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Bohrer CH, Larson DR. Synthetic analysis of chromatin tracing and live-cell imaging indicates pervasive spatial coupling between genes. eLife 2023; 12:81861. [PMID: 36790144 PMCID: PMC9984193 DOI: 10.7554/elife.81861] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 02/10/2023] [Indexed: 02/16/2023] Open
Abstract
The role of the spatial organization of chromosomes in directing transcription remains an outstanding question in gene regulation. Here, we analyze two recent single-cell imaging methodologies applied across hundreds of genes to systematically analyze the contribution of chromosome conformation to transcriptional regulation. Those methodologies are (1) single-cell chromatin tracing with super-resolution imaging in fixed cells; and (2) high-throughput labeling and imaging of nascent RNA in living cells. Specifically, we determine the contribution of physical distance to the coordination of transcriptional bursts. We find that individual genes adopt a constrained conformation and reposition toward the centroid of the surrounding chromatin upon activation. Leveraging the variability in distance inherent in single-cell imaging, we show that physical distance - but not genomic distance - between genes on individual chromosomes is the major factor driving co-bursting. By combining this analysis with live-cell imaging, we arrive at a corrected transcriptional correlation of [Formula: see text] for genes separated by < 400 nm. We propose that this surprisingly large correlation represents a physical property of human chromosomes and establishes a benchmark for future experimental studies.
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Affiliation(s)
- Christopher H Bohrer
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesdaUnited States
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of HealthBethesdaUnited States
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Abstract
Mammalian genomes have distinct levels of spatial organization and structure that have been hypothesized to play important roles in transcription regulation. Although much has been learned about these architectural features with ensemble techniques, single-cell studies are showing a new universal trend: Genomes are stochastic and dynamic at every level of organization. Stochastic gene expression, on the other hand, has been studied for years. In this review, we probe whether there is a causative link between the two phenomena. We specifically discuss the functionality of chromatin state, topologically associating domains (TADs), and enhancer biology in light of their stochastic nature and their specific roles in stochastic gene expression. We highlight persistent fundamental questions in this area of research.
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Affiliation(s)
- Christopher H Bohrer
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | - Daniel R Larson
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Bohrer CH, Yang X, Thakur S, Weng X, Tenner B, McQuillen R, Ross B, Wooten M, Chen X, Zhang J, Roberts E, Lakadamyali M, Xiao J. A pairwise distance distribution correction (DDC) algorithm to eliminate blinking-caused artifacts in SMLM. Nat Methods 2021; 18:669-677. [PMID: 34059826 PMCID: PMC9040192 DOI: 10.1038/s41592-021-01154-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 04/12/2021] [Indexed: 02/04/2023]
Abstract
Single-molecule localization microscopy (SMLM) relies on the blinking behavior of a fluorophore, which is the stochastic switching between fluorescent and dark states. Blinking creates multiple localizations belonging to the same fluorophore, confounding quantitative analyses and interpretations. Here we present a method, termed distance distribution correction (DDC), to eliminate blinking-caused repeat localizations without any additional calibrations. The approach relies on obtaining the true pairwise distance distribution of different fluorophores naturally from the imaging sequence by using distances between localizations separated by a time much longer than the average fluorescence survival time. We show that, using the true pairwise distribution, we can define and maximize the likelihood, obtaining a set of localizations void of blinking artifacts. DDC results in drastic improvements in obtaining the closest estimate of the true spatial organization and number of fluorescent emitters in a wide range of applications, enabling accurate reconstruction and quantification of SMLM images.
