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Ruggiero C, Lalli E. Impact of ACTH Signaling on Transcriptional Regulation of Steroidogenic Genes. Front Endocrinol (Lausanne) 2016; 7:24. [PMID: 27065945 PMCID: PMC4810002 DOI: 10.3389/fendo.2016.00024] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/14/2016] [Indexed: 01/12/2023] Open
Abstract
The trophic peptide hormone adrenocorticotropic (ACTH) stimulates steroid hormone biosynthesis evoking both a rapid, acute response and a long-term, chronic response, via the activation of cAMP/protein kinase A (PKA) signaling. The acute response is initiated by the mobilization of cholesterol from lipid stores and its delivery to the inner mitochondrial membrane, a process that is mediated by the steroidogenic acute regulatory protein. The chronic response results in the increased coordinated transcription of genes encoding steroidogenic enzymes. ACTH binding to its cognate receptor, melanocortin 2 receptor (MC2R), stimulates adenylyl cyclase, thus inducing cAMP production, PKA activation, and phosphorylation of specific nuclear factors, which bind to target promoters and facilitate coactivator protein recruitment to direct steroidogenic gene transcription. This review provides a general view of the transcriptional control exerted by the ACTH/cAMP system on the expression of genes encoding for steroidogenic enzymes in the adrenal cortex. Special emphasis will be given to the transcription factors required to mediate ACTH-dependent transcription of steroidogenic genes.
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Affiliation(s)
- Carmen Ruggiero
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 7275, Valbonne, France
- Laboratoire International Associé (LIA) CNRS NEOGENEX, Valbonne, France
- Université de Nice, Valbonne, France
- *Correspondence: Carmen Ruggiero, ; Enzo Lalli,
| | - Enzo Lalli
- Institut de Pharmacologie Moléculaire et Cellulaire CNRS UMR 7275, Valbonne, France
- Laboratoire International Associé (LIA) CNRS NEOGENEX, Valbonne, France
- Université de Nice, Valbonne, France
- *Correspondence: Carmen Ruggiero, ; Enzo Lalli,
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2
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Manna PR, Dyson MT, Stocco DM. Role of basic leucine zipper proteins in transcriptional regulation of the steroidogenic acute regulatory protein gene. Mol Cell Endocrinol 2009; 302:1-11. [PMID: 19150388 PMCID: PMC5006949 DOI: 10.1016/j.mce.2008.12.009] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 12/15/2008] [Accepted: 12/15/2008] [Indexed: 01/23/2023]
Abstract
The regulation of steroidogenic acute regulatory protein (StAR) gene transcription by cAMP-dependent mechanisms occurs in the absence of a consensus cAMP response element (CRE, TGACGTGA). This regulation is coordinated by multiple transcription factors that bind to sequence-specific elements located approximately 150 bp upstream of the transcription start site. Among the proteins that bind within this region, the basic leucine zipper (bZIP) family of transcription factors, i.e. CRE binding protein (CREB)/CRE modulator (CREM)/activating transcription factor (ATF), activator protein 1 (AP-1; Fos/Jun), and CCAAT enhancer binding protein beta (C/EBPbeta), interact with an overlapping region (-81/-72 bp) in the StAR promoter, mediate stimulus-transcription coupling of cAMP signaling and play integral roles in regulating StAR gene expression. These bZIP proteins are structurally similar and bind to DNA sequences as dimers; however, they exhibit discrete transcriptional activities, interact with several transcription factors and other properties that contribute in their regulatory functions. The 5'-flanking -81/-72 bp region of the StAR gene appears to function as a key element within a complex cAMP response unit by binding to different bZIP members, and the StAR promoter displays variable states of cAMP responsivity contingent upon the occupancy of these cis-elements with these transcription factors. The expression and activities of CREB/CREM/ATF, Fos/Jun and C/EBPbeta have been demonstrated to be mediated by a plethora of extracellular signals, and the phosphorylation of these proteins at several Ser and Thr residues allows recruitment of the transcriptional coactivator CREB binding protein (CBP) or its functional homolog p300 to the StAR promoter. This review will focus on the current level of understanding of the roles of selective bZIP family proteins within the complex series of processes involved in regulating StAR gene transcription.
