1
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Goluguri RR, Ghosh C, Quintong J, Sadqi M, Muñoz V. How to scan naked DNA using promiscuous recognition and no clamping: a model for pioneer transcription factors. Nucleic Acids Res 2024:gkae790. [PMID: 39287129 DOI: 10.1093/nar/gkae790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Revised: 08/22/2024] [Accepted: 09/03/2024] [Indexed: 09/19/2024] Open
Abstract
Most DNA scanning proteins uniquely recognize their cognate sequence motif and slide on DNA assisted by some sort of clamping interface. The pioneer transcription factors that control cell fate in eukaryotes must forgo both elements to gain access to DNA in naked and chromatin forms; thus, whether or how these factors scan naked DNA is unknown. Here, we use single-molecule techniques to investigate naked DNA scanning by the Engrailed homeodomain (enHD) as paradigm of highly promiscuous recognition and open DNA binding interface. We find that enHD scans naked DNA quite effectively, and about 200000-fold faster than expected for a continuous promiscuous slide. To do so, enHD scans about 675 bp of DNA in 100 ms and then redeploys stochastically to another location 530 bp afar in just 10 ms. During the scanning phase enHD alternates between slow- and medium-paced modes every 3 and 40 ms, respectively. We also find that enHD binds nucleosomes and does so with enhanced affinity relative to naked DNA. Our results demonstrate that pioneer-like transcription factors can in principle do both, target nucleosomes and scan active DNA efficiently. The hybrid scanning mechanism used by enHD appears particularly well suited for the highly complex genomic signals of eukaryotic cells.
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Affiliation(s)
- Rama Reddy Goluguri
- CREST Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA 95343, USA
- Department of Bioengineering, University of California Merced, Merced, CA 95343, USA
| | - Catherine Ghosh
- CREST Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA 95343, USA
- Department of Bioengineering, University of California Merced, Merced, CA 95343, USA
| | - Joshua Quintong
- CREST Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA 95343, USA
- Department of Bioengineering, University of California Merced, Merced, CA 95343, USA
| | - Mourad Sadqi
- CREST Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA 95343, USA
- Department of Bioengineering, University of California Merced, Merced, CA 95343, USA
| | - Victor Muñoz
- CREST Center for Cellular and Biomolecular Machines, University of California Merced, Merced, CA 95343, USA
- Department of Bioengineering, University of California Merced, Merced, CA 95343, USA
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2
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Dhillon N, Kamakaka RT. Transcriptional silencing in Saccharomyces cerevisiae: known unknowns. Epigenetics Chromatin 2024; 17:28. [PMID: 39272151 PMCID: PMC11401328 DOI: 10.1186/s13072-024-00553-7] [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: 07/02/2024] [Accepted: 09/02/2024] [Indexed: 09/15/2024] Open
Abstract
Transcriptional silencing in Saccharomyces cerevisiae is a persistent and highly stable form of gene repression. It involves DNA silencers and repressor proteins that bind nucleosomes. The silenced state is influenced by numerous factors including the concentration of repressors, nature of activators, architecture of regulatory elements, modifying enzymes and the dynamics of chromatin.Silencers function to increase the residence time of repressor Sir proteins at silenced domains while clustering of silenced domains enables increased concentrations of repressors and helps facilitate long-range interactions. The presence of an accessible NDR at the regulatory regions of silenced genes, the cycling of chromatin configurations at regulatory sites, the mobility of Sir proteins, and the non-uniform distribution of the Sir proteins across the silenced domain, all result in silenced chromatin that only stably silences weak promoters and enhancers via changes in transcription burst duration and frequency.These data collectively suggest that silencing is probabilistic and the robustness of silencing is achieved through sub-optimization of many different nodes of action such that a stable expression state is generated and maintained even though individual constituents are in constant flux.
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Affiliation(s)
- Namrita Dhillon
- Department of Biomolecular Engineering, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA
| | - Rohinton T Kamakaka
- Department of MCD Biology, University of California, 1156 High Street, Santa Cruz, CA, 95064, USA.
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3
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Seitz H. A new perspective on microRNA-guided gene regulation specificity, and its potential generalization to transcription factors and RNA-binding proteins. Nucleic Acids Res 2024; 52:9360-9368. [PMID: 39149906 PMCID: PMC11381331 DOI: 10.1093/nar/gkae694] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2024] [Revised: 07/25/2024] [Accepted: 07/31/2024] [Indexed: 08/17/2024] Open
Abstract
Our conception of gene regulation specificity has undergone profound changes over the last 20 years. Previously, regulators were considered to control few genes, recognized with exquisite specificity by a 'lock and key' mechanism. However, recently genome-wide exploration of regulator binding site occupancy (whether on DNA or RNA targets) revealed extensive lists of molecular targets for every studied regulator. Such poor biochemical specificity suggested that each regulator controls many genes, collectively contributing to biological phenotypes. Here, I propose a third model, whereby regulators' biological specificity is only partially due to 'lock and key' biochemistry. Rather, regulators affect many genes at the microscopic scale, but biological consequences for most interactions are attenuated at the mesoscopic scale: only a few regulatory events propagate from microscopic to macroscopic scale; others are made inconsequential by homeostatic mechanisms. This model is well supported by the microRNA literature, and data suggest that it extends to other regulators. It reconciles contradicting observations from biochemistry and comparative genomics on one hand and in vivo genetics on the other hand, but this conceptual unification is obscured by common misconceptions and counter-intuitive modes of graphical display. Profound understanding of gene regulation requires conceptual clarification, and better suited statistical analyses and graphical representation.
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Affiliation(s)
- Hervé Seitz
- Institut de Génétique Humaine (UMR 9002), CNRS, 141, rue de la Cardonille, 34396 Montpellier, France
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4
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Yeo S, Jang J, Jung HJ, Lee H, Lee S, Choe Y. A Zwitterionic Detergent and Catalyst-Based Single-Cell Proteomics Using a Loss-Free Microhole-Collection Disc. Anal Chem 2024; 96:11690-11698. [PMID: 38991018 DOI: 10.1021/acs.analchem.4c00158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
Recent advances in single-cell proteomics have solved many bottlenecks, such as throughput, sample recovery, and scalability via nanoscale sample handling. In this study, we aimed for a sensitive mass spectrometry (MS) analysis capable of handling single cells with a conventional mass spectrometry workflow without additional equipment. We achieved seamless cell lysis and TMT labeling in a micro-HOLe Disc (microHOLD) by developing a mass-compatible single solution based on a zwitterionic detergent and a catalyst for single-cell lysis and tandem mass tag labeling without a heat incubation step. This method was developed to avoid peptide loss by surface adsorption and buffer or tube changes by collecting tandem mass tag-labeled peptide through microholes placed in the liquid chromatography injection vials in a single solution. We successfully applied the microHOLD single-cell proteomics method for the analysis of proteome reprogramming in hormone-sensitive prostate cells to develop castration-resistant prostate cancer cells. This novel single-cell proteomics method is not limited by cutting-edge nanovolume handling equipment and achieves high throughput and ultrasensitive proteomics analysis of limited samples, such as single cells.
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Affiliation(s)
- Seungeun Yeo
- Developmental disorders & rare diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Jaemyung Jang
- Developmental disorders & rare diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Hyun Jin Jung
- Developmental disorders & rare diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
| | - Hyeyoung Lee
- Division of Applied Bioengineering, Dong-Eui University, Busan 47340, Republic of Korea
| | - Sangkyu Lee
- School of Pharmacy, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Youngshik Choe
- Developmental disorders & rare diseases Research Group, Korea Brain Research Institute, Daegu 41062, Republic of Korea
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5
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Gourisankar S, Krokhotin A, Wenderski W, Crabtree GR. Context-specific functions of chromatin remodellers in development and disease. Nat Rev Genet 2024; 25:340-361. [PMID: 38001317 DOI: 10.1038/s41576-023-00666-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/27/2023] [Indexed: 11/26/2023]
Abstract
Chromatin remodellers were once thought to be highly redundant and nonspecific in their actions. However, recent human genetic studies demonstrate remarkable biological specificity and dosage sensitivity of the thirty-two adenosine triphosphate (ATP)-dependent chromatin remodellers encoded in the human genome. Mutations in remodellers produce many human developmental disorders and cancers, motivating efforts to investigate their distinct functions in biologically relevant settings. Exquisitely specific biological functions seem to be an emergent property in mammals, and in many cases are based on the combinatorial assembly of subunits and the generation of stable, composite surfaces. Critical interactions between remodelling complex subunits, the nucleosome and other transcriptional regulators are now being defined from structural and biochemical studies. In addition, in vivo analyses of remodellers at relevant genetic loci have provided minute-by-minute insights into their dynamics. These studies are proposing new models for the determinants of remodeller localization and function on chromatin.
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Affiliation(s)
- Sai Gourisankar
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Chemical Engineering, Stanford University, Stanford, CA, USA
| | - Andrey Krokhotin
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Wendy Wenderski
- Department of Pathology, Stanford University, Stanford, CA, USA
- Department of Developmental Biology, Stanford University, Stanford, CA, USA
| | - Gerald R Crabtree
- Department of Pathology, Stanford University, Stanford, CA, USA.
- Department of Developmental Biology, Stanford University, Stanford, CA, USA.
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6
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Saotome M, Poduval D, Grimm SA, Nagornyuk A, Gunarathna S, Shimbo T, Wade P, Takaku M. Genomic transcription factor binding site selection is edited by the chromatin remodeling factor CHD4. Nucleic Acids Res 2024; 52:3607-3622. [PMID: 38281186 PMCID: PMC11039999 DOI: 10.1093/nar/gkae025] [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: 05/27/2023] [Revised: 12/19/2023] [Accepted: 01/04/2024] [Indexed: 01/30/2024] Open
Abstract
Biologically precise enhancer licensing by lineage-determining transcription factors enables activation of transcripts appropriate to biological demand and prevents deleterious gene activation. This essential process is challenged by the millions of matches to most transcription factor binding motifs present in many eukaryotic genomes, leading to questions about how transcription factors achieve the exquisite specificity required. The importance of chromatin remodeling factors to enhancer activation is highlighted by their frequent mutation in developmental disorders and in cancer. Here, we determine the roles of CHD4 in enhancer licensing and maintenance in breast cancer cells and during cellular reprogramming. In unchallenged basal breast cancer cells, CHD4 modulates chromatin accessibility. Its depletion leads to redistribution of transcription factors to previously unoccupied sites. During cellular reprogramming induced by the pioneer factor GATA3, CHD4 activity is necessary to prevent inappropriate chromatin opening. Mechanistically, CHD4 promotes nucleosome positioning over GATA3 binding motifs to compete with transcription factor-DNA interaction. We propose that CHD4 acts as a chromatin proof-reading enzyme that prevents unnecessary gene expression by editing chromatin binding activities of transcription factors.
