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Salvatore M, Horlacher M, Marsico A, Winther O, Andersson R. Transfer learning identifies sequence determinants of cell-type specific regulatory element accessibility. NAR Genom Bioinform 2023; 5:lqad026. [PMID: 37007588 PMCID: PMC10052367 DOI: 10.1093/nargab/lqad026] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2022] [Revised: 03/01/2023] [Accepted: 03/07/2023] [Indexed: 04/03/2023] Open
Abstract
Dysfunction of regulatory elements through genetic variants is a central mechanism in the pathogenesis of disease. To better understand disease etiology, there is consequently a need to understand how DNA encodes regulatory activity. Deep learning methods show great promise for modeling of biomolecular data from DNA sequence but are limited to large input data for training. Here, we develop ChromTransfer, a transfer learning method that uses a pre-trained, cell-type agnostic model of open chromatin regions as a basis for fine-tuning on regulatory sequences. We demonstrate superior performances with ChromTransfer for learning cell-type specific chromatin accessibility from sequence compared to models not informed by a pre-trained model. Importantly, ChromTransfer enables fine-tuning on small input data with minimal decrease in accuracy. We show that ChromTransfer uses sequence features matching binding site sequences of key transcription factors for prediction. Together, these results demonstrate ChromTransfer as a promising tool for learning the regulatory code.
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Affiliation(s)
| | | | - Annalisa Marsico
- Computational Health Center, Helmholtz Center Munich, Munich, Germany
| | - Ole Winther
- Section for Computational and RNA Biology, Department of Biology, University of Copenhagen, 2200, Copenhagen, Denmark
- Section for Cognitive Systems, DTU Compute, Technical University of Denmark, 2800 Kongens Lyngby, Denmark
- Department of Genomic medicine, Rigshospitalet, 2100 Copenhagen, Denmark
| | - Robin Andersson
- To whom correspondence should be addressed. Tel: +45 35330245;
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The transcription factor E4bp4 regulates the expression and activity of Cyp3a11 in mice. Biochem Pharmacol 2019; 163:215-224. [DOI: 10.1016/j.bcp.2019.02.026] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 02/19/2019] [Indexed: 11/17/2022]
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Zhou Q, Chen J, Feng J, Wang J. E4BP4 promotes thyroid cancer proliferation by modulating iron homeostasis through repression of hepcidin. Cell Death Dis 2018; 9:987. [PMID: 30250199 PMCID: PMC6155336 DOI: 10.1038/s41419-018-1001-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 07/13/2018] [Accepted: 07/26/2018] [Indexed: 01/21/2023]
Abstract
Iron homeostasis is critical to mammals, and dysregulation in iron homeostasis usually leads to severe disorders including various cancers. Massive hepcidin secretion is an indicator of thyroid cancer, but the molecular mechanisms responsible for this dysregulation are unknown. Hepcidin secretion from thyroid cancer cells also leads to decreased expression of the iron exporter, ferroportin (FPN), and increased intracellular iron retention, which promote cancer proliferation. In this study, we examined the role of hepcidin in thyroid cancer (TC) and the molecular bases of its signaling. Synthesis of hepcidin is regulated by the BMP4/7 agonist SOSTDC1, which was downregulated in TC; SOSTDC1 downregulation was correlated with G9a-mediated hypermethylation in its promoter. The binding of G9a to the SOSTDC1 promoter requires E4BP4, which interacts with G9a to form a multi-molecular complex that contributes to SOSTDC1 silencing. Silencing of E4BP4 or G9a has similar effects to SOSTDC1 overexpression, which suppresses secretion of hepcidin and inhibits TC cell proliferation. Furthermore, our in vivo xenograft data indicated that depletion of E4BP4 also inhibits cancer growth, reduces hepcidin secretion, and reduces G9a nuclear transportation. Iron homeostasis and tumor growth in TC may be regulated by an E4BP4-dependent epigenetic mechanism. These findings suggest a new mechanism of cellular iron dysfunction through the E4BP4/G9a/SOSTDC1/hepcidin pathway, which is an essential link in TC.
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Affiliation(s)
- Qinyi Zhou
- Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Jun Chen
- Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Jialin Feng
- Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
| | - Jiadong Wang
- Department of Head and Neck Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China.
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Velmurugan BK, Chang R, Marthandam Asokan S, Chang C, Day C, Lin Y, Lin Y, Kuo W, Huang C. A minireview of E4BP4/NFIL3 in heart failure. J Cell Physiol 2018; 233:8458-8466. [DOI: 10.1002/jcp.26790] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Accepted: 04/30/2018] [Indexed: 12/13/2022]
Affiliation(s)
- Bharath Kumar Velmurugan
- Toxicology and Biomedicine Research Group, Faculty of Applied Sciences Ton Duc Thang University Ho Chi Minh City Vietnam
| | - Ruey‐Lin Chang
- College of Chinese Medicine, School of Post‐Baccalaureate Chinese Medicine China Medical University Taichung Taiwan
| | | | - Chih‐Fen Chang
- Department of Internal Medicine, Division of Cardiology Taichung Armed Force Taichung General Hospital Taichung Taiwan
| | | | - Yueh‐Min Lin
- Department of Pathology Changhua Christian Hospital Changhua Taiwan
- Department of Medical Technology, Jen‐Teh Junior College of Medicine Nursing and Management Miaoli Taiwan
| | - Yuan‐Chuan Lin
- Graduate Institute of Basic Medical Science China Medical University Taichung Taiwan
| | - Wei‐Wen Kuo
- Department of Biological Science and Technology China Medical University Taichung Taiwan
| | - Chih‐Yang Huang
- Graduate Institute of Basic Medical Science China Medical University Taichung Taiwan
- Graduate Institute of Chinese Medical Science China Medical University Taichung Taiwan
- Department of Biological Science and Technology Asia University Taichung Taiwan
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Kang G, Han HS, Koo SH. NFIL3 is a negative regulator of hepatic gluconeogenesis. Metabolism 2017; 77:13-22. [PMID: 29132537 DOI: 10.1016/j.metabol.2017.08.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2017] [Revised: 08/10/2017] [Accepted: 08/17/2017] [Indexed: 12/25/2022]
Abstract
OBJECTIVE Nuclear factor interleukin-3 regulated (NFIL3) has been known as an important transcriptional regulator of the development and the differentiation of immune cells. Although expression of NFIL3 is regulated by nutritional cues in the liver, the role of NFIL3 in the glucose metabolism has not been extensively studied. Thus, we wanted to explore the potential role of NFIL3 in the control of hepatic glucose metabolism. MATERIALS/METHODS Mouse primary hepatocytes were cultured to perform western blot analysis, Q-PCR and chromatin immunoprecipitation assay. 293T cells were cultured to perform luciferase assay. Male C57BL/6 mice (fed a normal chow diet or high fat diet for 27weeks) as well as ob/ob mice were used for experiments with adenoviral delivery. RESULTS We observed that NFIL3 reduced glucose production in hepatocytes by reducing expression of gluconeogenic gene transcription. The repression by NFIL3 required its basic leucine zipper DNA binding domain, and it competed with CREB onto the binding of cAMP response element in the gluconeogenic promoters. The protein levels of hepatic NFIL3 were decreased in the mouse models of genetic- and diet-induced obesity and insulin resistance, and ectopic expression of NFIL3 in the livers of insulin resistant mice ameliorated hyperglycemia and glucose intolerance, with concomitant reduction in expression of hepatic gluconeogenic genes. Finally, we witnessed that knockdown of NFIL3 in the livers of normal chow-fed mice promoted elevations in the glucose levels and expression of hepatic gluconeogenic genes. CONCLUSIONS In this study, we showed that NFIL3 functions as an important regulator of glucose homeostasis in the liver by limiting CREB-mediated hepatic gluconeogenesis. Thus, enhancement of hepatic NFIL3 activity in insulin resistant state could be potentially beneficial in relieving glycemic symptoms in the metabolic diseases.