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Affiliation(s)
- Pulak R Manna
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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3
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Zubenko GS, Jones ML, Estevez AO, Hughes HB, Estevez M. Identification of a CREB-dependent serotonergic pathway and neuronal circuit regulating foraging behavior in Caenorhabditis elegans: a useful model for mental disorders and their treatments? Am J Med Genet B Neuropsychiatr Genet 2009; 150B:12-23. [PMID: 19035344 PMCID: PMC3234207 DOI: 10.1002/ajmg.b.30891] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The cAMP-response element binding protein (CREB)-mediated cell signaling pathway is conserved through evolution and participates in a broad range of complex behaviors of divergent species including man. This study describes the integration of genetic, pharmacologic, and anatomic methods to elucidate a serotonergic signaling pathway by which the CREB homolog CRH-1 controls foraging rate (FR) in the model organism Caenorhabditis elegans, along with the complete neuronal circuit through which this pathway operates. In the anterior afferent arm of the circuit, CRH-1 controls FR by regulating the expression of tph-1, the sole structural gene for tryptophan hydroxylase, in serotonergic sensory (ADF) neurons whose post-synaptic effects are mediated through 5HT(2)-like SER-1 receptors. The posterior afferent limb of the circuit includes an interneuron (RIH) that does not express tph-1 and whose serotonergic phenotype is dependent on the contribution of this neurotransmitter from another source, probably the ADF neurons. The postsynaptic effects of the RIH interneuron are mediated through 5HT(1)-like SER-4 receptors. This model has potential utility for the study of clinical disorders and experimental therapeutics. Furthermore, the discovery of serotonergic neurons that depend on other sources for their neurotransmitter phenotype could provide a mechanism for rapidly altering the number and distribution of serotonergic pathways in developing and adult nervous systems, providing a dimension of functional complexity that has been previously unrecognized.
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Affiliation(s)
- George S. Zubenko
- Department of Psychiatry University of Pittsburgh School of Medicine, Pittsburgh, PA,Department of Biological Sciences, Mellon College of Science, Carnegie-Mellon University, Pittsburgh, PA
| | - Michelle L. Jones
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Annette O. Estevez
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Hugh B. Hughes
- Department of Psychiatry University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Miguel Estevez
- Department of Neurology, University of Pittsburgh School of Medicine, Pittsburgh, PA,Department of Veteran's Affairs Medical Center, Pittsburgh, PA
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4
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Fenton MS, Marion KM, Hershman JM. Identification of cyclic adenosine 3',5'-monophosphate response element modulator as an activator of the human sodium/iodide symporter upstream enhancer. Endocrinology 2008; 149:2592-606. [PMID: 18202121 PMCID: PMC2329265 DOI: 10.1210/en.2007-1390] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The lack of Na(+)/I(-) symporter (NIS) gene expression in some thyroid cancer patients has been a major hurdle that limits the efficacy of standard radioactive iodide therapy. The molecular mechanism that contributes to low NIS expression is not well understood. Activated NIS gene expression is stimulated by thyroid-stimulating hormone-mediated cAMP/protein kinase A signaling through a NIS upstream enhancer (NUE). The cAMP pathway is also stimulated by forskolin. In the current work, we studied the mechanism of transcriptional activation of NIS in normal thyroid cells and thyroid cancer cells. We identified the cAMP response element modulator (CREM) activator as a new component of the transcription complex that is important for NIS gene expression. The CREM complex is seen in the normal thyroid cells and BRAF (V600E) thyroid cancer cells (BHP 17-10) but is missing in rearranged in transformation/papillary thyroid carcinoma-1 rearrangement thyroid cancer cells (BHP 2-7). This complex is believed to be responsible for the loss of NUE activity and reduced NIS expression in the BHP 2-7 cell line. In BHP 2-7 cells, forskolin stimulated the thyroid-specific transcription factor Pax 8, but CREM activator mRNA did not increase, and this produced a small increase in NUE activity. Ectopic expression of CREM activator enhanced activity of the NUE, indicating that CREM is an essential regulator of NIS gene expression.
