1
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Wong VC, Houlihan PR, Liu H, Walpita D, DeSantis MC, Liu Z, O'Shea EK. Plasticity-induced actin polymerization in the dendritic shaft regulates intracellular AMPA receptor trafficking. eLife 2024; 13:e80622. [PMID: 39146380 PMCID: PMC11326776 DOI: 10.7554/elife.80622] [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: 05/27/2022] [Accepted: 07/09/2024] [Indexed: 08/17/2024] Open
Abstract
AMPA-type receptors (AMPARs) are rapidly inserted into synapses undergoing plasticity to increase synaptic transmission, but it is not fully understood if and how AMPAR-containing vesicles are selectively trafficked to these synapses. Here, we developed a strategy to label AMPAR GluA1 subunits expressed from their endogenous loci in cultured rat hippocampal neurons and characterized the motion of GluA1-containing vesicles using single-particle tracking and mathematical modeling. We find that GluA1-containing vesicles are confined and concentrated near sites of stimulation-induced structural plasticity. We show that confinement is mediated by actin polymerization, which hinders the active transport of GluA1-containing vesicles along the length of the dendritic shaft by modulating the rheological properties of the cytoplasm. Actin polymerization also facilitates myosin-mediated transport of GluA1-containing vesicles to exocytic sites. We conclude that neurons utilize F-actin to increase vesicular GluA1 reservoirs and promote exocytosis proximal to the sites of synaptic activity.
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Affiliation(s)
- Victor C Wong
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Patrick R Houlihan
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Hui Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Deepika Walpita
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Michael C DeSantis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Erin K O'Shea
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
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2
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Peng CS, Zhang Y, Liu Q, Marti GE, Huang YWA, Südhof TC, Cui B, Chu S. Nanometer-resolution tracking of single cargo reveals dynein motor mechanisms. Nat Chem Biol 2024:10.1038/s41589-024-01694-2. [PMID: 39090313 DOI: 10.1038/s41589-024-01694-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Accepted: 07/09/2024] [Indexed: 08/04/2024]
Abstract
Cytoplasmic dynein is essential for intracellular transport. Despite extensive in vitro characterizations, how the dynein motors transport vesicles by processive steps in live cells remains unclear. To dissect the molecular mechanisms of dynein, we develop optical probes that enable long-term single-particle tracking in live cells with high spatiotemporal resolution. We find that the number of active dynein motors transporting cargo switches stochastically between one and five dynein motors during long-range transport in neuronal axons. Our very bright optical probes allow the observation of individual molecular steps. Strikingly, these measurements reveal that the dwell times between steps are controlled by two temperature-dependent rate constants in which two ATP molecules are hydrolyzed sequentially during each dynein step. Thus, our observations uncover a previously unknown chemomechanical cycle of dynein-mediated cargo transport in living cells.
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Affiliation(s)
- Chunte Sam Peng
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Yunxiang Zhang
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - Qian Liu
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Department of Chemistry and Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Fudan University, Shanghai, China
| | - G Edward Marti
- Department of Physics, Stanford University, Stanford, CA, USA
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
| | - Yu-Wen Alvin Huang
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
- Department of Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Thomas C Südhof
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Bianxiao Cui
- Department of Chemistry, Stanford University, Stanford, CA, USA
| | - Steven Chu
- Department of Physics, Stanford University, Stanford, CA, USA.
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA, USA.
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3
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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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4
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Presman DM, Benítez B, Lafuente AL, Vázquez Lareu A. Chromatin structure and dynamics: one nucleosome at a time. Histochem Cell Biol 2024; 162:79-90. [PMID: 38607419 DOI: 10.1007/s00418-024-02281-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/19/2024] [Indexed: 04/13/2024]
Abstract
Eukaryotic genomes store information on many levels, including their linear DNA sequence, the posttranslational modifications of its constituents (epigenetic modifications), and its three-dimensional folding. Understanding how this information is stored and read requires multidisciplinary collaborations from many branches of science beyond biology, including physics, chemistry, and computer science. Concurrent recent developments in all these areas have enabled researchers to image the genome with unprecedented spatial and temporal resolution. In this review, we focus on what single-molecule imaging and tracking of individual proteins in live cells have taught us about chromatin structure and dynamics. Starting with the basics of single-molecule tracking (SMT), we describe some advantages over in situ imaging techniques and its current limitations. Next, we focus on single-nucleosome studies and what they have added to our current understanding of the relationship between chromatin dynamics and transcription. In celebration of Robert Feulgen's ground-breaking discovery that allowed us to start seeing the genome, we discuss current models of chromatin structure and future challenges ahead.
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Affiliation(s)
- Diego M Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
- Departamento de Fisiología, Biología Molecular y Celular, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
| | - Belén Benítez
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Agustina L Lafuente
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Alejo Vázquez Lareu
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
- Instituto de Química Biológica (IQUIBICEN), Facultad de Ciencias Exactas y Naturales, CONICET-Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
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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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Fitz GN, Tyska MJ. Molecular counting of myosin force generators in growing filopodia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.14.593924. [PMID: 38798618 PMCID: PMC11118519 DOI: 10.1101/2024.05.14.593924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2024]
Abstract
Animal cells build actin-based surface protrusions to enable biological activities ranging from cell motility to mechanosensation to solute uptake. Long-standing models of protrusion growth suggest that actin filament polymerization provides the primary mechanical force for "pushing" the plasma membrane outward at the distal tip. Expanding on these actin-centric models, our recent studies used a chemically inducible system to establish that plasma membrane-bound myosin motors, which are abundant in protrusions and accumulate at the distal tips, can also power robust filopodial growth. How protrusion resident myosins coordinate with actin polymerization to drive elongation remains unclear, in part because the number of force generators and thus, the scale of their mechanical contributions remain undefined. To address this gap, we leveraged the SunTag system to count membrane-bound myosin motors in actively growing filopodia. Using this approach, we found that the number of myosins is log-normally distributed with a mean of 12.0 ± 2.5 motors [GeoMean ± GeoSD] per filopodium. Together with unitary force values and duty ratio estimates derived from biophysical studies for the motor used in these experiments, we calculate that a distal tip population of myosins could generate a time averaged force of ∼tens of pN to elongate filopodia. This range is comparable to the expected force production of actin polymerization in this system, a point that necessitates revision of popular physical models for protrusion growth. SIGNIFICANCE STATEMENT This study describes the results of in-cell molecular counting experiments to define the number of myosin motors that are mechanically active in growing filopodia. This data should be used to constrain future physical models of the formation of actin-based protrusions.
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7
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DeHaro-Arbona FJ, Roussos C, Baloul S, Townson J, Gómez Lamarca MJ, Bray S. Dynamic modes of Notch transcription hubs conferring memory and stochastic activation revealed by live imaging the co-activator Mastermind. eLife 2024; 12:RP92083. [PMID: 38727722 PMCID: PMC11087053 DOI: 10.7554/elife.92083] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/12/2024] Open
Abstract
Developmental programming involves the accurate conversion of signalling levels and dynamics to transcriptional outputs. The transcriptional relay in the Notch pathway relies on nuclear complexes containing the co-activator Mastermind (Mam). By tracking these complexes in real time, we reveal that they promote the formation of a dynamic transcription hub in Notch ON nuclei which concentrates key factors including the Mediator CDK module. The composition of the hub is labile and persists after Notch withdrawal conferring a memory that enables rapid reformation. Surprisingly, only a third of Notch ON hubs progress to a state with nascent transcription, which correlates with polymerase II and core Mediator recruitment. This probability is increased by a second signal. The discovery that target-gene transcription is probabilistic has far-reaching implications because it implies that stochastic differences in Notch pathway output can arise downstream of receptor activation.
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Affiliation(s)
- F Javier DeHaro-Arbona
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Charalambos Roussos
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Sarah Baloul
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - Jonathan Townson
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
| | - María J Gómez Lamarca
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocıo/CSIC/Universidad de Sevilla, Departamento de Biologıa CelularSevilleSpain
| | - Sarah Bray
- Department of Physiology Development and Neuroscience, University of CambridgeCambridgeUnited Kingdom
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8
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F Shida J, Ma K, Toll HW, Salinas O, Ma X, Peng CS. Multicolor Long-Term Single-Particle Tracking Using 10 nm Upconverting Nanoparticles. NANO LETTERS 2024; 24:4194-4201. [PMID: 38497588 DOI: 10.1021/acs.nanolett.4c00207] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Single-particle tracking (SPT) is a powerful technique to unveil molecular behaviors crucial to the understanding of many biological processes, but it is limited by factors such as probe photostability and spectral orthogonality. To overcome these limitations, we develop upconverting nanoparticles (UCNPs), which are photostable over several hours at the single-particle level, enabling long-term multicolor SPT. We investigate the brightness of core-shell UCNPs as a function of inert shell thickness to minimize particle size while maintaining sufficient signal for SPT. We explore different rare-earth dopants to optimize for the brightest probes and find that UCNPs doped with 2% Tm3+/30% Yb3+, 10% Er3+/90% Yb3+, and 15% Tm3+/85% Yb3+ represent the optimal probes for blue, green, and near-infrared emission, respectively. The multiplexed 10 nm probes enable three-color single-particle tracking on live HeLa cells for tens of minutes using a single, near-infrared excitation source. These photostable and multiplexed probes open new avenues for numerous biological applications.
