1
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Shih CP, Tang WC, Chen P, Chen BC. Applications of Lightsheet Fluorescence Microscopy by High Numerical Aperture Detection Lens. J Phys Chem B 2024; 128:8273-8289. [PMID: 39177503 DOI: 10.1021/acs.jpcb.4c01721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/24/2024]
Abstract
This Review explores the evolution, improvements, and recent applications of Light Sheet Fluorescence Microscopy (LSFM) in biological research using a high numerical aperture detection objective (lens) for imaging subcellular structures. The Review begins with an overview of the development of LSFM, tracing its evolution from its inception to its current state and emphasizing key milestones and technological advancements over the years. Subsequently, we will discuss various improvements of LSFM techniques, covering advancements in hardware such as illumination strategies, optical designs, and sample preparation methods that have enhanced imaging capabilities and resolution. The advancements in data acquisition and processing are also included, which provides a brief overview of the recent development of artificial intelligence. Fluorescence probes that were commonly used in LSFM will be highlighted, together with some insights regarding the selection of potential probe candidates for future LSFM development. Furthermore, we also discuss recent advances in the application of LSFM with a focus on high numerical aperture detection objectives for various biological studies. For sample preparation techniques, there are discussions regarding fluorescence probe selection, tissue clearing protocols, and some insights into expansion microscopy. Integrated setups such as adaptive optics, single objective modification, and microfluidics will also be some of the key discussion points in this Review. We hope that this comprehensive Review will provide a holistic perspective on the historical development, technical enhancements, and cutting-edge applications of LSFM, showcasing its pivotal role and future potential in advancing biological research.
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Affiliation(s)
- Chun-Pei Shih
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
- Department of Chemistry, National Taiwan University, Taipei 106319, Taiwan
- Nano Science and Technology Program, Taiwan International Graduate Program, Academia Sinica and National Taiwan University, Taipei 11529, Taiwan
| | - Wei-Chun Tang
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Peilin Chen
- Institute of Physics, Academia Sinica, Taipei 11529, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Bi-Chang Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
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2
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Paul MW, Aaron J, Wait E, Van Genderen R, Tyagi A, Kabbech H, Smal I, Chew TL, Kanaar R, Wyman C. Distinct mobility patterns of BRCA2 molecules at DNA damage sites. Nucleic Acids Res 2024; 52:8332-8343. [PMID: 38953170 PMCID: PMC11317164 DOI: 10.1093/nar/gkae559] [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: 12/01/2023] [Revised: 06/10/2024] [Accepted: 06/18/2024] [Indexed: 07/03/2024] Open
Abstract
BRCA2 is an essential tumor suppressor protein involved in promoting faithful repair of DNA lesions. The activity of BRCA2 needs to be tuned precisely to be active when and where it is needed. Here, we quantified the spatio-temporal dynamics of BRCA2 in living cells using aberration-corrected multifocal microscopy (acMFM). Using multicolor imaging to identify DNA damage sites, we were able to quantify its dynamic motion patterns in the nucleus and at DNA damage sites. While a large fraction of BRCA2 molecules localized near DNA damage sites appear immobile, an additional fraction of molecules exhibits subdiffusive motion, providing a potential mechanism to retain an increased number of molecules at DNA lesions. Super-resolution microscopy revealed inhomogeneous localization of BRCA2 relative to other DNA repair factors at sites of DNA damage. This suggests the presence of multiple nanoscale compartments in the chromatin surrounding the DNA lesion, which could play an important role in the contribution of BRCA2 to the regulation of the repair process.
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Affiliation(s)
- Maarten W Paul
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Jesse Aaron
- Advanced Imaging Center, HHMI Janelia, Ashburn VA, USA
| | - Eric Wait
- Advanced Imaging Center, HHMI Janelia, Ashburn VA, USA
- Elephas Biosciences, Madison WI, USA
| | - Romano M Van Genderen
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Arti Tyagi
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Bionanoscience and Kavli Institute of Nanoscience Delft, Delft, University of Technology, Delft, The Netherlands
| | - Hélène Kabbech
- Department of Cell Biology, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Ihor Smal
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Theme Biomedical Sciences, Erasmus University Medical Center, Rotterdam, The Netherlands
| | | | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
| | - Claire Wyman
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
- Department of Radiation Oncology, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, The Netherlands
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3
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Garate X, Gómez-García PA, Merino MF, Angles MC, Zhu C, Castells-García A, Ed-Daoui I, Martin L, Ochiai H, Neguembor MV, Cosma MP. The relationship between nanoscale genome organization and gene expression in mouse embryonic stem cells during pluripotency transition. Nucleic Acids Res 2024; 52:8146-8164. [PMID: 38850157 DOI: 10.1093/nar/gkae476] [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: 04/03/2023] [Revised: 05/16/2024] [Accepted: 06/05/2024] [Indexed: 06/10/2024] Open
Abstract
During early development, gene expression is tightly regulated. However, how genome organization controls gene expression during the transition from naïve embryonic stem cells to epiblast stem cells is still poorly understood. Using single-molecule microscopy approaches to reach nanoscale resolution, we show that genome remodeling affects gene transcription during pluripotency transition. Specifically, after exit from the naïve pluripotency state, chromatin becomes less compacted, and the OCT4 transcription factor has lower mobility and is more bound to its cognate sites. In epiblast cells, the active transcription hallmark, H3K9ac, decreases within the Oct4 locus, correlating with reduced accessibility of OCT4 and, in turn, with reduced expression of Oct4 nascent RNAs. Despite the high variability in the distances between active pluripotency genes, distances between Nodal and Oct4 decrease during epiblast specification. In particular, highly expressed Oct4 alleles are closer to nuclear speckles during all stages of the pluripotency transition, while only a distinct group of highly expressed Nodal alleles are in close proximity to Oct4 when associated with a nuclear speckle in epiblast cells. Overall, our results provide new insights into the role of the spatiotemporal genome remodeling during mouse pluripotency transition and its correlation with the expression of key pluripotency genes.
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Affiliation(s)
- Ximena Garate
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Pablo Aurelio Gómez-García
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Manuel Fernández Merino
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Marta Cadevall Angles
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Chenggan Zhu
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Alvaro Castells-García
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Yuexiu district, 510080 Guangzhou, China
| | - Ilyas Ed-Daoui
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Yuexiu district, 510080 Guangzhou, China
| | - Laura Martin
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Hiroshi Ochiai
- Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, 739-0046, Japan
| | - Maria Victoria Neguembor
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
| | - Maria Pia Cosma
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain
- Medical Research Institute, Guangdong Provincial People's Hospital (Guangdong Academy of Medical Sciences), Southern Medical University, 106 Zhongshan Er Road, Yuexiu district, 510080 Guangzhou, China
- ICREA, Pg. Lluis Companys 23, Barcelona 08010, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
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4
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Dong P, Zhang S, Gandin V, Xie L, Wang L, Lemire AL, Li W, Otsuna H, Kawase T, Lander AD, Chang HY, Liu ZJ. Cohesin prevents cross-domain gene coactivation. Nat Genet 2024; 56:1654-1664. [PMID: 39048795 PMCID: PMC11319207 DOI: 10.1038/s41588-024-01852-1] [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] [Received: 02/08/2023] [Accepted: 06/27/2024] [Indexed: 07/27/2024]
Abstract
The contrast between the disruption of genome topology after cohesin loss and the lack of downstream gene expression changes instigates intense debates regarding the structure-function relationship between genome and gene regulation. Here, by analyzing transcriptome and chromatin accessibility at the single-cell level, we discover that, instead of dictating population-wide gene expression levels, cohesin supplies a general function to neutralize stochastic coexpression tendencies of cis-linked genes in single cells. Notably, cohesin loss induces widespread gene coactivation and chromatin co-opening tens of million bases apart in cis. Spatial genome and protein imaging reveals that cohesin prevents gene co-bursting along the chromosome and blocks spatial mixing of transcriptional hubs. Single-molecule imaging shows that cohesin confines the exploration of diverse enhancer and core promoter binding transcriptional regulators. Together, these results support that cohesin arranges nuclear topology to control gene coexpression in single cells.
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Affiliation(s)
- Peng Dong
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
- Institute of Biomedical and Health Engineering, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China.
| | - Shu Zhang
- Center for Personal Dynamic Regulomes and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Valentina Gandin
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Liangqi Xie
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
- Cancer Biology and Infection Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Lihua Wang
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Andrew L Lemire
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Wenhong Li
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Hideo Otsuna
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Takashi Kawase
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Arthur D Lander
- Department of Developmental and Cell Biology, Center for Complex Biological Systems, University of California, Irvine, CA, USA
| | - Howard Y Chang
- Center for Personal Dynamic Regulomes and Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Zhe J Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA.
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5
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Hao S, Lee YJ, Benhamou Goldfajn N, Flores E, Liang J, Fuehrer H, Demmerle J, Lippincott-Schwartz J, Liu Z, Sukenik S, Cai D. YAP condensates are highly organized hubs. iScience 2024; 27:109927. [PMID: 38784009 PMCID: PMC11111833 DOI: 10.1016/j.isci.2024.109927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Revised: 10/24/2023] [Accepted: 05/03/2024] [Indexed: 05/25/2024] Open
Abstract
YAP/TEAD signaling is essential for organismal development, cell proliferation, and cancer progression. As a transcriptional coactivator, how YAP activates its downstream target genes is incompletely understood. YAP forms biomolecular condensates in response to hyperosmotic stress, concentrating transcription-related factors to activate downstream target genes. However, whether YAP forms condensates under other signals, how YAP condensates organize and function, and how YAP condensates activate transcription in general are unknown. Here, we report that endogenous YAP forms sub-micron scale condensates in response to Hippo pathway regulation and actin cytoskeletal tension. YAP condensates are stabilized by the transcription factor TEAD1, and recruit BRD4, a coactivator that is enriched at active enhancers. Using single-particle tracking, we found that YAP condensates slowed YAP diffusion within condensate boundaries, a possible mechanism for promoting YAP target search. These results reveal that YAP condensate formation is a highly regulated process that is critical for YAP/TEAD target gene expression.
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Affiliation(s)
- Siyuan Hao
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Ye Jin Lee
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Nadav Benhamou Goldfajn
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Department of Biophysics, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA
| | - Eduardo Flores
- Department of Chemistry and Chemical Biology, University of California, Merced, Merced, CA 95343, USA
| | - Jindayi Liang
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Hannah Fuehrer
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | - Justin Demmerle
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
| | | | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Shahar Sukenik
- Department of Chemistry and Chemical Biology, University of California, Merced, Merced, CA 95343, USA
| | - Danfeng Cai
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Department of Oncology, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
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6
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Le DJ, Hafner A, Gaddam S, Wang KC, Boettiger AN. Super-enhancer interactomes from single cells link clustering and transcription. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.08.593251. [PMID: 38766104 PMCID: PMC11100725 DOI: 10.1101/2024.05.08.593251] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Regulation of gene expression hinges on the interplay between enhancers and promoters, traditionally explored through pairwise analyses. Recent advancements in mapping genome folding, like GAM, SPRITE, and multi-contact Hi-C, have uncovered multi-way interactions among super-enhancers (SEs), spanning megabases, yet have not measured their frequency in single cells or the relationship between clustering and transcription. To close this gap, here we used multiplexed imaging to map the 3D positions of 376 SEs across thousands of mammalian nuclei. Notably, our single-cell images reveal that while SE-SE contacts are rare, SEs often form looser associations we termed "communities". These communities, averaging 4-5 SEs, assemble cooperatively under the combined effects of genomic tethers, Pol2 clustering, and nuclear compartmentalization. Larger communities are associated with more frequent and larger transcriptional bursts. Our work provides insights about the SE interactome in single cells that challenge existing hypotheses on SE clustering in the context of transcriptional regulation.
