs are enriched in stress granules, rather than length alone. Thus, mRNA length correlates with mRNA enrichment in stress granules owing to the high prevalence of m6A in long mRNAs.
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Affiliation(s)
- Ryan J Ries
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Brian F Pickering
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Hui Xian Poh
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA
| | - Sim Namkoong
- Department of Biochemistry, College of Natural Sciences, Kangwon National University, Chuncheon, Republic of Korea
| | - Samie R Jaffrey
- Department of Pharmacology, Weill Cornell Medicine, Cornell University, New York, NY, USA.
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Feng L, Barrows D, Zhong L, Mätlik K, Porter EG, Djomo AM, Yau I, Soshnev AA, Carroll TS, Wen D, Hatten ME, Garcia BA, Allis CD. Altered chromatin occupancy of patient-associated H4 mutants misregulate neuronal differentiation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.29.560141. [PMID: 37808786 PMCID: PMC10557780 DOI: 10.1101/2023.09.29.560141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/10/2023]
Abstract
Chromatin is a crucial regulator of gene expression and tightly controls development across species. Mutations in only one copy of multiple histone genes were identified in children with developmental disorders characterized by microcephaly, but their mechanistic roles in development remain unclear. Here we focus on dominant mutations affecting histone H4 lysine 91. These H4K91 mutants form aberrant nuclear puncta at specific heterochromatin regions. Mechanistically, H4K91 mutants demonstrate enhanced binding to the histone variant H3.3, and ablation of H3.3 or the H3.3-specific chaperone DAXX diminishes the mutant localization to chromatin. Our functional studies demonstrate that H4K91 mutant expression increases chromatin accessibility, alters developmental gene expression through accelerating pro-neural differentiation, and causes reduced mouse brain size in vivo, reminiscent of the microcephaly phenotypes of patients. Together, our studies unveil a distinct molecular pathogenic mechanism from other known histone mutants, where H4K91 mutants misregulate cell fate during development through abnormal genomic localization.
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Affiliation(s)
- Lijuan Feng
- The Rockefeller University, Laboratory of Chromatin Biology and Epigenetics, New York, NY
| | - Douglas Barrows
- The Rockefeller University, Bioinformatics Resource Center, New York, NY
| | - Liangwen Zhong
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY
| | - Kärt Mätlik
- The Rockefeller University, Laboratory of Developmental Neurobiology, New York, NY
| | - Elizabeth G. Porter
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - Annaelle M. Djomo
- The Rockefeller University, Laboratory of Chromatin Biology and Epigenetics, New York, NY
| | - Iris Yau
- The Rockefeller University, Laboratory of Chromatin Biology and Epigenetics, New York, NY
- Hunter College of the City University of New York, Yalow Honors Scholar Program, New York, NY
| | - Alexey A. Soshnev
- The Rockefeller University, Laboratory of Chromatin Biology and Epigenetics, New York, NY
- Department of Neuroscience, Developmental and Regenerative Biology, The University of Texas at San Antonio, San Antonio, TX
| | - Thomas S. Carroll
- The Rockefeller University, Bioinformatics Resource Center, New York, NY
| | - Duancheng Wen
- Ronald O. Perelman and Claudia Cohen Center for Reproductive Medicine, Weill Cornell Medicine, New York, NY
| | - Mary E. Hatten
- The Rockefeller University, Laboratory of Developmental Neurobiology, New York, NY
| | - Benjamin A. Garcia
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO
| | - C. David Allis
- The Rockefeller University, Laboratory of Chromatin Biology and Epigenetics, New York, NY
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Idziak A, Inavalli VVGK, Bancelin S, Arizono M, Nägerl UV. The Impact of Chemical Fixation on the Microanatomy of Mouse Organotypic Hippocampal Slices. eNeuro 2023; 10:ENEURO.0104-23.2023. [PMID: 37709524 PMCID: PMC10521345 DOI: 10.1523/eneuro.0104-23.2023] [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: 03/26/2023] [Revised: 07/26/2023] [Accepted: 07/28/2023] [Indexed: 09/16/2023] Open