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Affiliation(s)
- João F Shida
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
| | - Kaibo Ma
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
| | - Harrison W Toll
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
| | - Omar Salinas
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
| | - Xiaojie Ma
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
| | - Chunte Sam Peng
- Department of Chemistry, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139, United States
- Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02139, United States
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9
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Van HT, Xie G, Dong P, Liu Z, Ge K. KMT2 Family of H3K4 Methyltransferases: Enzymatic Activity-dependent and -independent Functions. J Mol Biol 2024; 436:168453. [PMID: 38266981 PMCID: PMC10957308 DOI: 10.1016/j.jmb.2024.168453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 01/26/2024]
Abstract
Histone-lysine N-methyltransferase 2 (KMT2) methyltransferases are critical for gene regulation, cell differentiation, animal development, and human diseases. KMT2 biological roles are often attributed to their methyltransferase activities on lysine 4 of histone H3 (H3K4). However, recent data indicate that KMT2 proteins also possess non-enzymatic functions. In this review, we discuss the current understanding of KMT2 family, with a focus on their enzymatic activity-dependent and -independent functions. Six mammalian KMT2 proteins of three subgroups, KMT2A/B (MLL1/2), KMT2C/D (MLL3/4), and KMT2F/G (SETD1A/B or SET1A/B), have shared and distinct protein domains, catalytic substrates, genomic localizations, and associated complex subunits. Recent studies have revealed the importance of KMT2C/D in enhancer regulation, differentiation, development, tumor suppression and highlighted KMT2C/D enzymatic activity-dependent and -independent roles in mouse embryonic development and cell differentiation. Catalytic dependent and independent functions for KMT2A/B and KMT2F/G in gene regulation, differentiation, and development are less understood. Finally, we provide our perspectives and lay out future research directions that may help advance the investigation on enzymatic activity-dependent and -independent biological roles and working mechanisms of KMT2 methyltransferases.
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Affiliation(s)
- Hieu T Van
- Adipocyte Biology and Gene Regulation Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 50, Room 4149, 50 South Dr, Bethesda, MD 20892, USA.
| | - Guojia Xie
- Adipocyte Biology and Gene Regulation Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 50, Room 4149, 50 South Dr, Bethesda, MD 20892, USA.
| | - Peng Dong
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA.
| | - Kai Ge
- Adipocyte Biology and Gene Regulation Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 50, Room 4149, 50 South Dr, Bethesda, MD 20892, USA.
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10
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Zhang Y, Zhang N, Chai X, Sun T. Machine learning for image-based multi-omics analysis of leaf veins. JOURNAL OF EXPERIMENTAL BOTANY 2023; 74:4928-4941. [PMID: 37410807 DOI: 10.1093/jxb/erad251] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2023] [Accepted: 06/29/2023] [Indexed: 07/08/2023]
Abstract
Veins are a critical component of the plant growth and development system, playing an integral role in supporting and protecting leaves, as well as transporting water, nutrients, and photosynthetic products. A comprehensive understanding of the form and function of veins requires a dual approach that combines plant physiology with cutting-edge image recognition technology. The latest advancements in computer vision and machine learning have facilitated the creation of algorithms that can identify vein networks and explore their developmental progression. Here, we review the functional, environmental, and genetic factors associated with vein networks, along with the current status of research on image analysis. In addition, we discuss the methods of venous phenotype extraction and multi-omics association analysis using machine learning technology, which could provide a theoretical basis for improving crop productivity by optimizing the vein network architecture.
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Affiliation(s)
- Yubin Zhang
- Agricultural Information Institute, Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St, Beijing 100081, China
| | - Ning Zhang
- Agricultural Information Institute, Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St, Beijing 100081, China
| | - Xiujuan Chai
- Agricultural Information Institute, Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St, Beijing 100081, China
| | - Tan Sun
- Key Laboratory of Agricultural Big Data, Ministry of Agriculture and Rural Affairs, Beijing, China
- Chinese Academy of Agricultural Sciences, No.12 Zhongguancun South St, Beijing 100081, China
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11
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Hellweg L, Edenhofer A, Barck L, Huppertz MC, Frei MS, Tarnawski M, Bergner A, Koch B, Johnsson K, Hiblot J. A general method for the development of multicolor biosensors with large dynamic ranges. Nat Chem Biol 2023; 19:1147-1157. [PMID: 37291200 PMCID: PMC10449634 DOI: 10.1038/s41589-023-01350-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 04/25/2023] [Indexed: 06/10/2023]
Abstract
Fluorescent biosensors enable the study of cell physiology with spatiotemporal resolution; yet, most biosensors suffer from relatively low dynamic ranges. Here, we introduce a family of designed Förster resonance energy transfer (FRET) pairs with near-quantitative FRET efficiencies based on the reversible interaction of fluorescent proteins with a fluorescently labeled HaloTag. These FRET pairs enabled the straightforward design of biosensors for calcium, ATP and NAD+ with unprecedented dynamic ranges. The color of each of these biosensors can be readily tuned by changing either the fluorescent protein or the synthetic fluorophore, which enables simultaneous monitoring of free NAD+ in different subcellular compartments following genotoxic stress. Minimal modifications of these biosensors furthermore allow their readout to be switched to fluorescence intensity, fluorescence lifetime or bioluminescence. These FRET pairs thus establish a new concept for the development of highly sensitive and tunable biosensors.
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Affiliation(s)
- Lars Hellweg
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Anna Edenhofer
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Lucas Barck
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Magnus-Carsten Huppertz
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Michelle S Frei
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Miroslaw Tarnawski
- Protein Expression and Characterization Facility, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Andrea Bergner
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Birgit Koch
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
| | - Kai Johnsson
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany
- Institute of Chemical Sciences and Engineering (ISIC), École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Julien Hiblot
- Department of Chemical Biology, Max Planck Institute for Medical Research, Heidelberg, Germany.
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12
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Yi Y, Zhong C, Wei-wei H. The long-term neurodevelopmental outcomes of febrile seizures and underlying mechanisms. Front Cell Dev Biol 2023; 11:1186050. [PMID: 37305674 PMCID: PMC10248510 DOI: 10.3389/fcell.2023.1186050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 05/16/2023] [Indexed: 06/13/2023] Open
Abstract
Febrile seizures (FSs) are convulsions caused by a sudden increase in body temperature during a fever. FSs are one of the commonest presentations in young children, occurring in up to 4% of children between the ages of about 6 months and 5 years old. FSs not only endanger children's health, cause panic and anxiety to families, but also have many adverse consequences. Both clinical and animal studies show that FSs have detrimental effects on neurodevelopment, that cause attention deficit hyperactivity disorder (ADHD), increased susceptibility to epilepsy, hippocampal sclerosis and cognitive decline during adulthood. However, the mechanisms of FSs in developmental abnormalities and disease occurrence during adulthood have not been determined. This article provides an overview of the association of FSs with neurodevelopmental outcomes, outlining both the underlying mechanisms and the possible appropriate clinical biomarkers, from histological changes to cellular molecular mechanisms. The hippocampus is the brain region most significantly altered after FSs, but the motor cortex and subcortical white matter may also be involved in the development disorders induced by FSs. The occurrence of multiple diseases after FSs may share common mechanisms, and the long-term role of inflammation and γ-aminobutyric acid (GABA) system are currently well studied.
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Affiliation(s)
- You Yi
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
| | - Chen Zhong
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
- Key Laboratory of Neuropharmacology and Translational Medicine of Zhejiang Province, Zhejiang Chinese Medical University, Hangzhou, China
| | - Hu Wei-wei
- Department of Pharmacology and Department of Pharmacy of the Second Affiliated Hospital, Key Laboratory of Medical Neurobiology of the Ministry of Health of China, Zhejiang University School of Medicine, Hangzhou, China
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13
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Schaich MA, Schnable BL, Kumar N, Roginskaya V, Jakielski R, Urban R, Zhong Z, Kad NM, Van Houten B. Single-molecule analysis of DNA-binding proteins from nuclear extracts (SMADNE). Nucleic Acids Res 2023; 51:e39. [PMID: 36861323 PMCID: PMC10123111 DOI: 10.1093/nar/gkad095] [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: 06/11/2022] [Revised: 01/19/2023] [Accepted: 02/08/2023] [Indexed: 03/03/2023] Open
Abstract
Single-molecule characterization of protein-DNA dynamics provides unprecedented mechanistic details about numerous nuclear processes. Here, we describe a new method that rapidly generates single-molecule information with fluorescently tagged proteins isolated from nuclear extracts of human cells. We demonstrated the wide applicability of this novel technique on undamaged DNA and three forms of DNA damage using seven native DNA repair proteins and two structural variants, including: poly(ADP-ribose) polymerase (PARP1), heterodimeric ultraviolet-damaged DNA-binding protein (UV-DDB), and 8-oxoguanine glycosylase 1 (OGG1). We found that PARP1 binding to DNA nicks is altered by tension, and that UV-DDB did not act as an obligate heterodimer of DDB1 and DDB2 on UV-irradiated DNA. UV-DDB bound to UV photoproducts with an average lifetime of 39 seconds (corrected for photobleaching, τc), whereas binding lifetimes to 8-oxoG adducts were < 1 second. Catalytically inactive OGG1 variant K249Q bound oxidative damage 23-fold longer than WT OGG1, at 47 and 2.0 s, respectively. By measuring three fluorescent colors simultaneously, we also characterized the assembly and disassembly kinetics of UV-DDB and OGG1 complexes on DNA. Hence, the SMADNE technique represents a novel, scalable, and universal method to obtain single-molecule mechanistic insights into key protein-DNA interactions in an environment containing physiologically-relevant nuclear proteins.
