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Chiang IKN, Graus MS, Kirschnick N, Davidson T, Luu W, Harwood R, Jiang K, Li B, Wong YY, Moustaqil M, Lesieur E, Skoczylas R, Kouskoff V, Kazenwadel J, Arriola‐Martinez L, Sierecki E, Gambin Y, Alitalo K, Kiefer F, Harvey NL, Francois M. The blood vasculature instructs lymphatic patterning in a SOX7-dependent manner. EMBO J 2023; 42:e109032. [PMID: 36715213 PMCID: PMC9975944 DOI: 10.15252/embj.2021109032] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 12/15/2022] [Accepted: 12/22/2022] [Indexed: 01/31/2023] Open
Abstract
Despite a growing catalog of secreted factors critical for lymphatic network assembly, little is known about the mechanisms that modulate the expression level of these molecular cues in blood vascular endothelial cells (BECs). Here, we show that a BEC-specific transcription factor, SOX7, plays a crucial role in a non-cell-autonomous manner by modulating the transcription of angiocrine signals to pattern lymphatic vessels. While SOX7 is not expressed in lymphatic endothelial cells (LECs), the conditional loss of SOX7 function in mouse embryos causes a dysmorphic dermal lymphatic phenotype. We identify novel distant regulatory regions in mice and humans that contribute to directly repressing the transcription of a major lymphangiogenic growth factor (Vegfc) in a SOX7-dependent manner. Further, we show that SOX7 directly binds HEY1, a canonical repressor of the Notch pathway, suggesting that transcriptional repression may also be modulated by the recruitment of this protein partner at Vegfc genomic regulatory regions. Our work unveils a role for SOX7 in modulating downstream signaling events crucial for lymphatic patterning, at least in part via the transcriptional repression of VEGFC levels in the blood vascular endothelium.
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Affiliation(s)
- Ivy K N Chiang
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Matthew S Graus
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Nils Kirschnick
- European Institute for Molecular Imaging (EIMI)University of MünsterMünsterGermany
| | - Tara Davidson
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Winnie Luu
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Richard Harwood
- Sydney Microscopy and MicroanalysisUniversity of SydneySydneyNSWAustralia
| | - Keyi Jiang
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Bitong Li
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
| | - Yew Yan Wong
- The Genome Imaging CenterThe Centenary InstituteSydneyNSWAustralia
| | - Mehdi Moustaqil
- EMBL Australia Node in Single Molecule Science, and School of Medical SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Emmanuelle Lesieur
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaQLDAustralia
| | - Renae Skoczylas
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaQLDAustralia
| | - Valerie Kouskoff
- Division of Developmental Biology & MedicineThe University of ManchesterManchesterUK
| | - Jan Kazenwadel
- Centre for Cancer BiologyUniversity of South Australia and SA PathologyAdelaideSAAustralia
| | - Luis Arriola‐Martinez
- Centre for Cancer BiologyUniversity of South Australia and SA PathologyAdelaideSAAustralia
| | - Emma Sierecki
- EMBL Australia Node in Single Molecule Science, and School of Medical SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Yann Gambin
- EMBL Australia Node in Single Molecule Science, and School of Medical SciencesUniversity of New South WalesSydneyNSWAustralia
| | - Kari Alitalo
- Wihuri Research Institute and Translational Cancer Medicine Program, Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Friedmann Kiefer
- European Institute for Molecular Imaging (EIMI)University of MünsterMünsterGermany
| | - Natasha L Harvey
- Centre for Cancer BiologyUniversity of South Australia and SA PathologyAdelaideSAAustralia
| | - Mathias Francois
- The Centenary Institute, David Richmond Program for Cardio‐Vascular Research: Gene Regulation and Editing, Sydney Medical SchoolUniversity of SydneySydneyNSWAustralia
