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Wang P, Leung CH, Ma DL, Sun RWY, Yan SC, Chen QS, Che CM. Specific blocking of CREB/DNA binding by cyclometalated platinum(II) complexes. Angew Chem Int Ed Engl 2011; 50:2554-8. [PMID: 21370336 DOI: 10.1002/anie.201006887] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Indexed: 11/12/2022]
Affiliation(s)
- Ping Wang
- Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Pokfulam Road, Hong Kong, P.R. China
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152
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CRTC3 links catecholamine signalling to energy balance. Nature 2011; 468:933-9. [PMID: 21164481 DOI: 10.1038/nature09564] [Citation(s) in RCA: 119] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Accepted: 10/11/2010] [Indexed: 01/05/2023]
Abstract
The adipose-derived hormone leptin maintains energy balance in part through central nervous system-mediated increases in sympathetic outflow that enhance fat burning. Triggering of β-adrenergic receptors in adipocytes stimulates energy expenditure by cyclic AMP (cAMP)-dependent increases in lipolysis and fatty-acid oxidation. Although the mechanism is unclear, catecholamine signalling is thought to be disrupted in obesity, leading to the development of insulin resistance. Here we show that the cAMP response element binding (CREB) coactivator Crtc3 promotes obesity by attenuating β-adrenergic receptor signalling in adipose tissue. Crtc3 was activated in response to catecholamine signals, when it reduced adenyl cyclase activity by upregulating the expression of Rgs2, a GTPase-activating protein that also inhibits adenyl cyclase activity. As a common human CRTC3 variant with increased transcriptional activity is associated with adiposity in two distinct Mexican-American cohorts, these results suggest that adipocyte CRTC3 may play a role in the development of obesity in humans.
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153
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Ely HA, Mellon PL, Coss D. GnRH induces the c-Fos gene via phosphorylation of SRF by the calcium/calmodulin kinase II pathway. Mol Endocrinol 2011; 25:669-80. [PMID: 21292826 DOI: 10.1210/me.2010-0437] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Despite extensive studies on GnRH regulation of the gonadotropin subunit genes, very little is known about mechanism of induction of intermediary immediate early genes, such as c-Fos, that are direct targets of GnRH signaling and that upon induction, activate transcription of gonadotropin genes. Although c-Fos is induced by a variety of stimuli in other cell types, in the gonadotropes, only GnRH induces c-Fos and through it FSHβ. Thus, understanding the specificity of c-Fos induction by GnRH will provide insight into GnRH regulation of FSHβ gene expression. GnRH induction of c-Fos in LβT2 cells requires the serum response factor (SRF)-binding site, but not the Ets/ELK1 site. This is in contrast to c-Fos induction by growth factors in other cells, which activate c-Fos transcription via phosphorylation of ELK1 and require the ELK1-binding site. The SRF site alone is sufficient for induction by GnRH, whereas induction by 12-tetradecanoylphorbol-13-acetate (TPA) requires both the ELK1 and SRF sites. Although ELK1 site is not required, upon GnRH stimulation, ELK1 interacts with SRF and is recruited to the SRF site. GnRH phosphorylates ELK1 through ERK1/2 and p38 MAPK, which correlates with the signaling pathways necessary for c-Fos and FSHβ induction. GnRH also causes phosphorylation of SRF through calmodulin-dependent kinase II (CamKII), which leads to increased binding to its site. CamKII activation is sufficient for phosphorylation of SRF and for induction of the c-Fos gene through the SRF site. Thus, GnRH uses a combination of growth factor signaling and the CamKII pathway to induce c-Fos to regulate FSHβ gene expression in gonadotrope cells.
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Affiliation(s)
- Heather A Ely
- Department of Reproductive Medicine, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0674, USA
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154
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Seoane A, Tinsley CJ, Brown MW. Interfering with perirhinal brain-derived neurotrophic factor expression impairs recognition memory in rats. Hippocampus 2011; 21:121-6. [PMID: 20087891 PMCID: PMC4258639 DOI: 10.1002/hipo.20763] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The role of brain-derived neurotrophic factor (BDNF) in recognition memory was investigated by locally infusing oligodeoxynucleotides (ODNs) into perirhinal cortex, a region of the temporal lobe essential for familiarity discrimination. Antisense but not sense BDNF ODN impaired consolidation of long-term (24 h) but not shorter-term (20 min) recognition memory.
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Affiliation(s)
- Ana Seoane
- Department of Anatomy, Medical Research Council, Centre for Synaptic Plasticity, University of Bristol, Bristol, UK
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155
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Creb and Sp/Krüppel response elements cooperate to control rat TRH gene transcription in response to cAMP. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2011; 1809:191-9. [PMID: 21266205 DOI: 10.1016/j.bbagrm.2011.01.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 01/18/2011] [Accepted: 01/20/2011] [Indexed: 12/17/2022]
Abstract
Expression of hypophysiotropic TRH, that controls thyroid axis activity, is increased by cold exposure; this effect is mimicked in rat hypothalamic cells incubated with norepinephrine or cAMP analogs. TRH proximal promoter contains three putative CRE: Site-4 or CRE-1 that overlaps an element recognized by thyroid hormone receptors, CRE-2 with adjacent sequences GC box or CACCC recognized by Sp/Krüppel factors (extended CRE-2), and AP-1 sites flanking a GRE(1/2). To evaluate the role of each element in the cAMP response, these sites were mutated or deleted in rat TRH promoter linked to luciferase gene (TRH-luc) and co-transfected with β-gal expression vector in various cell lines; C6 cells gave the highest response to forskolin. Basal activity was most affected by mutations or deletion of CRE-2 site, or CACCC (50-75% of wild type-WT). Forskolin-induced 3× stimulation in WT which decreased 25% with CRE-1 or AP-1 deletions, but 50% when CRE-2 or its 5' adjacent GC box was altered. SH-SY5Y cells co-transfected with CREB-expression vector increased dB-cAMP response in the wild type but not in the CRE-2 mutated plasmid; cotransfecting CREB-A (a dominant negative expression vector) strongly diminished basal or cAMP response. Primary cultures of hypothalamic cells transfected with plasmids containing deletions of CRE-1, CRE-2, or extended CRE-2 failed to respond to forskolin when CRE-2 was modified. These results corroborate the CRE-2 site as the main cAMP-response element of rat TRH promoter, not exclusive of transcription factors of hypothalamic cells, and stress the relevance of adjacent Sp-1 sites, important mediators of some metabolic hormones.
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156
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CpG methylation of half-CRE sequences creates C/EBPalpha binding sites that activate some tissue-specific genes. Proc Natl Acad Sci U S A 2010; 107:20311-6. [PMID: 21059933 DOI: 10.1073/pnas.1008688107] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
DNA methylation of the cytosine in the CpG dinucleotide is typically associated with gene silencing. Genomic analyses have identified low CpG promoters that are both methylated and transcriptionally active, but the mechanism underlying the activation of these methylated promoters remains unclear. Here we show that CpG methylation of the CRE sequence (TGACGTCA) enhances the DNA binding of the C/EBPα transcription factor, a protein critical for activation of differentiation in various cell types. Transfection assays also show that C/EBPα activates the CRE sequence only when it is methylated. The biological significance of this observation was seen in differentiating primary keratinocyte cultures from newborn mice where certain methylated promoters are both bound by C/EBPα and activated upon differentiation. Experimental demethylation by either 5-azacytidine treatment or DNMT1 depletion diminished both C/EBPα binding and activation of the same methylated promoters upon differentiation suggesting that CpG methylation can localize C/EBPα. Transfection studies in cell cultures using methylated tissue-specific proximal promoters identified half-CRE (CGTCA) and half-C/EBP (CGCAA) sequences that need to be methylated for C/EBPα mediated activation. In primary dermal fibroblasts, C/EBPα activates a different set of methylated tissue-specific promoters upon differentiation into adipocytes. These data identify a new function for methyl CpGs: producing DNA binding sites at half-CRE and half-C/EBP sequences for C/EBPα that are needed to activate tissue-specific genes.
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157
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Musunuru K, Strong A, Frank-Kamenetsky M, Lee NE, Ahfeldt T, Sachs KV, Li X, Li H, Kuperwasser N, Ruda VM, Pirruccello JP, Muchmore B, Prokunina-Olsson L, Hall JL, Schadt EE, Morales CR, Lund-Katz S, Phillips MC, Wong J, Cantley W, Racie T, Ejebe KG, Orho-Melander M, Melander O, Koteliansky V, Fitzgerald K, Krauss RM, Cowan CA, Kathiresan S, Rader DJ. From noncoding variant to phenotype via SORT1 at the 1p13 cholesterol locus. Nature 2010; 466:714-9. [PMID: 20686566 DOI: 10.1038/nature09266] [Citation(s) in RCA: 866] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2009] [Accepted: 06/09/2010] [Indexed: 12/27/2022]
Abstract
Recent genome-wide association studies (GWASs) have identified a locus on chromosome 1p13 strongly associated with both plasma low-density lipoprotein cholesterol (LDL-C) and myocardial infarction (MI) in humans. Here we show through a series of studies in human cohorts and human-derived hepatocytes that a common noncoding polymorphism at the 1p13 locus, rs12740374, creates a C/EBP (CCAAT/enhancer binding protein) transcription factor binding site and alters the hepatic expression of the SORT1 gene. With small interfering RNA (siRNA) knockdown and viral overexpression in mouse liver, we demonstrate that Sort1 alters plasma LDL-C and very low-density lipoprotein (VLDL) particle levels by modulating hepatic VLDL secretion. Thus, we provide functional evidence for a novel regulatory pathway for lipoprotein metabolism and suggest that modulation of this pathway may alter risk for MI in humans. We also demonstrate that common noncoding DNA variants identified by GWASs can directly contribute to clinical phenotypes.
