1
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Peng T, Du SY, Son M, Diamond B. HIF-1α is a negative regulator of interferon regulatory factors: Implications for interferon production by hypoxic monocytes. Proc Natl Acad Sci U S A 2021; 118:e2106017118. [PMID: 34108245 PMCID: PMC8256008 DOI: 10.1073/pnas.2106017118] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Patients with severe COVID-19 infection exhibit a low level of oxygen in affected tissue and blood. To understand the pathophysiology of COVID-19 infection, it is therefore necessary to understand cell function during hypoxia. We investigated aspects of human monocyte activation under hypoxic conditions. HMGB1 is an alarmin released by stressed cells. Under normoxic conditions, HMGB1 activates interferon regulatory factor (IRF)5 and nuclear factor-κB in monocytes, leading to expression of type I interferon (IFN) and inflammatory cytokines including tumor necrosis factor α, and interleukin 1β, respectively. When hypoxic monocytes are activated by HMGB1, they produce proinflammatory cytokines but fail to produce type I IFN. Hypoxia-inducible factor-1α, induced by hypoxia, functions as a direct transcriptional repressor of IRF5 and IRF3. As hypoxia is a stressor that induces secretion of HMGB1 by epithelial cells, hypoxia establishes a microenvironment that favors monocyte production of inflammatory cytokines but not IFN. These findings have implications for the pathogenesis of COVID-19.
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Affiliation(s)
- Travis Peng
- Center for Autoimmune Musculoskeletal and Hematopoietic Diseases, Feinstein Institutes for Medical Research, Manhasset, NY 11030
| | - Shin-Yi Du
- Center for Autoimmune Musculoskeletal and Hematopoietic Diseases, Feinstein Institutes for Medical Research, Manhasset, NY 11030
| | - Myoungsun Son
- Center for Autoimmune Musculoskeletal and Hematopoietic Diseases, Feinstein Institutes for Medical Research, Manhasset, NY 11030;
- Department of Molecular Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549
| | - Betty Diamond
- Center for Autoimmune Musculoskeletal and Hematopoietic Diseases, Feinstein Institutes for Medical Research, Manhasset, NY 11030
- Department of Molecular Medicine, Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, Hempstead, NY 11549
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2
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Roy S, Guha Roy D, Bhushan A, Bharatiya S, Chinnaswamy S. Functional genetic variants of the IFN-λ3 (IL28B) gene and transcription factor interactions on its promoter. Cytokine 2021; 142:155491. [PMID: 33725487 PMCID: PMC7611124 DOI: 10.1016/j.cyto.2021.155491] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/26/2021] [Accepted: 03/01/2021] [Indexed: 12/27/2022]
Abstract
Interferon lambda 3 (IFN-λ3 or IFNL3, formerly IL28B), a type III interferon, modulates immune responses during infection/inflammation. Several human studies have reported an association of single nucleotide polymorphisms (SNP) in the IFNL3 locus with expression level of IFNL3. Previous genetic studies, in the context of hepatitis C virus infections, had predicted three regulatory SNPs: rs4803219, rs28416813 and rs4803217 that could have functional/causal roles. Subsequent studies confirmed this prediction for rs28416813 and rs4803217. A dinucleotide TA-repeat variant (rs72258881) has also been reported to be regulating the IFN-λ3 promoter. In this study, we tested all these genetic variants using a sensitive reporter assay. We show that the minor/ancestral alleles of both rs28416813 and rs4803217, together have a strong inhibitory effect on reporter gene expression. We also show an interaction between the two principal transcription factors regulating IFNL3 promoter: IRF7 and NF-kB RelA/p65. We show that IRF7 and p65 physically interact with each other. By using a transient ChIP assay, we show that presence of p65 increases the promoter occupancy of IRF7, thereby leading to synergistic activation of the IFNL3 promoter. We reason that, in contrast to p65, a unique nature of IRF7 binding to its specific DNA sequence makes it more sensitive to changes in DNA phasing. As a result, we see that IRF7, but not p65-mediated transcriptional activity is affected by the phase changes introduced by the TA-repeat polymorphism. Overall, we see that three genetic variants: rs28416813, rs4803217 and rs72258881 could have functional roles in controlling IFNL3 gene expression.
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Affiliation(s)
- Subhajit Roy
- National Institute of Biomedical Genomics, P.O.:N.S.S., Kalyani, West Bengal 741251, India
| | - Debarati Guha Roy
- National Institute of Biomedical Genomics, P.O.:N.S.S., Kalyani, West Bengal 741251, India
| | - Anand Bhushan
- National Institute of Biomedical Genomics, P.O.:N.S.S., Kalyani, West Bengal 741251, India
| | - Seema Bharatiya
- National Institute of Biomedical Genomics, P.O.:N.S.S., Kalyani, West Bengal 741251, India
| | - Sreedhar Chinnaswamy
- National Institute of Biomedical Genomics, P.O.:N.S.S., Kalyani, West Bengal 741251, India.
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3
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Ötvös K, Miskolczi P, Marhavý P, Cruz-Ramírez A, Benková E, Robert S, Bakó L. Pickle Recruits Retinoblastoma Related 1 to Control Lateral Root Formation in Arabidopsis. Int J Mol Sci 2021; 22:ijms22083862. [PMID: 33917959 PMCID: PMC8068362 DOI: 10.3390/ijms22083862] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 04/04/2021] [Accepted: 04/06/2021] [Indexed: 12/31/2022] Open
Abstract
Lateral root (LR) formation is an example of a plant post-embryonic organogenesis event. LRs are issued from non-dividing cells entering consecutive steps of formative divisions, proliferation and elongation. The chromatin remodeling protein PICKLE (PKL) negatively regulates auxin-mediated LR formation through a mechanism that is not yet known. Here we show that PKL interacts with RETINOBLASTOMA-RELATED 1 (RBR1) to repress the LATERAL ORGAN BOUNDARIES-DOMAIN 16 (LBD16) promoter activity. Since LBD16 function is required for the formative division of LR founder cells, repression mediated by the PKL–RBR1 complex negatively regulates formative division and LR formation. Inhibition of LR formation by PKL–RBR1 is counteracted by auxin, indicating that, in addition to auxin-mediated transcriptional responses, the fine-tuned process of LR formation is also controlled at the chromatin level in an auxin-signaling dependent manner.
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Affiliation(s)
- Krisztina Ötvös
- Department of Plant Physiology, Umeå Plant Science Center, Umeå University, S-901 87 Umeå, Sweden
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria; (P.M.); (E.B.)
- Bioresources Unit, AIT Austrian Institute of Technology, 3430 Tulln, Austria
- Correspondence: (K.Ö.); (L.B.); Tel.: +46-907867970 (K.Ö.); Fax: +46-907866676 (K.Ö.)
| | - Pál Miskolczi
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, S-901 87 Umeå, Sweden; (P.M.); (S.R.)
| | - Peter Marhavý
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria; (P.M.); (E.B.)
| | - Alfredo Cruz-Ramírez
- Laboratory of Molecular and Developmental Complexity at Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, (CINVESTAV-IPN), 36590 Irapuato, Mexico;
| | - Eva Benková
- Institute of Science and Technology Austria, Am Campus 1, 3400 Klosterneuburg, Austria; (P.M.); (E.B.)
| | - Stéphanie Robert
- Department of Forest Genetics and Plant Physiology, Umeå Plant Science Center, Swedish University of Agricultural Sciences, S-901 87 Umeå, Sweden; (P.M.); (S.R.)
| | - László Bakó
- Department of Plant Physiology, Umeå Plant Science Center, Umeå University, S-901 87 Umeå, Sweden
- Correspondence: (K.Ö.); (L.B.); Tel.: +46-907867970 (K.Ö.); Fax: +46-907866676 (K.Ö.)
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Sengupta P, Bhattacharya A, Sa G, Das T, Chatterjee S. Truncated G-Quadruplex Isomers Cross-Talk with the Transcription Factors To Maintain Homeostatic Equilibria in c-MYC Transcription. Biochemistry 2019; 58:1975-1991. [PMID: 30920805 DOI: 10.1021/acs.biochem.9b00030] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The nuclease hypersensitive element III1 (NHE III1) upstream c-MYC promoter harbors a transcription-silencing G-quadruplex (Pu27) element. Dynamic turnover of various transcription factors (TFs) across Pu27 to control c-MYC transcription homeostasis is enigmatic. Here, we reveal that native Pu27 evolves truncated G-quadruplex isomers (Pu19, Pu22, Pu24, and Pu25) in cells that are optimal intracellular targets of specific TFs in a sequence- and structure-dependent manner. Nuclear magnetic resonance and isothermal titration calorimetry envisaged that NM23-H2 (nucleoside diphosphate kinase) and nucleolin induce conformational fluctuations in Pu27 to sample specific conformationally restricted conformer(s). Structural investigations revealed that the flanking guanines at 5'-Pu27 control solvent exposure at G-quartets upon NM23-H2 and nucleolin binding driving Pu27 unfolding and folding, respectively. Transient chromatin immunoprecipitations confirmed that NM23-H2 drives the conformation switch to Pu24 that outcompetes nucleolin recruitment. Similarly, nucleolin arrests Pu27 in the Pu22 conformer minimizing NM23-H2 binding at Pu27. hnRNPK (heterogeneous nuclear ribonucleoprotein K) positively regulates NM23-H2 and nucleolin association at Pu27 despite their antagonism. On the basis of these results, we simulated the transcription kinetics in a feed-forward loop in which the transcription output responds to hnRNPK-induced early activation via NM23-H2 association, which favors Pu24 formation at NHE III1 reducing nucleolin occupancy and driving quadruplex unfolding to initiate transcription. NM23-H2 further promotes hnRNPK deposition across NHE III1 altering Pu27 plasticity that finally enriches the nucleolin abundance to drive Pu22 formation and weaken NM23-H2 binding to extinguish transcription. This mechanism involves three positive feedback loops (NM23-H2-hnRNPK, NM23-H2-CNBP, and hnRNPK-nucleolin) and one negative feedback loop (NM23-H2-nucleolin) controlling optimal turnover and residence time of TFs at Pu27 to homeostatically regulate c-MYC transcription.
