1
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Posadas N, Conaco C. Gene networks governing the response of a calcareous sponge to future ocean conditions reveal lineage-specific XBP1 regulation of the unfolded protein response. Ecol Evol 2024; 14:e11652. [PMID: 38952658 PMCID: PMC11214833 DOI: 10.1002/ece3.11652] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 06/12/2024] [Accepted: 06/14/2024] [Indexed: 07/03/2024] Open
Abstract
Marine sponges are predicted to be winners in the future ocean due to their exemplary adaptive capacity. However, while many sponge groups exhibit tolerance to a wide range of environmental insults, calcifying sponges may be more susceptible to thermo-acidic stress. To describe the gene regulatory networks that govern the stress response of the calcareous sponge, Leucetta chagosensis (class Calcarea, order Clathrinida), individuals were subjected to warming and acidification conditions based on the climate models for 2100. Transcriptome analysis and gene co-expression network reconstruction revealed that the unfolded protein response (UPR) was activated under thermo-acidic stress. Among the upregulated genes were two lineage-specific homologs of X-box binding protein 1 (XBP1), a transcription factor that activates the UPR. Alternative dimerization between these XBP1 gene products suggests a clathrinid-specific mechanism to reversibly sequester the transcription factor into an inactive form, enabling the rapid regulation of pathways linked to the UPR in clathrinid calcareous sponges. Our findings support the idea that transcription factor duplication events may refine evolutionarily conserved molecular pathways and contribute to ecological success.
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Affiliation(s)
- Niño Posadas
- Marine Science Institute, University of the Philippines DilimanQuezon CityPhilippines
- Present address:
Centre for Chromosome Biology, School of Biological and Chemical SciencesUniversity of GalwayGalwayIreland
| | - Cecilia Conaco
- Marine Science Institute, University of the Philippines DilimanQuezon CityPhilippines
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2
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Saavedra Núñez G, González-Villanueva E, Ramos P. Floral Development on Vitis vinifera Is Associated with MADS-Box Transcription Factors through the Transcriptional Regulation of VviZIP3. PLANTS (BASEL, SWITZERLAND) 2023; 12:3322. [PMID: 37765487 PMCID: PMC10535425 DOI: 10.3390/plants12183322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 09/11/2023] [Accepted: 09/15/2023] [Indexed: 09/29/2023]
Abstract
Several grapevine (Vitis vinifera L.) cultivars show a tendency to develop parthenocarpic seedless grapes, affecting fruit yield and quality. This reproductive disorder originates in defective ovule fertilization due to a failure in pollen tube growth. Zinc (Zn) is a crucial trace element, playing a vital role in various physiological and metabolic processes. It is particularly essential for the healthy growth of flowers and fruits. Insufficient zinc has been suggested as a potential reason for issues in this development process. This microelement is taken up through a mechanism that involves transporters, including the ZRT-IRT-like protein (ZIP) gene family, associated with the influx of Zn into the cell. In grapevines, 20 genes for ZIP-type transporters have been described. In this study, we analyzed the expression pattern of VviZIP3 during flower development and employ transgenic methods to assess its transcriptional regulation. Furthermore, through computational examination of the promoter region, we identified two CArG boxes, recognized as responsive elements to MADS transcription factors. These factors play a key role in shaping various components of a flower, such as pollen. Our investigation of the VviZIP3 promoter confirms the functionality of these CArG boxes. Overall, our results suggest that the increased expression of VviZIP3 during flowering is likely under the influence of MADS transcription factors.
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Affiliation(s)
- Germán Saavedra Núñez
- Instituto de Ciencias Biológicas, Universidad de Talca, Talca 3460787, Chile; (G.S.N.); (E.G.-V.)
| | | | - Patricio Ramos
- Instituto de Ciencias Biológicas, Universidad de Talca, Talca 3460787, Chile; (G.S.N.); (E.G.-V.)
- Vicerrectoría de Investigación y Postgrado, Universidad Católica del Maule, Talca 3480112, Chile
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3
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Martinez-Corral R, Park M, Biette KM, Friedrich D, Scholes C, Khalil AS, Gunawardena J, DePace AH. Transcriptional kinetic synergy: A complex landscape revealed by integrating modeling and synthetic biology. Cell Syst 2023; 14:324-339.e7. [PMID: 37080164 PMCID: PMC10472254 DOI: 10.1016/j.cels.2023.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 08/22/2022] [Accepted: 02/10/2023] [Indexed: 04/22/2023]
Abstract
Transcription factors (TFs) control gene expression, often acting synergistically. Classical thermodynamic models offer a biophysical explanation for synergy based on binding cooperativity and regulated recruitment of RNA polymerase. Because transcription requires polymerase to transition through multiple states, recent work suggests that "kinetic synergy" can arise through TFs acting on distinct steps of the transcription cycle. These types of synergy are not mutually exclusive and are difficult to disentangle conceptually and experimentally. Here, we model and build a synthetic circuit in which TFs bind to a single shared site on DNA, such that TFs cannot synergize by simultaneous binding. We model mRNA production as a function of both TF binding and regulation of the transcription cycle, revealing a complex landscape dependent on TF concentration, DNA binding affinity, and regulatory activity. We use synthetic TFs to confirm that the transcription cycle must be integrated with recruitment for a quantitative understanding of gene regulation.
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Affiliation(s)
| | - Minhee Park
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA
| | - Kelly M Biette
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Dhana Friedrich
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Clarissa Scholes
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Ahmad S Khalil
- Biological Design Center, Boston University, Boston, MA 02215, USA; Department of Biomedical Engineering, Boston University, Boston, MA 02215, USA; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Jeremy Gunawardena
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA
| | - Angela H DePace
- Department of Systems Biology, Harvard Medical School, Boston, MA 02115, USA.
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4
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Tsuji A, Yamashita H, Hisatomi O, Abe M. Dimerization processes for light-regulated transcription factor Photozipper visualized by high-speed atomic force microscopy. Sci Rep 2022; 12:12903. [PMID: 35941201 PMCID: PMC9359980 DOI: 10.1038/s41598-022-17228-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 07/21/2022] [Indexed: 11/24/2022] Open
Abstract
Dimerization is critical for transcription factors (TFs) to bind DNA and regulate a wide variety of cellular functions; however, the molecular mechanisms remain to be completely elucidated. Here, we used high-speed atomic force microscopy (HS-AFM) to observe the dimerization process for a photoresponsive TF Photozipper (PZ), which consists of light–oxygen–voltage-sensing (LOV) and basic-region-leucine-zipper (bZIP) domains. HS-AFM visualized not only the oligomeric states of PZ molecules forming monomers and dimers under controlled dark–light conditions but also the domain structures within each molecule. Successive AFM movies captured the dimerization process for an individual PZ molecule and the monomer–dimer reversible transition during dark–light cycling. Detailed AFM images of domain structures in PZ molecules demonstrated that the bZIP domain entangled under dark conditions was loosened owing to light illumination and fluctuated around the LOV domain. These observations revealed the role of the bZIP domain in the dimerization processes of a TF.
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Affiliation(s)
- Akihiro Tsuji
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
| | - Hayato Yamashita
- Graduate School of Engineering Science, Osaka University, Osaka, Japan.
| | - Osamu Hisatomi
- Graduate School of Science, Osaka University, Osaka, Japan
| | - Masayuki Abe
- Graduate School of Engineering Science, Osaka University, Osaka, Japan
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5
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Huang J, Dai W, Xiao D, Xiong Q, Liu C, Hu J, Ge F, Yu X, Li S. Acetylation-dependent SAGA complex dimerization promotes nucleosome acetylation and gene transcription. Nat Struct Mol Biol 2022; 29:261-273. [PMID: 35301489 DOI: 10.1038/s41594-022-00736-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 11/30/2021] [Accepted: 02/02/2022] [Indexed: 11/09/2022]
Abstract
Cells reprogram their transcriptomes to adapt to external conditions. The SAGA (Spt-Ada-Gcn5 acetyltransferase) complex is a highly conserved transcriptional coactivator that plays essential roles in cell growth and development, in part by acetylating histones. Here, we uncover an autoregulatory mechanism of the Saccharomyces cerevisiae SAGA complex in response to environmental changes. Specifically, the SAGA complex acetylates its Ada3 subunit at three sites (lysines 8, 14 and 182) that are dynamically deacetylated by Rpd3. The acetylated Ada3 lysine residues are bound by bromodomains within SAGA subunits Gcn5 and Spt7 that synergistically facilitate formation of SAGA homo-dimers. Ada3-mediated dimerization is enhanced when cells are grown under sucrose or under phosphate-starvation conditions. Once dimerized, SAGA efficiently acetylates nucleosomes, promotes gene transcription and enhances cell resistance to stress. Collectively, our work reveals a mechanism for regulation of SAGA structure and activity and provides insights into how cells adapt to environmental conditions.
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Affiliation(s)
- Junhua Huang
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China
| | - Wenjing Dai
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China
| | - Duncheng Xiao
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China
| | - Qian Xiong
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Cuifang Liu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Jie Hu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Feng Ge
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Xilan Yu
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China.
| | - Shanshan Li
- State Key Laboratory of Biocatalysis and Enzyme Engineering, College of Life Sciences, Hubei University, Wuhan, China.
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6
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Promoter Polymorphisms of the Canine SCL11A1 Gene are Correlated with Susceptibility to Canine Leishmaniosis. ACTA VET-BEOGRAD 2020. [DOI: 10.2478/acve-2020-0023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Abstract
In enzootic areas the prevalence estimates of canine leishmaniosis are high whereas only a proportion of dogs exhibit the clinical disease, thus implying a role of host genetics. The type of the triggered immune response remains a crucial determining factor for the diverse outcome of this parasitosis. The Solute Carrier Family 11 member 1 (SLC11A1) is a protein, which plays a central role in macrophage function and is implicated in the regulation of the immune response. An extended study with 73 resistant and 75 susceptible to Leishmania dogs was conducted. A fragment of the promoter region of the canine SLC11A1 gene was amplified and digested providing the different genotypes for three previously recorded single-nucleotide polymorphisms (SNPs) (SNP1 T151C, SNP2 Α180G, SNP3 G318A) for each animal. Statistical analyses revealed that SNP2 Α180G in heterozygosity (AG) as well as SNP3 G318A in homozygosity (AA) are correlated with susceptibility to canine leishmaniosis.
