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Lountos GT, Cherry S, Tropea JE, Wlodawer A, Miller M. Structural basis for cell type specific DNA binding of C/EBPβ: The case of cell cycle inhibitor p15INK4b promoter. J Struct Biol 2022; 214:107918. [PMID: 36343842 PMCID: PMC9909937 DOI: 10.1016/j.jsb.2022.107918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/22/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
C/EBPβ is a key regulator of numerous cellular processes, but it can also contribute to tumorigenesis and viral diseases. It binds to specific DNA sequences (C/EBP sites) and interacts with other transcription factors to control expression of multiple eukaryotic genes in a tissue and cell-type dependent manner. A body of evidence has established that cell-type-specific regulatory information is contained in the local DNA sequence of the binding motif. In human epithelial cells, C/EBPβ is an essential cofactor for TGFβ signaling in the case of Smad2/3/4 and FoxO-dependent induction of the cell cycle inhibitor, p15INK4b. In the TGFβ-responsive region 2 of the p15INK4b promoter, the Smad binding site is flanked by a C/EBP site, CTTAA•GAAAG, which differs from the canonical, palindromic ATTGC•GCAAT motif. The X-ray crystal structure of C/EBPβ bound to the p15INK4b promoter fragment shows how GCGC-to-AAGA substitution generates changes in the intermolecular interactions in the protein-DNA interface that enhances C/EBPβ binding specificity, limits possible epigenetic regulation of the promoter, and generates a DNA element with a unique pattern of methyl groups in the major groove. Significantly, CT/GA dinucleotides located at the 5'ends of the double stranded element maintain local narrowing of the DNA minor groove width that is necessary for DNA recognition. Our results suggest that C/EBPβ would accept all forms of modified cytosine in the context of the CpT site. This contrasts with the effect on the consensus motif, where C/EBPβ binding is modestly increased by cytosine methylation, but substantially decreased by hydroxymethylation.
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Affiliation(s)
- George T Lountos
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.
| | - Scott Cherry
- Protein Purification Core, Center for Structural Biology, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Joseph E Tropea
- Protein Purification Core, Center for Structural Biology, National Cancer Institute, Frederick, MD 21702-1201, USA
| | - Alexander Wlodawer
- Protein Structure Section, Center for Structural Biology, National Cancer Institute, Frederick, MD 21702-1201 USA
| | - Maria Miller
- Protein Structure Section, Center for Structural Biology, National Cancer Institute, Frederick, MD 21702-1201 USA
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2
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Varticovski L, Stavreva DA, McGowan A, Raziuddin R, Hager GL. Endocrine disruptors of sex hormone activities. Mol Cell Endocrinol 2022; 539:111415. [PMID: 34339825 PMCID: PMC8762672 DOI: 10.1016/j.mce.2021.111415] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 12/20/2022]
Abstract
Sex hormones, such as androgens, estrogens and progestins are naturally occurring compounds that tightly regulate endocrine systems in a variety of living organisms. Uncontrolled environmental exposure to these hormones or their biological and synthetic mimetics has been widely documented. Furthermore, water contaminants penetrate soil to affect flora, fauna and ultimately humans. Because endocrine systems evolved to respond to very small changes in hormone levels, the low levels found in the environment cannot be ignored. The combined actions of sex hormones with glucocorticoids and other nuclear receptors disruptors creates additional level of complexity including the newly described "dynamic assisted loading" mechanism. We reviewed the extensive literature pertaining to world-wide detection of these disruptors and created a detailed Table on the development and current status of methods used for their analysis.
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Affiliation(s)
- L Varticovski
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
| | - D A Stavreva
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - A McGowan
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - R Raziuddin
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA
| | - G L Hager
- Laboratory of Receptor Biology and Gene Expression, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD, 20892, USA.
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3
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Xu Z, Asakawa S. A model explaining mRNA level fluctuations based on activity demands and RNA age. PLoS Comput Biol 2021; 17:e1009188. [PMID: 34297727 PMCID: PMC8336849 DOI: 10.1371/journal.pcbi.1009188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 08/04/2021] [Accepted: 06/17/2021] [Indexed: 11/19/2022] Open
Abstract
Cellular RNA levels typically fluctuate and are influenced by different transcription rates and RNA degradation rates. However, the understanding of the fundamental relationships between RNA abundance, environmental stimuli, RNA activities, and RNA age distributions is incomplete. Furthermore, the rates of RNA degradation and transcription are difficult to measure in transcriptomic experiments in living organisms, especially in studies involving humans. A model based on activity demands and RNA age was developed to explore the mechanisms of RNA level fluctuations. Using single-cell time-series gene expression experimental data, we assessed the transcription rates, RNA degradation rates, RNA life spans, RNA demand, accumulated transcription levels, and accumulated RNA degradation levels. This model could also predict RNA levels under simulation backgrounds, such as stimuli that induce regular oscillations in RNA abundance, stable RNA levels over time that result from long-term shortage of total RNA activity or from uncontrollable transcription, and relationships between RNA/protein levels and metabolic rates. This information contributes to existing knowledge. Detected cellular RNA levels usually fluctuate. The understanding of the fundamental relationships between RNA level fluctuations, the rates of RNA degradation and transcription, environmental stimuli, RNA activities, and RNA age distributions is incomplete. In the present research, we developed a model based on the demands of RNA (related to intrinsic and/or extrinsic information), RNA age (determines the survival time and biological activity of an RNA), transcription, and RNA degradation to explain the mechanism underlying intracellular RNA level fluctuations. We also explored applicability of the model for analysing dynamic processes between interacting biomolecules, such as the relationship between RNA and protein level fluctuations. Using single-cell time-series gene expression experimental data, we assessed some biological parameters, such as transcription rates, RNA degradation rates, and RNA life spans. This model could also predict RNA levels under simulation backgrounds, such as stimuli that induce regular oscillations in RNA abundance, stable RNA levels over time that result from long-term shortage of total RNA activity or from uncontrollable transcription, and relationships between RNA/protein levels and metabolic rates. This information contributes to existing knowledge and provides a new perspective for future studies.
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Affiliation(s)
- Zhongneng Xu
- Department of Ecology, Jinan University, Guangzhou, China
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
- * E-mail: ,
| | - Shuichi Asakawa
- Department of Aquatic Bioscience, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Tokyo, Japan
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4
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Qiu H, Zhang B, Zhou T. Explicit effect of stochastic reaction delay on gene expression. Phys Rev E 2020; 101:012405. [PMID: 32069597 DOI: 10.1103/physreve.101.012405] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Indexed: 11/07/2022]
Abstract
Apart from intrinsic stochastic variability, gene expression also involves stochastic reaction delay arising from heterogeneity and fluctuation processes, which can affect the efficiency of reactants (e.g., mRNA or protein) in exploring their environments. In contrast to the former that has been extensively investigated, the impact of the latter on gene expression remains not fully understood. Here, we analyze a non-Markovian model of bursty gene expression with general delay distribution. We analytically find that the effect of stochastic reaction delay is equivalent to the introduction of negative feedback, and stationary protein distribution only depends on the mean of the delay and is independent of its distribution. We numerically show that the stochastic reaction delay always slightly amplifies the mean protein level but remarkably reduces the protein noise (quantified by the ratio of the variance over the squared average). Our analysis indicates that stochastic reaction delay is an important factor affecting gene expression.