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Affiliation(s)
- Geon Kang
- Division of Life Sciences, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul 02841, Republic of Korea
| | - Hye-Sook Han
- Division of Life Sciences, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul 02841, Republic of Korea
| | - Seung-Hoi Koo
- Division of Life Sciences, Korea University, 145 Anam-Ro, Seongbuk-Gu, Seoul 02841, Republic of Korea.
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Rawat A, Gopisetty G, Thangarajan R. E4BP4 is a repressor of epigenetically regulated SOSTDC1 expression in breast cancer cells. Cell Oncol (Dordr) 2014; 37:409-19. [DOI: 10.1007/s13402-014-0204-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2014] [Indexed: 01/15/2023] Open
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Keniry M, Dearth RK, Persans M, Parsons R. New Frontiers for the NFIL3 bZIP Transcription Factor in Cancer, Metabolism and Beyond. Discoveries (Craiova) 2014; 2:e15. [PMID: 26539561 PMCID: PMC4629104 DOI: 10.15190/d.2014.7] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The bZIP transcription factor NFIL3 (Nuclear factor Interleukin 3 regulated, also known as E4 binding protein 4, E4BP4) regulates diverse biological processes from circadian rhythm to cellular viability. Recently, a host of novel roles have been identified for NFIL3 in immunological signal transduction, cancer, aging and metabolism. Elucidating the signaling pathways that are impacted by NFIL3 and the regulatory mechanisms that it targets, inhibits or activates will be critical for developing a clearer picture of its physiological roles in disease and normal processes. This review will discuss the recent advances and emerging issues regarding NFIL3-mediated transcriptional regulation of CEBPb and FOXO1 activated genes and signal transduction.
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Affiliation(s)
- Megan Keniry
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Robert K Dearth
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Michael Persans
- Department of Biology, University of Texas- Pan American, 1201 W. University Dr., Edinburg, TX 78539, USA
| | - Ramon Parsons
- Department of Oncological Sciences, Icahn School of Medicine at Mount Sinai, 1470 Madison Ave HCSM 6-117, New York, NY 10029, USA
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Carey KT, Tan KH, Ng J, Liddicoat DR, Godfrey DI, Cole TJ. Nfil3 is a glucocorticoid-regulated gene required for glucocorticoid-induced apoptosis in male murine T cells. Endocrinology 2013; 154:1540-52. [PMID: 23425966 DOI: 10.1210/en.2012-1820] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Glucocorticoids (GCs) have essential roles in the regulation of development, integrated metabolism, and immune and neurological responses, and act primarily via the glucocorticoid receptor (GR). In most cells, GC treatment results in down-regulation of GR mRNA and protein levels via negative feedback mechanisms. However, in GC-treated thymocytes, GR protein levels are maintained at a high level, increasing sensitivity of thymocytes to GCs, resulting in apoptosis termed glucocorticoid-induced cell death (GICD). CD4(+)CD8(+) double-positive thymocytes and thymic natural killer T cells in particular are highly sensitive to GICD. Although GICD is exploited via the use of synthetic GC analogues in the treatment of hematopoietic malignancies, the intracellular molecular pathway of GICD is not well understood. To explore GICD in thymocytes, the authors performed whole genome expression microarray analysis in mouse GR exon 2 null vs wild-type thymus RNA 3 hours after dexamethasone treatment. Identified and validated direct GR targets included P21 and Bim, in addition to an important transcriptional regulator Nfil3, which previously has been associated with GICD and is essential for natural killer cell development in vivo. Immunostaining of NFIL3 in whole thymus localized NFIL3 primarily to the medullary region, and double labeling colocalized NFIL3 to apoptotic cells. In silico analysis revealed a putative GC response element 5 kb upstream of the Nfil3 promoter that is strongly conserved in the rat genome and was confirmed to bind GR by chromatin immunoprecipitation. The knockdown of Nfil3 mRNA levels to 20% of normal using specific small interfering RNAs abrogated GICD, indicating that NFIL3 is required for normal GICD in CTLL-2 T cells.