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7
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Structural basis for the complex DNA binding behavior of the plant stem cell regulator WUSCHEL. Nat Commun 2020; 11:2223. [PMID: 32376862 PMCID: PMC7203112 DOI: 10.1038/s41467-020-16024-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 04/08/2020] [Indexed: 11/09/2022] Open
Abstract
Stem cells are one of the foundational evolutionary novelties that allowed the independent emergence of multicellularity in the plant and animal lineages. In plants, the homeodomain (HD) transcription factor WUSCHEL (WUS) is essential for the maintenance of stem cells in the shoot apical meristem. WUS has been reported to bind to diverse DNA motifs and to act as transcriptional activator and repressor. However, the mechanisms underlying this remarkable behavior have remained unclear. Here, we quantitatively delineate WUS binding to three divergent DNA motifs and resolve the relevant structural underpinnings. We show that WUS exhibits a strong binding preference for TGAA repeat sequences, while retaining the ability to weakly bind to TAAT elements. This behavior is attributable to the formation of dimers through interactions of specific residues in the HD that stabilize WUS DNA interaction. Our results provide a mechanistic basis for dissecting WUS dependent regulatory networks in plant stem cell control.
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8
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Schmitt-Ney M. The FOXO's Advantages of Being a Family: Considerations on Function and Evolution. Cells 2020; 9:E787. [PMID: 32214027 PMCID: PMC7140813 DOI: 10.3390/cells9030787] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 03/16/2020] [Accepted: 03/23/2020] [Indexed: 12/12/2022] Open
Abstract
The nematode Caenorhabditis elegans possesses a unique (with various isoforms) FOXO transcription factor DAF-16, which is notorious for its role in aging and its regulation by the insulin-PI3K-AKT pathway. In humans, five genes (including a protein-coding pseudogene) encode for FOXO transcription factors that are targeted by the PI3K-AKT axis, such as in C. elegans. This common regulation and highly conserved DNA-binding domain are the pillars of this family. In this review, I will discuss the possible meaning of possessing a group of very similar proteins and how it can generate additional functionality to more complex organisms. I frame this discussion in relation to the much larger super family of Forkhead proteins to which they belong. FOXO members are very often co-expressed in the same cell type. The overlap of function and expression creates a certain redundancy that might be a safeguard against the accidental loss of FOXO function, which could otherwise lead to disease, particularly, cancer. This is one of the points that will be examined in this "family affair" report.
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Affiliation(s)
- Michel Schmitt-Ney
- Molecular Biotechnology Center, University of Torino, Via Nizza 52, 10126 Torino, Italy
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9
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Penrad-Mobayed M, Perrin C, Herman L, Todeschini AL, Nigon F, Cosson B, Caburet S, Veitia RA. Conventional and unconventional interactions of the transcription factor FOXL2 uncovered by a proteome-wide analysis. FASEB J 2019; 34:571-587. [PMID: 31914586 DOI: 10.1096/fj.201901573r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 09/11/2019] [Accepted: 10/08/2019] [Indexed: 12/19/2022]
Abstract
Beyond the study of its transcriptional target genes, the identification of the various interactors of a transcription factor (TF) is crucial to understand its diverse cellular roles. We focused on FOXL2, a winged-helix forkhead TF important for ovarian development and maintenance. FOXL2 has been implicated in diverse cellular processes, including apoptosis, the control of cell cycle or the regulation of steroid hormone synthesis. To reliably identify partners of endogenous FOXL2, we performed a proteome-wide analysis using co-immunoprecipitation in the murine granulosa cell-derived AT29c and the pituitary-derived alpha-T3 cell lines, using three antibodies targeting different parts of the protein. Following a stringent selection of mass spectrometry data on the basis of identification reliability and protein enrichment, we identified a core set of 255 partners common to both cell lines. Their analysis showed that we could co-precipitate several complexes involved in mRNA processing, chromatin remodeling and DNA replication and repair. We further validated (direct and/or indirect) interactions with selected partners, suggesting an unexpected role for FOXL2 in those processes. Overall, this comprehensive analysis of the endogenous FOXL2 interactome sheds light on its numerous and diverse interactors and unconventional cellular roles.
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Affiliation(s)
- May Penrad-Mobayed
- Institut Jacques Monod, CNRS UMR7592, Université de Paris, Paris, France
| | - Caroline Perrin
- Institut Jacques Monod, CNRS UMR7592, Université de Paris, Paris, France
| | - Laetitia Herman
- Institut Jacques Monod, CNRS UMR7592, Université de Paris, Paris, France
| | | | - Fabienne Nigon
- Epigenetics and Cell Fate, CNRS UMR7216, Université de Paris, Paris, France
| | - Bertrand Cosson
- Epigenetics and Cell Fate, CNRS UMR7216, Université de Paris, Paris, France
| | - Sandrine Caburet
- Institut Jacques Monod, CNRS UMR7592, Université de Paris, Paris, France
| | - Reiner A Veitia
- Institut Jacques Monod, CNRS UMR7592, Université de Paris, Paris, France
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10
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Wu R, Wang T, Richardson AC, Allan AC, Macknight RC, Varkonyi-Gasic E. Histone modification and activation by SOC1-like and drought stress-related transcription factors may regulate AcSVP2 expression during kiwifruit winter dormancy. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2019; 281:242-250. [PMID: 30824057 DOI: 10.1016/j.plantsci.2018.12.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 11/28/2018] [Accepted: 12/04/2018] [Indexed: 05/03/2023]
Abstract
The SHORT VEGETATIVE PHASE (SVP)-like and DORMANCY ASSOCIATED MADS-BOX (DAM) genes have been shown to regulate winter dormancy in woody perennials. In kiwifruit, AcSVP2 affects the duration of dormancy in cultivars that require high chill for dormancy release. In this study, we used a low-chill kiwifruit Actinidia chinensis 'Hort16A' to further study the function and regulation of AcSVP2. Overexpression of AcSVP2 in transgenic A. chinensis delayed budbreak in spring. A reduction in the active trimethylation histone marks of the histone H3K4 and acetylation of histone H3 contributed to the reduction of AcSVP2 expression towards dormancy release, while the inactive histone marks of trimethylation of the histone H3K27 and H3K9 in AcSVP2 locus did not show significant enrichment at the end of winter dormancy. Analysis of expression in shoot buds showed that AcSVP2 transcript was elevated in dormant buds during winter months and declined prior to budbreak, which was coordinated with expression of some of kiwifruit SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1)-like genes. Screening of 101 transcription factors in an assay with a 2.3 kb promoter region of AcSVP2 found that kiwifruit SOC1-like genes are able to activate the AcSVP2 promoter. We further identified additional transcription factors associated with drought/osmotic stress and dormancy which may regulate AcSVP2 expression.
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Affiliation(s)
- Rongmei Wu
- The New Zealand Institute for Plant & Food Research Limited (PFR) Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand
| | - Tianchi Wang
- The New Zealand Institute for Plant & Food Research Limited (PFR) Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand
| | - Annette C Richardson
- The New Zealand Institute for Plant & Food Research Limited (PFR) Kerikeri, 121 Keri Downs Road, RD1, Kerikeri 0294, New Zealand
| | - Andrew C Allan
- The New Zealand Institute for Plant & Food Research Limited (PFR) Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand; School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | - Richard C Macknight
- Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand
| | - Erika Varkonyi-Gasic
- The New Zealand Institute for Plant & Food Research Limited (PFR) Mt Albert, Private Bag 92169, Auckland Mail Centre, Auckland 1142, New Zealand.
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11
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Murawska GM, Poloni C, Simeth NA, Szymanski W, Feringa BL. Comparative Study of Photoswitchable Zinc-Finger Domain and AT-Hook Motif for Light-Controlled Peptide-DNA Binding. Chemistry 2019; 25:4965-4973. [PMID: 30735272 DOI: 10.1002/chem.201900090] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Indexed: 12/20/2022]
Abstract
DNA-peptide interactions are involved in key life processes, including DNA recognition, replication, transcription, repair, organization, and modification. Development of tools that can influence DNA-peptide binding non-invasively with high spatiotemporal precision could aid in determining its role in cells and tissues. Here, the design, synthesis, and study of photocontrolled tools for sequence-specific small peptide-DNA major and minor groove interactions are reported, shedding light on DNA binding by transcriptionally active peptides. In particular, photoswitchable moieties were implemented in the peptide backbone or turn region. In each case, DNA binding was affected by photochemical isomerization, as determined in fluorescent displacement assays on model DNA strands, which provides promising tools for DNA modulation.
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Affiliation(s)
- Gosia M Murawska
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Claudia Poloni
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Nadja A Simeth
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Wiktor Szymanski
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.,Department of Radiology, University of Groningen, University Medical Centre Groningen, Hanzeplein 1, 9713 GZ, Groningen, The Netherlands
| | - Ben L Feringa
- Centre for Systems Chemistry, Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
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12
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Novel components of germline sex determination acting downstream of foxl3 in medaka. Dev Biol 2019; 445:80-89. [DOI: 10.1016/j.ydbio.2018.10.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 10/08/2018] [Accepted: 10/23/2018] [Indexed: 12/20/2022]
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13
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Balaceanu A, Pérez A, Dans PD, Orozco M. Allosterism and signal transfer in DNA. Nucleic Acids Res 2018; 46:7554-7565. [PMID: 29905860 PMCID: PMC6125689 DOI: 10.1093/nar/gky549] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 05/11/2018] [Accepted: 06/06/2018] [Indexed: 12/14/2022] Open
Abstract
We analysed the basic mechanisms of signal transmission in DNA and the origins of the allostery exhibited by systems such as the ternary complex BAMHI-DNA-GRDBD. We found that perturbation information generated by a primary protein binding event travels as a wave to distant regions of DNA following a hopping mechanism. However, such a structural perturbation is transient and does not lead to permanent changes in the DNA geometry and interaction properties at the secondary binding site. The BAMHI-DNA-GRDBD allosteric mechanism does not occur through any traditional models: direct (protein-protein), indirect (reorganization of the secondary site) readout or solvent-release. On the contrary, it is generated by a subtle and less common entropy-mediated mechanism, which might have an important role to explain other DNA-mediated cooperative effects.