- The Genome Imaging CenterThe Centenary InstituteSydneyNSWAustralia
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2
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Parrello D, Vlasenok M, Kranz L, Nechaev S. Targeting the Transcriptome Through Globally Acting Components. Front Genet 2021; 12:749850. [PMID: 34603400 PMCID: PMC8481634 DOI: 10.3389/fgene.2021.749850] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Transcription is a step in gene expression that defines the identity of cells and its dysregulation is associated with diseases. With advancing technologies revealing molecular underpinnings of the cell with ever-higher precision, our ability to view the transcriptomes may have surpassed our knowledge of the principles behind their organization. The human RNA polymerase II (Pol II) machinery comprises thousands of components that, in conjunction with epigenetic and other mechanisms, drive specialized programs of development, differentiation, and responses to the environment. Parts of these programs are repurposed in oncogenic transformation. Targeting of cancers is commonly done by inhibiting general or broadly acting components of the cellular machinery. The critical unanswered question is how globally acting or general factors exert cell type specific effects on transcription. One solution, which is discussed here, may be among the events that take place at genes during early Pol II transcription elongation. This essay turns the spotlight on the well-known phenomenon of promoter-proximal Pol II pausing as a step that separates signals that establish pausing genome-wide from those that release the paused Pol II into the gene. Concepts generated in this rapidly developing field will enhance our understanding of basic principles behind transcriptome organization and hopefully translate into better therapies at the bedside.
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Affiliation(s)
- Damien Parrello
- Department of Biomedical Sciences, University of North Dakota School of Medicine, Grand Forks, ND, United States
| | - Maria Vlasenok
- Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Lincoln Kranz
- Department of Biomedical Sciences, University of North Dakota School of Medicine, Grand Forks, ND, United States
| | - Sergei Nechaev
- Department of Biomedical Sciences, University of North Dakota School of Medicine, Grand Forks, ND, United States
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3
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Kuphal S, Schneider N, Massoumi R, Hellerbrand C, Bosserhoff AK. UVB radiation represses CYLD expression in melanocytes. Oncol Lett 2018; 14:7262-7268. [PMID: 29344161 PMCID: PMC5754916 DOI: 10.3892/ol.2017.7120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 06/21/2017] [Indexed: 11/22/2022] Open
Abstract
CYLD lysine 63 deubiquitinase (CYLD) was originally identified as a tumor suppressor that is mutated in familial cylindromatosis. Unlike in cylindromatosis, downregulation of the deubiquitinase CYLD in melanoma, a highly aggressive tumor, is not caused by mutations in the CYLD gene, but rather by a constitutive and high expression of the snail family transcriptional repressor 1 (SNAIL1). A reduced CYLD level leads to B-cell lymphoma-3/p50/p52-dependent nuclear factor-κB activation, which in turn triggers the expression of genes such as cyclin D1 and N-cadherin. Elevated levels of cyclin D1 and N-cadherin promote melanoma proliferation and invasion. By analyzing the regulation of CYLD expression in melanocytes, the present study identified a signaling pathway that is regulated in response to ultraviolet B (UVB) radiation in melanocytes. UVB light leads to an extracellular signal-regulated kinase-mediated induction of SNAIL1 and subsequent downregulation of CYLD expression in normal human epithelial melanocytes. The UVB-mediated suppression of CYLD in melanocytes may have a key role in the reaction to UV stimuli, and may also potentially be involved in the early malignant transformation processes.