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Affiliation(s)
- Derek J. Le
- Department of Developmental Biology, Stanford University, Stanford, CA, United States
- Cancer Biology Program, Stanford University, Stanford, CA, United States
- Department of Dermatology, Stanford University, Stanford, CA, United States
- These authors contributed equally
| | - Antonina Hafner
- Department of Developmental Biology, Stanford University, Stanford, CA, United States
- These authors contributed equally
| | - Sadhana Gaddam
- Department of Dermatology, Stanford University, Stanford, CA, United States
| | - Kevin C. Wang
- Department of Dermatology, Stanford University, Stanford, CA, United States
| | - Alistair N. Boettiger
- Department of Developmental Biology, Stanford University, Stanford, CA, United States
- Lead contact
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7
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Hwang DW, Maekiniemi A, Singer RH, Sato H. Real-time single-molecule imaging of transcriptional regulatory networks in living cells. Nat Rev Genet 2024; 25:272-285. [PMID: 38195868 DOI: 10.1038/s41576-023-00684-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/27/2023] [Indexed: 01/11/2024]
Abstract
Gene regulatory networks drive the specific transcriptional programmes responsible for the diversification of cell types during the development of multicellular organisms. Although our knowledge of the genes involved in these dynamic networks has expanded rapidly, our understanding of how transcription is spatiotemporally regulated at the molecular level over a wide range of timescales in the small volume of the nucleus remains limited. Over the past few decades, advances in the field of single-molecule fluorescence imaging have enabled real-time behaviours of individual transcriptional components to be measured in living cells and organisms. These efforts are now shedding light on the dynamic mechanisms of transcription, revealing not only the temporal rules but also the spatial coordination of underlying molecular interactions during various biological events.
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Affiliation(s)
- Dong-Woo Hwang
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Anna Maekiniemi
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Robert H Singer
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA
| | - Hanae Sato
- Department of Cell Biology, Albert Einstein College of Medicine, New York, NY, USA.
- Nano Life Science Institute (WPI-Nano LSI), Kanazawa University, Kakuma-machi, Kanazawa, Japan.
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8
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Shi Y, Tabet JS, Milkie DE, Daugird TA, Yang CQ, Ritter AT, Giovannucci A, Legant WR. Smart lattice light-sheet microscopy for imaging rare and complex cellular events. Nat Methods 2024; 21:301-310. [PMID: 38167656 PMCID: PMC11216155 DOI: 10.1038/s41592-023-02126-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2023] [Accepted: 11/09/2023] [Indexed: 01/05/2024]
Abstract
Light-sheet microscopes enable rapid high-resolution imaging of biological specimens; however, biological processes span spatiotemporal scales. Moreover, long-term phenotypes are often instigated by rare or fleeting biological events that are difficult to capture with a single imaging modality. Here, to overcome this limitation, we present smartLLSM, a microscope that incorporates artificial intelligence-based instrument control to autonomously switch between epifluorescent inverted imaging and lattice light-sheet microscopy (LLSM). We apply this approach to two unique processes: cell division and immune synapse formation. In each context, smartLLSM provides population-level statistics across thousands of cells and autonomously captures multicolor three-dimensional datasets or four-dimensional time-lapse movies of rare events at rates that dramatically exceed human capabilities. From this, we quantify the effects of Taxol dose on spindle structure and kinetochore dynamics in dividing cells and of antigen strength on cytotoxic T lymphocyte engagement and lytic granule polarization at the immune synapse. Overall, smartLLSM efficiently detects rare events within heterogeneous cell populations and records these processes with high spatiotemporal four-dimensional imaging over statistically significant replicates.
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Affiliation(s)
- Yu Shi
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Jimmy S Tabet
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Daniel E Milkie
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA, USA
| | - Timothy A Daugird
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Chelsea Q Yang
- Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | | | - Andrea Giovannucci
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
| | - Wesley R Legant
- Joint Department of Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
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9
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Hannon CE, Eisen MB. Intrinsic protein disorder is insufficient to drive subnuclear clustering in embryonic transcription factors. eLife 2024; 12:RP88221. [PMID: 38275292 PMCID: PMC10945700 DOI: 10.7554/elife.88221] [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: 01/27/2024] Open
Abstract
Modern microscopy has revealed that core nuclear functions, including transcription, replication, and heterochromatin formation, occur in spatially restricted clusters. Previous work from our lab has shown that subnuclear high-concentration clusters of transcription factors may play a role in regulating RNA synthesis in the early Drosophila embryo. A nearly ubiquitous feature of eukaryotic transcription factors is that they contain intrinsically disordered regions (IDRs) that often arise from low complexity amino acid sequences within the protein. It has been proposed that IDRs within transcription factors drive co-localization of transcriptional machinery and target genes into high-concentration clusters within nuclei. Here, we test that hypothesis directly, by conducting a broad survey of the subnuclear localization of IDRs derived from transcription factors. Using a novel algorithm to identify IDRs in the Drosophila proteome, we generated a library of IDRs from transcription factors expressed in the early Drosophila embryo. We used this library to perform a high-throughput imaging screen in Drosophila Schneider-2 (S2) cells. We found that while subnuclear clustering does not occur when the majority of IDRs are expressed alone, it is frequently seen in full-length transcription factors. These results are consistent in live Drosophila embryos, suggesting that IDRs are insufficient to drive the subnuclear clustering behavior of transcription factors. Furthermore, the clustering of transcription factors in living embryos was unaffected by the deletion of IDR sequences. Our results demonstrate that IDRs are unlikely to be the primary molecular drivers of the clustering observed during transcription, suggesting a more complex and nuanced role for these disordered protein sequences.
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Affiliation(s)
- Colleen E Hannon
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
| | - Michael B Eisen
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
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10
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Atsumi Y, Iwata R, Kimura H, Vanderhaeghen P, Yamamoto N, Sugo N. Repetitive CREB-DNA interactions at gene loci predetermined by CBP induce activity-dependent gene expression in human cortical neurons. Cell Rep 2024; 43:113576. [PMID: 38128530 DOI: 10.1016/j.celrep.2023.113576] [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: 05/23/2023] [Revised: 11/10/2023] [Accepted: 11/27/2023] [Indexed: 12/23/2023] Open
Abstract
Neuronal activity-dependent transcription plays a key role in plasticity and pathology in the brain. An intriguing question is how neuronal activity controls gene expression via interactions of transcription factors with DNA and chromatin modifiers in the nucleus. By utilizing single-molecule imaging in human embryonic stem cell (ESC)-derived cortical neurons, we demonstrate that neuronal activity increases repetitive emergence of cAMP response element-binding protein (CREB) at histone acetylation sites in the nucleus, where RNA polymerase II (RNAPII) accumulation and FOS expression occur rapidly. Neuronal activity also enhances co-localization of CREB and CREB-binding protein (CBP). Increased binding of a constitutively active CREB to CBP efficiently induces CREB repetitive emergence. On the other hand, the formation of histone acetylation sites is dependent on CBP histone modification via acetyltransferase (HAT) activity but is not affected by neuronal activity. Taken together, our results suggest that neuronal activity promotes repetitive CREB-CRE and CREB-CBP interactions at predetermined histone acetylation sites, leading to rapid gene expression.
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Affiliation(s)
- Yuri Atsumi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ryohei Iwata
- VIB-KU Leuven, Center for Brain & Disease Research and KU Leuven, Department of Neurosciences & Leuven Brain Institute, 3000 Leuven, Belgium
| | - Hiroshi Kimura
- Cell Biology Center, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Kanagawa 226-8503, Japan
| | - Pierre Vanderhaeghen
- VIB-KU Leuven, Center for Brain & Disease Research and KU Leuven, Department of Neurosciences & Leuven Brain Institute, 3000 Leuven, Belgium
| | - Nobuhiko Yamamoto
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan; Institute of Neurological and Psychiatric Disorders, Shenzhen Bay Laboratory, Shenzhen, Guangdong 518132, China.
| | - Noriyuki Sugo
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka 565-0871, Japan.
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11
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Kondoh H. Enhancer Activation by Transcription Factors and Underlying Mechanisms. Results Probl Cell Differ 2024; 72:167-191. [PMID: 38509258 DOI: 10.1007/978-3-031-39027-2_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Enhancers are classified into two classes based on various criteria. Class I enhancers participate primarily in finely tuned cell-specific regulation, as exemplified by the neural enhancers discussed in Chap. 9 . They are activated by simultaneous binding of transcription factors (TFs) to adjacent sites in the core sequence and are marked by moderate levels of H3K27ac modification. Class II enhancers are activated by the reiterated binding of the same TFs at multiple sites and are marked by high levels of H3K27ac modification. Class II enhancers are exemplified by enhancers in the SCR downstream of the Sox2 gene, as also discussed in Chap. 9 . Both classes of enhancers activate transcription similarly with low selectivity toward the promoters.The genomic loci broadly covered by high-level H3K27ac modification were once dubbed "Super-enhancers," implying that they are densely packed enhancers with superpowers in gene regulation. However, marking with H3K27ac modification does not predict the enhancer activity of a sequence; a "Super enhancer" region includes a few ordinary Class II enhancers. Currently, the most reliable criterion for enhancer prediction is cross-species sequence conservation.The mechanism by which transcription factors find and stay on the target enhancer site remains elusive. Results from two approaches, single-molecule live imaging and kinetic analysis using FRAP, are discussed.
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Affiliation(s)
- Hisato Kondoh
- Osaka University, Suita, Osaka, Japan
- Biohistory Research Hall, Takatsuki, Osaka, Japan
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12
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Heemskerk T, van de Kamp G, Essers J, Kanaar R, Paul MW. Multi-scale cellular imaging of DNA double strand break repair. DNA Repair (Amst) 2023; 131:103570. [PMID: 37734176 DOI: 10.1016/j.dnarep.2023.103570] [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: 04/30/2023] [Revised: 09/08/2023] [Accepted: 09/11/2023] [Indexed: 09/23/2023]
Abstract
Live-cell and high-resolution fluorescence microscopy are powerful tools to study the organization and dynamics of DNA double-strand break repair foci and specific repair proteins in single cells. This requires specific induction of DNA double-strand breaks and fluorescent markers to follow the DNA lesions in living cells. In this review, where we focused on mammalian cell studies, we discuss different methods to induce DNA double-strand breaks, how to visualize and quantify repair foci in living cells., We describe different (live-cell) imaging modalities that can reveal details of the DNA double-strand break repair process across multiple time and spatial scales. In addition, recent developments are discussed in super-resolution imaging and single-molecule tracking, and how these technologies can be applied to elucidate details on structural compositions or dynamics of DNA double-strand break repair.