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Affiliation(s)
- Pallabi Sengupta
- Department of Biophysics , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Apoorva Bhattacharya
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Gaurisankar Sa
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Tanya Das
- Division of Molecular Medicine , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
| | - Subhrangsu Chatterjee
- Department of Biophysics , Bose Institute , P 1/12, C. I. T. Road, Scheme-VIIM , Kolkata 700054 , West Bengal , India
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5
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A methyl-sensitive element induces bidirectional transcription in TATA-less CpG island-associated promoters. PLoS One 2018; 13:e0205608. [PMID: 30332484 PMCID: PMC6192621 DOI: 10.1371/journal.pone.0205608] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Accepted: 09/27/2018] [Indexed: 12/21/2022] Open
Abstract
How TATA-less promoters such as those within CpG islands (CGI) control gene expression is still a subject of active research. Here, we have identified the "CGCG element", a ten-base pair motif with a consensus sequence of TCTCGCGAGA present in a group of promoter-associated CGI-enriched in ribosomal protein and housekeeping genes. This element is evolutionarily conserved in vertebrates, found in DNase-accessible regions and employs RNA Pol II to activate gene expression. Through analysis of capped-nascent transcripts and supporting evidence from reporter assays, we demonstrate that this element activates bidirectional transcription through divergent start sites. Methylation of this element abrogates the associated promoter activity. When coincident with a TATA-box, directional transcription remains CGCG-dependent. Because the CGCG element is sufficient to drive transcription, we propose that its unmethylated form functions as a heretofore undescribed promoter element of a group of TATA-less CGI-associated promoters.
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6
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Yamashita W, Takahashi M, Kikkawa T, Gotoh H, Osumi N, Ono K, Nomura T. Conserved and divergent functions of Pax6 underlie species-specific neurogenic patterns in the developing amniote brain. Development 2018; 145:145/8/dev159764. [PMID: 29661783 PMCID: PMC5964652 DOI: 10.1242/dev.159764] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 03/20/2018] [Indexed: 12/20/2022]
Abstract
The evolution of unique organ structures is associated with changes in conserved developmental programs. However, characterizing the functional conservation and variation of homologous transcription factors (TFs) that dictate species-specific cellular dynamics has remained elusive. Here, we dissect shared and divergent functions of Pax6 during amniote brain development. Comparative functional analyses revealed that the neurogenic function of Pax6 is highly conserved in the developing mouse and chick pallium, whereas stage-specific binary functions of Pax6 in neurogenesis are unique to mouse neuronal progenitors, consistent with Pax6-dependent temporal regulation of Notch signaling. Furthermore, we identified that Pax6-dependent enhancer activity of Dbx1 is extensively conserved between mammals and chick, although Dbx1 expression in the developing pallium is highly divergent in these species. Our results suggest that spatiotemporal changes in Pax6-dependent regulatory programs contributed to species-specific neurogenic patterns in mammalian and avian lineages, which underlie the morphological divergence of the amniote pallial architectures. Highlighted Article: Pax6 promotes neuronal differentiation in the developing chick and mouse telencephalon via Notch inhibition, whereas its stage-specific function in RGC maintenance in the VZ is unique to mammalian neocortical progenitors.
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Affiliation(s)
- Wataru Yamashita
- Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyoku, Kyoto, 606-0823, Japan
| | - Masanori Takahashi
- Division of Biology, Center for Molecular Medicine, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi, 329-0498, Japan
| | - Takako Kikkawa
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Hitoshi Gotoh
- Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyoku, Kyoto, 606-0823, Japan
| | - Noriko Osumi
- Department of Developmental Neuroscience, United Center for Advanced Research and Translational Medicine (ART), Tohoku University School of Medicine, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi, 980-8575, Japan
| | - Katsuhiko Ono
- Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyoku, Kyoto, 606-0823, Japan
| | - Tadashi Nomura
- Developmental Neurobiology, Kyoto Prefectural University of Medicine, INAMORI Memorial Building, 1-5 Shimogamo-hangi cho, Sakyoku, Kyoto, 606-0823, Japan
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7
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Saha D, Singh A, Hussain T, Srivastava V, Sengupta S, Kar A, Dhapola P, Dhople V, Ummanni R, Chowdhury S. Epigenetic suppression of human telomerase ( hTERT) is mediated by the metastasis suppressor NME2 in a G-quadruplex-dependent fashion. J Biol Chem 2017; 292:15205-15215. [PMID: 28717007 PMCID: PMC5602382 DOI: 10.1074/jbc.m117.792077] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2017] [Revised: 07/17/2017] [Indexed: 12/11/2022] Open
Abstract
Transcriptional activation of the human telomerase reverse transcriptase (hTERT) gene, which remains repressed in adult somatic cells, is critical during tumorigenesis. Several transcription factors and the epigenetic state of the hTERT promoter are known to be important for tight control of hTERT in normal tissues, but the molecular mechanisms leading to hTERT reactivation in cancer are not well-understood. Surprisingly, here we found occupancy of the metastasis suppressor non-metastatic 2 (NME2) within the hTERT core promoter in HT1080 fibrosarcoma cells and HCT116 colon cancer cells and NME2-mediated transcriptional repression of hTERT in these cells. We also report that loss of NME2 results in up-regulated hTERT expression. Mechanistically, additional results indicated that the RE1-silencing transcription factor (REST)–lysine-specific histone demethylase 1 (LSD1) co-repressor complex associates with the hTERT promoter in an NME2-dependent way and that this assembly is required for maintaining repressive chromatin at the hTERT promoter. Interestingly, a G-quadruplex motif at the hTERT promoter was essential for occupancy of NME2 and the REST repressor complex on the hTERT promoter. In light of this mechanistic insight, we studied the effects of G-quadruplex–binding ligands on hTERT expression and observed that several of these ligands repressed hTERT expression. Together, our results support a mechanism of hTERT epigenetic control involving a G-quadruplex promoter motif, which potentially can be targeted by tailored small molecules.
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Affiliation(s)
- Dhurjhoti Saha
- From the Genomics and Molecular Medicine Unit.,Academy of Scientific & Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Mathura Road, New Delhi 110025, India and
| | - Ankita Singh
- From the Genomics and Molecular Medicine Unit.,Academy of Scientific & Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Mathura Road, New Delhi 110025, India and
| | | | | | | | - Anirban Kar
- From the Genomics and Molecular Medicine Unit
| | - Parashar Dhapola
- G.N.R. Knowledge Centre for Genome Informatics, and.,Academy of Scientific & Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Mathura Road, New Delhi 110025, India and
| | - Vishnu Dhople
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - Ramesh Ummanni
- Centre for Chemical Biology, CSIR-Indian Institute of Chemical Technology, Hyderabad 500007, India
| | - Shantanu Chowdhury
- From the Genomics and Molecular Medicine Unit, .,G.N.R. Knowledge Centre for Genome Informatics, and.,Academy of Scientific & Innovative Research (AcSIR), CSIR-Institute of Genomics and Integrative Biology, Council of Scientific and Industrial Research (CSIR), Mathura Road, New Delhi 110025, India and
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8
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Li Z, Wang Y, Kong L, Yue Z, Ma Y, Chen X. Expression of ADAM12 is regulated by E2F1 in small cell lung cancer. Oncol Rep 2016; 34:3231-7. [PMID: 26503019 DOI: 10.3892/or.2015.4317] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 09/04/2015] [Indexed: 11/06/2022] Open
Abstract
Our previous study reported that ADAM12 was highly expressed in small cell lung cancer (SCLC) and could be an effective marker for diagnosis and prognosis. Yet, the reason for the high expression of ADAM12 in SCLC requires further elucidation. Transcription factor E2F1 has been receiving increasing attention due to the complexity and diversity of its function in cancer. In the present study, the expression of ADAM12 was significantly decreased following silencing of E2F1 expression by siRNA, thus indicating that E2F1 may regulate the expression of ADAM12 at the level of transcription. Chromatin immunoprecipitation-to-sequence analysis identified three binding sites for E2F1 in the locus for ADAM12. They were Chr10: 128010444-128011026, located in the intron of ADAM12, named seq0; Chr10: 128076927‑128078127, located in the promoter of ADAM12, named seq1; and Chr10: 128086195‑128086876, located in the upstream 20 kb from the transcription start site of ADAM12, named: seq2. Dual‑luciferase reporter experiments revealed that seq1 not seq0 and seq2 was able to promote the expression of luciferase. Notably, co-transfection of E2F1 significantly increased the activity of seq1 not seq0 and seq2, but quantitative polymerase chain reaction results showed that seq0, seq1 and seq2 could recruit E2F1, indicating that the influence of E2F1 in regulating the expression of ADAM12 was complex. Sequence analysis clarified that seq1 was a part of the ADAM12 promoter, yet the functions of seq0 and seq2 were unknown. Fusion fragments containing seq0-seq1 or seq2-seq1 were analyzed in luciferase constructs. Compared with seq1 alone, the activities of these fusion fragments were non-significantly reduced. The activities of fusion fragments were significantly decreased following co-transfection with E2F1. Thus, the present findings support the conclusion that the E2F1 transcription factor regulates the expression of ADAM12 by binding differential cis-acting elements.