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Affiliation(s)
- Alexandra Balaceanu
- Joint IRB-BSC Program on Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
| | - Alberto Pérez
- Laufer Center for Physical and Quantitative Biology, Stony Brook University, Stony Brook, NY 11794, USA
| | - Pablo D Dans
- Joint IRB-BSC Program on Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
| | - Modesto Orozco
- Joint IRB-BSC Program on Computational Biology, Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, Spain
- Department of Biochemistry and Biomedicine, University of Barcelona, 08028 Barcelona, Spain
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14
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Quintero-Ronderos P, Laissue P. The multisystemic functions of FOXD1 in development and disease. J Mol Med (Berl) 2018; 96:725-739. [PMID: 29959475 DOI: 10.1007/s00109-018-1665-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Revised: 06/18/2018] [Accepted: 06/21/2018] [Indexed: 12/13/2022]
Abstract
Transcription factors (TFs) participate in a wide range of cellular processes due to their inherent function as essential regulatory proteins. Their dysfunction has been linked to numerous human diseases. The forkhead box (FOX) family of TFs belongs to the "winged helix" superfamily, consisting of proteins sharing a related winged helix-turn-helix DNA-binding motif. FOX genes have been extensively present during vertebrates and invertebrates' evolution, participating in numerous molecular cascades and biological functions, such as embryonic development and organogenesis, cell cycle regulation, metabolism control, stem cell niche maintenance, signal transduction, and many others. FOXD1, a forkhead TF, has been related to different key biological processes such as kidney and retina development and embryo implantation. FOXD1 dysfunction has been linked to different pathologies, thereby constituting a diagnostic biomarker and a promising target for future therapies. This paper aims to present, for the first time, a comprehensive review of FOXD1's role in mouse development and human disease. Molecular, structural, and functional aspects of FOXD1 are presented in light of physiological and pathogenic conditions, including its role in human disease aetiology, such as cancer and recurrent pregnancy loss. Taken together, the information given here should enable a better understanding of FOXD1 function for basic science researchers and clinicians.
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Affiliation(s)
- Paula Quintero-Ronderos
- Center For Research in Genetics and Genomics-CIGGUR, GENIUROS Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63C-69, Bogotá, Colombia
| | - Paul Laissue
- Center For Research in Genetics and Genomics-CIGGUR, GENIUROS Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63C-69, Bogotá, Colombia.
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15
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Theißen G, Melzer R, Rümpler F. MADS-domain transcription factors and the floral quartet model of flower development: linking plant development and evolution. Development 2017; 143:3259-71. [PMID: 27624831 DOI: 10.1242/dev.134080] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The floral quartet model of floral organ specification poses that different tetramers of MIKC-type MADS-domain transcription factors control gene expression and hence the identity of floral organs during development. Here, we provide a brief history of the floral quartet model and review several lines of recent evidence that support the model. We also describe how the model has been used in contemporary developmental and evolutionary biology to shed light on enigmatic topics such as the origin of land and flowering plants. Finally, we suggest a novel hypothesis describing how floral quartet-like complexes may interact with chromatin during target gene activation and repression.
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Affiliation(s)
- Günter Theißen
- Department of Genetics, Friedrich Schiller University Jena, 07743 Jena, Germany
| | - Rainer Melzer
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Florian Rümpler
- Department of Genetics, Friedrich Schiller University Jena, 07743 Jena, Germany
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16
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Liu X, Jiang C, Yang P. Association of single nucleotide polymorphisms in the 5' upstream region of the C4BPA gene with essential hypertension in a northeastern Han Chinese population. Mol Med Rep 2017. [PMID: 28627632 PMCID: PMC5561803 DOI: 10.3892/mmr.2017.6736] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
A previous study of the authors using microarray analysis indicated that the expression of complement component 4 binding protein (C4BP)A is upregulated in essential hypertension (EH) patients, but the association between C4BPA variations and EH has not yet been clearly demonstrated. Since the 5′ upstream region is known to serve important roles in the gene expression regulation, the present study aimed to identify and analyze the association of single nucleotide polymorphisms (SNPs) in the 5′ upstream region between the C4BPA gene with EH in a case-control study among a northeastern Han Chinese population through direct sequencing as well as genotype detection. A total of 822 unrelated participants were included. The higher expression level of C4BPA in the peripheral blood of patients with EH was verified through reverse transcription-quantitative polymerase chain reaction and ELISA. A total of four SNPs, rs73079108, rs74148971, rs77660718 and rs11120211 were identified in the 5′ upstream region of C4BPA. Association analysis demonstrated that the genotypic frequencies of rs73079108 were significantly different between EH and the control groups (P=0.011), and A allelic frequency was lower in EH (P<0.001). Logistic regression analysis indicated that the rs73079108 polymorphism was closely associated with EH (AA:GA:GG genetic model: P=0.007, odds ratio (OR)=0.604, 95% confidence interval (CI) [0.418–0.873]; AA+GA:GG genetic model: P=0.005, OR=0.806, 95% CI[0.382–0.841]), and the A allele may be a protective factor. Subgroup analysis by sex and BMI presented concordant conclusions in female and non-obese samples. Further analysis indicated that rs73079108 was associated with systolic blood pressure (P<0.001), diastolic blood pressure (P=0.001) and fast blood glucose (FBG) (P=0.021). In addition, rs73079108 GA and GG carriers reported a significant increase in the level of the protein encoded by C4BPA than those of AA carriers. The rs73079108 polymorphism in the 5′ upstream region of C4BPA was associated with EH, and rs73079108-A may be an independent predictor.
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Affiliation(s)
- Xueyan Liu
- Department of Cardiology, China‑Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
| | - Chao Jiang
- Department of Hepatobiliary Pancreatic Surgery, First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China
| | - Ping Yang
- Department of Cardiology, China‑Japan Union Hospital of Jilin University, Changchun, Jilin 130033, P.R. China
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17
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Rimpelä JM, Kontula KK, Fyhrquist F, Donner KM, Tuiskula AM, Sarin AP, Mohney RP, Stirdivant SM, Hiltunen TP. Replicated evidence for aminoacylase 3 and nephrin gene variations to predict antihypertensive drug responses. Pharmacogenomics 2017; 18:445-458. [DOI: 10.2217/pgs-2016-0204] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Aim: To replicate the genome-wide associations of the antihypertensive effects of bisoprolol and losartan in GENRES, using the Finnish patients of LIFE study. Patients & methods: We analyzed association of four SNPs with atenolol and three SNPs with losartan response in 927 Finnish LIFE patients (467 for atenolol and 460 for losartan). Results: rs2514036, a variation at a transcription start site of ACY3, was associated with blood pressure response to atenolol in men in LIFE. Response to bisoprolol was correlated to baseline plasma levels of N-acetylphenylalanine and phenylalanine (ACY3 substrate and end product, respectively) in GENRES study. NPHS1 variation rs3814995 was associated with losartan effect in LIFE. Conclusion: We provide support for two pharmacogenomic markers for beta-blockers and angiotensin receptor antagonists.
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Affiliation(s)
- Jenni M Rimpelä
- Department of Medicine, University of Helsinki, Finland
- Helsinki University Hospital, Helsinki, Finland
| | - Kimmo K Kontula
- Department of Medicine, University of Helsinki, Finland
- Helsinki University Hospital, Helsinki, Finland
| | - Frej Fyhrquist
- Minerva Foundation Institute for Medical Research, Helsinki, Finland
| | - Kati M Donner
- Institute for Molecular Medicine Finland, University of Helsinki, Finland
| | | | - Antti-Pekka Sarin
- Institute for Molecular Medicine Finland, University of Helsinki, Finland
| | | | | | - Timo P Hiltunen
- Department of Medicine, University of Helsinki, Finland
- Helsinki University Hospital, Helsinki, Finland
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18
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Guo Y, Gifford DK. Modular combinatorial binding among human trans-acting factors reveals direct and indirect factor binding. BMC Genomics 2017; 18:45. [PMID: 28061806 PMCID: PMC5219757 DOI: 10.1186/s12864-016-3434-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Accepted: 12/19/2016] [Indexed: 11/25/2022] Open
Abstract
Background The combinatorial binding of trans-acting factors (TFs) to the DNA is critical to the spatial and temporal specificity of gene regulation. For certain regulatory regions, more than one regulatory module (set of TFs that bind together) are combined to achieve context-specific gene regulation. However, previous approaches are limited to either pairwise TF co-association analysis or assuming that only one module is used in each regulatory region. Results We present a new computational approach that models the modular organization of TF combinatorial binding. Our method learns compact and coherent regulatory modules from in vivo binding data using a topic model. We found that the binding of 115 TFs in K562 cells can be organized into 49 interpretable modules. Furthermore, we found that tens of thousands of regulatory regions use multiple modules, a structure that cannot be observed with previous hard clustering based methods. The modules discovered recapitulate many published protein-protein physical interactions, have consistent functional annotations of chromatin states, and uncover context specific co-binding such as gene proximal binding of NFY + FOS + SP and distal binding of NFY + FOS + USF. For certain TFs, the co-binding partners of direct binding (motif present) differs from those of indirect binding (motif absent); the distinct set of co-binding partners can predict whether the TF binds directly or indirectly with up to 95% accuracy. Joint analysis across two cell types reveals both cell-type-specific and shared regulatory modules. Conclusions Our results provide comprehensive cell-type-specific combinatorial binding maps and suggest a modular organization of combinatorial binding. Electronic supplementary material The online version of this article (doi:10.1186/s12864-016-3434-3) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yuchun Guo
- MIT, Computer Science and Artificial Intelligence Laboratory, Cambridge, MA, 02139, USA
| | - David K Gifford
- MIT, Computer Science and Artificial Intelligence Laboratory, Cambridge, MA, 02139, USA.