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Affiliation(s)
- Mika Saotome
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Deepak B Poduval
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Sara A Grimm
- Biostatistics and Computational Biology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Aerica Nagornyuk
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Sakuntha Gunarathna
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
| | - Takashi Shimbo
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Paul A Wade
- Epigenetics and Stem Cell Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
| | - Motoki Takaku
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, ND 58202, USA
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7
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Mulas C. Control of cell state transitions by post-transcriptional regulation. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230050. [PMID: 38432322 PMCID: PMC10909504 DOI: 10.1098/rstb.2023.0050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 12/19/2023] [Indexed: 03/05/2024] Open
Abstract
Cell state transitions are prevalent in biology, playing a fundamental role in development, homeostasis and repair. Dysregulation of cell state transitions can lead to or occur in a wide range of diseases. In this letter, I explore and highlight the role of post-transcriptional regulatory mechanisms in determining the dynamics of cell state transitions. I propose that regulation of protein levels after transcription provides an under-appreciated regulatory route to obtain fast and sharp transitions between distinct cell states. This article is part of a discussion meeting issue 'Causes and consequences of stochastic processes in development and disease'.
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Affiliation(s)
- Carla Mulas
- Altos Labs Cambridge Institute of Science, Granta Park, Cambridge, CB21 6GP, UK
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8
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Jia L, Gao S, Qiao Y. Optical Control over Liquid–Liquid Phase Separation. SMALL METHODS 2024:e2301724. [PMID: 38530063 DOI: 10.1002/smtd.202301724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Revised: 03/12/2024] [Indexed: 03/27/2024]
Abstract
Liquid-liquid phase separation (LLPS) is responsible for the emergence of intracellular membrane-less organelles and the development of coacervate protocells. Benefitting from the advantages of simplicity, precision, programmability, and noninvasiveness, light has become an effective tool to regulate the assembly dynamics of LLPS, and mediate various biochemical processes associated with LLPS. In this review, recent advances in optically controlling membrane-less organelles within living organisms are summarized, thereby modulating a series of biological processes including irreversible protein aggregation pathologies, transcription activation, metabolic flux, genomic rearrangements, and enzymatic reactions. Among these, the intracellular systems (i.e., optoDroplet, Corelet, PixELL, CasDrop, and other optogenetic systems) that enable the photo-mediated control over biomolecular condensation are highlighted. The design of photoactive complex coacervate protocells in laboratory settings by utilizing photochromic molecules such as azobenzene and diarylethene is further discussed. This review is expected to provide in-depth insights into phase separation-associated biochemical processes, bio-metabolism, and diseases.
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Affiliation(s)
- Liyan Jia
- Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Shan Gao
- Department of Orthopedic, Peking University Third Hospital, Beijing, 100191, China
| | - Yan Qiao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Laboratory of Polymer Physics and Chemistry, CAS Research/Education Center for Excellence in Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
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9
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Gan P, Eppert M, De La Cruz N, Lyons H, Shah AM, Veettil RT, Chen K, Pradhan P, Bezprozvannaya S, Xu L, Liu N, Olson EN, Sabari BR. Coactivator condensation drives cardiovascular cell lineage specification. SCIENCE ADVANCES 2024; 10:eadk7160. [PMID: 38489358 PMCID: PMC10942106 DOI: 10.1126/sciadv.adk7160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 02/12/2024] [Indexed: 03/17/2024]
Abstract
During development, cells make switch-like decisions to activate new gene programs specifying cell lineage. The mechanisms underlying these decisive choices remain unclear. Here, we show that the cardiovascular transcriptional coactivator myocardin (MYOCD) activates cell identity genes by concentration-dependent and switch-like formation of transcriptional condensates. MYOCD forms such condensates and activates cell identity genes at critical concentration thresholds achieved during smooth muscle cell and cardiomyocyte differentiation. The carboxyl-terminal disordered region of MYOCD is necessary and sufficient for condensate formation. Disrupting this region's ability to form condensates disrupts gene activation and smooth muscle cell reprogramming. Rescuing condensate formation by replacing this region with disordered regions from functionally unrelated proteins rescues gene activation and smooth muscle cell reprogramming. Our findings demonstrate that MYOCD condensate formation is required for gene activation during cardiovascular differentiation. We propose that the formation of transcriptional condensates at critical concentrations of cell type-specific regulators provides a molecular switch underlying the activation of key cell identity genes during development.
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Affiliation(s)
- Peiheng Gan
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Mikayla Eppert
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Nancy De La Cruz
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Heankel Lyons
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Akansha M. Shah
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Reshma T. Veettil
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Kenian Chen
- Quantitative Biomedical Research Center, Peter O’Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Prashant Pradhan
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Svetlana Bezprozvannaya
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Lin Xu
- Quantitative Biomedical Research Center, Peter O’Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Ning Liu
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Eric N. Olson
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Benjamin R. Sabari
- Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
- Laboratory of Nuclear Organization, Cecil H. and Ida Green Center for Reproductive Biology Sciences, Division of Basic Research, Department of Obstetrics and Gynecology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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10
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Haroush N, Levo M, Wieschaus EF, Gregor T. Functional analysis of the Drosophila eve locus in response to non-canonical combinations of gap gene expression levels. Dev Cell 2023; 58:2789-2801.e5. [PMID: 37890488 PMCID: PMC10872916 DOI: 10.1016/j.devcel.2023.10.001] [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: 11/03/2022] [Revised: 08/10/2023] [Accepted: 10/04/2023] [Indexed: 10/29/2023]
Abstract
Transcription factor combinations play a key role in shaping cellular identity. However, the precise relationship between specific combinations and downstream effects remains elusive. Here, we investigate this relationship within the context of the Drosophila eve locus, which is controlled by gap genes. We measure spatiotemporal levels of four gap genes in heterozygous and homozygous gap mutant embryos and correlate them with the striped eve activity pattern. Although changes in gap gene expression extend beyond the manipulated gene, the spatial patterns of Eve expression closely mirror canonical activation levels in wild type. Interestingly, some combinations deviate from the wild-type repertoire but still drive eve activation. Although in homozygous mutants some Eve stripes exhibit partial penetrance, stripes consistently emerge at reproducible positions, even with varying gap gene levels. Our findings suggest a robust molecular canalization of cell fates in gap mutants and provide insights into the regulatory constraints governing multi-enhancer gene loci.
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Affiliation(s)
- Netta Haroush
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Michal Levo
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA
| | - Eric F Wieschaus
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Department of Molecular Biology and Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA
| | - Thomas Gregor
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, NJ 08544, USA; Joseph Henry Laboratories of Physics, Princeton University, Princeton, NJ 08544, USA; Department of Stem Cell and Developmental Biology, CNRS UMR3738 Paris Cité, Institut Pasteur, 75015 Paris, France.
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11
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Feng M, Wang J, Li K, Nakamura F. UBE2A/B is the trans-acting factor mediating mechanotransduction and contact inhibition. Biochem J 2023; 480:1659-1674. [PMID: 37818922 DOI: 10.1042/bcj20230208] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/05/2023] [Accepted: 10/11/2023] [Indexed: 10/13/2023]
Abstract
Mechanotransduction and contact inhibition (CI) control gene expression to regulate proliferation, differentiation, and even tumorigenesis of cells. However, their downstream trans-acting factors (TAFs) are not well known due to a lack of a high-throughput method to quantitatively detect them. Here, we developed a method to identify TAFs on the cis-acting sequences that reside in open chromatin or DNaseI-hypersensitive sites (DHSs) and to detect nucleocytoplasmic shuttling TAFs using computational and experimental screening. The DHS-proteomics revealed over 1000 potential mechanosensing TAFs and UBE2A/B (Ubiquitin-conjugating enzyme E2 A) was experimentally identified as a force- and CI-dependent nucleocytoplasmic shuttling TAF. We found that translocation of YAP/TAZ and UBE2A/B are distinctively regulated by inhibition of myosin contraction, actin-polymerization, and CI depending on cell types. Next-generation sequence analysis revealed many downstream genes including YAP are transcriptionally regulated by ubiquitination of histone by UBE2A/B. Our results suggested a YAP-independent mechanotransduction and CI pathway mediated by UBE2A/B.
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Affiliation(s)
- Mingwei Feng
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Jiale Wang
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Kangjing Li
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
| | - Fumihiko Nakamura
- School of Pharmaceutical Science and Technology, Tianjin University, 92 Weijin Road, Nankai District, Tianjin 300072, China
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12
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Kind L, Driver M, Raasakka A, Onck PR, Njølstad PR, Arnesen T, Kursula P. Structural properties of the HNF-1A transactivation domain. Front Mol Biosci 2023; 10:1249939. [PMID: 37908230 PMCID: PMC10613711 DOI: 10.3389/fmolb.2023.1249939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Accepted: 09/26/2023] [Indexed: 11/02/2023] Open
Abstract
Hepatocyte nuclear factor 1α (HNF-1A) is a transcription factor with important gene regulatory roles in pancreatic β-cells. HNF1A gene variants are associated with a monogenic form of diabetes (HNF1A-MODY) or an increased risk for type 2 diabetes. While several pancreatic target genes of HNF-1A have been described, a lack of knowledge regarding the structure-function relationships in HNF-1A prohibits a detailed understanding of HNF-1A-mediated gene transcription, which is important for precision medicine and improved patient care. Therefore, we aimed to characterize the understudied transactivation domain (TAD) of HNF-1A in vitro. We present a bioinformatic approach to dissect the TAD sequence, analyzing protein structure, sequence composition, sequence conservation, and the existence of protein interaction motifs. Moreover, we developed the first protocol for the recombinant expression and purification of the HNF-1A TAD. Small-angle X-ray scattering and synchrotron radiation circular dichroism suggested a disordered conformation for the TAD. Furthermore, we present functional data on HNF-1A undergoing liquid-liquid phase separation, which is in line with in silico predictions and may be of biological relevance for gene transcriptional processes in pancreatic β-cells.
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Affiliation(s)
- Laura Kind
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Mark Driver
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Arne Raasakka
- Department of Biomedicine, University of Bergen, Bergen, Norway
| | - Patrick R. Onck
- Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Pål Rasmus Njølstad
- Mohn Center for Diabetes Precision Medicine, Department of Clinical Science, University of Bergen, Bergen, Norway
- Section of Endocrinology and Metabolism, Children and Youth Clinic, Haukeland University Hospital, Bergen, Norway
| | - Thomas Arnesen
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Department of Surgery, Haukeland University Hospital, Bergen, Norway
| | - Petri Kursula
- Department of Biomedicine, University of Bergen, Bergen, Norway
- Faculty of Biochemistry and Molecular Medicine & Biocenter Oulu, University of Oulu, Oulu, Finland
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13
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Azevedo-Pouly A, Hale MA, Swift GH, Hoang CQ, Deering TG, Xue J, Wilkie TM, Murtaugh LC, MacDonald RJ. Key transcriptional effectors of the pancreatic acinar phenotype and oncogenic transformation. PLoS One 2023; 18:e0291512. [PMID: 37796967 PMCID: PMC10553828 DOI: 10.1371/journal.pone.0291512] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 08/30/2023] [Indexed: 10/07/2023] Open
Abstract
Proper maintenance of mature cellular phenotypes is essential for stable physiology, suppression of disease states, and resistance to oncogenic transformation. We describe the transcriptional regulatory roles of four key DNA-binding transcription factors (Ptf1a, Nr5a2, Foxa2 and Gata4) that sit at the top of a regulatory hierarchy controlling all aspects of a highly differentiated cell-type-the mature pancreatic acinar cell (PAC). Selective inactivation of Ptf1a, Nr5a2, Foxa2 and Gata4 individually in mouse adult PACs rapidly altered the transcriptome and differentiation status of PACs. The changes most emphatically included transcription of the genes for the secretory digestive enzymes (which conscript more than 90% of acinar cell protein synthesis), a potent anabolic metabolism that provides the energy and materials for protein synthesis, suppressed and properly balanced cellular replication, and susceptibility to transformation by oncogenic KrasG12D. The simultaneous inactivation of Foxa2 and Gata4 caused a greater-than-additive disruption of gene expression and uncovered their collaboration to maintain Ptf1a expression and control PAC replication. A measure of PAC dedifferentiation ranked the effects of the conditional knockouts as Foxa2+Gata4 > Ptf1a > Nr5a2 > Foxa2 > Gata4. Whereas the loss of Ptf1a or Nr5a2 greatly accelerated Kras-mediated transformation of mature acinar cells in vivo, the absence of Foxa2, Gata4, or Foxa2+Gata4 together blocked transformation completely, despite extensive dedifferentiation. A lack of correlation between PAC dedifferentiation and sensitivity to oncogenic KrasG12D negates the simple proposition that the level of differentiation determines acinar cell resistance to transformation.