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Affiliation(s)
- Christopher H. Bohrer
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA.,Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Shreyasi Thakur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xiaoli Weng
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Brian Tenner
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Ryan McQuillen
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Brian Ross
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Matthew Wooten
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Xin Chen
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Elijah Roberts
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Melike Lakadamyali
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
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Bohrer CH, Yang X, Thakur S, Weng X, Tenner B, McQuillen R, Ross B, Wooten M, Chen X, Zhang J, Roberts E, Lakadamyali M, Xiao J. A pairwise distance distribution correction (DDC) algorithm to eliminate blinking-caused artifacts in SMLM. Nat Methods 2021. [PMID: 34059826 DOI: 10.1101/768051] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Single-molecule localization microscopy (SMLM) relies on the blinking behavior of a fluorophore, which is the stochastic switching between fluorescent and dark states. Blinking creates multiple localizations belonging to the same fluorophore, confounding quantitative analyses and interpretations. Here we present a method, termed distance distribution correction (DDC), to eliminate blinking-caused repeat localizations without any additional calibrations. The approach relies on obtaining the true pairwise distance distribution of different fluorophores naturally from the imaging sequence by using distances between localizations separated by a time much longer than the average fluorescence survival time. We show that, using the true pairwise distribution, we can define and maximize the likelihood, obtaining a set of localizations void of blinking artifacts. DDC results in drastic improvements in obtaining the closest estimate of the true spatial organization and number of fluorescent emitters in a wide range of applications, enabling accurate reconstruction and quantification of SMLM images.
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Affiliation(s)
- Christopher H Bohrer
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Xinxing Yang
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Shreyasi Thakur
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Xiaoli Weng
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Brian Tenner
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Ryan McQuillen
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA
| | - Brian Ross
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Matthew Wooten
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Xin Chen
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA
| | - Jin Zhang
- Department of Pharmacology, University of California San Diego, San Diego, CA, USA
| | - Elijah Roberts
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA
| | - Melike Lakadamyali
- Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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Theoni Gyparaki M, Arab A, Sorokina EM, Santiago-Ruiz AN, Bohrer CH, Xiao J, Lakadamyali M. Tau Forms Oligomeric Complexes on Microtubules that are Distinct from Pathological Oligomers in Disease. Biophys J 2021. [DOI: 10.1016/j.bpj.2020.11.442] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Tenner B, Getz M, Ross B, Ohadi D, Bohrer CH, Greenwald E, Mehta S, Xiao J, Rangamani P, Zhang J. Spatially compartmentalized phase regulation of a Ca 2+-cAMP-PKA oscillatory circuit. eLife 2020; 9:e55013. [PMID: 33201801 PMCID: PMC7671691 DOI: 10.7554/elife.55013] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 10/07/2020] [Indexed: 01/31/2023] Open
Abstract
Signaling networks are spatiotemporally organized to sense diverse inputs, process information, and carry out specific cellular tasks. In β cells, Ca2+, cyclic adenosine monophosphate (cAMP), and Protein Kinase A (PKA) exist in an oscillatory circuit characterized by a high degree of feedback. Here, we describe a mode of regulation within this circuit involving a spatial dependence of the relative phase between cAMP, PKA, and Ca2+. We show that in mouse MIN6 β cells, nanodomain clustering of Ca2+-sensitive adenylyl cyclases (ACs) drives oscillations of local cAMP levels to be precisely in-phase with Ca2+ oscillations, whereas Ca2+-sensitive phosphodiesterases maintain out-of-phase oscillations outside of the nanodomain. Disruption of this precise phase relationship perturbs Ca2+ oscillations, suggesting the relative phase within an oscillatory circuit can encode specific functional information. This work unveils a novel mechanism of cAMP compartmentation utilized for localized tuning of an oscillatory circuit and has broad implications for the spatiotemporal regulation of signaling networks.