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Affiliation(s)
- Kirstyn T Carey
- Department of Biochemistry & Molecular Biology, Monash University, Clayton, Victoria, 3800, Australia
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E4BP4 overexpression: A protective mechanism in CD4+ T cells from SLE patients. J Autoimmun 2013; 41:152-60. [DOI: 10.1016/j.jaut.2013.01.004] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Accepted: 01/02/2013] [Indexed: 11/19/2022]
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Tong X, Zhang D, Buelow K, Guha A, Arthurs B, Brady HJM, Yin L. Recruitment of histone methyltransferase G9a mediates transcriptional repression of Fgf21 gene by E4BP4 protein. J Biol Chem 2013; 288:5417-25. [PMID: 23283977 DOI: 10.1074/jbc.m112.433482] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The liver responds to fasting-refeeding cycles by reprogramming expression of metabolic genes. Fasting potently induces one of the key hepatic hormones, fibroblast growth factor 21 (FGF21), to promote lipolysis, fatty acid oxidation, and ketogenesis, whereas refeeding suppresses its expression. We previously reported that the basic leucine zipper transcription factor E4BP4 (E4 binding protein 4) represses Fgf21 expression and disrupts its circadian oscillations in cultured hepatocytes. However, the epigenetic mechanism for E4BP4-dependent suppression of Fgf21 has not yet been addressed. Here we present evidence that histone methyltransferase G9a mediates E4BP4-dependent repression of Fgf21 during refeeding by promoting repressive histone modification. We find that Fgf21 expression is up-regulated in E4bp4 knock-out mouse liver. We demonstrate that the G9a-specific inhibitor BIX01294 abolishes suppression of the Fgf21 promoter activity by E4BP4, whereas overexpression of E4bp4 leads to increased levels of dimethylation of histone 3 lysine 9 (H3K9me2) around the Fgf21 promoter region. Furthermore, we also show that E4BP4 interacts with G9a, and knockdown of G9a blocks repression of Fgf21 promoter activity and expression in cells overexpressing E4bp4. A G9a mutant lacking catalytic activity, due to deletion of the SET domain, fails to inhibit the Fgf21 promoter activity. Importantly, acute hepatic knockdown by adenoviral shRNA targeting G9a abolishes Fgf21 repression by refeeding, concomitant with decreased levels of H3K9me2 around the Fgf21 promoter region. In summary, we show that G9a mediates E4BP4-dependent suppression of hepatic Fgf21 by enhancing histone methylation (H3K9me2) of the Fgf21 promoter.
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Affiliation(s)
- Xin Tong
- Department of Molecular and Integrative Physiology University of Michigan Medical School Ann Arbor, Michigan 48109, USA
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Beach JA, Nary LJ, Hirakawa Y, Holland E, Hovanessian R, Medh RD. E4BP4 facilitates glucocorticoid-evoked apoptosis of human leukemic CEM cells via upregulation of Bim. J Mol Signal 2011; 6:13. [PMID: 21975218 PMCID: PMC3197565 DOI: 10.1186/1750-2187-6-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 10/05/2011] [Indexed: 12/02/2022] Open
Abstract
Background Synthetic GCs serve as therapeutic agents for some lymphoid leukemias because of their ability to induce transcriptional changes via the GC receptor (GR) and trigger apoptosis. Upregulation of the BH3-only member of Bcl-2 family proteins, Bim, has been shown to be essential for GC-evoked apoptosis of leukemic lymphoblasts. Using human T cell leukemic sister clones CEM-C7-14 and CEM-C1-15, we have previously shown that the bZIP transcriptional repressor, E4BP4, is preferentially upregulated by GCs in CEM-C7-14 cells that are susceptible to GC-evoked apoptosis, but not in refractory CEM-C1-15 cells. E4BP4 is an evolutionarily conserved member of the PAR family of bZIP transcription factors related to the C. elegans death specification gene ces2. Results Mouse E4BP4 was ectopically expressed in CEM-C1-15 cells, resulting in sensitization to GC-evoked apoptosis in correlation with restoration of E4BP4 and Bim upregulation. shRNA mediated modest knockdown of E4BP4 in CEM-C7-14 cells resulted in concomitant reduction in Bim expression, although GC-evoked fold-induction and sensitivity to apoptosis was similar to parental cells. Conclusion Data presented here suggest that GC-mediated upregulation of E4BP4 facilitates Bim upregulation and apoptosis of CEM cells. Since the Bim promoter does not contain any consensus GRE or EBPRE sequences, induction of Bim may be a secondary response.
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Affiliation(s)
- Jessica A Beach
- Department of Biology, California State University Northridge, Northridge, CA 91330-8303, USA.
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Kobayashi T, Matsuoka K, Sheikh SZ, Elloumi HZ, Kamada N, Hisamatsu T, Hansen JJ, Doty KR, Pope SD, Smale ST, Hibi T, Rothman PB, Kashiwada M, Plevy SE. NFIL3 is a regulator of IL-12 p40 in macrophages and mucosal immunity. THE JOURNAL OF IMMUNOLOGY 2011; 186:4649-55. [PMID: 21383239 DOI: 10.4049/jimmunol.1003888] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Regulation of innate inflammatory responses against the enteric microbiota is essential for the maintenance of intestinal homeostasis. Key participants in innate defenses are macrophages. In these studies, the basic leucine zipper protein, NFIL3, is identified as a regulatory transcription factor in macrophages, controlling IL-12 p40 production induced by bacterial products and the enteric microbiota. Exposure to commensal bacteria and bacterial products induced NFIL3 in cultured macrophages and in vivo. The Il12b promoter has a putative DNA-binding element for NFIL3. Basal and LPS-activated NFIL3 binding to this site was confirmed by chromatin immunoprecipitation. LPS-induced Il12b promoter activity was inhibited by NFIL3 expression and augmented by NFIL3-short hairpin RNA in an Il12b-bacterial artificial chromosome-GFP reporter macrophage line. Il12b inhibition by NFIL3 does not require IL-10 expression, but a C-terminal minimal repression domain is necessary. Furthermore, colonic CD11b(+) lamina propria mononuclear cells from Nfil3(-/-) mice spontaneously expressed Il12b mRNA. Importantly, lower expression of NFIL3 was observed in CD14(+) lamina propria mononuclear cells from Crohn's disease and ulcerative colitis patients compared with control subjects. Likewise, no induction of Nfil3 was observed in colons of colitis-prone Il10(-/-) mice transitioned from germ-free to a conventional microbiota. In conclusion, these experiments characterize NFIL3 as an Il12b transcriptional inhibitor. Interactions of macrophages with the enteric microbiota induce NFIL3 to limit their inflammatory capacity. Furthermore, altered intestinal NFIL3 expression may have implications for the pathogenesis of experimental and human inflammatory bowel diseases.
