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Chen C, Lin HG, Yao Z, Jiang YL, Yu HJ, Fang J, Li WN. Transcription factor glucocorticoid modulatory element-binding protein 1 promotes hepatocellular carcinoma progression by activating Yes-associate protein 1. World J Gastrointest Oncol 2023; 15:988-1004. [PMID: 37389116 PMCID: PMC10302989 DOI: 10.4251/wjgo.v15.i6.988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 03/18/2023] [Accepted: 04/12/2023] [Indexed: 06/14/2023] Open
Abstract
BACKGROUND Glucocorticoid modulatory element-binding protein 1 (GMEB1), which has been identified as a transcription factor, is a protein widely expressed in various tissues. Reportedly, the dysregulation of GMEB1 is linked to the genesis and development of multiple cancers.
AIM To explore GMEB1’s biological functions in hepatocellular carcinoma (HCC) and figuring out the molecular mechanism.
METHODS GMEB1 expression in HCC tissues was analyzed employing the StarBase database. Immunohistochemical staining, Western blotting and quantitative real-time PCR were conducted to examine GMEB1 and Yes-associate protein 1 (YAP1) expression in HCC cells and tissues. Cell counting kit-8 assay, Transwell assay and flow cytometry were utilized to examine HCC cell proliferation, migration, invasion and apoptosis, respectively. The JASPAR database was employed for predicting the binding site of GMEB1 with YAP1 promoter. Dual-luciferase reporter gene assay and chromatin immunoprecipitation-qPCR were conducted to verify the binding relationship of GMEB1 with YAP1 promoter region.
RESULTS GMEB1 was up-regulated in HCC cells and tissues, and GMEB1 expression was correlated to the tumor size and TNM stage of HCC patients. GMEB1 overexpression facilitated HCC cell multiplication, migration, and invasion, and suppressed the apoptosis, whereas GMEB1 knockdown had the opposite effects. GMEB1 bound to YAP1 promoter region and positively regulated YAP1 expression in HCC cells.
CONCLUSION GMEB1 facilitates HCC malignant proliferation and metastasis by promoting the transcription of the YAP1 promoter region.
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Affiliation(s)
- Cheng Chen
- Department of Medical Oncology, Zhejiang Xiaoshan Hospital, Hangzhou 311202, Zhejiang Province, China
| | - Hai-Guan Lin
- Department of General Surgery, People’s Liberation Army Strategic Support Force Characteristic Medical Center, Beijing 100101, China
| | - Zheng Yao
- Department of Radiation Oncology, Cancer Hospital of The University of Chinese Academy of Sciences, Hangzhou 310022, Zhejiang Province, China
| | - Yi-Ling Jiang
- Department of Medical Oncology, Zhejiang Xiaoshan Hospital, Hangzhou 311202, Zhejiang Province, China
| | - Hong-Jin Yu
- Department of Medical Oncology, Zhejiang Xiaoshan Hospital, Hangzhou 311202, Zhejiang Province, China
| | - Jing Fang
- Department of Medical Oncology, Zhejiang Xiaoshan Hospital, Hangzhou 311202, Zhejiang Province, China
| | - Wei-Na Li
- Department of Medical Oncology, Zhejiang Xiaoshan Hospital, Hangzhou 311202, Zhejiang Province, China
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Ali MW, Patro CPK, Zhu JJ, Dampier CH, Plummer SJ, Kuscu C, Adli M, Lau C, Lai RK, Casey G. A functional variant on 20q13.33 related to glioma risk alters enhancer activity and modulates expression of multiple genes. Hum Mutat 2020; 42:77-88. [PMID: 33169458 PMCID: PMC7839675 DOI: 10.1002/humu.24134] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 10/15/2020] [Accepted: 10/30/2020] [Indexed: 12/22/2022]
Abstract
Genome‐wide association studies (GWAS) have identified single‐nucleotide polymorphisms (SNPs) associated with glioma risk on 20q13.33, but the biological mechanisms underlying this association are unknown. We tested the hypothesis that a functional SNP on 20q13.33 impacted the activity of an enhancer, leading to an altered expression of nearby genes. To identify candidate functional SNPs, we identified all SNPs in linkage disequilibrium with the risk‐associated SNP rs2297440 that mapped to putative enhancers. Putative enhancers containing candidate functional SNPs were tested for allele‐specific effects in luciferase enhancer activity assays against glioblastoma multiforme (GBM) cell lines. An enhancer containing SNP rs3761124 exhibited allele‐specific effects on activity. Deletion of this enhancer by CRISPR‐Cas9 editing in GBM cell lines correlated with an altered expression of multiple genes, including STMN3, RTEL1, RTEL1‐TNFRSF6B, GMEB2, and SRMS. Expression quantitative trait loci (eQTL) analyses using nondiseased brain samples, isocitrate dehydrogenase 1 (IDH1) wild‐type glioma, and neurodevelopmental tissues showed STMN3 to be a consistent significant eQTL with rs3761124. RTEL1 and GMEB2 were also significant eQTLs in the context of early CNS development and/or in IDH1 wild‐type glioma. We provide evidence that rs3761124 is a functional variant on 20q13.33 related to glioma/GBM risk that modulates the expression of STMN3 and potentially other genes across diverse cellular contexts.
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Affiliation(s)
- Mourad Wagdy Ali
- Department of Public Health Sciences, Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia, USA
| | - C Pawan K Patro
- Department of Neurology, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | | | - Christopher H Dampier
- Department of Public Health Sciences, Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia, USA
| | - Sarah J Plummer
- Department of Public Health Sciences, Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia, USA
| | - Cem Kuscu
- Department of Surgery, James D. Eason Transplant Research Institute, University of Tennessee, Memphis, Tennessee, USA
| | - Mazhar Adli
- Department of Obstetrics and Gynecology, Robert Lurie Comprehensive Cancer Center, Feinberg School of Medicine at Northwestern University, Chicago, Illinois, USA
| | - Ching Lau
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA
| | - Rose K Lai
- Departments of Neurology and Preventive Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California, USA
| | - Graham Casey
- Department of Public Health Sciences, Center for Public Health Genomics, University of Virginia, Charlottesville, Virginia, USA
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The Speckled Protein (SP) Family: Immunity's Chromatin Readers. Trends Immunol 2020; 41:572-585. [PMID: 32386862 DOI: 10.1016/j.it.2020.04.007] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2019] [Revised: 03/25/2020] [Accepted: 04/04/2020] [Indexed: 01/25/2023]
Abstract
Chromatin 'readers' are central interpreters of the epigenome that facilitate cell-specific transcriptional programs and are therapeutic targets in cancer and inflammation. The Speckled Protein (SP) family of chromatin 'readers' in humans consists of SP100, SP110, SP140, and SP140L. SPs possess functional domains (SAND, PHD, bromodomain) that dock to DNA or post-translationally modified histones and a caspase activation and recruitment domain (CARD) to promote multimerization. Mutations within immune expressed SPs associate with numerous immunological diseases including Crohn's disease, multiple sclerosis, chronic lymphocytic leukemia, veno-occlusive disease with immunodeficiency, as well as Mycobacterium tuberculosis infection, underscoring their importance in immune regulation. In this review, we posit that SPs are central chromatin regulators of gene silencing that establish immune cell identity and function.
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Glucocorticoid modulatory element-binding protein 1 (GMEB1) interacts with the de-ubiquitinase USP40 to stabilize CFLAR L and inhibit apoptosis in human non-small cell lung cancer cells. J Exp Clin Cancer Res 2019; 38:181. [PMID: 31046799 PMCID: PMC6498657 DOI: 10.1186/s13046-019-1182-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/17/2019] [Indexed: 02/05/2023] Open
Abstract
Background GMEB1 was originally identified via its interaction with GMEB2, which binds to the promoter region of the tyrosine aminotransferase (TAT) gene and modulates transactivation of the glucocorticoid receptor gene. In the cytosol, GMEB1 interacts with and inhibits CASP8, but the molecular mechanism is currently unknown. Methods Human non-small cell lung cancer cells and 293FT cells were used to investigate the function of GMEB1/USP40/CFLARL complex by WB, GST Pull-Down Assay, Immunoprecipitation, Immunofluorescence and Flow cytometry analysis. A549 cells overexpressing green fluorescent protein and GMEB1 shRNA were used for tumor xenograft using female athymic nu/nu 4-week-old mice. Results We found GMEB1 interacted with CFLARL (also known as c-FLIPL) in the cytosol and promoted its stability. USP40 targeted CFLARL for K48-linked de-ubiquitination. GMEB1 promoted the binding of USP40 to CFLARL. USP40 knockdown did not increase CFLARL protein level despite GMEB1 overexpression, suggesting GMEB1 promotes CFLARL stability via USP40. Additionally, GMEB1 inhibited the activation of pro-caspase 8 and apoptosis in non-small cell lung cancer (NSCLC) cell via CFLARL stabilization. Also, GMEB1 inhibited the formation of DISC upon TRAIL activation. CFLARL enhanced the binding of GMEB1 and CASP8. Downregulation of GMEB1 inhibited A549 xenograft tumor growth in vivo. Conclusions Our findings show the de-ubiquitinase USP40 regulates the ubiquitination and degradation of CFLARL; and GMEB1 acts as a bridge protein for USP40 and CFLARL. Mechanistically, we found GMEB1 inhibits the activation of CASP8 by modulating ubiquitination and degradation of CFLARL. These findings suggest a novel strategy to induce apoptosis through CFLARL targeting in human NSCLC cells. Electronic supplementary material The online version of this article (10.1186/s13046-019-1182-3) contains supplementary material, which is available to authorized users.