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Affiliation(s)
- Kiran Musunuru
- Cardiovascular Research Center and Center for Human Genetic Research, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02114, USA
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158
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CBP/p300 double null cells reveal effect of coactivator level and diversity on CREB transactivation. EMBO J 2010; 29:3660-72. [PMID: 20859256 DOI: 10.1038/emboj.2010.235] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Accepted: 08/30/2010] [Indexed: 11/08/2022] Open
Abstract
It remains uncertain how the DNA sequence of mammalian genes influences the transcriptional response to extracellular signals. Here, we show that the number of CREB-binding sites (CREs) affects whether the related histone acetyltransferases (HATs) CREB-binding protein (CBP) and p300 are required for endogenous gene transcription. Fibroblasts with both CBP and p300 knocked-out had strongly attenuated histone H4 acetylation at CREB-target genes in response to cyclic-AMP, yet transcription was not uniformly inhibited. Interestingly, dependence on CBP/p300 was often different between reporter plasmids and endogenous genes. Transcription in the absence of CBP/p300 correlated with endogenous genes having more CREs, more bound CREB, and more CRTC2 (a non-HAT coactivator of CREB). Indeed, CRTC2 rescued cAMP-inducible expression for certain genes in CBP/p300 null cells and contributed to the CBP/p300-independent expression of other targets. Thus, endogenous genes with a greater local concentration and diversity of coactivators tend to have more resilient-inducible expression. This model suggests how gene expression patterns could be tuned by altering coactivator availability rather than by changing signal input or transcription factor levels.
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159
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Ma Z, Kwong KYC, Tovar JP, Paek D. Cyclic adenosine monophosphate induces plasminogen activator inhibitor-1 expression in human mast cells. Biochem Biophys Res Commun 2010; 400:569-74. [PMID: 20816667 DOI: 10.1016/j.bbrc.2010.08.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2010] [Accepted: 08/25/2010] [Indexed: 02/02/2023]
Abstract
Plaminogen activator inhibitor-1 (PAI-1), the key physiological inhibitor of the plasmin fibrinolytic system, plays important roles in the pathogenesis of asthma. Mast cells (MCs) are crucial effector cells and a major source of PAI-1 for asthma. Cyclic adenosine monophosphate (cAMP) is the important regulator of MCs; however, its effects on PAI-1 expression in MCs remain unknown. We reported cAMP/protein kinase A pathway positively regulates PAI-1 expression through cAMP-response element binding protein binding to hypoxia response element-1 at -158 to -153bp of human PAI-1 promoter in human MCs. Moreover, cAMP synergistically augments PAI-1 expression with ionomycin- or IgE receptor cross-linking-mediated stimulation.
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Affiliation(s)
- Zhongcai Ma
- Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, David Geffen School of Medicine, University of California, Los Angeles (UCLA), Torrance, CA 90502, USA.
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160
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Herold S, Jagasia R, Merz K, Wassmer K, Lie DC. CREB signalling regulates early survival, neuronal gene expression and morphological development in adult subventricular zone neurogenesis. Mol Cell Neurosci 2010; 46:79-88. [PMID: 20801218 DOI: 10.1016/j.mcn.2010.08.008] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2010] [Revised: 07/30/2010] [Accepted: 08/15/2010] [Indexed: 01/22/2023] Open
Abstract
Neural stem cells in the subventricular zone (SVZ) of the lateral ventricles give rise to new interneurons of the olfactory bulb (OB) throughout life. SVZ/OB neurogenesis is influenced by olfactory network activity, which modulates the survival of new neurons during their integration into the OB network. Previous work suggested that such activity-dependent survival is regulated via the CREB signalling pathway. Curiously, CREB signalling is already active during the early developmental stages of adult SVZ/OB neurogenesis. To investigate the role of cell autonomous CREB signalling during early stages of adult SVZ/OB neurogenesis, we ablated CREB-pathway activity in the SVZ/OB neurogenic lineage using a retroviral strategy. Surprisingly, loss of CREB signalling resulted in increased cell death and loss of expression of the neurogenic transcription factor Pax 6, and of a subset of neuronal proteins in migrating neurons of the RMS. Moreover, post-migratory neurons in the OB displayed impaired dendritic development. These results demonstrate an essential role for CREB signalling in maturation of newborn neurons in the OB and uncover a novel role for CREB signalling in the survival and maintenance of neuronal gene expression during the early stages of SVZ/OB neurogenesis.
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Affiliation(s)
- S Herold
- Research Group Adult Neurogenesis and Neural Stem Cells, Institute of Developmental Genetics, Helmholtz Zentrum München, German Research Center for Environmental Health, 85764 Munich-Neuherberg, Germany
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161
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Finsterwald C, Fiumelli H, Cardinaux JR, Martin JL. Regulation of dendritic development by BDNF requires activation of CRTC1 by glutamate. J Biol Chem 2010; 285:28587-95. [PMID: 20639200 DOI: 10.1074/jbc.m110.125740] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dendritic growth is essential for the establishment of a functional nervous system. Among extrinsic signals that control dendritic development, substantial evidence indicates that BDNF regulates dendritic morphology. However, little is known about the underlying mechanisms by which BDNF controls dendritic growth. In this study, we show that the MAPK signaling pathway and the transcription factor cAMP response element-binding protein (CREB) mediate the effects of BDNF on dendritic length and complexity. However, phosphorylation of CREB alone is not sufficient for the stimulation of dendritic growth by BDNF. Thus, using a mutant form of CREB unable to bind CREB-regulated transcription coactivator (CRTC1), we demonstrate that this effect also requires a functional interaction between CREB and CRTC1. Moreover, inhibition of CRTC1 expression by shRNA-mediated knockdown abolished BDNF-induced dendritic growth of cortical neurons. Interestingly, we found that nuclear translocation of CRTC1 results from activation of NMDA receptors by glutamate, a process that is essential for the effects of BDNF on dendritic development. Together, these data identify a previously unrecognized mechanism by which CREB and the coactivator CRTC1 mediate the effects of BDNF on dendritic growth.
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Affiliation(s)
- Charles Finsterwald
- Department of Physiology, University of Lausanne, CH-1005 Lausanne, Switzerland
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162
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Son DS, Terranova PF, Roby KF. Interaction of adenosine 3',5'-cyclic monophosphate and tumor necrosis factor-alpha on serum amyloid A3 expression in mouse granulosa cells: dependence on CCAAT-enhancing binding protein-beta isoform. Endocrinology 2010; 151:3407-19. [PMID: 20444945 PMCID: PMC2903928 DOI: 10.1210/en.2009-1321] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
TNFalpha is an inflammatory-related cytokine that has inhibitory effects on gonadotropin- and cAMP-stimulated steroidogenesis and folliculogenesis. Because ovulation is an inflammatory reaction and TNF specifically induces serum amyloid A3 (SAA3) in mouse granulosa cells, the effect of cAMP on TNF-induced SAA3 promoter activity, mRNA and protein was investigated. Granulosa cells from immature mice were cultured with TNF and/or cAMP. TNF increased SAA3 promoter activity, mRNA, and protein, which were further increased by cAMP. cAMP alone increased SAA3 promoter activity, but SAA3 mRNA and protein remained undetectable. Thus, there appeared to be different mechanisms by which TNF and cAMP regulated SAA3 expression. SAA3 promoters lacking a nuclear factor (NF)-kappaB-like site or containing its mutant were not responsive to TNF but were responsive to cAMP. Among four CCAAT-enhancing binding protein (C/EBP) sites in the SAA3 promoter, the C/EBP site nearest the NF-kappaB-like site was required for TNF-induced SAA3. The C/EBP site at -75/-67 was necessary for responsiveness to cAMP. Dominant-negative C/EBP and cAMP response element-binding protein or short interfering RNA of C/EBPbeta blocked TNF- or cAMP-induced SAA3 promoter activity. The combination of TNF and cAMP increased C/EBPbeta protein above that induced by TNF or cAMP alone. Thus, cAMP in combination with TNF specifically induced C/EBPbeta protein, leading to enhanced SAA3 expression but requiring NF-kappaB in mouse granulose cells. In addition, like TNF, SAA inhibited cAMP-induced estradiol accumulation and CYP19 levels. These data indicate SAA may play a role in events occurring during the ovulation process.
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Affiliation(s)
- Deok-Soo Son
- Department of Obstetrics and Gynecology, Meharry Medical College, Nashville, TN 37208, USA
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163
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Staples CJ, Owens DM, Maier JV, Cato ACB, Keyse SM. Cross-talk between the p38alpha and JNK MAPK pathways mediated by MAP kinase phosphatase-1 determines cellular sensitivity to UV radiation. J Biol Chem 2010; 285:25928-40. [PMID: 20547488 PMCID: PMC2923983 DOI: 10.1074/jbc.m110.117911] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
MAPK phosphatase-1 (DUSP1/MKP-1) is a mitogen and stress-inducible dual specificity protein phosphatase, which can inactivate all three major classes of MAPK in mammalian cells. DUSP1/MKP-1 is implicated in cellular protection against a variety of genotoxic insults including hydrogen peroxide, ionizing radiation, and cisplatin, but its role in the interplay between different MAPK pathways in determining cell death and survival is not fully understood. We have used pharmacological and genetic tools to demonstrate that DUSP1/MKP-1 is an essential non-redundant regulator of UV-induced cell death in mouse embryo fibroblasts (MEFs). The induction of DUSP1/MKP-1 mRNA and protein in response to UV radiation is mediated by activation of the p38α but not the JNK1 or JNK2 MAPK pathways. Furthermore, we identify MSK1 and -2 and their downstream effectors cAMP-response element-binding protein/ATF1 as mediators of UV-induced p38α-dependent DUSP1/MKP-1 transcription. Dusp1/Mkp-1 null MEFs display increased signaling through both the p38α and JNK MAPK pathways and are acutely sensitive to UV-induced apoptosis. This lethality is rescued by the reintroduction of wild-type DUSP1/MKP-1 and by a mutant of DUSP1/MKP-1, which is unable to bind to either p38α or ERK1/2, but retains full activity toward JNK. Importantly, whereas small interfering RNA-mediated knockdown of DUSP1/MKP-1 sensitizes wild-type MEFs to UV radiation, DUSP1/MKP-1 knockdown in MEFS lacking JNK1 and -2 does not result in increased cell death. Our results demonstrate that cross-talk between the p38α and JNK pathways mediated by induction of DUSP1/MKP-1 regulates the cellular response to UV radiation.