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Affiliation(s)
- Taku Kobayashi
- Center for Gastrointestinal Biology and Diseases, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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MacGillavry HD, Cornelis J, van der Kallen LR, Sassen MM, Verhaagen J, Smit AB, van Kesteren RE. Genome-wide gene expression and promoter binding analysis identifies NFIL3 as a repressor of C/EBP target genes in neuronal outgrowth. Mol Cell Neurosci 2010; 46:460-8. [PMID: 21112399 DOI: 10.1016/j.mcn.2010.11.011] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Revised: 10/28/2010] [Accepted: 11/17/2010] [Indexed: 01/26/2023] Open
Abstract
NFIL3 (nuclear factor IL-3 regulated) is a multifunctional transcription factor implicated in a wide range of physiological processes, including cellular survival, circadian gene expression and natural killer cell development. We recently demonstrated that NFIL3 acts as a repressor of CREB-induced gene expression underlying the regeneration of axotomized DRG sensory neurons. In this study we performed chromatin immunoprecipitation assays combined with microarray technology (ChIP-chip) to reveal direct NFIL3 and CREB target genes in an in vitro cell model for regenerating DRG neurons. We identified 505 promoter regions bound by NFIL3 and 924 promoter regions bound by CREB. Based on promoter analysis of NFIL3-bound genes, we were able to redefine the NFIL3 consensus-binding motif. Histone H3 acetylation profiling and gene expression microarray analysis subsequently indicated that a large fraction (>60%) of NFIL3 target genes were transcriptionally silent, whereas CREB target genes in general were transcriptionally active. Only a small subset of NFIL3 target genes also bound CREB. Computational analysis indicated that a substantial number of NFIL3 target genes share a C/EBP (CCAAT/Enhancer Binding Protein) DNA binding motif. ChIP analysis confirmed binding of C/EBPs to NFIL3 target genes, and knockdown of C/EBPα, C/EBPβ and C/EBPδ, but not C/EBPγ, significantly reduced neurite outgrowth in vitro. Together, our findings show that NFIL3 is a general feed-forward repressor of basic leucine zipper transcription factors that control neurite outgrowth.
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Affiliation(s)
- Harold D MacGillavry
- Department of Molecular and Cellular Neurobiology, Center for Neurogenomics and Cognitive Research, VU University, Amsterdam, The Netherlands
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Tong X, Muchnik M, Chen Z, Patel M, Wu N, Joshi S, Rui L, Lazar MA, Yin L. Transcriptional repressor E4-binding protein 4 (E4BP4) regulates metabolic hormone fibroblast growth factor 21 (FGF21) during circadian cycles and feeding. J Biol Chem 2010; 285:36401-9. [PMID: 20851878 DOI: 10.1074/jbc.m110.172866] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Fibroblast growth factor 21 (FGF21) is a potent antidiabetic and triglyceride-lowering hormone whose hepatic expression is highly responsive to food intake. FGF21 induction in the adaptive response to fasting has been well studied, but the molecular mechanism responsible for feeding-induced repression remains unknown. In this study, we demonstrate a novel link between FGF21 and a key circadian output protein, E4BP4. Expression of Fgf21 displays a circadian rhythm, which peaks during the fasting phase and is anti-phase to E4bp4, which is elevated during feeding periods. E4BP4 strongly suppresses Fgf21 transcription by binding to a D-box element in the distal promoter region. Depletion of E4BP4 in synchronized Hepa1c1c-7 liver cells augments the amplitude of Fgf21 expression, and overexpression of E4BP4 represses FGF21 secretion from primary mouse hepatocytes. Mimicking feeding effects, insulin significantly increases E4BP4 expression and binding to the Fgf21 promoter through AKT activation. Thus, E4BP4 is a novel insulin-responsive repressor of FGF21 expression during circadian cycles and feeding.
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Affiliation(s)
- Xin Tong
- Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
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Weng YJ, Hsieh DJY, Kuo WW, Lai TY, Hsu HH, Tsai CH, Tsai FJ, Lin DY, Lin JA, Huang CY, Tung KC. E4BP4 is a cardiac survival factor and essential for embryonic heart development. Mol Cell Biochem 2010; 340:187-94. [PMID: 20186462 DOI: 10.1007/s11010-010-0417-6] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Accepted: 02/10/2010] [Indexed: 11/29/2022]
Abstract
The bZIP transcription factor E4BP4, has been demonstrated to be a survival factor in pro-B lymphocytes. GATA factors play important roles in transducing the IL-3 survival signal and transactivating the downstream survival gene, E4BP4. In heart, GATA sites are essential for proper transcription of several cardiac genes, and GATA-4 is a mediator of cardiomyocyte survival. However, the role E4BP4 plays in heart is still poorly understood. In this study, Dot-blot hybridization assays using Dig-labeled RNA probes revealed that the E4BP4 gene was expressed in cardiac tissue from several species including, monkey, dog, rabbit, and human. Western blot analysis showed that the E4BP4 protein was consistently present in all of these four species. Furthermore, immunohistochemistry revealed that the E4BP4 protein was overexpressed in diseased heart tissue in comparison with normal heart tissue. In addition, the overexpression of E4BP4 in vitro activated cell survival signaling pathway of cardiomyocytes. At last, siRNA-mediated knock down of E4BP4 in zebrafish resulted in malformed looping of the embryonic heart tube and decreased heart beating. Based on these results, we conclude that E4BP4 plays as a survival factor in heart and E4BP4 is essential for proper embryonic heart development.
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Affiliation(s)
- Yi-Jiun Weng
- Department of Veterinary Medicine, National Chung-Hsing University, No.250, Kuo-Kuang Road, 402 Taichung, Taiwan
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Rothman PB. The transcriptional regulator NFIL3 controls IgE production. TRANSACTIONS OF THE AMERICAN CLINICAL AND CLIMATOLOGICAL ASSOCIATION 2010; 121:156-171. [PMID: 20697558 PMCID: PMC2917151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Cytokines are essential modulators of the immune response that underlies the inflammatory component of atopic asthma and other allergic diseases, lnterleukin-4 is an important cytokine for the regulation of allergic immune responses. However, the molecular mechanisms that regulate the response of cells to IL-4 are still not completely defined. IL-4 plays an important role in B cell biology. It can regulate B cell differentiation. For example, IL-4 induces immunoglobulin heavy chain class switching to IgE by inducing germline immunoglobulin heavy chain transcription. It also induces expression of CD23 and MHC class II. Further understanding of the mechanisms by which IL-4 mediates these biologic responses may lead to novel mechanisms for therapeutic intervention and control of allergy. To define how different signaling pathways activated by IL-4 regulate gene transcription, we identified many differentially expressed genes by IL-4 stimulation by microarray analysis. NFIL3 (nuclear factor, interleukin 3 regulated) is the most strongly induced transcription factor by IL-4 stimulation in a STAT6-dependent manner. To analyze the role of NFIL3 in the immune system, we have generated NFIL3-deficient mice. NFIL3-deficient mice showed greatly impaired IgE production in response to antigen. NFIL3-deficient B cells fail to produce IgE in response to LPS plus IL-4. These defects may be due to the reduced production of immunoglobulin heavy chain germline epsilon transcripts in the absence of NFIL3. Moreover, NFIL3 KO mice sensitized and challenged with ovalbumin showed reduced airway hyper-responsiveness when compared to wild-type mice. Therefore, we hypothesize that NFIL3 is a critical regulator for IgE production and airway hyper-responsiveness.