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Affiliation(s)
- Mike S Fenton
- Endocrinology Division, Veterans Affairs Greater Los Angeles Healthcare System and Department of Medicine, University of California Los Angeles School of Medicine, Los Angeles, California 90073, USA.
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Kimura Y, Corcoran EE, Eto K, Gengyo-Ando K, Muramatsu MA, Kobayashi R, Freedman JH, Mitani S, Hagiwara M, Means AR, Tokumitsu H. A CaMK cascade activates CRE-mediated transcription in neurons of Caenorhabditis elegans. EMBO Rep 2002; 3:962-6. [PMID: 12231504 PMCID: PMC1307624 DOI: 10.1093/embo-reports/kvf191] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2002] [Revised: 07/01/2002] [Accepted: 07/25/2002] [Indexed: 11/15/2022] Open
Abstract
Calcium (Ca2+) signals regulate a diverse set of cellular responses, from proliferation to muscular contraction and neuro-endocrine secretion. The ubiquitous Ca2+ sensor, calmodulin (CaM), translates changes in local intracellular Ca2+ concentrations into changes in enzyme activities. Among its targets, the Ca2+/CaM-dependent protein kinases I and IV (CaMKs) are capable of transducing intraneuronal signals, and these kinases are implicated in neuronal gene regulation that mediates synaptic plasticity in mammals. Recently, the cyclic AMP response element binding protein (CREB) has been proposed as a target for a CaMK cascade involving not only CaMKI or CaMKIV, but also an upstream kinase kinase that is also CaM regulated (CaMKK). Here, we report that all components of this pathway are coexpressed in head neurons of Caenorhabditis elegans. Utilizing a transgenic approach to visualize CREB-dependent transcription in vivo, we show that this CaMK cascade regulates CRE-mediated transcription in a subset of head neurons in living nematodes.
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Affiliation(s)
- Yoshishige Kimura
- Department of Functional Genomics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510
| | - Ethan E. Corcoran
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27710, USA
| | - Koh Eto
- Division of Molecular Genetics, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo 187-8551
| | - Keiko Gengyo-Ando
- Department of Physiology, Tokyo Women's Medical University, Tokyo 162-8666
| | - Masa-aki Muramatsu
- Department of Molecular Epidemiology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 101-0062
| | - Ryoji Kobayashi
- Department of Chemistry, Kagawa Medical University, Kagawa 761-0701, Japan
| | - Jonathan H. Freedman
- Department of Molecular Toxicology, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27710, USA
| | - Shohei Mitani
- Department of Physiology, Tokyo Women's Medical University, Tokyo 162-8666
| | - Masatoshi Hagiwara
- Department of Functional Genomics, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510
| | - Anthony R. Means
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Nicholas School of the Environment and Earth Sciences, Duke University, Durham, NC 27710, USA
| | - Hiroshi Tokumitsu
- Department of Chemistry, Kagawa Medical University, Kagawa 761-0701, Japan
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Grundschober C, Malosio ML, Astolfi L, Giordano T, Nef P, Meldolesi J. Neurosecretion competence. A comprehensive gene expression program identified in PC12 cells. J Biol Chem 2002; 277:36715-24. [PMID: 12070162 DOI: 10.1074/jbc.m203777200] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The phenotype of neurosecretory cells is characterized by clear vesicles and dense granules, both discharged by regulated exocytosis. However, these organelles are lacking completely in a few neurosecretion-incompetent clones of the pheochromocytoma PC12 line, in which other specific features are maintained (incompetent clones). In view of the heterogeneity of PC12 cells, a differential characterization of the incompetent phenotype based on the comparison of a single incompetent and a single wild-type clone would have been inconclusive. Therefore, we have compared two pairs of PC12 clones, studying in parallel the transcript levels of 4,200 genes and 19,000 express sequence tags (ESTs) by high density oligonucleotide arrays. After accurate data processing for quality control and filtration, a total of 755 transcripts, corresponding to 448 genes and 307 ESTs, was found consistently changed, with 46% up-regulated and 54% down-regulated in incompetent versus wild-type clones. Many but not all neurosecretion genes were profoundly down-regulated in incompetent cells. Expression of endocytosis genes was normal, whereas that of many nuclear and transcription factors, including some previously shown to play key roles in neurogenesis, was profoundly changed. Additional differences appeared in genes involved in signaling and metabolism. Taken together these results demonstrate for the first time that expression of neurosecretory vesicles and granules is part of a complex gene expression program that includes many other features that so far have not been recognized.