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Affiliation(s)
- Huahai Qiu
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China
| | - Bengong Zhang
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China
| | - Tianshou Zhou
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China.,Key Laboratory of Computational Mathematics, School of Mathematics, Sun Yat-sen University, Guangdong Province, Guangzhou 510275, People's Republic of China
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5
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Wu J, Gupta M, Hussein AI, Gerstenfeld L. Bayesian modeling of factorial time-course data with applications to a bone aging gene expression study. J Appl Stat 2020; 48:1730-1754. [PMID: 34295011 DOI: 10.1080/02664763.2020.1772733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Many scientific studies, especially in the biomedical sciences, generate data measured simultaneously over a multitude of units, over a period of time, and under different conditions or combinations of factors. Often, an important question of interest asked relates to which units behave similarly under different conditions, but measuring the variation over time complicates the analysis significantly. In this article we address such a problem arising from a gene expression study relating to bone aging, and develop a Bayesian statistical method that can simultaneously detect and uncover signals on three levels within such data: factorial, longitudinal, and transcriptional. Our model framework considers both cluster and time-point-specific parameters and these parameters uniquely determine the shapes of the temporal gene expression profiles, allowing the discovery and characterization of latent gene clusters based on similar underlying biological mechanisms. Our methodology was successfully applied to discover transcriptional networks in a microarray data set comparing the transcriptomic changes that occurred during bone aging in male and female mice expressing one or both copies of the bromodomain (Brd2) gene, a transcriptional regulator which exhibits an age-dependent sex-linked bone loss phenotype.
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Affiliation(s)
- Joseph Wu
- Boston University School of Public Health, Boston, MA, U. S. A.,Pfizer, Inc., Groton, CT, U.S.A
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6
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Markovian approaches to modeling intracellular reaction processes with molecular memory. Proc Natl Acad Sci U S A 2019; 116:23542-23550. [PMID: 31685609 PMCID: PMC6876203 DOI: 10.1073/pnas.1913926116] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Many cellular processes are governed by stochastic reaction events. These events do not necessarily occur in single steps of individual molecules, and, conversely, each birth or death of a macromolecule (e.g., protein) could involve several small reaction steps, creating a memory between individual events and thus leading to nonmarkovian reaction kinetics. Characterizing this kinetics is challenging. Here, we develop a systematic approach for a general reaction network with arbitrary intrinsic waiting-time distributions, which includes the stationary generalized chemical-master equation (sgCME), the stationary generalized Fokker-Planck equation, and the generalized linear-noise approximation. The first formulation converts a nonmarkovian issue into a markovian one by introducing effective transition rates (that explicitly decode the effect of molecular memory) for the reactions in an equivalent reaction network with the same substrates but without molecular memory. Nonmarkovian features of the reaction kinetics can be revealed by solving the sgCME. The latter 2 formulations can be used in the fast evaluation of fluctuations. These formulations can have broad applications, and, in particular, they may help us discover new biological knowledge underlying memory effects. When they are applied to generalized stochastic models of gene-expression regulation, we find that molecular memory is in effect equivalent to a feedback and can induce bimodality, fine-tune the expression noise, and induce switch.
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7
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Stavreva DA, Garcia DA, Fettweis G, Gudla PR, Zaki GF, Soni V, McGowan A, Williams G, Huynh A, Palangat M, Schiltz RL, Johnson TA, Presman DM, Ferguson ML, Pegoraro G, Upadhyaya A, Hager GL. Transcriptional Bursting and Co-bursting Regulation by Steroid Hormone Release Pattern and Transcription Factor Mobility. Mol Cell 2019; 75:1161-1177.e11. [PMID: 31421980 PMCID: PMC6754282 DOI: 10.1016/j.molcel.2019.06.042] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 02/07/2019] [Accepted: 06/26/2019] [Indexed: 10/26/2022]
Abstract
Genes are transcribed in a discontinuous pattern referred to as RNA bursting, but the mechanisms regulating this process are unclear. Although many physiological signals, including glucocorticoid hormones, are pulsatile, the effects of transient stimulation on bursting are unknown. Here we characterize RNA synthesis from single-copy glucocorticoid receptor (GR)-regulated transcription sites (TSs) under pulsed (ultradian) and constant hormone stimulation. In contrast to constant stimulation, pulsed stimulation induces restricted bursting centered around the hormonal pulse. Moreover, we demonstrate that transcription factor (TF) nuclear mobility determines burst duration, whereas its bound fraction determines burst frequency. Using 3D tracking of TSs, we directly correlate TF binding and RNA synthesis at a specific promoter. Finally, we uncover a striking co-bursting pattern between TSs located at proximal and distal positions in the nucleus. Together, our data reveal a dynamic interplay between TF mobility and RNA bursting that is responsive to stimuli strength, type, modality, and duration.
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Affiliation(s)
- Diana A Stavreva
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA.
| | - David A Garcia
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA; Department of Physics and Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Gregory Fettweis
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Prabhakar R Gudla
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - George F Zaki
- High Performance Computing Group, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Vikas Soni
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Andrew McGowan
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Geneva Williams
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Anh Huynh
- Department of Physics and Graduate Program in Biomolecular Science, Boise State University, Boise, ID 83725, USA
| | - Murali Palangat
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - R Louis Schiltz
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Thomas A Johnson
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Diego M Presman
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Matthew L Ferguson
- Department of Physics and Graduate Program in Biomolecular Science, Boise State University, Boise, ID 83725, USA
| | - Gianluca Pegoraro
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA
| | - Arpita Upadhyaya
- Department of Physics and Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, 41 Library Drive, Center for Cancer Research, NCI, NIH, Bethesda, MD 20892-5055, USA.
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8
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Qiu H, Zhang B, Zhou T. Analytical results for a generalized model of bursty gene expression with molecular memory. Phys Rev E 2019; 100:012128. [PMID: 31499786 DOI: 10.1103/physreve.100.012128] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Indexed: 06/10/2023]
Abstract
The activation of a gene is a complex biochemical process and could involve small steps, creating a memory between individual events. However, the effect of this molecular memory was often neglected in previous work. How the molecular memory affects gene expression remains not fully explored. We analyze a stochastic model of bursty gene expression, where the waiting time from inactivation to activation is assumed to follow a nonexponential (in fact, Erlang) distribution. We derive the analytical expression for the gene-product distribution, which explicitly traces the effect of molecule memory. Interestingly, we find that the effect of molecular memory is equivalent to the introduction of feedback. In addition, we analytically show that the stationary distribution is always super-Poissonian, independent of the detail of the waiting-time distribution, and there is the optimal step size that minimizes the Fano factor for any given mean burst size and is a decreasing function of the mean burst size. These analytical results indicate that molecular memory is an unneglectable factor affecting gene expression.
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Affiliation(s)
- Huahai Qiu
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China
| | - Bengong Zhang
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China
| | - Tianshou Zhou
- School of Mathematics and Computers, Wuhan Textile University, Wuhan 430200, People's Republic of China
- Key Laboratory of Computational Mathematics, Guangdong Province, and School of Mathematics, Sun Yat-sen University, Guangzhou 510275, People's Republic of China
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9
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Hou L, Li B, Ding D, Kang L, Wang X. CREB-B acts as a key mediator of NPF/NO pathway involved in phase-related locomotor plasticity in locusts. PLoS Genet 2019; 15:e1008176. [PMID: 31150381 PMCID: PMC6561586 DOI: 10.1371/journal.pgen.1008176] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 06/12/2019] [Accepted: 05/07/2019] [Indexed: 12/14/2022] Open
Abstract
Gene expression changes in neural systems are essential for environment-induced behavioral plasticity in animals; however, neuronal signaling pathways mediating the effect of external stimuli on transcriptional changes are largely unknown. Recently, we have demonstrated that the neuropeptide F (NPF)/nitric oxide (NO) signaling pathway plays a regulatory role in phase-related locomotor plasticity in the migratory locust, Locusta migratoria. Here, we report that a conserved transcription factor, cAMP response element-binding protein B (CREB-B), is a key mediator involved in the signaling pathway from NPF2 to NOS in the migratory locust, triggering locomotor activity shift between solitarious and gregarious phases. We find that CREB-B directly activates brain NOS expression by interacting with NOS promoter region. The phosphorylation at serine 110 site of CREB-B dynamically changes in response to population density variation and is negatively controlled by NPF2. The involvement of CREB-B in NPF2-regulated locomotor plasticity is further validated by RNAi experiment and behavioral assay. Furthermore, we reveal that protein kinase A mediates the regulatory effects of NPF2 on CREB-B phosphorylation and NOS transcription. These findings highlight a precise signal cascade underlying environment-induced behavioral plasticity.