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Affiliation(s)
- Silke Kuphal
- Emil-Fischer-Center, Institute of Biochemistry, Friedrich Alexander University Erlangen-Nuremberg, D-91054 Erlangen, Germany
| | - Nadja Schneider
- Emil-Fischer-Center, Institute of Biochemistry, Friedrich Alexander University Erlangen-Nuremberg, D-91054 Erlangen, Germany
| | - Ramin Massoumi
- Department of Laboratory Medicine, Translational Cancer Research, Lund University, SE-221 00 Lund, Sweden
| | - Claus Hellerbrand
- Emil-Fischer-Center, Institute of Biochemistry, Friedrich Alexander University Erlangen-Nuremberg, D-91054 Erlangen, Germany
| | - Anja Katrin Bosserhoff
- Emil-Fischer-Center, Institute of Biochemistry, Friedrich Alexander University Erlangen-Nuremberg, D-91054 Erlangen, Germany
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4
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Patel T, Hobert O. Coordinated control of terminal differentiation and restriction of cellular plasticity. eLife 2017; 6. [PMID: 28422646 PMCID: PMC5397285 DOI: 10.7554/elife.24100] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Accepted: 03/23/2017] [Indexed: 01/17/2023] Open
Abstract
The acquisition of a specific cellular identity is usually paralleled by a restriction of cellular plasticity. Whether and how these two processes are coordinated is poorly understood. Transcription factors called terminal selectors activate identity-specific effector genes during neuronal differentiation to define the structural and functional properties of a neuron. To study restriction of plasticity, we ectopically expressed C. elegans CHE-1, a terminal selector of ASE sensory neuron identity. In undifferentiated cells, ectopic expression of CHE-1 results in activation of ASE neuron type-specific effector genes. Once cells differentiate, their plasticity is restricted and ectopic expression of CHE-1 no longer results in activation of ASE effector genes. In striking contrast, removal of the respective terminal selectors of other sensory, inter-, or motor neuron types now enables ectopically expressed CHE-1 to activate its ASE-specific effector genes, indicating that terminal selectors not only activate effector gene batteries but also control the restriction of cellular plasticity. Terminal selectors mediate this restriction at least partially by organizing chromatin. The chromatin structure of a CHE-1 target locus is less compact in neurons that lack their resident terminal selector and genetic epistasis studies with H3K9 methyltransferases suggest that this chromatin modification acts downstream of a terminal selector to restrict plasticity. Taken together, terminal selectors activate identity-specific genes and make non-identity-defining genes less accessible, thereby serving as a checkpoint to coordinate identity specification with restriction of cellular plasticity. DOI:http://dx.doi.org/10.7554/eLife.24100.001
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Affiliation(s)
- Tulsi Patel
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
| | - Oliver Hobert
- Department of Biological Sciences, Howard Hughes Medical Institute, Columbia University, New York, United States
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5
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Miao Z, Xu D, Cui M, Zhang Q. High mobility group protein DSP1 negatively regulates HSP70 transcription in Crassostrea hongkongensis. Biochem Biophys Res Commun 2016; 474:634-639. [PMID: 27154224 DOI: 10.1016/j.bbrc.2016.03.163] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 03/31/2016] [Indexed: 11/18/2022]
Abstract
HSP70 acts mostly as a molecular chaperone and plays important roles in facilitating the folding of nascent peptides as well as the refolding or degradation of the denatured proteins. Under stressed conditions, the expression level of HSP70 is upregulated significantly and rapidly, as is known to be achieved by various regulatory factors controlling the transcriptional level. In this study, a high mobility group protein DSP1 was identified by DNA-affinity purification from the nuclear extracts of Crassostrea hongkongensis using the ChHSP70 promoter as a bait. The specific interaction between the prokaryotically expressed ChDSP1 and the FITC-labeled ChHSP70 promoter was confirmed by EMSA analysis. ChDSP1 was shown to negatively regulate ChHSP70 promoter expression by Luciferase Reporter Assay in the heterologous HEK293T cells. Both ChHSP70 and ChDSP1 transcriptions were induced by either thermal or CdCl2 stress, while the accumulated expression peaks of ChDSP1 were always slightly delayed when compared with that of ChHSP70. This indicates that ChDSP1 is involved, very likely to exert its suppressive role, in the recovery of the ChHSP70 expression from the induced level to its original state. This study is the first to report negative regulator of HSP70 gene transcription, and provides novel insights into the mechanisms controlling heat shock protein expression.
