1
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Hannon CE, Eisen MB. Intrinsic protein disorder is insufficient to drive subnuclear clustering in embryonic transcription factors. eLife 2024; 12:RP88221. [PMID: 38275292 PMCID: PMC10945700 DOI: 10.7554/elife.88221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2024] Open
Abstract
Modern microscopy has revealed that core nuclear functions, including transcription, replication, and heterochromatin formation, occur in spatially restricted clusters. Previous work from our lab has shown that subnuclear high-concentration clusters of transcription factors may play a role in regulating RNA synthesis in the early Drosophila embryo. A nearly ubiquitous feature of eukaryotic transcription factors is that they contain intrinsically disordered regions (IDRs) that often arise from low complexity amino acid sequences within the protein. It has been proposed that IDRs within transcription factors drive co-localization of transcriptional machinery and target genes into high-concentration clusters within nuclei. Here, we test that hypothesis directly, by conducting a broad survey of the subnuclear localization of IDRs derived from transcription factors. Using a novel algorithm to identify IDRs in the Drosophila proteome, we generated a library of IDRs from transcription factors expressed in the early Drosophila embryo. We used this library to perform a high-throughput imaging screen in Drosophila Schneider-2 (S2) cells. We found that while subnuclear clustering does not occur when the majority of IDRs are expressed alone, it is frequently seen in full-length transcription factors. These results are consistent in live Drosophila embryos, suggesting that IDRs are insufficient to drive the subnuclear clustering behavior of transcription factors. Furthermore, the clustering of transcription factors in living embryos was unaffected by the deletion of IDR sequences. Our results demonstrate that IDRs are unlikely to be the primary molecular drivers of the clustering observed during transcription, suggesting a more complex and nuanced role for these disordered protein sequences.
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Affiliation(s)
- Colleen E Hannon
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
| | - Michael B Eisen
- Howard Hughes Medical Institute, University of CaliforniaBerkeleyUnited States
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2
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Nguyen TD, Chen YI, Chen LH, Yeh HC. Recent Advances in Single-Molecule Tracking and Imaging Techniques. ANNUAL REVIEW OF ANALYTICAL CHEMISTRY (PALO ALTO, CALIF.) 2023; 16:253-284. [PMID: 37314878 DOI: 10.1146/annurev-anchem-091922-073057] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Since the early 1990s, single-molecule detection in solution at room temperature has enabled direct observation of single biomolecules at work in real time and under physiological conditions, providing insights into complex biological systems that the traditional ensemble methods cannot offer. In particular, recent advances in single-molecule tracking techniques allow researchers to follow individual biomolecules in their native environments for a timescale of seconds to minutes, revealing not only the distinct pathways these biomolecules take for downstream signaling but also their roles in supporting life. In this review, we discuss various single-molecule tracking and imaging techniques developed to date, with an emphasis on advanced three-dimensional (3D) tracking systems that not only achieve ultrahigh spatiotemporal resolution but also provide sufficient working depths suitable for tracking single molecules in 3D tissue models. We then summarize the observables that can be extracted from the trajectory data. Methods to perform single-molecule clustering analysis and future directions are also discussed.
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Affiliation(s)
- Trung Duc Nguyen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Yuan-I Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Limin H Chen
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
| | - Hsin-Chih Yeh
- Department of Biomedical Engineering, University of Texas at Austin, Austin, Texas, USA;
- Texas Materials Institute, University of Texas at Austin, Austin, Texas, USA
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3
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Multiple parameters shape the 3D chromatin structure of single nuclei at the doc locus in Drosophila. Nat Commun 2022; 13:5375. [PMID: 36104317 PMCID: PMC9474875 DOI: 10.1038/s41467-022-32973-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Accepted: 08/25/2022] [Indexed: 11/08/2022] Open
Abstract
AbstractThe spatial organization of chromatin at the scale of topologically associating domains (TADs) and below displays large cell-to-cell variations. Up until now, how this heterogeneity in chromatin conformation is shaped by chromatin condensation, TAD insulation, and transcription has remained mostly elusive. Here, we used Hi-M, a multiplexed DNA-FISH imaging technique providing developmental timing and transcriptional status, to show that the emergence of TADs at the ensemble level partially segregates the conformational space explored by single nuclei during the early development of Drosophila embryos. Surprisingly, a substantial fraction of nuclei display strong insulation even before TADs emerge. Moreover, active transcription within a TAD leads to minor changes to the local inter- and intra-TAD chromatin conformation in single nuclei and only weakly affects insulation to the neighboring TAD. Overall, our results indicate that multiple parameters contribute to shaping the chromatin architecture of single nuclei at the TAD scale.
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4
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Solano A, Lou J, Scipioni L, Gratton E, Hinde E. Radial pair correlation of molecular brightness fluctuations maps protein diffusion as a function of oligomeric state within live-cell nuclear architecture. Biophys J 2022; 121:2152-2167. [PMID: 35490296 PMCID: PMC9247470 DOI: 10.1016/j.bpj.2022.04.030] [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: 06/08/2021] [Revised: 11/16/2021] [Accepted: 04/26/2022] [Indexed: 11/22/2022] Open
Abstract
Nuclear proteins can modulate their DNA binding activity and the exploration volume available during DNA target search by self-associating into higher-order oligomers. Directly tracking this process in the nucleoplasm of a living cell is, however, a complex task. Thus, here we present a microscopy method based on radial pair correlation of molecular brightness fluctuations (radial pCOMB) that can extract the mobility of a fluorescently tagged nuclear protein as a function of its oligomeric state and spatiotemporally map the anisotropy of this parameter with respect to nuclear architecture. By simply performing a rapid frame scan acquisition, radial pCOMB has the capacity to detect, within each pixel, protein oligomer formation and the size-dependent obstruction nuclear architecture imparts on this complex's transport across sub-micrometer distances. From application of radial pCOMB to an oligomeric transcription factor and DNA repair protein, we demonstrate that homo-oligomer formation differentially regulates chromatin accessibility and interaction with the DNA template.