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Affiliation(s)
- Li Hou
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Beibei Li
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Ding Ding
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Le Kang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China
| | - Xianhui Wang
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
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10
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Monczor F, Chatzopoulou A, Zappia CD, Houtman R, Meijer OC, Fitzsimons CP. A Model of Glucocorticoid Receptor Interaction With Coregulators Predicts Transcriptional Regulation of Target Genes. Front Pharmacol 2019; 10:214. [PMID: 30930776 PMCID: PMC6425864 DOI: 10.3389/fphar.2019.00214] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/20/2019] [Indexed: 12/14/2022] Open
Abstract
Regulatory factors that control gene transcription in multicellular organisms are assembled in multicomponent complexes by combinatorial interactions. In this context, nuclear receptors provide well-characterized and physiologically relevant systems to study ligand-induced transcription resulting from the integration of cellular and genomic information in a cell- and gene-specific manner. Here, we developed a mathematical model describing the interactions between the glucocorticoid receptor (GR) and other components of a multifactorial regulatory complex controlling the transcription of GR-target genes, such as coregulator peptides. We support the validity of the model in relation to gene-specific GR transactivation with gene transcription data from A549 cells and in vitro real time quantification of coregulator-GR interactions. The model accurately describes and helps to interpret ligand-specific and gene-specific transcriptional regulation by the GR. The comprehensive character of the model allows future insight into the function and relative contribution of the molecular species proposed in ligand- and gene-specific transcriptional regulation.
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Affiliation(s)
- Federico Monczor
- Laboratorio de Farmacología de Receptores, Instituto de Investigaciones Farmacológicas, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Antonia Chatzopoulou
- Leiden Academic Center for Drug Research, Leiden University, Leiden, Netherlands
| | - Carlos Daniel Zappia
- Laboratorio de Farmacología de Receptores, Instituto de Investigaciones Farmacológicas, Universidad de Buenos Aires-Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - René Houtman
- PamGene International B.V., 's-Hertogenbosch, Netherlands
| | - Onno C Meijer
- Division of Endocrinology, Department of Internal Medicine, Leiden University Medical Centre, Leiden, Netherlands
| | - Carlos P Fitzsimons
- Neuroscience Collaboration, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
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11
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Montenegro YHA, de Queiroga Nascimento D, de Assis TO, Santos-Lopes SSD. The epigenetics of the hypothalamic-pituitary-adrenal axis in fetal development. Ann Hum Genet 2019; 83:195-213. [PMID: 30843189 DOI: 10.1111/ahg.12306] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Revised: 02/13/2019] [Accepted: 02/14/2019] [Indexed: 01/16/2023]
Abstract
The hypothalamic-pituitary-adrenal (HPA) axis is an important hormonal mechanism of the human body and is extremely programmable during embryonic and fetal development. Analyzing its development in this period is the key to understanding in fact how vulnerabilities of congenital diseases occur and any other changes in the phenotypic and histophysiological aspects of the fetus. The environment in which the mother is exposed during the gestational period can influence this axis. Knowing this, our objective was to analyze in recent research the possible impact of epigenetic programming on the HPA axis and its consequences for fetal development. This review brought together articles from two databases: ScienceDirect and PUBMED researched based on key words such as "epigenetics, HPA axis, cardiovascular disease, and circulatory problems" where it demonstrated full relevance in experimental and scientific settings. A total of 101 articles were selected following the criteria established by the researchers. Thus, it was possible to verify that the development of the HPA axis is directly related to changes that occur in the cardiovascular system, to the cerebral growth and other systems depending on the influence that it receives in the period of fetal formation.
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12
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Mazina MY, Kovalenko EV, Derevyanko PK, Nikolenko JV, Krasnov AN, Vorobyeva NE. One signal stimulates different transcriptional activation mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2018; 1861:178-189. [PMID: 29410380 DOI: 10.1016/j.bbagrm.2018.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Revised: 12/10/2017] [Accepted: 01/15/2018] [Indexed: 12/30/2022]
Abstract
Transcriptional activation is often represented as a "one-step process" that involves the simultaneous recruitment of co-activator proteins, leading to a change in gene status. Using Drosophila developmental ecdysone-dependent genes as a model, we demonstrated that activation of transcription is instead a continuous process that consists of a number of steps at which different phases of transcription (initiation or elongation) are stimulated. Thorough evaluation of the behaviour of multiple transcriptional complexes during the early activation process has shown that the pathways by which activation proceeds for different genes may vary considerably, even in response to the same induction signal. RNA polymerase II recruitment is an important step that is involved in one of the pathways. RNA polymerase II recruitment is accompanied by the recruitment of a significant number of transcriptional coactivators as well as slight changes in the chromatin structure. The second pathway involves the stimulation of transcriptional elongation as its key step. The level of coactivator binding to the promoter shows almost no increase, whereas chromatin modification levels change significantly.
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Affiliation(s)
- Marina Yu Mazina
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Elena V Kovalenko
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Polina K Derevyanko
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Julia V Nikolenko
- Group of Studying an Association of Transcription and mRNA Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Aleksey N Krasnov
- Group of Studying an Association of Transcription and mRNA Transport, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Nadezhda E Vorobyeva
- Group of Transcriptional Complexes Dynamics, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia.
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13
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McDowell IC, Manandhar D, Vockley CM, Schmid AK, Reddy TE, Engelhardt BE. Clustering gene expression time series data using an infinite Gaussian process mixture model. PLoS Comput Biol 2018; 14:e1005896. [PMID: 29337990 PMCID: PMC5786324 DOI: 10.1371/journal.pcbi.1005896] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 01/26/2018] [Accepted: 11/25/2017] [Indexed: 12/24/2022] Open
Abstract
Transcriptome-wide time series expression profiling is used to characterize the cellular response to environmental perturbations. The first step to analyzing transcriptional response data is often to cluster genes with similar responses. Here, we present a nonparametric model-based method, Dirichlet process Gaussian process mixture model (DPGP), which jointly models data clusters with a Dirichlet process and temporal dependencies with Gaussian processes. We demonstrate the accuracy of DPGP in comparison to state-of-the-art approaches using hundreds of simulated data sets. To further test our method, we apply DPGP to published microarray data from a microbial model organism exposed to stress and to novel RNA-seq data from a human cell line exposed to the glucocorticoid dexamethasone. We validate our clusters by examining local transcription factor binding and histone modifications. Our results demonstrate that jointly modeling cluster number and temporal dependencies can reveal shared regulatory mechanisms. DPGP software is freely available online at https://github.com/PrincetonUniversity/DP_GP_cluster.