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Abstract
The sperm/oocyte decision in the hermaphrodite germline of Caenorhabditis elegans provides a powerful model for the characterization of stem cell fate specification and differentiation. The germline sex determination program that governs gamete fate has been well studied, but direct mediators of cell-type-specific transcription are largely unknown. We report the identification of spe-44 as a critical regulator of sperm gene expression. Deletion of spe-44 causes sperm-specific defects in cytokinesis, cell cycle progression, and organelle assembly resulting in sterility. Expression of spe-44 correlates precisely with spermatogenesis and is regulated by the germline sex determination pathway. spe-44 is required for the appropriate expression of several hundred sperm-enriched genes. The SPE-44 protein is restricted to the sperm-producing germline, where it localizes to the autosomes (which contain sperm genes) but is excluded from the transcriptionally silent X chromosome (which does not). The orthologous gene in other Caenorhabditis species is similarly expressed in a sex-biased manner, and the protein likewise exhibits autosome-specific localization in developing sperm, strongly suggestive of an evolutionarily conserved role in sperm gene expression. Our analysis represents the first identification of a transcriptional regulator whose primary function is the control of gamete-type-specific transcription in this system. Stem cells give rise to the variety of specialized cell types within an organism. The decision to adopt a particular cell fate, a process known as specification or determination, requires the coordinated expression of all of the genes needed for that specialized cell to develop and function properly. Understanding the mechanisms that govern these patterns of gene expression is critical to our understanding of stem cell fate specification. We study this process in a nematode species that makes both sperm and eggs from the same stem cell population. We have identified a gene, named spe-44, that is required for the proper expression of sperm genes (but not egg genes). Mutation in spe-44 produces sterile sperm with developmental defects. spe-44 is controlled by factors that govern the sperm/egg decision, and its function in controlling sperm gene expression appears to be conserved in other nematode species.
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6
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Bryzgalov LO, Ershov NI, Ilnitskaya SI. FOXA transcription factors determine the amplitude of glucocorticoid induction of tyrosine aminotransferase in mice. Bull Exp Biol Med 2008; 144:722-4. [PMID: 18683506 DOI: 10.1007/s10517-007-0415-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
o-Aminoazotoluene was more potent than 3'-methyl-4-dimethylaminoazobenzene in modulating glucocorticoid induction of tyrosine aminotransferase and DNA-binding activity of FOXA (HNF3) in 12-day-old ICR mice. In adult animals, induction of tyrosine aminotransferase and FOXA activity were modulated by o-aminoazotoluene, while 3'-methyl-4-dimethylaminoazobenzene was ineffective. Our results suggest that FOXA proteins determine glucocorticoid induction of tyrosine aminotransferase in mice (similarly to rats).
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Affiliation(s)
- L O Bryzgalov
- Institute of Cytology and Genetics, Siberian Division of the Russian Academy of Sciences, Novosibirsk.
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Simons SS. What goes on behind closed doors: physiological versus pharmacological steroid hormone actions. Bioessays 2008; 30:744-56. [PMID: 18623071 DOI: 10.1002/bies.20792] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Steroid-hormone-activated receptor proteins are among the best-understood class of factors for altering gene transcription in cells. Steroid receptors are of major importance in maintaining normal human physiology by responding to circulating concentrations of steroid in the nM range. Nonetheless, most studies of steroid receptor action have been conducted using the supra-physiological conditions of saturating concentrations (> or =100 nM) of potent synthetic steroid agonists. Here we summarize the recent developments arising from experiments using two clinically relevant conditions: subsaturating concentrations of agonist (to mimic the circulating concentrations in mammals) and saturating concentrations of antagonists (which are employed in endocrine therapies to block the actions of endogenous steroids). These studies have revealed new facets of steroid hormone action that could not be uncovered by conventional experiments with saturating concentrations of agonist steroids, such as a plethora of factors/conditions for the differential control of gene expression by physiological levels of steroid, a rational approach for examining the gene-specific variations in partial agonist activity of antisteroids, and a dissociation of steroid potency and efficacy that implies the existence of separate, and possibly novel, mechanistic steps and cofactors.
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Affiliation(s)
- S Stoney Simons
- Steroid Hormones Section, Bldg 10, Room 8N-307B, NIDDK/CEB, NIH, Bethesda, MD 20892-1772, USA
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Szapary D, Song LN, He Y, Simons SS. Differential modulation of glucocorticoid and progesterone receptor transactivation. Mol Cell Endocrinol 2008; 283:114-26. [PMID: 18215457 PMCID: PMC2275900 DOI: 10.1016/j.mce.2007.11.031] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 11/29/2007] [Indexed: 01/13/2023]
Abstract
The determinants of the different biological activities of progesterone receptors (PRs) vs. glucocorticoid receptors (GRs), which bind to the same DNA sequences, remain poorly understood. The mechanisms by which differential expression of a common target gene can be achieved by PR and GR include unequal agonist steroid concentrations for half maximal induction (EC50) and dissimilar amounts of residual partial agonist activity for antisteroids in addition to the more common changes in total gene induction, or Vmax. Several factors are known to alter some or all of these three parameters for GR-regulated gene induction and some (i.e., the corepressors NCoR and SMRT) modulate the EC50 and partial agonist activity for GR and PR induction of the same gene in opposite directions. The current study demonstrates that other factors known to modulate GR properties (GME, GMEB-2, Ubc9, and STAMP) can also differentially interact with PRs or alter several of the above induction parameters under otherwise identical conditions. These results support the hypothesis that the modulation of EC50, partial agonist activity, and Vmax by a given factor is not limited to one receptor in a specific cell line. Furthermore, the number of factors that unequally modulate PR and GR induction parameters is now greatly expanded, thereby increasing the possible mechanisms for differential gene regulation by PRs vs. GRs.
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Affiliation(s)
- Daniele Szapary
- Steroid Hormones Section, NIDDK/CEB, National Institutes of Health, Bethesda, MD 20892-1772, United States
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9
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Tsuruma K, Nakagawa T, Morimoto N, Minami M, Hara H, Uehara T, Nomura Y. Glucocorticoid modulatory element-binding protein 1 binds to initiator procaspases and inhibits ischemia-induced apoptosis and neuronal injury. J Biol Chem 2006; 281:11397-404. [PMID: 16497673 DOI: 10.1074/jbc.m510597200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Caspases are divided into two classes: initiator caspases, which include caspase-8 and -9 and possess long prodomains, and effector caspases, which include caspase-3 and -7 and possess short prodomains. Recently, we demonstrated that glucocorticoid modulatory element-binding protein 1 (GMEB1) interacts with the prodomain of procaspase-2, thereby disrupting its autoactivation and the induction of apoptosis. Here we show that GMEB1 is also capable of binding to procaspase-8 and -9. GMEB1 attenuated the Fas-mediated activation of these caspases and the subsequent apoptosis. The knockdown of endogenous GMEB1 using RNA interference revealed that cells with decreased GMEB1 expression are more sensitive to stress and undergo accelerated apoptosis. Transgenic mice expressing a neurospecific GMEB1 had smaller cerebral infarcts and less brain swelling than wild-type mice in response to transient focal ischemia. These results suggest that GMEB1 is an endogenous regulator that selectively binds to initiator procaspases and inhibits caspase-induced apoptosis.