Abstract
Chemical fixation using paraformaldehyde (PFA) is a standard step for preserving cells and tissues for subsequent microscopic analyses such as immunofluorescence or electron microscopy (EM). However, chemical fixation may introduce physical alterations in the spatial arrangement of cellular proteins, organelles, and membranes. With the increasing use of super-resolution microscopy to visualize cellular structures with nanometric precision, assessing potential artifacts, and knowing how to avoid them, takes on special urgency. We addressed this issue by taking advantage of live-cell super-resolution microscopy that makes it possible to directly observe the acute effects of PFA on organotypic hippocampal brain slices, allowing us to compare tissue integrity in a "before-and-after" experiment. We applied super-resolution shadow imaging (SUSHI) to assess the structure of the extracellular space (ECS) and regular super-resolution microscopy of fluorescently labeled neurons and astrocytes to quantify key neuroanatomical parameters. While the ECS volume fraction (VF) and microanatomic organization of astrocytes remained largely unaffected by the PFA treatment, we detected subtle changes in dendritic spine morphology and observed substantial damage to cell membranes. Our experiments show that PFA application via immersion does not cause a noticeable shrinkage of the ECS in hippocampal brain slices maintained in culture, unlike the situation in transcardially perfused animals in vivo where the ECS typically becomes nearly depleted. Our study outlines an experimental strategy to evaluate the quality and pitfalls of various fixation protocols for the molecular and morphologic preservation of cells and tissues.
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Affiliation(s)
- Agata Idziak
- Unité Mixte de Recherche 5297, Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, University of Bordeaux, Bordeaux F-33000, France
| | - V V G Krishna Inavalli
- Unité Mixte de Recherche 5297, Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, University of Bordeaux, Bordeaux F-33000, France
| | - Stéphane Bancelin
- Unité Mixte de Recherche 5297, Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, University of Bordeaux, Bordeaux F-33000, France
| | - Misa Arizono
- Unité Mixte de Recherche 5297, Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, University of Bordeaux, Bordeaux F-33000, France
- Department of Pharmacology, Kyoto University Graduate School of Medicine/The Hakubi Center for Advanced Research, Kyoto University, Kyoto 606-8501, Japan
| | - U Valentin Nägerl
- Unité Mixte de Recherche 5297, Interdisciplinary Institute for Neuroscience, Centre National de la Recherche Scientifique, University of Bordeaux, Bordeaux F-33000, France
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Barwell T, Raina S, Page A, MacCharles H, Seroude L. Juvenile and adult expression of polyglutamine expanded huntingtin produce distinct aggregate distributions in Drosophila muscle. Hum Mol Genet 2023; 32:2656-2668. [PMID: 37369041 DOI: 10.1093/hmg/ddad098] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Revised: 05/09/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
While Huntington's disease (HD) is widely recognized as a disease affecting the nervous system, much evidence has accumulated to suggest peripheral or non-neuronal tissues are affected as well. Here, we utilize the UAS/GAL4 system to express a pathogenic HD construct in the muscle of the fly and characterize the effects. We observe detrimental phenotypes such as a reduced lifespan, decreased locomotion and accumulation of protein aggregates. Strikingly, depending on the GAL4 driver used to express the construct, we saw different aggregate distributions and severity of phenotypes. These different aggregate distributions were found to be dependent on the expression level and the timing of expression. Hsp70, a well-documented suppressor of polyglutamine aggregates, was found to strongly reduce the accumulation of aggregates in the eye, but in the muscle, it did not prevent the reduction of the lifespan. Therefore, the molecular mechanisms underlying the detrimental effects of aggregates in the muscle are distinct from the nervous system.