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Affiliation(s)
- Tim Heemskerk
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Gerarda van de Kamp
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Jeroen Essers
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Vascular Surgery, Erasmus University Medical Center, Rotterdam, the Netherlands; Department of Radiotherapy, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Roland Kanaar
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands
| | - Maarten W Paul
- Department of Molecular Genetics, Oncode Institute, Erasmus MC Cancer Institute, Erasmus University Medical Center, Rotterdam, the Netherlands.
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13
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Abstract
Cells must tightly regulate their gene expression programs and yet rapidly respond to acute biochemical and biophysical cues within their environment. This information is transmitted to the nucleus through various signaling cascades, culminating in the activation or repression of target genes. Transcription factors (TFs) are key mediators of these signals, binding to specific regulatory elements within chromatin. While live-cell imaging has conclusively proven that TF-chromatin interactions are highly dynamic, how such transient interactions can have long-term impacts on developmental trajectories and disease progression is still largely unclear. In this review, we summarize our current understanding of the dynamic nature of TF functions, starting with a historical overview of early live-cell experiments. We highlight key factors that govern TF dynamics and how TF dynamics, in turn, affect downstream transcriptional bursting. Finally, we conclude with open challenges and emerging technologies that will further our understanding of transcriptional regulation.
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Affiliation(s)
- Kaustubh Wagh
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA; , ,
- Department of Physics, University of Maryland, College Park, Maryland, USA;
| | - Diana A Stavreva
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA; , ,
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, Maryland, USA;
- Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA; , ,
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14
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Strawbridge SE, Kurowski A, Corujo-Simon E, Fletcher AN, Nichols J, Fletcher AG. insideOutside: an accessible algorithm for classifying interior and exterior points, with applications in embryology. Biol Open 2023; 12:bio060055. [PMID: 37623821 PMCID: PMC10461464 DOI: 10.1242/bio.060055] [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: 07/26/2023] [Accepted: 07/27/2023] [Indexed: 08/26/2023] Open
Abstract
A crucial aspect of embryology is relating the position of individual cells to the broader geometry of the embryo. A classic example of this is the first cell-fate decision of the mouse embryo, where interior cells become inner cell mass and exterior cells become trophectoderm. Fluorescent labelling, imaging, and quantification of tissue-specific proteins have advanced our understanding of this dynamic process. However, instances arise where these markers are either not available, or not reliable, and we are left only with the cells' spatial locations. Therefore, a simple, robust method for classifying interior and exterior cells of an embryo using spatial information is required. Here, we describe a simple mathematical framework and an unsupervised machine learning approach, termed insideOutside, for classifying interior and exterior points of a three-dimensional point-cloud, a common output from imaged cells within the early mouse embryo. We benchmark our method against other published methods to demonstrate that it yields greater accuracy in classification of nuclei from the pre-implantation mouse embryos and greater accuracy when challenged with local surface concavities. We have made MATLAB and Python implementations of the method freely available. This method should prove useful for embryology, with broader applications to similar data arising in the life sciences.
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Affiliation(s)
- Stanley E. Strawbridge
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Physiology, Neuroscience and Development, University of Cambridge, Cambridge, UK
| | - Agata Kurowski
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Elena Corujo-Simon
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Physiology, Neuroscience and Development, University of Cambridge, Cambridge, UK
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh, UK
| | - Alastair N. Fletcher
- Department of Mathematical Sciences, Northern Illinois University, DeKalb, IL, USA
| | - Jennifer Nichols
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
- Department of Physiology, Neuroscience and Development, University of Cambridge, Cambridge, UK
- MRC Human Genetics Unit, University of Edinburgh, Edinburgh, UK
- Centre for Trophoblast Research, University of Cambridge, Cambridge, UK
| | - Alexander G. Fletcher
- School of Mathematics and Statistics, University of Sheffield, Sheffield, UK
- The Bateson Centre, University of Sheffield, Sheffield, UK
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15
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Heyza JR, Mikhova M, Schmidt JC. Live cell single-molecule imaging to study DNA repair in human cells. DNA Repair (Amst) 2023; 129:103540. [PMID: 37467632 PMCID: PMC10530516 DOI: 10.1016/j.dnarep.2023.103540] [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: 03/31/2023] [Revised: 06/29/2023] [Accepted: 07/05/2023] [Indexed: 07/21/2023]
Abstract
The genetic material in human cells is continuously exposed to a wide variety of insults that can induce different DNA lesions. To maintain genomic stability and prevent potentially deleterious genetic changes caused by DNA damage, mammalian cells have evolved a number of pathways that repair specific types of DNA damage. These DNA repair pathways vary in their accuracy, some providing high-fidelity repair while others are error-prone and are only activated as a last resort. Adding additional complexity to cellular mechanisms of DNA repair is the DNA damage response which is a sophisticated a signaling network that coordinates repair outcomes, cell-cycle checkpoint activation, and cell fate decisions. As a result of the sheer complexity of the various DNA repair pathways and the DNA damage response there are large gaps in our understanding of the molecular mechanisms underlying DNA damage repair in human cells. A key unaddressed question is how the dynamic recruitment of DNA repair factors contributes to repair kinetics and repair pathway choice in human cells. Methodological advances in live cell single-molecule imaging over the last decade now allow researchers to directly observe and analyze the dynamics of DNA repair proteins in living cells with high spatiotemporal resolution. Live cell single-molecule imaging combined with single-particle tracking can provide direct insight into the biochemical reactions that control DNA repair and has the power to identify previously unobservable processes in living cells. This review summarizes the main considerations for experimental design and execution for live cell single-molecule imaging experiments and describes how they can be used to define the molecular mechanisms of DNA damage repair in mammalian cells.
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Affiliation(s)
- Joshua R Heyza
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA
| | - Mariia Mikhova
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA; Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA
| | - Jens C Schmidt
- Institute for Quantitative Health Science and Engineering, Michigan State University, East Lansing, MI, USA; Department of Obstetrics, Gynecology, and Reproductive Biology, Michigan State University, East Lansing, MI, USA.
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16
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Hamilton DJ, Hein AE, Wuttke DS, Batey RT. The DNA binding high mobility group box protein family functionally binds RNA. WILEY INTERDISCIPLINARY REVIEWS. RNA 2023; 14:e1778. [PMID: 36646476 PMCID: PMC10349909 DOI: 10.1002/wrna.1778] [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: 10/26/2022] [Revised: 12/22/2022] [Accepted: 12/27/2022] [Indexed: 01/18/2023]
Abstract
Nucleic acid binding proteins regulate transcription, splicing, RNA stability, RNA localization, and translation, together tailoring gene expression in response to stimuli. Upon discovery, these proteins are typically classified as either DNA or RNA binding as defined by their in vivo functions; however, recent evidence suggests dual DNA and RNA binding by many of these proteins. High mobility group box (HMGB) proteins have a DNA binding HMGB domain, act as transcription factors and chromatin remodeling proteins, and are increasingly understood to interact with RNA as means to regulate gene expression. Herein, multiple layers of evidence that the HMGB family are dual DNA and RNA binding proteins is comprehensively reviewed. For example, HMGB proteins directly interact with RNA in vitro and in vivo, are localized to RNP granules involved in RNA processing, and their protein interactors are enriched in RNA binding proteins involved in RNA metabolism. Importantly, in cell-based systems, HMGB-RNA interactions facilitate protein-protein interactions, impact splicing outcomes, and modify HMGB protein genomic or cellular localization. Misregulation of these HMGB-RNA interactions are also likely involved in human disease. This review brings to light that as a family, HMGB proteins are likely to bind RNA which is essential to HMGB protein biology. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Protein-RNA Recognition RNA Interactions with Proteins and Other Molecules > RNA-Protein Complexes RNA Interactions with Proteins and Other Molecules > Protein-RNA Interactions: Functional Implications.
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17
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Weng M, Hu H, Graus MS, Tan DS, Gao Y, Ren S, Ho DHH, Langer J, Holzner M, Huang Y, Ling GS, Lai CSW, Francois M, Jauch R. An engineered Sox17 induces somatic to neural stem cell fate transitions independently from pluripotency reprogramming. SCIENCE ADVANCES 2023; 9:eadh2501. [PMID: 37611093 PMCID: PMC10446497 DOI: 10.1126/sciadv.adh2501] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 07/21/2023] [Indexed: 08/25/2023]
Abstract
Advanced strategies to interconvert cell types provide promising avenues to model cellular pathologies and to develop therapies for neurological disorders. Yet, methods to directly transdifferentiate somatic cells into multipotent induced neural stem cells (iNSCs) are slow and inefficient, and it is unclear whether cells pass through a pluripotent state with full epigenetic reset. We report iNSC reprogramming from embryonic and aged mouse fibroblasts as well as from human blood using an engineered Sox17 (eSox17FNV). eSox17FNV efficiently drives iNSC reprogramming while Sox2 or Sox17 fail. eSox17FNV acquires the capacity to bind different protein partners on regulatory DNA to scan the genome more efficiently and has a more potent transactivation domain than Sox2. Lineage tracing and time-resolved transcriptomics show that emerging iNSCs do not transit through a pluripotent state. Our work distinguishes lineage from pluripotency reprogramming with the potential to generate more authentic cell models for aging-associated neurodegenerative diseases.