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Affiliation(s)
- Ana Azevedo-Pouly
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Michael A. Hale
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Galvin H. Swift
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Chinh Q. Hoang
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Tye G. Deering
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Jumin Xue
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Thomas M. Wilkie
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - L. Charles Murtaugh
- Department of Human Genetics, University of Utah, Salt Lake City, Utah, United States of America
| | - Raymond J. MacDonald
- Department of Molecular Biology and the Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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14
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Weiner L, Brissette JL. Finding meaning in chaos: a selection signature for functional interactions and its use in molecular biology. FEBS J 2023; 290:3914-3927. [PMID: 35653424 DOI: 10.1111/febs.16542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 04/18/2022] [Accepted: 06/01/2022] [Indexed: 11/28/2022]
Abstract
A primary goal of biomedical research is to elucidate molecular mechanisms, particularly those responsible for human traits, either normal or pathological. Yet achieving this goal is difficult if not impossible when the traits of interest lack tractable models and so cannot be dissected through time-honoured approaches like forward genetics or reconstitution. Arguably, no biological problem has hindered scientific progress more than this: the inability to dissect a trait's mechanism without a tractable likeness of the trait. At root, forward genetics and reconstitution are powerful approaches because they assay for specific molecular functions. Here, we discuss an alternative way to uncover important mechanistic interactions, namely, to assay for positive natural selection. If an interaction has been selected for, then it must perform an important function, a function that significantly promotes reproductive success. Accordingly, selection is a consequence and indicator of function, and uncovering multimolecular selection will reveal important functional interactions. We propose a selection signature for interactions and review recent selection-based approaches through which to dissect traits that are not inherently tractable. The review includes proof-of-principle studies in which important interactions were uncovered by screening for selection. In sum, screens for selection appear feasible when screens for specific functions are not. Selection screens thus constitute a novel tool through which to reveal the mechanisms that shape the fates of organisms.
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Affiliation(s)
- Lorin Weiner
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
| | - Janice L Brissette
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
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15
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Losa M, Barozzi I, Osterwalder M, Hermosilla-Aguayo V, Morabito A, Chacón BH, Zarrineh P, Girdziusaite A, Benazet JD, Zhu J, Mackem S, Capellini TD, Dickel D, Bobola N, Zuniga A, Visel A, Zeller R, Selleri L. A spatio-temporally constrained gene regulatory network directed by PBX1/2 acquires limb patterning specificity via HAND2. Nat Commun 2023; 14:3993. [PMID: 37414772 PMCID: PMC10325989 DOI: 10.1038/s41467-023-39443-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/14/2023] [Indexed: 07/08/2023] Open
Abstract
A lingering question in developmental biology has centered on how transcription factors with widespread distribution in vertebrate embryos can perform tissue-specific functions. Here, using the murine hindlimb as a model, we investigate the elusive mechanisms whereby PBX TALE homeoproteins, viewed primarily as HOX cofactors, attain context-specific developmental roles despite ubiquitous presence in the embryo. We first demonstrate that mesenchymal-specific loss of PBX1/2 or the transcriptional regulator HAND2 generates similar limb phenotypes. By combining tissue-specific and temporally controlled mutagenesis with multi-omics approaches, we reconstruct a gene regulatory network (GRN) at organismal-level resolution that is collaboratively directed by PBX1/2 and HAND2 interactions in subsets of posterior hindlimb mesenchymal cells. Genome-wide profiling of PBX1 binding across multiple embryonic tissues further reveals that HAND2 interacts with subsets of PBX-bound regions to regulate limb-specific GRNs. Our research elucidates fundamental principles by which promiscuous transcription factors cooperate with cofactors that display domain-restricted localization to instruct tissue-specific developmental programs.
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Affiliation(s)
- Marta Losa
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Iros Barozzi
- Center for Cancer Research, Medical University of Vienna, Vienna, Austria
| | - Marco Osterwalder
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- Department for Biomedical Research (DBMR), University of Bern, Bern, Switzerland
- Department of Cardiology, Bern University Hospital, Bern, Switzerland
| | - Viviana Hermosilla-Aguayo
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Angela Morabito
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Brandon H Chacón
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Peyman Zarrineh
- School of Medical Sciences, University of Manchester, Manchester, UK
| | - Ausra Girdziusaite
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Jean Denis Benazet
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA
| | - Jianjian Zhu
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Susan Mackem
- Cancer and Developmental Biology Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD, USA
| | - Terence D Capellini
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Diane Dickel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Nicoletta Bobola
- School of Medical Sciences, University of Manchester, Manchester, UK
| | - Aimée Zuniga
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Axel Visel
- Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
- US Department of Energy Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- School of Natural Sciences, University of California, Merced, Merced, CA, 95343, USA
| | - Rolf Zeller
- Developmental Genetics, Department Biomedicine, University of Basel, Basel, Switzerland
| | - Licia Selleri
- Program in Craniofacial Biology, Institute for Human Genetics, Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Department of Orofacial Sciences and Department of Anatomy, University of California San Francisco, San Francisco, CA, USA.
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16
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Tang Y, Aryal S, Geng X, Zhou X, Fast VG, Zhang J, Lu R, Zhou Y. TBX20 Improves Contractility and Mitochondrial Function During Direct Human Cardiac Reprogramming. Circulation 2022; 146:1518-1536. [PMID: 36102189 PMCID: PMC9662826 DOI: 10.1161/circulationaha.122.059713] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Direct cardiac reprogramming of fibroblasts into cardiomyocytes has emerged as a promising strategy to remuscularize injured myocardium. However, it is insufficient to generate functional induced cardiomyocytes from human fibroblasts using conventional reprogramming cocktails, and the underlying molecular mechanisms are not well studied. METHODS To discover potential missing factors for human direct reprogramming, we performed transcriptomic comparison between human induced cardiomyocytes and functional cardiomyocytes. RESULTS We identified TBX20 (T-box transcription factor 20) as the top cardiac gene that is unable to be activated by the MGT133 reprogramming cocktail (MEF2C, GATA4, TBX5, and miR-133). TBX20 is required for normal heart development and cardiac function in adult cardiomyocytes, yet its role in cardiac reprogramming remains undefined. We show that the addition of TBX20 to the MGT133 cocktail (MGT+TBX20) promotes cardiac reprogramming and activates genes associated with cardiac contractility, maturation, and ventricular heart. Human induced cardiomyocytes produced with MGT+TBX20 demonstrated more frequent beating, calcium oscillation, and higher energy metabolism as evidenced by increased mitochondria numbers and mitochondrial respiration. Mechanistically, comprehensive transcriptomic, chromatin occupancy, and epigenomic studies revealed that TBX20 colocalizes with MGT reprogramming factors at cardiac gene enhancers associated with heart contraction, promotes chromatin binding and co-occupancy of MGT factors at these loci, and synergizes with MGT for more robust activation of target gene transcription. CONCLUSIONS TBX20 consolidates MGT cardiac reprogramming factors to activate cardiac enhancers to promote cardiac cell fate conversion. Human induced cardiomyocytes generated with TBX20 showed enhanced cardiac function in contractility and mitochondrial respiration.
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Affiliation(s)
- Yawen Tang
- Department of Biomedical Engineering (Y.T., X.G., V.G.F., J.Z., Y.Z.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Sajesan Aryal
- Department of Medicine, Division of Hematology and Oncology (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham.,O’Neal Comprehensive Cancer Center (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Xiaoxiao Geng
- Department of Biomedical Engineering (Y.T., X.G., V.G.F., J.Z., Y.Z.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Xinyue Zhou
- Department of Medicine, Division of Hematology and Oncology (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham.,O’Neal Comprehensive Cancer Center (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Vladimir G. Fast
- Department of Biomedical Engineering (Y.T., X.G., V.G.F., J.Z., Y.Z.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Jianyi Zhang
- Department of Biomedical Engineering (Y.T., X.G., V.G.F., J.Z., Y.Z.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Rui Lu
- Department of Medicine, Division of Hematology and Oncology (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham.,O’Neal Comprehensive Cancer Center (S.A., X.Z., R.L.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
| | - Yang Zhou
- Department of Biomedical Engineering (Y.T., X.G., V.G.F., J.Z., Y.Z.), Heersink School of Medicine, School of Engineering, University of Alabama at Birmingham
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17
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Zhang X, Zeng Y. Relative specificity as an important consideration in the big data era. Front Genet 2022; 13:1030415. [DOI: 10.3389/fgene.2022.1030415] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 09/20/2022] [Indexed: 11/13/2022] Open
Abstract
Technological breakthroughs such as high-throughput methods, genomics, single-cell studies, and machine learning have fundamentally transformed research and ushered in the big data era of biology. Nevertheless, current data collections, analyses, and modeling frequently overlook relative specificity, a crucial property of molecular interactions in biochemical systems. Relative specificity describes how, for example, an enzyme reacts with its many substrates at different rates, and how this discriminatory action alone is sufficient to modulate the substrates and downstream events. As a corollary, it is not only important to comprehensively identify an enzyme’s substrates, but also critical to quantitatively determine how the enzyme interacts with the substrates and to evaluate how it shapes subsequent biological outcomes. Genomics and high-throughput techniques have greatly facilitated the studies of relative specificity in the 21st century, and its functional significance has been demonstrated in complex biochemical systems including transcription, translation, protein kinases, RNA-binding proteins, and animal microRNAs (miRNAs), although it remains ignored in most work. Here we analyze recent findings in big data and relative specificity studies and explain how the incorporation of relative specificity concept might enhance our mechanistic understanding of gene functions, biological phenomena, and human diseases.