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Affiliation(s)
- Christophe Grundschober
- Central Nervous System, F. Hoffmann-La Roche Ltd., Grenzacherstrasse, Basel 4070, Switzerland
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Inada A, Someya Y, Yamada Y, Ihara Y, Kubota A, Ban N, Watanabe R, Tsuda K, Seino Y. The cyclic AMP response element modulator family regulates the insulin gene transcription by interacting with transcription factor IID. J Biol Chem 1999; 274:21095-103. [PMID: 10409662 DOI: 10.1074/jbc.274.30.21095] [Citation(s) in RCA: 37] [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
We analyzed a mechanism of transcriptional regulation of the human insulin gene by cyclic AMP response element modulator (CREM) through four cyclic AMP response elements (CREs). We isolated two novel CREM isoforms (CREMDeltaQ1 and CREMDeltaQ2), which lack one of the glutamine-rich domains, Q1 and Q2 respectively, and six known isoforms (CREMtaualpha, CREMalpha, inducible cyclic AMP early repressor (ICER) I, ICER Igamma, CREM-17X, and CREM-17) from rat pancreatic islets and the RINm5F pancreatic beta-cell line. CREM isoforms functioned as efficient transcriptional activators or repressors to modulate insulin promoter activity by binding to all of the insulin CREs. The binding activity of repressors is higher than that of activators and suppressed not only basal activity but also activator-induced activities. Furthermore, CREM activator interacted directly with the transcription factor IID components hTAF(II)130 and TATA box-binding protein (TBP). These results suggest that the activation of the insulin gene transcription by CREM activator is mediated by not only direct binding to the CREs but also by recruiting transcription factor IID to the insulin promoter via its interaction with hTAF(II)130 and TBP. On the other hand, the CREM repressor ICER competitively interrupts the binding of the activators to CREs and does not interact with either TBP or hTAF(II)130; therefore, it might fail to stabilize the basal transcriptional machinery and repress transactivation.
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Affiliation(s)
- A Inada
- Department of Metabolism and Clinical Nutrition, Graduate School of Medicine, Kyoto University, Kyoto, Japan 606-8507, USA.
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8
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Inada A, Yamada Y, Someya Y, Kubota A, Yasuda K, Ihara Y, Kagimoto S, Kuroe A, Tsuda K, Seino Y. Transcriptional repressors are increased in pancreatic islets of type 2 diabetic rats. Biochem Biophys Res Commun 1998; 253:712-8. [PMID: 9918792 DOI: 10.1006/bbrc.1998.9833] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To further clarify the mechanism of impaired insulin gene transcription in the diabetic state, we investigated the expression and function of the transcriptional repressor CREM (CRE modulator) in rat pancreatic islets. The CREM gene generates both transcriptional activators and repressors by alternative splicing and an intronic promoter. We isolated a novel alternatively spliced CREM isoform, CREM-17X, which efficiently represses insulin gene transcription, in addition to the three previously reported repressors. We also compared mRNA levels of insulin and the CREM repressors in pancreatic islets of Wistar and GK (Goto-Kakizaki) rats, the well-characterized spontaneous animal model of type 2 diabetes. The CREM repressor levels are increased, and the expression of insulin mRNA is decreased in GK rats, suggesting that increased CREM repressor expression in pancreatic islets could contribute to the decreased insulin gene transcription that results in impaired insulin secretion in type 2 diabetes.