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19
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van der Does HC, Fokkens L, Yang A, Schmidt SM, Langereis L, Lukasiewicz JM, Hughes TR, Rep M. Transcription Factors Encoded on Core and Accessory Chromosomes of Fusarium oxysporum Induce Expression of Effector Genes. PLoS Genet 2016; 12:e1006401. [PMID: 27855160 PMCID: PMC5140021 DOI: 10.1371/journal.pgen.1006401] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Accepted: 10/04/2016] [Indexed: 12/24/2022] Open
Abstract
Proteins secreted by pathogens during host colonization largely determine the outcome of pathogen-host interactions and are commonly called 'effectors'. In fungal plant pathogens, coordinated transcriptional up-regulation of effector genes is a key feature of pathogenesis and effectors are often encoded in genomic regions with distinct repeat content, histone code and rate of evolution. In the tomato pathogen Fusarium oxysporum f. sp. lycopersici (Fol), effector genes reside on one of four accessory chromosomes, known as the 'pathogenicity' chromosome, which can be exchanged between strains through horizontal transfer. The three other accessory chromosomes in the Fol reference strain may also be important for virulence towards tomato. Expression of effector genes in Fol is highly up-regulated upon infection and requires Sge1, a transcription factor encoded on the core genome. Interestingly, the pathogenicity chromosome itself contains 13 predicted transcription factor genes and for all except one, there is a homolog on the core genome. We determined DNA binding specificity for nine transcription factors using oligonucleotide arrays. The binding sites for homologous transcription factors were highly similar, suggesting that extensive neofunctionalization of DNA binding specificity has not occurred. Several DNA binding sites are enriched on accessory chromosomes, and expression of FTF1, its core homolog FTF2 and SGE1 from a constitutive promoter can induce expression of effector genes. The DNA binding sites of only these three transcription factors are enriched among genes up-regulated during infection. We further show that Ftf1, Ftf2 and Sge1 can activate transcription from their binding sites in yeast. RNAseq analysis revealed that in strains with constitutive expression of FTF1, FTF2 or SGE1, expression of a similar set of plant-responsive genes on the pathogenicity chromosome is induced, including most effector genes. We conclude that the Fol pathogenicity chromosome may be partially transcriptionally autonomous, but there are also extensive transcriptional connections between core and accessory chromosomes.
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Affiliation(s)
| | - Like Fokkens
- Molecular Plant Pathology, University of Amsterdam, The Netherlands
| | - Ally Yang
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON, Canada
| | - Sarah M. Schmidt
- Molecular Plant Pathology, University of Amsterdam, The Netherlands
| | - Léon Langereis
- Molecular Plant Pathology, University of Amsterdam, The Netherlands
| | | | - Timothy R. Hughes
- Banting and Best Department of Medical Research, University of Toronto, Toronto, ON, Canada
| | - Martijn Rep
- Molecular Plant Pathology, University of Amsterdam, The Netherlands
- * E-mail:
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20
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Transcription factor HIF1A: downstream targets, associated pathways, polymorphic hypoxia response element (HRE) sites, and initiative for standardization of reporting in scientific literature. Tumour Biol 2016; 37:14851-14861. [PMID: 27644243 DOI: 10.1007/s13277-016-5331-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 09/06/2016] [Indexed: 02/06/2023] Open
Abstract
Hypoxia-inducible factor-1α (HIF-1α) has crucial role in adapting cells to hypoxia through expression regulation of many genes. Identification of HIF-1α target genes (HIF-1α-TGs) is important for understanding the adapting mechanism. The aim of the present study was to collect known HIF-1α-TGs and identify their associated pathways. Targets and associated genomics data were retrieved using PubMed, WoS ( http://apps.webofknowledge.com/ ), HGNC ( http://www.genenames.org/ ), NCBI ( http://www.ncbi.nlm.nih.gov/ ), Ensemblv.84 ( http://www.ensembl.org/index.html ), DAVID Bioinformatics Resources ( https://david.ncifcrf.gov /), and Disease Ontology database ( http://disease-ontology.org/ ). From 51 papers, we collected 98 HIF-1α TGs found to be associated with 20 pathways, including metabolism of carbohydrates and pathways in cancer. Reanalysis of genomic coordinates of published HREs (hypoxia response elements) revealed six polymorphisms within HRE sites (HRE-SNPs): ABCG2, ACE, CA9, and CP. Due to large heterogeneity of results presentation in scientific literature, we also propose a first step towards reporting standardization of HIF-1α-target interactions consisting of ten relevant data types. Suggested minimal checklist for reporting will enable faster development of a complete catalog of HIF-1α-TGs, data sharing, bioinformatics analyses, and setting novel more targeted hypotheses. The proposed format for data standardization is not yet complete but presents a baseline for further optimization of the protocol with additional details, for example, regarding the experimental validation.
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21
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Bertho S, Pasquier J, Pan Q, Le Trionnaire G, Bobe J, Postlethwait JH, Pailhoux E, Schartl M, Herpin A, Guiguen Y. Foxl2 and Its Relatives Are Evolutionary Conserved Players in Gonadal Sex Differentiation. Sex Dev 2016; 10:111-29. [PMID: 27441599 DOI: 10.1159/000447611] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Indexed: 11/19/2022] Open
Abstract
Foxl2 is a member of the large family of Forkhead Box (Fox) domain transcription factors. It emerged during the last 15 years as a key player in ovarian differentiation and oogenesis in vertebrates and especially mammals. This review focuses on Foxl2 genes in light of recent findings on their evolution, expression, and implication in sex differentiation in animals in general. Homologs of Foxl2 and its paralog Foxl3 are found in all metazoans, but their gene evolution is complex, with multiple gains and losses following successive whole genome duplication events in vertebrates. This review aims to decipher the evolutionary forces that drove Foxl2/3 gene specialization through sub- and neo-functionalization during evolution. Expression data in metazoans suggests that Foxl2/3 progressively acquired a role in both somatic and germ cell gonad differentiation and that a certain degree of sub-functionalization occurred after its duplication in vertebrates. This generated a scenario where Foxl2 is predominantly expressed in ovarian somatic cells and Foxl3 in male germ cells. To support this hypothesis, we provide original results showing that in the pea aphid (insects) foxl2/3 is predominantly expressed in sexual females and showing that in bovine ovaries FOXL2 is specifically expressed in granulosa cells. Overall, current results suggest that Foxl2 and Foxl3 are evolutionarily conserved players involved in somatic and germinal differentiation of gonadal sex.
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Affiliation(s)
- Sylvain Bertho
- INRA, UR1037 Fish Physiology and Genomics, Rennes, France
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22
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Anwar MA, Yesudhas D, Shah M, Choi S. Structural and conformational insights into SOX2/OCT4-bound enhancer DNA: a computational perspective. RSC Adv 2016. [DOI: 10.1039/c6ra15176k] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The roles of SOX2 and OCT4 are critical in stem cell maintenance either in the context of iPSCs generation or cancer stem cell growth; therefore, it is imperative to study their cooperative binding and SOX2/OCT4-induced DNA conformational switching.
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Affiliation(s)
- Muhammad Ayaz Anwar
- Department of Molecular Science and Technology
- Ajou University
- Suwon 443-749
- Korea
| | - Dhanusha Yesudhas
- Department of Molecular Science and Technology
- Ajou University
- Suwon 443-749
- Korea
| | - Masaud Shah
- Department of Molecular Science and Technology
- Ajou University
- Suwon 443-749
- Korea
| | - Sangdun Choi
- Department of Molecular Science and Technology
- Ajou University
- Suwon 443-749
- Korea
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23
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Maeso I, Tena JJ. Favorable genomic environments for cis-regulatory evolution: A novel theoretical framework. Semin Cell Dev Biol 2015; 57:2-10. [PMID: 26673387 DOI: 10.1016/j.semcdb.2015.12.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 12/02/2015] [Accepted: 12/05/2015] [Indexed: 12/22/2022]
Abstract
Cis-regulatory changes are arguably the primary evolutionary source of animal morphological diversity. With the recent explosion of genome-wide comparisons of the cis-regulatory content in different animal species is now possible to infer general principles underlying enhancer evolution. However, these studies have also revealed numerous discrepancies and paradoxes, suggesting that the mechanistic causes and modes of cis-regulatory evolution are still not well understood and are probably much more complex than generally appreciated. Here, we argue that the mutational mechanisms and genomic regions generating new regulatory activities must comply with the constraints imposed by the molecular properties of cis-regulatory elements (CREs) and the organizational features of long-range chromatin interactions. Accordingly, we propose a new integrative evolutionary framework for cis-regulatory evolution based on two major premises for the origin of novel enhancer activity: (i) an accessible chromatin environment and (ii) compatibility with the 3D structure and interactions of pre-existing CREs. Mechanisms and DNA sequences not fulfilling these premises, will be less likely to have a measurable impact on gene expression and as such, will have a minor contribution to the evolution of gene regulation. Finally, we discuss current comparative cis-regulatory data under the light of this new evolutionary model, and propose that the two most prominent mechanisms for the evolution of cis-regulatory changes are the overprinting of ancestral CREs and the exaptation of transposable elements.
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Affiliation(s)
- Ignacio Maeso
- Centro Andaluz de Biología del Desarrollo (CSIC/UPO/JA), Universidad Pablo de Olavide, 41013 Seville, Spain.
| | - Juan J Tena
- Centro Andaluz de Biología del Desarrollo (CSIC/UPO/JA), Universidad Pablo de Olavide, 41013 Seville, Spain.
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24
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Fagoe ND, Attwell CL, Kouwenhoven D, Verhaagen J, Mason MRJ. Overexpression of ATF3 or the combination of ATF3, c-Jun, STAT3 and Smad1 promotes regeneration of the central axon branch of sensory neurons but without synergistic effects. Hum Mol Genet 2015; 24:6788-800. [PMID: 26385639 DOI: 10.1093/hmg/ddv383] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 09/11/2015] [Indexed: 12/26/2022] Open
Abstract
Peripheral nerve injury results in the activation of a number of transcription factors (TFs) in injured neurons, some of which may be key regulators of the regeneration-associated gene (RAG) programme. Among known RAG TFs, ATF3, Smad1, STAT3 and c-Jun have all been linked to successful axonal regeneration and have known functional and physical interactions. We hypothesised that TF expression would promote regeneration of the central axon branch of DRG neurons in the absence of a peripheral nerve lesion and that simultaneous overexpression of multiple RAG TFs would lead to greater effects than delivery of a single TF. Using adeno-associated viral vectors, we overexpressed either the combination of ATF3, Smad1, STAT3 and c-Jun with farnesylated GFP (fGFP), ATF3 only with fGFP, or fGFP only, in DRG neurons and assessed axonal regeneration after dorsal root transection or dorsal column injury and functional improvement after dorsal root injury. ATF3 alone and the combination of TFs promoted faster regeneration in the injured dorsal root. Surprisingly, however, the combination did not perform better than ATF3 alone. Neither treatment was able to induce functional improvement on sensory tests after dorsal root injury or promote regeneration in a dorsal column injury model. The lack of synergistic effects among these factors indicates that while they do increase the speed of axon growth, there may be functional redundancy between these TFs. Because axon growth is considerably less than that seen after a conditioning lesion, it appears these TFs do not induce the full regeneration programme.