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Affiliation(s)
- Paul B Rothman
- Roy J. and Lucille A. Carver College of Medicine, University of Iowa, 212 CMAB, 451 Newton Road, Iowa City, Iowa 52242, USA.
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IL-4-induced transcription factor NFIL3/E4BP4 controls IgE class switching. Proc Natl Acad Sci U S A 2009; 107:821-6. [PMID: 20080759 DOI: 10.1073/pnas.0909235107] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
IL-4 signaling promotes IgE class switching through STAT6 activation and the induction of Ig germ-line epsilon (GLepsilon) transcription. Previously, we and others identified a transcription factor, Nfil3, as a gene induced by IL-4 stimulation in B cells. However, the precise roles of nuclear factor, IL-3-regulated (NFIL3) in IL-4 signaling are unknown. Here, we report that NFIL3 is important for IgE class switching. NFIL3-deficient mice show impaired IgE class switching, and this defect is B-cell intrinsic. The induction of GLepsilon transcripts after LPS and IL-4 stimulation is significantly reduced in NFIL3-deficient B cells. Expression of NFIL3 in NFIL3-deficient B cells restores the impairment of IgE production, and overexpression of NFIL3 in the presence of cycloheximide induces GLepsilon transcripts. Moreover, NFIL3 binds to Iepsilon promoter in vivo. Together, these results identify NFIL3 as a key regulator of IL-4-induced GLepsilon transcription in response to IL-4 and subsequent IgE class switching.
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18
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Hines RN. The ontogeny of drug metabolism enzymes and implications for adverse drug events. Pharmacol Ther 2008; 118:250-67. [PMID: 18406467 DOI: 10.1016/j.pharmthera.2008.02.005] [Citation(s) in RCA: 221] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2008] [Accepted: 02/27/2008] [Indexed: 10/22/2022]
Abstract
Profound changes in drug metabolizing enzyme (DME) expression occurs during development that impacts the risk of adverse drug events in the fetus and child. A review of our current knowledge suggests individual hepatic DME ontogeny can be categorized into one of three groups. Some enzymes, e.g., CYP3A7, are expressed at their highest level during the first trimester and either remain at high concentrations or decrease during gestation, but are silenced or expressed at low levels within one to two years after birth. SULT1A1 is an example of the second group of DME. These enzymes are expressed at relatively constant levels throughout gestation and minimal changes are observed postnatally. ADH1C is typical of the third DME group that are not expressed or are expressed at low levels in the fetus, usually during the second or third trimester. Substantial increases in enzyme levels are observed within the first one to two years after birth. Combined with our knowledge of other physiological factors during early life stages, knowledge regarding DME ontogeny has permitted the development of robust physiological based pharmacokinetic models and an improved capability to predict drug disposition in pediatric patients. This review will provide an overview of DME developmental expression patterns and discuss some implications of the data with regards to drug therapy. Common themes emerging from our current knowledge also will be discussed. Finally, the review will highlight gaps in knowledge that will be important to advance this field.
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Affiliation(s)
- Ronald N Hines
- Department of Pediatrics, Medical College of Wisconsin, and Children's Research Institute, Children's Hospital and Health Systems, Milwaukee, WI 53226-4801, USA.
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19
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Kotaka M, Onishi Y, Ohno T, Akaike T, Ishida N. Identification of negative transcriptional factor E4BP4-binding site in the mouse circadian-regulated gene Mdr2. Neurosci Res 2008; 60:307-13. [PMID: 18242748 DOI: 10.1016/j.neures.2007.11.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2007] [Revised: 11/02/2007] [Accepted: 11/27/2007] [Indexed: 02/07/2023]
Abstract
The hepatic transporter Mdr2 is an ATP-binding cassette transporter which excretes phosphatidylcholine into the bile. We showed that the level of Mdr2 mRNA oscillated in circadian fashion in mouse liver whereas such oscillation was dampened in the liver of Clock mutants. To examine transcriptional regulation of the Mdr2 gene we performed luciferase reporter assays using plasmid constructs containing the 5'-flanking region of the Mdr2 gene. Reporter assays using deletion constructs demonstrated that E4BP4 represses the transcriptional activity of the promoter including the D1 and D2 sites within four putative E4BP4-binding sites. Chromatin immunoprecipitation and gel shift assays showed that E4BP4 binds to the D2 site, but not to the D1 site. These data suggested that E4BP4 is a negative transcription factor for circadian Mdr2 mRNA expression.
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Affiliation(s)
- Maki Kotaka
- Clock Cell Biology Research Group, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8566, Japan
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20
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Jagus R, Beckler GS. Overview of eukaryotic in vitro translation and expression systems. ACTA ACUST UNITED AC 2008; Chapter 11:Unit 11.1. [PMID: 18228417 DOI: 10.1002/0471143030.cb1101s00] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The ability to investigate cellular processes in vitro permits detailed analysis of the process and its molecular components. Eukaryotic translation and expression is one system that has been well studied. This overview describes the development of in vitro systems, including such approaches as continuous-flow systems, coupled transcription/translation, and the incorporation of non-natural amino acids. It also discusses molecular and genetic studies to probe translation, including post-translational fate of the synthesized proteins.