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Affiliation(s)
- A Inada
- Department of Metabolism and Clinical Nutrition, Faculty of Medicine, Kyoto University, Japan
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9
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Herdegen T, Leah JD. Inducible and constitutive transcription factors in the mammalian nervous system: control of gene expression by Jun, Fos and Krox, and CREB/ATF proteins. BRAIN RESEARCH. BRAIN RESEARCH REVIEWS 1998; 28:370-490. [PMID: 9858769 DOI: 10.1016/s0165-0173(98)00018-6] [Citation(s) in RCA: 1049] [Impact Index Per Article: 40.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
This article reviews findings up to the end of 1997 about the inducible transcription factors (ITFs) c-Jun, JunB, JunD, c-Fos, FosB, Fra-1, Fra-2, Krox-20 (Egr-2) and Krox-24 (NGFI-A, Egr-1, Zif268); and the constitutive transcription factors (CTFs) CREB, CREM, ATF-2 and SRF as they pertain to gene expression in the mammalian nervous system. In the first part we consider basic facts about the expression and activity of these transcription factors: the organization of the encoding genes and their promoters, the second messenger cascades converging on their regulatory promoter sites, the control of their transcription, the binding to dimeric partners and to specific DNA sequences, their trans-activation potential, and their posttranslational modifications. In the second part we describe the expression and possible roles of these transcription factors in neural tissue: in the quiescent brain, during pre- and postnatal development, following sensory stimulation, nerve transection (axotomy), neurodegeneration and apoptosis, hypoxia-ischemia, generalized and limbic seizures, long-term potentiation and learning, drug dependence and withdrawal, and following stimulation by neurotransmitters, hormones and neurotrophins. We also describe their expression and possible roles in glial cells. Finally, we discuss the relevance of their expression for nervous system functioning under normal and patho-physiological conditions.
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Affiliation(s)
- T Herdegen
- Institute of Pharmacology, University of Kiel, Hospitalstrasse 4, 24105, Kiel,
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Müller FU, Bokník P, Knapp J, Neumann J, Vahlensieck U, Oetjen E, Scheld HH, Schmitz W. Identification and expression of a novel isoform of cAMP response element modulator in the human heart. FASEB J 1998; 12:1191-9. [PMID: 9737722 DOI: 10.1096/fasebj.12.12.1191] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In end-stage human heart failure, excessive beta-adrenergic stimulation of the cAMP-dependent signaling pathway due to enhanced endogenous catecholamines is hypothesized to contribute to expressional alterations of myocardial regulatory proteins. The cAMP response element modulator (CREM) regulates the transcription of cAMP-responsive genes and might be involved in the regulation of cardiac gene expression. Using the reverse transcription polymerase chain reaction, we identified a novel CREM mRNA, CREM-Ib deltaC-X, in the human heart. Overexpression of CREM-Ib deltaC-X decreased cAMP response element (CRE) -mediated gene transcription in HIT-T15 cells, and this activity was assigned to the part of the sequence encoding putative internally translated proteins. Two of three possible internally translated proteins were immunologically identified in cells overexpressing CREM-Ib deltaC-X tagged with the hemagglutinin epitope of the influenza virus. Both proteins were expressed in bacteria and showed CRE-specific DNA binding, formation of heterodimers with the cAMP response element binding protein (CREB), and inhibition of CREB's binding to the CRE. CREM expression was detected on the mRNA and protein levels in the human heart. We conclude that CREM-Ib deltaC-X generates internally translated repressors of CRE-mediated gene transcription, suggesting the first example for the existence and function of human cardiac CREM.
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Affiliation(s)
- F U Müller
- Institut für Pharmakologie und Toxikologie, Universität Münster, Germany.