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Affiliation(s)
- Ashleigh Solano
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Jieqiong Lou
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne
| | - Lorenzo Scipioni
- Department of Biomedical Engineering, University of California, Irvine
| | - Enrico Gratton
- Department of Biomedical Engineering, University of California, Irvine.
| | - Elizabeth Hinde
- School of Physics, University of Melbourne; Department of Biochemistry and Pharmacology, University of Melbourne.
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5
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Kenworthy CA, Haque N, Liou SH, Chandris P, Wong V, Dziuba P, Lavis LD, Liu WL, Singer RH, Coleman RA. Bromodomains regulate dynamic targeting of the PBAF chromatin-remodeling complex to chromatin hubs. Biophys J 2022; 121:1738-1752. [PMID: 35364106 PMCID: PMC9117891 DOI: 10.1016/j.bpj.2022.03.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/20/2021] [Accepted: 03/24/2022] [Indexed: 11/12/2022] Open
Abstract
Chromatin remodelers actively target arrays of acetylated nucleosomes at select enhancers and promoters to facilitate or shut down the repeated recruitment of RNA polymerase II during transcriptional bursting. It is poorly understood how chromatin remodelers such as PBAF dynamically target different chromatin states inside a live cell. Our live-cell single-molecule fluorescence microscopy study reveals chromatin hubs throughout the nucleus where PBAF rapidly cycles on and off the genome. Deletion of PBAF's bromodomains impairs targeting and stable engagement of chromatin in hubs. Dual color imaging reveals that PBAF targets both euchromatic and heterochromatic hubs with distinct genome-binding kinetic profiles that mimic chromatin stability. Removal of PBAF's bromodomains stabilizes H3.3 binding within chromatin, indicating that bromodomains may play a direct role in remodeling of the nucleosome. Our data suggests that PBAF's dynamic bromodomain-mediated engagement of a nucleosome may reflect the chromatin-remodeling potential of differentially bound chromatin states.
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Affiliation(s)
- Charles A Kenworthy
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Nayem Haque
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Shu-Hao Liou
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Panagiotis Chandris
- Section on High Resolution Optical Imaging, National Institute on Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, Maryland
| | - Vincent Wong
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Patrycja Dziuba
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia
| | - Wei-Li Liu
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York
| | - Robert H Singer
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York; Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, Virginia
| | - Robert A Coleman
- Gruss-Lipper Biophotonics Center, Department of Cell Biology, Albert Einstein College of Medicine, New York.
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6
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Weidemüller P, Kholmatov M, Petsalaki E, Zaugg JB. Transcription factors: Bridge between cell signaling and gene regulation. Proteomics 2021; 21:e2000034. [PMID: 34314098 DOI: 10.1002/pmic.202000034] [Citation(s) in RCA: 83] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 07/05/2021] [Accepted: 07/16/2021] [Indexed: 01/17/2023]
Abstract
Transcription factors (TFs) are key regulators of intrinsic cellular processes, such as differentiation and development, and of the cellular response to external perturbation through signaling pathways. In this review we focus on the role of TFs as a link between signaling pathways and gene regulation. Cell signaling tends to result in the modulation of a set of TFs that then lead to changes in the cell's transcriptional program. We highlight the molecular layers at which TF activity can be measured and the associated technical and conceptual challenges. These layers include post-translational modifications (PTMs) of the TF, regulation of TF binding to DNA through chromatin accessibility and epigenetics, and expression of target genes. We highlight that a large number of TFs are understudied in both signaling and gene regulation studies, and that our knowledge about known TF targets has a strong literature bias. We argue that TFs serve as a perfect bridge between the fields of gene regulation and signaling, and that separating these fields hinders our understanding of cell functions. Multi-omics approaches that measure multiple dimensions of TF activity are ideally suited to study the interplay of cell signaling and gene regulation using TFs as the anchor to link the two fields.
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Affiliation(s)
- Paula Weidemüller
- European Bioinformatics Institute, European Molecular Biology Laboratory, Wellcome Genome Campus, Hinxton, CB10 1SD, UK
| | - Maksim Kholmatov
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, Heidelberg, 69117, Germany
| | - Evangelia Petsalaki
- European Bioinformatics Institute, European Molecular Biology Laboratory, Wellcome Genome Campus, Hinxton, CB10 1SD, UK
| | - Judith B Zaugg
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Meyerhofstraße 1, Heidelberg, 69117, Germany
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7
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Holler K, Neuschulz A, Drewe-Boß P, Mintcheva J, Spanjaard B, Arsiè R, Ohler U, Landthaler M, Junker JP. Spatio-temporal mRNA tracking in the early zebrafish embryo. Nat Commun 2021; 12:3358. [PMID: 34099733 PMCID: PMC8184788 DOI: 10.1038/s41467-021-23834-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 05/18/2021] [Indexed: 01/17/2023] Open
Abstract
Early stages of embryogenesis depend on subcellular localization and transport of maternal mRNA. However, systematic analysis of these processes is hindered by a lack of spatio-temporal information in single-cell RNA sequencing. Here, we combine spatially-resolved transcriptomics and single-cell RNA labeling to perform a spatio-temporal analysis of the transcriptome during early zebrafish development. We measure spatial localization of mRNA molecules within the one-cell stage embryo, which allows us to identify a class of mRNAs that are specifically localized at an extraembryonic position, the vegetal pole. Furthermore, we establish a method for high-throughput single-cell RNA labeling in early zebrafish embryos, which enables us to follow the fate of individual maternal transcripts until gastrulation. This approach reveals that many localized transcripts are specifically transported to the primordial germ cells. Finally, we acquire spatial transcriptomes of two xenopus species and compare evolutionary conservation of localized genes as well as enriched sequence motifs.