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Affiliation(s)
- Zongyu Miao
- Institute of Hydrobiology, Department of Ecology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Delin Xu
- Institute of Hydrobiology, Department of Ecology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Miao Cui
- Institute of Hydrobiology, Department of Ecology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China
| | - Qizhong Zhang
- Institute of Hydrobiology, Department of Ecology, Key Laboratory of Eutrophication and Red Tide Prevention of Guangdong Higher Education Institutes, Jinan University, Guangzhou 510632, PR China.
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6
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Sevetson BR, Svaren J, Milbrandt J. A novel activation function for NAB proteins in EGR-dependent transcription of the luteinizing hormone beta gene. J Biol Chem 2000; 275:9749-57. [PMID: 10734128 DOI: 10.1074/jbc.275.13.9749] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The EGR1/NGFI-A transcription factor directly activates the luteinizing hormone beta (LHbeta) subunit promoter, and female mice lacking EGR1 are infertile due to LHbeta deficiency. The NGFI-A-binding proteins NAB1 and NAB2 are corepressors of EGR1/NGFI-A and of the related proteins EGR2/Krox20 and EGR3. Here we report that at certain promoters, including LHbeta, NAB proteins display a novel ability to stimulate EGR-directed transcription. NAB coactivation requires the conserved NCD2 protein domain, previously implicated in NAB corepression, is strictly dependent upon EGR binding to the LHbeta proximal promoter and is independent of EGR activation domains. Furthermore, we report that NAB-activated promoters such as LHbeta contain EGR consensus sites that are fewer in number and lower in binding affinity than those found at NAB-repressed promoters such as basic fibroblast growth factor. Analysis of mutant and synthetic promoters confirms that both the strength and multiplicity of EGR-binding sites influence the transcriptional outcome of NAB recruitment. These results suggest a novel means by which EGR target genes could be differentially regulated in cells where EGR and NAB proteins are coexpressed.
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Affiliation(s)
- B R Sevetson
- Departments of Pathology and Internal Medicine, Division of Laboratory Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA
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7
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Szabo SJ, Kim ST, Costa GL, Zhang X, Fathman CG, Glimcher LH. A novel transcription factor, T-bet, directs Th1 lineage commitment. Cell 2000; 100:655-69. [PMID: 10761931 DOI: 10.1016/s0092-8674(00)80702-3] [Citation(s) in RCA: 2635] [Impact Index Per Article: 109.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Naive T helper cells differentiate into two subsets, Th1 and Th2, each with distinct functions and cytokine profiles. Here, we report the isolation of T-bet, a Th1-specific T box transcription factor that controls the expression of the hallmark Th1 cytokine, IFNgamma. T-bet expression correlates with IFNgamma expression in Th1 and NK cells. Ectopic expression of T-bet both transactivates the IFNgamma gene and induces endogenous IFNgamma production. Remarkably, retroviral gene transduction of T-bet into polarized Th2 and Tc2 primary T cells redirects them into Th1 and Tc1 cells, respectively, as evidenced by the simultaneous induction of IFNgamma and repression of IL-4 and IL-5. Thus, T-bet initiates Th1 lineage development from naive Thp cells both by activating Th1 genetic programs and by repressing the opposing Th2 programs.