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Affiliation(s)
- Christopher J Staples
- CR-UK Stress Response Laboratory, Biomedical Research Institute, Ninewells Hospital and Medical School, University of Dundee, Dundee, Scotland, UK
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164
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Common functional genetic variants in catecholamine storage vesicle protein promoter motifs interact to trigger systemic hypertension. J Am Coll Cardiol 2010; 55:1463-75. [PMID: 20359597 DOI: 10.1016/j.jacc.2009.11.064] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Revised: 11/10/2009] [Accepted: 11/24/2009] [Indexed: 12/28/2022]
Abstract
OBJECTIVES The purpose of this study is to understand whether naturally occurring genetic variation in the promoter of chromogranin B (CHGB), a major constituent of catecholamine storage vesicles, is functional and confers risk for cardiovascular disease. BACKGROUND CHGB plays a necessary (catalytic) role in catecholamine storage vesicle biogenesis. Previously, we found that genetic variation at CHGB influenced autonomic function, with association maximal toward the 5' region. METHODS Here we explored transcriptional mechanisms of such effects, characterizing 2 common variants in the proximal promoter, A-296C and A-261T, using transfection/cotransfection, electrophoretic mobility shift assay (EMSA), and chromatin immunoprecipitation (ChIP). We then tested the effects of promoter variation on cardiovascular traits. RESULTS The A-296C disrupted a c-FOS motif, exhibiting differential mobility shifting to chromaffin cell nuclear proteins during EMSA, binding of endogenous c-FOS on ChIP, and differential response to exogenous c-FOS. The A-261T disrupted motifs for SRY and YY1, with similar consequences for EMSA, endogenous factor binding, and responses to exogenous factors. The 2-SNP CHGB promoter haplotypes had a profound (p=3.16E-20) effect on blood pressure (BP) in the European ancestry population, with a rank order of CT<AA<<CA<AT on both systolic blood pressure (SBP) and diastolic blood pressure (DBP), accounting for approximately 2.3% to approximately 3.4% of SBP/DBP variance; the haplotype effects on BP in vivo paralleled those on promoter activity in cella. Site-by-site interactions at A-296C and A-261T yielded highly nonadditive effects on SBP/DBP. The CHGB haplotype effects on BP were also noted in an independent (African ancestry) sample. In normotensive twins, parallel effects were noted for a pre-hypertensive phenotype, BP response to environmental stress. CONCLUSIONS The common CHGB promoter variants A-296C and A-261T, and their consequent haplotypes, alter binding of specific transcription factors to influence gene expression in cella as well as BP in vivo. Such variation contributes substantially to risk for human hypertension. Involvement of the sex-specific factor SRY suggests a novel mechanism for development of sexual dimorphism in BP.
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165
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Brown HJ, Peng L, Harada JN, Walker JR, Cole S, Lin SF, Zack JA, Chanda SK, Sun R. Gene expression and transcription factor profiling reveal inhibition of transcription factor cAMP-response element-binding protein by gamma-herpesvirus replication and transcription activator. J Biol Chem 2010; 285:25139-53. [PMID: 20516076 DOI: 10.1074/jbc.m110.137737] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Herpesvirus replication involves the expression of over 80 viral genes in a well ordered sequence, leading to the production of new virions. Viral genes expressed during the earliest phases of replication often regulate both viral and cellular genes. Therefore, they have the potential to bring about dramatic functional changes within the cell. Replication and transcription activator (RTA) is a potent immediate early transcription activator of the gamma-herpesvirus family. This family includes Epstein-Barr virus and Kaposi sarcoma-associated herpesvirus, human pathogens associated with malignancy. Here we combine gene array technology with transcription factor profiling to identify the earliest DNA promoter and cellular transcription factor targets of RTA in the cellular genome. We find that expression of RTA leads to both activation and inhibition of distinct groups of cellular genes. The identity of the target genes suggests that RTA rapidly changes the cellular environment to counteract cell death pathways, support growth factor signaling, and also promote immune evasion of the infected cell. Transcription factor profiling of the target gene promoters highlighted distinct pathways involved in gene activation at specific time points. Most notable throughout was the high level of cAMP-response element-binding protein (CREB)-response elements in RTA target genes. We find that RTA can function as either an activator or an inhibitor of CREB-response genes, depending on the promoter context. The association with CREB also highlights a novel connection and coordination between viral and cellular "immediate early" responses.
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Affiliation(s)
- Helen J Brown
- Department of Microbiology, Division of Hematology-Oncology, David Geffen School of Medicine, UCLA, Los Angeles, California 90095, USA.
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166
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de Lartigue G, Dimaline R, Varro A, Raybould H, de la Serre CB, Dockray GJ. Cocaine- and amphetamine-regulated transcript mediates the actions of cholecystokinin on rat vagal afferent neurons. Gastroenterology 2010; 138:1479-90. [PMID: 19854189 PMCID: PMC2847060 DOI: 10.1053/j.gastro.2009.10.034] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2009] [Revised: 10/01/2009] [Accepted: 10/13/2009] [Indexed: 12/29/2022]
Abstract
BACKGROUND & AIMS Cholecystokinin (CCK) acts on vagal afferent neurons to inhibit food intake and gastric emptying; it also increases expression of the neuropeptide cocaine- and amphetamine-regulated transcript (CART), but the significance of this is unknown. We investigated the role of CARTp in vagal afferent neurons. METHODS Release of CART peptide (CARTp) from cultured vagal afferent neurons was determined by enzyme-linked immunosorbent assay. Expression of receptors and neuropeptides in rat vagal afferent neurons in response to CARTp was studied using immunohistochemistry and luciferase promoter reporter constructs. Effects of CARTp and CCK were studied on food intake. RESULTS CCK stimulated CARTp release from cultured nodose neurons. CARTp replicated the effect of CCK in stimulating expression of Y2R and of CART itself in these neurons in vivo and in vitro, but not in inhibiting cannabinoid-1, melanin-concentrating hormone, and melanin-concentrating hormone-1 receptor expression. Effects of CCK on Y2R and CART expression were reduced by CART small interfering RNA or brefeldin A. Exposure of rats to CARTp increased the inhibitory action of CCK on food intake after short-, but not long-duration, fasting. CONCLUSIONS The actions of CCK in stimulating CART and Y2R expression in vagal afferent neurons and in inhibiting food intake are augmented by CARTp; CARTp is released by CCK from these neurons, indicating that it acts as an autocrine excitatory mediator.
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Affiliation(s)
- Guillaume de Lartigue
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
| | - Rod Dimaline
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
| | - Andrea Varro
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
| | - Helen Raybould
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, California, USA
| | - Claire Barbier de la Serre
- Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, UC Davis, California, USA
| | - Graham J. Dockray
- Physiological Laboratory, School of Biomedical Sciences, University of Liverpool, Crown St, Liverpool, L69 3BX, UK
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Vingtdeux V, Giliberto L, Zhao H, Chandakkar P, Wu Q, Simon JE, Janle EM, Lobo J, Ferruzzi MG, Davies P, Marambaud P. AMP-activated protein kinase signaling activation by resveratrol modulates amyloid-beta peptide metabolism. J Biol Chem 2010; 285:9100-13. [PMID: 20080969 PMCID: PMC2838330 DOI: 10.1074/jbc.m109.060061] [Citation(s) in RCA: 499] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Revised: 12/02/2009] [Indexed: 02/03/2023] Open
Abstract
Alzheimer disease is an age-related neurodegenerative disorder characterized by amyloid-beta (Abeta) peptide deposition into cerebral amyloid plaques. The natural polyphenol resveratrol promotes anti-aging pathways via the activation of several metabolic sensors, including the AMP-activated protein kinase (AMPK). Resveratrol also lowers Abeta levels in cell lines; however, the underlying mechanism responsible for this effect is largely unknown. Moreover, the bioavailability of resveratrol in the brain remains uncertain. Here we show that AMPK signaling controls Abeta metabolism and mediates the anti-amyloidogenic effect of resveratrol in non-neuronal and neuronal cells, including in mouse primary neurons. Resveratrol increased cytosolic calcium levels and promoted AMPK activation by the calcium/calmodulin-dependent protein kinase kinase-beta. Direct pharmacological and genetic activation of AMPK lowered extracellular Abeta accumulation, whereas AMPK inhibition reduced the effect of resveratrol on Abeta levels. Furthermore, resveratrol inhibited the AMPK target mTOR (mammalian target of rapamycin) to trigger autophagy and lysosomal degradation of Abeta. Finally, orally administered resveratrol in mice was detected in the brain where it activated AMPK and reduced cerebral Abeta levels and deposition in the cortex. These data suggest that resveratrol and pharmacological activation of AMPK have therapeutic potential against Alzheimer disease.