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Affiliation(s)
- Ian C. McDowell
- Computational Biology & Bioinformatics Graduate Program, Duke University, Durham, North Carolina, United States of America
- Center for Genomic & Computational Biology, Duke University, Durham, North Carolina, United States of America
| | - Dinesh Manandhar
- Computational Biology & Bioinformatics Graduate Program, Duke University, Durham, North Carolina, United States of America
- Center for Genomic & Computational Biology, Duke University, Durham, North Carolina, United States of America
| | - Christopher M. Vockley
- Center for Genomic & Computational Biology, Duke University, Durham, North Carolina, United States of America
- Department of Biostatistics & Bioinformatics, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Amy K. Schmid
- Center for Genomic & Computational Biology, Duke University, Durham, North Carolina, United States of America
- Biology Department, Duke University, Durham, North Carolina, United States of America
| | - Timothy E. Reddy
- Computational Biology & Bioinformatics Graduate Program, Duke University, Durham, North Carolina, United States of America
- Center for Genomic & Computational Biology, Duke University, Durham, North Carolina, United States of America
- Department of Biostatistics & Bioinformatics, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Barbara E. Engelhardt
- Department of Computer Science, Princeton University, Princeton, New Jersey, United States of America
- Center for Statistics and Machine Learning, Princeton University, Princeton, New Jersey, United States of America
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14
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Babaei Khalili M, Yazdanparast R, Nowrouzi A. Induction of transient cell cycle arrest by H 2 O 2 via modulation of ultradian oscillations of Hes1, Socs3, and p-Stat3 in fibroblast cells. J Cell Biochem 2017; 119:1453-1462. [PMID: 28771862 DOI: 10.1002/jcb.26306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 08/02/2017] [Indexed: 01/04/2023]
Abstract
Biological clocks, time-keeping systems, enable the living organisms to synchronize their biochemical processes with their environment. Among these molecular oscillators, ultradian oscillators have been identified with volatility less than 24 h. Transcription factor Hes1, a member of the basic Helix-loop-Helix (bHLH) protein family, has an oscillation duration of 2 h in vertebrates. Due to the pivotal role of oxidative stress in many human diseases, we evaluated the effect(s) of oxidative stress on Hes1 oscillator, its upstream regulators, and its downstream cell cycle regulators. NIH/3T3 mouse fibroblast cells were treated with sublethal (250 μM) and lethal (1000 μM) doses of H2 O2 for 30 min. H2 O2 generated a delay in p-Stat3 and Socs3 mRNAs followed by suppression of Hes1 protein. These events were accompanied by simultaneous upregulation of p21 and downregulation of cyclinD1, resulting in a temporary arrest of the cell cycle. In conclusion, the elimination of Hes1 protein oscillation by H2 O2 may represent a defense mechanism against oxidative stress in fibroblast cells.
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Affiliation(s)
| | - Razieh Yazdanparast
- Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran
| | - Azin Nowrouzi
- Department of Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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15
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Urbanek MO, Krzyzosiak WJ. Discriminating RNA variants with single-molecule allele-specific FISH. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2017; 773:230-241. [DOI: 10.1016/j.mrrev.2016.09.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 10/21/2022]
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16
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Salas EN, Shu J, Cserhati MF, Weeks DP, Ladunga I. Pluralistic and stochastic gene regulation: examples, models and consistent theory. Nucleic Acids Res 2016; 44:4595-609. [PMID: 26823500 PMCID: PMC4889914 DOI: 10.1093/nar/gkw042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2015] [Accepted: 01/12/2016] [Indexed: 12/17/2022] Open
Abstract
We present a theory of pluralistic and stochastic gene regulation. To bridge the gap between empirical studies and mathematical models, we integrate pre-existing observations with our meta-analyses of the ENCODE ChIP-Seq experiments. Earlier evidence includes fluctuations in levels, location, activity, and binding of transcription factors, variable DNA motifs, and bursts in gene expression. Stochastic regulation is also indicated by frequently subdued effects of knockout mutants of regulators, their evolutionary losses/gains and massive rewiring of regulatory sites. We report wide-spread pluralistic regulation in ≈800 000 tightly co-expressed pairs of diverse human genes. Typically, half of ≈50 observed regulators bind to both genes reproducibly, twice more than in independently expressed gene pairs. We also examine the largest set of co-expressed genes, which code for cytoplasmic ribosomal proteins. Numerous regulatory complexes are highly significant enriched in ribosomal genes compared to highly expressed non-ribosomal genes. We could not find any DNA-associated, strict sense master regulator. Despite major fluctuations in transcription factor binding, our machine learning model accurately predicted transcript levels using binding sites of 20+ regulators. Our pluralistic and stochastic theory is consistent with partially random binding patterns, redundancy, stochastic regulator binding, burst-like expression, degeneracy of binding motifs and massive regulatory rewiring during evolution.
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Affiliation(s)
- Elisa N Salas
- Department of Statistics, University of Nebraska, Lincoln, NE 68583-0963, USA Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0665, USA
| | - Jiang Shu
- Department of Statistics, University of Nebraska, Lincoln, NE 68583-0963, USA
| | - Matyas F Cserhati
- Department of Statistics, University of Nebraska, Lincoln, NE 68583-0963, USA
| | - Donald P Weeks
- Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0665, USA
| | - Istvan Ladunga
- Department of Statistics, University of Nebraska, Lincoln, NE 68583-0963, USA Department of Biochemistry, University of Nebraska, Lincoln, NE 68588-0665, USA
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17
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Stavreva DA, Hager GL. Chromatin structure and gene regulation: a dynamic view of enhancer function. Nucleus 2016; 6:442-8. [PMID: 26765055 DOI: 10.1080/19491034.2015.1107689] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Localized chromatin organization is now recognized as an important determinant of cell identity and developmental pathways. Recent studies have demonstrated that these epigenetic states are unexpectedly dynamic and malleable. In this Extra view we will highlight the transient nature of stimulus-induced enhancer accessibility and its importance for transcription regulation. Using glucocorticoid receptor (GR) as a model system we will discuss spatiotemporal relationships between receptor/chromatin interactions, lifetimes of the DNase I hypersensitivity sites (DHSs), long-range interactions, and gene regulation. We propose that differential temporal activation and utilization of distal regulatory elements plays a role in directing divergent stimulus-induced transcriptional programs.
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Affiliation(s)
- Diana A Stavreva
- a Laboratory of Receptor Biology and Gene Expression; National Cancer Institute; National Institutes of Health ; Bethesda , MD USA
| | - Gordon L Hager
- a Laboratory of Receptor Biology and Gene Expression; National Cancer Institute; National Institutes of Health ; Bethesda , MD USA
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18
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Wiley JW, Higgins GA, Athey BD. Stress and glucocorticoid receptor transcriptional programming in time and space: Implications for the brain-gut axis. Neurogastroenterol Motil 2016; 28:12-25. [PMID: 26690871 PMCID: PMC4688904 DOI: 10.1111/nmo.12706] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/20/2015] [Indexed: 12/25/2022]
Abstract
BACKGROUND Chronic psychological stress is associated with enhanced abdominal pain and altered intestinal barrier function that may result from a perturbation in the hypothalamic-pituitary-adrenal (HPA) axis. The glucocorticoid receptor (GR) exploits diverse mechanisms to activate or suppress congeneric gene expression, with regulatory variation associated with stress-related disorders in psychiatry and gastroenterology. PURPOSE During acute and chronic stress, corticotropin-releasing hormone drives secretion of adrenocorticotropic hormone from the pituitary, ultimately leading to the release of cortisol (human) and corticosterone (rodent) from the adrenal glands. Cortisol binds with the GR in the cytosol, translocates to the nucleus, and activates the NR3C1 (nuclear receptor subfamily 3, group C, member 1 [GR]) gene. This review focuses on the rapidly developing observations that cortisol is responsible for driving circadian and ultradian bursts of transcriptional activity in the CLOCK (clock circadian regulator) and PER (period circadian clock 1) gene families, and this rhythm is disrupted in major depressive disorder, bipolar disorder, and stress-related gastrointestinal and immune disorders. Glucocorticoid receptor regulates different sets of transcripts in a tissue-specific manner, through pulsatile waves of gene expression that includes occupancy of glucocorticoid response elements located within constitutively open spatial domains in chromatin. Emerging evidence supports a potentially pivotal role for epigenetic regulation of how GR interacts with other chromatin regulators to control the expression of its target genes. Dysregulation of the central and peripheral GR regulome has potentially significant consequences for stress-related disorders affecting the brain-gut axis.