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9
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Comba A, Almada LL, Tolosa EJ, Iguchi E, Marks DL, Vara Messler M, Silva R, Fernandez-Barrena MG, Enriquez-Hesles E, Vrabel AL, Botta B, Di Marcotulio L, Ellenrieder V, Eynard AR, Pasqualini ME, Fernandez-Zapico ME. Nuclear Factor of Activated T Cells-dependent Down-regulation of the Transcription Factor Glioma-associated Protein 1 (GLI1) Underlies the Growth Inhibitory Properties of Arachidonic Acid. J Biol Chem 2015; 291:1933-1947. [PMID: 26601952 DOI: 10.1074/jbc.m115.691972] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Indexed: 12/11/2022] Open
Abstract
Numerous reports have demonstrated a tumor inhibitory effect of polyunsaturated fatty acids (PUFAs). However, the molecular mechanisms modulating this phenomenon are in part poorly understood. Here, we provide evidence of a novel antitumoral mechanism of the PUFA arachidonic acid (AA). In vivo and in vitro experiments showed that AA treatment decreased tumor growth and metastasis and increased apoptosis. Molecular analysis of this effect showed significantly reduced expression of a subset of antiapoptotic proteins, including BCL2, BFL1/A1, and 4-1BB, in AA-treated cells. We demonstrated that down-regulation of the transcription factor glioma-associated protein 1 (GLI1) in AA-treated cells is the underlying mechanism controlling BCL2, BFL1/A1, and 4-1BB expression. Using luciferase reporters, chromatin immunoprecipitation, and expression studies, we found that GLI1 binds to the promoter of these antiapoptotic molecules and regulates their expression and promoter activity. We provide evidence that AA-induced apoptosis and down-regulation of antiapoptotic genes can be inhibited by overexpressing GLI1 in AA-sensitive cells. Conversely, inhibition of GLI1 mimics AA treatments, leading to decreased tumor growth, cell viability, and expression of antiapoptotic molecules. Further characterization showed that AA represses GLI1 expression by stimulating nuclear translocation of NFATc1, which then binds the GLI1 promoter and represses its transcription. AA was shown to increase reactive oxygen species. Treatment with antioxidants impaired the AA-induced apoptosis and down-regulation of GLI1 and NFATc1 activation, indicating that NFATc1 activation and GLI1 repression require the generation of reactive oxygen species. Collectively, these results define a novel mechanism underlying AA antitumoral functions that may serve as a foundation for future PUFA-based therapeutic approaches.
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Affiliation(s)
- Andrea Comba
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905,; Instituto de Investigaciones en Ciencias de la Salud, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Médicas-Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Luciana L Almada
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - Ezequiel J Tolosa
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - Eriko Iguchi
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - David L Marks
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - Marianela Vara Messler
- Instituto de Investigaciones en Ciencias de la Salud, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Médicas-Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Renata Silva
- Instituto de Investigaciones en Ciencias de la Salud, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Médicas-Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Maite G Fernandez-Barrena
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905,.
| | - Elisa Enriquez-Hesles
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - Anne L Vrabel
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
| | - Bruno Botta
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza University, Center for Life Nano Science at Sapienza, Istituto Italiano di Tecnologia, 00161 Rome, Italy
| | - Lucia Di Marcotulio
- Department of Molecular Medicine, Sapienza University, Pasteur Institute/Cenci-Bolognetti Foundation, 00161 Rome, Italy, and
| | - Volker Ellenrieder
- Gastroenterology and Gastrointestinal Oncology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Aldo R Eynard
- Instituto de Investigaciones en Ciencias de la Salud, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Médicas-Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Maria E Pasqualini
- Instituto de Investigaciones en Ciencias de la Salud, Consejo Nacional de Investigaciones Científicas y Técnicas and Facultad de Ciencias Médicas-Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina
| | - Martin E Fernandez-Zapico
- From the Schulze Center for Novel Therapeutics, Division of Oncology Research, Mayo Clinic, Rochester, Minnesota 55905
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10
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Etv1 and Ewsr1 cooperatively regulate limb mesenchymal Fgf10 expression in response to apical ectodermal ridge-derived fibroblast growth factor signal. Dev Biol 2014; 394:181-90. [DOI: 10.1016/j.ydbio.2014.07.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 07/02/2014] [Accepted: 07/30/2014] [Indexed: 11/21/2022]
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11
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Down CF, Millour J, Lam EWF, Watson RJ. Binding of FoxM1 to G2/M gene promoters is dependent upon B-Myb. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1819:855-62. [PMID: 22513242 DOI: 10.1016/j.bbagrm.2012.03.008] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 03/19/2012] [Accepted: 03/20/2012] [Indexed: 01/17/2023]
Abstract
The promoters of genes which regulate entry into and progress through mitosis are typically induced maximally in G2 by transcription factors that include B-Myb and FoxM1. As FoxM1 gene transcription is a target of B-Myb, we investigated in this study how these transcription factors functionally interact to regulate these G2/M genes. Using a 3T3 cell line containing floxed B-myb alleles (B-myb(F/F)) that could be conditionally deleted by Cre recombinase, we confirmed that B-myb knockout caused both decreased mRNA expression of several G2/M genes, including FoxM1, and delayed entry into mitosis. Although FoxM1 protein expression was actually unaffected by B-myb knockout when quiescent B-myb(F/F) 3T3 cells re-entered the cell cycle upon serum-stimulation, chromatin immunoprecipitation revealed that FoxM1 binding to G2/M promoters was substantially reduced. FoxM1 transcriptional activity requires sequential phosphorylation by Cyclin-dependent kinases and Plk1, which are B-Myb target genes, and we found that phosphorylation at Plk1-specific sites was somewhat reduced upon B-myb knockout. Neither this effect nor nuclear accumulation of FoxM1, which was unaffected by B-myb knockout, was sufficient to account for the dependence on B-Myb for FoxM1 promoter binding, however. More significantly, assays using paired Birc5 (survivin) promoter-luciferase reporters with either wild-type or mutated Myb binding sites showed that FoxM1 was unable to bind and activate the promoter in the absence of B-Myb binding. Our data suggest that B-Myb is required as a pioneer factor to enable FoxM1 binding to G2/M gene promoters and explains how these transcription factors may collaborate to induce mitosis.
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Myxoid liposarcoma-associated EWSR1-DDIT3 selectively represses osteoblastic and chondrocytic transcription in multipotent mesenchymal cells. PLoS One 2012; 7:e36682. [PMID: 22570737 PMCID: PMC3343026 DOI: 10.1371/journal.pone.0036682] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 04/11/2012] [Indexed: 12/25/2022] Open
Abstract
Background Liposarcomas are the most common class of soft tissue sarcomas, and myxoid liposarcoma is the second most common liposarcoma. EWSR1-DDIT3 is a chimeric fusion protein generated by the myxoid liposarcoma-specific chromosomal translocation t(12;22)(q13;q12). Current studies indicate that multipotent mesenchymal cells are the origin of sarcomas. The mechanism whereby EWSR1-DDIT3 contributes to the phenotypic selection of target cells during oncogenic transformation remains to be elucidated. Methodology/Principal Findings Reporter assays showed that the EWSR1-DDIT3 myxoid liposarcoma fusion protein, but not its wild-type counterparts EWSR1 and DDIT3, selectively repressed the transcriptional activity of cell lineage-specific marker genes in multipotent mesenchymal C3H10T1/2 cells. Specifically, the osteoblastic marker Opn promoter and chondrocytic marker Col11a2 promoter were repressed, while the adipocytic marker Ppar-γ2 promoter was not affected. Mutation analyses, transient ChIP assays, and treatment of cells with trichostatin A (a potent inhibitor of histone deacetylases) or 5-Aza-2′-deoxycytidine (a methylation-resistant cytosine homolog) revealed the possible molecular mechanisms underlying the above-mentioned selective transcriptional repression. The first is a genetic action of the EWSR1-DDIT3 fusion protein, which results in binding to the functional C/EBP site within Opn and Col11a2 promoters through interaction of its DNA-binding domain and subsequent interference with endogenous C/EBPβ function. Another possible mechanism is an epigenetic action of EWSR1-DDIT3, which enhances histone deacetylation, DNA methylation, and histone H3K9 trimethylation at the transcriptional repression site. We hypothesize that EWSR1-DDIT3-mediated transcriptional regulation may modulate the target cell lineage through target gene-specific genetic and epigenetic conversions. Conclusions/Significance This study elucidates the molecular mechanisms underlying EWSR1-DDIT3 fusion protein-mediated phenotypic selection of putative target multipotent mesenchymal cells during myxoid liposarcoma development. A better understanding of this process is fundamental to the elucidation of possible direct lineage reprogramming in oncogenic sarcoma transformation mediated by fusion proteins.
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Gogna R, Madan E, Kuppusamy P, Pati U. Chaperoning of mutant p53 protein by wild-type p53 protein causes hypoxic tumor regression. J Biol Chem 2011; 287:2907-14. [PMID: 22147694 DOI: 10.1074/jbc.m111.317354] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Mutant (Mt) p53 abrogates tumor suppression functions of wild-type (WT) p53 through mutant-specific, gain-of-function effects, and patients bearing Mt p53 are chemoresistant. The dominant negative effect of p53 mutants results from their aggregation propensity which causes co-aggregation of WT p53. We explored the mechanism of p53 inactivation in hypoxia and hypothesized whether WT p53 could rescue Mt p53 in hypoxic tumors. WT p53 exists in mutant conformation in hypoxic core of MCF-7 solid tumors, and its conformation is oxygen-dependent. Under simulated hypoxia in cells, WT p53 undergoes conformational change in acquiring mutant conformation. An in vivo chaperone assay shows that WT p53 functions as a molecular chaperone in rescuing conformational and structural p53 mutants in cancer cells both at the transcription and proteome levels. WT p53 chaperone therapy is further shown to cause significant regression of tumor xenografts through reconversion of the mutant phenotype to wild-type p53. The chaperone function of WT p53 is directly linked to the induction of apoptosis in both cancer cells and tumor xenografts. As oncogenic p53 mutants are linked to chemoresistance in hypoxic tumors, p53 chaperone therapy will introduce new dimensions to existing cancer therapeutics. We propose that in cancer cells, WT p53 chaperoning may either exist as a cellular event to potentially reverse the dominant negative effect of its oncogenic mutants or to stabilize yet unidentified factors.