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Affiliation(s)
- Kazuhiro Tsuruma
- Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Hokkaido University, N12W6, Sapporo 060-0812, Japan
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10
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Merkulova TI, Kropachev KY, Timofeeva OA, Vasiliev GV, Levashova ZB, Ilnitskaya SI, Kobzev VF, Pakharukova MY, Bryzgalov LO, Kaledin VI. Species-specific effects of the hepatocarcinogens 3'-methyl-4-dimethyl-aminoazobenzene and ortho-aminoazotoluene in mouse and rat liver. Mol Carcinog 2006; 44:223-32. [PMID: 16267830 DOI: 10.1002/mc.20090] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The effects of rat-specific hepatocarcinogen 3'-methyl-4-dimethylaminoazobenzene (3'-MeDAB), mouse-specific hepatocarcinogen ortho-aminoazotoluene (OAT), non-species-specific hepatocarcinogen diethylnitrosamine (DENA), and non-carcinogenic 4'-methyl-4-dimethylaminoazobenzene (4'-MeDAB) on glucocorticoid induction of tyrosine aminotransferase (TAT) and DNA-binding activity of hepatocyte nuclear factor 3 (HNF3) family of transcription factors were investigated with carcinogen-susceptible and -resistant animals. Species-specific hepatocarcinogens 3'-MeDAB and OAT strongly inhibited glucocorticoid induction of TAT in the liver of susceptible but not resistant animals. DENA, which is highly carcinogenic for the liver of both rats and mice inhibited glucocorticoid induction of TAT in both species, while non-carcinogenic 4'-MeDAB was absolutely ineffective both in rats and mice. The inhibition of TAT activity by the carcinogens was due to reduced levels of TAT mRNA, which is most likely to be a result of the reduced rate of transcription initiation of the TAT gene. In all cases, the TAT inhibition was accompanied by significant reduction of DNA-binding activity of the HNF3 transcription factor, which is known to be critical to glucocorticoid regulation of TAT gene. We also demonstrated that the described species-specific effects of OAT and of 3'-MeDAB on HNF3 DNA-binding activity may be initiated not only by administration in vivo, but also by their direct administration to homogenate, intact nuclei or nuclear lysate, but not to nuclear extract fraction, obtained by precipitation with 0.32 g/mL of ammonium sulfate (Fraction I). We showed, that a factor responsible for this effect might be precipitated in 0.32-0.47 g/mL interval of ammonium sulfate concentration. In contrast, non-specific hepatocarcinogen DENA was effective upon being added directly to Fraction I, implying a different mechanism of its action.
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Affiliation(s)
- Tatyana I Merkulova
- Laboratory of Gene Expression Control, Institute of Cytology and Genetics of the Siberian Division of Russian Academy of Sciences, Novosibirsk, Russia
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Abstract
Mutations in the autoimmune regulator (AIRE) protein are the causative factor in development of the human disease autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). In mice, the absence of the analogous protein aire influences ectopic expression of peripheral tissue antigens in thymic medullary epithelial cells (MECs), resulting in the development of an autoimmune disorder similar to APECED and establishing aire/AIRE as an important player in the induction of central tolerance. However, the molecular mechanism of AIRE's function, in particular its ability to specifically control the expression of peripheral tissue antigens in MECs, is still unclear. Here, we review current evidence relating to the molecular mechanism of AIRE.
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Affiliation(s)
- Jennifer Villaseñor
- Department of Medicine, Section on Immunology and Immunogenetics, Joslin Diabetes Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02215, USA
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Purohit S, Kumar PG, Laloraya M, She JX. Mapping DNA-binding domains of the autoimmune regulator protein. Biochem Biophys Res Commun 2005; 327:939-44. [PMID: 15649436 DOI: 10.1016/j.bbrc.2004.12.093] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Indexed: 11/23/2022]
Abstract
The human autoimmune regulator (AIRE) gene encodes a putative DNA-binding protein, which is mutated in patients affected by the autoimmune polyglandular syndrome type 1 or autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy. We have recently reported that AIRE can bind to two different DNA sequence motifs, suggesting the existence of at least two DNA-binding domains in the AIRE protein. By expressing a series of recombinant AIRE protein fragments, we demonstrate here that the two well-known plant homeodomains (PHD) domains in AIRE can bind to the ATTGGTTA sequence motif. The first ATTGGTTA-binding domain is mapped to amino acids 299-355 and the second ATTGGTTA-binding domain to amino acids 434-475. Furthermore, the SAND domain of AIRE is shown to bind to TTATTA motif. Results presented herein show that the residues at position 189-196 of AIRE (QRAVAMSS) are required for its binding to the TTATTA motif. The required sequence for DNA binding in the SAND domain of AIRE is remarkably different from other SAND-containing proteins such as Sp-100b and NUDR. Data presented in this paper indicate that the two PHD domains contained in AIRE, in addition to the SAND domain, can bind to specific DNA sequence motifs.
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Affiliation(s)
- Sharad Purohit
- Center for Biotechnology and Genomic Medicine, Medical College of Georgia, CA4095, Augusta, GA 30912, USA
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Cho S, Kagan BL, Blackford JA, Szapary D, Simons SS. Glucocorticoid Receptor Ligand Binding Domain Is Sufficient for the Modulation of Glucocorticoid Induction Properties by Homologous Receptors, Coactivator Transcription Intermediary Factor 2, and Ubc9. Mol Endocrinol 2005; 19:290-311. [PMID: 15539428 DOI: 10.1210/me.2004-0134] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Several factors modulate the position of the dose-response curve of steroid receptor-agonist complexes and the partial agonist activity of antagonist complexes, thereby causing differential gene activation by circulating hormones and unequal gene repression during endocrine therapies with antisteroids. We now ask whether the modulatory activity of three factors (homologous receptor, coactivator transcription intermediary factor 2, and Ubc9) requires the same or different domains of glucocorticoid receptors (GRs). In all cases, we find that neither the amino terminal half of the receptor, which contains the activation function-1 activation domain, nor the DNA binding domain is required. This contrasts with the major role of activation function-1 in determining the amount of gene expression and partial agonist activity of antisteroids with most steroid receptors. However, the situation is more complicated with Ubc9, where GR N-terminal sequences prevent the actions of Ubc9, but not added GR or transcription intermediary factor 2, at low GR concentrations. Inhibition is relieved by deletion of these sequences or by replacement with the comparable region of progesterone receptors but not by overexpression of the repressive sequences. These results plus the binding of C-terminal GR sequences to the suppressive N-terminal domain implicate an intramolecular mechanism for the inhibition of Ubc9 actions at low GR concentrations. A shift from noncooperative to cooperative steroid binding at high GR concentrations suggests that conformational changes reposition the inhibitory N-terminal sequence to allow Ubc9 interaction with elements of the ligand binding domain. Collectively, these results indicate a dominant role of GR C-terminal sequences in the modulation of the dose-response curve and partial agonist activity of GR complexes. They also reveal mechanistic differences both among individual modulators and between the ability of the same factors to regulate the total amount of gene expression.
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Affiliation(s)
- Sehyung Cho
- Steriod Hormones Section, National Institute of Diabetes and Digestive and Kidney Diseases/LMCB, National Institutes of Health, Bethesda, Maryland 20892, USA
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Jensik PJ, Huggenvik JI, Collard MW. Identification of a nuclear export signal and protein interaction domains in deformed epidermal autoregulatory factor-1 (DEAF-1). J Biol Chem 2004; 279:32692-9. [PMID: 15161925 DOI: 10.1074/jbc.m400946200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Deformed epidermal autoregulatory factor-1 (DEAF-1) is a DNA-binding protein required for embryonic development and linked to clinical depression and suicidal behavior in humans. Although primarily nuclear, cytoplasmic localization of DEAF-1 has been observed, and this suggests the presence of a nuclear export signal (NES). Using a series of fluorescent fusion proteins, an NES with a novel spacing of leucines (LXLX(6)LLX(5)LX(2)L) was identified near the COOH-terminal MYND domain at amino acids 454-476. The NES was leptomycin B-sensitive and mutation of the leucine residues decreased or eliminated nuclear export activity. In vitro pull downs and an in vivo fluorescent protein interaction assay identified a DEAF-1/DEAF-1 protein interaction domain within the NES region. DNA binding had been previously mapped to a positively charged surface patch in the novel DNA binding fold called the "SAND" domain. A second protein-protein interaction domain was identified at amino acids 243-306 that contains the DNA-binding SAND domain and also an adjacent zinc binding motif and a monopartite nuclear localization signal (NLS). Deletion of these adjacent sequences or mutation of the conserved cysteines or histidine in the zinc binding motif not only inhibits protein interaction but also eliminates DNA binding, demonstrating that DEAF-1 protein-protein interaction is required for DNA recognition. The identification of an NES and NLS provides a basis for the control of DEAF-1 subcellular localization and function, whereas the requirement of protein-protein interaction by the SAND domain appears to be unique among this class of transcription factors.