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Affiliation(s)
- Valérie Vingtdeux
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
| | - Luca Giliberto
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
| | - Haitian Zhao
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
| | - Pallavi Chandakkar
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
| | - Qingli Wu
- the New Use Agriculture and Natural Plant Products Program, Department of Plant Biology and Pathology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901
| | - James E. Simon
- the New Use Agriculture and Natural Plant Products Program, Department of Plant Biology and Pathology, Rutgers, The State University of New Jersey, New Brunswick, New Jersey 08901
| | | | - Jessica Lobo
- Food Science, Purdue University, West Lafayette, Indiana 47907, and
| | - Mario G. Ferruzzi
- the Departments of Foods and Nutrition and
- Food Science, Purdue University, West Lafayette, Indiana 47907, and
| | - Peter Davies
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
- the Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461
| | - Philippe Marambaud
- From the Litwin-Zucker Research Center for the Study of Alzheimer's Disease, The Feinstein Institute for Medical Research, North Shore-LIJ, Manhasset, New York 11030
- the Department of Pathology, Albert Einstein College of Medicine, Bronx, New York 10461
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168
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Rishi V, Oh WJ, Heyerdahl SL, Zhao J, Scudiero D, Shoemaker RH, Vinson C. 12 Arylstibonic acids that inhibit the DNA binding of five B-ZIP dimers. J Struct Biol 2010; 170:216-25. [PMID: 20176111 DOI: 10.1016/j.jsb.2010.02.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 02/16/2010] [Accepted: 02/16/2010] [Indexed: 01/07/2023]
Abstract
Previously, we identified an arylstibonic acid, NSC13778 that specifically binds to the basic region of the C/EBPalpha B-ZIP domain and disrupts DNA binding. We now examine a panel of 14 additional arylstibonic acid derivatives of NSC13778 for their ability to inhibit the DNA binding of five B-ZIP dimers (c-Fos|JunD, VBP, C/EBPalpha, C/EBPbeta, and CREB). They show various specificities at inhibiting the DNA binding of five B-ZIP domains. NSC13746 inhibits the DNA binding of C/EBPbeta and CREB at 100nM and promiscuously inhibiting the DNA binding of all five proteins in the 1muM range. Dialysis experiments indicate that NSC 13746 binding to the B-ZIP domain is reversible. Thermal denaturation studies indicate that NSC13746 binds the B-ZIP domain. Some compounds specifically inhibit DNA binding, with VBP and c-Fos|JunD being most easily disrupted. These compounds inhibit, with similar specificities to the pure B-ZIP domains, the DNA binding of nuclear extract to the AP1 DNA sequence but no inhibition is observed to SP1 containing oligonucleotide. Transient transfection assays indicate that NSC13746 can inhibit the TPA induced activation of two B-ZIP dependent reporters. These experiments suggest that arylstibonic acids are promising leads for inhibiting the DNA binding of a group of B-ZIP proteins in cells.
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Affiliation(s)
- Vikas Rishi
- Laboratory of Metabolism, National Cancer Institute, National Institutes of Health, Building 37, Room 3128, Bethesda, MD 20892, USA
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169
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NFIL3 and cAMP response element-binding protein form a transcriptional feedforward loop that controls neuronal regeneration-associated gene expression. J Neurosci 2010; 29:15542-50. [PMID: 20007478 DOI: 10.1523/jneurosci.3938-09.2009] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Successful regeneration of damaged neurons depends on the coordinated expression of neuron-intrinsic genes. At present however, there is no comprehensive view of the transcriptional regulatory mechanisms underlying neuronal regeneration. We used high-content cellular screening to investigate the functional contribution of 62 transcription factors to regenerative neuron outgrowth. Ten transcription factors are identified that either increase or decrease neurite outgrowth. One of these, NFIL3, is specifically upregulated during successful regeneration in vivo. Paradoxically however, knockdown of NFIL3 and overexpression of dominant-negative NFIL3 both increase neurite outgrowth. Our data show that NFIL3, together with CREB, forms an incoherent feedforward transcriptional regulatory loop in which NFIL3 acts as a negative regulator of CREB-induced regeneration-associated genes.
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170
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Wang J, Tang R, Lv M, Zhang J, Shen B. Selective unresponsiveness to the inhibition of p38 MAPK activation by cAMP helps L929 fibroblastoma cells escape TNF-alpha-induced cell death. Mol Cancer 2010; 9:6. [PMID: 20070884 PMCID: PMC2818697 DOI: 10.1186/1476-4598-9-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2009] [Accepted: 01/13/2010] [Indexed: 11/23/2022] Open
Abstract
Background The cyclic AMP (cAMP) signaling pathway has been reported to either promote or suppress cell death, in a cell context-dependent manner. Our previous study has shown that the induction of dynein light chain (DLC) by cAMP response element-binding protein (CREB) is required for cAMP-mediated inhibition of mitogen-activated protein kinase (MAPK) p38 activation in fibroblasts, which leads to suppression of NF-κB activity and promotion of tumor necrosis factor-α (TNF-α)-induced cell death. However, it remains unknown whether this regulation is also applicable to fibroblastoma cells. Methods Intracellular cAMP was determined in L929 fibroblastoma cells after treatment of the cells with various cAMP elevation agents. Effects of cAMP in the presence or absence of the RNA synthesis inhibitor actinomycin D or small interfering RNAs (siRNAs) against CREB on TNF-α-induced cell death in L929 cells were measured by propidium iodide (PI) staining and subsequent flow cytomety. The activation of p38 and c-Jun N-terminal protein kinase (JNK), another member of MAPK superfamily, was analyzed by immunoblotting. JNK selective inhibitor D-JNKi1 and p38 selective inhibitor SB203580 were included to examine the roles of JNK and p38 in this process. The expression of DLC or other mediators of cAMP was analyzed by immunoblotting. After ectopic expression of DLC with a transfection marker GFP, effects of cAMP on TNF-α-induced cell death in GFP+ cells were measured by PI staining and subsequent flow cytomety. Results Elevation of cAMP suppressed TNF-α-induced necrotic cell death in L929 fibroblastoma cells via CREB-mediated transcription. The pro-survival role of cAMP was associated with selective unresponsiveness of L929 cells to the inhibition of p38 activation by cAMP, even though cAMP significantly inhibited the activation of JNK under the same conditions. Further exploration revealed that the induction of DLC, the major mediator of p38 inhibition by cAMP, was impaired in L929 cells. Enforced inhibition of p38 activation by using p38 specific inhibitor or ectopic expression of DLC reversed the protection of L929 cells by cAMP from TNF-α-induced cell death. Conclusion These data suggest that the lack of a pro-apoptotic pathway in tumor cells leads to a net survival effect of cAMP.
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Affiliation(s)
- Jing Wang
- Department of Molecular Immunology, Institute of Basic Medical Sciences, Beijing, PR China
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171
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Yu Z, Kong Q, Kone BC. CREB trans-activation of disruptor of telomeric silencing-1 mediates forskolin inhibition of CTGF transcription in mesangial cells. Am J Physiol Renal Physiol 2010; 298:F617-24. [PMID: 20053791 DOI: 10.1152/ajprenal.00636.2009] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Connective tissue growth factor (CTGF) participates in diverse fibrotic processes including glomerulosclerosis. The adenylyl cyclase agonist forskolin inhibits CTGF expression in mesangial cells by unclear mechanisms. We recently reported that the histone H3K79 methyltransferase disruptor of telomeric silencing-1 (Dot1) suppresses CTGF gene expression in collecting duct cells (J Clin Invest 117: 773-783, 2007) and HEK 293 cells (J Biol Chem In press). In the present study, we characterized the involvement of Dot1 in mediating the inhibitory effect of forskolin on CTGF transcription in mouse mesangial cells. Overexpression of Dot1 or treatment with forskolin dramatically suppressed basal CTGF mRNA levels and CTGF promoter-luciferase activity, while hypermethylating H3K79 in chromatin associated with the CTGF promoter. siRNA knockdown of Dot1 abrogated the inhibitory effect of forskolin on CTGF mRNA expression. Analysis of the Dot1 promoter sequence identified a CREB response element (CRE) at -384/-380. Overexpression of CREB enhanced forskolin-stimulated Dot1 promoter activity. A constitutively active CREB mutant (CREB-VP16) strongly induced Dot1 promoter-luciferase activity, whereas overexpression of CREBdLZ-VP16, which lacks the CREB DNA-binding domain, abolished this activation. Mutation of the -384/-380 CRE resulted in 70% lower levels of Dot1 promoter activity. ChIP assays confirmed CREB binding to the Dot1 promoter in chromatin. We conclude that forskolin stimulates CREB-mediated trans-activation of the Dot1 gene, which leads to hypermethylation of histone H3K79 at the CTGF promoter, and inhibition of CTGF transcription. These data are the first to describe regulation of the Dot1 gene, and disclose a complex network of genetic and epigenetic controls on CTGF transcription.
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Affiliation(s)
- Zhiyuan Yu
- Department of Medicine, Division of Renal Diseases and Hypertension, The University of Texas Medical School at Houston, Houston, Texas 77006, USA
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172
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Hill JW. Gene Expression and the Control of Food Intake by Hypothalamic POMC/CART Neurons. OPEN NEUROENDOCRINOLOGY JOURNAL (ONLINE) 2010; 3:21-27. [PMID: 28042349 PMCID: PMC5201111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Neurons that express pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) in the arcuate nucleus of the hypothalamus suppress feeding and increase energy expenditure in response to circulating adiposity signals such as leptin. Alterations in gene expression may lead to long term modification of this circuit and alterations in body weight. Therefore, understanding how gene expression in these neurons is controlled is crucial to forming a complete picture of the central management of energy balance. This review outlines the heterogeneity of arcuate POMC/CART neurons, describes our current understanding of CART and POMC gene transcription in these neurons, and suggests future directions for extending the field.