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18
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Shahein A, López-Malo M, Istomin I, Olson EJ, Cheng S, Maerkl SJ. Systematic analysis of low-affinity transcription factor binding site clusters in vitro and in vivo establishes their functional relevance. Nat Commun 2022; 13:5273. [PMID: 36071116 PMCID: PMC9452512 DOI: 10.1038/s41467-022-32971-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/25/2022] [Indexed: 11/10/2022] Open
Abstract
Binding to binding site clusters has yet to be characterized in depth, and the functional relevance of low-affinity clusters remains uncertain. We characterized transcription factor binding to low-affinity clusters in vitro and found that transcription factors can bind concurrently to overlapping sites, challenging the notion of binding exclusivity. Furthermore, small clusters with binding sites an order of magnitude lower in affinity give rise to high mean occupancies at physiologically-relevant transcription factor concentrations. To assess whether the observed in vitro occupancies translate to transcriptional activation in vivo, we tested low-affinity binding site clusters in a synthetic and native gene regulatory network in S. cerevisiae. In both systems, clusters of low-affinity binding sites generated transcriptional output comparable to single or even multiple consensus sites. This systematic characterization demonstrates that clusters of low-affinity binding sites achieve substantial occupancies, and that this occupancy can drive expression in eukaryotic promoters.
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Affiliation(s)
- Amir Shahein
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Maria López-Malo
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Ivan Istomin
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Evan J Olson
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Shiyu Cheng
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Sebastian J Maerkl
- Institute of Bioengineering, School of Engineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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19
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Graham TGW, Ferrie JJ, Dailey GM, Tjian R, Darzacq X. Detecting molecular interactions in live-cell single-molecule imaging with proximity-assisted photoactivation (PAPA). eLife 2022; 11:e76870. [PMID: 35976226 PMCID: PMC9531946 DOI: 10.7554/elife.76870] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
Single-molecule imaging provides a powerful way to study biochemical processes in live cells, yet it remains challenging to track single molecules while simultaneously detecting their interactions. Here, we describe a novel property of rhodamine dyes, proximity-assisted photoactivation (PAPA), in which one fluorophore (the 'sender') can reactivate a second fluorophore (the 'receiver') from a dark state. PAPA requires proximity between the two fluorophores, yet it operates at a longer average intermolecular distance than Förster resonance energy transfer (FRET). We show that PAPA can be used in live cells both to detect protein-protein interactions and to highlight a subpopulation of labeled protein complexes in which two different labels are in proximity. In proof-of-concept experiments, PAPA detected the expected correlation between androgen receptor self-association and chromatin binding at the single-cell level. These results establish a new way in which a photophysical property of fluorophores can be harnessed to study molecular interactions in single-molecule imaging of live cells.
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Affiliation(s)
- Thomas GW Graham
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - John Joseph Ferrie
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Gina M Dailey
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
- Howard Hughes Medical Institute, University of California, BerkeleyBerkeleyUnited States
| | - Xavier Darzacq
- Department of Molecular and Cell Biology, University of California, BerkeleyBerkeleyUnited States
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20
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Tsuji A, Yamashita H, Hisatomi O, Abe M. Dimerization processes for light-regulated transcription factor Photozipper visualized by high-speed atomic force microscopy. Sci Rep 2022; 12:12903. [PMID: 35941201 PMCID: PMC9359980 DOI: 10.1038/s41598-022-17228-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
Dimerization is critical for transcription factors (TFs) to bind DNA and regulate a wide variety of cellular functions; however, the molecular mechanisms remain to be completely elucidated. Here, we used high-speed atomic force microscopy (HS-AFM) to observe the dimerization process for a photoresponsive TF Photozipper (PZ), which consists of light–oxygen–voltage-sensing (LOV) and basic-region-leucine-zipper (bZIP) domains. HS-AFM visualized not only the oligomeric states of PZ molecules forming monomers and dimers under controlled dark–light conditions but also the domain structures within each molecule. Successive AFM movies captured the dimerization process for an individual PZ molecule and the monomer–dimer reversible transition during dark–light cycling. Detailed AFM images of domain structures in PZ molecules demonstrated that the bZIP domain entangled under dark conditions was loosened owing to light illumination and fluctuated around the LOV domain. These observations revealed the role of the bZIP domain in the dimerization processes of a TF.
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Affiliation(s)
- Akihiro Tsuji
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Hayato Yamashita
- Graduate School of Engineering Science, Osaka University, Osaka, Japan.
| | - Osamu Hisatomi
- Graduate School of Science, Osaka University, Osaka, Japan
| | - Masayuki Abe
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
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21
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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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22
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Winkler S, Winkler I, Figaschewski M, Tiede T, Nordheim A, Kohlbacher O. De novo identification of maximally deregulated subnetworks based on multi-omics data with DeRegNet. BMC Bioinformatics 2022; 23:139. [PMID: 35439941 PMCID: PMC9020058 DOI: 10.1186/s12859-022-04670-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Accepted: 03/29/2022] [Indexed: 12/14/2022] Open
Abstract
Background With a growing amount of (multi-)omics data being available, the extraction of knowledge from these datasets is still a difficult problem. Classical enrichment-style analyses require predefined pathways or gene sets that are tested for significant deregulation to assess whether the pathway is functionally involved in the biological process under study. De novo identification of these pathways can reduce the bias inherent in predefined pathways or gene sets. At the same time, the definition and efficient identification of these pathways de novo from large biological networks is a challenging problem. Results We present a novel algorithm, DeRegNet, for the identification of maximally deregulated subnetworks on directed graphs based on deregulation scores derived from (multi-)omics data. DeRegNet can be interpreted as maximum likelihood estimation given a certain probabilistic model for de-novo subgraph identification. We use fractional integer programming to solve the resulting combinatorial optimization problem. We can show that the approach outperforms related algorithms on simulated data with known ground truths. On a publicly available liver cancer dataset we can show that DeRegNet can identify biologically meaningful subgraphs suitable for patient stratification. DeRegNet can also be used to find explicitly multi-omics subgraphs which we demonstrate by presenting subgraphs with consistent methylation-transcription patterns. DeRegNet is freely available as open-source software. Conclusion The proposed algorithmic framework and its available implementation can serve as a valuable heuristic hypothesis generation tool contextualizing omics data within biomolecular networks.
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Affiliation(s)
- Sebastian Winkler
- Applied Bioinformatics, Department of Computer Science, University of Tuebingen, Tübingen, Germany. .,International Max Planck Research School (IMPRS) "From Molecules to Organism", Tübingen, Germany.
| | - Ivana Winkler
- International Max Planck Research School (IMPRS) "From Molecules to Organism", Tübingen, Germany.,Interfaculty Institute for Cell Biology (IFIZ), University of Tuebingen, Tübingen, Germany.,German Cancer Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Mirjam Figaschewski
- Applied Bioinformatics, Department of Computer Science, University of Tuebingen, Tübingen, Germany
| | - Thorsten Tiede
- Applied Bioinformatics, Department of Computer Science, University of Tuebingen, Tübingen, Germany
| | - Alfred Nordheim
- Interfaculty Institute for Cell Biology (IFIZ), University of Tuebingen, Tübingen, Germany.,Leibniz Institute on Aging (FLI), Jena, Germany
| | - Oliver Kohlbacher
- Applied Bioinformatics, Department of Computer Science, University of Tuebingen, Tübingen, Germany.,Institute for Bioinformatics and Medical Informatics, University of Tuebingen, Tübingen, Germany.,Translational Bioinformatics, University Hospital Tuebingen, Tübingen, Germany
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23
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Kreimer A, Ashuach T, Inoue F, Khodaverdian A, Deng C, Yosef N, Ahituv N. Massively parallel reporter perturbation assays uncover temporal regulatory architecture during neural differentiation. Nat Commun 2022; 13:1504. [PMID: 35315433 PMCID: PMC8938438 DOI: 10.1038/s41467-022-28659-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 02/04/2022] [Indexed: 02/08/2023] Open
Abstract
Gene regulatory elements play a key role in orchestrating gene expression during cellular differentiation, but what determines their function over time remains largely unknown. Here, we perform perturbation-based massively parallel reporter assays at seven early time points of neural differentiation to systematically characterize how regulatory elements and motifs within them guide cellular differentiation. By perturbing over 2,000 putative DNA binding motifs in active regulatory regions, we delineate four categories of functional elements, and observe that activity direction is mostly determined by the sequence itself, while the magnitude of effect depends on the cellular environment. We also find that fine-tuning transcription rates is often achieved by a combined activity of adjacent activating and repressing elements. Our work provides a blueprint for the sequence components needed to induce different transcriptional patterns in general and specifically during neural differentiation. How gene regulatory elements regulate gene expression during cellular differentiation remains largely unknown. Here the authors use perturbation-based massively parallel reporter assays at early time points of neural differentiation to systematically characterize how regulatory elements and motifs within them guide different transcriptional patterns.
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24
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Ulasov AV, Rosenkranz AA, Georgiev GP, Sobolev AS. Nrf2/Keap1/ARE signaling: Towards specific regulation. Life Sci 2022; 291:120111. [PMID: 34732330 PMCID: PMC8557391 DOI: 10.1016/j.lfs.2021.120111] [Citation(s) in RCA: 174] [Impact Index Per Article: 87.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 02/06/2023]
Abstract
The Nrf2 transcription factor governs the expression of hundreds genes involved in cell defense against oxidative stress, the hallmark of numerous diseases such as neurodegenerative, cardiovascular, some viral pathologies, diabetes and others. The main route for Nrf2 activity regulation is via interactions with the Keap1 protein. Under the normoxia the Keap1 binds the Nrf2 and targets it to the proteasomal degradation, while the Keap1 is regenerated. Upon oxidative stress the interactions between Nrf2 and Keap1 are interrupted and the Nrf2 activates the transcription of the protective genes. Currently, the Nrf2 system activation is considered as a powerful cytoprotective strategy for treatment of different pathologies, which pathogenesis relies on oxidative stress including viral diseases of pivotal importance such as COVID-19. The implementation of this strategy is accomplished mainly through the inactivation of the Keap1 "guardian" function. Two approaches are now developing: the Keap1 modification via electrophilic agents, which leads to the Nrf2 release, and direct interruption of the Nrf2:Keap1 protein-protein interactions (PPI). Because of theirs chemical structure, the Nrf2 electrophilic inducers could non-specifically interact with others cellular proteins leading to undesired effects. Whereas the non-electrophilic inhibitors of the Nrf2:Keap1 PPI could be more specific, thereby widening the therapeutic window.