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Affiliation(s)
- S J Szabo
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115, USA
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8
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Sengupta PK, Ehrlich M, Smith BD. A methylation-responsive MDBP/RFX site is in the first exon of the collagen alpha2(I) promoter. J Biol Chem 1999; 274:36649-55. [PMID: 10593968 DOI: 10.1074/jbc.274.51.36649] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
DNA methylation inhibits transcription driven by the collagen alpha2(I) promoter and the 5' end of the gene in transient transfection and in vitro transcription assays. DNA-binding proteins in a unique family of ubiquitously expressed proteins, methylated DNA-binding protein (MDBP)/regulatory factor for X box (RFX), form specific complexes with a sequence overlapping the transcription start site of the collagen alpha2(I) gene. Complex formation increased when the CpG site at +7 base pairs from the transcription start site was methylated. The identity of the protein was demonstrated by co-migration and cross-competition for a characteristic slowly migrating doublet complex formed on MDBP/RFX recognition sequences and the collagen sequences by band shift assays. A RFX1-specific antibody supershifted the collagen DNA-protein complexes. Furthermore, in vitro translated RFX1 protein formed a specific complex with the collagen sequence that was also supershifted with the RFX1 antibody. MDBP/RFX displayed a higher affinity binding to the collagen sequence if the CpG at +7 was mutated in a manner similar to TpG. This same mutation within reporter constructs inhibited transcription in transfection and in vitro transcription assay. These results support the hypothesis that DNA methylation-induced inactivation of collagen alpha2(I) gene transcription is mediated, in part, by increased binding of MDBP/RFX to the first exon in response to methylation in this region.
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Affiliation(s)
- P K Sengupta
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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9
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Stein D, Goltz JS, Jurcsak J, Stevens L. The Dorsal-related immunity factor (Dif) can define the dorsal-ventral axis of polarity in the Drosophila embryo. Development 1998; 125:2159-69. [PMID: 9570779 DOI: 10.1242/dev.125.11.2159] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
In Drosophila embryos, dorsal-ventral polarity is defined by a signal transduction pathway that regulates nuclear import of the Dorsal protein. Dorsal protein's ability to act as a transcriptional activator of some zygotic genes and a repressor of others defines structure along the dorsal-ventral axis. Dorsal is a member of a group of proteins, the Rel-homologous proteins, whose activity is regulated at the level of nuclear localization. Dif, a more recently identified Drosophila Rel-homologue, has been proposed to act as a mediator of the immune response in Drosophila. In an effort to understand the function and regulation of Rel-homologous proteins in Drosophila, we have expressed Dif protein in Drosophila embryos derived from dorsal mutant mothers. We found that the Dif protein was capable of restoring embryonic dorsal-ventral pattern elements and was able to define polarity correctly with respect to the orientation of the egg shell. This, together with the observation that the ability of Dif to restore a dorsal-ventral axis depended on the signal transduction pathway that normally regulates Dorsal, suggests that Dif protein formed a nuclear concentration gradient similar to that seen for Dorsal. By studying the expression of Dorsal target genes we found that Dif could activate the zygotic genes that Dorsal activates and repress the genes repressed by Dorsal. Differences in the expression of these target genes, as well as the results from interaction studies carried out in yeast, suggest that Dif is not capable of synergizing with the basic helix-loop-helix transcription factors with which Dorsal normally interacts, and thereby lacks an important component of Dorsal-mediated pattern formation.
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Affiliation(s)
- D Stein
- Department of Molecular Genetics and Department of Developmental and Molecular Biology, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, NY 10461, USA.
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10
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Thatcher JW, Shaw JM, Dickinson WJ. Marginal fitness contributions of nonessential genes in yeast. Proc Natl Acad Sci U S A 1998; 95:253-7. [PMID: 9419362 PMCID: PMC18192 DOI: 10.1073/pnas.95.1.253] [Citation(s) in RCA: 145] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Analysis of the complete genome sequence of Saccharomyces cerevisiae confirms and extends earlier evidence that a majority of yeast genes are not essential, at least under laboratory conditions. Many fail to yield a discernible mutant phenotype even when disrupted. Genes not subject to natural selection would accumulate inactivating mutations, so these "cryptic" genes must have functions that are overlooked by the standard methods of yeast genetics. Two explanations seem possible: (i) They have important functions only in environments not yet duplicated in the laboratory and would have conditional phenotypes if tested appropriately. (ii) They make small, but significant, contributions to fitness even under routine growth conditions, but the effects are not large enough to be detected by conventional methods. We have tested the second "marginal benefit" hypothesis by measuring the fitnesses of a random collection of disruption mutants in direct competition with their wild-type progenitor. A substantial majority of mutant strains that lack obvious defects nevertheless are at a significant selective disadvantage just growing on rich medium under normal conditions. This result has important implications for efforts to understand the functions of novel genes revealed by sequencing projects.