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Affiliation(s)
- Matthew A Schaich
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
| | - Brittani L Schnable
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Biophysics and Structural Biology Program, University of Pittsburgh, Pittsburgh, PA, USA
| | - Namrata Kumar
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | | | - Rachel C Jakielski
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
| | - Roman Urban
- School of Biosciences, University of Kent, Kent, UK
| | - Zhou Zhong
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- LUMICKS, Waltham, MA, USA
| | - Neil M Kad
- School of Biosciences, University of Kent, Kent, UK
| | - Bennett Van Houten
- Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- UPMC-Hillman Cancer Center, Pittsburgh, PA, 15232, USA
- Molecular Genetics and Developmental Biology Graduate Program, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
- Molecular Biophysics and Structural Biology Program, University of Pittsburgh, Pittsburgh, PA, USA
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14
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Single-molecule tracking (SMT): a window into live-cell transcription biochemistry. Biochem Soc Trans 2023; 51:557-569. [PMID: 36876879 DOI: 10.1042/bst20221242] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/15/2023] [Accepted: 02/16/2023] [Indexed: 03/07/2023]
Abstract
How molecules interact governs how they move. Single-molecule tracking (SMT) thus provides a unique window into the dynamic interactions of biomolecules within live cells. Using transcription regulation as a case study, we describe how SMT works, what it can tell us about molecular biology, and how it has changed our perspective on the inner workings of the nucleus. We also describe what SMT cannot yet tell us and how new technical advances seek to overcome its limitations. This ongoing progress will be imperative to address outstanding questions about how dynamic molecular machines function in live cells.
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15
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Kang F, Xie L, Qin T, Miao Y, Kang Y, Takahashi T, Liang T, Xie H, Gaisano HY. Plasma membrane flipping of Syntaxin-2 regulates its inhibitory action on insulin granule exocytosis. Nat Commun 2022; 13:6512. [PMID: 36316316 PMCID: PMC9622911 DOI: 10.1038/s41467-022-33986-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 10/05/2022] [Indexed: 11/07/2022] Open
Abstract
Enhancing pancreatic β-cell secretion is a primary therapeutic target for type-2 diabetes (T2D). Syntaxin-2 (Stx2) has just been identified to be an inhibitory SNARE for insulin granule exocytosis, holding potential as a treatment for T2D, yet its molecular underpinnings remain unclear. We show that excessive Stx2 recruitment to raft-like granule docking sites at higher binding affinity than pro-fusion syntaxin-1A effectively competes for and inhibits fusogenic SNARE machineries. Depletion of Stx2 in human β-cells improves insulin secretion by enhancing trans-SNARE complex assembly and cis-SNARE disassembly. Using a genetically-encoded reporter, glucose stimulation is shown to induce Stx2 flipping across the plasma membrane, which relieves its suppression of cytoplasmic fusogenic SNARE complexes to promote insulin secretion. Targeting the flipping efficiency of Stx2 profoundly modulates secretion, which could restore the impaired insulin secretion in diabetes. Here, we show that Stx2 acts to assist this precise tuning of insulin secretion in β-cells, including in diabetes.
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Affiliation(s)
- Fei Kang
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada ,grid.231844.80000 0004 0474 0428Toronto General Hospital Research Institute, University Health Network, 200 Elizabeth Street, Toronto, ON M5G 2C4 Canada
| | - Li Xie
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Tairan Qin
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Yifan Miao
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Youhou Kang
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Toshimasa Takahashi
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Tao Liang
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada ,grid.231844.80000 0004 0474 0428Toronto General Hospital Research Institute, University Health Network, 200 Elizabeth Street, Toronto, ON M5G 2C4 Canada
| | - Huanli Xie
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada
| | - Herbert Y. Gaisano
- grid.17063.330000 0001 2157 2938Department of Medicine, Temerty Faculty of Medicine, University of Toronto, Toronto, ON M5S 1A8 Canada ,grid.231844.80000 0004 0474 0428Toronto General Hospital Research Institute, University Health Network, 200 Elizabeth Street, Toronto, ON M5G 2C4 Canada
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16
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Ng KK, Prescher JA. Generalized Bioluminescent Platform To Observe and Track Cellular Interactions. Bioconjug Chem 2022; 33:1876-1884. [PMID: 36166258 DOI: 10.1021/acs.bioconjchem.2c00348] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cell-to-cell communications are critical to biological processes ranging from embryonic development to cancer progression. Several imaging strategies have been developed to capture such interactions, but many are challenging to deploy in thick tissues and other complex environments. Here, we report a platform termed Luminescence to Observe and Track Intercellular Interactions (LOTIIS). The approach features split fragments of a luciferase enzyme that reassemble when target cells come into proximity. One fragment is secreted by "sender" cells, and the complementary piece is secreted by "receiver" cells. Split reporter assembly is facilitated by a single chain variable fragment (scFv)-peptide interaction on the receiver cell, resulting in localized light production. We demonstrate that LOTIIS can rapidly label cells in close proximity in a time- and distance-dependent fashion. The platform is also compatible with bioluminescence resonance energy transfer probes for multiplexed imaging. Collectively, these data suggest that LOTIIS will enable a variety of cellular interactions to be tracked in biological settings.
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Affiliation(s)
- Kevin K Ng
- Departments of Pharmaceutical Sciences, University of California, Irvine, California 92697, United States
| | - Jennifer A Prescher
- Departments of Pharmaceutical Sciences, University of California, Irvine, California 92697, United States.,Departments of Chemistry, University of California, Irvine, California 92697, United States.,Molecular Biology and Biochemistry, University of California, Irvine, California 92697, United States
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17
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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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18
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Liu H, Wang HG, Pitt G, Liu Z. Direct Observation of Compartment-Specific Localization and Dynamics of Voltage-Gated Sodium Channels. J Neurosci 2022; 42:5482-5498. [PMID: 35672149 PMCID: PMC9295844 DOI: 10.1523/jneurosci.0086-22.2022] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/15/2022] [Accepted: 05/18/2022] [Indexed: 11/21/2022] Open
Abstract
Brain enriched voltage-gated sodium channel (VGSC) Nav1.2 and Nav1.6 are critical for electrical signaling in the CNS. Previous studies have extensively characterized cell-type-specific expression and electrophysiological properties of these two VGSCs and how their differences contribute to fine-tuning of neuronal excitability. However, because of a lack of reliable labeling and imaging methods, the subcellular localization and dynamics of these homologous Nav1.2 and Nav1.6 channels remain understudied. To overcome this challenge, we combined genome editing, super-resolution, and live-cell single-molecule imaging to probe subcellular composition, relative abundances, and trafficking dynamics of Nav1.2 and Nav1.6 in cultured mouse and rat neurons and in male and female mouse brain. We discovered a previously uncharacterized trafficking pathway that targets Nav1.2 to the distal axon of unmyelinated neurons. This pathway uses distinct signals residing in the intracellular loop 1 between transmembrane domain I and II to suppress the retention of Nav1.2 in the axon initial segment and facilitate its membrane loading at the distal axon. As mouse pyramidal neurons undergo myelination, Nav1.2 is gradually excluded from the distal axon as Nav1.6 becomes the dominant VGSC in the axon initial segment and nodes of Ranvier. In addition, we revealed exquisite developmental regulation of Nav1.2 and Nav1.6 localizations in the axon initial segment and dendrites, clarifying the molecular identity of sodium channels in these subcellular compartments. Together, these results unveiled compartment-specific localizations and trafficking mechanisms for VGSCs, which could be regulated separately to modulate membrane excitability in the brain.SIGNIFICANCE STATEMENT Direct observation of endogenous voltage-gated sodium channels reveals a previously uncharacterized distal axon targeting mechanism and the molecular identity of sodium channels in distinct subcellular compartments.
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Affiliation(s)
- Hui Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147
| | - Hong-Gang Wang
- Weill Cornell Medicine, Cardiovascular Research Institute, New York, New York 10021
| | - Geoffrey Pitt
- Weill Cornell Medicine, Cardiovascular Research Institute, New York, New York 10021
| | - Zhe Liu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia 20147
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19
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Park C, Jung S, Park H. Single vesicle tracking for studying synaptic vesicle dynamics in small central synapses. Curr Opin Neurobiol 2022; 76:102596. [PMID: 35803103 DOI: 10.1016/j.conb.2022.102596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/20/2022] [Accepted: 05/27/2022] [Indexed: 11/26/2022]
Abstract
Sustained neurotransmission is driven by a continuous supply of synaptic vesicles to the release sites and modulated by synaptic vesicle dynamics. However, synaptic vesicle dynamics in synapses remain elusive because of technical limitations. Recent advances in fluorescence imaging techniques have enabled the tracking of single synaptic vesicles in small central synapses in living neurons. Single vesicle tracking has uncovered a wealth of new information about synaptic vesicle dynamics both within and outside presynaptic terminals, showing that single vesicle tracking is an effective tool for studying synaptic vesicle dynamics. Particularly, single vesicle tracking with high spatiotemporal resolution has revealed the dependence of synaptic vesicle dynamics on the location, stages of recycling, and neuronal activity. This review summarizes the recent findings from single synaptic vesicle tracking in small central synapses and their implications in synaptic transmission and pathogenic mechanisms of neurodegenerative diseases.
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Affiliation(s)
- Chungwon Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong
| | - Sangyong Jung
- Institute of Molecular and Cell Biology (IMCB), Agency for Science, Technology and Research (A∗STAR), 11 Biopolis Way, 138667, Singapore; Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, 119077, Singapore
| | - Hyokeun Park
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong; State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, 999077, Hong Kong.