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Affiliation(s)
- Taylor Barwell
- Department of Biology, Queen's University, 116 Barrie St, Kingston, Ontario, K7L 3N6, Canada
| | - Sehaj Raina
- Department of Biology, Queen's University, 116 Barrie St, Kingston, Ontario, K7L 3N6, Canada
| | - Austin Page
- Department of Biology, Queen's University, 116 Barrie St, Kingston, Ontario, K7L 3N6, Canada
| | - Hayley MacCharles
- Department of Biology, Queen's University, 116 Barrie St, Kingston, Ontario, K7L 3N6, Canada
| | - Laurent Seroude
- Department of Biology, Queen's University, 116 Barrie St, Kingston, Ontario, K7L 3N6, Canada
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Ochiai H, Ohishi H, Sato Y, Kimura H. Organization of transcription and 3D genome as revealed by live-cell imaging. Curr Opin Struct Biol 2023; 81:102615. [PMID: 37257205 DOI: 10.1016/j.sbi.2023.102615] [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: 01/24/2023] [Revised: 04/03/2023] [Accepted: 05/01/2023] [Indexed: 06/02/2023]
Abstract
Higher-order genomic structures play a critical role in regulating gene expression by influencing the spatial proximity of promoters and enhancers. Live-cell imaging studies have demonstrated that three-dimensional genome structures undergo dynamic changes over time. Transcription is also dynamic, with genes frequently switching between active and inactive states. Recent observations suggest that the formation of condensates, composed of transcription-related factors, RNA, and RNA-binding proteins, around genes can regulate transcription. Advancements in technology have facilitated the visualization of the intricate spatiotemporal relationship between higher-order genomic structures, condensate formation, and transcriptional activity in living cells.
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Affiliation(s)
- Hiroshi Ochiai
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-0054, Japan.
| | - Hiroaki Ohishi
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, 812-0054, Japan
| | - Yuko Sato
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan; Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503, Japan
| | - Hiroshi Kimura
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, 226-8501, Japan; Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, 226-8503, Japan.
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Oses C, De Rossi MC, Bruno L, Verneri P, Diaz MC, Benítez B, Guberman A, Levi V. From the membrane to the nucleus: mechanical signals and transcription regulation. Biophys Rev 2023; 15:671-683. [PMID: 37681098 PMCID: PMC10480138 DOI: 10.1007/s12551-023-01103-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 07/20/2023] [Indexed: 09/09/2023] Open
Abstract
Mechanical forces drive and modulate a wide variety of processes in eukaryotic cells including those occurring in the nucleus. Relevantly, forces are fundamental during development since they guide lineage specifications of embryonic stem cells. A sophisticated macromolecular machinery transduces mechanical stimuli received at the cell surface into a biochemical output; a key component in this mechanical communication is the cytoskeleton, a complex network of biofilaments in constant remodeling that links the cell membrane to the nuclear envelope. Recent evidence highlights that forces transmitted through the cytoskeleton directly affect the organization of chromatin and the accessibility of transcription-related molecules to their targets in the DNA. Consequently, mechanical forces can directly modulate transcription and change gene expression programs. Here, we will revise the biophysical toolbox involved in the mechanical communication with the cell nucleus and discuss how mechanical forces impact on the organization of this organelle and more specifically, on transcription. We will also discuss how live-cell fluorescence imaging is producing exquisite information to understand the mechanical response of cells and to quantify the landscape of interactions of transcription factors with chromatin in embryonic stem cells. These studies are building new biophysical insights that could be fundamental to achieve the goal of manipulating forces to guide cell differentiation in culture systems.