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Affiliation(s)
- Jennifer W. Hill
- Address correspondence to this author at the University of Toledo College of Medicine; Health Science Campus, 3000 Arlington Ave, Block Health Science Bldg., CeDER, Toledo, OH 43614-2598, USA; Tel: 419-383-4183; Fax: 419-383-2871;
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173
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Wen DQ, Zhang YY, Lv LP, Zhou XP, Yan F, Ma P, Xu JB. Human cytomegalovirus-encoded chemokine receptor homolog US28 stimulates the major immediate early gene promoter/enhancer via the induction of CREB. J Recept Signal Transduct Res 2009; 29:266-73. [PMID: 19772393 DOI: 10.1080/10799890903178141] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The major immediate early (MIE) gene of cytomegalovirus plays a key role in determining the activation and replication of cytomegalovirus, which represents the most important event signaling the onset of virus-induced disease relapse. The viral-encoded chemokine receptor homolog US28 can constitutively activate many cellular transcription factors, which can bind to the promoter/enhancer of the MIE gene and activate its transcription. Using reporter gene assays in HEK293 cells, we found that US28 enhanced the transcription efficiency of MIE and other genes via cAMP response element-binding protein (CREB). Inhibition of CREB partially blocked the effect of US28, whereas forskolin enhanced this effect. There was a direct correlation between CREB and transcription of MIE gene. These data, together with the broad-spectrum effect of cellular transcription factors, suggest that US28 may be involved in the very early transcription of the host cell during virus activation.
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Affiliation(s)
- Dong-Qing Wen
- Beijing Institute of Transfusion Medicine, Beijing 100850, P R China
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174
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Prostaglandin E2 activates cAMP response element-binding protein in glioma cells via a signaling pathway involving PKA-dependent inhibition of ERK. Prostaglandins Other Lipid Mediat 2009; 91:18-29. [PMID: 20015475 DOI: 10.1016/j.prostaglandins.2009.12.002] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 12/03/2009] [Accepted: 12/07/2009] [Indexed: 12/13/2022]
Abstract
Prostaglandin E(2) (PGE(2)) plays a critical role in influencing the biological behavior of tumor cells. We previously demonstrated that PGE(2) stimulates human glioma cell growth via activation of protein kinase A (PKA) type II. This study was undertaken to further elucidate the intracellular pathways activated by PGE(2) downstream to PKA. Stimulation of U87-MG glioma cells with PGE(2) increased phosphorylation of the cyclic-AMP response element (CRE) binding protein CREB at Ser-133 and CREB-driven transcription in a dose- and time-dependent manner. Expression of dominant CREB constructs that interfere with CREB phosphorylation at Ser-133 or with its binding to the CRE site markedly decreased PGE(2)-induced CREB activation. Inhibition of PKA by H-89 or expression of a dominant negative PKA construct attenuated PGE(2)-induced CREB activation. Moreover, inhibition of PKA type II decreased PGE(2)-induced CREB-dependent transcription by 45% compared to vehicle-treated cells. To investigate the involvement of additional signaling pathways, U87-MG cells were pretreated with wortmannin or LY294002 to inhibit the PI3-kinase/AKT pathway. Both inhibitors had no effect on PGE(2)-induced CREB phosphorylation and transcriptional activity, suggesting that PGE(2) activates CREB in a PI3-kinase/AKT independent manner. Challenge of U87-MG cells with PGE(2), at concentrations that induced maximal CREB activation, or with forskolin inhibited extracellular signal-regulated kinase (ERK) phosphorylation. Pretreatment of U87-MG cells with the ERK inhibitor PD98059, accentuated ERK inhibition and increased CREB phosphorylation at Ser-133 and CREB-driven transcription stimulated by PGE(2), suggesting that inhibition of ERK contributes to PGE(2)-induced CREB activation. Inhibition of ERK by PGE(2) or by forskolin was rescued by treatment of cells with H-89 or by the dominant negative PKA construct. Moreover, PGE(2) or forskolin inhibited phosphorylation of Raf-1 phosphorylation at Ser-338. Challenge of U87-MG cells with 11-deoxy-PGE(1) increased CREB-driven transcription and stimulated cell growth, while other PGE(2) analogues had no effect. Together our results reveal a novel signaling pathway whereby PGE(2) signals through PKA to inhibit ERK and increase CREB transcriptional activity.
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175
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Lam BYH, Zhang W, Ng DCH, Maruthappu M, Roderick HL, Chawla S. CREB-dependent Nur77 induction following depolarization in PC12 cells and neurons is modulated by MEF2 transcription factors. J Neurochem 2009; 112:1065-73. [PMID: 19968756 DOI: 10.1111/j.1471-4159.2009.06521.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Expression of the nuclear orphan receptor gene Nur77 in neuronal cells is induced by activity-dependent increases in intracellular Ca2+ ions. Ca2+ responsiveness of the Nur77 gene has been attributed to two distinct DNA regulatory regions that recruit the transcription factors cAMP response element binding protein (CREB) and myocyte enhancer factor-2 (MEF2). Here we used dominant interfering and constitutively active mutants of CREB and MEF2 proteins to assess their relative contribution to depolarization-induced Nur77 expression in undifferentiated PC12 cells and hippocampal neurons. We show that while CREB is necessary for Ca2+-activated Nur77 expression MEF2 functions to modulate CREB-dependent Nur77 expression by acting as a repressor in quiescent cells.
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176
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Hayakawa K, Nakajima S, Hiramatsu N, Okamura M, Huang T, Saito Y, Tagawa Y, Tamai M, Takahashi S, Yao J, Kitamura M. ER stress depresses NF-kappaB activation in mesangial cells through preferential induction of C/EBP beta. J Am Soc Nephrol 2009; 21:73-81. [PMID: 19875812 DOI: 10.1681/asn.2009040432] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Modest induction of endoplasmic reticulum (ER) stress confers resistance to inflammation in glomeruli. Recently, we found that ER stress leads to mesangial insensitivity to cytokine-induced activation of NF-kappaB, but the underlying mechanisms are incompletely understood. ER stress can trigger expression of CCAAT/enhancer-binding proteins (C/EBPs), which interact with transcription factors including NF-kappaB. Here, we investigated a role for C/EBPs in the ER stress-induced resistance to cytokines. Mesangial cells preferentially induced C/EBPbeta after exposure to thapsigargin or tunicamycin; induction of C/EBPdelta was modest and transient, and expression of C/EBPalpha was absent. The induction of C/EBPbeta correlated with accumulation of C/EBPbeta protein and enhanced transcriptional activity of C/EBP. Overexpression of C/EBPbeta markedly suppressed TNF-alpha-induced activation of NF-kappaB, independent of its transacting potential. Knockdown of C/EBPbeta by small interfering RNA reversed the suppressive effect of ER stress on NF-kappaB. In vivo, preconditioning of mice with ER stress induced renal C/EBPbeta and suppressed NF-kappaB-dependent gene expression in response to LPS. Using dominant negative mutants and null mutants for individual branches of the unfolded protein response, we identified the RNA-dependent protein kinase-like ER kinase (PERK) and the inositol-requiring ER-to-nucleus signal kinase 1 (IRE1) pathways as the unfolded protein response responsible for ER stress-induced C/EBPbeta. These results suggest that ER stress blunts cytokine-triggered activation of NF-kappaB, in part through PERK- and IRE1-mediated preferential induction of C/EBPbeta.
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Affiliation(s)
- Kunihiro Hayakawa
- Department of Molecular Signaling, University of Yamanashi, Shimokato 1110, Chuo, Yamanashi 409-3898, Japan
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177
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Falktoft B, Georg B, Fahrenkrug J. Signaling pathways in PACAP regulation of VIP gene expression in human neuroblastoma cells. Neuropeptides 2009; 43:387-96. [PMID: 19712974 DOI: 10.1016/j.npep.2009.08.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2009] [Revised: 07/16/2009] [Accepted: 08/04/2009] [Indexed: 11/30/2022]
Abstract
Ganglia expressing the neuropeptide pituitary adenylate cyclase-activating polypeptide (PACAP) innervate vasoactive intestinal peptide (VIP) containing neurons suggesting a role of PACAP in regulating VIP expression. Human NB-1 neuroblastoma cells were applied to study PACAP regulated VIP gene expression aiming to identify the receptor and the signaling proteins involved. The PACAP receptor subtype PAC1 induced VIP gene expression as (i) PACAP and the PAC1 receptor agonist maxadilan were equally efficient and approximately 200-fold more potent than VIP, and (ii) PACAP6-38 and PG99-465, antagonists of PAC1 and VPAC2 receptors, respectively, abolished and did not affect the PACAP-induced VIP mRNA expression, respectively. A pivotal role of PKA was implicated in addition to partial involvement of PKC and ERK1/2 in PACAP-induced VIP gene expression as H-89, Bisindolylmaleimide I (BIS), Gö6976 and U0126 attenuated the VIP mRNA expression by 93%, 58%, 58% and 40%, respectively. PACAP modulated the phosphorylation of ERK1/2 (pERK1/2) and CREB/ATF-1 (pCREB/ATF-1) concomitant with a translocation of PKA to the nucleus. Inhibition of conventional PKC isoforms and MEK1/2 completely abolished pERK1/2 without affecting PACAP induced pCREB/ATF-1. In contrast, inhibiting PKA attenuated PACAP induced pCREB/ATF-1. PACAP also enhanced the FOS gene expression and individual presence of H-89, BIS, Gö6976 and U0126 partially attenuated the PACAP induced FOS mRNA expression. Combining the kinase inhibitors completely suppressed the PACAP induced FOS mRNA expression. Immunoblotting confirmed expression of FOS protein upon addition of PACAP, which was diminished by impairment of PKC, ERK1/2 and PKA activities. The resemblance of the signaling pathways involving concomitant activities of PKC, ERK1/2 and PKA in PACAP regulation of the FOS and VIP gene expressions suggest for the first time a role of FOS in PACAP-induced VIP gene expression in human NB-1 neuroblastoma cells.