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20
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Kinetic principles underlying pioneer function of GAGA transcription factor in live cells. Nat Struct Mol Biol 2022; 29:665-676. [PMID: 35835866 PMCID: PMC10177624 DOI: 10.1038/s41594-022-00800-z] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 05/27/2022] [Indexed: 11/09/2022]
Abstract
How pioneer factors interface with chromatin to promote accessibility for transcription control is poorly understood in vivo. Here, we directly visualize chromatin association by the prototypical GAGA pioneer factor (GAF) in live Drosophila hemocytes. Single-particle tracking reveals that most GAF is chromatin bound, with a stable-binding fraction showing nucleosome-like confinement residing on chromatin for more than 2 min, far longer than the dynamic range of most transcription factors. These kinetic properties require the full complement of GAF's DNA-binding, multimerization and intrinsically disordered domains, and are autonomous from recruited chromatin remodelers NURF and PBAP, whose activities primarily benefit GAF's neighbors such as Heat Shock Factor. Evaluation of GAF kinetics together with its endogenous abundance indicates that, despite on-off dynamics, GAF constitutively and fully occupies major chromatin targets, thereby providing a temporal mechanism that sustains open chromatin for transcriptional responses to homeostatic, environmental and developmental signals.
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21
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Gormal RS, Meunier FA. Nanoscale organization of the pre-synapse: Tracking the neurotransmitter release machinery. Curr Opin Neurobiol 2022; 75:102576. [PMID: 35716557 DOI: 10.1016/j.conb.2022.102576] [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: 02/16/2022] [Revised: 05/02/2022] [Accepted: 05/11/2022] [Indexed: 11/18/2022]
Abstract
Chemical communication is underpinned by the fusion of neurotransmitter-containing synaptic vesicles with the plasma membrane at active zones. With the advent of super-resolution microscopy, the door is now opened to unravel the dynamic remodeling of synapses underpinning learning and memory. Imaging proteins with conventional light microscopy cannot provide submicron information vital to determining the nanoscale organization of the synapse. We will first review the current super-resolution microscopy techniques available to investigate the localization and movement of synaptic proteins and how they have been applied to visualize the synapse. We discuss the new techniques and analytical approaches have provided comprehensive insights into synaptic organization in various model systems. Finally, this review provides a brief update on how these super-resolution techniques and analyses have opened the way to a much greater understanding of the synapse, the fusion and compensatory endocytosis machinery.
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Affiliation(s)
- Rachel S Gormal
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, 4072, Australia. https://twitter.com/rachelgormal
| | - Frédéric A Meunier
- Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, 4072, Australia.
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22
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Interplay between regulatory elements and chromatin topology in cellular lineage determination. Trends Genet 2022; 38:1048-1061. [DOI: 10.1016/j.tig.2022.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 05/02/2022] [Accepted: 05/12/2022] [Indexed: 11/16/2022]
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23
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Zhang Y, Lu Y, El Sayyed H, Bian J, Lin J, Li X. Transcription factor dynamics in plants: Insights and technologies for in vivo imaging. PLANT PHYSIOLOGY 2022; 189:23-36. [PMID: 35134239 PMCID: PMC9070795 DOI: 10.1093/plphys/kiac042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
Biochemical and genetic approaches have been extensively used to study transcription factor (TF) functions, but their dynamic behaviors and the complex ways in which they regulate transcription in plant cells remain unexplored, particularly behaviors such as translocation and binding to DNA. Recent developments in labeling and imaging techniques provide the necessary sensitivity and resolution to study these behaviors in living cells. In this review, we present an up-to-date portrait of the dynamics and regulation of TFs under physiologically relevant conditions and then summarize recent advances in fluorescent labeling strategies and imaging techniques. We then discuss future prospects and challenges associated with the application of these techniques to examine TFs' intricate dance in living plants.
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Affiliation(s)
- Yuan Zhang
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants Ministry of Education, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
| | - Yuqing Lu
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants Ministry of Education, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
| | - Hafez El Sayyed
- Department of Physics, University of Oxford, Oxford OX1 3PU, UK
| | - Jiahui Bian
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants Ministry of Education, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
| | - Jinxing Lin
- Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants Ministry of Education, College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing 100083, China
- Beijing Advanced Innovation Center for Tree Breeding by Molecular Design, Beijing Forestry University, Beijing 100083, China
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24
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Eichel K, Shen K. The function of the axon initial segment in neuronal polarity. Dev Biol 2022; 489:47-54. [DOI: 10.1016/j.ydbio.2022.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2021] [Revised: 05/09/2022] [Accepted: 05/23/2022] [Indexed: 11/25/2022]
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25
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Quantifying the global binding and target-search dynamics of epigenetic regulatory factors using live-cell single-molecule tracking. STAR Protoc 2021; 2:100959. [PMID: 34825219 PMCID: PMC8605088 DOI: 10.1016/j.xpro.2021.100959] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
This protocol provides instructions to track the global dynamics of single epigenetic regulatory factors in live cells. We describe an approach to generate cell lines that stably express HaloTag-fused proteins. We then use live-cell single-molecule tracking to obtain kinetic populations and residence times. The kinetic parameters obtained can be used to determine important aspects of transcriptional regulation such as target-search time, 3D free diffusion time, and number of non-specific sites sampled before reaching a specific site and compare behaviors across different nuclear environments. For complete details on the use and execution of this protocol, please refer to Kent et al. (2020). Generate cell lines stably expressing HaloTag fusion genes Quantify global binding and target-search kinetics of epigenetic factors Map binding dynamics of epigenetic factors within transcriptional condensates
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26
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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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27
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Li C, Lai C, Peng F, Xue X, You Q, Liu F, Guo P, Liao J, Wang T. Dominant Plant Functional Group Determine the Response of the Temporal Stability of Plant Community Biomass to 9-Year Warming on the Qinghai-Tibetan Plateau. FRONTIERS IN PLANT SCIENCE 2021; 12:704138. [PMID: 34539698 PMCID: PMC8446532 DOI: 10.3389/fpls.2021.704138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 08/09/2021] [Indexed: 05/24/2023]
Abstract
Ecosystem stability characterizes ecosystem responses to natural and anthropogenic disturbance and affects the feedback between ecosystem and climate. A 9-year warming experiment (2010-2018) was conducted to examine how climatic warming and its interaction with the soil moisture condition impact the temporal stability of plant community aboveground biomass (AGB) of an alpine meadow in the central Qinghai-Tibetan Plateau (QTP). Under a warming environment, the AGB percentage of grasses and forbs significantly increased but that of sedges decreased regardless of the soil water availability in the experimental plots. The warming effects on plant AGB varied with annual precipitation. In the dry condition, the AGB showed no significant change under warming in the normal and relatively wet years, but it significantly decreased in relatively drought years (16% in 2013 and 12% in 2015). In the wet condition, the AGB showed no significant change under warming in the normal and relatively drought years, while it significantly increased in relatively wet years (12% in 2018). Warming significantly decreased the temporal stability of AGB of plant community and sedges. Species richness remained stable even under the warming treatment in both the dry and wet conditions. The temporal stability of AGB of sedges (dominant plant functional group) explained 66.69% variance of the temporal stability of plant community AGB. Our findings highlight that the temporal stability of plant community AGB is largely regulated by the dominant plant functional group of alpine meadow that has a relatively low species diversity.
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Affiliation(s)
- Chengyang Li
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Chimin Lai
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
| | - Fei Peng
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- Arid Land Research Center, Tottori University, Tottori, Japan
- Beiluhe Observation and Research Station of Frozen Soil Engineering and Environment, State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- Drylands Salinization Research Station, Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Xian Xue
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- Drylands Salinization Research Station, Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Quangang You
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- Drylands Salinization Research Station, Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Feiyao Liu
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
- Drylands Salinization Research Station, Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Pinglin Guo
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
- College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, China
- Drylands Salinization Research Station, Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Jie Liao
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
| | - Tao Wang
- Key Laboratory of Desert and Desertification, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences (CAS), Lanzhou, China
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28
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Mazzocca M, Colombo E, Callegari A, Mazza D. Transcription factor binding kinetics and transcriptional bursting: What do we really know? Curr Opin Struct Biol 2021; 71:239-248. [PMID: 34481381 DOI: 10.1016/j.sbi.2021.08.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 11/18/2022]
Abstract
In eukaryotes, transcription is a discontinuous process with mRNA being generated in bursts, after the binding of transcription factors (TFs) to regulatory elements on the genome. Live-cell single-molecule microscopy has highlighted that transcriptional bursting can be controlled by tuning TF/DNA binding kinetics. Yet the timescales of these two processes seem disconnected with TF/DNA interactions typically lasting orders of magnitude shorter than transcriptional bursts. To test models that could reconcile these discrepancies, reliable measurements of TF binding kinetics are needed, also accounting for the current limitations in performing these single-molecule measurements at specific regulatory elements. Here, we review the recent studies linking TF binding kinetics to transcriptional bursting and outline some current and future challenges that need to be addressed to provide a microscopic description of transcriptional regulation kinetics.
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Affiliation(s)
- Matteo Mazzocca
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Emanuele Colombo
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | | | - Davide Mazza
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy.