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Affiliation(s)
- Alexey V Ulasov
- Department of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia.
| | - Andrey A Rosenkranz
- Department of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; Faculty of Biology, Moscow State University, 1-12 Leninskiye Gory St., 119234 Moscow, Russia
| | - Georgii P Georgiev
- Department of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia
| | - Alexander S Sobolev
- Department of Molecular Genetics of Intracellular Transport, Institute of Gene Biology, Russian Academy of Sciences, 34/5 Vavilov St., 119334 Moscow, Russia; Faculty of Biology, Moscow State University, 1-12 Leninskiye Gory St., 119234 Moscow, Russia
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25
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Shimai K, Veeman M. Quantitative Dissection of the Proximal Ciona brachyury Enhancer. Front Cell Dev Biol 2022; 9:804032. [PMID: 35127721 PMCID: PMC8814421 DOI: 10.3389/fcell.2021.804032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
A major goal in biology is to understand the rules by which cis-regulatory sequences control spatially and temporally precise expression patterns. Here we present a systematic dissection of the proximal enhancer for the notochord-specific transcription factor brachyury in the ascidian chordate Ciona. The study uses a quantitative image-based reporter assay that incorporates a dual-reporter strategy to control for variable electroporation efficiency. We identified and mutated multiple predicted transcription factor binding sites of interest based on statistical matches to the JASPAR binding motif database. Most sites (Zic, Ets, FoxA, RBPJ) were selected based on prior knowledge of cell fate specification in both the primary and secondary notochord. We also mutated predicted Brachyury sites to investigate potential autoregulation as well as Fos/Jun (AP1) sites that had very strong matches to JASPAR. Our goal was to quantitatively define the relative importance of these different sites, to explore the importance of predicted high-affinity versus low-affinity motifs, and to attempt to design mutant enhancers that were specifically expressed in only the primary or secondary notochord lineages. We found that the mutation of all predicted high-affinity sites for Zic, FoxA or Ets led to quantifiably distinct effects. The FoxA construct caused a severe loss of reporter expression whereas the Ets construct had little effect. A strong Ets phenotype was only seen when much lower-scoring binding sites were also mutated. This supports the enhancer suboptimization hypothesis proposed by Farley and Levine but suggests that it may only apply to some but not all transcription factor families. We quantified reporter expression separately in the two notochord lineages with the expectation that Ets mutations and RBPJ mutations would have distinct effects given that primary notochord is induced by Ets-mediated FGF signaling whereas secondary notochord is induced by RBPJ/Su(H)-mediated Notch/Delta signaling. We found, however, that ETS mutations affected primary and secondary notochord expression relatively equally and that RBPJ mutations were only moderately more severe in their effect on secondary versus primary notochord. Our results point to the promise of quantitative reporter assays for understanding cis-regulatory logic but also highlight the challenge of arbitrary statistical thresholds for predicting potentially important sites.
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26
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Zhang X, Yang F, Liu F, Tian Q, Hu M, Li P, Zeng Y. Conservation of Differential Animal MicroRNA Processing by Drosha and Dicer. Front Mol Biosci 2022; 8:730006. [PMID: 35047552 PMCID: PMC8761633 DOI: 10.3389/fmolb.2021.730006] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
In complex biochemical systems, an enzyme, protein, or RNA, symbolized as E, has hundreds or thousands of substrates or interacting partners. The relative specificity hypothesis proposes that such an E would differentially interact with and influence its many distinct, downstream substrates, thereby regulating the underlying biological process (es). The importance of relative specificity has been underappreciated, and evidence of its physiological consequences particularly lacking. Previously we showed that human Drosha and Dicer ribonucleases (RNases) both discriminate their respective microRNA (miRNA) substrates, and that differential cleavage by Drosha contributes to global differential miRNA expression. If relative specificity is an important biological mechanism, it should be evolutionarily conserved. To test this hypothesis, we hereby examined the cleavage of hundreds of zebrafish and fruitfly miRNA intermediates by Drosha and Dicer and the impact on miRNA biogenesis in these organisms. We showed that Drosha action regulates differential miRNA expression in zebrafish and fruitflies and identified the conserved secondary structure features and sequences in miRNA transcripts that control Drosha activity and miRNA expression. Our results established the conservation of miRNA processing mechanisms and regulatory functions by Drosha and Dicer, greatly strengthened the evidence for the physiological consequences of relative specificity as well as demonstrated its evolutionary significance.
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Affiliation(s)
- Xiaoxiao Zhang
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Fanming Yang
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Fanzou Liu
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Qiuhuan Tian
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Min Hu
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Peng Li
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
| | - Yan Zeng
- Department of Zoology, College of Life Sciences, Nanjing Agricultural University, Nanjing, China
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27
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Rothenberg EV. Transcription factors specifically control change. Genes Dev 2022; 36:1097-1099. [PMID: 36622807 PMCID: PMC9851400 DOI: 10.1101/gad.350308.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Transcription factors are defined by their sequence-specific binding to DNA and by their selective impacts on gene expression, depending on specific binding sites. The factor binding motifs in the DNA should thus represent a blueprint of regulatory logic, suggesting that transcription factor binding patterns on the genome (e.g., measured by ChIP-seq) should indicate which target genes the factors are directly controlling. However, although genetic data confirm high impacts of transcription factor perturbation in embryology, transcription factors bind to far more sites than the number of genes they dynamically regulate, when measured by direct perturbation in a given cell type. Also, deletion of carefully chosen transcription factor binding sites often gives disappointingly weak results. In a new study in the previous issue of Genes & Development, Lo and colleagues (pp. 1079-1095) reconcile these contradictions by using an elegant experimental system to directly compare the roles of transcription factor-binding site interaction in gene regulation maintenance with roles of the same factor-site interactions in gene regulation through developmental change. They examine Oct4:Sox2 shared target genes under maintained versus reinduced pluripotency conditions within the same cell clone. The results show that the same factor-site interaction impacts can appear modest in assays in developmental steady-state but are far more important as regulatory catalysts of developmental change.
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28
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González-Grandío E, Álamos S, Zhang Y, Dalton-Roesler J, Niyogi KK, García HG, Quail PH. Chromatin Changes in Phytochrome Interacting Factor-Regulated Genes Parallel Their Rapid Transcriptional Response to Light. FRONTIERS IN PLANT SCIENCE 2022; 13:803441. [PMID: 35251080 PMCID: PMC8891703 DOI: 10.3389/fpls.2022.803441] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 01/27/2022] [Indexed: 05/11/2023]
Abstract
As sessile organisms, plants must adapt to a changing environment, sensing variations in resource availability and modifying their development in response. Light is one of the most important resources for plants, and its perception by sensory photoreceptors (e.g., phytochromes) and subsequent transduction into long-term transcriptional reprogramming have been well characterized. Chromatin changes have been shown to be involved in photomorphogenesis. However, the initial short-term transcriptional changes produced by light and what factors enable these rapid changes are not well studied. Here, we define rapidly light-responsive, Phytochrome Interacting Factor (PIF) direct-target genes (LRP-DTGs). We found that a majority of these genes also show rapid changes in Histone 3 Lysine-9 acetylation (H3K9ac) in response to the light signal. Detailed time-course analysis of transcript and chromatin changes showed that, for light-repressed genes, H3K9 deacetylation parallels light-triggered transcriptional repression, while for light-induced genes, H3K9 acetylation appeared to somewhat precede light-activated transcript accumulation. However, direct, real-time imaging of transcript elongation in the nucleus revealed that, in fact, transcriptional induction actually parallels H3K9 acetylation. Collectively, the data raise the possibility that light-induced transcriptional and chromatin-remodeling processes are mechanistically intertwined. Histone modifying proteins involved in long term light responses do not seem to have a role in this fast response, indicating that different factors might act at different stages of the light response. This work not only advances our understanding of plant responses to light, but also unveils a system in which rapid chromatin changes in reaction to an external signal can be studied under natural conditions.
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Affiliation(s)
- Eduardo González-Grandío
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Plant Gene Expression Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, United States
- *Correspondence: Eduardo González-Grandío,
| | - Simón Álamos
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Feedstocks Division, Joint BioEnergy Institute, Emeryville, CA, United States
| | - Yu Zhang
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Plant Gene Expression Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, United States
| | - Jutta Dalton-Roesler
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Plant Gene Expression Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, United States
| | - Krishna K. Niyogi
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Howard Hughes Medical Institute, University of California, Berkeley, Berkeley, CA, United States
- Molecular Biophysics and Integrated Bioimaging Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States
| | - Hernán G. García
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, United States
- Department of Physics, University of California, Berkeley, Berkeley, CA, United States
- California Institute for Quantitative Biosciences (QB3), University of California, Berkeley, Berkeley, CA, United States
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA, United States
| | - Peter H. Quail
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA, United States
- Plant Gene Expression Center, Agricultural Research Service, US Department of Agriculture, Albany, CA, United States
- Peter H. Quail,
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29
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Three topological features of regulatory networks control life-essential and specialized subsystems. Sci Rep 2021; 11:24209. [PMID: 34930908 PMCID: PMC8688434 DOI: 10.1038/s41598-021-03625-w] [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] [Received: 03/10/2021] [Accepted: 12/07/2021] [Indexed: 11/08/2022] Open
Abstract
Gene regulatory networks (GRNs) play key roles in development, phenotype plasticity, and evolution. Although graph theory has been used to explore GRNs, associations amongst topological features, transcription factors (TFs), and systems essentiality are poorly understood. Here we sought the relationship amongst the main GRN topological features that influence the control of essential and specific subsystems. We found that the Knn, page rank, and degree are the most relevant GRN features: the ones are conserved along the evolution and are also relevant in pluripotent cells. Interestingly, life-essential subsystems are governed mainly by TFs with intermediary Knn and high page rank or degree, whereas specialized subsystems are mainly regulated by TFs with low Knn. Hence, we suggest that the high probability of TFs be toured by a random signal, and the high probability of the signal propagation to target genes ensures the life-essential subsystems' robustness. Gene/genome duplication is the main evolutionary process to rise Knn as the most relevant feature. Herein, we shed light on unexplored topological GRN features to assess how they are related to subsystems and how the duplications shaped the regulatory systems along the evolution. The classification model generated can be found here: https://github.com/ivanrwolf/NoC/ .
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30
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Cain B, Gebelein B. Mechanisms Underlying Hox-Mediated Transcriptional Outcomes. Front Cell Dev Biol 2021; 9:787339. [PMID: 34869389 PMCID: PMC8635045 DOI: 10.3389/fcell.2021.787339] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 10/28/2021] [Indexed: 11/13/2022] Open
Abstract
Metazoans differentially express multiple Hox transcription factors to specify diverse cell fates along the developing anterior-posterior axis. Two challenges arise when trying to understand how the Hox transcription factors regulate the required target genes for morphogenesis: First, how does each Hox factor differ from one another to accurately activate and repress target genes required for the formation of distinct segment and regional identities? Second, how can a Hox factor that is broadly expressed in many tissues within a segment impact the development of specific organs by regulating target genes in a cell type-specific manner? In this review, we highlight how recent genomic, interactome, and cis-regulatory studies are providing new insights into answering these two questions. Collectively, these studies suggest that Hox factors may differentially modify the chromatin of gene targets as well as utilize numerous interactions with additional co-activators, co-repressors, and sequence-specific transcription factors to achieve accurate segment and cell type-specific transcriptional outcomes.