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Affiliation(s)
- Nitish D Fagoe
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Callan L Attwell
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Dorette Kouwenhoven
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
| | - Joost Verhaagen
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and Center for Neurogenomics and Cognitive Research, Neuroscience Campus Amsterdam, VU University, De Boelelaan 1085, Amsterdam 1081HV, The Netherlands
| | - Matthew R J Mason
- Laboratory for Neuroregeneration, Netherlands Institute for Neuroscience, an Institute of the Royal Academy of Arts and Sciences, Meibergdreef 47, Amsterdam 1105BA, The Netherlands and
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25
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Merino F, Bouvier B, Cojocaru V. Cooperative DNA Recognition Modulated by an Interplay between Protein-Protein Interactions and DNA-Mediated Allostery. PLoS Comput Biol 2015; 11:e1004287. [PMID: 26067358 PMCID: PMC4465831 DOI: 10.1371/journal.pcbi.1004287] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 04/15/2015] [Indexed: 12/19/2022] Open
Abstract
Highly specific transcriptional regulation depends on the cooperative association of transcription factors into enhanceosomes. Usually, their DNA-binding cooperativity originates from either direct interactions or DNA-mediated allostery. Here, we performed unbiased molecular simulations followed by simulations of protein-DNA unbinding and free energy profiling to study the cooperative DNA recognition by OCT4 and SOX2, key components of enhanceosomes in pluripotent cells. We found that SOX2 influences the orientation and dynamics of the DNA-bound configuration of OCT4. In addition SOX2 modifies the unbinding free energy profiles of both DNA-binding domains of OCT4, the POU specific and POU homeodomain, despite interacting directly only with the first. Thus, we demonstrate that the OCT4-SOX2 cooperativity is modulated by an interplay between protein-protein interactions and DNA-mediated allostery. Further, we estimated the change in OCT4-DNA binding free energy due to the cooperativity with SOX2, observed a good agreement with experimental measurements, and found that SOX2 affects the relative DNA-binding strength of the two OCT4 domains. Based on these findings, we propose that available interaction partners in different biological contexts modulate the DNA exploration routes of multi-domain transcription factors such as OCT4. We consider the OCT4-SOX2 cooperativity as a paradigm of how specificity of transcriptional regulation is achieved through concerted modulation of protein-DNA recognition by different types of interactions. Pluripotent stem cells can give rise to all somatic lineages. When taken out of the context of the embryo they can be maintained and for this a core transcriptional regulatory circuitry is crucial. OCT4 and SOX2, two factors of this network, are also critical for the induction of pluripotency in somatic cells. In pluripotent cells, OCT4 and SOX2 associate on DNA regulatory regions, enhancing or modifying each other's sequence specificity. In contrast, in the early stages during induction of pluripotency, it was proposed that OCT4 explores the genome independent of SOX2. Here we report the mechanism by which SOX2 influences the orientation, dynamics, and unbinding free energy profile of OCT4. This involves an interplay of protein-protein interactions and DNA-mediated allostery. We consider that this mechanism enables OCT4 to use its DNA binding domains and the interaction partners available in a certain biological context to access alternative genome exploration routes. This study enhances the understanding of the context specific function of OCT4 and provides a general perspective on how DNA-binding cooperativity is modulated by different types of interactions.
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Affiliation(s)
- Felipe Merino
- Computational Structural Biology Group, Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany
| | - Benjamin Bouvier
- Bioinformatics: Structures and Interactions, Bases Moléculaires et Structurales des Systèmes Infectieux, Univ. Lyon I/CNRS UMR5086, IBCP, Lyon, France
| | - Vlad Cojocaru
- Computational Structural Biology Group, Department of Cell and Developmental Biology, Max Planck Institute for Molecular Biomedicine, Münster, Germany; Center for Multiscale Theory and Computation, Westfälische Wilhelms University, Münster, Germany
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26
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Abstract
UNLABELLED Upon infection, pathogen recognition leads to a rapidly activated gene expression program that induces antimicrobial effectors to clear the invader. We recently found that Nup98 regulates the expression of a subset of rapidly activated antiviral genes to restrict disparate RNA virus infections in Drosophila by promoting RNA polymerase occupancy at the promoters of these antiviral genes. How Nup98 specifically targets these loci was unclear; however, it is known that Nup98 participates with transcription factors to regulate developmental-gene activation. We reasoned that additional transcription factors may facilitate the Nup98-dependent expression of antiviral genes. In a genome-wide RNA interference (RNAi) screen, we identified a relatively understudied forkhead transcription factor, FoxK, as active against Sindbis virus (SINV) in Drosophila. Here we find that FoxK is active against the panel of viruses that are restricted by Nup98, including SINV and vesicular stomatitis virus (VSV). Mechanistically, we show that FoxK coordinately regulates the Nup98-dependent expression of antiviral genes. Depletion of FoxK significantly reduces Nup98-dependent induction of antiviral genes and reduces the expression of a forkhead response element-containing luciferase reporter. Together, these data show that FoxK-mediated activation of gene expression is Nup98 dependent. We extended our studies to mammalian cells and found that the mammalian ortholog FOXK1 is antiviral against two disparate RNA viruses, SINV and VSV, in human cells. Interestingly, FOXK1 also plays a role in the expression of antiviral genes in mammals: depletion of FOXK1 attenuates virus-inducible interferon-stimulated response element (ISRE) reporter expression. Overall, our results demonstrate a novel role for FOXK1 in regulating the expression of antiviral genes, from insects to humans. IMPORTANCE Innate immunity is characterized by rapid gene expression programs, from insects to mammals. Furthermore, we find that Nup98, known for its roles in the nuclear pore, plays a noncanonical role in binding the promoters and poising a subset of loci for rapid antiviral gene induction. It was unclear how Nup98 accesses these specific genes, and we here demonstrate that Nup98 cooperates with the transcription factor FoxK to regulate this gene expression program. Depletion of FoxK specifically reduces the induction of Nup98-dependent genes. Further, we find that the antiviral function of FoxK is conserved, as the human ortholog FOXK1 is also antiviral and regulates gene expression from virus-induced promoters. Although other forkhead transcription factors have been implicated in immunity, a role for FoxK in antiviral defense was previously unappreciated. Our findings reveal a conserved and novel role for FoxK in coordinating with Nup98 to promote a robust and complex antiviral transcriptional response.
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27
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Islam L, Kelberman D, Williamson L, Lewis N, Glindzicz MB, Nischal KK, Sowden JC. Functional Analysis of FOXE3
Mutations Causing Dominant and Recessive Ocular Anterior Segment Disease. Hum Mutat 2015; 36:296-300. [DOI: 10.1002/humu.22741] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 12/05/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Lily Islam
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
| | - Daniel Kelberman
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
| | - Laura Williamson
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
| | - Nicola Lewis
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
| | | | - Ken K. Nischal
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
- Clinical and Academic Department of Ophthalmology; Great Ormond Street Hospital for Children NHS Foundation Trust; London UK
| | - Jane C. Sowden
- Developmental Biology and Cancer; Birth Defects Research Centre; UCL Institute of Child Health; London UK
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28
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Li X, Wang W, Wang J, Malovannaya A, Xi Y, Li W, Guerra R, Hawke DH, Qin J, Chen J. Proteomic analyses reveal distinct chromatin-associated and soluble transcription factor complexes. Mol Syst Biol 2015; 11:775. [PMID: 25609649 PMCID: PMC4332150 DOI: 10.15252/msb.20145504] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The current knowledge on how transcription factors (TFs), the ultimate targets and executors of cellular signalling pathways, are regulated by protein–protein interactions remains limited. Here, we performed proteomics analyses of soluble and chromatin-associated complexes of 56 TFs, including the targets of many signalling pathways involved in development and cancer, and 37 members of the Forkhead box (FOX) TF family. Using tandem affinity purification followed by mass spectrometry (TAP/MS), we performed 214 purifications and identified 2,156 high-confident protein–protein interactions. We found that most TFs form very distinct protein complexes on and off chromatin. Using this data set, we categorized the transcription-related or unrelated regulators for general or specific TFs. Our study offers a valuable resource of protein–protein interaction networks for a large number of TFs and underscores the general principle that TFs form distinct location-specific protein complexes that are associated with the different regulation and diverse functions of these TFs.
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Affiliation(s)
- Xu Li
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Wenqi Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jiadong Wang
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Anna Malovannaya
- Department of Molecular and Cellular Biology, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Yuanxin Xi
- Department of Molecular and Cellular Biology, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA Division of Biostatistics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Wei Li
- Department of Molecular and Cellular Biology, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA Division of Biostatistics, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Rudy Guerra
- Department of Statistics, Rice University, Houston, TX, USA
| | - David H Hawke
- Proteomics Facility, Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Jun Qin
- Department of Molecular and Cellular Biology, Dan L. Duncan Cancer Center, Baylor College of Medicine, Houston, TX, USA
| | - Junjie Chen
- Department of Experimental Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Bowman CJ, Ayer DE, Dynlacht BD. Foxk proteins repress the initiation of starvation-induced atrophy and autophagy programs. Nat Cell Biol 2014; 16:1202-14. [PMID: 25402684 PMCID: PMC4250422 DOI: 10.1038/ncb3062] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Accepted: 10/13/2014] [Indexed: 12/14/2022]
Abstract
Autophagy is the primary catabolic process triggered in response to starvation. Although autophagic regulation within the cytosolic compartment is well established, it is becoming clear that nuclear events also regulate the induction or repression of autophagy. Nevertheless, a thorough understanding of the mechanisms by which sequence-specific transcription factors modulate expression of genes required for autophagy is lacking. Here, we identify Foxk proteins (Foxk1 and Foxk2) as transcriptional repressors of autophagy in muscle cells and fibroblasts. Interestingly, Foxk1/2 serve to counter-balance another forkhead transcription factor, Foxo3, which induces an overlapping set of autophagic and atrophic targets in muscle. Foxk1/2 specifically recruits Sin3A-HDAC complexes to restrict acetylation of histone H4 and expression of critical autophagy genes. Remarkably, mTOR promotes the transcriptional activity of Foxk1 by facilitating nuclear entry to specifically limit basal levels of autophagy in nutrient-rich conditions. Our study highlights an ancient, conserved mechanism whereby nutritional status is interpreted by mTOR to restrict autophagy by repressing essential autophagy genes via Foxk-Sin3-mediated transcriptional control.