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Affiliation(s)
- Rajan Gogna
- Transcription and Human Biology Laboratory, School of Biotechnology, Jawaharlal Nehru University, New Delhi 110067, India
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14
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Johnson JL, Pillai S, Pernazza D, Sebti SM, Lawrence NJ, Chellappan SP. Regulation of matrix metalloproteinase genes by E2F transcription factors: Rb-Raf-1 interaction as a novel target for metastatic disease. Cancer Res 2011; 72:516-26. [PMID: 22086850 DOI: 10.1158/0008-5472.can-11-2647] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The retinoblastoma (Rb)-E2F transcriptional regulatory pathway plays a major role in cell-cycle regulation, but its role in invasion and metastasis is less well understood. We find that many genes involved in the invasion of cancer cells, such as matrix metalloproteinases (MMP), have potential E2F-binding sites in their promoters. E2F-binding sites were predicted on all 23 human MMP gene promoters, many of which harbored multiple E2F-binding sites. Studies presented here show that MMP genes such as MMP9, MMP14, and MMP15 which are overexpressed in non-small cell lung cancer, have multiple E2F-binding sites and are regulated by the Rb-E2F pathway. Chromatin immunoprecipitation assays showed the association of E2F1 with the MMP9, MMP14, and MMP15 promoters, and transient transfection experiments showed that these promoters are E2F responsive. Correspondingly, depletion of E2F family members by RNA interference techniques reduced the expression of these genes with a corresponding reduction in collagen degradation activity. Furthermore, activating Rb by inhibiting the interaction of Raf-1 with Rb by using the Rb-Raf-1 disruptor RRD-251 was sufficient to inhibit MMP transcription. This led to reduced invasion and migration of cancer cells in vitro and metastatic foci development in a tail vein lung metastasis model in mice. These results suggest that E2F transcription factors may play a role in promoting metastasis through regulation of MMP genes and that targeting the Rb-Raf-1 interaction is a promising approach for the treatment of metastatic disease.
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Affiliation(s)
- Jackie L Johnson
- Department of Tumor Biology, University of South Florida, Tampa, Florida, USA
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15
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Zhang W, Chen H, Wang Y, Yong W, Zhu W, Liu Y, Wagner GR, Payne RM, Field LJ, Xin H, Cai CL, Shou W. Tbx20 transcription factor is a downstream mediator for bone morphogenetic protein-10 in regulating cardiac ventricular wall development and function. J Biol Chem 2011; 286:36820-9. [PMID: 21890625 DOI: 10.1074/jbc.m111.279679] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bone morphogenetic protein 10 (BMP10) belongs to the TGFβ-superfamily. Previously, we had demonstrated that BMP10 is a key regulator for ventricular chamber formation, growth, and maturation. Ablation of BMP10 leads to hypoplastic ventricular wall formation, and elevated levels of BMP10 are associated with abnormal ventricular trabeculation/compaction and wall maturation. However, the molecular mechanism(s) by which BMP10 regulates ventricle wall growth and maturation is still largely unknown. In this study, we sought to identify the specific transcriptional network that is potentially mediated by BMP10. We analyzed and compared the gene expression profiles between α-myosin heavy chain (αMHC)-BMP10 transgenic hearts and nontransgenic littermate controls using Affymetrix mouse exon arrays. T-box 20 (Tbx20), a cardiac transcription factor, was significantly up-regulated in αMHC-BMP10 transgenic hearts, which was validated by quantitative RT-PCR and in situ hybridization. Ablation of BMP10 reduced Tbx20 expression specifically in the BMP10-expressing region of the developing ventricle. In vitro promoter analysis demonstrated that BMP10 was able to induce Tbx20 promoter activity through a conserved Smad binding site in the Tbx20 promoter proximal region. Furthermore, overexpression of Tbx20 in myocardium led to dilated cardiomyopathy that exhibited ventricular hypertrabeculation and an abnormal muscular septum, which phenocopied genetically modified mice with elevated BMP10 levels. Taken together, our findings demonstrate that the BMP10-Tbx20 signaling cascade is important for ventricular wall development and maturation.
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Affiliation(s)
- Wenjun Zhang
- Riley Heart Research Center, Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
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16
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Addis RC, Prasad MK, Yochem RL, Zhan X, Sheets TP, Axelman J, Patterson ES, Shamblott MJ. OCT3/4 regulates transcription of histone deacetylase 4 (Hdac4) in mouse embryonic stem cells. J Cell Biochem 2011; 111:391-401. [PMID: 20506506 DOI: 10.1002/jcb.22707] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
OCT3/4 is a POU domain transcription factor that is critical for maintenance of pluripotency and self-renewal by embryonic stem (ES) cells and cells of the early mammalian embryo. It has been demonstrated to bind and regulate a number of genes, often in conjunction with the transcription factors SOX2 and NANOG. In an effort to further understand this regulatory network, chromatin immunoprecipitation was used to prepare a library of DNA segments specifically bound by OCT3/4 in undifferentiated mouse ES (mES) cell chromatin. One segment corresponds to a region within the first intron of the gene encoding histone deacetylase 4 (Hdac4), a Class II histone deacetylase. This region acts as a transcriptional repressor and contains at least two functional sites that are specifically bound by OCT3/4. HDAC4 is not expressed in the nuclei of OCT3/4+ mES cells and is upregulated upon differentiation. These findings demonstrate the participation of OCT3/4 in the repression of Hdac4 in ES cells.
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Affiliation(s)
- Russell C Addis
- Department of Cell and Developmental Biology, and Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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17
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Judah D, Chang WY, Dagnino L. EBP1 is a novel E2F target gene regulated by transforming growth factor-β. PLoS One 2010; 5:e13941. [PMID: 21085677 PMCID: PMC2978110 DOI: 10.1371/journal.pone.0013941] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2010] [Accepted: 10/18/2010] [Indexed: 12/20/2022] Open
Abstract
Regulation of gene expression requires transcription factor binding to specific DNA elements, and a large body of work has focused on the identification of such sequences. However, it is becoming increasingly clear that eukaryotic transcription factors can exhibit widespread, nonfunctional binding to genomic DNA sites. Conversely, some of these proteins, such as E2F, can also modulate gene expression by binding to non-consensus elements. E2F comprises a family of transcription factors that play key roles in a wide variety of cellular functions, including survival, differentiation, activation during tissue regeneration, metabolism, and proliferation. E2F factors bind to the Erb3-binding protein 1 (EBP1) promoter in live cells. We now show that E2F binding to the EBP1 promoter occurs through two tandem DNA elements that do not conform to typical consensus E2F motifs. Exogenously expressed E2F1 activates EBP1 reporters lacking one, but not both sites, suggesting a degree of redundancy under certain conditions. E2F1 increases the levels of endogenous EBP1 mRNA in breast carcinoma and other transformed cell lines. In contrast, in non-transformed primary epidermal keratinocytes, E2F, together with the retinoblastoma family of proteins, appears to be involved in decreasing EBP1 mRNA abundance in response to growth inhibition by transforming growth factor-β1. Thus, E2F is likely a central coordinator of multiple responses that culminate in regulation of EBP1 gene expression, and which may vary depending on cell type and context.
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Affiliation(s)
- David Judah
- Department of Physiology and Pharmacology, Children Health Research Institute and Lawson Health Research Institute, University of Western Ontario, London, Canada
| | - Wing Y. Chang
- Department of Physiology and Pharmacology, Children Health Research Institute and Lawson Health Research Institute, University of Western Ontario, London, Canada
| | - Lina Dagnino
- Department of Physiology and Pharmacology, Children Health Research Institute and Lawson Health Research Institute, University of Western Ontario, London, Canada
- Department of Paediatrics, Children Health Research Institute and Lawson Health Research Institute, University of Western Ontario, London, Canada
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Singh S, Johnson J, Chellappan S. Small molecule regulators of Rb-E2F pathway as modulators of transcription. BIOCHIMICA ET BIOPHYSICA ACTA 2010; 1799:788-94. [PMID: 20637913 PMCID: PMC2997897 DOI: 10.1016/j.bbagrm.2010.07.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 06/24/2010] [Accepted: 07/08/2010] [Indexed: 12/25/2022]
Abstract
The retinoblastoma tumor suppressor protein, Rb, plays a major role in the regulation of mammalian cell cycle progression. It has been shown that Rb function is essential for the proper modulation of G1/S transition and inactivation of Rb contributes to deregulated cell proliferation. Rb exerts its cell cycle regulatory functions mainly by targeting the E2F family of transcription factors and Rb has been shown to physically interact with E2Fs 1, 2 and 3, repressing their transcriptional activity. Multiple genes involved in DNA synthesis and cell cycle progression are regulated by E2Fs, and Rb prevents their expression by inhibiting E2F activity, inducing growth arrest. It has been established that inactivation of Rb by phosphorylation, mutation, or by the interaction of viral oncoproteins leads to a release of the repression of E2F activity, facilitating cell cycle progression. Rb-mediated repression of E2F activity involves the recruitment of a variety of transcriptional co-repressors and chromatin remodeling proteins, including histone deacetylases, DNA methyltransferases and Brg1/Brm chromatin remodeling proteins. Inactivation of Rb by sequential phosphorylation events during cell cycle progression leads to a dissociation of these co-repressors from Rb, facilitating transcription. It has been found that small molecules that prevent the phosphorylation of Rb prevent the dissociation of certain co-repressors from Rb, especially Brg1, leading to the maintenance of Rb-mediated transcriptional repression and cell cycle arrest. Such small molecules have anti-cancer activities and will also act as valuable probes to study chromatin remodeling and transcriptional regulation.