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Affiliation(s)
- John W. Wiley
- Department of Internal Medicine, Division of Gastroenterology, University of Michigan Medical School, 1150 West Medical Center Drive, Ann Arbor, MI 48109, USA
| | - Gerald A. Higgins
- Department of Pharmacogenomic Science, Assurex Health, Inc., 6030 South Mason Montgomery Road, Mason, OH 45040, USA,Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA
| | - Brian D. Athey
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, 100 Washtenaw Avenue, Ann Arbor, MI 48109, USA
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19
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De Angelis RW, Maluf NK, Yang Q, Lambert JR, Bain DL. Glucocorticoid Receptor-DNA Dissociation Kinetics Measured in Vitro Reveal Exchange on the Second Time Scale. Biochemistry 2015; 54:5306-14. [PMID: 26267475 DOI: 10.1021/acs.biochem.5b00693] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The glucocorticoid receptor (GR) is a member of the steroid receptor family of ligand-activated transcription factors. Recent live cell imaging studies have revealed that interactions of GR with chromatin are highly dynamic, with average receptor residence times of only seconds. These findings were surprising because early kinetic studies found that GR-DNA interactions in vitro were much slower, having calculated residence times of minutes to hours. However, these latter analyses were conducted at a time when it was possible to work with only either partially purified holoreceptor or its purified but isolated DNA binding domain. Noting these limitations, we reexamined GR-DNA dissociation kinetics using a highly purified holoreceptor shown to be amenable to rigorous study. We first observe that GR-DNA interactions in vitro are not slow as previously thought but converge with in vivo behavior, having residence times of only seconds to tens of seconds. This rapid exchange is seen at six individual response elements and the multisite MMTV promoter used in live cell imaging. Second, GR dissociation rates are identical for all response elements. Thus, previously observed differences in receptor affinity toward these sequences are not due to differences in off rate but in on rate. Finally, dissociation kinetics are biphasic in character. A minimal kinetic model consistent with the data is that in which DNA-bound GR interconverts between states on a second time scale, with dissociation occurring via a multistep process. We speculate that receptor interconversion in this time frame can be recognized by the coregulatory proteins that interact with GR, leading to unique transcriptional responses.
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Affiliation(s)
- Rolando W De Angelis
- Department of Pharmaceutical Sciences and ‡Department of Pathology, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Nasib K Maluf
- Department of Pharmaceutical Sciences and ‡Department of Pathology, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - Qin Yang
- Department of Pharmaceutical Sciences and ‡Department of Pathology, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - James R Lambert
- Department of Pharmaceutical Sciences and ‡Department of Pathology, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
| | - David L Bain
- Department of Pharmaceutical Sciences and ‡Department of Pathology, University of Colorado Anschutz Medical Campus , Aurora, Colorado 80045, United States
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20
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Bain DL, De Angelis RW, Connaghan KD, Yang Q, Degala GD, Lambert JR. Dissecting Steroid Receptor Function by Analytical Ultracentrifugation. Methods Enzymol 2015; 562:363-89. [PMID: 26412661 DOI: 10.1016/bs.mie.2015.04.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Steroid receptors comprise a family of ligand-activated transcription factors. The members include the androgen receptor (AR), estrogen receptor (ER), glucocorticoid receptor (GR), mineralocorticoid receptor (MR), and progesterone receptor (PR). Each receptor controls distinct sets of genes associated with development, metabolism, and homeostasis. Although a qualitative understanding of how individual receptors mediate gene expression has come into focus, quantitative insight remains less clear. As a step toward delineating the physical mechanisms by which individual receptors activate their target genes, we have carried out a systematic dissection of receptor interaction energetics with their multisite regulatory elements. Analytical ultracentrifugation (AUC) has proved indispensable in these studies, in part by revealing the energetics of receptor self-association and its thermodynamic coupling to DNA binding. Here, we discuss these findings in the context of understanding specificity of receptor-mediated gene control. We first highlight the role of sedimentation velocity and sedimentation equilibrium in addressing receptor assembly state, and present a comparative analysis across the receptor family. We then use these results for understanding how receptors assemble at multisite regulatory elements, and hypothesize how these findings might play a role in receptor-specific gene regulation. Finally, we examine receptor behavior in a cellular context, with a view toward linking our in vitro studies with in vivo function.
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Affiliation(s)
- David L Bain
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.
| | - Rolando W De Angelis
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Keith D Connaghan
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Qin Yang
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Gregory D Degala
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - James R Lambert
- Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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21
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Stavreva DA, Coulon A, Baek S, Sung MH, John S, Stixova L, Tesikova M, Hakim O, Miranda T, Hawkins M, Stamatoyannopoulos JA, Chow CC, Hager GL. Dynamics of chromatin accessibility and long-range interactions in response to glucocorticoid pulsing. Genome Res 2015; 25:845-57. [PMID: 25677181 PMCID: PMC4448681 DOI: 10.1101/gr.184168.114] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Accepted: 02/05/2015] [Indexed: 12/20/2022]
Abstract
Although physiological steroid levels are often pulsatile (ultradian), the genomic effects of this pulsatility are poorly understood. By utilizing glucocorticoid receptor (GR) signaling as a model system, we uncovered striking spatiotemporal relationships between receptor loading, lifetimes of the DNase I hypersensitivity sites (DHSs), long-range interactions, and gene regulation. We found that hormone-induced DHSs were enriched within ± 50 kb of GR-responsive genes and displayed a broad spectrum of lifetimes upon hormone withdrawal. These lifetimes dictate the strength of the DHS interactions with gene targets and contribute to gene regulation from a distance. Our results demonstrate that pulsatile and constant hormone stimulations induce unique, treatment-specific patterns of gene and regulatory element activation. These modes of activation have implications for corticosteroid function in vivo and for steroid therapies in various clinical settings.
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Affiliation(s)
- Diana A Stavreva
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | - Antoine Coulon
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892, USA
| | - Songjoon Baek
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | - Myong-Hee Sung
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | - Sam John
- Laboratory of Genome Integrity, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | - Lenka Stixova
- Department of Molecular Cytology and Cytometry, Institute of Biophysics, Academy of Sciences of the Czech Republic, 612 65 Brno, Czech Republic
| | - Martina Tesikova
- Department of Biosciences, University of Oslo, 0316 Oslo, Norway
| | - Ofir Hakim
- The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 5290002, Israel
| | - Tina Miranda
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | - Mary Hawkins
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
| | | | - Carson C Chow
- Laboratory of Biological Modeling, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, Maryland 20892, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA
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22
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de Theije CC, Langen RCJ, Lamers WH, Gosker HR, Schols AMWJ, Köhler SE. Differential sensitivity of oxidative and glycolytic muscles to hypoxia-induced muscle atrophy. J Appl Physiol (1985) 2014; 118:200-11. [PMID: 25429096 DOI: 10.1152/japplphysiol.00624.2014] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Hypoxia as a consequence of acute and chronic respiratory disease has been associated with muscle atrophy. This study investigated the sensitivity of oxidative and glycolytic muscles to hypoxia-induced muscle atrophy. Male mice were exposed to 8% normobaric oxygen for up to 21 days. Oxidative soleus and glycolytic extensor digitorum longus (EDL) muscles were isolated, weighed, and assayed for expression profiles of the ubiquitin-proteasome system (UPS), the autophagy-lysosome pathway (ALP), and glucocorticoid receptor (GR) and hypoxia-inducible factor-1α (HIF1α) signaling. Fiber-type composition and the capillary network were investigated. Hypoxia-induced muscle atrophy was more prominent in the EDL than the soleus muscle. Although increased expression of HIF1α target genes showed that both muscle types sensed hypoxia, their adaptive responses differed. Atrophy consistently involved a hypoxia-specific effect (i.e., not attributable to a hypoxia-mediated reduction of food intake) in the EDL only. Hypoxia-specific activation of the UPS and ALP and increased expression of the glucocorticoid receptor (Gr) and its target genes were also mainly observed in the EDL. In the soleus, stimulation of gene expression of those pathways could be mimicked to a large extent by food restriction alone. Hypoxia increased the number of capillary contacts per fiber cross-sectional area in both muscles. In the EDL, this was due to type II fiber atrophy, whereas in the soleus the absolute number of capillary contacts increased. These responses represent two distinct modes to improve oxygen supply to muscle fibers, but may aggravate muscle atrophy in chronic obstructive pulmonary disease patients who have a predominance of type II fibers.