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Affiliation(s)
- Christopher John Bowman
- Department of Pathology, New York University Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
| | - Donald E Ayer
- Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brian David Dynlacht
- Department of Pathology, New York University Cancer Institute, New York University School of Medicine, New York, New York 10016, USA
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Rusinova GG, Glazkova IV, Azizova TV, Osovets SV, Vyazovskaya NS. Analysis of genome instability in offspring of Mayak workers’ families: Minisatellite CEB. RUSS J GENET+ 2014. [DOI: 10.1134/s102279541411012x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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31
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Johnson EJ, Neely DM, Dunn IC, Davey MG. Direct functional consequences of ZRS enhancer mutation combine with secondary long range SHH signalling effects to cause preaxial polydactyly. Dev Biol 2014; 392:209-20. [PMID: 24907417 PMCID: PMC4111902 DOI: 10.1016/j.ydbio.2014.05.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2014] [Revised: 05/22/2014] [Accepted: 05/28/2014] [Indexed: 12/20/2022]
Abstract
Sonic hedgehog (SHH) plays a central role in patterning numerous embryonic tissues including, classically, the developing limb bud where it controls digit number and identity. This study utilises the polydactylous Silkie (Slk) chicken breed, which carries a mutation in the long range limb-specific regulatory element of SHH, the ZRS. Using allele specific SHH expression analysis combined with quantitative protein analysis, we measure allele specific changes in SHH mRNA and concentration of SHH protein over time. This confirms that the Slk ZRS enhancer mutation causes increased SHH expression in the posterior leg mesenchyme. Secondary consequences of this increased SHH signalling include increased FGF pathway signalling and growth as predicted by the SHH/GREM1/FGF feedback loop and the Growth/Morphogen models. Manipulation of Hedgehog, FGF signalling and growth demonstrate that anterior-ectopic expression of SHH and induction of preaxial polydactyly is induced secondary to increased SHH signalling and Hedgehog-dependent growth directed from the posterior limb. We predict that increased long range SHH signalling acts in combination with changes in activation of SHH transcription from the Slk ZRS allele. Through analysis of the temporal dynamics of anterior SHH induction we predict a gene regulatory network which may contribute to activation of anterior SHH expression from the Slk ZRS. Overexpression of posterior SHH in the limb bud can cause preaxial polydactyly. Increased activation of SHH/GREM/FGF feedback and growth induces Slk preaxial polydactyly. Autoregulated expression of SHH can occur within 1.5–2 h in the limb bud.
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Affiliation(s)
- Edward J Johnson
- Division of Developmental Biology, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - David M Neely
- Division of Developmental Biology, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Ian C Dunn
- Division of Genetics and Genomics, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK
| | - Megan G Davey
- Division of Developmental Biology, The Roslin Institute and R(D)SVS, University of Edinburgh, Easter Bush, Midlothian EH25 9RG, UK.
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32
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Todeschini AL, Georges A, Veitia RA. Transcription factors: specific DNA binding and specific gene regulation. Trends Genet 2014; 30:211-9. [PMID: 24774859 DOI: 10.1016/j.tig.2014.04.002] [Citation(s) in RCA: 109] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Revised: 03/26/2014] [Accepted: 04/01/2014] [Indexed: 12/15/2022]
Abstract
Specific recognition of cis-regulatory regions is essential for correct gene regulation in response to developmental and environmental signals. Such DNA sequences are recognized by transcription factors (TFs) that recruit the transcriptional machinery. Achievement of specific sequence recognition is not a trivial problem; many TFs recognize similar consensus DNA-binding sites and a genome can harbor thousands of consensus or near-consensus sequences, both functional and nonfunctional. Although genomic technologies have provided large-scale snapshots of TF binding, a full understanding of the mechanistic and quantitative details of specific recognition in the context of gene regulation is lacking. Here, we explore the various ways in which TFs recognizing similar consensus sites distinguish their own targets from a large number of other sequences to ensure specific cellular responses.
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Affiliation(s)
| | - Adrien Georges
- Institut Jacques Monod, Paris, France; Université Paris Diderot, Paris, France
| | - Reiner A Veitia
- Institut Jacques Monod, Paris, France; Université Paris Diderot, Paris, France.
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33
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Bouchoucha YX, Reingruber J, Labalette C, Wassef MA, Thierion E, Desmarquet-Trin Dinh C, Holcman D, Gilardi-Hebenstreit P, Charnay P. Dissection of a Krox20 positive feedback loop driving cell fate choices in hindbrain patterning. Mol Syst Biol 2014; 9:690. [PMID: 24061538 PMCID: PMC3792346 DOI: 10.1038/msb.2013.46] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 08/21/2013] [Indexed: 12/24/2022] Open
Abstract
A positive autoregulatory loop required for the expression of the transcription factor Krox20 was dissected using in vivo quantitative data and biophysical modelling to demonstrate how Krox20 controls cell fate decision and rhombomere size in the hindbrain. ![]()
Positive autoregulation of Krox20 underpins a bistable switch that turns a transient input signal into cell fate commitment, as demonstrated in single cell analyses. The duration and strength of the input signal control the size of the hindbrain segments by modulating the distribution between two cell fates. The progressive extinction of Krox20 expression involves a destabilization of the loop by repressor molecules.
Although feedback loops are essential in development, their molecular implementation and precise functions remain elusive. Using enhancer knockout in mice, we demonstrate that a direct, positive autoregulatory loop amplifies and maintains the expression of Krox20, a transcription factor governing vertebrate hindbrain segmentation. By combining quantitative data collected in the zebrafish with biophysical modelling that accounts for the intrinsic stochastic molecular dynamics, we dissect the loop at the molecular level. We find that it underpins a bistable switch that turns a transient input signal into cell fate commitment, as we observe in single cell analyses. The stochasticity of the activation process leads to a graded input–output response until saturation is reached. Consequently, the duration and strength of the input signal controls the size of the hindbrain segments by modulating the distribution between the two cell fates. Moreover, segment formation is buffered from severe variations in input level. Finally, the progressive extinction of Krox20 expression involves a destabilization of the loop by repressor molecules. These mechanisms are of general significance for cell type specification and tissue patterning.
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Affiliation(s)
- Yassine X Bouchoucha
- 1] Ecole Normale Supérieure, IBENS, Paris, France [2] INSERM, U1024, Paris, France [3] CNRS, UMR 8197, Paris, France
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Liu Y, Gong Z, Sun L, Li X. FOXM1 and androgen receptor co-regulate CDC6 gene transcription and DNA replication in prostate cancer cells. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:297-305. [PMID: 24583551 DOI: 10.1016/j.bbagrm.2014.02.016] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 02/19/2014] [Accepted: 02/20/2014] [Indexed: 11/18/2022]
Abstract
CDC6 is a key component of the DNA replication initiation machinery, and its transcription is regulated by E2F or androgen receptor (AR) alone or in combination in prostate cancer (PCa) cells. Through both overexpression and knockdown approaches, we found that in addition to its effects on the E2F pathway, the cell proliferation specific transcription factor FOXM1 stimulated CDC6 transcription in cooperation with AR. We have identified a forkhead box motif in the CDC6 proximal promoter that is occupied by FOXM1 and is sufficient to drive FOXM1-regulated transcription. Indirectly, FOXM1 elevated AR protein levels and AR dependent transcription. Furthermore, FOXM1 and AR proteins physically interact. Using synchronized cultures, we observed that CDC6 expression is elevated near S phase of the cell cycle, at a time coinciding with elevated FOXM1 and AR expression and CDC6 promoter occupancy by both AR and FOXM1 proteins. Androgen increased the binding of AR protein to CDC6 promoter, and AR and FOXM1 knockdown decreased AR binding. These results provided new evidence for the regulatory mechanism of aberrant CDC6 oncogene transcription by FOXM1 and AR, two highly expressed transcription factors in PCa cells. Functionally, the cooperation of FOXM1 and AR accelerated DNA synthesis and cell proliferation by affecting CDC6 gene expression. Furthermore, siomycin A, a proteasome inhibitor known to inhibit FOXM1 expression and activity, inhibited PCa cell proliferation and its effect was additive to that of bicalutamide, an antiandrogen commonly used to treat PCa patients.
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Affiliation(s)
- Youhong Liu
- Center for Molecular Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan Province 410008, People's Republic of China
| | - Zhicheng Gong
- Department of Pharmacy, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan Province 410008, People's Republic of China
| | - Lunquan Sun
- Center for Molecular Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan Province 410008, People's Republic of China
| | - Xiong Li
- Center for Molecular Medicine, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan Province 410008, People's Republic of China.
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Abstract
Much of what is known about mammalian cell regulation has been achieved with the aid of transiently transfected cells. However, overexpression can violate balanced gene dosage, affecting protein folding, complex assembly and downstream regulation. To avoid these problems, genome engineering technologies now enable the generation of stable cell lines expressing modified proteins at (almost) native levels.
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Affiliation(s)
- Toby J Gibson
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg, Germany.