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Affiliation(s)
- Mingxi Weng
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Center for Translational Stem Cell Biology, Hong Kong SAR, China
| | - Haoqing Hu
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Matthew S. Graus
- The David Richmond Laboratory for Cardiovascular Development: Gene Regulation and Editing Program, The Centenary Institute, Camperdown, NSW 2006, Australia
- Genome Imaging Centre, The Centenary Institute, Camperdown, NSW 2006, Australia
| | - Daisylyn Senna Tan
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Ya Gao
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Shimiao Ren
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Derek Hoi Hang Ho
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Center for Translational Stem Cell Biology, Hong Kong SAR, China
| | - Jakob Langer
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Markus Holzner
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Yuhua Huang
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Guang Sheng Ling
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Cora Sau Wan Lai
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- State Key Laboratory of Cognitive and Brain Research, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
| | - Mathias Francois
- The David Richmond Laboratory for Cardiovascular Development: Gene Regulation and Editing Program, The Centenary Institute, Camperdown, NSW 2006, Australia
- Genome Imaging Centre, The Centenary Institute, Camperdown, NSW 2006, Australia
- The University of Sydney, School of Medical Sciences, Camperdown, NSW 2006, Australia
| | - Ralf Jauch
- School of Biomedical Sciences, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China
- Center for Translational Stem Cell Biology, Hong Kong SAR, China
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18
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Basumatary J, Baro N, Zanacchi FC, Mondal PP. Temporally resolved SMLM (with large PAR shift) enabled visualization of dynamic HA cluster formation and migration in a live cell. Sci Rep 2023; 13:12561. [PMID: 37532749 PMCID: PMC10397235 DOI: 10.1038/s41598-023-39096-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Accepted: 07/20/2023] [Indexed: 08/04/2023] Open
Abstract
The blinking properties of a single molecule are critical for single-molecule localization microscopy (SMLM). Typically, SMLM techniques involve recording several frames of diffraction-limited bright spots of single-molecules with a detector exposure time close to the blinking period. This sets a limit on the temporal resolution of SMLM to a few tens of milliseconds. Realizing that a substantial fraction of single molecules emit photons for time scales much shorter than the average blinking period, we propose accelerating data collection to capture these fast emitters. Here, we put forward a short exposure-based SMLM (shortSMLM) method powered by sCMOS detector for understanding dynamical events (both at single molecule and ensemble level). The technique is demonstrated on an Influenza-A disease model, where NIH3T3 cells (both fixed and live cells) were transfected by Dendra2-HA plasmid DNA. Analysis shows a 2.76-fold improvement in the temporal resolution that comes with a sacrifice in spatial resolution, and a particle resolution shift PAR-shift (in terms of localization precision) of [Formula: see text] 11.82 nm compared to standard SMLM. We visualized dynamic HA cluster formation in transfected cells post 24 h of DNA transfection. It is noted that a reduction in spatial resolution does not substantially alter cluster characteristics (cluster density, [Formula: see text] molecules/cluster, cluster spread, etc.) and, indeed, preserves critical features. Moreover, the time-lapse imaging reveals the dynamic formation and migration of Hemagglutinin (HA) clusters in a live cell. This suggests that [Formula: see text] using a synchronized high QE sCMOS detector (operated at short exposure times) is excellent for studying temporal dynamics in cellular system.
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Affiliation(s)
- Jigmi Basumatary
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India
| | - Neptune Baro
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India
| | | | - Partha Pratim Mondal
- Instrumentation and Applied Physics, Indian Institute of Science, Bangalore, India.
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19
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Theis A, Harrison MM. Reprogramming of three-dimensional chromatin organization in the early embryo. Curr Opin Struct Biol 2023; 81:102613. [PMID: 37224641 PMCID: PMC10524315 DOI: 10.1016/j.sbi.2023.102613] [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: 03/21/2023] [Revised: 04/24/2023] [Accepted: 04/26/2023] [Indexed: 05/26/2023]
Abstract
Chromatin organization within the three-dimensional (3D) nuclear space is important for proper gene expression and developmental programming. This organization is established during the dramatic reprogramming that occurs in early embryonic development. Thus, the early embryo is an ideal model for examining the formation and dynamics of 3D chromatin structure. Advances in high-resolution microscopy and single-nucleus genomic analyses have provided fundamental insights into the mechanisms driving genome organization in the early embryo. Here, we highlight recent findings describing the dynamics and driving mechanisms for establishing 3D chromatin organization and discuss the role such organization has on gene regulation in early embryonic development.
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Affiliation(s)
- Alexandra Theis
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
| | - Melissa M Harrison
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI, USA.
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20
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Schnermann MJ, Lavis LD. Rejuvenating old fluorophores with new chemistry. Curr Opin Chem Biol 2023; 75:102335. [PMID: 37269674 PMCID: PMC10524207 DOI: 10.1016/j.cbpa.2023.102335] [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: 01/31/2023] [Revised: 04/26/2023] [Accepted: 05/02/2023] [Indexed: 06/05/2023]
Abstract
The field of organic chemistry began with 19th century scientists identifying and then expanding upon synthetic dye molecules for textiles. In the 20th century, dye chemistry continued with the aim of developing photographic sensitizers and laser dyes. Now, in the 21st century, the rapid evolution of biological imaging techniques provides a new driving force for dye chemistry. Of the extant collection of synthetic fluorescent dyes for biological imaging, two classes reign supreme: rhodamines and cyanines. Here, we provide an overview of recent examples where modern chemistry is used to build these old-but-venerable classes of optically responsive molecules. These new synthetic methods access new fluorophores, which then enable sophisticated imaging experiments leading to new biological insights.
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Affiliation(s)
- Martin J Schnermann
- Chemical Biology Laboratory, Center for Cancer Research, National Cancer Institute, Building 376, Frederick, MD 20850, USA.
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA, 20147, USA.
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21
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Lerner J, Katznelson A, Zhang J, Zaret KS. Different chromatin-scanning modes lead to targeting of compacted chromatin by pioneer factors FOXA1 and SOX2. Cell Rep 2023; 42:112748. [PMID: 37405916 PMCID: PMC10529229 DOI: 10.1016/j.celrep.2023.112748] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Revised: 04/20/2023] [Accepted: 06/19/2023] [Indexed: 07/07/2023] Open
Abstract
Pioneer transcription factors interact with nucleosomes to scan silent, compact chromatin, enabling cooperative events that modulate gene activity. While at a subset of sites pioneer factors access chromatin by assisted loading with other transcription factors, the nucleosome-binding properties of pioneer factors enable them to initiate zygotic genome activation, embryonic development, and cellular reprogramming. To better understand nucleosome targeting in vivo, we assess whether pioneer factors FoxA1 and Sox2 target stable or unstable nucleosomes and find that they target DNase-resistant, stable nucleosomes, whereas HNF4A, a non-nucleosome binding factor, targets open, DNase-sensitive chromatin. Despite FOXA1 and SOX2 targeting similar proportions of DNase-resistant chromatin, using single-molecule tracking, we find that FOXA1 uses lower nucleoplasmic diffusion and longer residence times while SOX2 uses higher nucleoplasmic diffusion and shorter residence times to scan compact chromatin, while HNF4 scans compact chromatin much less efficiently. Thus, pioneer factors target compact chromatin through distinct processes.
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Affiliation(s)
- Jonathan Lerner
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Andrew Katznelson
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Jingchao Zhang
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Kenneth S Zaret
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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22
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Meeussen JVW, Pomp W, Brouwer I, de Jonge WJ, Patel HP, Lenstra TL. Transcription factor clusters enable target search but do not contribute to target gene activation. Nucleic Acids Res 2023; 51:5449-5468. [PMID: 36987884 PMCID: PMC10287935 DOI: 10.1093/nar/gkad227] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 03/06/2023] [Accepted: 03/16/2023] [Indexed: 03/30/2023] Open
Abstract
Many transcription factors (TFs) localize in nuclear clusters of locally increased concentrations, but how TF clustering is regulated and how it influences gene expression is not well understood. Here, we use quantitative microscopy in living cells to study the regulation and function of clustering of the budding yeast TF Gal4 in its endogenous context. Our results show that Gal4 forms clusters that overlap with the GAL loci. Cluster number, density and size are regulated in different growth conditions by the Gal4-inhibitor Gal80 and Gal4 concentration. Gal4 truncation mutants reveal that Gal4 clustering is facilitated by, but does not completely depend on DNA binding and intrinsically disordered regions. Moreover, we discover that clustering acts as a double-edged sword: self-interactions aid TF recruitment to target genes, but recruited Gal4 molecules that are not DNA-bound do not contribute to, and may even inhibit, transcription activation. We propose that cells need to balance the different effects of TF clustering on target search and transcription activation to facilitate proper gene expression.
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Affiliation(s)
- Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Wim Pomp
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Ineke Brouwer
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Wim J de Jonge
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Heta P Patel
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, The Netherlands
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23
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van Staalduinen J, van Staveren T, Grosveld F, Wendt KS. Live-cell imaging of chromatin contacts opens a new window into chromatin dynamics. Epigenetics Chromatin 2023; 16:27. [PMID: 37349773 PMCID: PMC10288748 DOI: 10.1186/s13072-023-00503-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Accepted: 06/15/2023] [Indexed: 06/24/2023] Open
Abstract
Our understanding of the organization of the chromatin fiber within the cell nucleus has made great progress in the last few years. High-resolution techniques based on next-generation sequencing as well as optical imaging that can investigate chromatin conformations down to the single cell level have revealed that chromatin structure is highly heterogeneous at the level of the individual allele. While TAD boundaries and enhancer-promoter pairs emerge as hotspots of 3D proximity, the spatiotemporal dynamics of these different types of chromatin contacts remain largely unexplored. Investigation of chromatin contacts in live single cells is necessary to close this knowledge gap and further enhance the current models of 3D genome organization and enhancer-promoter communication. In this review, we first discuss the potential of single locus labeling to study architectural and enhancer-promoter contacts and provide an overview of the available single locus labeling techniques such as FROS, TALE, CRISPR-dCas9 and ANCHOR, and discuss the latest developments and applications of these systems.
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Affiliation(s)
- Jente van Staalduinen
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Thomas van Staveren
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Frank Grosveld
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands
| | - Kerstin S Wendt
- Department of Cell Biology, Erasmus MC, Dr. Molewaterplein 50, 3015 GE, Rotterdam, The Netherlands.
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24
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Beagrie RA, Thieme CJ, Annunziatella C, Baugher C, Zhang Y, Schueler M, Kukalev A, Kempfer R, Chiariello AM, Bianco S, Li Y, Davis T, Scialdone A, Welch LR, Nicodemi M, Pombo A. Multiplex-GAM: genome-wide identification of chromatin contacts yields insights overlooked by Hi-C. Nat Methods 2023:10.1038/s41592-023-01903-1. [PMID: 37336949 PMCID: PMC10333126 DOI: 10.1038/s41592-023-01903-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 05/01/2023] [Indexed: 06/21/2023]
Abstract
Technology for measuring 3D genome topology is increasingly important for studying gene regulation, for genome assembly and for mapping of genome rearrangements. Hi-C and other ligation-based methods have become routine but have specific biases. Here, we develop multiplex-GAM, a faster and more affordable version of genome architecture mapping (GAM), a ligation-free technique that maps chromatin contacts genome-wide. We perform a detailed comparison of multiplex-GAM and Hi-C using mouse embryonic stem cells. When examining the strongest contacts detected by either method, we find that only one-third of these are shared. The strongest contacts specifically found in GAM often involve 'active' regions, including many transcribed genes and super-enhancers, whereas in Hi-C they more often contain 'inactive' regions. Our work shows that active genomic regions are involved in extensive complex contacts that are currently underestimated in ligation-based approaches, and highlights the need for orthogonal advances in genome-wide contact mapping technologies.