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Affiliation(s)
- Karoline Holler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Anika Neuschulz
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Philipp Drewe-Boß
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Janita Mintcheva
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Bastiaan Spanjaard
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Roberto Arsiè
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Uwe Ohler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- Department of Biology, Humboldt University, Berlin, Germany
| | - Markus Landthaler
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany
- IRI Life Science, Institute of Biology, Humboldt University, Berlin, Germany
| | - Jan Philipp Junker
- Berlin Institute for Medical Systems Biology, Max Delbrück Center for Molecular Medicine, Berlin, Germany.
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8
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Co-condensation between transcription factor and coactivator p300 modulates transcriptional bursting kinetics. Mol Cell 2021; 81:1682-1697.e7. [PMID: 33651988 DOI: 10.1016/j.molcel.2021.01.031] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 11/23/2020] [Accepted: 01/21/2021] [Indexed: 12/16/2022]
Abstract
The coactivator p300/CREB-binding protein (CBP) regulates genes by facilitating the assembly of transcriptional machinery and by acetylating histones and other factors. However, it remains mostly unclear how both functions of p300 are dynamically coordinated during gene control. Here, we showed that p300 can orchestrate two functions through the formation of dynamic clusters with certain transcription factors (TFs), which is mediated by the interactions between a TF's transactivation domain (TAD) and the intrinsically disordered regions of p300. Co-condensation can enable spatially defined, all-or-none activation of p300's catalytic activity, priming the recruitment of coactivators, including Brd4. We showed that co-condensation can modulate transcriptional initiation rate and burst duration of target genes, underlying nonlinear gene regulatory functions. Such modulation is consistent with how p300 might shape gene bursting kinetics globally. Altogether, these results suggest an intriguing gene regulation mechanism, in which TF and p300 co-condensation contributes to transcriptional bursting regulation and cooperative gene control.
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9
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Abstract
Determining whether and how a gene is transcribed are two of the central processes of life. The conceptual basis for understanding such gene regulation arose from pioneering biophysical studies in eubacteria. However, eukaryotic genomes exhibit vastly greater complexity, which raises questions not addressed by this bacterial paradigm. First, how is information integrated from many widely separated binding sites to determine how a gene is transcribed? Second, does the presence of multiple energy-expending mechanisms, which are absent from eubacterial genomes, indicate that eukaryotes are capable of improved forms of genetic information processing? An updated biophysical foundation is needed to answer such questions. We describe the linear framework, a graph-based approach to Markov processes, and show that it can accommodate many previous studies in the field. Under the assumption of thermodynamic equilibrium, we introduce a language of higher-order cooperativities and show how it can rigorously quantify gene regulatory properties suggested by experiment. We point out that fundamental limits to information processing arise at thermodynamic equilibrium and can only be bypassed through energy expenditure. Finally, we outline some of the mathematical challenges that must be overcome to construct an improved biophysical understanding of gene regulation.
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Affiliation(s)
- Felix Wong
- Institute for Medical Engineering & Science, Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.,Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, Massachusetts 02142, USA
| | - Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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10
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de Jonge WJ, Brok M, Lijnzaad P, Kemmeren P, Holstege FCP. Genome-wide off-rates reveal how DNA binding dynamics shape transcription factor function. Mol Syst Biol 2020; 16:e9885. [PMID: 33280256 PMCID: PMC7586999 DOI: 10.15252/msb.20209885] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 09/06/2020] [Accepted: 09/10/2020] [Indexed: 11/25/2022] Open
Abstract
Protein-DNA interactions are dynamic, and these dynamics are an important aspect of chromatin-associated processes such as transcription or replication. Due to a lack of methods to study on- and off-rates across entire genomes, protein-DNA interaction dynamics have not been studied extensively. Here, we determine in vivo off-rates for the Saccharomyces cerevisiae chromatin organizing factor Abf1, at 191 sites simultaneously across the yeast genome. Average Abf1 residence times span a wide range, varying between 4.2 and 33 min. Sites with different off-rates are associated with different functional characteristics. This includes their transcriptional dependency on Abf1, nucleosome positioning and the size of the nucleosome-free region, as well as the ability to roadblock RNA polymerase II for termination. The results show how off-rates contribute to transcription factor function and that DIVORSEQ (Determining In Vivo Off-Rates by SEQuencing) is a meaningful way of investigating protein-DNA binding dynamics genome-wide.
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Affiliation(s)
- Wim J de Jonge
- Princess Máxima Center for Pediatric OncologyUtrechtThe Netherlands
| | - Mariël Brok
- Princess Máxima Center for Pediatric OncologyUtrechtThe Netherlands
| | - Philip Lijnzaad
- Princess Máxima Center for Pediatric OncologyUtrechtThe Netherlands
| | - Patrick Kemmeren
- Princess Máxima Center for Pediatric OncologyUtrechtThe Netherlands
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11
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Okamoto K. From a young BSJ member: advanced technologies encouraged me to dive into biophysics field. Biophys Rev 2020; 12:205-206. [PMID: 32090273 PMCID: PMC7242555 DOI: 10.1007/s12551-020-00648-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 02/11/2020] [Indexed: 11/30/2022] Open
Affiliation(s)
- Kazuko Okamoto
- Laboratory for Comprehensive Bioimaging, Center for Biosystems Dynamics Research, RIKEN, 3-10-23 Kagamiyama, The Research site in Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan.