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36
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Vacha P, Zuskova I, Bumba L, Herman P, Vecer J, Obsilova V, Obsil T. Detailed kinetic analysis of the interaction between the FOXO4–DNA-binding domain and DNA. Biophys Chem 2013; 184:68-78. [DOI: 10.1016/j.bpc.2013.09.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 09/05/2013] [Accepted: 09/05/2013] [Indexed: 12/01/2022]
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37
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Bost B, Veitia RA. Dominance and interloci interactions in transcriptional activation cascades: models explaining compensatory mutations and inheritance patterns. Bioessays 2013; 36:84-92. [PMID: 24242332 DOI: 10.1002/bies.201300109] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutations in human genes encoding transcription factors are often dominant because one active allele cannot ensure a normal phenotype (haploinsufficiency). In other instances, heterozygous mutations of two genes are required for a phenotype to appear (combined haploinsufficiency). Here, we explore with models (i) the basis of haploinsufficiency and combined haploinsufficiency owing to mutations in transcription activators, and (ii) how the effects of such mutations can be amplified or buffered by subsequent steps in a transcription cascade. We propose that the non-linear (sigmoidal) response of transcription to the concentration of activators can explain haploinsufficiency. We further show that the sigmoidal character of the output of a cascade increases with the number of steps involved, the settings of which will determine the buffering or enhancement of the effects of a decreased concentration of an upstream activator. This exploration provides insights into the bases of compensatory mutations and on interloci interactions underlying oligogenic inheritance patterns.
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Affiliation(s)
- Bruno Bost
- Université Paris-Sud, IGM, UMR8621, Orsay, France; CNRS, Orsay, France
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Guturu H, Doxey AC, Wenger AM, Bejerano G. Structure-aided prediction of mammalian transcription factor complexes in conserved non-coding elements. Philos Trans R Soc Lond B Biol Sci 2013; 368:20130029. [PMID: 24218641 DOI: 10.1098/rstb.2013.0029] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Mapping the DNA-binding preferences of transcription factor (TF) complexes is critical for deciphering the functions of cis-regulatory elements. Here, we developed a computational method that compares co-occurring motif spacings in conserved versus unconserved regions of the human genome to detect evolutionarily constrained binding sites of rigid TF complexes. Structural data were used to estimate TF complex physical plausibility, explore overlapping motif arrangements seldom tackled by non-structure-aware methods, and generate and analyse three-dimensional models of the predicted complexes bound to DNA. Using this approach, we predicted 422 physically realistic TF complex motifs at 18% false discovery rate, the majority of which (326, 77%) contain some sequence overlap between binding sites. The set of mostly novel complexes is enriched in known composite motifs, predictive of binding site configurations in TF-TF-DNA crystal structures, and supported by ChIP-seq datasets. Structural modelling revealed three cooperativity mechanisms: direct protein-protein interactions, potentially indirect interactions and 'through-DNA' interactions. Indeed, 38% of the predicted complexes were found to contain four or more bases in which TF pairs appear to synergize through overlapping binding to the same DNA base pairs in opposite grooves or strands. Our TF complex and associated binding site predictions are available as a web resource at http://bejerano.stanford.edu/complex.
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Affiliation(s)
- Harendra Guturu
- Department of Electrical Engineering, Stanford University, , Stanford, CA 94305, USA
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39
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Pathways by which the interplay of organismic and environmental factors lead to phenotypic variation within and across generations. ADVANCES IN CHILD DEVELOPMENT AND BEHAVIOR 2013; 44:325-54. [PMID: 23834011 DOI: 10.1016/b978-0-12-397947-6.00012-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The range of responses made to environmental exigencies by animals, including humans, may be impacted by the experiences of their progenitors. In mammals, pathways have been documented ranging from transactions between a mother and her developing fetus in the womb through continuity of parenting practices and cultural inheritance. In addition, phenotypic plasticity may be constrained by factors transmitted by the gametes that are involved in the regulation of gene expression rather than modifications to the genome itself. Possible mediators for this kind of inheritance are examined, and the conditions that might have led to the evolution of such transmission are considered. Anticipatory adjustments to possible environmental exigencies are likely to occur when such conditions recur regularly, but intermittently across generations and endure for substantial periods of time, and when adjusting to them after the fact is likely to be biologically costly, even life-threatening. It appears that physical growth and responses to nutrient availability are domains in which anticipatory, epigenetically inherited adjustments occur. In addition, given the fact that humans have oppressed one another repeatedly and for relatively long periods of time, such behavioral tendencies as boldness or innovativeness may be behavioral traits subject to such effects. The implications of these factors for research and policy are discussed.
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40
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Sullivan C, Liu Y, Shen J, Curtis A, Newman C, Hock JM, Li X. Novel interactions between FOXM1 and CDC25A regulate the cell cycle. PLoS One 2012; 7:e51277. [PMID: 23240008 PMCID: PMC3519786 DOI: 10.1371/journal.pone.0051277] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 10/31/2012] [Indexed: 01/03/2023] Open
Abstract
FOXM1 is a critical regulator of the G1/S and G2/M cell cycle transitions, as well as of the mitotic spindle assembly. Previous studies have suggested that FOXM1 regulates CDC25A gene transcription, but the mechanism remains unknown. Here, we provide evidence that FOXM1 directly regulates CDC25A gene transcription via direct promoter binding and indirect activation of E2F-dependent pathways. Prior literature reported that CDC25B and CDC25C activate CDK1/cyclinB complexes in order to enable phosphorylation of FOXM1. It was unknown if CDC25A functions in a similar manner. We report that FOXM1 transcriptional activity is synergistically enhanced when co-expressed with CDC25A. The increase is dependent upon CDK1 phosphorylation of FOXM1 at T600, T611 and T620 residues. We also report a novel protein interaction between FOXM1 and CDC25A via the C-terminus of FOXM1. We demonstrate that the phosphorylation of Thr 600 and Thr 611 residues of FOXM1 enhanced this interaction, and that the interaction is dependent upon CDC25A phosphatase activity. Our work provides novel insight into the underlying mechanisms by which FOXM1 controls the cell cycle through its association with CDC25A.
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Affiliation(s)
- Con Sullivan
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
- The University of Maine, Orono, Maine, United States of America
| | - Youhong Liu
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
- Center for Molecular Medicine, Xiangya Hospital, Central South University, Changsha, Hunan Province, People's Republic of China
| | - Jingjing Shen
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
| | - Adam Curtis
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
| | - Christina Newman
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
| | - Janet M. Hock
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
| | - Xiong Li
- Maine Institute for Human Genetics and Health, Brewer, Maine, United States of America
- Center for Molecular Medicine, Xiangya Hospital, Central South University, Changsha, Hunan Province, People's Republic of China
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41
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Goode DK, Elgar G. Capturing the regulatory interactions of eukaryote genomes. Brief Funct Genomics 2012; 12:142-60. [PMID: 23117864 DOI: 10.1093/bfgp/els041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
A key finding from early genomics research is the remarkable consistency in the number of protein-coding regions across diverse species. This has led many researchers to look to the cis-regulatory elements of genes as the fundamental influence behind evolving gene function and subsequent species diversification. Historically, since these elements are often located in vast intergenic and intronic regions of the genome, their identification has been recalcitrant. Now, with the deluge of whole-genome data from representatives of numerous eukaryotic lineages, various approaches have enabled us to begin to recognize features that characterize regulatory regions of the genome. Here we endeavour to collate these approaches in order to give an overview of the complexities involved in extrapolating regulatory signatures. The resource provided by the escalating richness of whole-genome datasets enables more sophisticated modelling of these regulatory signatures yet at the same time introduces increasing potential for noise. While we are only at the advent of making these discoveries, the next decade promises to be a very exciting and rewarding time for genome researchers.
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Affiliation(s)
- Debbie K Goode
- Cambridge Institute for Medical Research, Deptartment of Haematology, Addenbrooke's Hospital, Hills Road, Cambridge, UK
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42
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Wildenhain S, Ingenhag D, Ruckert C, Degistirici Ö, Dugas M, Meisel R, Hauer J, Borkhardt A. Homeobox protein HB9 binds to the prostaglandin E receptor 2 promoter and inhibits intracellular cAMP mobilization in leukemic cells. J Biol Chem 2012; 287:40703-12. [PMID: 23048027 DOI: 10.1074/jbc.m111.308965] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
BACKGROUND HB9 is highly expressed in translocation t(7;12) positive infant AML. RESULTS HB9 binds to the PTGER2 promoter, down-regulates PTGER2 gene expression and subsequently represses cAMP synthesis in hematopoietic cells. CONCLUSION Expression of HLXB9 represses PTGER2 mediated signaling. SIGNIFICANCE First molecular report of HB9-dependent target gene regulation in hematopoietic cells. The transcription factor HB9, encoded by the homeobox gene B9 (HLXB9), is involved in the development of pancreatic beta- and motor neuronal cells. In addition, HLXB9 is recurrently rearranged in young children with acute myeloid leukemia characterized by a chromosomal translocation t(7;12)-HLXB9/TEL and concomitant high expression of the unrearranged, wild-type HLXB9 allele. However, target genes of HB9 in hematopoietic cells are not known to date. In this study, we used ChIP-on-chip analysis together with expression profiling and identified PTGER2 (prostaglandin E receptor 2) as a target gene of HB9 in a hematopoietic cell line. The functional HB9 homeodomain as well as the HB9 binding domain within the PTGER2 promoter are essential for binding of HB9 to the PTGER2 promoter region and down-regulation of PTGER2 expression. Functionally, HB9 conducted down-regulation of PTGER2 results in a reduced content of intracellular cAMP mobilization and furthermore the decreased PTGER2 gene expression is valid in bone marrow cells from translocation t(7;12) positive patients. Among the primary and secondary target genes of HB9 in the myeloid cell line HL60, 78% of significantly regulated genes are down-regulated, indicating an overall repressive function of HB9. Differentially regulated genes were preferentially confined to pathways involved in cell-adhesion and cell-cell interactions, similar to the gene expression footprint of HLXB9-expressing cells from t(7;12) positive patients.