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Affiliation(s)
- Philip J Jensik
- Department of Physiology, Southern Illinois University School of Medicine, Carbondale, Illinois 62901, USA
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Xing Y, Resch A, Lee C. The multiassembly problem: reconstructing multiple transcript isoforms from EST fragment mixtures. Genome Res 2004; 14:426-41. [PMID: 14962984 PMCID: PMC353230 DOI: 10.1101/gr.1304504] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2003] [Accepted: 12/01/2003] [Indexed: 12/28/2022]
Abstract
Recent evidence of abundant transcript variation (e.g., alternative splicing, alternative initiation, alternative polyadenylation) in complex genomes indicates that cataloging the complete set of transcripts from an organism is an important project. One challenge is the fact that most high-throughput experimental methods for characterizing transcripts (such as EST sequencing) give highly detailed information about short fragments of transcripts or protein products, instead of a complete characterization of a full-length form. We analyze this "multiassembly problem"-reconstructing the most likely set of full-length isoform sequences from a mixture of EST fragment data-and present a graph-based algorithm for solving it. In a variety of tests, we demonstrate that this algorithm deals appropriately with coupling of distinct alternative splicing events, increasing fragmentation of the input data and different types of transcript variation (such as alternative splicing, initiation, polyadenylation, and intron retention). To test the method's performance on pure fragment (EST) data, we removed all mRNA sequences, and found it produced no errors in 40 cases tested. Using this algorithm, we have constructed an Alternatively Spliced Proteins database (ASP) from analysis of human expressed and genomic sequences, consisting of 13,384 protein isoforms of 4422 genes, yielding an average of 3.0 protein isoforms per gene.
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Affiliation(s)
- Yi Xing
- UCLA-DOE Center for Genomics and Proteomics, Molecular Biology Institute and Department of Chemistry & Biochemistry, University of California, Los Angeles, Los Angeles, California 90095-1570, USA
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Chen J, He Y, Simons SS. Structure/Activity Relationships for GMEB-2: The Second Member of the Glucocorticoid Modulatory Element-Binding Complex. Biochemistry 2003; 43:245-55. [PMID: 14705952 DOI: 10.1021/bi035311b] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The position of the dose-response curve of agonist complexes of glucocorticoid receptors (GRs), and the partial agonist activity of GR-antagonist complexes, can be modulated by two proteins (GMEB-1 and -2), which bind as oligomers to a DNA element that is called a glucocorticoid modulatory element, or GME. This element is active when located upstream of the glucocorticoid response element that controls the expression of a reporter gene. Here, we report the structure/activity relationships of GMEB-2 and compare them to our previous findings for GMEB-1. Most of the activities of GMEB-2, such as homo- and heterooligomerization, binding to GR and to CBP, DNA binding, and modulation of the above GR transcriptional properties, require large regions of the protein. Only the intrinsic transactivation activity could be localized to a small region of the protein. These studies shed light on the mechanism of action of GMEB-2 and further support our previous conclusion that the ability of factors to modulate the position of the dose-response curve, and the partial agonist activity, of GR complexes is unrelated to effects on the total levels of GR-induced gene expression. These studies also identify regions of GMEB-2 possessing yet unidentified properties that are critical for several activities. Finally, as the domain organization of GMEB-2 and -1 is extremely similar, we conclude that the quantitative differences in activities derive from variations in amino acid sequence rather than more global features of protein structure.
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Affiliation(s)
- Jun Chen
- Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD, USA
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17
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Abstract
We recently reported that three factors (a cis-acting element and changing concentrations of receptor or coactivator TIF2) act at a common rate-limiting step to modulate the position of the dose-response curve and the partial agonist activity of glucocorticoid receptors (GRs). The ability of saturating levels of GR, and added inhibitors, to prevent the actions of the three modulators (cis-acting element, GR, and TIF2) but not the currently investigated C-terminal fragment of E1A-13S (E1A-133C) indicates that E1A-133C alters GR properties via a second pathway that is downstream of the common step for the original three modulators. hSur2 binds to E1A-133C. We find that hSur2 modulates GR transactivation properties, thus suggesting that the effects of E1A-133C are due to the recruitment of hSur2. hSur2 also modifies GR activities in the presence of saturating GR concentrations, which is consistent with hSur2 acting downstream of the common step for the original three modulators. The H160Y mutation, which eliminates hSur2 binding to E1A, blocks most of the activity of E1A-133C. This suggests that the modulatory activity of E1A-133C is largely due to the binding of hSur2, which is a component of the Mediator complex. Collectively, these data support the existence of a new pathway for modulating GR transactivation processes, thereby increasing the number of cellular mechanisms that permit differential control of gene expression by endogenous levels of glucocorticoid hormones.
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Affiliation(s)
- Shiyou Chen
- Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health (NIH), Building 8, Room B2A-07, Bethesda, MD 20892, USA
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18
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Grinkevich LN, Lisachev PD, Merkulova TI. Formation of AP-1 transcription factors during learning in Helix. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2003; 33:39-47. [PMID: 12617302 DOI: 10.1023/a:1021175230674] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Gel shift assays were used to study the formation of transcription factors of the AP-1 family in the CNS of Helix during the acquisition of a conditioned defensive reflex based on food aversion. Increases in the DNA-binding activity of AP-1 factors were seen 1-3 h after training. Modeling of "learning" in an in situ system (incubation of the CNS in the presence of serotonin and the Ca2+ ionophore A23187 or the protein kinase C activator phorbol ester (TPA)) also increased the DNA-binding activity of this transcription complex. The DNA-binding activity induced by serotonin acting alone was significantly less than that in controls, while that in the presence of A23187 and TPA was the same as or less than that in controls. The calcium/calmodulin-dependent protein kinase inhibitor KN62 produced significant suppression of the effects of simultaneous exposure to serotonin and calcium on the activation of transcription factors of the AP-1, while greater suppression was obtained with the mitogen-activated protein kinase (ERK) inhibitor PD98059. Cooperative induction of the activation of AP-1 transcription factors in the CNS of the common snail by the serotonin-induced and calcium-dependent regulatory systems may be a mechanism underlying the formation of conditioned defensive reflexes in these animals. Lesions of the formation of transcription factors of the AP-1 family in animals unable to learn defensive forms of behavioral plasticity may be explained in terms of the presence of inhibitory forms of transcription factors interacting with the SRE element.
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Affiliation(s)
- L N Grinkevich
- I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, 6 Makarov Bank, 199034 St. Petersburg, Russia
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19
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Chen J, Kaul S, Simons SS. Structure/activity elements of the multifunctional protein, GMEB-1. Characterization of domains relevant for the modulation of glucocorticoid receptor transactivation properties. J Biol Chem 2002; 277:22053-62. [PMID: 11934901 DOI: 10.1074/jbc.m202311200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
GMEB-1 was initially described as a component of a 550-kDa heteromeric DNA binding complex that is involved in the modulation of two properties of glucocorticoid receptor (GR) transactivation, the dose-response curve of agonists and the partial agonist activity of antagonists. Subsequently, GMEB-1 was also found to bind to hsp27, to associate with the coactivator TIF2 in yeast cells, and to participate in Parvovirus replication. To understand these multiple activities of GMEB-1 at a molecular level, we have now determined which regions are associated with the various activities associated with the modulation of GR transactivation properties. These activities include, homooligomerization, heterooligomerization, DNA binding, binding to GR and the transcriptional cofactor CBP, and GR modulation. Complex activities such as DNA binding and GR modulation, are found to require the physical combination of those domains that would be predicted from the involved biochemical processes. We have previously documented that GMEB-1 possesses both GR modulatory and intrinsic transactivation activity. However, the domains for these two activities of GMEB-1 are found not to overlap. This separation of activities provides a structural basis for our prior biological observations that the modulation of the dose-response curve and partial agonist activity of GR complexes is independent of the total levels of gene activation by the same GR complexes.
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Affiliation(s)
- Jun Chen
- Steroid Hormones Section, NIDDK/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, Maryland 20892
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20
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Veraksa A, Kennison J, McGinnis W. DEAF-1 function is essential for the early embryonic development of Drosophila. Genesis 2002; 33:67-76. [PMID: 12112874 DOI: 10.1002/gene.10090] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The Drosophila protein DEAF-1 is a sequence-specific DNA binding protein that was isolated as a putative cofactor of the Hox protein Deformed (Dfd). In this study, we analyze the effects of loss or gain of DEAF-1 function on Drosophila development. Maternal/zygotic mutations of DEAF-1 largely result in early embryonic arrest prior to the expression of zygotic segmentation genes, although a few embryos develop into larvae with segmentation defects of variable severity. Overexpression of DEAF-1 protein in embryos can induce defects in migration/closure of the dorsal epidermis, and overexpression in adult primordia can strongly disrupt the development of eye or wing. The DEAF-1 protein associates with many discrete sites on polytene chromosomes, suggesting that DEAF-1 is a rather general regulator of gene expression.