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29
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Garcia DA, Fettweis G, Presman DM, Paakinaho V, Jarzynski C, Upadhyaya A, Hager GL. Power-law behavior of transcription factor dynamics at the single-molecule level implies a continuum affinity model. Nucleic Acids Res 2021; 49:6605-6620. [PMID: 33592625 DOI: 10.1093/nar/gkab072] [Citation(s) in RCA: 58] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 01/13/2021] [Accepted: 02/11/2021] [Indexed: 12/11/2022] Open
Abstract
Single-molecule tracking (SMT) allows the study of transcription factor (TF) dynamics in the nucleus, giving important information regarding the diffusion and binding behavior of these proteins in the nuclear environment. Dwell time distributions obtained by SMT for most TFs appear to follow bi-exponential behavior. This has been ascribed to two discrete populations of TFs-one non-specifically bound to chromatin and another specifically bound to target sites, as implied by decades of biochemical studies. However, emerging studies suggest alternate models for dwell-time distributions, indicating the existence of more than two populations of TFs (multi-exponential distribution), or even the absence of discrete states altogether (power-law distribution). Here, we present an analytical pipeline to evaluate which model best explains SMT data. We find that a broad spectrum of TFs (including glucocorticoid receptor, oestrogen receptor, FOXA1, CTCF) follow a power-law distribution of dwell-times, blurring the temporal line between non-specific and specific binding, suggesting that productive binding may involve longer binding events than previously believed. From these observations, we propose a continuum of affinities model to explain TF dynamics, that is consistent with complex interactions of TFs with multiple nuclear domains as well as binding and searching on the chromatin template.
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Affiliation(s)
- David A Garcia
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20893, USA.,Department of Physics, University of Maryland, College Park, MD 20742, USA
| | - Gregory Fettweis
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20893, USA
| | - Diego M Presman
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20893, USA.,Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EGA, Buenos Aires, Argentina
| | - Ville Paakinaho
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20893, USA.,Institute of Biomedicine, University of Eastern Finland, Kuopio, PO Box 1627, FI-70211 Kuopio, Finland
| | - Christopher Jarzynski
- Department of Physics, University of Maryland, College Park, MD 20742, USA.,Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Arpita Upadhyaya
- Department of Physics, University of Maryland, College Park, MD 20742, USA.,Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20893, USA
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30
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Brown K, Andrianakos H, Ingersoll S, Ren X. Single-molecule imaging of epigenetic complexes in living cells: insights from studies on Polycomb group proteins. Nucleic Acids Res 2021; 49:6621-6637. [PMID: 34009336 PMCID: PMC8266577 DOI: 10.1093/nar/gkab304] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 04/09/2021] [Accepted: 04/13/2021] [Indexed: 12/30/2022] Open
Abstract
Chromatin-associated factors must locate, bind to, and assemble on specific chromatin regions to execute chromatin-templated functions. These dynamic processes are essential for understanding how chromatin achieves regulation, but direct quantification in living mammalian cells remains challenging. Over the last few years, live-cell single-molecule tracking (SMT) has emerged as a new way to observe trajectories of individual chromatin-associated factors in living mammalian cells, providing new perspectives on chromatin-templated activities. Here, we discuss the relative merits of live-cell SMT techniques currently in use. We provide new insights into how Polycomb group (PcG) proteins, master regulators of development and cell differentiation, decipher genetic and epigenetic information to achieve binding stability and highlight that Polycomb condensates facilitate target-search efficiency. We provide perspectives on liquid-liquid phase separation in organizing Polycomb targets. We suggest that epigenetic complexes integrate genetic and epigenetic information for target binding and localization and achieve target-search efficiency through nuclear organization.
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Affiliation(s)
- Kyle Brown
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | | | - Steven Ingersoll
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, CO 80217-3364, USA
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31
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Xie L, Liu Z. Single-cell imaging of genome organization and dynamics. Mol Syst Biol 2021; 17:e9653. [PMID: 34232558 PMCID: PMC8262488 DOI: 10.15252/msb.20209653] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 04/13/2021] [Accepted: 04/23/2021] [Indexed: 12/28/2022] Open
Abstract
Probing the architecture, mechanism, and dynamics of genome folding is fundamental to our understanding of genome function in homeostasis and disease. Most chromosome conformation capture studies dissect the genome architecture with population- and time-averaged snapshots and thus have limited capabilities to reveal 3D nuclear organization and dynamics at the single-cell level. Here, we discuss emerging imaging techniques ranging from light microscopy to electron microscopy that enable investigation of genome folding and dynamics at high spatial and temporal resolution. Results from these studies complement genomic data, unveiling principles underlying the spatial arrangement of the genome and its potential functional links to diverse biological activities in the nucleus.
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Affiliation(s)
- Liangqi Xie
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
| | - Zhe Liu
- Janelia Research CampusHoward Hughes Medical InstituteAshburnVAUSA
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32
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Mazzocca M, Fillot T, Loffreda A, Gnani D, Mazza D. The needle and the haystack: single molecule tracking to probe the transcription factor search in eukaryotes. Biochem Soc Trans 2021; 49:1121-1132. [PMID: 34003257 PMCID: PMC8286828 DOI: 10.1042/bst20200709] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 04/18/2021] [Accepted: 04/19/2021] [Indexed: 12/13/2022]
Abstract
Transcription factors (TFs) regulate transcription of their target genes by identifying and binding to regulatory regions of the genome among billions of potential non-specific decoy sites, a task that is often presented as a 'needle in the haystack' challenge. The TF search process is now well understood in bacteria, but its characterization in eukaryotes needs to account for the complex organization of the nuclear environment. Here we review how live-cell single molecule tracking is starting to shed light on the TF search mechanism in the eukaryotic cell and we outline the future challenges to tackle in order to understand how nuclear organization modulates the TF search process in physiological and pathological conditions.
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Affiliation(s)
- Matteo Mazzocca
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Tom Fillot
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Alessia Loffreda
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Daniela Gnani
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Davide Mazza
- Experimental Imaging Center, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
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33
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Hoboth P, Šebesta O, Hozák P. How Single-Molecule Localization Microscopy Expanded Our Mechanistic Understanding of RNA Polymerase II Transcription. Int J Mol Sci 2021; 22:6694. [PMID: 34206594 PMCID: PMC8269275 DOI: 10.3390/ijms22136694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 06/17/2021] [Accepted: 06/19/2021] [Indexed: 11/16/2022] Open
Abstract
Classical models of gene expression were built using genetics and biochemistry. Although these approaches are powerful, they have very limited consideration of the spatial and temporal organization of gene expression. Although the spatial organization and dynamics of RNA polymerase II (RNAPII) transcription machinery have fundamental functional consequences for gene expression, its detailed studies have been abrogated by the limits of classical light microscopy for a long time. The advent of super-resolution microscopy (SRM) techniques allowed for the visualization of the RNAPII transcription machinery with nanometer resolution and millisecond precision. In this review, we summarize the recent methodological advances in SRM, focus on its application for studies of the nanoscale organization in space and time of RNAPII transcription, and discuss its consequences for the mechanistic understanding of gene expression.
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Affiliation(s)
- Peter Hoboth
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic;
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic;
| | - Ondřej Šebesta
- Faculty of Science, Charles University, Albertov 6, 128 00 Prague, Czech Republic;
| | - Pavel Hozák
- Department of Biology of the Cell Nucleus, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic;
- Microscopy Centre, Institute of Molecular Genetics of the Czech Academy of Sciences, Vídeňská 1083, 142 20 Prague, Czech Republic
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34
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Makhija S, Brown D, Rudlaff RM, Doh JK, Bourke S, Wang Y, Zhou S, Cheloor-Kovilakam R, Huang B. Versatile Labeling and Detection of Endogenous Proteins Using Tag-Assisted Split Enzyme Complementation. ACS Chem Biol 2021; 16:671-681. [PMID: 33734687 DOI: 10.1021/acschembio.0c00925] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Recent advances in genome engineering have expanded our capabilities to study proteins in their natural states. In particular, the ease and scalability of knocking-in small peptide tags has enabled high throughput tagging and analysis of endogenous proteins. To improve enrichment capacities and expand the functionality of knock-ins using short tags, we developed the tag-assisted split enzyme complementation (TASEC) approach, which uses two orthogonal small peptide tags and their cognate binders to conditionally drive complementation of a split enzyme upon labeled protein expression. Using this approach, we have engineered and optimized the tag-assisted split HaloTag complementation system (TA-splitHalo) and demonstrated its versatile applications in improving the efficiency of knock-in cell enrichment, detection of protein-protein interaction, and isolation of biallelic gene edited cells through multiplexing.
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Affiliation(s)
- Suraj Makhija
- UC Berkeley - UCSF Joint Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, California 94143, United States
| | - David Brown
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Rachel M. Rudlaff
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Julia K. Doh
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Struan Bourke
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Yina Wang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Shuqin Zhou
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California 94143, United States
- School of Pharmacy, Tsinghua University, Beijing 100872, China
| | - Rasmi Cheloor-Kovilakam
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
| | - Bo Huang
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94143, United States
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94143, United States
- Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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35
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Shao S, Zhang H, Zeng Y, Li Y, Sun C, Sun Y. TagBiFC technique allows long-term single-molecule tracking of protein-protein interactions in living cells. Commun Biol 2021; 4:378. [PMID: 33742089 PMCID: PMC7979928 DOI: 10.1038/s42003-021-01896-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 02/12/2021] [Indexed: 01/09/2023] Open
Abstract
Protein-protein interactions (PPIs) are critical for cellular activity regulation. Visualization of PPIs using bimolecular fluorescence complementation (BiFC) techniques helps to understand how PPIs implement their functions. However, current BiFC is based on fluorescent proteins and the brightness and photostability are suboptimal for single molecule tracking experiments, resulting in either low spatiotemporal resolution or incapability of tracking for extended time course. Here, we developed the TagBiFC technique based on split HaloTag, a self-labeling tag that could conjugate an organic dye molecule and thus offered better brightness and photostability than fluorescent proteins for PPI visualization inside living cells. Through screening and optimization, we demonstrated that the reconstituted HaloTag exhibited higher localization precision and longer tracking length than previous methods. Using TagBiFC, we reveal that the dynamic interactions of transcription factor dimers with chromatin DNA are distinct and closely related to their dimeric states, indicating a general regulatory mechanism for these kinds of transcription factors. In addition, we also demonstrated the advantageous applications of TagBiFC in single nucleosome imaging, light-burden imaging of single mRNA, low background imaging of cellular structures. We believe these superior properties of our TagBiFC system will have broad applications in the studies of single molecule imaging inside living cells.