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Affiliation(s)
- Brittany Cain
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States
| | - Brian Gebelein
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, United States.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, United States
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31
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Reduction in gene expression noise by targeted increase in accessibility at gene loci. Proc Natl Acad Sci U S A 2021; 118:2018640118. [PMID: 34625470 DOI: 10.1073/pnas.2018640118] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2021] [Indexed: 01/30/2023] Open
Abstract
Many eukaryotic genes are expressed in randomly initiated bursts that are punctuated by periods of quiescence. Here, we show that the intermittent access of the promoters to transcription factors through relatively impervious chromatin contributes to this "noisy" transcription. We tethered a nuclease-deficient Cas9 fused to a histone acetyl transferase at the promoters of two endogenous genes in HeLa cells. An assay for transposase-accessible chromatin using sequencing showed that the activity of the histone acetyl transferase altered the chromatin architecture locally without introducing global changes in the nucleus and rendered the targeted promoters constitutively accessible. We measured the gene expression variability from the gene loci by performing single-molecule fluorescence in situ hybridization against mature messenger RNAs (mRNAs) and by imaging nascent mRNA molecules present at active gene loci in single cells. Because of the increased accessibility of the promoter to transcription factors, the transcription from two genes became less noisy, even when the average levels of expression did not change. In addition to providing evidence for chromatin accessibility as a determinant of the noise in gene expression, our study offers a mechanism for controlling gene expression noise which is otherwise unavoidable.
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32
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Beskorovainaya TS, Zabnenkova VV, Zinchenko RA, Shchagina OA, Polyakov AV. Hemophilia B Leyden: Literature and Our Data. RUSS J GENET+ 2021. [DOI: 10.1134/s1022795421100033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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33
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Waymack R, Gad M, Wunderlich Z. Molecular competition can shape enhancer activity in the Drosophila embryo. iScience 2021; 24:103034. [PMID: 34568782 PMCID: PMC8449247 DOI: 10.1016/j.isci.2021.103034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/20/2021] [Indexed: 01/12/2023] Open
Abstract
Transgenic reporters allow the measurement of regulatory DNA activity in vivo and consequently have long been useful tools for studying enhancers. Despite their utility, few studies have investigated the effects these reporters may have on the expression of other genes. Understanding these effects is required to accurately interpret reporter data and characterize gene regulatory mechanisms. By measuring the expression of Kruppel (Kr) enhancer reporters in live Drosophila embryos, we find reporters inhibit one another's expression and that of a nearby endogenous gene. Using synthetic transcription factor (TF) binding site arrays, we present evidence that competition for TFs is partially responsible for the observed transcriptional inhibition. We develop a simple thermodynamic model that predicts competition of the measured magnitude specifically when TF binding is restricted to distinct nuclear subregions. Our findings underline an unexpected role of the non-homogenous nature of the nucleus in regulating gene expression.
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Affiliation(s)
- Rachel Waymack
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Mario Gad
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Zeba Wunderlich
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
- Department of Biology, Boston University, 610 Commonwealth Ave., Boston, MA 02215, USA
- Biological Design Center, Boston University, 610 Commonwealth Avenue, Boston, MA 02215, USA
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34
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Krebs AR. Studying transcription factor function in the genome at molecular resolution. Trends Genet 2021; 37:798-806. [DOI: 10.1016/j.tig.2021.03.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Revised: 03/22/2021] [Accepted: 03/23/2021] [Indexed: 12/11/2022]
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35
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Kałas W. Should Nano-Particles be Weighed or Counted? Technical Considerations to In Vitro Testing Originated from Corpuscular Nature of Nano-Particles. Arch Immunol Ther Exp (Warsz) 2021; 69:23. [PMID: 34345944 PMCID: PMC8332567 DOI: 10.1007/s00005-021-00623-8] [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: 02/22/2021] [Accepted: 06/26/2021] [Indexed: 12/05/2022]
Abstract
The abundance of nanoparticles introduced to household products created the great expectations towards the application of nanotechnology in biology and medicine. That calls for cost-effective preliminary assessment of its cytotoxicity and biological activity. There are many attempts for creating proper guidance and standards for performing studies regarding nanoparticles. But still some important aspects crucial for in vitro testing of nanomaterials need more attention. Particulate nature is an obvious and widely unappreciated property of nanoparticles. In the context of in vitro studies, this property is critical, and it should be, but rarely is, considered when designing, performing, describing or interpreting the experiments involving the solid nanoparticles. First, we should be aware of relatively small and limited number of nanoparticles in the experimental setup. Even crude estimation of its number will be useful for proper interpretation of results. Second, we should not presume even distribution of particles in the solution, moreover we should expect that sedimentation and aggregation play an important role in interactions of nanoparticles with cells. In that case, expressing the dose in mass/volume units may lead as astray. Finally, the relation of size, weight, and number of nanoparticles makes comparisons of activity of nanoparticles of different sizes very complex. Estimations of number of nanoparticles in the dose should be an integral part of experiment design, its validation and interpretation.
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Affiliation(s)
- Wojciech Kałas
- Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, 53-114, Wrocław, Poland.
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36
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Yang Z, Zhang Z, Chen D, Xu T, Wang Y, Sun L. Nanoparticle-Aided Nanoreactor for Nanoproteomics. Anal Chem 2021; 93:10568-10576. [PMID: 34297524 DOI: 10.1021/acs.analchem.1c01704] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Large-scale bottom-up proteomics of few even single cells is crucial for a better understanding of the roles played by cell-to-cell heterogeneity in disease and development. Novel proteomic methodologies with extremely high sensitivity are required for few even single-cell proteomics. Sample processing with high recovery and no contaminants is one key step. Here we developed a nanoparticle-aided nanoreactor for nanoproteomics (Nano3) technique for processing low-nanograms of mammalian cell proteins for proteome profiling. The Nano3 technique employed nanoparticles packed in a capillary channel to form a nanoreactor (≤30 nL) for concentrating, cleaning, and digesting proteins originally in a lysis buffer containing sodium dodecyl sulfate (SDS), followed by nanoRPLC-MS/MS analysis. The Nano3 method identified a 40-times higher number of proteins based on MS/MS from 2-ng mouse brain protein samples compared to the SP3 (single-pot solid-phase-enhanced sample preparation) method, which performed the sample processing using the nanoparticles in a 10 μL solution in an Eppendorf tube. The data indicates a drastically higher sample recovery of the Nano3 compared to the SP3 method for processing mass-limited proteome samples. In this pilot study, the Nano3 method was further applied in processing 10-1000 HeLa cells for bottom-up proteomics, producing 441 ± 263 (n = 4) (MS/MS) and 983 ± 292 (n = 4) [match between runs (MBR)+MS/MS] protein identifications from only 10 HeLa cells using a Q-Exactive HF mass spectrometer. The preliminary results render the Nano3 method a useful approach for processing few mammalian cells for proteome profiling.
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Affiliation(s)
- Zhichang Yang
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824 United States
| | - Zhaoran Zhang
- Department of Animal Sciences, Michigan State University, 766 Service Road, East Lansing, Michigan 48824 United States
| | - Daoyang Chen
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824 United States
| | - Tian Xu
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824 United States
| | - Yuan Wang
- Department of Animal Sciences, Michigan State University, 766 Service Road, East Lansing, Michigan 48824 United States
| | - Liangliang Sun
- Department of Chemistry, Michigan State University, 578 S Shaw Lane, East Lansing, Michigan 48824 United States
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37
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Akerman I, Maestro MA, De Franco E, Grau V, Flanagan S, García-Hurtado J, Mittler G, Ravassard P, Piemonti L, Ellard S, Hattersley AT, Ferrer J. Neonatal diabetes mutations disrupt a chromatin pioneering function that activates the human insulin gene. Cell Rep 2021; 35:108981. [PMID: 33852861 PMCID: PMC8052186 DOI: 10.1016/j.celrep.2021.108981] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 01/04/2021] [Accepted: 03/23/2021] [Indexed: 12/18/2022] Open
Abstract
Despite the central role of chromosomal context in gene transcription, human noncoding DNA variants are generally studied outside of their genomic location. This limits our understanding of disease-causing regulatory variants. INS promoter mutations cause recessive neonatal diabetes. We show that all INS promoter point mutations in 60 patients disrupt a CC dinucleotide, whereas none affect other elements important for episomal promoter function. To model CC mutations, we humanized an ∼3.1-kb region of the mouse Ins2 gene. This recapitulated developmental chromatin states and cell-specific transcription. A CC mutant allele, however, abrogated active chromatin formation during pancreas development. A search for transcription factors acting through this element revealed that another neonatal diabetes gene product, GLIS3, has a pioneer-like ability to derepress INS chromatin, which is hampered by the CC mutation. Our in vivo analysis, therefore, connects two human genetic defects in an essential mechanism for developmental activation of the INS gene.
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Affiliation(s)
- Ildem Akerman
- Institute of Metabolism and Systems Research (IMSR), Medical School, University of Birmingham, Birmingham, UK; Centre for Endocrinology, Diabetes and Metabolism (CEDAM), University of Birmingham, Birmingham, UK.
| | - Miguel Angel Maestro
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Elisa De Franco
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Vanessa Grau
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Sarah Flanagan
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Javier García-Hurtado
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain
| | - Gerhard Mittler
- Max-Planck Institute for Immunobiology and Epigenetics, Freiburg, Germany
| | - Philippe Ravassard
- INSERM, CNRS, Paris Brain Institute - Hôpital Pitié-Salpêtrière, Paris, France
| | - Lorenzo Piemonti
- Diabetes Research Institute, IRCCS Ospedale San Raffaele and Università Vita-Salute San Raffaele, Milan, Italy
| | - Sian Ellard
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK; Exeter Genomics Laboratory, Royal Devon and Exeter NHS Foundation Trust, Exeter, UK
| | - Andrew T Hattersley
- Institute of Biomedical and Clinical Science, University of Exeter Medical School, Exeter, UK
| | - Jorge Ferrer
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr. Aiguader 88, Barcelona 08003, Spain; Centro de Investigación Biomédica en red Diabetes y Enfermedades Metabólicas Asociadas (CIBERDEM), Barcelona, Spain; Section of Genetics and Genomics, Department of Metabolism, Digestion and Reproduction, Imperial College London, London, UK.
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38
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Rothenberg EV. Logic and lineage impacts on functional transcription factor deployment for T-cell fate commitment. Biophys J 2021; 120:4162-4181. [PMID: 33838137 PMCID: PMC8516641 DOI: 10.1016/j.bpj.2021.04.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Revised: 03/22/2021] [Accepted: 04/02/2021] [Indexed: 11/19/2022] Open
Abstract
Transcription factors are the major agents that read the regulatory sequence information in the genome to initiate changes in expression of specific genes, both in development and in physiological activation responses. Their actions depend on site-specific DNA binding and are largely guided by their individual DNA target sequence specificities. However, their action is far more conditional in a real developmental context than would be expected for simple reading of local genomic DNA sequence, which is common to all cells in the organism. They are constrained by slow-changing chromatin states and by interactions with other transcription factors, which affect their occupancy patterns of potential sites across the genome. These mechanisms lead to emergent discontinuities in function even for transcription factors with minimally changing expression. This is well revealed by diverse lineages of blood cells developing throughout life from hematopoietic stem cells, which use overlapping combinations of transcription factors to drive strongly divergent gene regulation programs. Here, using development of T lymphocytes from hematopoietic multipotent progenitor cells as a focus, recent evidence is reviewed on how binding specificity and dynamics, transcription factor cooperativity, and chromatin state changes impact the effective regulatory functions of key transcription factors including PU.1, Runx1, Notch-RBPJ, and Bcl11b.
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Affiliation(s)
- Ellen V Rothenberg
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California.