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Affiliation(s)
- Birgitte Falktoft
- Department of Clinical Biochemistry, Bispebjerg Hospital, Bispebjerg Bakke 23, DK-2400 Copenhagen, Denmark.
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178
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Tinsley CJ, Narduzzo KE, Ho JW, Barker GR, Brown MW, Warburton EC. A role for calcium-calmodulin-dependent protein kinase II in the consolidation of visual object recognition memory. Eur J Neurosci 2009; 30:1128-39. [PMID: 19735285 DOI: 10.1111/j.1460-9568.2009.06917.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The aim was to investigate the role of calcium-calmodulin-dependent protein kinase (CAMK)II in object recognition memory. The performance of rats in a preferential object recognition test was examined after local infusion of the CAMKII inhibitors KN-62 or autocamtide-2-related inhibitory peptide (AIP) into the perirhinal cortex. KN-62 or AIP infused after acquisition impaired memory tested at 24 h, indicating an involvement of CAMKII in the consolidation of recognition memory. Memory was impaired when KN-62 was infused at 20 min after acquisition or when AIP was infused at 20, 40, 60 or 100 min after acquisition. The time-course of CAMKII activation in rats was further examined by immunohistochemical staining for phospho-CAMKII(Thre286)alpha at 10, 40, 70 and 100 min following the viewing of novel and familiar images. At 70 min, processing novel images resulted in more phospho-CAMKII(Thre286)alpha-stained neurons in the perirhinal cortex than did the processing of familiar images, consistent with the viewing of novel images increasing the activity of CAMKII at this time. This difference was eliminated by prior infusion of AIP. These findings establish that CAMKII is active within the perirhinal region between approximately 20 and 100 min following learning and then returns to baseline. Thus, increased CAMKII activity is essential for the consolidation of long-term object recognition memory but continuation of that increased activity throughout the 24 h memory delay is not necessary for maintenance of the memory.
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Affiliation(s)
- C J Tinsley
- Department of Anatomy, Medical Research Council Centre for Synaptic Plasticity, Bristol University, University Walk, Bristol, UK.
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179
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Qi YM, Lei T, Zhou L, Chen XD, Long QQ, Long H, Jin D, Gan L, Yang ZQ. Genomic organization, alternative splicing and tissues expression of porcine CREB3L4 gene. Mol Biol Rep 2009; 36:1881-1888. [PMID: 18982425 DOI: 10.1007/s11033-008-9394-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2008] [Accepted: 10/17/2008] [Indexed: 10/21/2022]
Abstract
CREB3L4 (cAMP response element binding protein3 like 4) belongs to mammalian CREB/ATF subfamily transcription factors featuring a unique putative transmembrane domain lined to the bZIP region in their C-terminals. We report here the cloning of porcine CREB3L4 and its alternative splicing variant. The open reading frame of normal CREB3L4 covers 1,188 bp and encodes a 395-amino acid polypeptide, whereas its variant encodes a C-terminal truncated protein comprising only 271 amino acids. The genomic sequence of porcine CREB3L4 spans approximately 6 kb consisted of ten exons and nine introns, and maps closely to Jumping translocation breakpoint gene in a head-to-head manner on the q arm of Sus Scrofa chromosome 4. Tissue expression analysis by RT-PCR indicates that normal porcine CREB3L4 is ubiquitously expressed with relatively high abundance in stomach, liver, cerebellum, and is a predominant form in various tissues, whereas the splicing variant is expressed at extremely low level in all examined tissues. Our study will lay the groundwork for the further investigation on the physiological function of CREB3L4 in pig models.
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Affiliation(s)
- Y M Qi
- College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, People's Republic of China
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180
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CREB: A Key Regulator of Normal and Neoplastic Hematopoiesis. Adv Hematol 2009; 2009:634292. [PMID: 19960054 PMCID: PMC2778441 DOI: 10.1155/2009/634292] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2009] [Accepted: 05/30/2009] [Indexed: 11/17/2022] Open
Abstract
The cAMP response element-binding protein (CREB) is a nuclear transcription factor downstream of cell surface receptors and mitogens that is critical for normal and neoplastic hematopoiesis. Previous work from our laboratory demonstrated that a majority of patients with acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL) overexpress CREB in the bone marrow. To understand the role of CREB in leukemogenesis, we examined the biological effect of CREB overexpression on primary leukemia cells, leukemia cell lines, and CREB overexpressing transgenic mice. Our results demonstrated that CREB overexpression leads to an increase in cellular proliferation and survival. Furthermore, CREB transgenic mice develop a myeloproliferative disorder with aberrant myelopoiesis in both the bone marrow and spleen. Additional research from other groups has shown that the expression of the cAMP early inducible repressor (ICER), a CREB repressor, is also deregulated in leukemias. And, miR-34b, a microRNA that negative regulates CREB expression, is expressed at lower levels in myeloid leukemia cell lines compared to that of healthy bone marrow. Taken together, these data suggest that CREB plays a role in cellular transformation. The data also suggest that CREB-specific signaling pathways could possibly serve as potential targets for therapeutic intervention.
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181
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GABA-cAMP response element-binding protein signaling regulates maturation and survival of newly generated neurons in the adult hippocampus. J Neurosci 2009; 29:7966-77. [PMID: 19553437 DOI: 10.1523/jneurosci.1054-09.2009] [Citation(s) in RCA: 265] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Survival and integration of new neurons in the hippocampal circuit are rate-limiting steps in adult hippocampal neurogenesis. Neuronal network activity is a major regulator of these processes, yet little is known about the respective downstream signaling pathways. Here, we investigate the role of cAMP response element-binding protein (CREB) signaling in adult hippocampal neurogenesis. CREB is activated in new granule neurons during a distinct developmental period. Loss of CREB function in a cell-autonomous manner impairs dendritic development, decreases the expression of the neurogenic transcription factor NeuroD and of the neuronal microtubule-associated protein, doublecortin (DCX), and compromises the survival of newborn neurons. In addition, GABA-mediated excitation regulates CREB activation at early developmental stages. Importantly, developmental defects after loss of GABA-mediated excitation can be compensated by enhanced CREB signaling. These results indicate that CREB signaling is a central pathway in adult hippocampal neurogenesis, regulating the development and survival of new hippocampal neurons downstream of GABA-mediated excitation.
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182
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Selective inhibition of hypoxia-inducible factor (HIF) prolyl-hydroxylase 1 mediates neuroprotection against normoxic oxidative death via HIF- and CREB-independent pathways. J Neurosci 2009; 29:8828-38. [PMID: 19587290 DOI: 10.1523/jneurosci.1779-09.2009] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Oxidative stress contributes to tissue injury in conditions ranging from cardiovascular disease to stroke, spinal cord injury, neurodegeneration, and perhaps even aging. Yet the efficacy of antioxidants in human disease has been mixed at best. We need a better understanding of the mechanisms by which established antioxidants combat oxidative stress. Iron chelators are well established inhibitors of oxidative death in both neural and non-neural tissues, but their precise mechanism of action remains elusive. The prevailing but not completely substantiated view is that iron chelators prevent oxidative injury by suppressing Fenton chemistry and the formation of highly reactive hydroxyl radicals. Here, we show that iron chelation protects, rather unexpectedly, by inhibiting the hypoxia-inducible factor prolyl 4-hydroxylase isoform 1 (PHD1), an iron and 2-oxoglutarate-dependent dioxygenase. PHD1 and its isoforms 2 and 3 are best known for stabilizing transcriptional regulators involved in hypoxic adaptation, such as HIF-1alpha and cAMP response element-binding protein (CREB). Yet we find that global hypoxia-inducible factor (HIF)-PHD inhibition protects neurons even when HIF-1alpha and CREB are directly suppressed. Moreover, two global HIF-PHD inhibitors continued to be neuroprotective even in the presence of diminished HIF-2alpha levels, which itself increases neuronal susceptibility to oxidative stress. Finally, RNA interference to PHD1 but not isoforms PHD2 or PHD3 prevents oxidative death, independent of HIF activation. Together, these studies suggest that iron chelators can prevent normoxic oxidative neuronal death through selective inhibition of PHD1 but independent of HIF-1alpha and CREB; and that HIF-2alpha, not HIF-1alpha, regulates susceptibility to normoxic oxidative neuronal death.
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183
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Bipartite functions of the CREB co-activators selectively direct alternative splicing or transcriptional activation. EMBO J 2009; 28:2733-47. [PMID: 19644446 DOI: 10.1038/emboj.2009.216] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 07/07/2009] [Indexed: 12/31/2022] Open
Abstract
The CREB regulated transcription co-activators (CRTCs) regulate many biological processes by integrating and converting environmental inputs into transcriptional responses. Although the mechanisms by which CRTCs sense cellular signals are characterized, little is known regarding how CRTCs contribute to the regulation of cAMP inducible genes. Here we show that these dynamic regulators, unlike other co-activators, independently direct either pre-mRNA splice-site selection or transcriptional activation depending on the cell type or promoter context. Moreover, in other scenarios, the CRTC co-activators coordinately regulate transcription and splicing. Mutational analyses showed that CRTCs possess distinct functional domains responsible for regulating either pre-mRNA splicing or transcriptional activation. Interestingly, the CRTC1-MAML2 oncoprotein lacks the splicing domain and is incapable of altering splice-site selection despite robustly activating transcription. The differential usage of these distinct domains allows CRTCs to selectively mediate multiple facets of gene regulation, indicating that co-activators are not solely restricted to coordinating alternative splicing with increase in transcriptional activity.