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Affiliation(s)
- Alexey Veraksa
- Division of Biology, University of California, San Diego, La Jolla, California 92093-0349, USA
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21
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Abel GA, Wochnik GM, Rüegg J, Rouyer A, Holsboer F, Rein T. Activity of the GR in G2 and mitosis. Mol Endocrinol 2002; 16:1352-66. [PMID: 12040020 DOI: 10.1210/mend.16.6.0842] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
To elucidate the mechanisms mediating the reported transient physiological glucocorticoid resistance in G2/M cell cycle phase, we sought to establish a model system of glucocorticoid-resistant cells in G2. We synchronized various cell lines in G2 to measure dexamethasone (DEX)-induced transactivation of either two endogenous promoters (rat tyrosine aminotransferase and mouse metallothionein I) or the mouse mammary tumor virus (MMTV) promoter stably or transiently transfected. To circumvent the need for synchronization drugs, we stably transfected an MMTV-driven green fluorescent protein to directly correlate DEX-induced transactivation with the cell cycle position for each cell of an asynchronous population using flow cytometry. Surprisingly, all promoters tested were DEX-inducible in G2. Even in mitotic cells, only the stably transfected MMTV promoter was repressed, whereas the same promoter transiently transfected was inducible. The use of Hoechst 33342 for synchronization in previous studies probably caused a misinterpretation, because we detected interference of this drug with GR-dependent transcription independent of the cell cycle. Finally, GR activated a simple promoter in G2, excluding a functional effect of cell cycle-dependent phosphorylation of GR, as implied previously. We conclude that GR itself is fully functional throughout the entire cell cycle, but GR responsiveness is repressed in mitosis due to chromatin condensation rather than to specific modification of GR.
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22
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Kaul S, Blackford JA, Cho S, Simons SS. Ubc9 is a novel modulator of the induction properties of glucocorticoid receptors. J Biol Chem 2002; 277:12541-9. [PMID: 11812797 DOI: 10.1074/jbc.m112330200] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The EC(50) of agonists and the partial agonist activity of antagonists are crucial parameters for steroid hormone control of gene expression and endocrine therapies. These parameters have been shown to be modulated by a naturally occurring cis-acting element, called the glucocorticoid modulatory element (GME) that binds two proteins, GMEB-1 and -2. We now present evidence that the GMEBs contact Ubc9, which is the mammalian homolog of a yeast E2 ubiquitin-conjugating enzyme. Ubc9 also binds to glucocorticoid receptors (GRs). Ubc9 displays no intrinsic transactivation activity but modifies both the absolute amount of induced gene product and the fold induction by GR. With high concentrations of GR, added Ubc9 also reduces the EC(50) of agonists and increases the partial agonist activity of antagonists in a manner that is independent of the ability of Ubc9 to transfer SUMO-1 (small ubiquitin-like modifier-1) to proteins. This new activity of Ubc9 requires only the ligand binding domain of GR and part of the hinge region. Interestingly, Ubc9 modulation of full-length GR transcriptional properties can be seen in the absence of a GME. This, though, is consistent with the GME acting by increasing the local concentration of Ubc9, which then activates a previously unobserved target in the transcriptional machinery. With high concentrations of Ubc9 and GR, Ubc9 binding to GR appears to be sufficient to permit Ubc9 to act independently of the GME.
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Affiliation(s)
- Sunil Kaul
- Steroid Hormones Section, NIDDK/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, MD 20892, USA
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23
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Grinkevich LN. Formation of C/EBP transcription factors and possible pathways for controlling their activity during learning in Helix. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2002; 32:33-9. [PMID: 11838553 DOI: 10.1023/a:1012944208122] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Formation of a conditioned defensive reflex in the common snail is accompanied by activation of DNA-binding transcription factors of the C/EBP family. Incubation of the CNS with serotonin, which imitates the effects of conditioning, and stimulation of adenylate cyclase with forskolin also increase the efficiency with which these transcription complexes are formed. Induction of protein kinase C with phorbol ester had no stimulating effect on the formation of C/EBP factors. However, simultaneous treatment with phorbol ester and serotonin produced some increase in the cAMP-inducible effects on the activation of C/EBP transcription factors. Larger increases in the DNA-binding activity of transcription factors of the C/EBP family in response to stimulation of the cAMP-dependent pathway were seen in conditions of elevated intracellular Ca2+ concentrations (by incubation of the CNS with the calcium ionophore A23187 and forskolin). Thus, it is possible that the Ca2+ and cAMP-dependent regulatory systems converge, leading to increases in the efficiency of the formation of C/EBP transcription complexes, which may reflect the interaction of stimuli of different modalities during learning.
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Affiliation(s)
- L N Grinkevich
- I. P. Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg
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24
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Burnett E, Christensen J, Tattersall P. A consensus DNA recognition motif for two KDWK transcription factors identifies flexible-length, CpG-methylation sensitive cognate binding sites in the majority of human promoters. J Mol Biol 2001; 314:1029-39. [PMID: 11743720 DOI: 10.1006/jmbi.2000.5198] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Parvovirus initiation factor (PIF), identified in HeLa cells as a host factor essential for parvoviral DNA replication, is a ubiquitous heterodimeric cellular transcription factor. This protein complex was simultaneously identified as glucocorticoid modulatory element binding protein (GMEB) by its ability to bind to the glucocorticoid modulating element (GME) upstream of the tyrosine transaminase promoter. Here, we show that the two PIF/GMEB subunits form site-specific DNA-binding heterodimers when co-expressed from recombinant baculoviruses and homodimers when expressed separately. Degenerate oligonucleotide selection experiments, combined with analysis of dissociation rates, established that the three complexes bind to flexibly spaced tetranucleotide half-sites that conform to the consensus ACGPy N(1-9) PuCGPy, with an optimum of N=6. Binding of all three complexes is extremely sensitive to methylation of the cytosine residues in the invariant CpG half-site core, suggesting a means by which PIF/GMEB binding could be regulated in vivo. Because CpG dinucleotides are suppressed in eukaryotic genomes, such binding sites would be expected to be very rare. However, analysis of 100 human promoters showed that over half of them contained at least one site conforming to the consensus, a significant deviation from the expected random distribution. In many of these, the binding site is within 100 nucleotides of the transcriptional start site, indicating that PIF/GMEB may be involved in regulation of these genes. Oligonucleotides corresponding to five of these sequences, chosen to represent the range of half-site separations identified by the consensus, were tested for PIF/GMEB binding by mobility shift assay. All five probes bound the heterodimer efficiently and, in each case, binding was completely abrogated by 5-methylation of the C residues in the CpGs of the putative half-sites.
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Affiliation(s)
- E Burnett
- Department of Genetics, Yale University School of Medicine, New Haven, CT 06510, USA
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25
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Christensen J, Cotmore SF, Tattersall P. Minute virus of mice initiator protein NS1 and a host KDWK family transcription factor must form a precise ternary complex with origin DNA for nicking to occur. J Virol 2001; 75:7009-17. [PMID: 11435581 PMCID: PMC114429 DOI: 10.1128/jvi.75.15.7009-7017.2001] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parvoviral rolling hairpin replication generates palindromic genomic concatemers whose junctions are resolved to give unit-length genomes by a process involving DNA replication initiated at origins derived from each viral telomere. The left-end origin of minute virus of mice (MVM), oriL, contains binding sites for the viral initiator nickase, NS1, and parvovirus initiation factor (PIF), a member of the emerging KDWK family of transcription factors. oriL is generated as an active form, oriL(TC), and as an inactive form, oriL(GAA), which contains a single additional nucleotide inserted between the NS1 and PIF sites. Here we examined the interactions on oriL(TC) which lead to activation of NS1 by PIF. The two subunits of PIF, p79 and p96, cooperatively bind two ACGT half-sites, which can be flexibly spaced. When coexpressed from recombinant baculoviruses, the PIF subunits preferentially form heterodimers which, in the presence of ATP, show cooperative binding with NS1 on oriL, but this interaction is preferentially enhanced on oriL(TC) compared to oriL(GAA). Without ATP, NS1 is unable to bind stably to its cognate site, but PIF facilitates this interaction, rendering the NS1 binding site, but not the nick site, resistant to DNase I. Varying the spacing of the PIF half-sites shows that the distance between the NS1 binding site and the NS1-proximal half-site is critical for nickase activation, whereas the position of the distal half-site is unimportant. When expressed separately, both PIF subunits form homodimers that bind site specifically to oriL, but only complexes containing p79 activate the NS1 nickase function.