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Affiliation(s)
- Brian Tenner
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of MedicineBaltimoreUnited States
- Department of Pharmacology, University of California, San DiegoLa JollaUnited States
| | - Michael Getz
- Chemical Engineering Graduate Program, University of California, San DiegoLa JollaUnited States
| | - Brian Ross
- Department of Pharmacology, University of California, San DiegoLa JollaUnited States
| | - Donya Ohadi
- Department of Mechanical and Aerospace Engineering, University of California, San DiegoLa JollaUnited States
| | - Christopher H Bohrer
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Eric Greenwald
- Department of Pharmacology, University of California, San DiegoLa JollaUnited States
| | - Sohum Mehta
- Department of Pharmacology, University of California, San DiegoLa JollaUnited States
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, The Johns Hopkins University School of MedicineBaltimoreUnited States
| | - Padmini Rangamani
- Chemical Engineering Graduate Program, University of California, San DiegoLa JollaUnited States
- Department of Mechanical and Aerospace Engineering, University of California, San DiegoLa JollaUnited States
| | - Jin Zhang
- Department of Pharmacology, University of California, San DiegoLa JollaUnited States
- Department of Chemistry and Biochemistry, University of California, San DiegoLa JollaUnited States
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Abstract
Diffusion within bacteria is often thought of as a "simple" random process by which molecules collide and interact with each other. New research however shows that this is far from the truth. Here we shed light on the complexity and importance of diffusion in bacteria, illustrating the similarities and differences of diffusive behaviors of molecules within different compartments of bacterial cells. We first describe common methodologies used to probe diffusion and the associated models and analyses. We then discuss distinct diffusive behaviors of molecules within different bacterial cellular compartments, highlighting the influence of metabolism, size, crowding, charge, binding, and more. We also explicitly discuss where further research and a united understanding of what dictates diffusive behaviors across the different compartments of the cell are required, pointing out new research avenues to pursue.
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Affiliation(s)
- Christopher H Bohrer
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA.
- Department of Biophysics, Johns Hopkins University, Baltimore, MD, USA.
| | - Jie Xiao
- Department of Biophysics and Biophysical Chemistry, Johns Hopkins School of Medicine, Baltimore, MD, USA.
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Bohrer CH, Roberts E, Xiao J. The Chromosome's Fight Against Disorder in E. coli. Biophys J 2019. [DOI: 10.1016/j.bpj.2018.11.437] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Bohrer CH, Roberts E. A Biophysical Model of Supercoiling Dependent Transcription Predicts a Structural Aspect to Gene Regulation. Biophys J 2017. [DOI: 10.1016/j.bpj.2016.11.3078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
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Bohrer CH, Roberts E. A biophysical model of supercoiling dependent transcription predicts a structural aspect to gene regulation. BMC Biophys 2016; 9:2. [PMID: 26855771 PMCID: PMC4744432 DOI: 10.1186/s13628-016-0027-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 01/28/2016] [Indexed: 11/15/2022]
Abstract
Background Transcription in Escherichia coli generates positive supercoiling in the DNA, which is relieved by the enzymatic activity of gyrase. Recently published experimental evidence suggests that transcription initiation and elongation are inhibited by the buildup of positive supercoiling. It has therefore been proposed that intermittent binding of gyrase plays a role in transcriptional bursting. Considering that transcription is one of the most fundamental cellular processes, it is desirable to be able to account for the buildup and release of positive supercoiling in models of transcription. Results Here we present a detailed biophysical model of gene expression that incorporates the effects of supercoiling due to transcription. By directly linking the amount of positive supercoiling to the rate of transcription, the model predicts that highly transcribed genes’ mRNA distributions should substantially deviate from Poisson distributions, with enhanced density at low mRNA copy numbers. Additionally, the model predicts a high degree of correlation between expression levels of genes inside the same supercoiling domain. Conclusions Our model, incorporating the supercoiling state of the gene, makes specific predictions that differ from previous models of gene expression. Genes in the same supercoiling domain influence the expression level of neighboring genes. Such structurally dependent regulation predicts correlations between genes in the same supercoiling domain. The topology of the chromosome therefore creates a higher level of gene regulation, which has broad implications for understanding the evolution and organization of bacterial genomes. Electronic supplementary material The online version of this article (doi:10.1186/s13628-016-0027-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Christopher H Bohrer
- Department of Biophysics, Johns Hopkins University, 3400 N Charles St, Baltimore, USA
| | - Elijah Roberts
- Department of Biophysics, Johns Hopkins University, 3400 N Charles St, Baltimore, USA
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