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Affiliation(s)
- Robert A Beagrie
- 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
- Laboratory of Gene Regulation, Weatherall Institute of Molecular Medicine, Oxford, UK
- Chromatin and Disease Group, Wellcome Centre for Human Genetics, Oxford, UK
| | - Christoph J Thieme
- 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
| | - Carlo Annunziatella
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Catherine Baugher
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Yingnan Zhang
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Markus Schueler
- 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
| | - Alexander Kukalev
- 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
| | - Rieke Kempfer
- 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, Berlin, Germany
| | - Andrea M Chiariello
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Simona Bianco
- 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
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Naples, Italy
| | - Yichao Li
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Trenton Davis
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA
| | - Antonio Scialdone
- Institute of Epigenetics and Stem Cells, Helmholtz Zentrum München - German Research Center for Environmental Health, Munich, Germany
- Institute of Functional Epigenetics, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Computational Biology, Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany
| | - Lonnie R Welch
- School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA.
| | - Mario Nicodemi
- 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.
- Dipartimento di Fisica, Università di Napoli Federico II, and INFN Napoli, CNR-SPIN, Complesso Universitario di Monte Sant'Angelo, Naples, Italy.
- Berlin Institute of Health (BIH), MDC-Berlin, Berlin, Germany.
| | - 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, Berlin, Germany.
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25
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Nguyen TD, Chen YI, Chen LH, Yeh HC. Recent Advances in Single-Molecule Tracking and Imaging Techniques. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2023; 16:253-284. [PMID: 37314878 DOI: 10.1146/annurev-anchem-091922-073057] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Since the early 1990s, single-molecule detection in solution at room temperature has enabled direct observation of single biomolecules at work in real time and under physiological conditions, providing insights into complex biological systems that the traditional ensemble methods cannot offer. In particular, recent advances in single-molecule tracking techniques allow researchers to follow individual biomolecules in their native environments for a timescale of seconds to minutes, revealing not only the distinct pathways these biomolecules take for downstream signaling but also their roles in supporting life. In this review, we discuss various single-molecule tracking and imaging techniques developed to date, with an emphasis on advanced three-dimensional (3D) tracking systems that not only achieve ultrahigh spatiotemporal resolution but also provide sufficient working depths suitable for tracking single molecules in 3D tissue models. We then summarize the observables that can be extracted from the trajectory data. Methods to perform single-molecule clustering analysis and future directions are also discussed.
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Affiliation(s)
- Trung Duc Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Yuan-I Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Limin H Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
- Texas Materials Institute, University of Texas at Austin, Austin, Texas, USA
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26
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Reani Y, Bobrowski O. Cycle Registration in Persistent Homology With Applications in Topological Bootstrap. IEEE TRANSACTIONS ON PATTERN ANALYSIS AND MACHINE INTELLIGENCE 2023; 45:5579-5593. [PMID: 36301785 DOI: 10.1109/tpami.2022.3217443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We propose a novel approach for comparing the persistent homology representations of two spaces (or filtrations). Commonly used methods are based on numerical summaries such as persistence diagrams and persistence landscapes, along with suitable metrics (e.g., Wasserstein). These summaries are useful for computational purposes, but they are merely a marginal of the actual topological information that persistent homology can provide. Instead, our approach compares between two topological representations directly in the data space. We do so by defining a correspondence relation between individual persistent cycles of two different spaces, and devising a method for computing this correspondence. Our matching of cycles is based on both the persistence intervals and the spatial placement of each feature. We demonstrate our new framework in the context of topological inference, where we use statistical bootstrap methods in order to differentiate between real features and noise in point cloud data.
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27
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Shi Y, Tabet JS, Milkie DE, Daugird TA, Yang CQ, Giovannucci A, Legant WR. Smart Lattice Light Sheet Microscopy for imaging rare and complex cellular events. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.07.531517. [PMID: 36945393 PMCID: PMC10028917 DOI: 10.1101/2023.03.07.531517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
Light sheet microscopes enable rapid, high-resolution imaging of biological specimens; however, biological processes span a variety of spatiotemporal scales. Moreover, long-term phenotypes are often instigated by rare or fleeting biological events that are difficult to capture with a single imaging modality and constant imaging parameters. To overcome this limitation, we present smartLLSM, a microscope that incorporates AI-based instrument control to autonomously switch between epifluorescent inverted imaging and lattice light sheet microscopy. We apply this technology to two major scenarios. First, we demonstrate that the instrument provides population-level statistics of cell cycle states across thousands of cells on a coverslip. Second, we show that by using real-time image feedback to switch between imaging modes, the instrument autonomously captures multicolor 3D datasets or 4D time-lapse movies of dividing cells at rates that dramatically exceed human capabilities. Quantitative image analysis on high-content + high-throughput datasets reveal kinetochore and chromosome dynamics in dividing cells and determine the effects of drug perturbation on cells in specific mitotic stages. This new methodology enables efficient detection of rare events within a heterogeneous cell population and records these processes with high spatiotemporal 4D imaging over statistically significant replicates.
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28
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Ball DA, Jalloh B, Karpova TS. Impact of Saccharomyces cerevisiae on the Field of Single-Molecule Biophysics. Int J Mol Sci 2022; 23:ijms232415895. [PMID: 36555532 PMCID: PMC9781480 DOI: 10.3390/ijms232415895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/10/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022] Open
Abstract
Cellular functions depend on the dynamic assembly of protein regulator complexes at specific cellular locations. Single Molecule Tracking (SMT) is a method of choice for the biochemical characterization of protein dynamics in vitro and in vivo. SMT follows individual molecules in live cells and provides direct information about their behavior. SMT was successfully applied to mammalian models. However, mammalian cells provide a complex environment where protein mobility depends on numerous factors that are difficult to control experimentally. Therefore, yeast cells, which are unicellular and well-studied with a small and completely sequenced genome, provide an attractive alternative for SMT. The simplicity of organization, ease of genetic manipulation, and tolerance to gene fusions all make yeast a great model for quantifying the kinetics of major enzymes, membrane proteins, and nuclear and cellular bodies. However, very few researchers apply SMT techniques to yeast. Our goal is to promote SMT in yeast to a wider research community. Our review serves a dual purpose. We explain how SMT is conducted in yeast cells, and we discuss the latest insights from yeast SMT while putting them in perspective with SMT of higher eukaryotes.
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29
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Malivert M, Harms F, Veilly C, Legrand J, Li Z, Bayer E, Choquet D, Ducros M. Active image optimization for lattice light sheet microscopy in thick samples. BIOMEDICAL OPTICS EXPRESS 2022; 13:6211-6228. [PMID: 36589592 PMCID: PMC9774867 DOI: 10.1364/boe.471757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/09/2022] [Accepted: 09/14/2022] [Indexed: 05/02/2023]
Abstract
Lattice light-sheet microscopy (LLSM) is a very efficient technique for high resolution 3D imaging of dynamic phenomena in living biological samples. However, LLSM imaging remains limited in depth due to optical aberrations caused by sample-based refractive index mismatch. Here, we propose a simple and low-cost active image optimization (AIO) method to recover high resolution imaging inside thick biological samples. AIO is based on (1) a light-sheet autofocus step (AF) followed by (2) an adaptive optics image-based optimization. We determine the optimum AIO parameters to provide a fast, precise and robust aberration correction on biological samples. Finally, we demonstrate the performances of our approach on sub-micrometric structures in brain slices and plant roots.
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Affiliation(s)
- Maxime Malivert
- Université de Bordeaux, CNRS, INSERM, Bordeaux Imaging Center (BIC), UAR 3420, US 4, F-33000 Bordeaux, France
- Imagine Optic, F-91400 Orsay, France
| | | | | | | | - Ziqiang Li
- Université de Bordeaux, CNRS, Laboratory of Membrane Biogenesis (LBM), UMR 5200, F-33140 Villenave d’Ornon, France
| | - Emmanuelle Bayer
- Université de Bordeaux, CNRS, Laboratory of Membrane Biogenesis (LBM), UMR 5200, F-33140 Villenave d’Ornon, France
| | - Daniel Choquet
- Université de Bordeaux, CNRS, INSERM, Bordeaux Imaging Center (BIC), UAR 3420, US 4, F-33000 Bordeaux, France
- Université de Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience (IINS), UMR 5297, F-33000 Bordeaux, France
| | - Mathieu Ducros
- Université de Bordeaux, CNRS, INSERM, Bordeaux Imaging Center (BIC), UAR 3420, US 4, F-33000 Bordeaux, France
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30
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Regulation associated modules reflect 3D genome modularity associated with chromatin activity. Nat Commun 2022; 13:5281. [PMID: 36075900 PMCID: PMC9458634 DOI: 10.1038/s41467-022-32911-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2022] [Accepted: 08/19/2022] [Indexed: 12/02/2022] Open
Abstract
The 3D genome has been shown to be organized into modules including topologically associating domains (TADs) and compartments that are primarily defined by spatial contacts from Hi-C. There exists a gap to investigate whether and how the spatial modularity of the chromatin is related to the functional modularity resulting from chromatin activity. Despite histone modifications reflecting chromatin activity, inferring spatial modularity of the genome directly from the histone modification patterns has not been well explored. Here, we report that histone modifications show a modular pattern (referred to as regulation associated modules, RAMs) that reflects spatial chromatin modularity. Enhancer-promoter interactions, loop anchors, super-enhancer clusters and extrachromosomal DNAs (ecDNAs) are found to occur more often within the same RAMs than within the same TADs. Consistently, compared to the TAD boundaries, deletions of RAM boundaries perturb the chromatin structure more severely (may even cause cell death) and somatic variants in cancer samples are more enriched in RAM boundaries. These observations suggest that RAMs reflect a modular organization of the 3D genome at a scale better aligned with chromatin activity, providing a bridge connecting the structural and functional modularity of the genome.
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31
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Li J, Pertsinidis A. Nanoscale nuclear environments, fine-scale 3D genome organization and transcription regulation. CURRENT OPINION IN SYSTEMS BIOLOGY 2022; 31:100436. [PMID: 37091742 PMCID: PMC10118054 DOI: 10.1016/j.coisb.2022.100436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Decades of in vitro biochemical reconstitution, genetics and structural biology studies have established a vast knowledge base on the molecular mechanisms of chromatin regulation and transcription. A remaining challenge is to understand how these intricate biochemical systems operate in the context of the 3D genome organization and in the crowded and compartmentalized nuclear milieu. Here we review recent progress in this area based on high-resolution imaging approaches.