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Abstract
Serum response factor (SRF) is a transcription factor which binds to the serum response element (SRE) in the c-fos promoter. It is required for regulated expression of the c-fos gene as well as other immediate-early genes and some tissue-specific genes. To better understand the regulation of SRF, we used a yeast interaction assay to screen a human HeLa cell cDNA library for SRF-interacting proteins. ATF6, a basic-leucine zipper protein, was isolated by binding to SRF and in particular to its transcriptional activation domain. The binding of ATF6 to SRF was also detected in vitro. An ATF6-VP16 chimera activated expression of an SRE reporter gene in HeLa cells, suggesting that ATF6 can interact with endogenous SRF. More strikingly, an antisense ATF6 construct reduced serum induction of a c-fos reporter gene, suggesting that ATF6 is involved in activation of transcription by SRF. ATF6 was previously partially cloned as a member of the ATF family. The complete cDNA of ATF6 was isolated, and its expression pattern was described.
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Affiliation(s)
- C Zhu
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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12
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Bodor J, Spetz AL, Strominger JL, Habener JF. cAMP inducibility of transcriptional repressor ICER in developing and mature human T lymphocytes. Proc Natl Acad Sci U S A 1996; 93:3536-41. [PMID: 8622971 PMCID: PMC39645 DOI: 10.1073/pnas.93.8.3536] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Stimulation of the cAMP-dependent signaling pathway exerts an inhibitory effect on the proliferation and effector functions of T cells. The ability of T cells to form high intracellular levels of cAMP is acquired during development in the human thymus and is retained by the majority of mature peripheral T lymphocytes. Here we show that elevated cAMP levels in T cells correlate with the expression of the potent transcriptional repressor ICER (inducible cAMP early repressor) previously described in the hypothalamic-pituitary-gonadal axis. Further, in transcriptional assays in vivo, ICER inhibits calcineurin-mediated expression of the interleukin 2 promoter as well as Tax-mediated transactivation of the human T-lymphotropic virus type I (HTLV-I) promoter. Thus, the induction of ICER in T cells may play an important role in the cAMP-induced quiescence and the persistent latency of HTLV-I.
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Affiliation(s)
- J Bodor
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Boston, MA 02114, USA
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Bodor J, Walker W, Flemington E, Spetz AL, Habener JF. Modulation of Tax and PKA-mediated expression of HTLV-I promoter via cAMP response element binding and modulator proteins CREB and CREM. FEBS Lett 1995; 377:413-8. [PMID: 8549766 DOI: 10.1016/0014-5793(95)01299-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Nuclear proteins of the human peripheral blood T lymphocytes that bind to the CREs located within three 21-bp repeat enhancers of the HTLV-I promoter belong to the CREB/CREM family of bZIP transcription factors. It has been shown previously that Tax enhances transactivation of these CREs by direct interactions with the bZIP domain of the transcription factors to stabilize DNA-binding. We show that CREB and CREM bind all three CRE sequences of the HTLV-I promoter which are important determinants in Tax-elicited transactivation as well as PKA-mediated activation of the HTLV-I promoter. Tax and PKA activate transcription from a HTLV-I-LTR CAT reporter plasmid transfected to NIH 3T3 cells, and CREM attenuates the activation. In the context of a GAL4 CREB fusion protein in which the DNA-binding bZIP domain of CREB is replaced by GAL4 binding domain, a single amino acid substitution of serine-133, phosphorylated by PKA and critical for the transactivation function of CREB, attenuates both Tax and PKA-mediated transcriptional responses. These observations suggest that Tax enhances CREB-mediated transactivation of the HTLV-I promoter by a mechanism apart from, and/or in addition to, the reported stabilization of DNA-binding by interaction with the bZIP domain of CREB.