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Affiliation(s)
- Rosemary Jagus
- Center of Marine and Biotechnology and Greenebaum Cancer Center, Baltimore, Maryland, USA
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21
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Ohno T, Onishi Y, Ishida N. The negative transcription factor E4BP4 is associated with circadian clock protein PERIOD2. Biochem Biophys Res Commun 2007; 354:1010-5. [PMID: 17274955 DOI: 10.1016/j.bbrc.2007.01.084] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2007] [Accepted: 01/17/2007] [Indexed: 10/23/2022]
Abstract
The bZIP transcription factor E4BP4, is a mammalian homologue of vrille that functions as a key negative component of the circadian clock. We have shown that the E4BP4-binding site (B-site) is required in addition to a non-canonical E-box (E2 enhancer) for robust circadian Period2 (Per2) expression in the cell-autonomous clock. While the E2 enhancer and the B-site are closely situated, correlations between each component bound to the E2 enhancer and the B-site remain obscure. Here, we show that E4BP4 interacts with PER2, which represses transcriptional activity via the E-box enhancer. Interaction with PER2 required the carboxyl-terminal region that contains the repression domain of E4BP4. We also found that E4BP4 interacts with CRYPTOCHROME2 (CRY2), a key negative regulator in the mammalian circadian clock. These results suggest that E4BP4 is a component of the negative regulator complex of mammalian circadian clocks.
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Affiliation(s)
- Tomoya Ohno
- Clock Cell Biology, Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology, Central 6-5, 1-1-1 Higashi, Tsukuba, Japan
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22
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Zhang Y, Johnson K, Russell RGG, Wordsworth BP, Carr AJ, Terkeltaub RA, Brown MA. Association of sporadic chondrocalcinosis with a -4-basepair G-to-A transition in the 5'-untranslated region of ANKH that promotes enhanced expression of ANKH protein and excess generation of extracellular inorganic pyrophosphate. ACTA ACUST UNITED AC 2005; 52:1110-7. [PMID: 15818664 DOI: 10.1002/art.20978] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
OBJECTIVE Certain mutations in ANKH, which encodes a multiple-pass transmembrane protein that regulates inorganic pyrophosphate (PPi) transport, are linked to autosomal-dominant familial chondrocalcinosis. This study investigated the potential for ANKH sequence variants to promote sporadic chondrocalcinosis. METHODS ANKH variants identified by genomic sequencing were screened for association with chondrocalcinosis in 128 patients with severe sporadic chondrocalcinosis or pseudogout and in ethnically matched healthy controls. The effects of specific variants on expression of common markers were evaluated by in vitro transcription/translation. The function of these variants was studied in transfected human immortalized CH-8 articular chondrocytes. RESULTS Sporadic chondrocalcinosis was associated with a G-to-A transition in the ANKH 5'-untranslated region (5'-UTR) at 4 bp upstream of the start codon (in homozygotes of the minor allele, genotype relative risk 6.0, P = 0.0006; overall genotype association P = 0.02). This -4-bp transition, as well as 2 mutations previously linked with familial and sporadic chondrocalcinosis (+14 bp C-to-T and C-terminal GAG deletion, respectively), but not the French familial chondrocalcinosis kindred 143-bp T-to-C mutation, increased reticulocyte ANKH transcription/ANKH translation in vitro. Transfection of complementary DNA for both the wild-type ANKH and the -4-bp ANKH protein variant promoted increased extracellular PPi in CH-8 cells, but unexpectedly, these ANKH mutants had divergent effects on the expression of extracellular PPi and the chondrocyte hypertrophy marker, type X collagen. CONCLUSION A subset of sporadic chondrocalcinosis appears to be heritable via a -4-bp G-to-A ANKH 5'-UTR transition that up-regulates expression of ANKH and extracellular PPi in chondrocyte cells. Distinct ANKH mutations associated with heritable chondrocalcinosis may promote disease by divergent effects on extracellular PPi and chondrocyte hypertrophy, which is likely to mediate differences in the clinical phenotypes and severity of the disease.
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Affiliation(s)
- Yun Zhang
- Botnar Research Centre, Nuffield Orthopaedic Centre, University of Oxford, Oxford, UK
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23
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Hough C, Cuthbert CD, Notley C, Brown C, Hegadorn C, Berber E, Lillicrap D. Cell type-specific regulation of von Willebrand factor expression by the E4BP4 transcriptional repressor. Blood 2004; 105:1531-9. [PMID: 15498853 DOI: 10.1182/blood-2002-10-3093] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mechanisms of tissue-restricted patterns of von Willebrand factor (VWF) expression involve activators and repressors that limit expression to endothelial cells and megakaryocytes. The relative transcriptional activity of the proximal VWF promoter was assessed in VWF-producing and -nonproducing cells, and promoter activity was highest in endothelial cells followed by megakaryocytes. Only basal VWF promoter activity was seen in nonendothelial cells. Here we identify a negative response element located at nucleotides (nts) +96/+105 and demonstrate, using chromatin immunoprecipitation (ChIP) analysis, that in vivo this sequence interacts with the E4BP4 transcriptional repressor. Differences in size and relative abundance of nuclear E4BP4 were observed. In HepG2 cells, low levels of larger forms of E4BP4 are present that directly interact with the negative response element. In VWF-expressing cells, high levels of smaller forms predominate with no evidence of direct DNA binding. However, in endothelial cells, mutation of the VWF E4BP4 binding motif not only restores but also further elevates VWF promoter activity, suggesting that E4BP4 may be part of a coordinated binding complex. These observations implicate this binding motif in repressing both activated and basal levels of VWF transcription by different cell type-specific mechanisms, and support the hypothesis that E4BP4 sequesters negative regulators of transcription, thereby enhancing activated gene expression.
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Affiliation(s)
- Christine Hough
- The Department of Pathology and Molecular Medicine, Richardson Laboratories, Queen's University, Kingston, ON, Canada, K7L 3N6
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24
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Schröder M, Clark R, Liu CY, Kaufman RJ. The unfolded protein response represses differentiation through the RPD3-SIN3 histone deacetylase. EMBO J 2004; 23:2281-92. [PMID: 15141165 PMCID: PMC419911 DOI: 10.1038/sj.emboj.7600233] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2003] [Accepted: 04/19/2004] [Indexed: 01/08/2023] Open
Abstract
In Saccharomyces cerevisiae, splicing of HAC1 mRNA is initiated in response to the accumulation of unfolded proteins in the endoplasmic reticulum by the transmembrane kinase-endoribonuclease Ire1p. Spliced Hac1p (Hac1ip) is a negative regulator of differentiation responses to nitrogen starvation, pseudohyphal growth, and meiosis. Here we show that the RPD3-SIN3 histone deacetylase complex (HDAC), its catalytic activity, recruitment of the HDAC to the promoters of early meiotic genes (EMGs) by Ume6p, and the Ume6p DNA-binding site URS1 in the promoters of EMGs are required for nitrogen-mediated negative regulation of EMGs and meiosis by Hac1ip. Co-immunoprecipitation experiments demonstrated that Hac1ip can interact with the HDAC in vivo. Systematic analysis of double deletion strains revealed that HAC1 is a peripheral component of the HDAC. In summary, nitrogen-induced synthesis of Hac1ip and association of Hac1ip with the HDAC are physiological events in the regulation of EMGs by nutrients. These data also define for the first time a gene class that is under negative control by the UPR, and provide the framework for a novel mechanism through which bZIP proteins repress transcription.