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Affiliation(s)
- Shipeng Shao
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.,Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Hongchen Zhang
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Yong Zeng
- Beijing Institute of Heart Lung and Blood Vessel Disease, Beijing Anzhen Hospital, Capital Medical University, Beijing, China
| | - Yongliang Li
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.,The Second Dental Center, Peking University School and Hospital of Stomatology, Beijing, China
| | - Chaoying Sun
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China
| | - Yujie Sun
- State Key Laboratory of Membrane Biology, Biomedical Pioneering Innovation Center (BIOPIC), School of Life Sciences, Peking University, Beijing, China.
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36
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Chu JM, Pease NA, Kueh HY. In search of lost time: Enhancers as modulators of timing in lymphocyte development and differentiation. Immunol Rev 2021; 300:134-151. [PMID: 33734444 PMCID: PMC8005465 DOI: 10.1111/imr.12946] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 12/15/2020] [Accepted: 12/23/2020] [Indexed: 12/21/2022]
Abstract
Proper timing of gene expression is central to lymphocyte development and differentiation. Lymphocytes often delay gene activation for hours to days after the onset of signaling components, which act on the order of seconds to minutes. Such delays play a prominent role during the intricate choreography of developmental events and during the execution of an effector response. Though a number of mechanisms are sufficient to explain timing at short timescales, it is not known how timing delays are implemented over long timescales that may span several cell generations. Based on the literature, we propose that a class of cis-regulatory elements, termed "timing enhancers," may explain how timing delays are controlled over these long timescales. By considering chromatin as a kinetic barrier to state switching, the timing enhancer model explains experimentally observed dynamics of gene expression where other models fall short. In this review, we elaborate on features of the timing enhancer model and discuss the evidence for its generality throughout development and differentiation. We then discuss potential molecular mechanisms underlying timing enhancer function. Finally, we explore recent evidence drawing connections between timing enhancers and genetic risk for immunopathology. We argue that the timing enhancer model is a useful framework for understanding how cis-regulatory elements control the central dimension of timing in lymphocyte biology.
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Affiliation(s)
- Jonathan M Chu
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, Seattle, WA, USA
| | - Nicholas A Pease
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, Seattle, WA, USA
| | - Hao Yuan Kueh
- Department of Bioengineering, University of Washington, Seattle, WA, USA
- Institute for Stem Cell and Regenerative Medicine, Seattle, WA, USA
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37
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Bailey MLP, Yan H, Surovtsev I, Williams JF, King MC, Mochrie SGJ. Covariance distributions in single particle tracking. Phys Rev E 2021; 103:032405. [PMID: 33862686 PMCID: PMC9115892 DOI: 10.1103/physreve.103.032405] [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: 10/07/2020] [Accepted: 01/12/2021] [Indexed: 11/07/2022]
Abstract
Several recent experiments, including our own experiments in the fission yeast, Schizosaccharomyces pombe, have characterized the motions of gene loci within living nuclei by measuring the locus position over time, then proceeding to obtain the statistical properties of this motion. To address the question of whether a population of such single-particle tracks, obtained from many different cells, corresponds to a single mode of diffusion, we derive theoretical equations describing the probability distribution of the displacement covariance, assuming the displacement itself is a zero-mean multivariate Gaussian random variable. We also determine the corresponding theoretical means, variances, and third central moments. Bolstering the theory is good agreement between its predictions and the results obtained for various simulated and measured data sets, including simulated particle trajectories undergoing simple and anomalous diffusion, and the measured trajectories of an optically trapped bead in water, and in a viscoelastic polymer solution. We also show that, for sufficiently long tracks, each covariance distribution in all of these examples is well-described by a skew-normal distribution with mean, variance, and skewness given by the theory. However, for the experimentally measured motion of a gene locus in S. pombe, we find that the first two covariance distributions are wider than predicted, although the third and subsequent covariance distributions are well-described by theory. This observation suggests that the origin of the theory-experiment discrepancy in this case is associated with localization noise, which influences only the first two covariances. Thus, we hypothesized that the discrepancy is caused by locus-to-locus heterogeneity in the localization noise, of independent measurements of the same tagged site. Indeed, simulations implementing heterogeneous localization noise revealed that the excess covariance widths can be largely recreated on the basis of heterogeneous noise. Thus, we conclude that the motion of gene loci in fission yeast is consistent with a single mode of diffusion.
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Affiliation(s)
- Mary Lou P. Bailey
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Hao Yan
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
| | - Ivan Surovtsev
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Jessica F. Williams
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Megan C. King
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut 06520, USA
| | - Simon G. J. Mochrie
- Integrated Graduate Program in Physical and Engineering Biology, Yale University, New Haven, Connecticut 06520, USA
- Department of Applied Physics, Yale University, New Haven, Connecticut 06520, USA
- Department of Physics, Yale University, New Haven, Connecticut 06520, USA
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38
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Single-particle tracking photoactivated localization microscopy of membrane proteins in living plant tissues. Nat Protoc 2021; 16:1600-1628. [PMID: 33627844 DOI: 10.1038/s41596-020-00471-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/24/2020] [Indexed: 01/31/2023]
Abstract
Super-resolution microscopy techniques have pushed the limit of optical imaging to unprecedented spatial resolutions. However, one of the frontiers in nanoscopy is its application to intact living organisms. Here we describe the implementation and application of super-resolution single-particle tracking photoactivated localization microscopy (sptPALM) to probe single-molecule dynamics of membrane proteins in live roots of the model plant Arabidopsis thaliana. We first discuss the advantages and limitations of sptPALM for studying the diffusion properties of membrane proteins and compare this to fluorescence recovery after photobleaching (FRAP) and fluorescence correlation spectroscopy (FCS). We describe the technical details for handling and imaging the samples for sptPALM, with a particular emphasis on the specificity of imaging plant cells, such as their thick cell walls or high degree of autofluorescence. We then provide a practical guide from data collection to image analyses. In particular, we introduce our sptPALM_viewer software and describe how to install and use it for analyzing sptPALM experiments. Finally, we report an R statistical analysis pipeline to analyze and compare sptPALM experiments. Altogether, this protocol should enable plant researchers to perform sptPALM using a benchmarked reproducible protocol. Routinely, the procedure takes 3-4 h of imaging followed by 3-4 d of image processing and data analysis.
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39
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Kefer P, Iqbal F, Locatelli M, Lawrimore J, Zhang M, Bloom K, Bonin K, Vidi PA, Liu J. Performance of deep learning restoration methods for the extraction of particle dynamics in noisy microscopy image sequences. Mol Biol Cell 2021; 32:903-914. [PMID: 33502895 PMCID: PMC8108534 DOI: 10.1091/mbc.e20-11-0689] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Particle tracking in living systems requires low light exposure and short exposure times to avoid phototoxicity and photobleaching and to fully capture particle motion with high-speed imaging. Low-excitation light comes at the expense of tracking accuracy. Image restoration methods based on deep learning dramatically improve the signal-to-noise ratio in low-exposure data sets, qualitatively improving the images. However, it is not clear whether images generated by these methods yield accurate quantitative measurements such as diffusion parameters in (single) particle tracking experiments. Here, we evaluate the performance of two popular deep learning denoising software packages for particle tracking, using synthetic data sets and movies of diffusing chromatin as biological examples. With synthetic data, both supervised and unsupervised deep learning restored particle motions with high accuracy in two-dimensional data sets, whereas artifacts were introduced by the denoisers in three-dimensional data sets. Experimentally, we found that, while both supervised and unsupervised approaches improved tracking results compared with the original noisy images, supervised learning generally outperformed the unsupervised approach. We find that nicer-looking image sequences are not synonymous with more precise tracking results and highlight that deep learning algorithms can produce deceiving artifacts with extremely noisy images. Finally, we address the challenge of selecting parameters to train convolutional neural networks by implementing a frugal Bayesian optimizer that rapidly explores multidimensional parameter spaces, identifying networks yielding optimal particle tracking accuracy. Our study provides quantitative outcome measures of image restoration using deep learning. We anticipate broad application of this approach to critically evaluate artificial intelligence solutions for quantitative microscopy.