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Affiliation(s)
- Sandeep Singh
- Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612
| | - Jackie Johnson
- Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612
| | - Srikumar Chellappan
- Drug Discovery Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612
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Regulation of platelet myosin light chain (MYL9) by RUNX1: implications for thrombocytopenia and platelet dysfunction in RUNX1 haplodeficiency. Blood 2010; 116:6037-45. [PMID: 20876458 DOI: 10.1182/blood-2010-06-289850] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mutations in transcription factor RUNX1 are associated with familial platelet disorder, thrombocytopenia, and predisposition to leukemia. We have described a patient with thrombocytopenia and impaired agonist-induced platelet aggregation, secretion, and glycoprotein (GP) IIb-IIIa activation, associated with a RUNX1 mutation. Platelet myosin light chain (MLC) phosphorylation and transcript levels of its gene MYL9 were decreased. Myosin IIA and MLC phosphorylation are important in platelet responses to activation and regulate thrombopoiesis by a negative regulatory effect on premature proplatelet formation. We addressed the hypothesis that MYL9 is a transcriptional target of RUNX1. Chromatin immunoprecipitation (ChIP) using megakaryocytic cells revealed RUNX1 binding to MYL9 promoter region -729/-542 basepairs (bp), which contains 4 RUNX1 sites. Electrophoretic mobility shift assay showed RUNX1 binding to each site. In transient ChIP assay, mutation of these sites abolished binding of RUNX1 to MYL9 promoter construct. In reporter gene assays, deletion of each RUNX1 site reduced activity. MYL9 expression was inhibited by RUNX1 short interfering RNA (siRNA) and enhanced by RUNX1 overexpression. RUNX1 siRNA decreased cell spreading on collagen and fibrinogen. Our results constitute the first evidence that the MYL9 gene is a direct target of RUNX1 and provide a mechanism for decreased platelet MYL9 expression, MLC phosphorylation, thrombocytopenia, and platelet dysfunction associated with RUNX1 mutations.
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20
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Ravimohan S, Gama L, Barber SA, Clements JE. Regulation of SIV mac 239 basal long terminal repeat activity and viral replication in macrophages: functional roles of two CCAAT/enhancer-binding protein beta sites in activation and interferon beta-mediated suppression. J Biol Chem 2009; 285:2258-73. [PMID: 19933495 DOI: 10.1074/jbc.m109.075929] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
CCAAT/enhancer-binding protein (C/EBP) beta and C/EBP sites in the HIV-1 long terminal repeat (LTR) are crucial for HIV-1 replication in monocyte/macrophages and for the ability of interferon beta (IFN beta) to inhibit ongoing active HIV replication in these cells. This IFN beta-mediated down-regulation involves induction of the truncated, dominant-negative isoform of C/EBP beta referred to as liver-enriched transcriptional inhibitory protein (LIP). Although binding of the C/EBP beta isoform to C/EBP sites in the simian immunodeficiency virus (SIV) LTR has previously been examined, the importance of these sites in core promoter-mediated transcription, virus replication, IFN beta-mediated regulation, and the relative binding of the two isoforms (C/EBP beta and LIP) has not been investigated. Here, we specifically examine two C/EBP sites, JC1 (-100 bp) and DS1 (+134 bp), located within the minimal region of the SIV LTR, required for core promoter-mediated transcription and virus replication in macrophages. Our studies revealed that the JC1 but not DS1 C/EBP site is important for basal level transcription, whereas the DS1 C/EBP site is imperative for productive virus replication in primary macrophages. In contrast, either JC1 or DS1 C/EBP site is sufficient to mediate IFN beta-induced down-regulation of SIV LTR activity and virus replication in these cells. We also characterized the differential binding properties of C/EBP beta and LIP to the JC1 and DS1 sites. In conjunction with previous studies from our laboratory, we demonstrate the importance of these sites in virus gene expression, and we propose a model for their role in establishing latency and persistence in macrophages in the brain.
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Affiliation(s)
- Shruthi Ravimohan
- McKusick-Nathans Institute of Genetic Medicine and Department of Molecular and Comparative Pathobiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
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21
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Ahlmann M, Varga G, Sturm K, Lippe R, Benedyk K, Viemann D, Scholzen T, Ehrchen J, Müller FU, Seidl M, Matus M, Tsokos GC, Roth J, Tenbrock K. The cyclic AMP response element modulator {alpha} suppresses CD86 expression and APC function. THE JOURNAL OF IMMUNOLOGY 2009; 182:4167-74. [PMID: 19299714 DOI: 10.4049/jimmunol.0802976] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The cAMP response element modulator (CREM)alpha is a widely expressed transcriptional repressor that is important for the termination of the T cell immune response and contributes to the abnormal T cell function in patients with systemic lupus erythematosus. We present evidence that APCs of Crem(-/-) mice express increased amounts of the costimulatory molecule CD86 and induce enhanced Ag-dependent and Ag-independent T cell proliferation. Similarly, human APCs in which CREMalpha was selectively suppressed expressed more CD86 on the surface membrane. CREMalpha was found to bind to the CD86 promoter and suppressed its activity. Transfer of APCs from Crem(-/-) mice into naive mice facilitated a significantly stronger contact dermatitis response compared with mice into which APCs from Crem(+/+) mice had been transferred. We conclude that CREMalpha is an important negative regulator of costimulation and APC-dependent T cell function both in vitro and in vivo.
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22
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Knight AS, Notaridou M, Watson RJ. A Lin-9 complex is recruited by B-Myb to activate transcription of G2/M genes in undifferentiated embryonal carcinoma cells. Oncogene 2009; 28:1737-47. [PMID: 19252525 DOI: 10.1038/onc.2009.22] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
It has recently been discovered that cell-cycle gene transcription is regulated by a core complex named LINC that switches from a transcriptionally repressive complex in G(0)-G(1) with the p130 or p107 pocket proteins and E2F4 to a transcriptionally active complex in S-G(2) containing B-Myb. We have studied the function of LINC in F9 embryonal carcinoma cells, which are distinguished by a rapid cell cycle resulting from an extremely short G(1) phase. We show that suppressing expression of the LINC component, Lin-9, in F9 cells causes arrest in mitosis, and we have used this system to screen for transcriptional targets. In these cells, B-Myb was found in complexes with Lin-9 and several other LINC constituents, however, the pocket proteins did not associate with LINC unless F9 cells were differentiated. Lin-9 and B-Myb were both required for transcription of G(2)/M genes such as Cyclin B1 and Survivin. Moreover, B-Myb was demonstrated to recruit Lin-9 to the Survivin promoter through multiple Myb-binding sites. The demonstration that a B-Myb/LINC complex is vital for progression through mitosis in cells lacking a G(1)/S checkpoint has implications for both undifferentiated embryonal cells and for cancers in which pocket protein function is compromised.
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Affiliation(s)
- A S Knight
- Department of Virology, Faculty of Medicine, Imperial College London, London, UK
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23
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Mottet D, Pirotte S, Lamour V, Hagedorn M, Javerzat S, Bikfalvi A, Bellahcène A, Verdin E, Castronovo V. HDAC4 represses p21(WAF1/Cip1) expression in human cancer cells through a Sp1-dependent, p53-independent mechanism. Oncogene 2008; 28:243-56. [PMID: 18850004 DOI: 10.1038/onc.2008.371] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Cancer cells have complex, unique characteristics that distinguish them from normal cells, such as increased growth rates and evasion of anti-proliferative signals. Global inhibition of class I and II histone deacetylases (HDACs) stops cancer cell proliferation in vitro and has proven effective against cancer in clinical trials, at least in part, through transcriptional reactivation of the p21(WAF1/Cip1)gene. The HDACs that regulate p21(WAF1/Cip1) are not fully identified. Using small interfering RNAs, we found that HDAC4 participates in the repression of p21(WAF1/Cip1) through Sp1/Sp3-, but not p53-binding sites. HDAC4 interacts with Sp1, binds and reduces histone H3 acetylation at the Sp1/Sp3 binding site-rich p21(WAF1/Cip1) proximal promoter, suggesting a key role for Sp1 in HDAC4-mediated repression of p21(WAF1/Cip1). Induction of p21(WAF1/Cip1) mediated by silencing of HDAC4 arrested cancer cell growth in vitro and inhibited tumor growth in an in vivo human glioblastoma model. Thus, HDAC4 could be a useful target for new anti-cancer therapies based on selective inhibition of specific HDACs.
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Affiliation(s)
- D Mottet
- Metastasis Research Laboratory, GIGA-Cancer (Center for Experimental Cancer Research), University of Liège, Liège, Belgium
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Green M, Panesar NK, Loewenstein PM. The transcription-repression domain of the adenovirus E1A oncoprotein targets p300 at the promoter. Oncogene 2008; 27:4446-55. [PMID: 18408753 DOI: 10.1038/onc.2008.85] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Extensive mutational/functional analysis of the transcription-repression domain encoded in the N-terminal 80 amino acids of the adenovirus E1A 243R oncoprotein suggests a model for the molecular mechanism of E1A repression: E1A accesses transcriptional co-activators such as p300 on specific promoters and then interacts with TBP to disrupt the TBP-TATA complex. In support of this model, as reported here, a basal core promoter activated by tethering p300 is repressible by E1A at the promoter level as shown by chromatin immunoprecipitation (ChIP) analysis. Sequestration of p300 by E1A does not play a significant role, as indicated by dose-response measurements. Furthermore, when the core promoter is transcriptionally activated by tethering activation domains of several transcription factors that can recruit p300 (p65, MyoD, cMyb and TFE3), transcription is repressible by E1A. However, when the core promoter is activated by factors not known to recruit p300 (USF1 and USF2), transcription is resistant to E1A repression. Finally, tethering p300 to the non-repressible adenovirus major late promoter (MLP) renders it repressible by E1A. ChIP analysis shows that E1A occupies the repressed MLP. These findings provide support for the hypothesis that p300 can serve as a scaffold for the E1A repression domain to access specific cellular gene promoters involved in growth regulation.