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Affiliation(s)
- Martin Schröder
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Robert Clark
- Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Chuan Yin Liu
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI, USA
| | - Randal J Kaufman
- Department of Biological Chemistry, University of Michigan Medical Center, Ann Arbor, MI, USA
- Howard Hughes Medical Institute, University of Michigan Medical Center, Ann Arbor, MI, USA
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25
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Ozkurt IC, Tetradis S. Parathyroid hormone-induced E4BP4/NFIL3 down-regulates transcription in osteoblasts. J Biol Chem 2003; 278:26803-9. [PMID: 12743120 DOI: 10.1074/jbc.m212652200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Parathyroid hormone (PTH), a major regulator of bone metabolism, activates the PTHR1 receptor on the osteoblast plasma membrane to initiate signaling and induce transcription of primary response genes. Subsequently, primary genes with transcriptional activity regulate expression of downstream PTH targets. We have identified the adenovirus E4 promoter-binding protein/nuclear factor regulated by IL-3 (E4bp4) as a PTH-induced primary gene in osteoblasts. E4BP4 is a basic leucine zipper (bZIP) transcription factor that represses or activates transcription in non-osteoblastic cells. We report here that PTH rapidly and transiently induced E4bp4 mRNA in osteoblastic cells and that this induction did not require protein synthesis. PTH also induced E4BP4 protein synthesis and E4BP4 binding to a consensus but not to a mutant E4BP4 response element (EBPRE). E4BP4 overexpression inhibited an EBPRE-containing promoter-reporter construct, whereas PTH treatment attenuated activity of the same construct in primary mouse osteoblasts. Finally, E4BP4 overexpression inhibited PTH-induced activity of a cyclooxygenase-2 promoter-reporter construct. Our data suggest a role for E4BP4 in attenuation of PTH target gene transcription in osteoblasts.
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Affiliation(s)
- Ibrahim C Ozkurt
- Division of Diagnostic and Surgical Sciences, UCLA School of Dentistry, Los Angeles, California 90095-1668, USA
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26
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Abstract
E4BP4, a mammalian basic leucine zipper (bZIP) transcription factor, was first identified through its ability to bind and repress viral promoter sequences. Subsequently, E4BP4 and homologues in other species have been implicated in a diverse range of processes including commitment to cell survival versus apoptosis, the anti-inflammatory response and, most recently, in the mammalian circadian oscillatory mechanism. In some of these cases at least, E4BP4 appears to act antagonistically with members of the related PAR family of transcription factors with which it shares DNA-binding specificity. This diversity of function is mirrored by the regulatory pathways impinging on E4BP4, which include regulation by ras via the lymphokine IL-3 in murine B-cells, by thyroid hormone during Xenopus tail resorption, by glucocorticoids in murine fibroblasts and by calcium in rat smooth muscle cells. This article will cover the unfolding role/s of and regulation of E4BP4, E4BP4-like proteins and PAR factors in species as diverse as mouse and C. elegans.
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Affiliation(s)
- Ian G Cowell
- Department of Gene Expression and Development, The Roslin Institute (Edinburgh), Roslin, Midlothian. Scotland EH25 9PS.
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27
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Imhof MO, Chatellard P, Mermod N. Comparative study and identification of potent eukaryotic transcriptional repressors in gene switch systems. J Biotechnol 2002; 97:275-85. [PMID: 12084483 DOI: 10.1016/s0168-1656(02)00104-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In mammalian cells, proper gene regulation is achieved by the complex interplay of transcription factors that activate or repress gene expression by binding to the regulatory regions of target promoters. While transcriptional activators have been extensively characterised and classified into functional groups, relatively little is known about the comparative strength and cell type-specificity of transcriptional repressors. Here, we have compared the ability of a series of eukaryotic repression domains to silence basal and activated transcription. A series of the most potent repression domains was further tested in the context of a gene therapy gene-switch system in various cell types. The results indicate that the analysed repression domains exert varying silencing activities in different promoter contexts. Furthermore, their potential for gene silencing varies also depending on the cellular context. When multimerised within one chimeric repressor protein, particular combinations of repressor domains were found to display synergistic repressing effects and efficient repression in a panel of cell lines. This approach thus allowed the identification of transcriptional repressors that are both potent and versatile in terms of cellular specificity as a basis for gene switch systems.
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Affiliation(s)
- Markus O Imhof
- Laboratory of Molecular Biotechnology, Center for Biotechnology UNIL-EPFL and Institute of Animal Biology, University of Lausanne, 1015, Lausanne, Switzerland
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28
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Cowell IG, Okorokov AL, Cutts SA, Padget K, Bell M, Milner J, Austin CA. Human topoisomerase IIalpha and IIbeta interact with the C-terminal region of p53. Exp Cell Res 2000; 255:86-94. [PMID: 10666337 DOI: 10.1006/excr.1999.4772] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The p53 tumor suppressor protein is a critical regulator of cell cycle progression and apoptosis following exposure of cells to DNA damaging agents such as ionizing radiation or anticancer drugs. An important group of anticancer drugs, including compounds such as etoposide and doxorubicin (Adriamycin), interacts with DNA topoisomerase II (topo II), causing the accumulation of enzyme-DNA adducts that ultimately lead to double-strand breaks and cell death via apoptosis. Human topo IIbeta has previously been shown to interact with p53, and we have extended this analysis to show that both topo IIalpha and IIbeta interact with p53 in vivo and in vitro. Furthermore, we show that the regulatory C-terminal basic region of p53 (residues 364-393) is necessary and sufficient for interaction with DNA topo II.