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12
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Ferree P, Di Talia S. Developmental Biology: Embryos Need to Control Their Nucleotides Just Right. Curr Biol 2019; 29:R252-R254. [PMID: 30939309 DOI: 10.1016/j.cub.2019.02.051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The maternal-to-zygotic transition in the Drosophila embryo requires accurate control of the levels of free nucleotides, arguing for an essential role of nucleotide metabolism in the regulation of the cell cycle during early embryogenesis.
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Affiliation(s)
- Patrick Ferree
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
| | - Stefano Di Talia
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
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13
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Roeder RG. 50+ years of eukaryotic transcription: an expanding universe of factors and mechanisms. Nat Struct Mol Biol 2019; 26:783-791. [PMID: 31439941 DOI: 10.1038/s41594-019-0287-x] [Citation(s) in RCA: 109] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 07/26/2019] [Indexed: 12/12/2022]
Abstract
The landmark 1969 discovery of nuclear RNA polymerases I, II and III in diverse eukaryotes represented a major turning point in the field that, with subsequent elucidation of the distinct structures and functions of these enzymes, catalyzed an avalanche of further studies. In this Review, written from a personal and historical perspective, I highlight foundational biochemical studies that led to the discovery of an expanding universe of the components of the transcriptional and regulatory machineries, and a parallel complexity in gene-specific mechanisms that continue to be explored to the present day.
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Affiliation(s)
- Robert G Roeder
- Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, New York, USA.
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14
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Bartman CR, Hamagami N, Keller CA, Giardine B, Hardison RC, Blobel GA, Raj A. Transcriptional Burst Initiation and Polymerase Pause Release Are Key Control Points of Transcriptional Regulation. Mol Cell 2019; 73:519-532.e4. [PMID: 30554946 PMCID: PMC6368450 DOI: 10.1016/j.molcel.2018.11.004] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 08/06/2018] [Accepted: 11/01/2018] [Indexed: 11/16/2022]
Abstract
Transcriptional regulation occurs via changes to rates of different biochemical steps of transcription, but it remains unclear which rates are subject to change upon biological perturbation. Biochemical studies have suggested that stimuli predominantly affect the rates of RNA polymerase II (Pol II) recruitment and polymerase release from promoter-proximal pausing. Single-cell studies revealed that transcription occurs in discontinuous bursts, suggesting that features of such bursts like frequency and intensity could also be regulated. We combined Pol II chromatin immunoprecipitation sequencing (ChIP-seq) and single-cell transcriptional measurements to show that an independently regulated burst initiation step is required before polymerase recruitment can occur. Using a number of global and targeted transcriptional regulatory perturbations, we showed that biological perturbations regulated both burst initiation and polymerase pause release rates but seemed not to regulate polymerase recruitment rate. Our results suggest that transcriptional regulation primarily acts by changing the rates of burst initiation and polymerase pause release.
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Affiliation(s)
- Caroline R Bartman
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nicole Hamagami
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Cheryl A Keller
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Belinda Giardine
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Ross C Hardison
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA 16802, USA
| | - Gerd A Blobel
- Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA; Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
| | - Arjun Raj
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA; Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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15
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Roy AL, Conroy RS. Toward mapping the human body at a cellular resolution. Mol Biol Cell 2018; 29:1779-1785. [PMID: 30058989 PMCID: PMC6085824 DOI: 10.1091/mbc.e18-04-0260] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Revised: 06/01/2018] [Accepted: 06/07/2018] [Indexed: 12/21/2022] Open
Abstract
The adult human body is composed of nearly 37 trillion cells, each with potentially unique molecular characteristics. This Perspective describes some of the challenges and opportunities faced in mapping the molecular characteristics of these cells in specific regions of the body and highlights areas for international collaboration toward the broader goal of comprehensively mapping the human body with cellular resolution.
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Affiliation(s)
- Ananda L. Roy
- Office of Strategic Coordination, Division of Program Coordination, Planning, and Strategic Initiatives, Office of the Director, National Institutes of Health, Bethesda, MD 20892
| | - Richard S. Conroy
- Office of Strategic Coordination, Division of Program Coordination, Planning, and Strategic Initiatives, Office of the Director, National Institutes of Health, Bethesda, MD 20892
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16
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Goldstein I, Hager GL. Dynamic enhancer function in the chromatin context. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2018; 10:10.1002/wsbm.1390. [PMID: 28544514 PMCID: PMC6638546 DOI: 10.1002/wsbm.1390] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 03/21/2017] [Accepted: 03/23/2017] [Indexed: 12/28/2022]
Abstract
Enhancers serve as critical regulatory elements in higher eukaryotic cells. The characterization of enhancer function has evolved primarily from genome-wide methodologies, including chromatin immunoprecipitation (ChIP-seq), DNase-I hypersensitivity (DNase-seq), digital genomic footprinting (DGF), and the chromosome conformation capture techniques (3C, 4C, and Hi-C). These population-based assays average signals across millions of cells and lead to enhancer models characterized by static and sequential binding. More recently, fluorescent microscopy techniques, including fluorescence recovery after photobleaching, fluorescence correlation spectroscopy, and single molecule tracking (SMT), reveal a highly dynamic binding behavior for these factors in live cells. Furthermore, a refined analysis of genomic footprinting suggests that many transcription factors leave minimal or no footprints in chromatin, even when present and active in a given cell type. In this study, we review the implications of these new approaches for an accurate understanding of enhancer function in real time. In vivo SMT, in particular, has recently evolved as a promising methodology to probe enhancer function in live cells. Integration of findings from the many approaches now employed in the study of enhancer function suggest a highly dynamic view for the action of enhancer activating factors, viewed on a time scale of milliseconds to seconds, rather than minutes to hours. WIREs Syst Biol Med 2018, 10:e1390. doi: 10.1002/wsbm.1390 This article is categorized under: Analytical and Computational Methods > Computational Methods Laboratory Methods and Technologies > Genetic/Genomic Methods Laboratory Methods and Technologies > Imaging.