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Affiliation(s)
- Sarah Wildenhain
- Department of Pediatric Oncology, Hematology, and Clinical Immunology, Center for Child and Adolescent Health, Heinrich Heine University, 40225 Düsseldorf, Germany
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43
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Cooperativity of stress-responsive transcription factors in core hypoxia-inducible factor binding regions. PLoS One 2012; 7:e45708. [PMID: 23029193 PMCID: PMC3454324 DOI: 10.1371/journal.pone.0045708] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Accepted: 08/22/2012] [Indexed: 11/19/2022] Open
Abstract
The transcriptional response driven by Hypoxia-inducible factor (HIF) is central to the adaptation to oxygen restriction. Despite recent characterization of genome-wide HIF DNA binding locations and hypoxia-regulated transcripts in different cell types, the molecular bases of HIF target selection remain unresolved. Herein, we combined multi-level experimental data and computational predictions to identify sequence motifs that may contribute to HIF target selectivity. We obtained a core set of bona fide HIF binding regions by integrating multiple HIF1 DNA binding and hypoxia expression profiling datasets. This core set exhibits evolutionarily conserved binding regions and is enriched in functional responses to hypoxia. Computational prediction of enriched transcription factor binding sites identified sequence motifs corresponding to several stress-responsive transcription factors, such as activator protein 1 (AP1), cAMP response element-binding (CREB), or CCAAT-enhancer binding protein (CEBP). Experimental validations on HIF-regulated promoters suggest a functional role of the identified motifs in modulating HIF-mediated transcription. Accordingly, transcriptional targets of these factors are over-represented in a sorted list of hypoxia-regulated genes. Altogether, our results implicate cooperativity among stress-responsive transcription factors in fine-tuning the HIF transcriptional response.
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44
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Lelli KM, Slattery M, Mann RS. Disentangling the many layers of eukaryotic transcriptional regulation. Annu Rev Genet 2012; 46:43-68. [PMID: 22934649 DOI: 10.1146/annurev-genet-110711-155437] [Citation(s) in RCA: 159] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Regulation of gene expression in eukaryotes is an extremely complex process. In this review, we break down several critical steps, emphasizing new data and techniques that have expanded current gene regulatory models. We begin at the level of DNA sequence where cis-regulatory modules (CRMs) provide important regulatory information in the form of transcription factor (TF) binding sites. In this respect, CRMs function as instructional platforms for the assembly of gene regulatory complexes. We discuss multiple mechanisms controlling complex assembly, including cooperative DNA binding, combinatorial codes, and CRM architecture. The second section of this review places CRM assembly in the context of nucleosomes and condensed chromatin. We discuss how DNA accessibility and histone modifications contribute to TF function. Lastly, new advances in chromosomal mapping techniques have provided increased understanding of intra- and interchromosomal interactions. We discuss how these topological maps influence gene regulatory models.
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Affiliation(s)
- Katherine M Lelli
- Department of Genetics and Development, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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45
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Garcia-Bassets I, Wang D. Cistrome plasticity and mechanisms of cistrome reprogramming. Cell Cycle 2012; 11:3199-210. [PMID: 22895178 DOI: 10.4161/cc.21281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mammalian genomes contain thousands of cis-regulatory elements for each transcription factor (TF), but TFs only occupy a relatively small subset referred to as cistrome. Recent studies demonstrate that a TF cistrome might differ among different organisms, tissue types and individuals. In a cell, a TF cistrome might differ among different physiological states, pathological stages and between physiological and pathological conditions. It is, therefore, remarkable how highly plastic these binding profiles are, and how massively they can be reprogrammed in rapid response to intra/extracellular variations and during cell identity transitions and evolution. Biologically, cistrome reprogramming events tend to be followed by changes in transcriptional outputs, thus serving as transformative mechanisms to synchronically alter the biology of the cell. In this review, we discuss the molecular basis of cistrome plasticity and attempt to integrate the different mechanisms and biological conditions associated with cistrome reprogramming. Emerging data suggest that, when altered, these reprogramming events might be linked to tumor development and/or progression, which is a radical conceptual change in our mechanistic understanding of cancer and, potentially, other diseases.
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Affiliation(s)
- Ivan Garcia-Bassets
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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L'Hôte D, Georges A, Todeschini AL, Kim JH, Benayoun BA, Bae J, Veitia RA. Discovery of novel protein partners of the transcription factor FOXL2 provides insights into its physiopathological roles. Hum Mol Genet 2012; 21:3264-74. [PMID: 22544055 DOI: 10.1093/hmg/dds170] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
FOXL2 transcription factor is responsible for the Blepharophimosis Ptosis Epicantus inversus Syndrome (BPES), a genetic disease involving craniofacial malformations often associated with ovarian failure. Recently, a somatic FOXL2 mutation (p.C134W) has been reported in >95% of adult-type granulosa cell tumors. Here, we have identified 10 novel FOXL2 partners by yeast-two-hybrid screening and co-immunoprecipitation. Most BPES-inducing mutated FOXL2 proteins display aggregation in cultured cells. Here, we show that two of the partners (NR2C1 and GMEB1) can be sequestered in such aggregates. This co-aggregation can contribute to the pathogenesis of FOXL2 mutations. We have also measured the effects of FOXL2 interactants on the transcriptional regulation of a series of target promoters. Some of the partners (CXXC4, CXXC5, BANF1) were able to repress FOXL2 activity indistinctively of the promoter. Interestingly, CREM-τ2α, which acted as a repressor on most promoters, increased wild-type (WT) FOXL2 activity on two promoters (PTGS2 and CYP19A1), but was unable to increase the activity of the oncogenic mutant p.C134W. Conversely, GMEB1, which also acted as a repressor on most promoters and increased WT FOXL2 activity on the Per2 promoter, increased to a greater extent the activity of the p.C134W variant. Interestingly, partners with intrinsic pro-apoptotic effect were able to increase apoptosis induction by WT FOXL2, but not by the p.C134W mutant, whereas partners with an anti-apoptotic effect decreased apoptosis induction by both FOXL2 versions. Altogether, these results suggest that the p.C134W mutated form fails to integrate signals through protein-protein interactions to regulate target promoter subsets and in particular to induce cell death.
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Affiliation(s)
- David L'Hôte
- Institut Jacques Monod, UMR 7592 CNRS-Université Paris Diderot, Paris 75205, France
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Baumann M, Höppner MP, Meier M, Pontiller J, Ernst W, Grabherr R, Mauceli E, Grabherr MG. Artificially designed promoters: understanding the role of spatial features and canonical binding sites in transcription. Bioeng Bugs 2012; 3:120-3. [PMID: 22095054 DOI: 10.4161/bbug.18530] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The promoter is a key element in gene transcription and regulation. We previously reported that artificial sequences rich in the dinucleotide CpG are sufficient to drive expression in vitro in mammalian cell lines, without requiring canonical binding sites for transcription factor proteins. Here, we report that introducing a promoter organization that alternates in CpGs and regions rich in A and T further increases expression strength, as well as how insertion of specific binding sites makes such sequences respond to induced levels of the transcription factor NFκB. Our findings further contribute to the mechanistic understanding of promoters, as well as how these sequences might be shaped by evolutionary pressure in living organisms.
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Affiliation(s)
- Martina Baumann
- Department of Biotechnology; University of Natural Resources and Applied Life Sciences, Vienna, Austria
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Transcriptional regulation in Saccharomyces cerevisiae: transcription factor regulation and function, mechanisms of initiation, and roles of activators and coactivators. Genetics 2012; 189:705-36. [PMID: 22084422 DOI: 10.1534/genetics.111.127019] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Here we review recent advances in understanding the regulation of mRNA synthesis in Saccharomyces cerevisiae. Many fundamental gene regulatory mechanisms have been conserved in all eukaryotes, and budding yeast has been at the forefront in the discovery and dissection of these conserved mechanisms. Topics covered include upstream activation sequence and promoter structure, transcription factor classification, and examples of regulated transcription factor activity. We also examine advances in understanding the RNA polymerase II transcription machinery, conserved coactivator complexes, transcription activation domains, and the cooperation of these factors in gene regulatory mechanisms.
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Tanaka T, Padavattan S, Kumarevel T. Crystal structure of archaeal chromatin protein Alba2-double-stranded DNA complex from Aeropyrum pernix K1. J Biol Chem 2012; 287:10394-10402. [PMID: 22334696 DOI: 10.1074/jbc.m112.343210] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
All thermophilic and hyperthermophilic archaea encode homologs of dimeric Alba (Sac10b) proteins that bind cooperatively at high density to DNA. Here, we report the 2.0 Å resolution crystal structure of an Alba2 (Ape10b2)-dsDNA complex from Aeropyrum pernix K1. A rectangular tube-like structure encompassing duplex DNA reveals the positively charged residues in the monomer-monomer interface of each dimer packing on either side of the bound dsDNA in successive minor grooves. The extended hairpin loop connecting strands β3 and β4 undergoes significant conformational changes upon DNA binding to accommodate the other Alba2 dimer during oligomerization. Mutational analysis of key interacting residues confirmed the specificity of Alba2-dsDNA interactions.
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Affiliation(s)
- Tomoyuki Tanaka
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
| | - Sivaraman Padavattan
- RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan
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Scherrer K. Regulation of gene expression and the transcription factor cycle hypothesis. Biochimie 2012; 94:1057-68. [PMID: 22234303 DOI: 10.1016/j.biochi.2011.12.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 12/09/2011] [Indexed: 11/26/2022]
Abstract
Post-genomic data show unexpected extent of the transcribed genome and the size of individual primary transcripts. Hence, most cis-regulatory modules (CRMs) binding transcription factors (TFs) at promotor, enhancer and other sites are actually transcribed within full domain transcripts (FDTs). The ensemble of these CRMs placed way upstream of exon clusters, downstream and in intronic or intergenic positions represent a program of gene expression which has been formally analysed within the Gene and Genon concept [1,2]. This concept has emphasised the necessity to separate product information from regulative information to allow information-theoretic analysis of gene expression. Classically, TFs have been assumed to act at DNA level exclusively but evidence has accumulated indicating eventual post-transcriptional functions. The transcription factor cycle (TFC) hypothesis suggests the transfer of DNA-bound factors to nascent RNA. Exerting downstream functions in RNA processing and transport, these factors would be liberated by RNA processing and cycle back to the DNA maintaining active transcription. Sequestered on RNA in absence of processing they would constitute a negative feedback loop. The TFC concept may explain epigenetic regulation in mitosis and meiosis. In mitosis control factors may survive as single proteins but also attached to FDTs as organised complexes. This process might perpetuate in cell division conditioning of chromatin for transcription. As observed on lampbrush chromosomes formed in avian and amphibian oogenesis, in meiosis the genome is fully transcribed and oocytes conserve high Mr RNA of high sequence complexity. When new interphase chromosomes form in daughter cells and early embryogenesis, TFs and other factors attached to RNA might be reinserted onto the DNA.
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Affiliation(s)
- Klaus Scherrer
- Inst. J. Monod, CNRS and University Paris Diderot, 9, rue Larrey, 75005 Paris, France
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