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39
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Bertero A. RNA Biogenesis Instructs Functional Inter-Chromosomal Genome Architecture. Front Genet 2021; 12:645863. [PMID: 33732290 PMCID: PMC7957078 DOI: 10.3389/fgene.2021.645863] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 02/08/2021] [Indexed: 12/12/2022] Open
Abstract
Three-dimensional (3D) genome organization has emerged as an important layer of gene regulation in development and disease. The functional properties of chromatin folding within individual chromosomes (i.e., intra-chromosomal or in cis) have been studied extensively. On the other hand, interactions across different chromosomes (i.e., inter-chromosomal or in trans) have received less attention, being often regarded as background noise or technical artifacts. This viewpoint has been challenged by emerging evidence of functional relationships between specific trans chromatin interactions and epigenetic control, transcription, and splicing. Therefore, it is an intriguing possibility that the key processes involved in the biogenesis of RNAs may both shape and be in turn influenced by inter-chromosomal genome architecture. Here I present the rationale behind this hypothesis, and discuss a potential experimental framework aimed at its formal testing. I present a specific example in the cardiac myocyte, a well-studied post-mitotic cell whose development and response to stress are associated with marked rearrangements of chromatin topology both in cis and in trans. I argue that RNA polymerase II clusters (i.e., transcription factories) and foci of the cardiac-specific splicing regulator RBM20 (i.e., splicing factories) exemplify the existence of trans-interacting chromatin domains (TIDs) with important roles in cellular homeostasis. Overall, I propose that inter-molecular 3D proximity between co-regulated nucleic acids may be a pervasive functional mechanism in biology.
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Affiliation(s)
- Alessandro Bertero
- Department of Laboratory Medicine and Pathology, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, WA, United States
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40
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Alizada A, Khyzha N, Wang L, Antounians L, Chen X, Khor M, Liang M, Rathnakumar K, Weirauch MT, Medina-Rivera A, Fish JE, Wilson MD. Conserved regulatory logic at accessible and inaccessible chromatin during the acute inflammatory response in mammals. Nat Commun 2021; 12:567. [PMID: 33495464 PMCID: PMC7835376 DOI: 10.1038/s41467-020-20765-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 12/18/2020] [Indexed: 12/18/2022] Open
Abstract
The regulatory elements controlling gene expression during acute inflammation are not fully elucidated. Here we report the identification of a set of NF-κB-bound elements and common chromatin landscapes underlying the acute inflammatory response across cell-types and mammalian species. Using primary vascular endothelial cells (human/mouse/bovine) treated with the pro-inflammatory cytokine, Tumor Necrosis Factor-α, we identify extensive (~30%) conserved orthologous binding of NF-κB to accessible, as well as nucleosome-occluded chromatin. Regions with the highest NF-κB occupancy pre-stimulation show dramatic increases in NF-κB binding and chromatin accessibility post-stimulation. These 'pre-bound' regions are typically conserved (~56%), contain multiple NF-κB motifs, are utilized by diverse cell types, and overlap rare non-coding mutations and common genetic variation associated with both inflammatory and cardiovascular phenotypes. Genetic ablation of conserved, 'pre-bound' NF-κB regions within the super-enhancer associated with the chemokine-encoding CCL2 gene and elsewhere supports the functional relevance of these elements.
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Affiliation(s)
- Azad Alizada
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Nadiya Khyzha
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
- University Health Network, Toronto General Hospital Research Institute, Toronto, Canada
| | - Liangxi Wang
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Lina Antounians
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Xiaoting Chen
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Melvin Khor
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
- University Health Network, Toronto General Hospital Research Institute, Toronto, Canada
| | - Minggao Liang
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- Department of Molecular Genetics, University of Toronto, Toronto, Canada
| | - Kumaragurubaran Rathnakumar
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- University Health Network, Toronto General Hospital Research Institute, Toronto, Canada
| | - Matthew T Weirauch
- Center for Autoimmune Genomics and Etiology, Cincinnati Children's Hospital, Cincinnati, OH, USA
- Division of Biomedical Informatics, Cincinnati Children's Hospital, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, OH, USA
| | - Alejandra Medina-Rivera
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada
- Laboratorio Internacional de Investigación sobre el Genoma Humano, Universidad Nacional Autónoma de México, Juriquilla, Mexico
| | - Jason E Fish
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada.
- University Health Network, Toronto General Hospital Research Institute, Toronto, Canada.
- University Health Network, Peter Munk Cardiac Centre, Toronto, Canada.
| | - Michael D Wilson
- Hospital for Sick Children, Genetics and Genome Biology, Toronto, Canada.
- Department of Molecular Genetics, University of Toronto, Toronto, Canada.
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41
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Abstract
Large amounts of effort have been invested in trying to understand how a single genome is able to specify the identity of hundreds of cell types. Inspired by some aspects of Caenorhabditis elegans biology, we implemented an in silico evolutionary strategy to produce gene regulatory networks (GRNs) that drive cell-specific gene expression patterns, mimicking the process of terminal cell differentiation. Dynamics of the gene regulatory networks are governed by a thermodynamic model of gene expression, which uses DNA sequences and transcription factor degenerate position weight matrixes as input. In a version of the model, we included chromatin accessibility. Experimentally, it has been determined that cell-specific and broadly expressed genes are regulated differently. In our in silico evolved GRNs, broadly expressed genes are regulated very redundantly and the architecture of their cis-regulatory modules is different, in accordance to what has been found in C. elegans and also in other systems. Finally, we found differences in topological positions in GRNs between these two classes of genes, which help to explain why broadly expressed genes are so resilient to mutations. Overall, our results offer an explanatory hypothesis on why broadly expressed genes are regulated so redundantly compared to cell-specific genes, which can be extrapolated to phenomena such as ChIP-seq HOT regions.
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Affiliation(s)
- Carlos Mora-Martinez
- Evo-devo Helsinki community, Centre of Excellence in Experimental and Computational Developmental Biology, Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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42
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Li J, Lee YK, Fu W, Whalen AM, Estable MC, Raftery LA, White K, Weiner L, Brissette JL. Modeling by disruption and a selected-for partner for the nude locus. EMBO Rep 2020; 22:e49804. [PMID: 33369874 PMCID: PMC7926259 DOI: 10.15252/embr.201949804] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 11/03/2020] [Accepted: 11/20/2020] [Indexed: 12/25/2022] Open
Abstract
A long‐standing problem in biology is how to dissect traits for which no tractable model exists. Here, we screen for genes like the nude locus (Foxn1)—genes central to mammalian hair and thymus development—using animals that never evolved hair, thymi, or Foxn1. Fruit flies are morphologically disrupted by the FOXN1 transcription factor and rescued by weak reductions in fly gene function, revealing molecules that potently synergize with FOXN1 to effect dramatic, chaotic change. Strong synergy/effectivity in flies is expected to reflect strong selection/functionality (purpose) in mammals; the more disruptive a molecular interaction is in alien contexts (flies), the more beneficial it will be in its natural, formative contexts (mammals). The approach identifies Aff4 as the first nude‐like locus, as murine AFF4 and FOXN1 cooperatively induce similar cutaneous/thymic phenotypes, similar gene expression programs, and the same step of transcription, pre‐initiation complex formation. These AFF4 functions are unexpected, as AFF4 also serves as a scaffold in common transcriptional‐elongation complexes. Most likely, the approach works because an interaction's power to disrupt is the inevitable consequence of its selected‐for power to benefit.
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Affiliation(s)
- Jian Li
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.,Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Yun-Kyoung Lee
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA
| | - Wenyu Fu
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.,Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Anne M Whalen
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Mario C Estable
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Laurel A Raftery
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Kristin White
- Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Lorin Weiner
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.,Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
| | - Janice L Brissette
- Department of Cell Biology, State University of New York Downstate Health Sciences University, Brooklyn, NY, USA.,Cutaneous Biology Research Center, Massachusetts General Hospital and Harvard Medical School, Charlestown, MA, USA
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43
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Abstract
Simple biophysical models successfully describe bacterial regulatory code, by predicting gene expression from DNA sequences that bind specialized regulatory proteins. Analogous simple models fail in multicellular organisms, where regulatory proteins bind DNA very transiently, yet, nevertheless, effect precise control over gene expression. To date, the more general, “nonequilibrium” models have proven difficult to analyze and connect to data. Here, we reduce this complexity theoretically, by constructing simple nonequilibrium models which perform optimal gene regulation within known experimental constraints. In prokaryotes, thermodynamic models of gene regulation provide a highly quantitative mapping from promoter sequences to gene-expression levels that is compatible with in vivo and in vitro biophysical measurements. Such concordance has not been achieved for models of enhancer function in eukaryotes. In equilibrium models, it is difficult to reconcile the reported short transcription factor (TF) residence times on the DNA with the high specificity of regulation. In nonequilibrium models, progress is difficult due to an explosion in the number of parameters. Here, we navigate this complexity by looking for minimal nonequilibrium enhancer models that yield desired regulatory phenotypes: low TF residence time, high specificity, and tunable cooperativity. We find that a single extra parameter, interpretable as the “linking rate,” by which bound TFs interact with Mediator components, enables our models to escape equilibrium bounds and access optimal regulatory phenotypes, while remaining consistent with the reported phenomenology and simple enough to be inferred from upcoming experiments. We further find that high specificity in nonequilibrium models is in a trade-off with gene-expression noise, predicting bursty dynamics—an experimentally observed hallmark of eukaryotic transcription. By drastically reducing the vast parameter space of nonequilibrium enhancer models to a much smaller subspace that optimally realizes biological function, we deliver a rich class of models that could be tractably inferred from data in the near future.
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44
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Bridoux L, Zarrineh P, Mallen J, Phuycharoen M, Latorre V, Ladam F, Losa M, Baker SM, Sagerstrom C, Mace KA, Rattray M, Bobola N. HOX paralogs selectively convert binding of ubiquitous transcription factors into tissue-specific patterns of enhancer activation. PLoS Genet 2020; 16:e1009162. [PMID: 33315856 PMCID: PMC7769617 DOI: 10.1371/journal.pgen.1009162] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Revised: 12/28/2020] [Accepted: 09/28/2020] [Indexed: 11/18/2022] Open
Abstract
Gene expression programs determine cell fate in embryonic development and their dysregulation results in disease. Transcription factors (TFs) control gene expression by binding to enhancers, but how TFs select and activate their target enhancers is still unclear. HOX TFs share conserved homeodomains with highly similar sequence recognition properties, yet they impart the identity of different animal body parts. To understand how HOX TFs control their specific transcriptional programs in vivo, we compared HOXA2 and HOXA3 binding profiles in the mouse embryo. HOXA2 and HOXA3 directly cooperate with TALE TFs and selectively target different subsets of a broad TALE chromatin platform. Binding of HOX and tissue-specific TFs convert low affinity TALE binding into high confidence, tissue-specific binding events, which bear the mark of active enhancers. We propose that HOX paralogs, alone and in combination with tissue-specific TFs, generate tissue-specific transcriptional outputs by modulating the activity of TALE TFs at selected enhancers.