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Affiliation(s)
- M Green
- Institute for Molecular Virology, Saint Louis University School of Medicine, St Louis, MO 63104, USA.
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25
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Maenz B, Hekerman P, Vela EM, Galceran J, Becker W. Characterization of the human DYRK1A promoter and its regulation by the transcription factor E2F1. BMC Mol Biol 2008; 9:30. [PMID: 18366763 PMCID: PMC2292204 DOI: 10.1186/1471-2199-9-30] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 03/26/2008] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Overexpression of the human DYRK1A gene due to the presence of a third gene copy in trisomy 21 is thought to play a role in the pathogenesis of Down syndrome. The observation of gene dosage effects in transgenic mouse models implies that subtle changes in expression levels can affect the correct function of the DYRK1A gene product. We have therefore characterized the promoter of the human DYRK1A gene in order to study its transcriptional regulation. RESULTS Transcription start sites of the human DYRK1A gene are distributed over 800 bp within a region previously identified as an unmethylated CpG island. We have identified a new alternative noncoding 5'-exon of the DYRK1A gene which is located 772 bp upstream of the previously described transcription start site. Transcription of the two splicing variants is controlled by non-overlapping promoter regions that can independently drive reporter gene expression. We found no evidence of cell- or tissue-specific promoter usage, but the two promoter regions differed in their activity and their regulation. The sequence upstream of exon 1A (promoter region A) induced about 10-fold higher reporter gene activity than the sequence upstream of exon 1B (promoter region B). Overexpression of the transcription factor E2F1 increased DYRK1A mRNA levels in Saos2 and Phoenix cells and enhanced the activity of promoter region B three- to fourfold. CONCLUSION The identification of two alternatively spliced transcripts whose transcription is initiated from differentially regulated promoters regions indicates that the expression of the DYRK1A gene is subject to complex control mechanisms. The regulatory effect of E2F1 suggests that DYRK1A may play a role in cell cycle regulation or apoptosis.
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Affiliation(s)
- Barbara Maenz
- Institute of Pharmacology and Toxicology, Medical Faculty of the RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
| | - Paul Hekerman
- Institute of Pharmacology and Toxicology, Medical Faculty of the RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
| | - Eva M Vela
- Instituto de Neurociencias, CSIC – Universidad Miguel Hernandez, Campus de San Juan, 03550 San Juan (Alicante), Spain
| | - Juan Galceran
- Instituto de Neurociencias, CSIC – Universidad Miguel Hernandez, Campus de San Juan, 03550 San Juan (Alicante), Spain
| | - Walter Becker
- Institute of Pharmacology and Toxicology, Medical Faculty of the RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
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26
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E2F1 contributes to the transcriptional activation of the KIR3DL1 gene. Biochem Biophys Res Commun 2008; 370:399-403. [PMID: 18358829 DOI: 10.1016/j.bbrc.2008.03.058] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2008] [Accepted: 03/12/2008] [Indexed: 11/20/2022]
Abstract
The KIR3DL1 gene is a member of killer immunoglobulin-like receptors family, which exhibits a variegated expression pattern in NK cells and subsets of CD4(+) and CD8(+) T cells. The E2F family of transcription factors plays a crucial role in the regulation of gene expression. The present study reports a naturally occurring point mutation (TTTGGCGC-->TTCGGCGC) within a putative E2F binding site in the KIR3DL1 promoter in K562 cells. Interestingly, this mutation introduces a new methylation site. This study shows for the first time that E2F1 binds to the KIR3DL1 promoter in vivo. This point mutation and concomitantly altered methylation pattern within the E2F1 binding site abolishes their binding and reduces the promoter activity, while elevated expression of E2F1 correlates with increased promoter activity. Therefore, E2F1 contributes to the transcriptional activation of the KIR3DL1 gene.
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27
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Activator-to-repressor conversion of T-box transcription factors by the Ripply family of Groucho/TLE-associated mediators. Mol Cell Biol 2008; 28:3236-44. [PMID: 18332117 DOI: 10.1128/mcb.01754-07] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The T-box family of transcription factors, defined by a conserved DNA binding domain called the T-box, regulate various aspects of embryogenesis by activating and/or repressing downstream genes. In spite of the biological significance of the T-box proteins, how they regulate transcription remains to be elucidated. Here we show that the Groucho/TLE-associated protein Ripply converts T-box proteins from activators to repressors. In cultured cells, zebrafish Ripply1, an essential component in somite segmentation, and its structural relatives, Ripply2 and -3, suppress the transcriptional activation mediated by the T-box protein Tbx24, which is coexpressed with ripply1 during segmentation. Ripply1 associates with Tbx24 and converts it to a repressor. Ripply1 also antagonizes the transcriptional activation of another T-box protein, No tail (Ntl), the zebrafish ortholog of Brachyury. Furthermore, injection of a high dosage of ripply1 mRNA into zebrafish eggs causes defective development of the posterior trunk, similar to the phenotype observed in homozygous mutants of ntl. A mutant form of Ripply1 defective in association with Tbx24 also lacks activity in zebrafish embryos. These results indicate that the intrinsic transcriptional property of T-box proteins is controlled by Ripply family proteins, which act as specific adaptors that recruit the global corepressor Groucho/TLE to T-box proteins.
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28
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Barhl1 regulatory sequences required for cell-specific gene expression and autoregulation in the inner ear and central nervous system. Mol Cell Biol 2008; 28:1905-14. [PMID: 18212062 DOI: 10.1128/mcb.01454-07] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The development of the nervous system requires the concerted actions of multiple transcription factors, yet the molecular events leading to their expression remain poorly understood. Barhl1, a mammalian homeodomain transcription factor of the BarH class, is expressed by developing inner ear hair cells, cerebellar granule cells, precerebellar neurons, and collicular neurons. Targeted gene inactivation has demonstrated a crucial role for Barhl1 in the survival and/or migration of these sensory cells and neurons. Here we report the regulatory sequences of Barhl1 necessary for directing its proper spatiotemporal expression pattern in the inner ear and central nervous system (CNS). Using a transgenic approach, we have found that high-level and cell-specific expression of Barhl1 within the inner ear and CNS depends on both its 5' promoter and 3' enhancer sequences. Further transcriptional, binding, and mutational analyses of the 5' promoter have identified two homeoprotein binding motifs that can be occupied and activated by Barhl1. Moreover, proper Barhl1 expression in inner ear hair cells and cerebellar and precerebellar neurons requires the presence of Atoh1. Together, these data delineate useful Barhl1 regulatory sequences that direct strong and specific gene expression to inner ear hair cells and CNS sensory neurons, establish a role for autoregulation in the maintenance of Barhl1 expression, and identify Atoh1 as a key upstream regulator.
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29
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Ray SK, Leiter AB. The basic helix-loop-helix transcription factor NeuroD1 facilitates interaction of Sp1 with the secretin gene enhancer. Mol Cell Biol 2007; 27:7839-47. [PMID: 17875929 PMCID: PMC2169158 DOI: 10.1128/mcb.00438-07] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The basic helix-loop-helix transcription factor NeuroD1 is required for late events in neuronal differentiation, for maturation of pancreatic beta cells, and for terminal differentiation of enteroendocrine cells expressing the hormone secretin. NeuroD1-null mice demonstrated that this protein is essential for expression of the secretin gene in the murine intestine, and yet it is a relatively weak transcriptional activator by itself. The present study shows that Sp1 and NeuroD1 synergistically activate transcription of the secretin gene. NeuroD1, but not its widely expressed dimerization partner E12, physically interacts with the C-terminal 167 amino acids of Sp1, which include its DNA binding zinc fingers. NeuroD1 stabilizes Sp1 DNA binding to an adjacent Sp1 binding site on the promoter to generate a higher-order DNA-protein complex containing both proteins and facilitates Sp1 occupancy of the secretin promoter in vivo. NeuroD-dependent transcription of the genes encoding the hormones insulin and proopiomelanocortin is potentiated by lineage-specific homeodomain proteins. The stabilization of binding of the widely expressed transcription factor Sp1 to the secretin promoter by NeuroD represents a distinct mechanism from other NeuroD target genes for increasing NeuroD-dependent transcription.
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Affiliation(s)
- Subir K Ray
- Department of Medicine, Division of Gastroenterology, University of Massachusetts Medical School, Worcester, Massachusetts 01605, USA
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30
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Shaut CA, Saneyoshi C, Morgan EA, Knosp WM, Sexton DR, Stadler HS. HOXA13 directly regulates EphA6 and EphA7 expression in the genital tubercle vascular endothelia. Dev Dyn 2007; 236:951-60. [PMID: 17304517 DOI: 10.1002/dvdy.21077] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Hypospadias, a common defect affecting the growth and closure of the external genitalia, is often accompanied by gross enlargements of the genital tubercle (GT) vasculature. Because Hoxa13 homozygous mutant mice also exhibit hypospadias and GT vessel expansion, we examined whether genes playing a role in angiogenesis exhibit reduced expression in the GT. From this analysis, reductions in EphA6 and EphA7 were detected. Characterization of EphA6 and EphA7 expression in the GT confirmed colocalization with HOXA13 in the GT vascular endothelia. Analysis of the EphA6 and EphA7 promoter regions revealed a series of highly conserved cis-regulatory elements bound by HOXA13 with high affinity. GT chromatin immunoprecipitation confirmed that HOXA13 binds these gene-regulatory elements in vivo. In vitro, HOXA13 activates gene expression through the EphA6 and EphA7 gene-regulatory elements. Together these findings indicate that HOXA13 directly regulates EphA6 and EphA7 in the developing GT and identifies the GT vascular endothelia as a novel site for HOXA13-dependent expression of EphA6 and EphA7.