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Affiliation(s)
- Ido Goldstein
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Gordon L. Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
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17
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Tycko J, Van MV, Elowitz MB, Bintu L. Advancing towards a global mammalian gene regulation model through single-cell analysis and synthetic biology. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2017. [DOI: 10.1016/j.cobme.2017.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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18
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Zhang Z, Tjian R. Measuring dynamics of eukaryotic transcription initiation: Challenges, insights and opportunities. Transcription 2017; 9:159-165. [PMID: 28920762 PMCID: PMC5927711 DOI: 10.1080/21541264.2017.1363017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Transcription of protein-encoding genes in eukaryotic cells is a dynamically coordinated process. Many of the key transcription regulators contain functionally essential intrinsically disordered regions (IDRs), the dynamic nature of which creates extra challenges to traditional biochemical analyses. Recent advances in single-molecule fluorescence imaging technology have enabled direct visualization of these rapid, complex and dynamic molecular interactions in real time.
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Affiliation(s)
| | - Robert Tjian
- b Howard Hughes Medical Institute, Li Ka Shing Center for Biomedical and Health Sciences and Department of Molecular and Cell Biology, University of California , Berkeley , CA , USA
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19
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Dynamics and regulation of nuclear import and nuclear movements of HIV-1 complexes. PLoS Pathog 2017; 13:e1006570. [PMID: 28827840 PMCID: PMC5578721 DOI: 10.1371/journal.ppat.1006570] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 08/31/2017] [Accepted: 08/05/2017] [Indexed: 11/19/2022] Open
Abstract
The dynamics and regulation of HIV-1 nuclear import and its intranuclear movements after import have not been studied. To elucidate these essential HIV-1 post-entry events, we labeled viral complexes with two fluorescently tagged virion-incorporated proteins (APOBEC3F or integrase), and analyzed the HIV-1 dynamics of nuclear envelope (NE) docking, nuclear import, and intranuclear movements in living cells. We observed that HIV-1 complexes exhibit unusually long NE residence times (1.5±1.6 hrs) compared to most cellular cargos, which are imported into the nuclei within milliseconds. Furthermore, nuclear import requires HIV-1 capsid (CA) and nuclear pore protein Nup358, and results in significant loss of CA, indicating that one of the viral core uncoating steps occurs during nuclear import. Our results showed that the CA-Cyclophilin A interaction regulates the dynamics of nuclear import by delaying the time of NE docking as well as transport through the nuclear pore, but blocking reverse transcription has no effect on the kinetics of nuclear import. We also visualized the translocation of viral complexes docked at the NE into the nucleus and analyzed their nuclear movements and determined that viral complexes exhibited a brief fast phase (<9 min), followed by a long slow phase lasting several hours. A comparison of the movement of viral complexes to those of proviral transcription sites supports the hypothesis that HIV-1 complexes quickly tether to chromatin at or near their sites of integration in both wild-type cells and cells in which LEDGF/p75 was deleted using CRISPR/cas9, indicating that the tethering interactions do not require LEDGF/p75. These studies provide novel insights into the dynamics of viral complex-NE association, regulation of nuclear import, viral core uncoating, and intranuclear movements that precede integration site selection. Although nuclear import of HIV-1 is essential for viral replication, many aspects of this process are currently unknown. Here, we defined the dynamics of HIV-1 nuclear envelope (NE) docking, nuclear import and its relationship to viral core uncoating, and intranuclear movements. We observed that HIV-1 complexes exhibit an unusually long residence time at the NE (∼1.5 hrs) compared to other cellular and viral cargos, and that HIV-1 capsid (CA) and host nuclear pore protein Nup358 are required for NE docking and nuclear import. Soon after import, the viral complexes exhibit a brief fast phase of movement, followed by a long slow phase, during which their movement is similar to that of integrated proviruses, suggesting that they rapidly become tethered to chromatin through interactions that do not require LEDGF/p75. Importantly, we found that NE association and nuclear import is regulated by the CA-cyclophilin A interaction, but not reverse transcription, and that one of the viral core uncoating steps, characterized by substantial loss of CA, occurs concurrently with nuclear import.
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20
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Mapping the Dynamics of the Glucocorticoid Receptor within the Nuclear Landscape. Sci Rep 2017; 7:6219. [PMID: 28740156 PMCID: PMC5524710 DOI: 10.1038/s41598-017-06676-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 06/15/2017] [Indexed: 12/28/2022] Open
Abstract
The distribution of the transcription machinery among different sub-nuclear domains raises the question on how the architecture of the nucleus modulates the transcriptional response. Here, we used fluorescence fluctuation analyses to quantitatively explore the organization of the glucocorticoid receptor (GR) in the interphase nucleus of living cells. We found that this ligand-activated transcription factor diffuses within the nucleus and dynamically interacts with bodies enriched in the coregulator NCoA-2, DNA-dependent foci and chromatin targets. The distribution of the receptor among the nuclear compartments depends on NCoA-2 and the conformation of the receptor as assessed with synthetic ligands and GR mutants with impaired transcriptional abilities. Our results suggest that the partition of the receptor in different nuclear reservoirs ultimately regulates the concentration of receptor available for the interaction with specific targets, and thus has an impact on transcription regulation.