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184
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Seoane A, Massey PV, Keen H, Bashir ZI, Brown MW. L-type voltage-dependent calcium channel antagonists impair perirhinal long-term recognition memory and plasticity processes. J Neurosci 2009; 29:9534-44. [PMID: 19641116 PMCID: PMC6666523 DOI: 10.1523/jneurosci.5199-08.2009] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2008] [Revised: 06/05/2009] [Accepted: 06/08/2009] [Indexed: 01/22/2023] Open
Abstract
The perirhinal cortex of the temporal lobe is essential for the familiarity discrimination component of recognition memory. In view of the importance of changes in calcium ion concentration for synaptic plasticity, the present study examined the effects of L-type voltage-dependent calcium channel (VDCC) antagonism on rat perirhinal-based familiarity discrimination processes and plasticity including long-term depression (LTD), long-term potentiation (LTP), and depotentiation. Single doses of three different types of L-type VDCC antagonists, verapamil, diltiazem, and nifedipine, administered systemically, or verapamil administered locally into the perirhinal cortex, impaired acquisition of long-term (24 h) but not shorter-term (20 min) recognition memory. L-type VDCC antagonism also disrupted memory retrieval after 24 h but not 20 min. Differential neuronal activation produced by viewing novel or familiar visual stimuli was measured by Fos expression. L-type VDCC antagonism by verapamil in perirhinal cortex during memory acquisition disrupted the normal pattern of differential Fos expression, so paralleling the antagonist-induced memory impairment. In slices of perirhinal cortex maintained in vitro, verapamil was without effect on baseline excitability or LTP but blocked LTD and depotentiation. The consistency of effects across the behavioral and cellular levels of analysis provides strong evidence for the involvement of perirhinal L-type VDCCs in long-term recognition memory processes.
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Affiliation(s)
- Ana Seoane
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Peter V. Massey
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Hannah Keen
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Zafar I. Bashir
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, United Kingdom
| | - Malcolm W. Brown
- Medical Research Council Centre for Synaptic Plasticity, Department of Anatomy, University of Bristol, Bristol BS8 1TD, United Kingdom
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185
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Choi YS, Lee B, Cho HY, Reyes IB, Pu XA, Saido TC, Hoyt KR, Obrietan K. CREB is a key regulator of striatal vulnerability in chemical and genetic models of Huntington's disease. Neurobiol Dis 2009; 36:259-68. [PMID: 19632326 DOI: 10.1016/j.nbd.2009.07.014] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Revised: 06/26/2009] [Accepted: 07/15/2009] [Indexed: 11/19/2022] Open
Abstract
Evidence of dysregulation of the CREB/CRE transcriptional pathway in animal models of Huntington's disease (HD) suggests that strategies designed to augment CRE-mediated transcription may be of therapeutic value. Here, we investigated the consequences of CREB activation and repression in chemical and transgenic mouse models of HD. In the 3-nitropropionic acid (3-NP) model, CREB phospho-activation in the striatum was potently repressed within the neurotoxic "core" region prior to cell death. Conversely, marked expression of phospho-CREB, as well the CREB-regulated cytoprotective gene Bcl-2, was detected in the "penumbral" region. To examine potential contributory roles for the CREB/CRE transcriptional pathway in striatal degeneration, we used both CREB loss- (A-CREB) and gain- (VP16-CREB) of-function transgenic mouse strains. 3-NP-induced striatal lesion size and motor dysfunction were significantly increased in A-CREB mice compared to controls. Conversely, striatal damage and motor deficits were diminished in VP16-CREB mice. Furthermore, transgenic A-CREB significantly accelerated motor impairment in the YAC128 mouse model of HD. Together, these results indicate that CREB functionality is lost during the early stages of striatal cell stress and that the repression of CREB-mediated transcription contributes to the pathogenic process.
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Affiliation(s)
- Yun-Sik Choi
- Department of Neuroscience, Ohio State University, Columbus, OH 43210, USA
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186
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Johnson MA, Ables JL, Eisch AJ. Cell-intrinsic signals that regulate adult neurogenesis in vivo: insights from inducible approaches. BMB Rep 2009; 42:245-59. [PMID: 19470237 DOI: 10.5483/bmbrep.2009.42.5.245] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The process by which adult neural stem cells generate new and functionally integrated neurons in the adult mammalian brain has been intensely studied, but much more remains to be discovered. It is known that neural progenitors progress through distinct stages to become mature neurons, and this progression is tightly controlled by cell-cell interactions and signals in the neurogenic niche. However, less is known about the cell-intrinsic signaling required for proper progression through stages of adult neurogenesis. Techniques have recently been developed to manipulate genes specifically in adult neural stem cells and progenitors in vivo, such as the use of inducible transgenic mice and viral-mediated gene transduction. A critical mass of publications utilizing these techniques has been reached, making it timely to review which molecules are now known to play a cell-intrinsic role in regulating adult neurogenesis in vivo. By drawing attention to these isolated molecules (e.g. Notch), we hope to stimulate a broad effort to understand the complex and compelling cascades of intrinsic signaling molecules important to adult neurogenesis. Understanding this process opens the possibility of understanding brain functions subserved by neurogenesis, such as memory, and also of harnessing neural stem cells for repair of the diseased and injured brain.
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Affiliation(s)
- Madeleine A Johnson
- Department of Psychiatry, University of Texas Southwestern Medical Center, Dallas, Texas, 75390-9070, USA
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187
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Jeng YJ, Soloff MS. Characterization of the cyclic adenosine monophosphate target site in the oxytocin receptor gene in rabbit amnion. Biol Reprod 2009; 81:473-9. [PMID: 19439725 DOI: 10.1095/biolreprod.109.077941] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Oxytocin (OXT) is a potent stimulator of prostaglandin E(2) (PGE(2)) synthesis by rabbit amnion cells obtained near the end of pregnancy. Coincident with a marked increase in sensitivity of PGE(2) synthesis to OXT, the concentration of OXT receptors (OXTRs) is abruptly upregulated about 200-fold at term. This increase can be mimicked in preterm amnion cells in primary culture by the synergistic action of agents that increase cAMP synthesis and by glucocorticoids. To elucidate the mechanism of cAMP action, we cloned the rabbit OXTR gene and isolated a 200-base pair (bp) forskolin-responsive region about 4.7 kilobase upstream from the transcriptional start site using transient transfection assays. This region corresponds to a DNase I-hypersensitive site that appears in amnion tissue only near the end of pregnancy, when OXTRs are upregulated. The effects of forskolin were mediated in part by cAMP response element binding protein (CREB), as coexpression of reporter constructs with dominant negative CREB inhibited reporter expression. In addition, CREB was cross-linked to sites in the 200-bp region only in chromatin isolated from cells near the end of pregnancy, as demonstrated by chromatin immunoprecipitation (ChIP). Because the transient transfection results are consistent with work using tissue extracts (DNase I hypersensitivity and ChIP), we conclude that cAMP, acting through a specific upstream CREB binding site, is critical for the physiological upregulation of OXTRs in the amnion at the end of gestation.
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Affiliation(s)
- Yow-Jiun Jeng
- Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, Texas 77555-1062, USA
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188
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Rozenberg J, Rishi V, Orosz A, Moitra J, Glick A, Vinson C. Inhibition of CREB function in mouse epidermis reduces papilloma formation. Mol Cancer Res 2009; 7:654-64. [PMID: 19435810 DOI: 10.1158/1541-7786.mcr-08-0011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We used a double transgenic tetracycline system to conditionally express A-CREB, a dominant negative protein that prevents the DNA binding and function of cAMP-responsive element binding protein (CREB) family members, in mouse basal epidermis using the keratin 5 promoter. There was no phenotype in the adult. However, following a 7,12-dimethylbenz(a)anthracene (DMBA)/phorbol-12-myristate-13-acetate two-stage skin carcinogenesis experiment, A-CREB-expressing epidermis develop 5-fold fewer papillomas than wild-type controls. However, A-CREB expression one month after DMBA treatment does not prevent papilloma formation, suggesting that CREB functions at an early stage of papilloma formation. Oncogenic H-Ras genes with A-->T mutations in codon 61 were found in wild-type skin but not in A-CREB-expressing skin 2 days after DMBA treatment, suggesting that A-CREB either prevents DMBA mutagenesis or kills oncogenic H-Ras cells. In primary keratinocyte cultures, A-CREB expression induced apoptosis of v-Ras(Ha)-infected cells and suppressed the expression of cell cycle proteins cyclin B1 and cyclin D1. These results suggest that inhibiting CREB function is a valuable cancer prevention strategy.