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Affiliation(s)
- I G Cowell
- School of Biochemistry and Genetics, University of Newcastle, Newcastle upon Tyne, NE2 4HH, United Kingdom
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29
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Ishida H, Ueda K, Ohkawa K, Kanazawa Y, Hosui A, Nakanishi F, Mita E, Kasahara A, Sasaki Y, Hori M, Hayashi N. Identification of multiple transcription factors, HLF, FTF, and E4BP4, controlling hepatitis B virus enhancer II. J Virol 2000; 74:1241-51. [PMID: 10627534 PMCID: PMC111458 DOI: 10.1128/jvi.74.3.1241-1251.2000] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Hepatitis B virus (HBV) enhancer II (EnII) is a hepatotropic cis element which is responsible for the hepatocyte-specific gene expression of HBV. Multiple transcription factors have been demonstrated to interact with this region. In this study, the region from HBV nucleotides (nt) 1640 to 1663 in EnII was demonstrated to be essential for enhancer activity and to be another target sequence of putative transcription factors. To elucidate the factors which bind to this region, we used a yeast one-hybrid screening system and cloned three transcription factors, HLF, FTF, and E4BP4, from a human adult liver cDNA library. All of these factors had binding affinity to the sequence from nt 1640 to 1663. Investigation of the effects of these factors on transcriptional regulation revealed that HLF and FTF had stimulatory activity on nt 1640 to 1663, whereas E4BP4 had a suppressing effect. FTF coordinately activated both 3. 5-kb RNA and 2.4/2.1-kb RNA transcription in a transient transfection assay with an HBV expression vector. HLF, however, activated only 3.5-kb RNA transcription, and in primer extension analysis, HLF strongly stimulated the synthesis of pregenome RNA compared to precore RNA. Thus, FTF stimulated the activity of the second enhancer, while HLF stimulated the activity of the core upstream regulatory sequence, which affects only the core promoter, and had a dominant effect on the pregenome RNA synthesis.
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Affiliation(s)
- H Ishida
- Department of Internal Medicine and Therapeutics, Osaka University Graduate School of Medicine, Suita, Osaka 565-0871, Japan
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30
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McKay LM, Carpenter B, Roberts SG. Evolutionary conserved mechanism of transcriptional repression by even-skipped. Nucleic Acids Res 1999; 27:3064-70. [PMID: 10454601 PMCID: PMC148531 DOI: 10.1093/nar/27.15.3064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Even-skipped (Eve) is a transcriptional repressor involved in segment formation in Drosophila melano-gaster. In order to gain further insights into the mechanism of action of Eve we tested whether it would function as a transcriptional repressor in mammalian cells. We found that Eve was indeed a potent repressor in two different mammalian cell types and at several promoters. In vitro transcription assays confirmed that Eve directly represses transcription initiation when specifically targeted to a promoter. We also found that, unlike the case with transcriptional activators, Eve does not repress transcription synergistically. Analysis of the effect of Eve on preinitiation complex assembly in a crude HeLa cell nuclear extract demonstrated that the Eve repression domain functions by preventing the assembly of TFIID with the promoter. Our data support the hypothesis that Eve contains an active repression domain that functions specifically to prevent preinitiation complex formation.
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Affiliation(s)
- L M McKay
- Division of Gene Expression, Department of Biochemistry, Wellcome Trust Building, University of Dundee, Dundee DD1 5EH, UK
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31
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Lai CK, Ting LP. Transcriptional repression of human hepatitis B virus genes by a bZIP family member, E4BP4. J Virol 1999; 73:3197-209. [PMID: 10074173 PMCID: PMC104083 DOI: 10.1128/jvi.73.4.3197-3209.1999] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Box alpha is an essential element of both the upstream regulatory sequence of the core promoter and the second enhancer, which positively regulate the transcription of human hepatitis B virus (HBV) genes. In this paper, we describe the cloning and characterization of a box alpha binding protein, E4BP4. E4BP4 is a bZIP type of transcription factor. Overexpression of E4BP4 represses the stimulating activity of box alpha in the upstream regulatory sequence of the core promoter and the second enhancer in differentiated human hepatoma cell lines. E4BP4 can also suppress the transcription of HBV genes and the production of HBV virions in a transient-transfection system that mimics the viral infection in vivo. Expression of an E4BP4 antisense transcript can, instead, elevate the transcription of the core promoter. A low abundance of E4BP4 protein and mRNA in differentiated human hepatoma cell lines is detected, and E4BP4 is not a major component of box alpha binding proteins in untransfected differentiated human hepatoma cell lines. C/EBPalpha and C/EBPbeta, in contrast, are major components of the box alpha binding activity present in nuclear extracts. E4BP4 has a stronger binding affinity towards box alpha than the endogenous box alpha binding activity present in nuclear extracts. Structure and function analysis of E4BP4 reveals that DNA binding activity is sufficient to confer the negative regulatory function of E4BP4. These results indicate that binding site occlusion is the mechanism whereby E4BP4 suppresses transcription in HBV.
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Affiliation(s)
- C K Lai
- Institute of Microbiology and Immunology, School of Life Science, National Yang-Ming University, Shih-Pai, Taipei 11221, Taiwan, Republic of China
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32
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Osada S, Ikeda T, Xu M, Nishihara T, Imagawa M. Identification of the transcriptional repression domain of nuclear factor 1-A. Biochem Biophys Res Commun 1997; 238:744-7. [PMID: 9325160 DOI: 10.1006/bbrc.1997.7382] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
We previously showed that nuclear factor 1-A (NF1-A) binds to the silencer elements in the glutathione transferase P (GST-P) gene, and the carboxy terminal region of NF1-A represses the transcription activity of human metallothionein IIA (hMTIIA) promoter. In this study, we identified a repression region which is divided into two 100 amino acid domains (RD1 and RD2). RD1 increased the repression activity of RD2 to the hMTIIA promoter activity. The NF1-A repression domain inhibited the promoter activities of not only the hMTIIA gene but also those of the GST-P and CCAAT/enhancer binding protein delta genes. RD1 and RD2 had abundant serine and glycine residues, and proline and serine residues, respectively. Whereas some repression domains identified previously are enriched with alanine, proline, or serine, and are associated with the general transcription factors, the NF1-A repression domains did not interact with transcription factor IIB, TATA-binding protein (TBP), or TBP-associated factors in vitro.
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Affiliation(s)
- S Osada
- Laboratory of Environmental Biochemistry, School of Pharmaceutical Sciences, Osaka University, Suita, Japan
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