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Affiliation(s)
- C C de Theije
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Anatomy and Embryology, Maastricht University Medical Center+, Maastricht, The Netherlands; and
| | - R C J Langen
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Respiratory Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - W H Lamers
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Anatomy and Embryology, Maastricht University Medical Center+, Maastricht, The Netherlands; and
| | - H R Gosker
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Respiratory Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - A M W J Schols
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Respiratory Medicine, Maastricht University Medical Center+, Maastricht, The Netherlands
| | - S E Köhler
- NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Center+, Maastricht, The Netherlands; Department of Anatomy and Embryology, Maastricht University Medical Center+, Maastricht, The Netherlands; and
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23
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Abstract
The Dgcr14/Es2 gene is located in a chromosomal region the loss of which has been associated with DiGeorge syndrome, a cause of immunodeficiency, heart defects, and skeletal abnormalities. However, the role of DGCR14 protein remains to be elucidated. Here, I found that DGCR14 protein acts as a coactivator of RORγt in TH17 cells. Biochemical purification of the RORγ coregulator complex allowed me to identify the associated DGCR14 protein by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Overexpression of Dgcr14 mRNA enhanced RORγt-mediated transcriptional activity and facilitated TH17 cell differentiation. Furthermore, knockdown of Dgcr14 reduced Il17a mRNA expression. I also found that DGCR14 associated with ribosomal S6 kinase 2 (RSK2, also called RpS6ka3) and BAZ1B, both of which were recruited to the Il17a promoter during TH17 cell differentiation. Knockdown of Baz1b or RpS6ka3 also reduced Il17a mRNA expression, and Baz1b knockdown increased transcriptional suppressive histone marks (histone H3K9me3) on the Il17a promoter. My findings showed the roles of DGCR14, RSK2, and BAZ1B in the transcriptional regulation of Il17a mRNA during TH17 cell differentiation.
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24
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Huang L, Yuan Z, Liu P, Zhou T. Feedback-induced counterintuitive correlations of gene expression noise with bursting kinetics. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:052702. [PMID: 25493811 DOI: 10.1103/physreve.90.052702] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Indexed: 06/04/2023]
Abstract
Previous studies showed that a higher frequency of bursting results in lower expression noise whereas a larger size of bursting leads to higher expression noise. Here, we show counterintuitive correlations of expression noise with bursting kinetics due to the effect of feedback. Specifically, in the case of increasing the negative feedback strength but keeping the mean expression fixed, both the mean burst frequency and the mean burst size are invariant if the off-switching rate decreases, but expression noise is reduced; or the mean burst frequency is invariant and the burst size decreases if the transcription rate increases, but expression noise is amplified. Similarly, in the case of increasing the positive feedback strength but keeping the mean expression fixed, both the mean burst frequency and the mean burst size are invariant if the on-switching rate decreases; or the mean burst frequency increases and the mean burst size is invariant if the leakage rate decreases, but expression noise is amplified. In addition, we find that the previous conclusion that a larger burst size results in the lower noise in burst size needs to be modified in the case of feedback. Our results not only clarify the confusing relationship between feedback and expression noise but also imply that the mRNA or protein noise is no longer a simple sum of the internal noise and the promoter noise as shown in the case of no feedback.
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Affiliation(s)
- Lifang Huang
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, Peoples' Republic of China
| | - Zhanjiang Yuan
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, Peoples' Republic of China
| | - Peijiang Liu
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, Peoples' Republic of China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, Peoples' Republic of China
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25
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Zhang J, Zhou T. Promoter-mediated transcriptional dynamics. Biophys J 2014; 106:479-88. [PMID: 24461023 DOI: 10.1016/j.bpj.2013.12.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 11/24/2022] Open
Abstract
Genes in eukaryotic cells are typically regulated by complex promoters containing multiple binding sites for a variety of transcription factors, but how promoter dynamics affect transcriptional dynamics has remained poorly understood. In this study, we analyze gene models at the transcriptional regulation level, which incorporate the complexity of promoter structure (PS) defined as transcriptional exits (i.e., ON states of the promoter) and the transition pattern (described by a matrix consisting of transition rates among promoter activity states). We show that multiple exits of transcription are the essential origin of generating multimodal distributions of mRNA, but promoters with the same transition pattern can lead to multimodality of different modes, depending on the regulation of transcriptional factors. In turn, for similar mRNA distributions in the models, the mean ON or OFF time distributions may exhibit different characteristics, thus providing the supplemental information on PS. In addition, we demonstrate that the transcriptional noise can be characterized by a nonlinear function of mean ON and OFF times. These results not only reveal essential characteristics of promoter-mediated transcriptional dynamics but also provide signatures useful for inferring PS based on characteristics of transcriptional outputs.
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Affiliation(s)
- Jiajun Zhang
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China
| | - Tianshou Zhou
- Guangdong Province Key Laboratory of Computational Science, School of Mathematics and Computational Science, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China.
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26
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Wu Y, Wu Q, Beland FA, Ge P, Manjanatha MG, Fang JL. Differential effects of triclosan on the activation of mouse and human peroxisome proliferator-activated receptor alpha. Toxicol Lett 2014; 231:17-28. [PMID: 25193434 DOI: 10.1016/j.toxlet.2014.09.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Revised: 08/25/2014] [Accepted: 09/01/2014] [Indexed: 12/23/2022]
Abstract
Triclosan is an anti-bacterial agent used in many personal care products, household items, medical devices, and clinical settings. Liver tumors occur in mice exposed to triclosan, a response attributed to peroxisome proliferator-activated receptor alpha (PPARα) activation; however, the effects of triclosan on mouse and human PPARα have not been fully evaluated. We compared the effects of triclosan on mouse and human PPARα using PPARα reporter assays and on downstream events of PPARα activation using mouse hepatoma Hepa1c1c7 cells and human hepatoma HepG2 cells. PPARα transcriptional activity was increased by triclosan in a mouse PPARα reporter assay and decreased in a human PPARα reporter assay. Concentrations of triclosan inhibiting 50% cell growth were similar in both human and mouse hepatoma cells. Western blotting analysis showed that triclosan increased acyl-coenzyme A oxidase (ACOX1), a PPARα target, in Hepa1c1c7 cells but decreased the level in HepG2 cells. Treatment of Hepa1c1c7 cells with triclosan enhanced DNA synthesis and suppressed transforming growth factor beta-mediated apoptosis. This did not occur in HepG2 cells. These data demonstrate that triclosan had similar cytotoxicity in Hepa1c1c7 and HepG2 cells, but differential effects on the activation of PPARα, the expression of ACOX1, and downstream events including DNA synthesis and apoptosis.
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Affiliation(s)
- Yuanfeng Wu
- Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, HFT-110, Jefferson, AR 72079, USA
| | - Qiangen Wu
- Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, HFT-110, Jefferson, AR 72079, USA
| | - Frederick A Beland
- Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, HFT-110, Jefferson, AR 72079, USA
| | - Peter Ge
- Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, HFT-110, Jefferson, AR 72079, USA
| | - Mugimane G Manjanatha
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, Food and Drug Administration, Jefferson, AR 72079, USA
| | - Jia-Long Fang
- Division of Biochemical Toxicology, National Center for Toxicological Research, Food and Drug Administration, 3900 NCTR Road, HFT-110, Jefferson, AR 72079, USA.