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MESH Headings
- Animals
- Base Sequence
- Binding Sites
- Cells, Cultured
- Endothelium, Vascular/embryology
- Endothelium, Vascular/metabolism
- Gene Expression Regulation, Developmental
- Genitalia/blood supply
- Genitalia/embryology
- Genitalia/metabolism
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Homeodomain Proteins/genetics
- Homeodomain Proteins/metabolism
- Homeodomain Proteins/physiology
- Mice
- Mice, Mutant Strains
- Molecular Sequence Data
- Promoter Regions, Genetic
- Receptor, EphA6/genetics
- Receptor, EphA6/metabolism
- Receptor, EphA7/genetics
- Receptor, EphA7/metabolism
- Recombinant Fusion Proteins/genetics
- Recombinant Fusion Proteins/metabolism
- Sequence Homology, Nucleic Acid
- Transfection
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Affiliation(s)
- Carley A Shaut
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, Oregon
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31
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Cvetanovic M, Rooney RJ, Garcia JJ, Toporovskaya N, Zoghbi HY, Opal P. The role of LANP and ataxin 1 in E4F-mediated transcriptional repression. EMBO Rep 2007; 8:671-7. [PMID: 17557114 PMCID: PMC1905893 DOI: 10.1038/sj.embor.7400983] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2006] [Revised: 04/10/2007] [Accepted: 04/10/2007] [Indexed: 12/29/2022] Open
Abstract
The leucine-rich acidic nuclear protein (LANP) belongs to the INHAT family of corepressors that inhibits histone acetyltransferases. The mechanism by which LANP restricts its repression to specific genes is unknown. Here, we report that LANP forms a complex with transcriptional repressor E4F and modulates its activity. As LANP interacts with ataxin 1--a protein mutated in the neurodegenerative disease spinocerebellar ataxia type 1 (SCA1)--we tested whether ataxin 1 can alter the E4F-LANP interaction. We show that ataxin 1 relieves the transcriptional repression induced by the LANP-E4F complex by competing with E4F for LANP. These results provide the first functional link, to our knowledge, between LANP and ataxin 1, and indicate a potential mechanism for the transcriptional aberrations observed in SCA1.
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Affiliation(s)
- Marija Cvetanovic
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | - Robert J Rooney
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 27710, USA
| | - Jesus J Garcia
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Nataliya Toporovskaya
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
| | - Huda Y Zoghbi
- Howard Hughes Medical Institute, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Puneet Opal
- Davee Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
- Tel: +1 312 503 4699; Fax: +1 312 503 0872; E-mail:
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32
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Yee LF, Lin PL, Stinski MF. Ectopic expression of HCMV IE72 and IE86 proteins is sufficient to induce early gene expression but not production of infectious virus in undifferentiated promonocytic THP-1 cells. Virology 2007; 363:174-88. [PMID: 17331553 DOI: 10.1016/j.virol.2007.01.036] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2006] [Revised: 01/09/2007] [Accepted: 01/30/2007] [Indexed: 12/19/2022]
Abstract
Human cytomegalovirus (HCMV) reactivation from latency causes disease in individuals who are immunocompromised or immunosuppressed. Activation of the major immediate-early (MIE) promoter is thought to be an initial step for reactivation. We determined whether expression of the MIE gene products in trans was sufficient to circumvent an HCMV latent-like state in an undifferentiated transformed human promonocytic (THP)-1 cell model system. Expression of the functional MIE proteins was achieved with a replication-defective adenovirus vector, Ad-IE1/2, which contains the MIE gene locus. Expression of the MIE proteins by Ad-IE1/2 prior to HCMV infection induced viral early gene expression accompanied by an increase in active chromatin signals. Expression of the anti-apoptotic protein encoded by UL37x1 increased viral early gene expression. However, viral DNA replication and production of infectious virus was not detected. As expected, cellular differentiation with phorbol 12-myristate 13-acetate and hydrocortisone induced virus production. Cellular differentiation is required for efficient viral reactivation.
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Affiliation(s)
- Lian-Fai Yee
- 3-701 BSB, 51 Newton Road, Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
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33
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Mussi P, Yu C, O'Malley BW, Xu J. Stimulation of Steroid Receptor Coactivator-3 (SRC-3) Gene Overexpression by a Positive Regulatory Loop of E2F1 and SRC-3. Mol Endocrinol 2006; 20:3105-19. [PMID: 16916939 DOI: 10.1210/me.2005-0522] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Abstract
Steroid receptor coactivator 3 (SRC-3, amplified in breast cancer 1, or ACTR) is a transcriptional coactivator for nuclear receptors and certain other transcription factors such as E2F1. SRC-3 is overexpressed in breast cancers, and its overexpression is sufficient to cause mammary carcinomas in vivo. However, the mechanisms controlling endogenous SRC-3 overexpression are unknown. In this study, we identified the first exon and analyzed the 5′ regulatory sequence of the SRC-3 gene. We found three evolutionarily conserved regions (ECRs) in the 5′ SRC-3 regulatory sequence, and ECR2 makes a major contribution to the SRC-3 promoter activity. The ECR2 region (bp −250/+350) contains several specificity protein 1 (Sp1) binding sites and two E2F1 binding sites. We show that E2F1 can significantly activate the ECR2 promoter activity in a dose-dependent manner. Furthermore, overexpression of E2F1 significantly increases the promoter activity of the endogenous SRC-3 gene and boosts SRC-3 expression in vivo. Conversely, knockdown of E2F1 reduces SRC-3 expression. We demonstrate that the mechanism of E2F1 activity on SRC-3 promoter is independent of the E2F binding sites but relies on the Sp1 element located at bp +150/+160. Sp1, E2F1, and SRC-3 are specifically recruited to this Sp1 site and the interaction between E2F1 and Sp1 is essential to modulate SRC-3 expression. Moreover, SRC-3 coactivates E2F1 activity and thereby additively stimulates a further increase in SRC-3 expression in vivo. These results suggest that in cells with hyperactive E2F1, such as the case encountered in breast cancer cells, there is a positive feedback regulatory loop consisting of E2F1 and SRC-3 to maintain high levels of SRC-3 and E2F1 activity, which may partially interpret the oncogenic role of SRC-3 overexpression.
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Affiliation(s)
- Paola Mussi
- Department of Molecular and Cellular Biology, Baylor College of Medicine, 1 Baylor Plaza, Houston, Texas 77030, USA
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34
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Jin VX, Rabinovich A, Squazzo SL, Green R, Farnham PJ. A computational genomics approach to identify cis-regulatory modules from chromatin immunoprecipitation microarray data--a case study using E2F1. Genome Res 2006; 16:1585-95. [PMID: 17053090 PMCID: PMC1665642 DOI: 10.1101/gr.5520206] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Advances in high-throughput technologies, such as ChIP-chip, and the completion of human and mouse genomic sequences now allow analysis of the mechanisms of gene regulation on a systems level. In this study, we have developed a computational genomics approach (termed ChIPModules), which begins with experimentally determined binding sites and integrates positional weight matrices constructed from transcription factor binding sites, a comparative genomics approach, and statistical learning methods to identify transcriptional regulatory modules. We began with E2F1 binding site information obtained from ChIP-chip analyses of ENCODE regions, from both HeLa and MCF7 cells. Our approach not only distinguished targets from nontargets with a high specificity, but it also identified five regulatory modules for E2F1. One of the identified modules predicted a colocalization of E2F1 and AP-2alpha on a set of target promoters with an intersite distance of <270 bp. We tested this prediction using ChIP-chip assays with arrays containing approximately 14,000 human promoters. We found that both E2F1 and AP-2alpha bind within the predicted distance to a large number of human promoters, demonstrating the strength of our sequence-based, unbiased, and universal protocol. Finally, we have used our ChIPModules approach to develop a database that includes thousands of computationally identified and/or experimentally verified E2F1 target promoters.
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Affiliation(s)
- Victor X. Jin
- Department of Pharmacology and the Genome Center, University of California–Davis, Davis, California 95616, USA
| | - Alina Rabinovich
- Department of Pharmacology and the Genome Center, University of California–Davis, Davis, California 95616, USA
| | - Sharon L. Squazzo
- Department of Pharmacology and the Genome Center, University of California–Davis, Davis, California 95616, USA
| | - Roland Green
- NimbleGen Systems Inc., Madison, Wisconsin 53711, USA
| | - Peggy J. Farnham
- Department of Pharmacology and the Genome Center, University of California–Davis, Davis, California 95616, USA
- Corresponding author.E-mail ; fax (530) 754-9658
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35
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Chipitsyna G, Sawaya BE, Khalili K, Amini S. Cooperativity between Rad51 and C/EBP family transcription factors modulates basal and Tat-induced activation of the HIV-1 LTR in astrocytes. J Cell Physiol 2006; 207:605-13. [PMID: 16511829 DOI: 10.1002/jcp.20612] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Transcription of the HIV-1 genome is a complex event that requires functional and physical communication of cellular proteins that recognize the LTR sequence with viral proteins, most notably, Tat. Moreover, studies have revealed the ability of Tat to induce transcription of a variety of cellular genes whose products can affect the status of cells, thus contributing to the pathogenesis of AIDS. Recently, we demonstrated that expression of Tat in astrocytes and other neural cells leads to upregulation of Rad51, a major component of DNA repair via homologous recombination. The unscheduled upregulation of Rad51, in turn, has an impact upon the extent of chromosomal abnormalities that are seen in Tat-producing cells. Here, we asked whether an elevation in Rad51 levels influences the extent of viral gene transcription in astrocytic cells. Our results demonstrate that ectopic expression of Rad51 enhances the basal- and the Tat-induced transcription of the LTR promoter. This event requires cooperativity from the C/EBP family of transcription factors including C/EBPbeta and C/EBPbeta homologous protein (CHOP). Similar to Tat, we showed that Rad51 interacts with C/EBPbeta and augments its interaction with the DNA motif spanning nucleotides -120 to -94 of the LTR. Interestingly, Tat exhibited the capacity to augment the synergism between Rad51 and C/EBPbeta. Our results also demonstrate that the level of activation of the LTR by CHOP and Tat, either alone or together, is elevated in the presence of the SW1/SNF1 chromatin remodeling complex. These observations unravel a new pathway for Tat activation of the LTR that includes the positive feedback loop involving Rad51 and C/EBPbeta family proteins.