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Affiliation(s)
- Camila Oses
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - María Cecilia De Rossi
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - Luciana Bruno
- Facultad de Ciencias Exactas Y Naturales, Instituto de Cálculo (IC), CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - Paula Verneri
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - María Candelaria Diaz
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - Belén Benítez
- Instituto de Fisiología, Biología Molecular Y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
| | - Alejandra Guberman
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
- Facultad de Ciencias Exactas Y Naturales, Departamento de Fisiología, Universidad de Buenos Aires, Biología Molecular Y Celular, C1428EGA Buenos Aires, Argentina
| | - Valeria Levi
- Instituto de Química Biológica de La Facultad de Ciencias Exactas Y Naturales (IQUIBICEN), Facultad de Ciencias Exactas Y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
- Facultad de Ciencias Exactas Y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, C1428EGA Buenos Aires, Argentina
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Al-Refaie N, Padovani F, Binando F, Hornung J, Zhao Q, Towbin BD, Cenik ES, Stroustrup N, Schmoller KM, Cabianca DS. An mTOR/RNA pol I axis shapes chromatin architecture in response to fasting. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.22.550032. [PMID: 37503059 PMCID: PMC10370172 DOI: 10.1101/2023.07.22.550032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Chromatin architecture is a fundamental mediator of genome function. Fasting is a major environmental cue across the animal kingdom. Yet, how it impacts on 3D genome organization is unknown. Here, we show that fasting induces a reversible and large-scale spatial reorganization of chromatin in C. elegans . This fasting-induced 3D genome reorganization requires inhibition of the nutrient-sensing mTOR pathway, a major regulator of ribosome biogenesis. Remarkably, loss of transcription by RNA Pol I, but not RNA Pol II nor Pol III, induces a similar 3D genome reorganization in fed animals, and prevents the restoration of the fed-state architecture upon restoring nutrients to fasted animals. Our work documents the first large-scale chromatin reorganization triggered by fasting and reveals that mTOR and RNA Pol I shape genome architecture in response to nutrients.
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38
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Fang J, Castillon G, Phan S, McArdle S, Hariharan C, Adams A, Ellisman MH, Deniz AA, Saphire EO. Spatial and functional arrangement of Ebola virus polymerase inside phase-separated viral factories. Nat Commun 2023; 14:4159. [PMID: 37443171 PMCID: PMC10345124 DOI: 10.1038/s41467-023-39821-7] [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: 12/21/2022] [Accepted: 06/29/2023] [Indexed: 07/15/2023] Open
Abstract
Ebola virus (EBOV) infection induces the formation of membrane-less, cytoplasmic compartments termed viral factories, in which multiple viral proteins gather and coordinate viral transcription, replication, and assembly. Key to viral factory function is the recruitment of EBOV polymerase, a multifunctional machine that mediates transcription and replication of the viral RNA genome. We show that intracellularly reconstituted EBOV viral factories are biomolecular condensates, with composition-dependent internal exchange dynamics that likely facilitates viral replication. Within the viral factory, we found the EBOV polymerase clusters into foci. The distance between these foci increases when viral replication is enabled. In addition to the typical droplet-like viral factories, we report the formation of network-like viral factories during EBOV infection. Unlike droplet-like viral factories, network-like factories are inactive for EBOV nucleocapsid assembly. This unique view of EBOV propagation suggests a form-to-function relationship that describes how physical properties and internal structures of biomolecular condensates influence viral biogenesis.
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Affiliation(s)
- Jingru Fang
- La Jolla Institute for Immunology, La Jolla, CA, USA
- Scripps Research, La Jolla, CA, USA
| | - Guillaume Castillon
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, CA, USA
| | - Sara McArdle
- La Jolla Institute for Immunology, La Jolla, CA, USA
| | | | - Aiyana Adams
- La Jolla Institute for Immunology, La Jolla, CA, USA
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, Center for Research in Biological Systems, Department of Neurosciences, University of California San Diego, School of Medicine, La Jolla, CA, USA
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Kim JY, Yang JE, Mitchell JW, English LA, Yang SZ, Tenpas T, Dent EW, Wildonger J, Wright ER. Handling difficult cryo-ET samples: A study with primary neurons from Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.10.548468. [PMID: 37502991 PMCID: PMC10369871 DOI: 10.1101/2023.07.10.548468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
Cellular neurobiology has benefited from recent advances in the field of cryo-electron tomography (cryo-ET). Numerous structural and ultrastructural insights have been obtained from plunge-frozen primary neurons cultured on electron microscopy grids. With most primary neurons been derived from rodent sources, we sought to expand the breadth of sample availability by using primary neurons derived from 3rd instar Drosophila melanogaster larval brains. Ultrastructural abnormalities were encountered while establishing this model system for cryo-ET, which were exemplified by excessive membrane blebbing and cellular fragmentation. To optimize neuronal samples, we integrated substrate selection, micropatterning, montage data collection, and chemical fixation. Efforts to address difficulties in establishing Drosophila neurons for future cryo-ET studies in cellular neurobiology also provided insights that future practitioners can use when attempting to establish other cell-based model systems.