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Affiliation(s)
- J W Thatcher
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
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11
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Volpe F, Clatworthy J, Kaptein A, Maschera B, Griffin AM, Ray K. The IL1 receptor accessory protein is responsible for the recruitment of the interleukin-1 receptor associated kinase to the IL1/IL1 receptor I complex. FEBS Lett 1997; 419:41-4. [PMID: 9426216 DOI: 10.1016/s0014-5793(97)01426-9] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Following interleukin-1 (IL1) stimulation, an IL1 receptor associated kinase (IRAK) is rapidly recruited to the receptor complex. However, it is not understood if IRAK is able to interact directly with the intracellular portion of the IL1-RI or if its recruitment is mediated by a different molecule. Using the yeast two-hybrid system, we have analysed possible protein-protein interactions between IRAK, IL1-RI and IL1-RAcP. We found that IRAK is able to interact with the equivalent cytoplasmic region of the IL1-RAcP but is unable to interact with the cytoplasmic region of the IL1-RI. Immunoprecipitation of the IL1-RAcP followed by Western blot analysis using anti-IRAK antibodies revealed that IRAK co-precipitated with the IL1-RAcP. We propose that, in non-stimulated cells, IRAK is bound to the IL1-RAcP and therefore, following IL1 stimulation, both molecules are recruited simultaneously to the ILI-RI complex.
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Affiliation(s)
- F Volpe
- Glaxo Wellcome, Cell Biology Unit, Stevenage, UK.
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12
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Hemavathy K, Meng X, Ip YT. Differential regulation of gastrulation and neuroectodermal gene expression by Snail in the Drosophila embryo. Development 1997; 124:3683-91. [PMID: 9367424 DOI: 10.1242/dev.124.19.3683] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The initiation of mesoderm differentiation in the Drosophila embryo requires the gene products of twist and snail. In either mutant, the ventral cell invagination during gastrulation is blocked and no mesoderm-derived tissue is formed. One of the functions of Snail is to repress neuroectodermal genes and restrict their expressions to the lateral regions. The derepression of the neuroectodermal genes into the ventral region in snail mutant is a possible cause of defects in gastrulation and in mesoderm differentiation. To investigate such possibility, we analysed a series of snail mutant alleles. We found that different neuroectodermal genes respond differently in various snail mutant background. Due to the differential response of target genes, one of the mutant alleles, V2, that has reduced Snail function showed an intermediate phenotype. In V2 embryos, neuroectodermal genes, such as single-minded and rhomboid, are derepressed while ventral invagination proceeds normally. However, the differentiation of these invaginated cells into mesodermal lineage is disrupted. The results suggest that the establishment of mesodermal cell fate requires the proper restriction of neuroectodermal genes, while the ventral cell movement is independent of the expression patterns of these genes. Together with the data showing that the expression of some ventral genes disappear in snail mutants, we propose that Snail may repress or activate another set of target genes that are required specifically for gastrulation.
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Affiliation(s)
- K Hemavathy
- Program in Molecular Medicine, Department of Cell Biology, University of Massachusetts Medical Center, Worcester 01605, USA
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13
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Katan Y, Agami R, Shaul Y. The transcriptional activation and repression domains of RFX1, a context-dependent regulator, can mutually neutralize their activities. Nucleic Acids Res 1997; 25:3621-8. [PMID: 9278482 PMCID: PMC146931 DOI: 10.1093/nar/25.18.3621] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
EP is a DNA element found in regulatory regions of viral and cellular genes. While being a key functional element in viral enhancers, EP has no intrinsic enhancer activity but can stimulate or silence transcription in a context-dependent manner. The EP element is bound by RFX1, which belongs to a novel, evolutionarily conserved protein family. In an attempt to decipher the mechanism by which EP regulates transcription, the intrinsic transcriptional activity of RFX1 was investigated. A functional dissection of RFX1, by analysis of deletion mutants and chimeric proteins, identified several regions with independent transcriptional activity. An activation domain containing a glutamine-rich region is found in the N-terminal half of RFX1, while a region with repressor activity overlaps the C-terminal dimerization domain. In RFX1 these activities were mutually neutralized, producing a nearly inactive transcription factor. This neutralization effect was reproduced by fusing RFX1 sequences to a heterologous DNA-binding domain. We propose that relief of self-neutralization may allow RFX1 to act as a dual-function regulator via its activation and repression domains, accounting for the context-dependent activity of EP.