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Affiliation(s)
- Galina Chipitsyna
- Department of Neuroscience, Center for Neurovirology, Temple University School of Medicine, Philadelphia, Pennsylvania 19122, USA
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36
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Tung L, Abdel-Hafiz H, Shen T, Harvell DME, Nitao LK, Richer JK, Sartorius CA, Takimoto GS, Horwitz KB. Progesterone receptors (PR)-B and -A regulate transcription by different mechanisms: AF-3 exerts regulatory control over coactivator binding to PR-B. Mol Endocrinol 2006; 20:2656-70. [PMID: 16762974 DOI: 10.1210/me.2006-0105] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The two, nearly identical, isoforms of human progesterone receptors (PR), PR-B and -A, share activation functions (AF) 1 and 2, yet they possess markedly different transcriptional profiles, with PR-B being much stronger transactivators. Their differences map to a unique AF3 in the B-upstream segment (BUS), at the far N terminus of PR-B, which is missing in PR-A. Combined mutation of two LXXLL motifs plus tryptophan 140 in BUS, to yield PR-BdL140, completely destroys PR-B activity, because strong AF3 synergism with downstream AF1 and AF2 is eliminated. This synergism involves cooperative interactions among receptor multimers bound at tandem hormone response elements and is transferable to AFs of other nuclear receptors. Other PR-B functions-N-/C-terminal interactions, steroid receptor coactivator-1 coactivation, ligand-dependent down-regulation-also require an intact BUS. All three are autonomous in PR-A, and map to N-terminal regions common to both PR. This suggests that the N-terminal structure adopted by the two PR is different, and that for PR-B, this is controlled by BUS. Indeed, gene expression profiling of breast cancer cells stably expressing PR-B, PR-BdL140, or PR-A shows that mutation of AF3 destroys PR-B-dependent gene transcription without converting PR-B into PR-A. In sum, AF3 in BUS plays a critical modulatory role in PR-B, and in doing so, defines a mechanism for PR-B function that is fundamentally distinct from that of PR-A.
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Affiliation(s)
- Lin Tung
- Department of Medicine, RC1 South, 12801 East 17th Avenue, P.O. Box 6511, Aurora, Colorado 80045, USA
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37
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Bindra RS, Gibson SL, Meng A, Westermark U, Jasin M, Pierce AJ, Bristow RG, Classon MK, Glazer PM. Hypoxia-induced down-regulation of BRCA1 expression by E2Fs. Cancer Res 2006; 65:11597-604. [PMID: 16357170 DOI: 10.1158/0008-5472.can-05-2119] [Citation(s) in RCA: 250] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Decreased BRCA1 expression in the absence of genetic mutation is observed frequently in sporadic cancers of the breast and other sites, although little is known regarding the mechanisms by which the expression of this gene can be repressed. Here, we show that activating and repressive E2Fs simultaneously bind the BRCA1 promoter at two adjacent E2F sites in vivo, and that hypoxia induces a dynamic redistribution of promoter occupancy by these factors resulting in the transcriptional repression of BRCA1 expression. Functionally, we show that hypoxia is associated with impaired homologous recombination, whereas the nonhomologous end-joining (NHEJ) repair pathway is unaffected under these conditions. Repression of BRCA1 expression by hypoxia represents an intriguing mechanism of functional BRCA1 inactivation in the absence of genetic mutation. We propose that hypoxia-induced decreases in BRCA1 expression and consequent suppression of homologous recombination may lead to genetic instability by shifting the balance between the high-fidelity homologous recombination pathway and the error-prone NHEJ pathway of DNA repair. Furthermore, these findings provide a novel link between E2Fs and the transcriptional response to hypoxia and provide insight into the mechanisms by which the tumor microenvironment can contribute to genetic instability in cancer.
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Affiliation(s)
- Ranjit S Bindra
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520, USA
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38
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Lyons TE, Salih M, Tuana BS. Activating E2Fs mediate transcriptional regulation of human E2F6 repressor. Am J Physiol Cell Physiol 2005; 290:C189-99. [PMID: 16107498 DOI: 10.1152/ajpcell.00630.2004] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
E2F6 is believed to repress E2F-responsive genes and therefore serve a role in cell cycle regulation. Analysis of the human E2F6 promoter region revealed the presence of two putative E2F binding sites, both of which were found to be functionally critical because deletion or mutations of these sites abolished promoter activity. Ectopic expression of E2F1 protein was found to increase E2F6 mRNA levels and significantly upregulate E2F6 promoter activity. Deletion or mutation of the putative E2F binding sites nullified the effects of E2F1 on the E2F6 promoter activity. Studies on the temporal induction of E2F family members demonstrated that the activating E2Fs, and most notably E2F1, were upregulated before E2F6 during cell cycle progression at the G1/S phase, and this coincided with the time course of induction experienced by the E2F6 promoter during the course of the cell cycle. EMSAs indicated the specific binding of nuclear complexes to the E2F6 promoter that contained E2F1-related species whose binding was specifically competed by the consensus E2F binding site. Chromatin immunoprecipitation assays with anti-E2Fs demonstrated the association of E2F family members with the E2F6 promoter in vivo. These data indicate that the expression of the E2F6 repressor is influenced at the transcriptional level by E2F family members and suggest that interplay among these transcriptional regulators, especially E2F1, may be critical for cell cycle regulation.
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Affiliation(s)
- Tarrah E Lyons
- Dept. of Cellular and Molecular Medicine, Faculty of Medicine, Univ. of Ottawa, 451 Smyth Rd., Ottawa, ON, Canada K1H 8M5
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39
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Parakati R, DiMario JX. Dynamic Transcriptional Regulatory Complexes, Including E2F4, p107, p130, and Sp1, Control Fibroblast Growth Factor Receptor 1 Gene Expression during Myogenesis. J Biol Chem 2005; 280:21284-94. [PMID: 15811856 DOI: 10.1074/jbc.m410744200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Developmentally controlled transcriptional regulation of myogenic cell proliferation and differentiation via expression of the fibroblast growth factor receptor 1 (FGFR1) gene is positively regulated by Sp1 and negatively regulated by E2F4-based transcriptional complexes. We report that p107 and p130 formed transcriptional complexes with E2F4 on the FGFR1 promoter and repressed FGFR1 gene transcription in myogenic cells. However, in Drosophila melanogaster SL2 cells, only p107 was able to repress Sp1-mediated transactivation of the FGFR1 promoter. Gel shift assays using transfected myoblast nuclear extracts showed that ectopic p107 reduced Sp1 occupancy of the proximal Sp binding site of the FGFR1 promoter, and coimmunoprecipitation studies indicated that Sp1 interacts with p107 but not with p130. Gel shift assays also demonstrated that Sp1 interacted with p107 in E2F4-p107 transcriptional complexes in myoblasts. The nature of the repressor transcriptional complex was altered in differentiated muscle fibers by the relative loss of the E2F4-p107-Sp1 transcription complex and replacement by the repressor E2F4-p130 complex. These findings demonstrate that activation and repression of FGFR1 gene transcription is governed by interplay between Sp1, p107, p130, and E2F4 in distinct transcriptional complexes during skeletal muscle development.
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MESH Headings
- Animals
- Binding Sites
- Blotting, Western
- Cell Nucleus/metabolism
- Chick Embryo
- Chromatin Immunoprecipitation
- DNA/metabolism
- DNA-Binding Proteins/physiology
- Drosophila melanogaster
- E2F4 Transcription Factor
- Gene Expression Regulation, Developmental
- Genes, Reporter
- Immunohistochemistry
- Immunoprecipitation
- Models, Biological
- Muscle, Skeletal/cytology
- Muscle, Skeletal/embryology
- Muscles/embryology
- Nuclear Proteins/physiology
- Plasmids/metabolism
- Polymerase Chain Reaction
- Promoter Regions, Genetic
- Protein Binding
- Proteins/physiology
- Receptor Protein-Tyrosine Kinases/genetics
- Receptor, Fibroblast Growth Factor, Type 1
- Receptors, Fibroblast Growth Factor/genetics
- Retinoblastoma Protein/metabolism
- Retinoblastoma-Like Protein p107
- Retinoblastoma-Like Protein p130
- Sp1 Transcription Factor/physiology
- Subcellular Fractions
- Transcription Factors/physiology
- Transcription, Genetic
- Transfection
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Affiliation(s)
- Rajini Parakati
- Department of Cell Biology and Anatomy, Chicago Medical School, North Chicago, Illinois 60064, USA
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40
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Abstract
The cell division cycle is one of the most intensively studied biological processes, yet, in spite of great effort, many questions remain as to how the cell cycle is controlled by cyclin-dependent kinases and other critical regulators. Recent functional genomic and proteomic approaches have yielded new insights into almost all aspects of cell cycle control, including transcriptional circuits, DNA replication, sister chromatid separation and regulation by environmental signals. Perhaps most notably, systematic analysis has begin to reveal meta-level connections between previously distinct sub-processes. As the interconnections between these huge datasets are beyond intuition, mathematical representation and automated analysis of functional genomic data is an urgent mandate.
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Affiliation(s)
- Mike Tyers
- Samuel Lunenfeld Research Institute, Toronto, Canada M5G 1X5.
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