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27
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Connaghan KD, Yang Q, Miura MT, Moody AD, Bain DL. Homologous steroid receptors assemble at identical promoter architectures with unique energetics of cooperativity. Proteins 2014; 82:2078-87. [PMID: 24648119 DOI: 10.1002/prot.24563] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 03/05/2014] [Accepted: 03/14/2014] [Indexed: 01/27/2023]
Abstract
Steroid receptors comprise a homologous family of ligand-activated transcription factors. The receptors bind largely identical response elements in vitro, yet regulate distinct gene networks in vivo. This paradox raises the issue of how transcriptional specificity is achieved, particularly if multiple receptor populations are competing for identical sites. Noting that receptor-DNA energetics are a primary force in driving transcriptional activity, differences in interaction energetics among the receptors might underlie receptor-specific transcriptional control. Thermodynamic dissections support this premise-upon assembling at an identical promoter architecture, individual receptors exhibit vast differences in cooperative and self-association energetics. More intriguingly, these parameters distribute in a way that mirrors the evolutionary divergence of the steroid receptor family. For example, the closely related progesterone and glucocorticoid receptors (PR and GR) display little or no self-association but strong intersite cooperativity, whereas the more distantly related estrogen receptor (ER-α) shows inverse behavior. These findings suggest that receptors view genomic promoter architectures as a collection of affinity landscapes; receptors select from this landscape via their unique interaction energetics. To test this idea, we analyzed the cooperative binding energetics of the above three receptors using an array of promoters. We find that cooperativity is not only receptor-specific but also highly promoter-specific. Thus PR shows maximal cooperativity at promoters with closely spaced and in phase binding sites. GR cooperativity is maintained over greater distances, is larger energetically, and shows markedly different phase dependency. Finally, ER-α appears incapable of cooperativity regardless of promoter architecture, consistent with its more distant phylogeny.
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Affiliation(s)
- Keith D Connaghan
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, Colorado, 80045
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Li X, Yang H, Huang S, Qiu Y. Histone deacetylase 1 and p300 can directly associate with chromatin and compete for binding in a mutually exclusive manner. PLoS One 2014; 9:e94523. [PMID: 24722339 PMCID: PMC3983199 DOI: 10.1371/journal.pone.0094523] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Accepted: 03/18/2014] [Indexed: 12/13/2022] Open
Abstract
Lysine acetyltransferases (KATs) and histone deacetylases (HDACs) are important epigenetic modifiers and dynamically cycled on active gene promoters to regulate transcription. Although HDACs are recruited to gene promoters and DNA hypersensitive sites through interactions with DNA binding factors, HDAC activities are also found globally in intergenic regions where DNA binding factors are not present. It is suggested that HDACs are recruited to those regions through other distinct, yet undefined mechanisms. Here we show that HDACs can be directly recruited to chromatin in the absence of other factors through direct interactions with both DNA and core histone subunits. HDACs interact with DNA in a non-sequence specific manner. HDAC1 and p300 directly bind to the overlapping regions of the histone H3 tail and compete for histone binding. Previously we show that p300 can acetylate HDAC1 to attenuate deacetylase activity. Here we have further mapped two distinct regions of HDAC1 that interact with p300. Interestingly, these regions of HDAC1 also associate with histone H3. More importantly, p300 and HDAC1 compete for chromatin binding both in vitro and in vivo. Therefore, the mutually exclusive associations of HDAC1/p300, p300/histone, and HDAC1/histone on chromatin contribute to the dynamic regulation of histone acetylation by balancing HDAC or KAT activity present at histones to reorganize chromatin structure and regulate transcription.
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Affiliation(s)
- Xuehui Li
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida, United States of America
| | - Hui Yang
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida, United States of America
| | - Suming Huang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, Florida, United States of America
| | - Yi Qiu
- Department of Anatomy and Cell Biology, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
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29
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Dynamic regulation of transcriptional states by chromatin and transcription factors. Nat Rev Genet 2013; 15:69-81. [PMID: 24342920 DOI: 10.1038/nrg3623] [Citation(s) in RCA: 333] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The interaction of regulatory proteins with the complex nucleoprotein structures that are found in mammalian cells involves chromatin reorganization at multiple levels. Mechanisms that support these transitions are complex on many timescales, which range from milliseconds to minutes or hours. In this Review, we discuss emerging concepts regarding the function of regulatory elements in living cells. We also explore the involvement of these dynamic and stochastic processes in the evolution of fluctuating transcriptional activity states that are now commonly reported in eukaryotic systems.
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Abstract
Nuclear receptors are transcription factors that regulate gene expression through the ligand-controlled recruitment of a diverse group of proteins known as coregulators. Most nuclear receptor coregulators function in large multi-protein complexes that modify chromatin and thereby regulate the transcription of target genes. Structural and functional studies are beginning to reveal how these complexes are assembled bringing together multiple functionalities that mediate: recruitment to specific genomic loci through interaction with transcription factors; recruitment of enzymatic activities that either modify or remodel chromatin and targeting the complexes to their chromatin substrate. These activities are regulated by post-translational modifications, alternative splicing and small signalling molecules. This review focuses on our current understanding of coregulator complexes and aims to highlight the common principles that are beginning to emerge.
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Affiliation(s)
- Christopher J. Millard
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Peter J. Watson
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - Louise Fairall
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
| | - John W.R. Schwabe
- Henry Wellcome Laboratories of Structural Biology, Department of Biochemistry, University of Leicester, Leicester, LE1 9HN. UK
- Correspondence to:
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Strehl C, Buttgereit F. Optimized glucocorticoid therapy: teaching old drugs new tricks. Mol Cell Endocrinol 2013; 380:32-40. [PMID: 23403055 DOI: 10.1016/j.mce.2013.01.026] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 01/31/2013] [Accepted: 01/31/2013] [Indexed: 01/01/2023]
Abstract
Glucocorticoids (GCs) are commonly used in the treatment of a wide range of rheumatic and other inflammatory diseases. They exert their potent anti-inflammatory and immunosuppressive effects primarily via so called genomic mechanisms, mediated by the cytosolic glucocorticoid receptor (cGR). This mechanism of GC action can be divided into the transactivation and the transrepression processes. However, also rapid effects of GCs exist which are mediated by specific and unspecific non-genomic mechanisms. A clinical relevance of this mode of GC action is assumed for effects mediated by membrane-bound glucocorticoid receptors, but detailed knowledge on the underlying mechanisms is still missing. Great efforts have been made in the past to diminish GC-induced adverse effects, thus improving the benefit/risk ratio of the drugs. Besides approaches to improve the treatment with conventional glucocorticoids currently available to clinicians, new innovative GCs or GC receptor ligands are also being developed.
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Affiliation(s)
- Cindy Strehl
- Department of Rheumatology and Clinical Immunology, Charité - Universitätsmedizin Berlin, Campus Mitte, Berlin, Germany.
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Dickmeis T, Weger BD, Weger M. The circadian clock and glucocorticoids--interactions across many time scales. Mol Cell Endocrinol 2013; 380:2-15. [PMID: 23707790 DOI: 10.1016/j.mce.2013.05.012] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 05/14/2013] [Accepted: 05/15/2013] [Indexed: 12/20/2022]
Abstract
Glucocorticoids are steroid hormones of the adrenal gland that are an integral component of the stress response and regulate many physiological processes, including metabolism and immune response. Their release into the blood is highly dynamic and occurs in about hourly pulses, the amplitude of which is modulated in a daytime dependent fashion. In addition, in many species seasonal changes in basal glucocorticoid levels have been reported. In their target tissues, glucocorticoids bind to cytoplasmic receptors of the nuclear receptor superfamily. Upon binding, these receptors regulate transcription in a highly dynamic fashion, which involves stochastic binding to regulatory DNA elements on a time scale of seconds and heat shock protein mediated receptor-ligand complex recycling within minutes. The glucocorticoid hormone system interacts with another highly dynamic system, the circadian clock. The circadian clock is an endogenous biological timing mechanism that allows organisms to anticipate regular daily changes in their environment. It regulates daily rhythms of glucocorticoid release by a variety of mechanisms, modulates glucocorticoid signaling and is itself influenced by glucocorticoids. Here, we discuss mechanisms, functions and interactions of the circadian and glucocorticoid systems across time scales ranging from seconds (DNA binding by transcriptional regulators) to years (seasonal rhythms).