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Affiliation(s)
- Jieru Li
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, NY 10065, USA
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32
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Tang WC, Liu YT, Yeh CH, Lu CH, Tu CH, Lin YL, Lin YC, Hsu TL, Gao L, Chang SW, Chen P, Chen BC. Optogenetic manipulation of cell migration with high spatiotemporal resolution using lattice lightsheet microscopy. Commun Biol 2022; 5:879. [PMID: 36028551 PMCID: PMC9418249 DOI: 10.1038/s42003-022-03835-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/09/2022] [Indexed: 12/02/2022] Open
Abstract
Lattice lightsheet microscopy (LLSM) featuring three-dimensional recording is improved to manipulate cellular behavior with subcellular resolution through optogenetic activation (optoLLSM). A position-controllable Bessel beam as a stimulation source is integrated into the LLSM to achieve spatiotemporal photoactivation by changing the spatial light modulator (SLM) patterns. Unlike the point-scanning in a confocal microscope, the lattice beams are capable of wide-field optical sectioning for optogenetic activation along the Bessel beam path.We show that the energy power required for optogenetic activations is lower than 1 nW (or 24 mWcm-2) for time-lapses of CRY2olig clustering proteins, and membrane ruffling can be induced at different locations within a cell with subcellular resolution through light-triggered recruitment of phosphoinositide 3-kinase. Moreover, with the epidermal growth factor receptor (EGFR) fused with CRY2olig, we are able to demonstrate guided cell migration using optogenetic stimulation for up to 6 h, where 463 imaging volumes are collected, without noticeable cellular damages. Using a Bessel beam as a simulation source allows the use of lattice lightsheet microscopy for spatiotemporal control of photoactivation, illustrated by the control of cellular migration behavior.
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Affiliation(s)
- Wei-Chun Tang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yen-Ting Liu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Cheng-Han Yeh
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Chieh-Han Lu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Chiao-Hui Tu
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Yi-Ling Lin
- Institute of Biomedical Sciences, Academia Sinica, Taipei, 11529, Taiwan.,Biomedical Translation Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Yu-Chun Lin
- Institute of Molecular Medicine, National Tsing Hua University, Hsinchu, 30013, Taiwan.,Department of Medical Science, National Tsing Hua University, Hsinchu, 30013, Taiwan
| | - Tsui-Ling Hsu
- Genomics Research Center, Academia Sinica, Taipei, 11529, Taiwan
| | - Liang Gao
- Key Laboratory of Structural Biology of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, Zhejiang, 310024, China
| | - Shu-Wei Chang
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan
| | - Peilin Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan. .,Institute of Physics, Academia Sinica, Taipei, 11529, Taiwan.
| | - Bi-Chang Chen
- Research Center for Applied Sciences, Academia Sinica, Taipei, 11529, Taiwan.
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33
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Doerries TJ, Chechkin AV, Metzler R. Apparent anomalous diffusion and non-Gaussian distributions in a simple mobile-immobile transport model with Poissonian switching. J R Soc Interface 2022; 19:20220233. [PMID: 35857918 PMCID: PMC9257594 DOI: 10.1098/rsif.2022.0233] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/15/2022] [Indexed: 09/01/2023] Open
Abstract
We analyse mobile-immobile transport of particles that switch between the mobile and immobile phases with finite rates. Despite this seemingly simple assumption of Poissonian switching, we unveil a rich transport dynamics including significant transient anomalous diffusion and non-Gaussian displacement distributions. Our discussion is based on experimental parameters for tau proteins in neuronal cells, but the results obtained here are expected to be of relevance for a broad class of processes in complex systems. Specifically, we obtain that, when the mean binding time is significantly longer than the mean mobile time, transient anomalous diffusion is observed at short and intermediate time scales, with a strong dependence on the fraction of initially mobile and immobile particles. We unveil a Laplace distribution of particle displacements at relevant intermediate time scales. For any initial fraction of mobile particles, the respective mean squared displacement (MSD) displays a plateau. Moreover, we demonstrate a short-time cubic time dependence of the MSD for immobile tracers when initially all particles are immobile.
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Affiliation(s)
- Timo J. Doerries
- Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
| | - Aleksei V. Chechkin
- Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
- Faculty of Pure and Applied Mathematics, Hugo Steinhaus Center, Wrocław University of Science and Technology, Wyspianskiego 27, 50-370 Wrocław, Poland
- Akhiezer Institute for Theoretical Physics, National Science Center ‘Kharkiv Institute of Physics and Technology’, 61108 Kharkiv, Ukraine
| | - Ralf Metzler
- Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany
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34
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Nollmann M, Bennabi I, Götz M, Gregor T. The Impact of Space and Time on the Functional Output of the Genome. Cold Spring Harb Perspect Biol 2022; 14:a040378. [PMID: 34230036 PMCID: PMC8733053 DOI: 10.1101/cshperspect.a040378] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Over the past two decades, it has become clear that the multiscale spatial and temporal organization of the genome has important implications for nuclear function. This review centers on insights gained from recent advances in light microscopy on our understanding of transcription. We discuss spatial and temporal aspects that shape nuclear order and their consequences on regulatory components, focusing on genomic scales most relevant to function. The emerging picture is that spatiotemporal constraints increase the complexity in transcriptional regulation, highlighting new challenges, such as uncertainty about how information travels from molecular factors through the genome and space to generate a functional output.
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Affiliation(s)
- Marcelo Nollmann
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Isma Bennabi
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
| | - Markus Götz
- Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, Univ Montpellier, 34090 Montpellier, France
| | - Thomas Gregor
- Department of Stem Cell and Developmental Biology, CNRS UMR3738, Institut Pasteur, 75015 Paris, France
- Joseph Henry Laboratory of Physics & Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey 08544, USA
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35
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Kenworthy CA, Haque N, Liou SH, Chandris P, Wong V, Dziuba P, Lavis LD, Liu WL, Singer RH, Coleman RA. Bromodomains regulate dynamic targeting of the PBAF chromatin-remodeling complex to chromatin hubs. Biophys J 2022; 121:1738-1752. [PMID: 35364106 PMCID: PMC9117891 DOI: 10.1016/j.bpj.2022.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/20/2021] [Accepted: 03/24/2022] [Indexed: 11/12/2022] Open
Abstract
Chromatin remodelers actively target arrays of acetylated nucleosomes at select enhancers and promoters to facilitate or shut down the repeated recruitment of RNA polymerase II during transcriptional bursting. It is poorly understood how chromatin remodelers such as PBAF dynamically target different chromatin states inside a live cell. Our live-cell single-molecule fluorescence microscopy study reveals chromatin hubs throughout the nucleus where PBAF rapidly cycles on and off the genome. Deletion of PBAF's bromodomains impairs targeting and stable engagement of chromatin in hubs. Dual color imaging reveals that PBAF targets both euchromatic and heterochromatic hubs with distinct genome-binding kinetic profiles that mimic chromatin stability. Removal of PBAF's bromodomains stabilizes H3.3 binding within chromatin, indicating that bromodomains may play a direct role in remodeling of the nucleosome. Our data suggests that PBAF's dynamic bromodomain-mediated engagement of a nucleosome may reflect the chromatin-remodeling potential of differentially bound chromatin states.
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Affiliation(s)
- Charles A Kenworthy
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Nayem Haque
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Shu-Hao Liou
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Panagiotis Chandris
- Section on High Resolution Optical Imaging, National Institute on Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland
| | - Vincent Wong
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Patrycja Dziuba
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia
| | - Wei-Li Liu
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Robert H Singer
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia
| | - Robert A Coleman
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York.
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36
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Xie L, Dong P, Qi Y, Hsieh THS, English BP, Jung S, Chen X, De Marzio M, Casellas R, Chang HY, Zhang B, Tjian R, Liu Z. BRD2 compartmentalizes the accessible genome. Nat Genet 2022; 54:481-491. [PMID: 35410381 PMCID: PMC9099420 DOI: 10.1038/s41588-022-01044-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Accepted: 03/01/2022] [Indexed: 12/15/2022]
Abstract
Mammalian chromosomes are organized into megabase-sized compartments that are further subdivided into topologically associated domains (TADs). While the formation of TADs is dependent on Cohesin, the mechanism behind compartmentalization remains enigmatic. Here, we show that the bromodomain and extraterminal (BET) family scaffold protein BRD2 promotes spatial mixing and compartmentalization of active chromatin after Cohesin loss. This activity is independent of transcription but requires BRD2 to recognize acetylated targets through its double bromodomain and interact with binding partners with its low complexity domain. Notably, genome compartmentalization mediated by BRD2 is antagonized on one hand by Cohesin and on the other by the BET homolog protein BRD4, both of which inhibit BRD2 binding to chromatin. Polymer simulation of our data supports a BRD2-Cohesin interplay model of nuclear topology, where genome compartmentalization results from a competition between loop extrusion and chromatin state-specific affinity interactions.
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37
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Liu Y, Ding B, Zheng L, Xu P, Liu Z, Chen Z, Wu P, Zhao Y, Pan Q, Guo Y, Wang W, Wei W. Regulatory elements can be essential for maintaining broad chromatin organization and cell viability. Nucleic Acids Res 2022; 50:4340-4354. [PMID: 35390162 PMCID: PMC9071426 DOI: 10.1093/nar/gkac197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Revised: 03/03/2022] [Accepted: 03/15/2022] [Indexed: 11/14/2022] Open
Abstract
Increasing evidence shows that promoters and enhancers could be related to 3D chromatin structure, thus affecting cellular functions. Except for their roles in forming canonical chromatin loops, promoters and enhancers have not been well studied regarding the maintenance of broad chromatin organization. Here, we focused on the active promoters/enhancers predicted to form many 3D contacts with other active promoters/enhancers (referred to as hotspots) and identified dozens of loci essential for cell growth and survival through CRISPR screening. We found that the deletion of an essential hotspot could lead to changes in broad chromatin organization and the expression of distal genes. We showed that the essentiality of hotspots does not result from their association with individual genes that are essential for cell viability but rather from their association with multiple dysregulated non-essential genes to synergistically impact cell fitness.
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Affiliation(s)
- Ying Liu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Bo Ding
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Lina Zheng
- Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Ping Xu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Zhiheng Liu
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Zhao Chen
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Peiyao Wu
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Ying Zhao
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Qian Pan
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Yu Guo
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Wei Wang
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0359, USA.,Bioinformatics and Systems Biology Program, University of California, San Diego, La Jolla, CA 92093-0359, USA.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093-0359, USA
| | - Wensheng Wei
- Biomedical Pioneering Innovation Center, Beijing Advanced Innovation Center for Genomics, Peking-Tsinghua Center for Life Sciences, Peking University Genome Editing Research Center, State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
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38
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de Jonge WJ, Patel HP, Meeussen JVW, Lenstra TL. Following the tracks: how transcription factor binding dynamics control transcription. Biophys J 2022; 121:1583-1592. [PMID: 35337845 PMCID: PMC9117886 DOI: 10.1016/j.bpj.2022.03.026] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 02/28/2022] [Accepted: 03/21/2022] [Indexed: 11/29/2022] Open
Abstract
Transcription, the process of copying genetic information from DNA to messenger RNA, is regulated by sequence-specific DNA binding proteins known as transcription factors (TFs). Recent advances in single-molecule tracking (SMT) technologies have enabled visualization of individual TF molecules as they diffuse and interact with the DNA in the context of living cells. These SMT studies have uncovered multiple populations of DNA binding events characterized by their distinctive DNA residence times. In this perspective, we review recent insights into how these residence times relate to specific and non-specific DNA binding, as well as the contribution of TF domains on the DNA binding dynamics. We discuss different models that aim to link transient DNA binding by TFs to bursts of transcription and present an outlook for how future advances in microscopy development may broaden our understanding of the dynamics of the molecular steps that underlie transcription activation.