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21
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Abstract
For tissue regeneration researchers, seeing is believing. Here, we consider advances in genetic tools, imaging platforms, and quantification capabilities that are turning previously unattainable goals, like in toto capture of cellular and subcellular behaviors in regenerating tissues, into reality.
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Affiliation(s)
- Stefano Di Talia
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA.
| | - Kenneth D Poss
- Department of Cell Biology, Duke University School of Medicine, Durham, NC 27710, USA.
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22
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Presman DM, Ball DA, Paakinaho V, Grimm JB, Lavis LD, Karpova TS, Hager GL. Quantifying transcription factor binding dynamics at the single-molecule level in live cells. Methods 2017; 123:76-88. [PMID: 28315485 PMCID: PMC5522764 DOI: 10.1016/j.ymeth.2017.03.014] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 01/30/2017] [Accepted: 03/10/2017] [Indexed: 11/25/2022] Open
Abstract
Progressive, technological achievements in the quantitative fluorescence microscopy field are allowing researches from many different areas to start unraveling the dynamic intricacies of biological processes inside living cells. From super-resolution microscopy techniques to tracking of individual proteins, fluorescence microscopy is changing our perspective on how the cell works. Fortunately, a growing number of research groups are exploring single-molecule studies in living cells. However, no clear consensus exists on several key aspects of the technique such as image acquisition conditions, or analysis of the obtained data. Here, we describe a detailed approach to perform single-molecule tracking (SMT) of transcription factors in living cells to obtain key binding characteristics, namely their residence time and bound fractions. We discuss different types of fluorophores, labeling density, microscope, cameras, data acquisition, and data analysis. Using the glucocorticoid receptor as a model transcription factor, we compared alternate tags (GFP, mEOS, HaloTag, SNAP-tag, CLIP-tag) for potential multicolor applications. We also examine different methods to extract the dissociation rates and compare them with simulated data. Finally, we discuss several challenges that this exciting technique still faces.
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Affiliation(s)
- Diego M Presman
- Laboratory of Receptor Biology and Gene Expression, Building 41, 41 Library Drive, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - David A Ball
- Laboratory of Receptor Biology and Gene Expression, Building 41, 41 Library Drive, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ville Paakinaho
- Laboratory of Receptor Biology and Gene Expression, Building 41, 41 Library Drive, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, 19700 Helix Drive, Ashburn, VA 20147, USA
| | - Tatiana S Karpova
- Laboratory of Receptor Biology and Gene Expression, Building 41, 41 Library Drive, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, Building 41, 41 Library Drive, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
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23
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Pankert T, Jegou T, Caudron-Herger M, Rippe K. Tethering RNA to chromatin for fluorescence microscopy based analysis of nuclear organization. Methods 2017; 123:89-101. [DOI: 10.1016/j.ymeth.2017.01.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2016] [Revised: 01/23/2017] [Accepted: 01/30/2017] [Indexed: 12/22/2022] Open
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24
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Quantifying transcription factor–DNA binding in single cells in vivo with photoactivatable fluorescence correlation spectroscopy. Nat Protoc 2017; 12:1458-1471. [DOI: 10.1038/nprot.2017.051] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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25
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Cuvier O, Fierz B. Dynamic chromatin technologies: from individual molecules to epigenomic regulation in cells. Nat Rev Genet 2017; 18:457-472. [DOI: 10.1038/nrg.2017.28] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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26
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Vera M, Biswas J, Senecal A, Singer RH, Park HY. Single-Cell and Single-Molecule Analysis of Gene Expression Regulation. Annu Rev Genet 2017; 50:267-291. [PMID: 27893965 DOI: 10.1146/annurev-genet-120215-034854] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent advancements in single-cell and single-molecule imaging technologies have resolved biological processes in time and space that are fundamental to understanding the regulation of gene expression. Observations of single-molecule events in their cellular context have revealed highly dynamic aspects of transcriptional and post-transcriptional control in eukaryotic cells. This approach can relate transcription with mRNA abundance and lifetimes. Another key aspect of single-cell analysis is the cell-to-cell variability among populations of cells. Definition of heterogeneity has revealed stochastic processes, determined characteristics of under-represented cell types or transitional states, and integrated cellular behaviors in the context of multicellular organisms. In this review, we discuss novel aspects of gene expression of eukaryotic cells and multicellular organisms revealed by the latest advances in single-cell and single-molecule imaging technology.
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Affiliation(s)
- Maria Vera
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, NY 10461; , , ,
| | - Jeetayu Biswas
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, NY 10461; , , ,
| | - Adrien Senecal
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, NY 10461; , , ,
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, New York, NY 10461; , , , .,Janelia Research Campus of the HHMI, Ashburn, Virginia 20147
| | - Hye Yoon Park
- Department of Physics and Astronomy, Seoul National University, Seoul, 08826, Korea; .,Institute of Molecular Biology and Genetics, Seoul National University, Seoul, 08826, Korea
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27
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Imaging Translational and Post-Translational Gene Regulatory Dynamics in Living Cells with Antibody-Based Probes. Trends Genet 2017; 33:322-335. [PMID: 28359585 DOI: 10.1016/j.tig.2017.02.003] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 02/25/2017] [Accepted: 02/28/2017] [Indexed: 12/17/2022]
Abstract
Antibody derivatives, such as antibody fragments (Fabs) and single-chain variable fragments (scFvs), are now being used to image traditionally hard-to-see protein subpopulations, including nascent polypeptides being translated and post-translationally modified proteins. This has allowed researchers to directly image and quantify, for the first time, translation initiation and elongation kinetics with single-transcript resolution and the temporal ordering and kinetics of post-translational histone and RNA polymerase II modifications. Here, we review these developments and discuss the strengths and weaknesses of live-cell imaging with antibody-based probes. Further development of these probes will increase their versatility and open new avenues of research for dissecting complex gene regulatory dynamics.