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Affiliation(s)
- Laure Bridoux
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Peyman Zarrineh
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
| | - Joshua Mallen
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Mike Phuycharoen
- Department of Computer Science, University of Manchester, Manchester, United Kingdom
| | - Victor Latorre
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Frank Ladam
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusets, United States of America
| | - Marta Losa
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
| | - Syed Murtuza Baker
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
- School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Charles Sagerstrom
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusets, United States of America
| | - Kimberly A. Mace
- School of Biological Sciences, University of Manchester, Manchester, United Kingdom
| | - Magnus Rattray
- School of Health Sciences, University of Manchester, Manchester, United Kingdom
| | - Nicoletta Bobola
- School of Medical Sciences, University of Manchester, Manchester, United Kingdom
- * E-mail:
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45
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Azpeitia E, Balanzario EP, Wagner A. Signaling pathways have an inherent need for noise to acquire information. BMC Bioinformatics 2020; 21:462. [PMID: 33066727 PMCID: PMC7568421 DOI: 10.1186/s12859-020-03778-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 09/23/2020] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND All living systems acquire information about their environment. At the cellular level, they do so through signaling pathways. Such pathways rely on reversible binding interactions between molecules that detect and transmit the presence of an extracellular cue or signal to the cell's interior. These interactions are inherently stochastic and thus noisy. On the one hand, noise can cause a signaling pathway to produce the same response for different stimuli, which reduces the amount of information a pathway acquires. On the other hand, in processes such as stochastic resonance, noise can improve the detection of weak stimuli and thus the acquisition of information. It is not clear whether the kinetic parameters that determine a pathway's operation cause noise to reduce or increase the acquisition of information. RESULTS We analyze how the kinetic properties of the reversible binding interactions used by signaling pathways affect the relationship between noise, the response to a signal, and information acquisition. Our results show that, under a wide range of biologically sensible parameter values, a noisy dynamic of reversible binding interactions is necessary to produce distinct responses to different stimuli. As a consequence, noise is indispensable for the acquisition of information in signaling pathways. CONCLUSIONS Our observations go beyond previous work by showing that noise plays a positive role in signaling pathways, demonstrating that noise is essential when such pathways acquire information.
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Affiliation(s)
- Eugenio Azpeitia
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zurich, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
- Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México, Morelia, Mexico
| | - Eugenio P Balanzario
- Centro de Ciencias Matemáticas, Universidad Nacional Autónoma de México, Morelia, Mexico
| | - Andreas Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, Zurich, Switzerland.
- Swiss Institute of Bioinformatics, Lausanne, Switzerland.
- The Santa Fe Institute, Santa Fe, NM, USA.
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46
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Zeitlinger J. Seven myths of how transcription factors read the cis-regulatory code. CURRENT OPINION IN SYSTEMS BIOLOGY 2020; 23:22-31. [PMID: 33134611 PMCID: PMC7592701 DOI: 10.1016/j.coisb.2020.08.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Genomics data are now being generated at large quantities, of exquisite high resolution and from single cells. They offer a unique opportunity to develop powerful machine learning algorithms, including neural networks, to uncover the rules of the cis-regulatory code. However, current modeling assumptions are often not based on state-of-the-art knowledge of the cis-regulatory code from transcription, developmental genetics, imaging and structural studies. Here I aim to fill this gap by giving a brief historical overview of the field, describing common misconceptions and providing knowledge that might help to guide computational approaches. I will describe the principles and mechanisms involved in the combinatorial requirement of transcription factor binding motifs for enhancer activity, including the role of chromatin accessibility, repressors and low-affinity motifs in the cis-regulatory code. Deciphering the cis-regulatory code would unlock an enormous amount of regulatory information in the genome and would allow us to locate cis-regulatory genetic variants involved in development and disease.
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Affiliation(s)
- Julia Zeitlinger
- Stowers Institute for Medical Research, Kansas City, MO, USA
- The University of Kansas Medical Center, Kansas City, KS, USA
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47
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Overton IM, Sims AH, Owen JA, Heale BSE, Ford MJ, Lubbock ALR, Pairo-Castineira E, Essafi A. Functional Transcription Factor Target Networks Illuminate Control of Epithelial Remodelling. Cancers (Basel) 2020; 12:cancers12102823. [PMID: 33007944 PMCID: PMC7652213 DOI: 10.3390/cancers12102823] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Revised: 09/16/2020] [Accepted: 09/24/2020] [Indexed: 12/15/2022] Open
Abstract
Cell identity is governed by gene expression, regulated by transcription factor (TF) binding at cis-regulatory modules. Decoding the relationship between TF binding patterns and gene regulation is nontrivial, remaining a fundamental limitation in understanding cell decision-making. We developed the NetNC software to predict functionally active regulation of TF targets; demonstrated on nine datasets for the TFs Snail, Twist, and modENCODE Highly Occupied Target (HOT) regions. Snail and Twist are canonical drivers of epithelial to mesenchymal transition (EMT), a cell programme important in development, tumour progression and fibrosis. Predicted "neutral" (non-functional) TF binding always accounted for the majority (50% to 95%) of candidate target genes from statistically significant peaks and HOT regions had higher functional binding than most of the Snail and Twist datasets examined. Our results illuminated conserved gene networks that control epithelial plasticity in development and disease. We identified new gene functions and network modules including crosstalk with notch signalling and regulation of chromatin organisation, evidencing networks that reshape Waddington's epigenetic landscape during epithelial remodelling. Expression of orthologous functional TF targets discriminated breast cancer molecular subtypes and predicted novel tumour biology, with implications for precision medicine. Predicted invasion roles were validated using a tractable cell model, supporting our approach.
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Affiliation(s)
- Ian M. Overton
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
- Department of Systems Biology, Harvard University, Boston, MA 02115, USA;
- Centre for Synthetic and Systems Biology (SynthSys), University of Edinburgh, Edinburgh EH9 3BF, UK
- Patrick G Johnston Centre for Cancer Research, Queen’s University Belfast, Belfast BT9 7AE, UK
- Correspondence:
| | - Andrew H. Sims
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Jeremy A. Owen
- Department of Systems Biology, Harvard University, Boston, MA 02115, USA;
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Bret S. E. Heale
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Matthew J. Ford
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Alexander L. R. Lubbock
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Erola Pairo-Castineira
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
| | - Abdelkader Essafi
- MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK; (A.H.S.); (B.S.E.H.); (M.J.F.); (A.L.R.L.); (E.P.-C.); (A.E.)
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48
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Kopacz A, Kloska D, Forman HJ, Jozkowicz A, Grochot-Przeczek A. Beyond repression of Nrf2: An update on Keap1. Free Radic Biol Med 2020; 157:63-74. [PMID: 32234331 PMCID: PMC7732858 DOI: 10.1016/j.freeradbiomed.2020.03.023] [Citation(s) in RCA: 144] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Revised: 03/04/2020] [Accepted: 03/24/2020] [Indexed: 12/14/2022]
Abstract
Nrf2 (NFE2L2 - nuclear factor (erythroid-derived 2)-like 2) is a transcription factor, which is repressed by interaction with a redox-sensitive protein Keap1 (Kelch-like ECH-associated protein 1). Deregulation of Nrf2 transcriptional activity has been described in the pathogenesis of multiple diseases, and the Nrf2/Keap1 axis has emerged as a crucial modulator of cellular homeostasis. Whereas the significance of Nrf2 in the modulation of biological processes has been well established and broadly discussed in detail, the focus on Keap1 rarely goes beyond the regulation of Nrf2 activity and redox sensing. However, recent studies and scrutinized analysis of available data point to Keap1 as an intriguing and potent regulator of cellular function. This review aims to shed more light on Keap1 structure, interactome, regulation and non-canonical functions, thereby enhancing its significance in cell biology. We also intend to highlight the impact of balance between Keap1 and Nrf2 in the maintenance of cellular homeostasis.
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Affiliation(s)
- Aleksandra Kopacz
- Department of Medical Biotechnology, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
| | - Damian Kloska
- Department of Medical Biotechnology, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
| | - Henry Jay Forman
- Andrus Gerontology Center of the Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA, 90089-0191, USA
| | - Alicja Jozkowicz
- Department of Medical Biotechnology, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland
| | - Anna Grochot-Przeczek
- Department of Medical Biotechnology, Faculty of Biochemistry Biophysics and Biotechnology, Jagiellonian University, 30-387, Krakow, Poland.
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49
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Sandra US, Shukla A, Kolthur-Seetharam U. Search and Capture: Disorder Rules Gene Promoter Selection. Trends Genet 2020; 36:721-722. [PMID: 32739029 DOI: 10.1016/j.tig.2020.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 07/09/2020] [Indexed: 10/23/2022]
Abstract
Intrinsically disordered regions (IDRs) are preponderant in transcription factors (TFs) and are evolutionarily less conserved vis-à-vis DNA-binding domains (DBDs). Unexpected findings from Barkai and colleagues, which demonstrate that promoter selectivity is determined by IDRs, should significantly enhance our understanding of gene expression regulation.
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Affiliation(s)
- U S Sandra
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, Maharashtra, India
| | - Arushi Shukla
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, Maharashtra, India
| | - Ullas Kolthur-Seetharam
- Department of Biological Sciences, Tata Institute of Fundamental Research, Homi Bhabha Road, Colaba, Mumbai 400 005, Maharashtra, India.
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50
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Long-term association of a transcription factor with its chromatin binding site can stabilize gene expression and cell fate commitment. Proc Natl Acad Sci U S A 2020; 117:15075-15084. [PMID: 32532919 PMCID: PMC7334453 DOI: 10.1073/pnas.2000467117] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Some kinds of transcription factor proteins are very important in initiating and guiding cell fate differentiation. Overexpression of these factors can force many other kinds of cells to become muscle or nerve. Examples are MyoD for muscle and Ascl1 for nerve. It is not known how long such a factor must remain bound to its binding site for it to have its function; this could be seconds, minutes, hours, or days. We have developed a procedure to determine the required residence time for the Ascl1 nerve factor to have its function. This factor remains closely associated with its chromatin binding site for hours or days. This may be a general characteristic of such factors in nondividing (adult) cells. Some lineage-determining transcription factors are overwhelmingly important in directing embryonic cells to a particular differentiation pathway, such as Ascl1 for nerve. They also have an exceptionally strong ability to force cells to change from an unrelated pathway to one preferred by their action. Transcription factors are believed to have a very short residence time of only a few seconds on their specific DNA or chromatin-binding sites. We have developed a procedure in which DNA containing one copy of the binding site for the neural-inducing factor Ascl1 is injected directly into a Xenopus oocyte nucleus which has been preloaded with a limiting amount of the Ascl1 transcription factor protein. This is followed by a further injection of DNA as a competitor, either in a plasmid or in chromosomal DNA, containing the same binding site but with a different reporter. Importantly, expression of the reporter provides a measure of the function of the transcription factor in addition to its residence time. The same long residence time and resistance to competition are seen with the estrogen receptor and its DNA response elements. We find that in this nondividing oocyte, the nerve-inducing factor Ascl1 can remain bound to a specific chromatin site for hours or days and thereby help to stabilize gene expression. This stability of transcription factor binding to chromatin is a necessary part of its action because removal of this factor causes discontinuation of its effect on gene expression. Stable transcription factor binding may be a characteristic of nondividing cells.
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