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Affiliation(s)
- Paul Kefer
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109
| | - Fadil Iqbal
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
| | - Maelle Locatelli
- Department of Cancer Biology, Wake Forest School of Medicine, and
| | - Josh Lawrimore
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Mengdi Zhang
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202.,Department of Pharmacology, School of Pharmacy, Harbin Medical University, Harbin 150081, China
| | - Kerry Bloom
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Keith Bonin
- Department of Physics, Wake Forest University, Winston-Salem, NC 27109.,Comprehensive Cancer Center of Wake Forest University, Winston-Salem, NC 27157
| | - Pierre-Alexandre Vidi
- Department of Cancer Biology, Wake Forest School of Medicine, and.,Comprehensive Cancer Center of Wake Forest University, Winston-Salem, NC 27157
| | - Jing Liu
- Department of Physics, Indiana University-Purdue University Indianapolis, Indianapolis, IN 46202
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Supra-Molecular Assemblies of ORAI1 at Rest Precede Local Accumulation into Puncta after Activation. Int J Mol Sci 2021; 22:ijms22020799. [PMID: 33466866 PMCID: PMC7831003 DOI: 10.3390/ijms22020799] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 01/04/2021] [Accepted: 01/12/2021] [Indexed: 12/13/2022] Open
Abstract
The Ca2+ selective channel ORAI1 and endoplasmic reticulum (ER)-resident STIM proteins form the core of the channel complex mediating store operated Ca2+ entry (SOCE). Using liquid phase electron microscopy (LPEM), the distribution of ORAI1 proteins was examined at rest and after SOCE-activation at nanoscale resolution. The analysis of over seven hundred thousand ORAI1 positions revealed a number of ORAI1 channels had formed STIM-independent distinct supra-molecular clusters. Upon SOCE activation and in the presence of STIM proteins, a fraction of ORAI1 assembled in micron-sized two-dimensional structures, such as the known puncta at the ER plasma membrane contact zones, but also in divergent structures such as strands, and ring-like shapes. Our results thus question the hypothesis that stochastically migrating single ORAI1 channels are trapped at regions containing activated STIM, and we propose instead that supra-molecular ORAI1 clusters fulfill an amplifying function for creating dense ORAI1 accumulations upon SOCE-activation.
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41
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Lerner J, Gómez-García PA, McCarthy RL, Liu Z, Lakadamyali M, Zaret KS. Two-parameter single-molecule analysis for measurement of chromatin mobility. STAR Protoc 2020; 1:100223. [PMID: 33377115 PMCID: PMC7757679 DOI: 10.1016/j.xpro.2020.100223] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
This protocol provides a two-parameter analysis of single-molecule tracking (SMT) trajectories of Halo-tagged histones in living adherent cell lines and unveils a chromatin mobility landscape composed of five chromatin types, ranging from low to high mobility. When the analysis is applied to Halo-tagged, chromatin-binding proteins, it associates chromatin interaction properties with known functions in a way that previously used SMT parameters did not. For complete information on the use and execution of this protocol, please refer to Lerner et al. (2020). Single-molecule imaging to assay/compare motions of chromatin and nuclear factors Protocol walks the user through imaging, detection, and tracking of single molecules Two-parameter analysis allows assay of motions of chromatin-interacting molecules Translates motions into interaction with functionally diverse chromatin domains
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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
| | - Pablo Aurelio Gómez-García
- Centre for Genomic Regulation (CRG), Barcelona Biomedical Research Park, 08003 Barcelona, Spain.,The Institute of Photonics Sciences (ICFO), Barcelona Institute of Science and Technology (BIST), 08003 Barcelona, Spain
| | - Ryan L McCarthy
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Zhe Liu
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - Melike Lakadamyali
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.,University of Pennsylvania, Department of Physiology, 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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Hsieh A, Pitarresi JR, Lerner J, Donahue G, Hsiehchen D, Rustgi AK, Zaret K. Growth of pancreatic cancers with hemizygous chromosomal 17p loss of MYBBP1A can be preferentially targeted by PARP inhibitors. SCIENCE ADVANCES 2020; 6:eabc4517. [PMID: 33277249 PMCID: PMC7821900 DOI: 10.1126/sciadv.abc4517] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 10/21/2020] [Indexed: 05/02/2023]
Abstract
Here, we selectively target pancreatic ductal adenocarcinoma (PDAC) cells harboring a hemizygous gene essential for cell growth. MYB binding protein 1A (MYBBP1A), encoding a chromatin-bound protein, is hemizygous in most of the PDAC due to a chromosome 17p deletion that also spans TP53 We find that hemizygous MYBBP1A loss in isogenic PDAC cells promotes tumorigenesis but, paradoxically, homozygous MYBBP1A loss is associated with impaired cell growth and decreased tumorigenesis. Poly-adenosine 5'-diphosphate-ribose polymerase 1 (PARP1) interacts with MYBBP1A and displaces it from chromatin. Small molecules, such as olaparib, that trap PARP1 to chromatin are able to evict the minimal pool of chromatin-bound MYBBP1A protein in MYBBP1A hemizygous cells and impair cell growth, greater than its impact on wild-type cells. Our findings reveal how a cell essential gene with one allele lost in cancer cells can be preferentially susceptible to a specific molecular therapy, when compared to wild-type cells.
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Affiliation(s)
- Antony Hsieh
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA
| | - Jason R Pitarresi
- Division of Gastroenterology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA
| | - Jonathan Lerner
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA
| | - Greg Donahue
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA
| | - David Hsiehchen
- Division of Hematology and Oncology, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Anil K Rustgi
- Herbert Irving Comprehensive Cancer Center, Columbia University College of Physicians and Surgeons, New York Presbyterian Hospital, New York City, NY 10032, USA
| | - Kenneth Zaret
- Institute for Regenerative Medicine, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania , Philadelphia, PA 19104-5157, USA.
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Modular transient nanoclustering of activated β2-adrenergic receptors revealed by single-molecule tracking of conformation-specific nanobodies. Proc Natl Acad Sci U S A 2020; 117:30476-30487. [PMID: 33214152 DOI: 10.1073/pnas.2007443117] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
None of the current superresolution microscopy techniques can reliably image the changes in endogenous protein nanoclustering dynamics associated with specific conformations in live cells. Single-domain nanobodies have been invaluable tools to isolate defined conformational states of proteins, and we reasoned that expressing these nanobodies coupled to single-molecule imaging-amenable tags could allow superresolution analysis of endogenous proteins in discrete conformational states. Here, we used anti-GFP nanobodies tagged with photoconvertible mEos expressed as intrabodies, as a proof-of-concept to perform single-particle tracking on a range of GFP proteins expressed in live cells, neurons, and small organisms. We next expressed highly specialized nanobodies that target conformation-specific endogenous β2-adrenoreceptor (β2-AR) in neurosecretory cells, unveiling real-time mobility behaviors of activated and inactivated endogenous conformers during agonist treatment in living cells. We showed that activated β2-AR (Nb80) is highly immobile and organized in nanoclusters. The Gαs-GPCR complex detected with Nb37 displayed higher mobility with surprisingly similar nanoclustering dynamics to that of Nb80. Activated conformers are highly sensitive to dynamin inhibition, suggesting selective targeting for endocytosis. Inactivated β2-AR (Nb60) molecules are also largely immobile but relatively less sensitive to endocytic blockade. Expression of single-domain nanobodies therefore provides a unique opportunity to capture highly transient changes in the dynamic nanoscale organization of endogenous proteins.
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Shaban HA, Barth R, Bystricky K. Navigating the crowd: visualizing coordination between genome dynamics, structure, and transcription. Genome Biol 2020; 21:278. [PMID: 33203432 PMCID: PMC7670612 DOI: 10.1186/s13059-020-02185-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Accepted: 10/19/2020] [Indexed: 12/12/2022] Open
Abstract
The eukaryotic genome is hierarchically structured yet highly dynamic. Regulating transcription in this environment demands a high level of coordination to permit many proteins to interact with chromatin fiber at appropriate sites in a timely manner. We describe how recent advances in quantitative imaging techniques overcome caveats of sequencing-based methods (Hi-C and related) by enabling direct visualization of transcription factors and chromatin at high resolution, from single genes to the whole nucleus. We discuss the contribution of fluorescence imaging to deciphering the principles underlying this coordination within the crowded nuclear space in living cells and discuss challenges ahead.
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Affiliation(s)
- Haitham A Shaban
- Spectroscopy Department, Physics Division, National Research Centre, Dokki, Cairo, 12622, Egypt.
- Current Address: Institute of Bioengineering, Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Roman Barth
- Department of Bionanoscience, Delft University of Technology, 2628 CJ, Delft, The Netherlands
| | - Kerstin Bystricky
- Laboratoire de Biologie Moléculaire Eucaryote (LBME), Centre de Biologie Intégrative (CBI), CNRS, UPS, University of Toulouse, 31062, Toulouse, France.
- Institut Universitaire de France (IUF), Paris, France.
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Huang W, Dai J, Wang W, Li J, Feng C, Du J. Phenological changes in herbaceous plants in China's grasslands and their responses to climate change: a meta-analysis. INTERNATIONAL JOURNAL OF BIOMETEOROLOGY 2020; 64:1865-1876. [PMID: 32734424 DOI: 10.1007/s00484-020-01974-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 07/06/2020] [Accepted: 07/21/2020] [Indexed: 06/11/2023]
Abstract
Plant phenological events are sensitive indicators of climate change, and their change could markedly affect the structure and function of ecosystems. Previous studies have revealed the spatiotemporal variations in the phenological events of woody plants. However, limited studies have focused on the phenophases of herbaceous plants. In this study, by using a meta-analysis method, we extracted information about the phenological changes in herbaceous plants in China's grasslands from existing studies (including the period, station, species, phenophases, phenological trends, and climatic determinants) and analyzed the patterns manifested in the dataset. The results showed that the spring phenophases (e.g., first leaf date and first flowering date) of the herbaceous plants mainly advanced over the past 30 years, but a large difference existed across grassland types. The spring phenophases of forages (species from the Cyperaceae, Gramineae, and Leguminosae families) became earlier in the desert steppe and alpine steppe but showed no apparent trends in the alpine meadow and even became later in the meadow steppe and typical steppe. In most cases, the increase in spring temperatures and precipitation promoted the greening up of herbaceous plants, while sunshine duration was positively correlated with the green-up date of herbaceous plants. For the autumn phenophases, the proportions of the earlier and later trends were very close, but the trends varied among the grassland types. The leaf coloring dates of the forages were delayed in the meadow steppe and alpine steppe but showed no distinct pattern in the typical steppe or alpine meadow and even became earlier in the desert steppe. In most cases, the increase in growing season temperature led to an earlier leaf coloring date of the herbaceous plants, but the increase in the preseason precipitation delayed the leaf coloring date. Our results suggested that the phenophases of herbaceous plants have complicated responses to multiple environmental factors, which makes predicting future phenological changes difficult.