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Affiliation(s)
- J Christensen
- Institute of Medical Microbiology and Immunology, University of Copenhagen, Panum Institute, Copenhagen 2200 N, Denmark
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26
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Tseng YT, Stabila JP, Nguyen TT, McGonnigal BG, Waschek JA, Padbury JF. A novel glucocorticoid regulatory unit mediates the hormone responsiveness of the beta1-adrenergic receptor gene. Mol Cell Endocrinol 2001; 181:165-78. [PMID: 11476950 DOI: 10.1016/s0303-7207(01)00490-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The effects of glucocorticoids on expression of the beta1-adrenergic receptor (beta1AR) gene have been varied. To study the mechanism underling hormonal regulation of the beta1AR, transient transfection of progressively deleted ovine beta1AR promoter fragments was used to identify a 43-bp region (-1274 to -1232 from the translation start site) that contains a novel glucocorticoid regulatory unit (GRU) and confers glucocorticoid responsiveness. Using DNase I footprinting and electrophoretic mobility shift assays (EMSA), we demonstrated the GRU was composed of a palindrome, 5'-TAATTA-3', which is a core binding motif for the homeodomain proteins, an E-box (5'-CACGTG-3'), binding site for the Myc/Max family proteins, and an overlapping glucocorticoid response element (GRE) half-site (5'-TGTTCT-3'). EMSA demonstrated that the GRE half-site is critical for GRU-protein interactions, which also require binding of proteins to the E-box and the homeodomain region. Co-transfection of a plasmid expressing a c-myc antisense construct significantly reduced glucocorticoid responsiveness of the ovine beta1AR promoter. Furthermore, expression of proteins binding to the GRU was shown to be developmentally regulated, being high in embryonic, reduced in newborn and not detectable in adult heart. We conclude that the ovine beta1AR promoter contains a novel, functional GRU and that glucocorticoid receptor (GR) and the Myc/Max family proteins are involved in the cell-specific nuclear factor binding and transactivation via this element. The results suggest an alternative pathway through which glucocorticoids may exert their effects on genes lacking a full consensus GRE.
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Affiliation(s)
- Y T Tseng
- Department of Pediatrics, Women and Infants Hospital of Rhode Island, Brown Medical School, Providence, RI 02905-2401, USA.
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27
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Kropachev KY, Kaledin VI, Kobzev VF, Plisov SY, Levashova ZB, Merkulova TI. Involvement of transcription factor HNF3gamma in the effect of o-aminoazotoluene on glucocorticoid induction of tyrosine aminotransferase in mice sensitive to its hepatocarcinogenic action. Mol Carcinog 2001; 31:10-5. [PMID: 11398193 DOI: 10.1002/mc.1035] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
In the rodent liver, hepatocarcinogens inhibit the glucocorticoid induction of several liver-specific genes, including tyrosine aminotransferase (TAT). A distinct positive correlation exists in mice between the extent of inhibition of TAT induction after acute administration of o-aminoazotoluene (OAT) and the frequency of liver tumors after chronic exposure to the carcinogen. To elucidate the mechanism of the carcinogenic action, the effects of OAT on the DNA-binding activity of several transcription factors participating in the glucocorticoid regulation of TAT gene expression were studied. The experimental inbred male mice were sensitive (A/He and SWR/J, tumor induction frequency of 75-100%, TAT induction inhibition of 35-50%) and resistant (CC57BR/Mv and AKR/J, 0-6% and 10-15%, respectively) to OAT. Gel retardation experiments showed that hepatocyte nuclear factor 3 (HNF3)gamma DNA-binding activity was strongly reduced in nuclear extracts from the livers of OAT-treated A/He and SWR/J mice but only slightly reduced in CC57Br/Mv and AKR/J mice. The DNA-binding activities of Ets, AP1 family members, and GME binding proteins were unaffected. HNF3gamma DNA-binding activity was reduced by 1 h after OAT administration and remained low for 1 mo, as did inhibition of TAT induction in the liver. These results suggested that the inhibitory effect of OAT on the glucocorticoid induction of TAT is mediated by reduced HNF3gamma DNA-binding activity.
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Affiliation(s)
- K Y Kropachev
- Laboratory of Gene Expression Control, Institute of Cytology and Genetics of the Siberian Division of the Russian Academy of Sciences, Novosibirsk, Russia
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28
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Chen S, Sarlis NJ, Simons SS. Evidence for a common step in three different processes for modulating the kinetic properties of glucocorticoid receptor-induced gene transcription. J Biol Chem 2000; 275:30106-17. [PMID: 10899170 DOI: 10.1074/jbc.m005418200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The dose-response curve of steroid hormones and the associated EC(50) value are critical parameters both in the development of new pharmacologically active compounds and in the endocrine therapy of various disease states. We have recently described three different variables that can reposition the dose-response curve of agonist-bound glucocorticoid receptors (GRs): a 21-base pair sequence of the rat tyrosine aminotransferase gene called a glucocorticoid modulatory element (GME), GR concentration, and coactivator concentration. At the same time, each of these three components was found to influence the partial agonist activity of antiglucocorticoids. In an effort to determine whether these three processes proceed via independent pathways or a common intermediate, we have examined several mechanistic details. The effects of increasing concentrations of both GR and the coactivator TIF2 are found to be saturable. Furthermore, saturating levels of either GR or TIF2 inhibit the ability of each protein, and the GME, to affect further changes in the dose-response curve or partial agonist activity of antisteroids. This competitive inhibition suggests that all three modulators proceed through a common step involving a titratable factor. Support for this hypothesis comes from the observation that a fragment of the coactivator TIF2 retaining intrinsic transactivation activity is a dominant negative inhibitor of each component (GME, GR, and coactivator). This inhibition was not due to nonspecific effects on the general transcription machinery as the VP16 transactivation domain was inactive. The viral protein E1A also prevented the action of each of the three components in a manner that was independent of E1A's ability to block the histone acetyltransferase activity of CBP. Collectively, these results suggest that three different inputs (GME, GR, and coactivator) for perturbing the dose-response curve, and partial agonist activity, of GR-steroid complexes act by converging at a single step that involves a limiting factor prior to transcription initiation.
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Affiliation(s)
- S Chen
- Steroid Hormones Section, NIDDK/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, Maryland 20892, USA
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29
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Kaul S, Blackford JA, Chen J, Ogryzko VV, Simons SS. Properties of the glucocorticoid modulatory element binding proteins GMEB-1 and -2: potential new modifiers of glucocorticoid receptor transactivation and members of the family of KDWK proteins. Mol Endocrinol 2000; 14:1010-27. [PMID: 10894151 DOI: 10.1210/mend.14.7.0494] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
An important component of glucocorticoid steroid induction of tyrosine aminotransferase (TAT) gene expression is the glucocorticoid modulatory element (GME), which is located at -3.6 kb of the rat TAT gene. The GME both mediates a greater sensitivity to hormone, due to a left shift in the dose-response curve of agonists, and increases the partial agonist activity of antiglucocorticoids. These properties of the GME are intimately related to the binding of a heteromeric complex of two proteins (GMEB-1 and -2). We previously cloned the rat GMEB-2 as a 67-kDa protein. We now report the cloning of the other member of the GME binding complex, the 88-kDa human GMEB-1, and various properties of both proteins. GMEB-1 and -2 each possess an intrinsic transactivation activity in mammalian one-hybrid assays, consistent with our proposed model in which they modify glucocorticoid receptor (GR)-regulated gene induction. This hypothesis is supported by interactions between GR and both GMEB-1 and -2 in mammalian two-hybrid and in pull-down assays. Furthermore, overexpression of GMEB-1 and -2, either alone or in combination, results in a reversible right shift in the dose-response curve, and decreased agonist activity of antisteroids, as expected from the squelching of other limiting factors. Additional mechanistic details that are compatible with the model of GME action are suggested by the interactions in a two-hybrid assay of both GMEBs with CREB-binding protein (CBP) and the absence of histone acetyl transferase (HAT) activity in both proteins. GMEB-1 and -2 share a sequence of 90 amino acids that is 80% identical. This region also displays homology to several other proteins containing a core sequence of KDWK. Thus, the GMEBs may be members of a new family of factors with interesting transcriptional properties.