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Affiliation(s)
- Y Katan
- Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
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14
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MacDonald E, Kobilka BK, Scheinin M. Gene targeting--homing in on alpha 2-adrenoceptor-subtype function. Trends Pharmacol Sci 1997; 18:211-9. [PMID: 9227000 DOI: 10.1016/s0165-6147(97)01063-8] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The alpha-adrenoceptor was subdivided into three subtypes: alpha 2A-, alpha 2B- and alpha 2C-adrenoceptors almost ten years ago. Since then, the search has been on to discover and develop subtype-selective agonists and antagonists, but as yet no major breakthrough has been made. In the past year, several strains of genetically engineered mice have become available, either overexpressing, totally lacking or expressing heavily modified alpha 2-adrenoceptor subtypes. Ewen MacDonald, Brian Kobilka and Mika Scheinin describe how these mice may be utilized to elucidate the physiological functions of the receptor subtypes and the properties of future subtype-selective drugs.
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Affiliation(s)
- E MacDonald
- Department of Pharmacology and Toxicology, Universit of Kuopio, Finland
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15
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Ghersa P, Whelan J, Cambet Y, DeLamarter JF, Hooft van Huijsduijnen R. Distamycin prolongs E-selectin expression by interacting with a specific NF-kappaB-HMG-I(Y) binding site in the promoter. Nucleic Acids Res 1997; 25:339-46. [PMID: 9016563 PMCID: PMC146425 DOI: 10.1093/nar/25.2.339] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The E-selectin cell adhesion protein plays a critical role in mediating adherence of leukocytes to endothelium at sites of inflammation. Cytokine-induced E-selectin expression on the surface of endothelial cells is transient; mRNA expression peaks at 3-4 h after induction and returns to basal levels within 24 h. The mechanism for this transcriptional down-modulation is not known. Promoter binding factors responsible for induced gene expression include NF-kappaB, which binds at three sites within the E-selectin promoter, and HMG-I(Y), which binds to the A/T-rich core found at the centre of these binding sites. Distamycin is an antibiotic that also binds A/T-rich DNA and inhibits HMG-I(Y) DNA binding. To study the role of HMG-I(Y) in E-selectin expression, we have examined the effect of distamycin on the cytokine-induced E-selectin expression cycle. We found that distamycin prolonged E-selectin expression, both by sustaining mRNA transcription and by extending the transcript's half-life. The distamycin effect on transcription was mediated through one of the three NF-kappaB-HMG-I(Y) binding sites (NF-kappaBII) within the promoter. This suggests that the NF-kappaB-HMG-I(Y) complex interacting at the NF-kappaBII site plays a role not only in cytokine induction of E-selectin expression, but also in its down-modulation.
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Affiliation(s)
- P Ghersa
- Geneva Biomedical Research Institute, 14, Chemin des Aulx, Case Postale 674, 1228 Plan-les-Ouates, Geneva, Switzerland.