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Affiliation(s)
- Joseph Y. Kim
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Jie E. Yang
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
| | - Josephine W. Mitchell
- Department of Chemistry and Biochemistry, Kalamazoo College, Kalamazoo, MI, 49006, USA
| | - Lauren A. English
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Sihui Z. Yang
- Department of Biology, Stanford University, Stanford, CA, 94305, USA
| | - Tanner Tenpas
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Erik W. Dent
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Jill Wildonger
- Departments of Pediatrics and Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Elizabeth R. Wright
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
- Cryo-Electron Microscopy Research Center, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Midwest Center for Cryo-Electron Tomography, Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, 53706, USA
- Morgridge Institute for Research, University of Wisconsin-Madison, Madison, WI, 53715, USA
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40
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Ouyang X, Wang X, Li P, Huang Q, Zhou L, Li J, Gao L, Sun Q, Chai F, Guo S, Zhou Z, Liu X, Dai L, Cheng W, Ren H. Bacterial effector restricts liquid-liquid phase separation of ZPR1 to antagonize host UPR ER. Cell Rep 2023; 42:112700. [PMID: 37379216 DOI: 10.1016/j.celrep.2023.112700] [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: 09/06/2022] [Revised: 04/29/2023] [Accepted: 06/09/2023] [Indexed: 06/30/2023] Open
Abstract
How pathogens manipulate host UPRER to mediate immune evasion is largely unknown. Here, we identify the host zinc finger protein ZPR1 as an interacting partner of the enteropathogenic E. coli (EPEC) effector NleE using proximity-enabled protein crosslinking. We show that ZPR1 assembles via liquid-liquid phase separation (LLPS) in vitro and regulates CHOP-mediated UPRER at the transcriptional level. Interestingly, in vitro studies show that the ZPR1 binding ability with K63-ubiquitin chains, which promotes LLPS of ZPR1, is disrupted by NleE. Further analyses indicate that EPEC restricts host UPRER pathways at the transcription level in a NleE-ZPR1 cascade-dependent manner. Together, our study reveals the mechanism by which EPEC interferes with CHOP-UPRER via regulating ZPR1 to help pathogens escape host defense.
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Affiliation(s)
- Xiaoxiao Ouyang
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xueyun Wang
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Pan Li
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Qin Huang
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Li Zhou
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Jingxiang Li
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Li Gao
- Department of General Practice and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, and Sichuan University, Chengdu 610041, China
| | - Qi Sun
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Fangni Chai
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Shupan Guo
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Zhihui Zhou
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Xin Liu
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China
| | - Lunzhi Dai
- Department of General Practice and National Clinical Research Center for Geriatrics, State Key Laboratory of Biotherapy, West China Hospital, and Sichuan University, Chengdu 610041, China
| | - Wei Cheng
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China; Collaborative Innovation Center of Biotherapy, Sichuan University West China Hospital, Chengdu, Sichuan 610041, China
| | - Haiyan Ren
- Department of Pulmonary and Critical Care, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu, Sichuan 610041, China; Collaborative Innovation Center of Biotherapy, Sichuan University West China Hospital, Chengdu, Sichuan 610041, China.
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41
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Jaiswal M, Tran TT, Guo J, Zhou M, Kunda S, Guo Z, Fanucci G. Spin-labeling Insights into How Chemical Fixation Impacts Glycan Organization on Cells. RESEARCH SQUARE 2023:rs.3.rs-3039983. [PMID: 37398188 PMCID: PMC10312935 DOI: 10.21203/rs.3.rs-3039983/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
As new methods to interrogate glycan organization on cells develop, it is important to have a molecular level understanding of how chemical fixation can impact results and interpretations. Site-directed spin labeling technologies are well suited to study how the spin label mobility is impacted by local environmental conditions, such as those imposed by cross-linking effects of paraformaldehyde cell fixation methods. Here, we utilize three different azide-containing sugars for metabolic glycan engineering with HeLa cells to incorporate azido glycans that are modified with a DBCO-based nitroxide moiety via click reaction. Continuous wave X-band electron paramagnetic resonance spectroscopy is employed to characterize how the chronological sequence of chemical fixation and spin labeling impacts the local mobility and accessibility of the nitroxide-labeled glycans in the glycocalyx of HeLa cells. Results demonstrate that chemical fixation with paraformaldehyde can alter local glycan mobility and care should be taken in the analysis of data in any study where chemical fixation and cellular labeling occur.