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Affiliation(s)
- Thomas Dickmeis
- Institute of Toxicology and Genetics, Karlsruhe Institute of Technology (KIT), Campus Nord, Postfach 3640, D-76021 Karlsruhe, Germany.
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González-Miranda JM. On the effect of circadian oscillations on biochemical cell signaling by NF-κB. J Theor Biol 2013; 335:283-94. [PMID: 23820037 DOI: 10.1016/j.jtbi.2013.06.027] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 04/16/2013] [Accepted: 06/21/2013] [Indexed: 11/18/2022]
Abstract
We report the results of a numerical investigation of a mathematical model for NF-κB oscillations, described by a set of ordinary nonlinear differential equations, when perturbed by a circadian oscillation. The main result is that a circadian rhythm, even when it represents a weak perturbation, enhances the signaling capabilities of NF-κB oscillations. This is done by turning rest states into periodic oscillations, and periodic oscillations into quasiperiodic oscillations. Strong perturbations result in complex periodic oscillations and even in chaos. Circadian rhythms would then result in a NF-κB dynamics that is more complex than the simple oscillations and rest states, initially reported for this model. This renders it more amenable for information coding.
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Affiliation(s)
- J M González-Miranda
- Departamento de Física Fundamental, Universidad de Barcelona, Av. Diagonal 647, 08028 Barcelona, Spain.
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Bain DL, Connaghan KD, Maluf NK, Yang Q, Miura MT, De Angelis RW, Degala GD, Lambert JR. Steroid receptor-DNA interactions: toward a quantitative connection between energetics and transcriptional regulation. Nucleic Acids Res 2013; 42:691-700. [PMID: 24064251 PMCID: PMC3902896 DOI: 10.1093/nar/gkt859] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Steroid receptors comprise an evolutionarily conserved family of transcription factors. Although the qualitative aspects by which individual receptors regulate transcription are well understood, a quantitative perspective is less clear. This is primarily because receptor function is considerably more complex than that of classical regulatory factors such as phage or bacterial repressors. Here we discuss recent advances in placing receptor-specific transcriptional regulation on a more quantitative footing, specifically focusing on the role of macromolecular interaction energetics. We first highlight limitations and challenges associated with traditional approaches for assessing the role of energetics (more specifically, binding affinity) with functional outcomes such as transcriptional activation. We next demonstrate how rigorous in vitro measurements and straightforward interaction models quantitatively relate energetics to transcriptional activity within the cell, and follow by discussing why such an approach is unexpectedly effective in explaining complex functional behavior. Finally, we examine the implications of these findings for considering the unique gene regulatory properties of the individual receptors.
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Affiliation(s)
- David L Bain
- Department of Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA and Department of Pathology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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Grøntved L, John S, Baek S, Liu Y, Buckley JR, Vinson C, Aguilera G, Hager GL. C/EBP maintains chromatin accessibility in liver and facilitates glucocorticoid receptor recruitment to steroid response elements. EMBO J 2013; 32:1568-83. [PMID: 23665916 DOI: 10.1038/emboj.2013.106] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/10/2013] [Indexed: 01/22/2023] Open
Abstract
Mechanisms regulating transcription factor interaction with chromatin in intact mammalian tissues are poorly understood. Exploiting an adrenalectomized mouse model with depleted endogenous glucocorticoids, we monitor changes of the chromatin landscape in intact liver tissue following glucocorticoid injection. Upon activation of the glucocorticoid receptor (GR), proximal regions of activated and repressed genes are remodelled, and these remodelling events correlate with RNA polymerase II occupancy of regulated genes. GR is exclusively associated with accessible chromatin and 62% percent of GR-binding sites are occupied by C/EBPβ. At the majority of these sites, chromatin is preaccessible suggesting a priming function of C/EBPβ for GR recruitment. Disruption of C/EBPβ binding to chromatin results in attenuation of pre-programmed chromatin accessibility, GR recruitment and GR-induced chromatin remodelling specifically at sites co-occupied by GR and C/EBPβ. Collectively, we demonstrate a highly cooperative mechanism by which C/EBPβ regulates selective GR binding to the genome in liver tissue. We suggest that selective targeting of GR in other tissues is likely mediated by the combined action of cell-specific priming proteins and chromatin remodellers.
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Affiliation(s)
- Lars Grøntved
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, NIH, Bethesda, MD 20892, USA
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He F, Ma J. A spatial point pattern analysis in Drosophila blastoderm embryos evaluating the potential inheritance of transcriptional states. PLoS One 2013; 8:e60876. [PMID: 23593336 PMCID: PMC3621909 DOI: 10.1371/journal.pone.0060876] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2013] [Accepted: 03/04/2013] [Indexed: 01/10/2023] Open
Abstract
The Drosophila blastoderm embryo undergoes rapid cycles of nuclear division. This poses a challenge to genes that need to reliably sense the concentrations of morphogen molecules to form desired expression patterns. Here we investigate whether the transcriptional state of hunchback (hb), a target gene directly activated by the morphogenetic protein Bicoid (Bcd), exhibits properties indicative of inheritance between mitotic cycles. To achieve this, we build a dataset of hb transcriptional states at the resolution of individual nuclei in embryos at early cycle 14. We perform a spatial point pattern (SPP) analysis to evaluate the spatial relationships among the nuclei that have distinct numbers of hb gene copies undergoing active transcription in snapshots of embryos. Our statistical tests and simulation studies reveal properties of dispersed clustering for nuclei with both or neither copies of hb undergoing active transcription. Modeling of nuclear lineages from cycle 11 to cycle 14 suggests that these two types of nuclei can achieve spatial clustering when, and only when, the transcriptional states are allowed to propagate between mitotic cycles. Our results are consistent with the possibility where the positional information encoded by the Bcd morphogen gradient may not need to be decoded de novo at all mitotic cycles in the Drosophila blastoderm embryo.
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Affiliation(s)
- Feng He
- Division of Biomedical Informatics, Cincinnati Children's Research Foundation, Cincinnati, Ohio, United States of America
| | - Jun Ma
- Division of Biomedical Informatics, Cincinnati Children's Research Foundation, Cincinnati, Ohio, United States of America
- Division of Developmental Biology, Cincinnati Children's Research Foundation, Cincinnati, Ohio, United States of America
- * E-mail:
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Single-molecule imaging of transcription factor binding to DNA in live mammalian cells. Nat Methods 2013; 10:421-6. [PMID: 23524394 PMCID: PMC3664538 DOI: 10.1038/nmeth.2411] [Citation(s) in RCA: 344] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 02/26/2013] [Indexed: 02/07/2023]
Abstract
Imaging single fluorescent proteins in living mammalian cells is challenged by out-of-focus fluorescence excitation. To reduce out-of-focus fluorescence we developed reflected light-sheet microscopy (RLSM), a fluorescence microscopy method allowing selective plane illumination throughout the nuclei of living mammalian cells. A thin light sheet parallel to the imaging plane and close to the sample surface is generated by reflecting an elliptical laser beam incident from the top by 90° with a small mirror. The thin light sheet allows for an increased signal-to-background ratio superior to that in previous illumination schemes and enables imaging of single fluorescent proteins with up to 100-Hz time resolution. We demonstrated the single-molecule sensitivity of RLSM by measuring the DNA-bound fraction of glucocorticoid receptor (GR) and determining the residence times on DNA of various oligomerization states and mutants of GR and estrogen receptor-α (ER), which permitted us to resolve different modes of DNA binding of GR. We demonstrated two-color single-molecule imaging by observing the spatiotemporal colocalization of two different protein pairs. Our single-molecule measurements and statistical analysis revealed dynamic properties of transcription factors.
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