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28
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Sanchez OF, Mendonca A, Carneiro AD, Yuan C. Engineering Recombinant Protein Sensors for Quantifying Histone Acetylation. ACS Sens 2017; 2:426-435. [PMID: 28723212 DOI: 10.1021/acssensors.7b00026] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
H3K14ac (acetylation of lysine 14 of histone H3) is one of the most important epigentic modifications. Aberrant changes in H3K14ac have been associated with various diseases, including cancers and neurological disorders. Tools that enable detection and quantification of H3K14ac levels in cell extracts and in situ are thus of critical importance to reveal its role in various biological processes. Current detection techniques of specific histone modifications, however, are constrained by tedious sample pretreatments, lack of quantitative accuracy, and reliance on high quality antibodies. To address this issue, we engineered recombinant sensors that are suitable for probing histone acetylation levels using various biological samples. The protein sensor contains recongition domain(s) with sequences derived from the bromodomain of human polybromo-1 (PB1), a natural H3K14ac reader domain. Various sensor designs were tested using nuclear extracts and live cells. The sensor containing dimeric repeats of bromodomain was found most effective in quantifying H3K14ac level in both in vitro and in situ assays. The sensor has a linear detection range of 0.5-50 nM when mixed with nuclear extracts. The sensor colocalizes with H3K14ac antibodies in situ when transfected into human embryonic kidney 293T (HEK293T) cells and is thus capable of providing spatial details of histone modification within the nucleus. Corrected nuclear fluorescence intensity was used to quantify the modification level in situ and found to correlate well with our in vitro assays. Our sensor offers a novel tool to characterize the histone modification level using nuclear extracts and probe histone modification change in live cells.
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Affiliation(s)
- Oscar F. Sanchez
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Agnes Mendonca
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Ana D. Carneiro
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
| | - Chongli Yuan
- School of Chemical Engineering, Purdue University, 480 Stadium Mall Drive, West Lafayette, Indiana 47907, United States
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29
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Eliscovich C, Singer RH. RNP transport in cell biology: the long and winding road. Curr Opin Cell Biol 2017; 45:38-46. [PMID: 28258033 DOI: 10.1016/j.ceb.2017.02.008] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 01/17/2017] [Accepted: 02/08/2017] [Indexed: 01/08/2023]
Abstract
Regulation of gene expression is key determinant to cell structure and function. RNA localization, where specific mRNAs are transported to subcellular regions and then translated, is highly conserved in eukaryotes ranging from yeast to extremely specialized and polarized cells such as neurons. Messenger RNA and associated proteins (mRNP) move from the site of transcription in the nucleus to their final destination in the cytoplasm both passively through diffusion and actively via directed transport. Dysfunction of RNA localization, transport and translation machinery can lead to pathology. Single-molecule live-cell imaging techniques have revealed unique features of this journey with unprecedented resolution. In this review, we highlight key recent findings that have been made using these approaches and possible implications for spatial control of gene function.
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Affiliation(s)
- Carolina Eliscovich
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, United States; Current address: Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, United States
| | - Robert H Singer
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, United States; Gruss Lipper Biophotonics Center, Albert Einstein College of Medicine, Bronx, New York 10461, United States; Janelia Research Campus of the HHMI, Ashburn, VA, 20147, United States.
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30
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Custer TC, Walter NG. In vitro labeling strategies for in cellulo fluorescence microscopy of single ribonucleoprotein machines. Protein Sci 2017; 26:1363-1379. [PMID: 28028853 PMCID: PMC5477532 DOI: 10.1002/pro.3108] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 12/20/2016] [Accepted: 12/21/2016] [Indexed: 12/20/2022]
Abstract
RNA plays a fundamental, ubiquitous role as either substrate or functional component of many large cellular complexes-"molecular machines"-used to maintain and control the readout of genetic information, a functional landscape that we are only beginning to understand. The cellular mechanisms for the spatiotemporal organization of the plethora of RNAs involved in gene expression are particularly poorly understood. Intracellular single-molecule fluorescence microscopy provides a powerful emerging tool for probing the pertinent mechanistic parameters that govern cellular RNA functions, including those of protein coding messenger RNAs (mRNAs). Progress has been hampered, however, by the scarcity of efficient high-yield methods to fluorescently label RNA molecules without the need to drastically increase their molecular weight through artificial appendages that may result in altered behavior. Herein, we employ T7 RNA polymerase to body label an RNA with a cyanine dye, as well as yeast poly(A) polymerase to strategically place multiple 2'-azido-modifications for subsequent fluorophore labeling either between the body and tail or randomly throughout the tail. Using a combination of biochemical and single-molecule fluorescence microscopy approaches, we demonstrate that both yeast poly(A) polymerase labeling strategies result in fully functional mRNA, whereas protein coding is severely diminished in the case of body labeling.