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Affiliation(s)
- J Bodor
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital (WEL320), Howard Hughes Medical Institute, Boston 02114, USA
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14
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Hamm MK, Schepartz A. Studies on the formation of DNA·protein interfaces: DNA specificity and straightening by CREB. Bioorg Med Chem Lett 1995. [DOI: 10.1016/0960-894x(95)00266-v] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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15
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Abstract
The development of cross-resistance to many natural product anticancer drugs, termed multidrug resistance (MDR), is a serious limitation to cancer chemotherapy. MDR is often associated with overexpression of the MDR1 gene product, P-glycoprotein, a multifunctional drug transporter. Understanding the mechanisms that regulate the transcriptional activation of MDR1 may afford a means of reducing or eliminating MDR. We have found that MDR1 expression can be modulated by type I cAMP-dependent protein kinase (PKA). This suggests that MDR may be modulated by selectively downregulating PKA activity to effect inhibition of PKA-dependent trans-activating factors which may be involved in MDR1 transcription. High levels of type I PKA occur in primary breast carcinomas and patients exhibiting this phenotype show decreased survival. The selective type I PKA inhibitors, 8-Cl-cAMP and Rp8-Cl-cAMP[S], may be particularly useful for downregulating PKA, and inhibit transient expression of a reporter gene under the control of MDR1 promoter elements. Thus, investigations of the signalling pathways involved in transcriptional regulation of MDR1 may lead to a greater understanding of the mechanisms governing the expression of MDR and provide a focus for pharmacological intervention.
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Affiliation(s)
- C Rohlff
- Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20007, USA
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16
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Pennypacker KR, Hudson PM, Hong JS, McMillian MK. DNA binding activity of CREB transcription factors during ontogeny of the central nervous system. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 1995; 86:242-9. [PMID: 7656416 DOI: 10.1016/0165-3806(95)00033-a] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
During the early postnatal period, the rat brain contains high basal levels of AP-1 DNA binding activity which declines to the low levels found in the adult by the third postnatal week. Although the individual transcription factors that comprise this AP-1 DNA binding complex had not been identified, we discovered that these proteins were immunoreactive to the cAMP responsive element binding protein (CREB) and also recognized the CRE element. The 45 kDa CREB-immunoreactive protein was detected at high levels only during the first postnatal week. CRE and AP-1 DNA binding activities were studied in the olfactory bulb, striatum, hindbrain, hippocampus, hypothalamus and cerebellum. In general, the DNA binding activity correlated with the stage of maturation of the particular brain region. However, basal AP-1 DNA binding in the olfactory bulb from adults remained slightly elevated relative to other brain regions. Interestingly, the DNA binding complex in the olfactory bulb began to include fos-related antigen as well as CREB by the third postnatal week. The fra-containing complex only recognizes the AP-1 element, while the CREB complex can bind to either CRE or AP-1 sequences. Thus, there is crosstalk between the signal transduction systems that activate CREB and AP-1 transcription factors. This elevated CREB DNA binding activity may be a sensitive index for studying the development of the brain and could be involved in modulating the genomic program in differentiating cells.
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Affiliation(s)
- K R Pennypacker
- Laboratory of Environmental Neuroscience, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA
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Habener JF, Miller CP, Vallejo M. cAMP-dependent regulation of gene transcription by cAMP response element-binding protein and cAMP response element modulator. VITAMINS AND HORMONES 1995; 51:1-57. [PMID: 7483321 DOI: 10.1016/s0083-6729(08)61037-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- J F Habener
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02114, USA
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Affiliation(s)
- M Vallejo
- Department of Medicine, Massachusetts General Hospital, Harvard Medical School, Boston 02114
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A monomeric derivative of the cellular transcription factor CREB functions as a constitutive activator. Mol Cell Biol 1994. [PMID: 7935435 DOI: 10.1128/mcb.14.11.7204] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mammalian transcriptional activator CREB binds as a dimer to a broad spectrum of inducible promoters. CREB activity is modulated by several signalling agents (protein kinase A [PKA], Ca2+, and transforming growth factor beta) and via functional interactions with cell-specific transcription factors. In addition, CREB can activate transcription constitutively and repress the activity of several other transcriptional activators. The mechanisms that allow CREB to act in such a malleable manner and the role that CREB dimerization might play in this are poorly understood. To probe the latter issue, we have created monomeric forms of CREB by fusing CREB to the DNA-binding domain of a protein (B-cell specific activator protein [BSAP]) that binds to DNA as a monomer. Remarkably, monomeric CREB acts as a potent, constitutive activator under conditions in which native CREB is inducible by PKA. Thus, CREB contains constitutive activation regions that are unable to function in native CREB. Two glutamine-rich domains that are important for native, PKA-inducible CREB activity are required for the constitutive activity of monomeric CREB. In contrast, two elements within the kinase-inducible domain of CREB are dispensable for constitutive activity. We discuss our results in relation to inducible and constitutive CREB activity and the potential modes of action of other activators that directly interact with CREB.