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Affiliation(s)
- Wenjie Huang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Junhu Dai
- Key Laboratory of Land Surface Pattern and Simulation, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China
| | - Wei Wang
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
| | - Junsheng Li
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China.
| | - Chunting Feng
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
| | - Jinhong Du
- State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing, 100012, China
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Abstract
Pioneer transcription factors have the intrinsic biochemical ability to scan partial DNA sequence motifs that are exposed on the surface of a nucleosome and thus access silent genes that are inaccessible to other transcription factors. Pioneer factors subsequently enable other transcription factors, nucleosome remodeling complexes, and histone modifiers to engage chromatin, thereby initiating the formation of an activating or repressive regulatory sequence. Thus, pioneer factors endow the competence for fate changes in embryonic development, are essential for cellular reprogramming, and rewire gene networks in cancer cells. Recent studies with reconstituted nucleosomes in vitro and chromatin binding in vivo reveal that pioneer factors can directly perturb nucleosome structure and chromatin accessibility in different ways. This review focuses on our current understanding of the mechanisms by which pioneer factors initiate gene network changes and will ultimately contribute to our ability to control cell fates at will.
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Affiliation(s)
- Kenneth S Zaret
- Institute for Regenerative Medicine, Epigenetics Institute, Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104-5157, USA;
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47
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Lerner J, Gomez-Garcia PA, McCarthy RL, Liu Z, Lakadamyali M, Zaret KS. Two-Parameter Mobility Assessments Discriminate Diverse Regulatory Factor Behaviors in Chromatin. Mol Cell 2020; 79:677-688.e6. [PMID: 32574554 DOI: 10.1016/j.molcel.2020.05.036] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Revised: 04/06/2020] [Accepted: 05/27/2020] [Indexed: 12/20/2022]
Abstract
Enzymatic probes of chromatin structure reveal accessible versus inaccessible chromatin states, while super-resolution microscopy reveals a continuum of chromatin compaction states. Characterizing histone H2B movements by single-molecule tracking (SMT), we resolved chromatin domains ranging from low to high mobility and displaying different subnuclear localizations patterns. Heterochromatin constituents correlated with the lowest mobility chromatin, whereas transcription factors varied widely with regard to their respective mobility with low- or high-mobility chromatin. Pioneer transcription factors, which bind nucleosomes, can access the low-mobility chromatin domains, whereas weak or non-nucleosome binding factors are excluded from the domains and enriched in higher mobility domains. Nonspecific DNA and nucleosome binding accounted for most of the low mobility of strong nucleosome interactor FOXA1. Our analysis shows how the parameters of the mobility of chromatin-bound factors, but not their diffusion behaviors or SMT-residence times within chromatin, distinguish functional characteristics of different chromatin-interacting proteins.
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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
| | - Pablo Aurelio Gomez-Garcia
- Center for Genomic Regulation, Barcelona Biomedical Research Park, 08003 Barcelona, Spain; ICFO-Institute of Photonics Sciences, Barcelona Institute of Science and Technology, Barcelona, Spain
| | - Ryan L McCarthy
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Zhe Liu
- HHMI Janelia Research Campus, Ashburn, VA 20147, USA
| | - Melike Lakadamyali
- Institute for Regenerative Medicine and Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; University of Pennsylvania, Department of Physiology, 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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48
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Stortz M, Pecci A, Presman DM, Levi V. Unraveling the molecular interactions involved in phase separation of glucocorticoid receptor. BMC Biol 2020; 18:59. [PMID: 32487073 PMCID: PMC7268505 DOI: 10.1186/s12915-020-00788-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Accepted: 05/05/2020] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Functional compartmentalization has emerged as an important factor modulating the kinetics and specificity of biochemical reactions in the nucleus, including those involved in transcriptional regulation. The glucocorticoid receptor (GR) is a ligand-activated transcription factor that translocates to the nucleus upon hormone stimulation and distributes between the nucleoplasm and membraneless compartments named nuclear foci. While a liquid-liquid phase separation process has been recently proposed to drive the formation of many nuclear compartments, the mechanisms governing the heterogeneous organization of GR in the nucleus and the functional relevance of foci formation remain elusive. RESULTS We dissected some of the molecular interactions involved in the formation of GR condensates and analyzed the GR structural determinants relevant to this process. We show that GR foci present properties consistent with those expected for biomolecular condensates formed by a liquid-liquid phase separation process in living human cells. Their formation requires an initial interaction of GR with certain chromatin regions at specific locations within the nucleus. Surprisingly, the intrinsically disordered region of GR is not essential for condensate formation, in contrast to many nuclear proteins that require disordered regions to phase separate, while the ligand-binding domain seems essential for that process. We finally show that GR condensates include Mediator, a protein complex involved in transcription regulation. CONCLUSIONS We show that GR foci have properties of liquid condensates and propose that active GR molecules interact with chromatin and recruit multivalent cofactors whose interactions with additional molecules lead to the formation of a focus. The biological relevance of the interactions occurring in GR condensates supports their involvement in transcription regulation.
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Affiliation(s)
- Martin Stortz
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EGA, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Fisiología, Biología Molecular y Celular, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Adali Pecci
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EGA, Buenos Aires, Argentina
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina
| | - Diego M Presman
- Instituto de Fisiología, Biología Molecular y Neurociencias (IFIBYNE), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EGA, Buenos Aires, Argentina.
| | - Valeria Levi
- Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), CONICET-Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, C1428EGA, Buenos Aires, Argentina.
- Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Universidad de Buenos Aires, C1428EGA, Buenos Aires, Argentina.
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Srivastava D, Mahony S. Sequence and chromatin determinants of transcription factor binding and the establishment of cell type-specific binding patterns. BIOCHIMICA ET BIOPHYSICA ACTA. GENE REGULATORY MECHANISMS 2020; 1863:194443. [PMID: 31639474 PMCID: PMC7166147 DOI: 10.1016/j.bbagrm.2019.194443] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 09/21/2019] [Accepted: 10/06/2019] [Indexed: 12/14/2022]
Abstract
Transcription factors (TFs) selectively bind distinct sets of sites in different cell types. Such cell type-specific binding specificity is expected to result from interplay between the TF's intrinsic sequence preferences, cooperative interactions with other regulatory proteins, and cell type-specific chromatin landscapes. Cell type-specific TF binding events are highly correlated with patterns of chromatin accessibility and active histone modifications in the same cell type. However, since concurrent chromatin may itself be a consequence of TF binding, chromatin landscapes measured prior to TF activation provide more useful insights into how cell type-specific TF binding events became established in the first place. Here, we review the various sequence and chromatin determinants of cell type-specific TF binding specificity. We identify the current challenges and opportunities associated with computational approaches to characterizing, imputing, and predicting cell type-specific TF binding patterns. We further focus on studies that characterize TF binding in dynamic regulatory settings, and we discuss how these studies are leading to a more complex and nuanced understanding of dynamic protein-DNA binding activities. We propose that TF binding activities at individual sites can be viewed along a two-dimensional continuum of local sequence and chromatin context. Under this view, cell type-specific TF binding activities may result from either strongly favorable sequence features or strongly favorable chromatin context.
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Affiliation(s)
- Divyanshi Srivastava
- Center for Eukaryotic Gene Regulation, Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America
| | - Shaun Mahony
- Center for Eukaryotic Gene Regulation, Department of Biochemistry & Molecular Biology, The Pennsylvania State University, University Park, PA, United States of America.
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50
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Shaban HA, Seeber A. Monitoring global chromatin dynamics in response to DNA damage. Mutat Res 2020; 821:111707. [PMID: 32505939 DOI: 10.1016/j.mrfmmm.2020.111707] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 05/08/2020] [Accepted: 05/16/2020] [Indexed: 02/08/2023]
Abstract
DNA damage induced global chromatin motion has been observed in yeast and mammalian cells. Currently, it is unclear what mechanisms may be driving these changes in whole genome dynamics. Recent advances in live-cell microscopy now enable chromatin motion to be quantified throughout the whole nucleus. In addition, much work has improved quantification of single particle trajectories. This topic is particularly important to the field of DNA repair as there are a large number of unanswered questions that can be tackled by monitoring global chromatin movement. Foremost, is how local DNA repair mechanisms interact and change global chromatin structure and whether this impacts repair pathway choice or efficiency. In this review, we describe methodologies to monitor global chromatin movement putting them into context with the DNA repair field highlighting how these techniques can drive new discoveries.
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Affiliation(s)
- Haitham A Shaban
- Center for Advanced Imaging, Harvard University, Cambridge, MA, 02138, USA; Spectroscopy Department, Physics Division, National Research Centre, Dokki, 12622 Cairo, Egypt
| | - Andrew Seeber
- Center for Advanced Imaging, Harvard University, Cambridge, MA, 02138, USA.
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