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Yoshida SR, Maity BK, Chong S. Visualizing Protein Localizations in Fixed Cells: Caveats and the Underlying Mechanisms. J Phys Chem B 2023; 127:4165-4173. [PMID: 37161904 DOI: 10.1021/acs.jpcb.3c01658] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Fluorescence microscopy techniques have been widely adopted in biology for their ability to visualize the structure and dynamics of a wide range of cellular and subcellular processes. The specificity and sensitivity that these techniques afford have made them primary tools in the characterization of protein localizations within cells. Many of the fluorescence microscopy techniques require cells to be fixed via chemical or alternative methods before being imaged. However, some fixation methods have been found to induce the redistribution of particular proteins in the cell, resulting in artifacts in the characterization of protein localizations and functions under physiological conditions. Here, we review the ability of commonly used cell fixation methods to faithfully preserve the localizations of proteins that bind to chromatin, undergo liquid-liquid phase separation (LLPS), and are involved in the formation of various membrane-bound organelles. We also review the mechanisms underlying various fixation artifacts and discuss potential alternative fixation methods to minimize the artifacts while investigating different proteins and cellular structures. Overall, fixed-cell fluorescence microscopy is a very powerful tool in biomedical research; however, each experiment demands the careful selection of an appropriate fixation method to avoid potential artifacts and may benefit from live-cell imaging validation.
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Affiliation(s)
- Shawn R Yoshida
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Barun K Maity
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
| | - Shasha Chong
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, United States
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Thuma J, Chung YC, Tu LC. Advances and challenges in CRISPR-based real-time imaging of dynamic genome organization. Front Mol Biosci 2023; 10:1173545. [PMID: 37065447 PMCID: PMC10102487 DOI: 10.3389/fmolb.2023.1173545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Accepted: 03/23/2023] [Indexed: 04/03/2023] Open
Abstract
Nuclear chromosome compaction is non-random and dynamic. The spatial distance among genomic elements instantly modulates transcription. Visualization of the genome organization in the cell nucleus is essential to understand nuclear function. In addition to cell type-dependent organization, high-resolution 3D imaging shows heterogeneous compaction of chromatin organization among the same cell type. Questions remain to be answered if these structural variations were the snapshots of dynamic organization at different time points and if they are functionally different. Live-cell imaging has provided unique insights into dynamic genome organization at short (milliseconds) and long (hours) time scales. The recent development of CRISPR-based imaging opened windows for studying dynamic chromatin organization in single cells in real time. Here we highlight these CRISPR-based imaging techniques and discuss their advances and challenges as a powerful live-cell imaging method that poses high potential to generate paradigm-shifting discoveries and reveal functional implications of dynamic chromatin organization.
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Affiliation(s)
- Jenna Thuma
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH, United States
| | - Yu-Chieh Chung
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
| | - Li-Chun Tu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, United States
- Interdisciplinary Biophysics Graduate Program, The Ohio State University, Columbus, OH, United States
- Center for RNA Biology, The Ohio State University, Columbus, OH, United States
- The Ohio State University Comprehensive Cancer Center, The Ohio State University, Columbus, OH, United States
- *Correspondence: Li-Chun Tu,
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Abstract
A chemical regularly used to image cells can dramatically alter the way cellular compartments called condensates look under the microscope.
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Affiliation(s)
- Judith Miné-Hattab
- Laboratory of Computational and Quantitative Biology, CNRS, Institut de Biologie Paris-Seine, Sorbonne UniversitéParisFrance
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