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Affiliation(s)
- Thomas C Custer
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan, 48109.,Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109
| | - Nils G Walter
- Single Molecule Analysis Group and Center for RNA Biomedicine, Department of Chemistry, University of Michigan, Ann Arbor, Michigan, 48109
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31
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Zhao ZW, White MD, Bissiere S, Levi V, Plachta N. Quantitative imaging of mammalian transcriptional dynamics: from single cells to whole embryos. BMC Biol 2016; 14:115. [PMID: 28010727 PMCID: PMC5180410 DOI: 10.1186/s12915-016-0331-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Probing dynamic processes occurring within the cell nucleus at the quantitative level has long been a challenge in mammalian biology. Advances in bio-imaging techniques over the past decade have enabled us to directly visualize nuclear processes in situ with unprecedented spatial and temporal resolution and single-molecule sensitivity. Here, using transcription as our primary focus, we survey recent imaging studies that specifically emphasize the quantitative understanding of nuclear dynamics in both time and space. These analyses not only inform on previously hidden physical parameters and mechanistic details, but also reveal a hierarchical organizational landscape for coordinating a wide range of transcriptional processes shared by mammalian systems of varying complexity, from single cells to whole embryos.
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Affiliation(s)
- Ziqing W Zhao
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore, 138673, Singapore
| | - Melanie D White
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore, 138673, Singapore
| | - Stephanie Bissiere
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore, 138673, Singapore
| | - Valeria Levi
- Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Conicet, Buenos Aires, C1428EHA, Argentina
| | - Nicolas Plachta
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), 61 Biopolis Drive, Singapore, 138673, Singapore.
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32
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Cui Y, Liu J, Irudayaraj J. Beyond quantification: in situ analysis of transcriptome and pre-mRNA alternative splicing at the nanoscale. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2016; 9. [PMID: 27813271 DOI: 10.1002/wnan.1443] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 09/02/2016] [Accepted: 10/02/2016] [Indexed: 11/08/2022]
Abstract
In situ analysis offers a venue for dissecting the complex transcriptome in its natural context to tap into cellular processes that could explain the phenotypic physiology and pathology yet to be understood. Over the past decades, enormous progress has been made to improve the resolution, sensitivity, and specificity of single-cell technologies. The continued efforts in RNA research not only facilitates mechanistic studies of molecular biology but also provides state-of-the-art strategies for diagnostic purposes. The implementation of novel bio-imaging platforms has yielded valuable information for inspecting gene expression, mapping regulatory networks, and classifying cell types. In this article, we discuss the merits and technical challenges in single-molecule in situ RNA profiling. Advanced in situ hybridization methodologies developed for a variety of detection modalities are reviewed. Considering the fact that in mammalian cells the number of protein products immensely exceeds that of the actual coding genes due to pre-mRNA alternative splicing, tools capable of elucidating this process in intact cells are highlighted. To conclude, we point out future directions for in situ transcriptome analysis and expect a plethora of opportunities and discoveries in this field. WIREs Nanomed Nanobiotechnol 2017, 9:e1443. doi: 10.1002/wnan.1443 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Yi Cui
- Department of Agricultural and Biological Engineering, Bindley Bioscience Center and Birck Nanotechnology Center, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, USA.,Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, WA, USA
| | - Jing Liu
- Department of Nanoscience and Nanoengineering, South Dakota School of Mines & Technology, Rapid City, SD, USA
| | - Joseph Irudayaraj
- Department of Agricultural and Biological Engineering, Bindley Bioscience Center and Birck Nanotechnology Center, Purdue Center for Cancer Research, Purdue University, West Lafayette, IN, USA
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33
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Zhen CY, Tatavosian R, Huynh TN, Duc HN, Das R, Kokotovic M, Grimm JB, Lavis LD, Lee J, Mejia FJ, Li Y, Yao T, Ren X. Live-cell single-molecule tracking reveals co-recognition of H3K27me3 and DNA targets polycomb Cbx7-PRC1 to chromatin. eLife 2016; 5. [PMID: 27723458 PMCID: PMC5056789 DOI: 10.7554/elife.17667] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Accepted: 08/29/2016] [Indexed: 12/11/2022] Open
Abstract
The Polycomb PRC1 plays essential roles in development and disease pathogenesis. Targeting of PRC1 to chromatin is thought to be mediated by the Cbx family proteins (Cbx2/4/6/7/8) binding to histone H3 with a K27me3 modification (H3K27me3). Despite this prevailing view, the molecular mechanisms of targeting remain poorly understood. Here, by combining live-cell single-molecule tracking (SMT) and genetic engineering, we reveal that H3K27me3 contributes significantly to the targeting of Cbx7 and Cbx8 to chromatin, but less to Cbx2, Cbx4, and Cbx6. Genetic disruption of the complex formation of PRC1 facilitates the targeting of Cbx7 to chromatin. Biochemical analyses uncover that the CD and AT-hook-like (ATL) motif of Cbx7 constitute a functional DNA-binding unit. Live-cell SMT of Cbx7 mutants demonstrates that Cbx7 is targeted to chromatin by co-recognizing of H3K27me3 and DNA. Our data suggest a novel hierarchical cooperation mechanism by which histone modifications and DNA coordinate to target chromatin regulatory complexes. DOI:http://dx.doi.org/10.7554/eLife.17667.001
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Affiliation(s)
- Chao Yu Zhen
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Roubina Tatavosian
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Thao Ngoc Huynh
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Huy Nguyen Duc
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Raibatak Das
- Department of Integrative Biology, University of Colorado Denver, Denver, United States
| | - Marko Kokotovic
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Jonathan B Grimm
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Luke D Lavis
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, United States
| | - Jun Lee
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Frances J Mejia
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Yang Li
- Department of Chemistry, University of Colorado Denver, Denver, United States
| | - Tingting Yao
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, United States
| | - Xiaojun Ren
- Department of Chemistry, University of Colorado Denver, Denver, United States
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