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16
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Schoenherr CJ, Paquette AJ, Anderson DJ. Identification of potential target genes for the neuron-restrictive silencer factor. Proc Natl Acad Sci U S A 1996; 93:9881-6. [PMID: 8790425 PMCID: PMC38523 DOI: 10.1073/pnas.93.18.9881] [Citation(s) in RCA: 347] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The neuron-restrictive silencer factor (NRSF) represses transcription of several neuronal genes in nonneuronal cells by binding to a 21-bp element called the neuron-restrictive silencer element (NRSE). We have performed data base searches with a composite NRSE to identify additional candidate NRSF target genes. Twenty-two more genes, 17 of which are expressed mainly in neurons, were found to contain NRSE-like sequences. Many of these putative NRSEs bound NRSF in vitro and repressed transcription in vivo. Most of the neuronal genes identified contribute to the basic structural or functional properties of neurons. However, two neuronal transcription factor genes contain NRSEs, suggesting that NRSF may repress neuronal differentiation both directly and indirectly. Functional NRSEs were also found in several nonneuronal genes, implying that NRSF may play a broader role than originally anticipated.
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Affiliation(s)
- C J Schoenherr
- Division of Biology 216-76, California Institute of Technology, Pasadena 91125, USA
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17
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Loh C, Carew JA, Kim J, Hogan PG, Rao A. T-cell receptor stimulation elicits an early phase of activation and a later phase of deactivation of the transcription factor NFAT1. Mol Cell Biol 1996; 16:3945-54. [PMID: 8668212 PMCID: PMC231391 DOI: 10.1128/mcb.16.7.3945] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
We show here that NFAT1 is rapidly activated, then slowly deactivated, by stimulation of T cells through their antigen receptor. Within minutes of T-cell receptor stimulation, NFAT1 is dephosphorylated, translocates from the cytoplasm into the nucleus, and shows an increase in its ability to bind to DNA. These changes are dependent on calcium mobilization and calcineurin activation, since they are also elicited by ionomycin and are blocked by the immunosuppressive drug cyclosporin A. After several hours of T-cell receptor stimulation, the majority of the NFAT1 in the cell reverts to its original phosphorylated form, reappears in the cytoplasm, and again displays a low affinity for DNA. Deactivation of NFAT1 is facilitated by phorbol 12-myristate 13-acetate and inhibitors of capacitative calcium entry and most likely reflects the slow return of intracellular free calcium concentrations towards resting levels. Our results suggest that calcineurin-dependent signalling pathways mediate the early activation of NFAT1, while phorbol 12-myristate 13-acetate-dependent feedback pathways contribute to the late deactivation. Persistent NFAT-dependent cytokine gene transcription in activated T cells may be mediated by other NFAT family proteins in addition to NFAT1 during the immune response.
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Affiliation(s)
- C Loh
- Division of Cellular and Molecular Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA
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18
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Donda A, Schulz M, Bürki K, De Libero G, Uematsu Y. Identification and characterization of a human CD4 silencer. Eur J Immunol 1996; 26:493-500. [PMID: 8617322 DOI: 10.1002/eji.1830260232] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Using transgenic mice, we have identified a human CD4 silencer contained within a 484-bp fragment in the first intron of the CD4 gene. Further experiments have mapped a lineage-specific silencing activity to a region of 190 bp. This region contains two protein-binding sites detected by deoxyribonuclease I footprinting analyses. Tested in transient transfection assays, these two DNA elements showed significant silencing activity restricted to the CD8 phenotype. In CD4 cells, either no clear effect (FP I) or strong enhancing activity (FP II) was observed by transient transfection assays. Despite the lineage-specific activity of these two elements, electrophoretic mobility shift assays (EMSA) showed similar levels of protein binding to the silencer element FP I in CD4 and CD8 T cells. Base substitutions in the FP I fragment abolished the silencing activity in transfected CD8 cells as well as the protein binding in EMSA, suggesting an important role of this protein-DNA interaction in CD4 gene regulation.
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Affiliation(s)
- A Donda
- Experimental Immuology, Department of Research, University Hospital, Basel, Switzerland
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19
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Affiliation(s)
- D Thanos
- Harvard University, Department of Molecular and Cellular Biology, Cambridge, Massachusetts 02138
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