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Affiliation(s)
- S Kaul
- Steroid Hormones Section, National Institute of Diabetes and Digestive and Kidney Diseases/Laboratory of Molecular and Cellular Biology, National Institutes of Health, Bethesda, Maryland 20892-0805, USA
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30
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Grinkevich LN, Vasil'ev GV. Possible molecular-cellular mechanisms of the regulation of gene expression during learning. NEUROSCIENCE AND BEHAVIORAL PHYSIOLOGY 2000; 30:277-92. [PMID: 10970022 DOI: 10.1007/bf02471781] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
This study is an analysis of the regulatory mechanisms of plasticity. The first part provides a short review of the role of DNA-binding transcription factors in possible regulatory pathways and their activity in the mechanisms of plasticity. Our own data obtained in studies of the molecular mechanisms underlying the formation of conditioned defensive reflexes in Helix are then presented. These studies show that formation of defensive types of plasticity in Helix is accompanied by serotonin-induced translocation of a protein with Rf 0.58 and increases in G-protein activity, protein kinase A activity, and expression of the c-fos gene. Transcription factors CRE and AP-1 probably have roles in the learning process. Gel shift assays demonstrated the existence of transcription factors of the CRE and AP-1 families in adult snails. In juvenile snails, which were unable to form defensive types of plasticity, the serotonin protein with Rf 0.58 (the learning "marker") was absent from and was not induced in the CNS. Gel shift assay results also showed that transcription factors of the AP-1 family were not present and were not induced by serotonin or the protein kinase A activator forskolin, though these snails had significant levels of CRE transcription factors. Serotonin and forskolin increased the DNA-binding activity of CRE in juvenile Helix. The lack of activity of transcription factors of the AP-1 family in juvenile snails may explain their inability to development sensitization and conditioned defensive reflexes.
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Affiliation(s)
- L N Grinkevich
- IP Pavlov Institute of Physiology, Russian Academy of Sciences, St Petersburg
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31
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Zeng H, Plisov SY, Simons SS. Ability of the glucocorticoid modulatory element to modify glucocorticoid receptor transactivation indicates parallel pathways for the expression of glucocorticoid modulatory element and glucocorticoid response element activities. Mol Cell Endocrinol 2000; 162:221-34. [PMID: 10854715 DOI: 10.1016/s0303-7207(99)00208-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The glucocorticoid modulatory element (GME) of the rat tyrosine aminotransferase gene is located at -3.6 kb and 1 kb upstream of the glucocorticoid response elements (GREs). The GME has the unique transcriptional properties of modulating both the dose-response curve of agonists bound to the glucocorticoid receptor (GR) and the residual agonist activity of GR-bound antisteroids. The expression of GME activity involves the binding of two novel proteins (GMEB-1 and GMEB-2) that we have recently cloned. However, the mechanistic details are limited. The DNA sequence requirements for GME activity (CGTC) also remain poorly defined, which restricts efforts to identify other GME modulated genes. To help understand the mechanism for the unusual activities of the GME and to identify permissive gene environments for GME activity, we compared the changes in GME activity and GRE action (i.e. the fold induction by GR) caused by modifying several parameters. Phasing between the GME and downstream tandem GREs was unimportant, in contrast to other cis-acting elements like the GRE, while GME activity decreased rapidly when placed at increasingly larger distances 3' to a tandem GRE. A minimal promoter was less effective in supporting GME than GRE activity. Although CREB binds to the GME, overexpression of CREB reduced GRE, but not GME, activity and a CRE was inactive when substituted for the GME. No effect of the GME was observed on the binding of GRs to a single GRE. However, the GME upstream of a single GRE was also unable to produce a left shift in the Dex dose-response curve under conditions where the GME was active with two GREs. In the absence of any GREs, the GME displayed intrinsic activity by elevating basal level expression. Collectively, these results indicate that an optimal position for a functional GME is within 250 bp upstream of a tandem GRE driving a complex promoter. Furthermore, as the changes in GME activity did not correlate with those for fold induction from the GRE, the mechanisms for expression of GME and GRE activities appear to utilize parallel, as opposed to common pathways.
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MESH Headings
- Animals
- Base Sequence
- Binding Sites/genetics
- Binding, Competitive
- Cyclic AMP Response Element-Binding Protein/metabolism
- DNA Primers/genetics
- DNA, Neoplasm/genetics
- DNA, Neoplasm/metabolism
- Liver Neoplasms, Experimental/genetics
- Liver Neoplasms, Experimental/metabolism
- Models, Biological
- Promoter Regions, Genetic
- Rats
- Receptors, Glucocorticoid/agonists
- Receptors, Glucocorticoid/genetics
- Transcriptional Activation
- Transfection
- Tumor Cells, Cultured
- Tyrosine Transaminase/genetics
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Affiliation(s)
- H Zeng
- The Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health, Bethesda, MD 20892, USA
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Zeng H, Kaul S, Simons SS. Genomic organization of human GMEB-1 and rat GMEB-2: structural conservation of two multifunctional proteins. Nucleic Acids Res 2000; 28:1819-29. [PMID: 10734202 PMCID: PMC102812 DOI: 10.1093/nar/28.8.1819] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The glucocorticoid modulatory element binding proteins 1 and 2 (GMEB-1 and GMEB-2) are of interest both for their multiple activities (e.g. modulation of transactivation by the glucocorticoid receptor and initiation of parvovirus replication) and their membership in the emerging family of KDWK proteins. The genomic sequence of these proteins was desired in order to begin studies on the control of GMEB expression and to pursue previous evidence for significant homologies between the GMEBs. We now report the genomic sequence of human GMEB-1 and rat GMEB-2. The structure of both genes, including portions of the introns, is highly conserved. However, GMEB-1 and GMEB-2 were found to reside on chromosomes 1 and 20, respectively, demonstrating that they are encoded by distinctly different genes. Several isoforms of the GMEBs have been reported or detected in this study, and the splicing patterns were determined. The tissue distribution of each GMEB is not the same and is highest in fetal and developing tissues, consistent with previous suggestions that both homo- and hetero-oligomers may possess biological activity. The promoter region of both genes has been identified and both display high levels of transcription activity in transiently transfected cells when fused upstream of a promoterless reporter. These results indicate that the GMEBs are proteins that evolved from a single parent gene, have been highly conserved since the divergence of rats and humans and probably play important roles in development and differentiation.
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Affiliation(s)
- H Zeng
- Steroid Hormones Section, Building 8, Room B2A-07, NIDDK/LMCB, National Institutes of Health, Bethesda, MD 20892, USA
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Jimenez-Lara AM, Heine MJ, Gronemeyer H. Cloning of a mouse glucocorticoid modulatory element binding protein, a new member of the KDWK family. FEBS Lett 2000; 468:203-10. [PMID: 10692587 DOI: 10.1016/s0014-5793(00)01209-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A mouse cDNA that encodes a nuclear DNA binding protein was identified by yeast two-hybrid screening using the activation domain 2 of the nuclear receptor coactivator TIF2 as a bait. BLAST analysis revealed that the identified cDNA encodes a KDWK domain and contains sequences almost identical to three tryptic peptides of rat GMEB-1 which together with the GMEB-2 heterodimeric partner binds to the GME/CRE sequence (glucocorticoid modulatory element) of the tyrosine aminotransferase (TAT) promoter. Mouse GMEB-1 is ubiquitously expressed in all the tissues examined. In vitro translated mGMEB-1 bound specifically to GME oligonucleotides, either alone or as a heterodimer with rGMEB-2. Transient transfection experiments with TAT promoter reporter genes suggest a potential role for mGMEB-1 as a transcriptional regulator of the TAT promoter.
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Affiliation(s)
- A M Jimenez-Lara
- Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, P.O. Box 163, 67404, Illkirch, France
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Christensen J, Cotmore SF, Tattersall P. Two new members of the emerging KDWK family of combinatorial transcription modulators bind as a heterodimer to flexibly spaced PuCGPy half-sites. Mol Cell Biol 1999; 19:7741-50. [PMID: 10523663 PMCID: PMC84824 DOI: 10.1128/mcb.19.11.7741] [Citation(s) in RCA: 29] [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
Initially recognized as a HeLa factor essential for parvovirus DNA replication, parvovirus initiation factor (PIF) is a site-specific DNA-binding complex consisting of p96 and p79 subunits. We have cloned and sequenced the human cDNAs encoding each subunit and characterized their products expressed from recombinant baculoviruses. The p96 and p79 polypeptides have 40% amino acid identity, focused particularly within a 94-residue region containing the sequence KDWK. This motif, first described for the Drosophila homeobox activator DEAF-1, identifies an emerging group of metazoan transcriptional modulators. During viral replication, PIF critically regulates the viral nickase, but in the host cell it probably modulates transcription, since each subunit is active in promoter activation assays and the complex binds to previously described regulatory elements in the tyrosine aminotransferase and transferrin receptor promoters. Within its recognition site, PIF binds coordinately to two copies of the tetranucleotide PuCGPy, which, remarkably, can be spaced from 1 to 15 nucleotides apart, a novel flexibility that we suggest may be characteristic of the KDWK family. Such tetranucleotides are common in promoter regions, particularly in activating transcription factor/cyclic AMP response element-binding protein (ATF/CREB) and E-box motifs, suggesting that PIF may modulate the transcription of many genes.