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Krajewski W, Lee KA. A monomeric derivative of the cellular transcription factor CREB functions as a constitutive activator. Mol Cell Biol 1994; 14:7204-10. [PMID: 7935435 PMCID: PMC359254 DOI: 10.1128/mcb.14.11.7204-7210.1994] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The mammalian transcriptional activator CREB binds as a dimer to a broad spectrum of inducible promoters. CREB activity is modulated by several signalling agents (protein kinase A [PKA], Ca2+, and transforming growth factor beta) and via functional interactions with cell-specific transcription factors. In addition, CREB can activate transcription constitutively and repress the activity of several other transcriptional activators. The mechanisms that allow CREB to act in such a malleable manner and the role that CREB dimerization might play in this are poorly understood. To probe the latter issue, we have created monomeric forms of CREB by fusing CREB to the DNA-binding domain of a protein (B-cell specific activator protein [BSAP]) that binds to DNA as a monomer. Remarkably, monomeric CREB acts as a potent, constitutive activator under conditions in which native CREB is inducible by PKA. Thus, CREB contains constitutive activation regions that are unable to function in native CREB. Two glutamine-rich domains that are important for native, PKA-inducible CREB activity are required for the constitutive activity of monomeric CREB. In contrast, two elements within the kinase-inducible domain of CREB are dispensable for constitutive activity. We discuss our results in relation to inducible and constitutive CREB activity and the potential modes of action of other activators that directly interact with CREB.
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Affiliation(s)
- W Krajewski
- Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom
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ATF-a0, a novel variant of the ATF/CREB transcription factor family, forms a dominant transcription inhibitor in ATF-a heterodimers. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42236-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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Lee KA, Masson N. Transcriptional regulation by CREB and its relatives. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1174:221-33. [PMID: 8373801 DOI: 10.1016/0167-4781(93)90191-f] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- K A Lee
- Imperial Cancer Research Fund, Clare Hall Laboratories, Potters Bar, UK
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Vallejo M, Ron D, Miller CP, Habener JF. C/ATF, a member of the activating transcription factor family of DNA-binding proteins, dimerizes with CAAT/enhancer-binding proteins and directs their binding to cAMP response elements. Proc Natl Acad Sci U S A 1993; 90:4679-83. [PMID: 8506317 PMCID: PMC46576 DOI: 10.1073/pnas.90.10.4679] [Citation(s) in RCA: 197] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Members of the C/EBP family of basic-leucine zipper (bZip) transcription factors form heterodimers and bind to the CAAT box and other sequence-related enhancer motifs. Using a 32P-labeled protein probe consisting of the bZip domain of C/EBP beta, we isolated a clone encoding C/EBP-related ATF (C/ATF), a bZip protein that heterodimerizes with C/EBP-like proteins but belongs to the CREB/ATF family. C/ATF homodimers do not bind to typical C/EBP DNA sites. Instead they bind to palindromic cAMP response elements such as that of the somatostatin gene. In addition, C/ATF-C/EBP beta heterodimers bind to a subclass of asymmetric cAMP response elements exemplified by those in the phosphoenolpyruvate carboxykinase and proenkephalin genes. Transient transfection studies indicate that interactions between C/ATF and C/EBP beta are the basis for a functional cross talk between these two families of transcription factors that may be important for the integration of hormonal and developmental stimuli that determine the expression of subsets of genes in specific cellular phenotypes.
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Affiliation(s)
- M Vallejo
- Laboratory of Molecular Endocrinology, Massachusetts General Hospital, Howard Hughes Medical Institute, Harvard Medical School, Boston 02114
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