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Affiliation(s)
- Wim J de Jonge
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Heta P Patel
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Joseph V W Meeussen
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands
| | - Tineke L Lenstra
- Division of Gene Regulation, The Netherlands Cancer Institute, Oncode Institute, 1066CX Amsterdam, the Netherlands.
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39
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Palacio M, Taatjes DJ. Merging Established Mechanisms with New Insights: Condensates, Hubs, and the Regulation of RNA Polymerase II Transcription. J Mol Biol 2022; 434:167216. [PMID: 34474085 PMCID: PMC8748285 DOI: 10.1016/j.jmb.2021.167216] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/16/2021] [Accepted: 08/19/2021] [Indexed: 01/17/2023]
Abstract
The regulation of RNA polymerase II (pol II) transcription requires a complex and context-specific array of proteins and protein complexes, as well as nucleic acids and metabolites. Every major physiological process requires coordinated transcription of specific sets of genes at the appropriate time, and a breakdown in this regulation is a hallmark of human disease. A proliferation of recent studies has revealed that many general transcription components, including sequence-specific, DNA-binding transcription factors, Mediator, and pol II itself, are capable of liquid-liquid phase separation, to form condensates that partition these factors away from the bulk aqueous phase. These findings hold great promise for next-level understanding of pol II transcription; however, many mechanistic aspects align with more conventional models, and whether phase separation per se regulates pol II activity in cells remains controversial. In this review, we describe the conventional and condensate-dependent models, and why their similarities and differences are important. We also compare and contrast these models in the context of genome organization and pol II transcription (initiation, elongation, and termination), and highlight the central role of RNA in these processes. Finally, we discuss mutations that disrupt normal partitioning of transcription factors, and how this may contribute to disease.
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Affiliation(s)
- Megan Palacio
- Dept. of Biochemistry, University of Colorado, Boulder, CO, USA
| | - Dylan J. Taatjes
- Dept. of Biochemistry, University of Colorado, Boulder, CO, USA,corresponding author;
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40
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Steindel M, Orsine de Almeida I, Strawbridge S, Chernova V, Holcman D, Ponjavic A, Basu S. Studying the Dynamics of Chromatin-Binding Proteins in Mammalian Cells Using Single-Molecule Localization Microscopy. Methods Mol Biol 2022; 2476:209-247. [PMID: 35635707 DOI: 10.1007/978-1-0716-2221-6_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Single-molecule localization microscopy (SMLM) allows the super-resolved imaging of proteins within mammalian nuclei at spatial resolutions comparable to that of a nucleosome itself (~20 nm). The technique is therefore well suited to the study of chromatin structure. Fixed-cell SMLM has already allowed temporal "snapshots" of how proteins are arranged on chromatin within mammalian nuclei. In this chapter, we focus on how recent developments, for example in selective plane illumination, 3D SMLM, and protein labeling, have led to a range of live-cell SMLM studies. We describe how to carry out single-particle tracking (SPT) of single proteins and, by analyzing their diffusion parameters, how to determine whether proteins interact with chromatin, diffuse freely, or do both. We can study the numbers of proteins that interact with chromatin and also determine their residence time on chromatin. We can determine whether these proteins form functional clusters within the nucleus as well as whether they form specific nuclear structures.
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Affiliation(s)
- Maike Steindel
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | | | - Stanley Strawbridge
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - Valentyna Chernova
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK
| | - David Holcman
- Group of Computational Biology and Applied Mathematics, Institute of Biology, Ecole Normale Supérieure, Paris, France
| | - Aleks Ponjavic
- School of Physics and Astronomy and School of Food Science and Nutrition, University of Leeds, Leeds, UK.
| | - Srinjan Basu
- Wellcome-MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, UK.
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41
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Karr JP, Ferrie JJ, Tjian R, Darzacq X. The transcription factor activity gradient (TAG) model: contemplating a contact-independent mechanism for enhancer-promoter communication. Genes Dev 2022; 36:7-16. [PMID: 34969825 PMCID: PMC8763055 DOI: 10.1101/gad.349160.121] [Citation(s) in RCA: 68] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
How distal cis-regulatory elements (e.g., enhancers) communicate with promoters remains an unresolved question of fundamental importance. Although transcription factors and cofactors are known to mediate this communication, the mechanism by which diffusible molecules relay regulatory information from one position to another along the chromosome is a biophysical puzzle-one that needs to be revisited in light of recent data that cannot easily fit into previous solutions. Here we propose a new model that diverges from the textbook enhancer-promoter looping paradigm and offer a synthesis of the literature to make a case for its plausibility, focusing on the coactivator p300.
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Affiliation(s)
- Jonathan P Karr
- University of California at Berkeley, Berkeley, California 94720, USA
| | - John J Ferrie
- University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, Berkeley, California 94720, USA
| | - Robert Tjian
- University of California at Berkeley, Berkeley, California 94720, USA
- Howard Hughes Medical Institute, Berkeley, California 94720, USA
| | - Xavier Darzacq
- University of California at Berkeley, Berkeley, California 94720, USA
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42
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Pluripotency transcription factors at the focus: the phase separation paradigm in stem cells. Biochem Soc Trans 2021; 49:2871-2878. [PMID: 34812855 DOI: 10.1042/bst20210856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 11/02/2021] [Accepted: 11/04/2021] [Indexed: 12/13/2022]
Abstract
The transcription factors (TFs) OCT4, SOX2 and NANOG are key players of the gene regulatory network of pluripotent stem cells. Evidence accumulated in recent years shows that even small imbalances in the expression levels or relative concentrations of these TFs affect both, the maintenance of pluripotency and cell fate decisions. In addition, many components of the transcriptional machinery including RNA polymerases, cofactors and TFs such as those required for pluripotency, do not distribute homogeneously in the nucleus but concentrate in multiple foci influencing the delivery of these molecules to their DNA-targets. How cells control strict levels of available pluripotency TFs in this heterogeneous space and the biological role of these foci remain elusive. In recent years, a wealth of evidence led to propose that many of the nuclear compartments are formed through a liquid-liquid phase separation process. This new paradigm early penetrated the stem cells field since many key players of the pluripotency circuitry seem to phase-separate. Overall, the formation of liquid compartments may modulate the kinetics of biochemical reactions and consequently regulate many nuclear processes. Here, we review the state-of-the-art knowledge of compartmentalization in the cell nucleus and the relevance of this process for transcriptional regulation, particularly in pluripotent stem cells. We also highlight the recent advances and new ideas in the field showing how compartmentalization may affect pluripotency preservation and cell fate decisions.
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43
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Wang Z, Deng W. Dynamic transcription regulation at the single-molecule level. Dev Biol 2021; 482:67-81. [PMID: 34896367 DOI: 10.1016/j.ydbio.2021.11.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 02/07/2023]
Abstract
Cell fate changes during development, differentiation, and reprogramming are largely controlled at the transcription level. The DNA-binding transcription factors (TFs) often act in a combinatorial fashion to alter chromatin states and drive cell type-specific gene expression. Recent advances in fluorescent microscopy technologies have enabled direct visualization of biomolecules involved in the process of transcription and its regulatory events at the single-molecule level in living cells. Remarkably, imaging and tracking individual TF molecules at high temporal and spatial resolution revealed that they are highly dynamic in searching and binding cognate targets, rather than static and binding constantly. In combination with investigation using techniques from biochemistry, structure biology, genetics, and genomics, a more well-rounded view of transcription regulation is emerging. In this review, we briefly cover the technical aspects of live-cell single-molecule imaging and focus on the biological relevance and interpretation of the single-molecule dynamic features of transcription regulatory events observed in the native chromatin environment of living eukaryotic cells. We also discuss how these dynamic features might shed light on mechanistic understanding of transcription regulation.
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Affiliation(s)
- Zuhui Wang
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing, 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Wulan Deng
- Biomedical Pioneering Innovation Center (BIOPIC), Peking University, Beijing, 100871, China; Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China; Beijing Advanced Innovation Center for Genomics (ICG), Peking University, Beijing, 100871, China; Peking-Tsinghua Center for Life Sciences (CLS), Peking University, Beijing, 100871, China; School of Life Sciences, Peking University, Beijing, 100871, China.
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44
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Biswas J, Li W, Singer RH, Coleman RA. Imaging Organization of RNA Processing within the Nucleus. Cold Spring Harb Perspect Biol 2021; 13:a039453. [PMID: 34127450 PMCID: PMC8635003 DOI: 10.1101/cshperspect.a039453] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Within the nucleus, messenger RNA is generated and processed in a highly organized and regulated manner. Messenger RNA processing begins during transcription initiation and continues until the RNA is translated and degraded. Processes such as 5' capping, alternative splicing, and 3' end processing have been studied extensively with biochemical methods and more recently with single-molecule imaging approaches. In this review, we highlight how imaging has helped understand the highly dynamic process of RNA processing. We conclude with open questions and new technological developments that may further our understanding of RNA processing.
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Affiliation(s)
- Jeetayu Biswas
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Weihan Li
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | - Robert A Coleman
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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45
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McCann AJ, Lou J, Moustaqil M, Graus MS, Blum A, Fontaine F, Liu H, Luu W, Rudolffi-Soto P, Koopman P, Sierecki E, Gambin Y, Meunier FA, Liu Z, Hinde E, Francois M. A dominant-negative SOX18 mutant disrupts multiple regulatory layers essential to transcription factor activity. Nucleic Acids Res 2021; 49:10931-10955. [PMID: 34570228 PMCID: PMC8565327 DOI: 10.1093/nar/gkab820] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 08/18/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Few genetically dominant mutations involved in human disease have been fully explained at the molecular level. In cases where the mutant gene encodes a transcription factor, the dominant-negative mode of action of the mutant protein is particularly poorly understood. Here, we studied the genome-wide mechanism underlying a dominant-negative form of the SOX18 transcription factor (SOX18RaOp) responsible for both the classical mouse mutant Ragged Opossum and the human genetic disorder Hypotrichosis-lymphedema-telangiectasia-renal defect syndrome. Combining three single-molecule imaging assays in living cells together with genomics and proteomics analysis, we found that SOX18RaOp disrupts the system through an accumulation of molecular interferences which impair several functional properties of the wild-type SOX18 protein, including its target gene selection process. The dominant-negative effect is further amplified by poisoning the interactome of its wild-type counterpart, which perturbs regulatory nodes such as SOX7 and MEF2C. Our findings explain in unprecedented detail the multi-layered process that underpins the molecular aetiology of dominant-negative transcription factor function.