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Affiliation(s)
- J Christensen
- Department of Laboratory Medicine, Yale University School of Medicine, New Haven, Connecticut 06510, USA
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35
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Thériault JR, Charette SJ, Lambert H, Landry J. Cloning and characterization of hGMEB1, a novel glucocorticoid modulatory element binding protein. FEBS Lett 1999; 452:170-6. [PMID: 10386584 DOI: 10.1016/s0014-5793(99)00634-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A 21-bp element called glucocorticoid modulatory element (GME) modulates the glucocorticoid receptor-mediated responses via the binding of an as yet poorly characterized transacting complex of proteins containing the 88-kDa GMEB1 and the 67-kDa GMEB2. Using heat shock protein 27 (HSP27) as bait in the yeast two-hybrid assay, we cloned a 1.83-kb cDNA encoding a novel 573-amino acid protein called human GMEB1 (hGMEB1). hGMEB1 possesses a KDWK domain, contains sequences almost identical (36/38) to three tryptic peptides of rat GMEB1 and shares 38% identity with rat GMEB2. hGMEB1 is ubiquitously expressed as a 85-kDa protein in all cell lines and tissues examined. In vitro translated hGMEB1 bound specifically to GME oligonucleotides yielding a complex of similar size to the complex obtained using rat liver nuclear extracts. Both complexes were supershifted with an antibody specific to hGMEB1. Co-immunoprecipitation experiments confirmed the in vivo interaction of HSP27 with hGMEB1.
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Affiliation(s)
- J R Thériault
- Centre de recherche en cancérologie de l'Université Laval, L'Hôtel-Dieu de Québec, Que., Canada
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36
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Montano MM, Jaiswal AK, Katzenellenbogen BS. Transcriptional regulation of the human quinone reductase gene by antiestrogen-liganded estrogen receptor-alpha and estrogen receptor-beta. J Biol Chem 1998; 273:25443-9. [PMID: 9738013 DOI: 10.1074/jbc.273.39.25443] [Citation(s) in RCA: 96] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have previously reported that antiestrogens stimulate quinone reductase (NAD(P)H:(quinone-acceptor) oxidoreductase (QR or NQO1); EC 1.6.99.2) enzymatic activity, an action that may provide protective effects against the toxicity and mutagenicity caused by quinones. We have now investigated the transcriptional regulation of the QR gene by antiestrogens. In transfection experiments employing the 5'-flanking (863-base pair) region of the human QR gene promoter with its electrophile/antioxidant response element (EpRE/ARE) or deleted or mutated constructs, we observe that antiestrogens induced an increase in QR gene promoter reporter activity in estrogen receptor (ER) negative breast cancer and endometrial cancer cells transfected with ER, and this induction by antiestrogens was repressed by estradiol. The stimulation of QR transcriptional activity required the 31-base pair electrophile-responsive region from the human QR gene promoter and a functional ER. Intriguingly, antiestrogens were stronger activators of the QR EpRE via the ER subtype ERbeta than ERalpha. Oligonucleotide gel mobility and antibody shift assays reveal that the ER binds to the EpRE but is only a minor component of the proteins bound to the EpRE in ER-containing MCF-7 breast cancer cells. While binding of ERbeta to the estrogen response element was weaker when compared with ERalpha, ERbeta and ERalpha showed similar binding to the EpRE. Together these findings provide evidence that QR gene regulation by the antiestrogen-occupied ER is mediated by the EpRE-containing region of the human QR gene and indicate that the ER is one of the complex of proteins that binds to the EpRE. In addition, that ERbeta is a more potent activator at EpRE elements than is ERalpha suggests that the different levels of these two receptors in various estrogen target cells could impact importantly on the antioxidant potency of antiestrogens in different target cells. These findings have broad implications regarding the potential beneficial effects of antiestrogens since EpREs mediate the transcriptional induction of numerous genes, including QR, which encode chemoprotective detoxification enzymes.
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Affiliation(s)
- M M Montano
- Departments of Molecular and Integrative Physiology, Cell and Structural Biology, University of Illinois and College of Medicine, Urbana, Illinois 61801-3704, USA
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Jackson DA, Collier CD, Oshima H, Simons SS. Modulation of TAT gene induction by glucocorticoids involves a neutralizing sequence. J Steroid Biochem Mol Biol 1998; 66:79-91. [PMID: 9719442 DOI: 10.1016/s0960-0760(98)00048-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Recent studies have indicated that two elements in addition to the glucocorticoid response element (GRE) are involved in the induction of the endogenous TAT gene in FuS-5 rat hepatoma cells. The first is the 21 bp glucocorticoid modulatory element (GME) at -3648 bp, which causes reporter constructs to display both a left shift in the dose-response curve for glucocorticoids and increased percentages of agonist activity for antiglucocorticoids. The second is a negative element at -3340 to -3050 that blocks the action of the GME. This last observation raised the question of how GME activity can be expressed in Fu5-5 cells in the intact TAT gene that contains both the GME and the negative element. The present study identifies a third element, a "neutralizing" sequence, that restores the activity of the GME even when otherwise inactivated by the negative element. This neutralizing sequence was located within the region surrounding the GREs of the TAT gene but is separate from the GREs. The activity of the individual GME and negative elements was found to depend upon spacing. However, in combination with the natural GRE, the native TAT gene spacing of the GME and negative elements was able to reproduce the activity of the intact gene. Thus, a total of three additional elements (an activator, a negative element, and a neutralizer) appear to cooperate with the GREs in glucocorticoid induction of the TAT gene in Fu5-5 cells. While such a grouping of elements may be novel among steroid regulated genes, it is a not uncommon occurrence for the transcriptional control of other genes.
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Affiliation(s)
- D A Jackson
- Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health, Bethesda, MD 20892, USA.
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38
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Zeng H, Jackson DA, Oshima H, Simons SS. Cloning and characterization of a novel binding factor (GMEB-2) of the glucocorticoid modulatory element. J Biol Chem 1998; 273:17756-62. [PMID: 9651376 DOI: 10.1074/jbc.273.28.17756] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 21-base pair glucocorticoid modulatory element (GME) of the rat tyrosine aminotransferase gene is the only cis-acting element known to modulate the transcriptional activity of receptors bound to glucocorticoid response elements. Specifically, the GME increases the activity of complexes bound both by physiological concentrations of glucocorticoids, due to a left shift in the dose-response curve, and by saturating concentrations of anti-glucocorticoids. For this reason, the nuclear protein(s) that has been demonstrated to bind to the GME is of major interest as a possible transcription factor with hitherto undescribed properties. Subsequent studies indicated that not one but two proteins of 88 and 67 kDa (= GMEB-1 and -2, respectively) formed a heteromeric complex with double-stranded GME oligonucleotides in gel shift assays and participated in the expression of GME activity (Oshima, H., Szapary, D., and Simons, S. S., Jr. (1995) J. Biol. Chem. 270, 21893-21910). Here, we report the use of polymerase chain reaction of degenerate oligonucleotides and 5'- and 3'-rapid amplification of cDNA ends to clone two cDNAs of 2. 0 and 1.9 kilobase pairs that probably result from alternative splicing. Both cDNAs encoded open reading frames containing all four previously sequenced peptides. The longer 2.0-kilobase pair cDNA encoded an open reading frame for an acidic, 529-amino acid protein and afforded a major 67-kDa and a minor 58-kDa protein after in vitro transcription/translation. Both proteins were recognized by a mono-epitopic antibody raised against a peptide of GMEB-2. The in vitro translated protein bound to GME DNA in gel shift assays. However, the binding to GME DNA increased markedly after mixing with authentic GMEB-1 to give a gel-shifted complex that was similar to that derived from HTC cell cytosol. GMEB-2 shares a unique domain (KDWKR) with proteins derived from diverse organisms as follows: Drosophila (DEAF-I), rat (Suppressin), and Caenorhabditis elegans (three unknown open reading frames). Collectively, these data suggest that the 67-kDa GMEB-2 not only is an important factor for the modulation of glucocorticoid receptor bound to glucocorticoid response elements but also may belong to a novel family of transcription factors.
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Affiliation(s)
- H Zeng
- Steroid Hormones Section, NIDDK/LMCB, National Institutes of Health, Bethesda, Maryland 20892, USA
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