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Affiliation(s)
- Alex J McCann
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jieqiong Lou
- School of Physics, Department of Biochemistry and Molecular Biology, Bio21, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mehdi Moustaqil
- EMBL Australia Node in Single Molecule Science and School of Medical Sciences, The University of New South Wales, Sydney, NSW 1466, Australia
| | - Matthew S Graus
- The David Richmond Laboratory for Cardio-Vascular Development: gene regulation and editing, The Centenary Institute, Newtown, Sydney, NSW 2006, Australia
| | - Ailisa Blum
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Frank Fontaine
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Hui Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, United States
| | - Winnie Luu
- The David Richmond Laboratory for Cardio-Vascular Development: gene regulation and editing, The Centenary Institute, Newtown, Sydney, NSW 2006, Australia
| | - Paulina Rudolffi-Soto
- EMBL Australia Node in Single Molecule Science and School of Medical Sciences, The University of New South Wales, Sydney, NSW 1466, Australia
| | - Peter Koopman
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Emma Sierecki
- EMBL Australia Node in Single Molecule Science and School of Medical Sciences, The University of New South Wales, Sydney, NSW 1466, Australia
| | - Yann Gambin
- EMBL Australia Node in Single Molecule Science and School of Medical Sciences, The University of New South Wales, Sydney, NSW 1466, Australia
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, United States
| | - Elizabeth Hinde
- School of Physics, Department of Biochemistry and Molecular Biology, Bio21, The University of Melbourne, Melbourne, VIC 3010, Australia
| | - Mathias Francois
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.,The David Richmond Laboratory for Cardio-Vascular Development: gene regulation and editing, The Centenary Institute, Newtown, Sydney, NSW 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia
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46
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Mancebo A, Mehra D, Banerjee C, Kim DH, Puchner EM. Efficient Cross-Correlation Filtering of One- and Two-Color Single Molecule Localization Microscopy Data. FRONTIERS IN BIOINFORMATICS 2021; 1:739769. [PMID: 36303727 PMCID: PMC9581065 DOI: 10.3389/fbinf.2021.739769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Accepted: 10/14/2021] [Indexed: 11/25/2022] Open
Abstract
Single molecule localization microscopy has become a prominent technique to quantitatively study biological processes below the optical diffraction limit. By fitting the intensity profile of single sparsely activated fluorophores, which are often attached to a specific biomolecule within a cell, the locations of all imaged fluorophores are obtained with ∼20 nm resolution in the form of a coordinate table. While rendered super-resolution images reveal structural features of intracellular structures below the optical diffraction limit, the ability to further analyze the molecular coordinates presents opportunities to gain additional quantitative insights into the spatial distribution of a biomolecule of interest. For instance, pair-correlation or radial distribution functions are employed as a measure of clustering, and cross-correlation analysis reveals the colocalization of two biomolecules in two-color SMLM data. Here, we present an efficient filtering method for SMLM data sets based on pair- or cross-correlation to isolate localizations that are clustered or appear in proximity to a second set of localizations in two-color SMLM data. In this way, clustered or colocalized localizations can be separately rendered and analyzed to compare other molecular properties to the remaining localizations, such as their oligomeric state or mobility in live cell experiments. Current matrix-based cross-correlation analyses of large data sets quickly reach the limitations of computer memory due to the space complexity of constructing the distance matrices. Our approach leverages k-dimensional trees to efficiently perform range searches, which dramatically reduces memory needs and the time for the analysis. We demonstrate the versatile applications of this method with simulated data sets as well as examples of two-color SMLM data. The provided MATLAB code and its description can be integrated into existing localization analysis packages and provides a useful resource to analyze SMLM data with new detail.
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Affiliation(s)
- Angel Mancebo
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, United States
| | - Dushyant Mehra
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, United States
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Chiranjib Banerjee
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, United States
| | - Do-Hyung Kim
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, United States
| | - Elias M. Puchner
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, United States
- *Correspondence: Elias M. Puchner,
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47
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Abstract
To predict transcription, one needs a mechanistic understanding of how the numerous required transcription factors (TFs) explore the nuclear space to find their target genes, assemble, cooperate, and compete with one another. Advances in fluorescence microscopy have made it possible to visualize real-time TF dynamics in living cells, leading to two intriguing observations: first, most TFs contact chromatin only transiently; and second, TFs can assemble into clusters through their intrinsically disordered regions. These findings suggest that highly dynamic events and spatially structured nuclear microenvironments might play key roles in transcription regulation that are not yet fully understood. The emerging model is that while some promoters directly convert TF-binding events into on/off cycles of transcription, many others apply complex regulatory layers that ultimately lead to diverse phenotypic outputs. Cracking this kinetic code is an ongoing and challenging task that is made possible by combining innovative imaging approaches with biophysical models.
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Affiliation(s)
- Feiyue Lu
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
| | - Timothée Lionnet
- Institute for Systems Genetics and Cell Biology Department, NYU School of Medicine, New York, New York 10016, USA
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48
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Bian E, Chen X, Cheng L, Cheng M, Chen Z, Yue X, Zhang Z, Chen J, Sun L, Huang K, Huang C, Fang Z, Zhao B, Li J. Super-enhancer-associated TMEM44-AS1 aggravated glioma progression by forming a positive feedback loop with Myc. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2021; 40:337. [PMID: 34696771 PMCID: PMC8543865 DOI: 10.1186/s13046-021-02129-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/05/2021] [Indexed: 01/05/2023]
Abstract
Background Long non-coding RNAs (lncRNAs) have been considered as one type of gene expression regulator for cancer development, but it is not clear how these are regulated. This study aimed to identify a specific lncRNA that promotes glioma progression. Methods RNA sequencing (RNA-seq) and quantitative real-time PCR were performed to screen differentially expressed genes. CCK-8, transwell migration, invasion assays, and a mouse xenograft model were performed to determine the functions of TMEM44-AS1. Co-IP, ChIP, Dual-luciferase reporter assays, RNA pulldown, and RNA immunoprecipitation assays were performed to study the molecular mechanism of TMEM44-AS1 and the downstream target. Results We identified a novel lncRNA TMEM44-AS1, which was aberrantly expressed in glioma tissues, and that increased TMEM44-AS1 expression was correlated with malignant progression and poor survival for patients with glioma. Expression of TMEM44-AS1 increased the proliferation, colony formation, migration, and invasion of glioma cells. Knockdown of TMEM44-AS1 in glioma cells reduced cell proliferation, colony formation, migration and invasion, and tumor growth in a nude mouse xenograft model. Mechanistically, TMEM44-AS1 is directly bound to the SerpinB3, and sequentially activated Myc and EGR1/IL-6 signaling; Myc transcriptionally induced TMEM44-AS1 and directly bound to the promoter and super-enhancer of TMEM44-AS1, thus forming a positive feedback loop with TMEM44-AS. Further studies demonstrated that Myc interacts with MED1 regulates the super-enhancer of TMEM44-AS1. More importantly, a novel small-molecule Myc inhibitor, Myci975, alleviated TMEM44-AS1-promoted the growth of glioma cells. Conclusions Our study implicates a crucial role of the TMEM44-AS1-Myc axis in glioma progression and provides a possible anti-glioma therapeutic agent. Supplementary Information The online version contains supplementary material available at 10.1186/s13046-021-02129-9.
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Affiliation(s)
- Erbao Bian
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China. .,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China.
| | - Xueran Chen
- Department of Laboratory Medicine, Hefei Cancer Hospital, Chinese Academy of Sciences, No. 350, Shushan Hu Road, Hefei, 230031, Anhui, China.,Anhui Province Key Laboratory of Medical Physics and Technology; Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, No. 350, Shushan Hu Road, Hefei, 230031, Anhui, China
| | - Li Cheng
- School of pharmacy, Anhui Medical University, Hefei, 230032, China
| | - Meng Cheng
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Zhigang Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Xiaoyu Yue
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Zhengwei Zhang
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Jie Chen
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Libo Sun
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Kebing Huang
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China.,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China
| | - Cheng Huang
- School of pharmacy, Anhui Medical University, Hefei, 230032, China
| | - Zhiyou Fang
- Department of Laboratory Medicine, Hefei Cancer Hospital, Chinese Academy of Sciences, No. 350, Shushan Hu Road, Hefei, 230031, Anhui, China. .,Anhui Province Key Laboratory of Medical Physics and Technology; Institute of Health and Medical Technology, Hefei Institutes of Physical Science, Chinese Academy of Sciences, No. 350, Shushan Hu Road, Hefei, 230031, Anhui, China.
| | - Bing Zhao
- Department of Neurosurgery, The Second Affiliated Hospital of Anhui Medical University, Hefei, 230601, China. .,Cerebral Vascular Disease Research Center, Anhui Medical University, Hefei, 230601, China.
| | - Jun Li
- School of pharmacy, Anhui Medical University, Hefei, 230032, China.
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49
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Volumetric interferometric lattice light-sheet imaging. Nat Biotechnol 2021; 39:1385-1393. [PMID: 34635835 PMCID: PMC8595582 DOI: 10.1038/s41587-021-01042-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 07/29/2021] [Indexed: 01/20/2023]
Abstract
Live-cell imaging with high spatiotemporal resolution and high detection sensitivity facilitates the study of the dynamics of cellular structure and function. However, extracting high-resolution 4D (3D space plus time) information from live cells remains challenging, because current methods are slow, require high peak excitation intensities or suffer from high out-of-focus background. Here we present 3D interferometric lattice light-sheet (3D-iLLS) imaging, a technique that requires low excitation light levels and provides high background suppression and substantially improved volumetric resolution by combining 4Pi interferometry with selective plane illumination. We demonstrate that 3D-iLLS has an axial resolution and single-particle localization precision of 100 nm (FWHM) and <10 nm (1σ), respectively. We illustrate the performance of 3D-iLLS in a range of systems: single messenger RNA molecules, nanoscale assemblies of transcription regulators in the nucleus, the microtubule cytoskeleton, and mitochondria organelles. The enhanced 4D resolution and increased signal-to-noise ratio (SNR) of 3D-iLLS will facilitate the analysis of biological processes at the sub-cellular level.
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50
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Boka AP, Mukherjee A, Mir M. Single-molecule tracking technologies for quantifying the dynamics of gene regulation in cells, tissue and embryos. Development 2021; 148:272071. [PMID: 34490887 DOI: 10.1242/dev.199744] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
For decades, we have relied on population and time-averaged snapshots of dynamic molecular scale events to understand how genes are regulated during development and beyond. The advent of techniques to observe single-molecule kinetics in increasingly endogenous contexts, progressing from in vitro studies to living embryos, has revealed how much we have missed. Here, we provide an accessible overview of the rapidly expanding family of technologies for single-molecule tracking (SMT), with the goal of enabling the reader to critically analyse single-molecule studies, as well as to inspire the application of SMT to their own work. We start by overviewing the basics of and motivation for SMT experiments, and the trade-offs involved when optimizing parameters. We then cover key technologies, including fluorescent labelling, excitation and detection optics, localization and tracking algorithms, and data analysis. Finally, we provide a summary of selected recent applications of SMT to study the dynamics of gene regulation.
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Affiliation(s)
- Alan P Boka
- Biochemistry and Molecular Biophysics Graduate Group, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Apratim Mukherjee
- Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA
| | - Mustafa Mir
- Center for Computational and Genomic Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.,Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
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