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Affiliation(s)
- Julian Rozenberg
- Laboratory of Metabolism, National Cancer Institute, NIH, 37 Convent Drive, Room 2D24, Bethesda, MD 20892, USA
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189
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Lafferty-Whyte K, Cairney CJ, Jamieson NB, Oien KA, Keith WN. Pathway analysis of senescence-associated miRNA targets reveals common processes to different senescence induction mechanisms. Biochim Biophys Acta Mol Basis Dis 2009; 1792:341-52. [DOI: 10.1016/j.bbadis.2009.02.003] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 02/02/2009] [Accepted: 02/03/2009] [Indexed: 01/07/2023]
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190
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Coordination of PGC-1beta and iron uptake in mitochondrial biogenesis and osteoclast activation. Nat Med 2009; 15:259-66. [PMID: 19252502 DOI: 10.1038/nm.1910] [Citation(s) in RCA: 317] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Accepted: 01/05/2009] [Indexed: 12/16/2022]
Abstract
Osteoclasts are acid-secreting polykaryons that have high energy demands and contain abundant mitochondria. How mitochondrial biogenesis is integrated with osteoclast differentiation is unknown. We found that the transcription of Ppargc1b, which encodes peroxisome proliferator-activated receptor-gamma coactivator 1beta (PGC-1beta), was induced during osteoclast differentiation by cAMP response element-binding protein (CREB) as a result of reactive oxygen species. Knockdown of Ppargc1b in vitro inhibited osteoclast differentiation and mitochondria biogenesis, whereas deletion of the Ppargc1b gene in mice resulted in increased bone mass due to impaired osteoclast function. We also observed defects in PGC-1beta-deficient osteoblasts. Owing to the heightened iron demand in osteoclast development, transferrin receptor 1 (TfR1) expression was induced post-transcriptionally via iron regulatory protein 2. TfR1-mediated iron uptake promoted osteoclast differentiation and bone-resorbing activity, associated with the induction of mitochondrial respiration, production of reactive oxygen species and accelerated Ppargc1b transcription. Iron chelation inhibited osteoclastic bone resorption and protected against bone loss following estrogen deficiency resulting from ovariectomy. These data establish mitochondrial biogenesis orchestrated by PGC-1beta, coupled with iron uptake through TfR1 and iron supply to mitochondrial respiratory proteins, as a fundamental pathway linked to osteoclast activation and bone metabolism.
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191
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Qi L, Saberi M, Zmuda E, Wang Y, Altarejos J, Zhang X, Dentin R, Hedrick S, Bandyopadhyay G, Hai T, Olefsky J, Montminy M. Adipocyte CREB promotes insulin resistance in obesity. Cell Metab 2009; 9:277-86. [PMID: 19254572 PMCID: PMC2730923 DOI: 10.1016/j.cmet.2009.01.006] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 10/20/2008] [Accepted: 01/14/2009] [Indexed: 10/21/2022]
Abstract
Increases in adiposity trigger metabolic and inflammatory changes that interfere with insulin action in peripheral tissues, culminating in beta cell failure and overt diabetes. We found that the cAMP Response Element Binding protein (CREB) is activated in adipose cells under obese conditions, where it promotes insulin resistance by triggering expression of the transcriptional repressor ATF3 and thereby downregulating expression of the adipokine hormone adiponectin as well as the insulin-sensitive glucose transporter 4 (GLUT4). Transgenic mice expressing a dominant-negative CREB transgene in adipocytes displayed increased whole-body insulin sensitivity in the contexts of diet-induced and genetic obesity, and they were protected from the development of hepatic steatosis and adipose tissue inflammation. These results indicate that adipocyte CREB provides an early signal in the progression to type 2 diabetes.
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Affiliation(s)
- Ling Qi
- Laboratories for Peptide Biology, Salk Institute for Biological Studies, La Jolla, CA 92037, USA
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192
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Jancic D, Lopez de Armentia M, Valor LM, Olivares R, Barco A. Inhibition of cAMP response element-binding protein reduces neuronal excitability and plasticity, and triggers neurodegeneration. ACTA ACUST UNITED AC 2009; 19:2535-47. [PMID: 19213815 DOI: 10.1093/cercor/bhp004] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The cAMP-responsive element-binding protein (CREB) pathway has been involved in 2 major cascades of gene expression regulating neuronal function. The first one presents CREB as a critical component of the molecular switch that controls long-lasting forms of neuronal plasticity and learning. The second one relates CREB to neuronal survival and protection. To investigate the role of CREB-dependent gene expression in neuronal plasticity and survival in vivo, we generated bitransgenic mice expressing A-CREB, an artificial peptide with strong and broad inhibitory effect on the CREB family, in forebrain neurons in a regulatable manner. The expression of A-CREB in hippocampal neurons impaired L-LTP, reduced intrinsic excitability and the susceptibility to induced seizures, and altered both basal and activity-driven gene expression. In the long-term, the chronic inhibition of CREB function caused severe loss of neurons in the CA1 subfield as well as in other brain regions. Our experiments confirmed previous findings in CREB-deficient mutants and revealed new aspects of CREB-dependent gene expression in the hippocampus supporting a dual role for CREB-dependent gene expression regulating intrinsic and synaptic plasticity and promoting neuronal survival.
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Affiliation(s)
- Dragana Jancic
- Instituto de Neurociencias de Alicante (Universidad Miguel Hernández-Consejo Superior de Investigaciones Científicas), Campus de Sant Joan, 03550 Alicante, Spain
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193
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Lee B, Cao R, Choi YS, Cho HY, Rhee AD, Hah CK, Hoyt KR, Obrietan K. The CREB/CRE transcriptional pathway: protection against oxidative stress-mediated neuronal cell death. J Neurochem 2009; 108:1251-65. [PMID: 19141071 DOI: 10.1111/j.1471-4159.2008.05864.x] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Formation of reactive oxygen and nitrogen species is a precipitating event in an array of neuropathological conditions. In response to excessive reactive oxygen species (ROS) levels, transcriptionally dependent mechanisms drive the up-regulation of ROS scavenging proteins which, in turn, limit the extent of brain damage. Here, we employed a transgenic approach in which cAMP-response element binding protein (CREB)-mediated transcription is repressed (via A-CREB) to examine the contribution of the CREB/cAMP response element pathway to neuroprotection and its potential role in limiting ROS toxicity. Using the pilocarpine-evoked repetitive seizure model, we detected a marked enhancement of cell death in A-CREB transgenic mice. Paralleling this, there was a dramatic increase in tyrosine nitration (a marker of reactive species formation) in A-CREB transgenic mice. In addition, inducible expression of peroxisome proliferator-activated receptor gamma coactivator-1alpha was diminished in A-CREB transgenic mice, as was activity of complex I of the mitochondrial electron transport chain. Finally, the neuroprotective effect of brain-derived neurotrophic factor (BDNF) against ROS-mediated cell death was abrogated by disruption of CREB-mediated transcription. Together, these data both extend our understanding of CREB functionality and provide in vivo validation for a model in which CREB functions as a pivotal upstream integrator of neuroprotective signaling against ROS-mediated cell death.
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Affiliation(s)
- Boyoung Lee
- Department of Neuroscience, Ohio State University, Columbus, 43210, USA
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194
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Takasaki I, Takarada S, Tatsumi S, Azegami A, Yasuda M, Fukuchi M, Tabuchi A, Kondo T, Tabuchi Y, Tsuda M. Extracellular adenosine 5'-triphosphate elicits the expression of brain-derived neurotrophic factor exon IV mRNA in rat astrocytes. Glia 2009; 56:1369-79. [PMID: 18649393 DOI: 10.1002/glia.20704] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A growing body of recent evidence indicates that ATP plays an important role in neuronal-glial communications. In this study, the authors demonstrated that extracellular ATP elicits the gene expression of brain-derived neurotrophic factor (BDNF), especially BDNF exon IV mRNA, in primary cultured rat cortical astrocytes but not in neurons. To investigate the mechanism by which ATP induces BDNF exon IV mRNA expression, the authors used immortalized astrocyte cell line RCG-12. ATP dose-dependently increased the expression of BDNF exon IV mRNA and activated BDNF promoter IV. P2Y receptor agonists (ADP and 2MeS-ADP) but not a P2X receptor agonist (alphabetaMeATP) induced the expression of BDNF exon IV mRNA. Moreover, ATP-induced BDNF exon IV mRNA upregulation was inhibited by a P2Y antagonist (MRS2179) but not by P2X antagonists (TNP-ATP and PPADS). These findings suggest the involvement of P2Y receptors in the ATP-induced transcription of the BDNF gene. Among the signal transduction inhibiters examined in this study, intracellular Ca(2+) chelator (BAPTA-AM) and Ca(2+)/calmodulin-dependent kinase (CaM kinase) inhibitors (KN-93 and W-7) attenuated ATP-induced BDNF exon IV mRNA upregulation. ATP transiently induced the phosphorylation of cAMP-responsive element-binding protein (CREB). ATP-induced CREB phosphorylation was repressed by P2Y antagonists, BAPTA-AM, and CaM kinase inhibitors. Overexpression of dominant negative CREB mutants reduced the activation of BDNF promoter IV and attenuated the upregulation of BDNF exon IV mRNA expression. These results suggest that ATP induces BDNF expression through P2Y receptor followed by the activation of CaM kinase and CREB in astrocytes. These mechanisms are likely to contribute to the enhancement of neuronal-glial networks.
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Affiliation(s)
- Ichiro Takasaki
- Division of Molecular Genetics Research, Life Science Research Center, University of Toyama, Toyama, Japan.
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195
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Mérot Y, Ferrière F, Gailhouste L, Huet G, Percevault F, Saligaut C, Flouriot G. Different outcomes of unliganded and liganded estrogen receptor-alpha on neurite outgrowth in PC12 cells. Endocrinology 2009; 150:200-11. [PMID: 18772239 DOI: 10.1210/en.2008-0449] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
A precise description of the mechanisms by which estrogen receptor-alpha (ERalpha) exerts its influences on cellular growth and differentiation is still pending. Here, we report that the differentiation of PC12 cells is profoundly affected by ERalpha. Importantly, depending upon its binding to 17beta-estradiol (17betaE2), ERalpha is found to exert different effects on pathways involved in nerve growth factor (NGF) signaling. Indeed, upon its stable expression in PC12 cells, unliganded ERalpha is able to partially inhibit the neurite outgrowth induced by NGF. This process involves a repression of MAPK and phosphatidylinositol 3-kinase/Akt signaling pathways, which leads to a negative regulation of markers of neuronal differentiation such as VGF and NFLc. This repressive action of unliganded ERalpha is mediated by its D domain and does not involve its transactivation and DNA-binding domains, thereby suggesting that direct transcriptional activity of ERalpha is not required. In contrast with this repressive action occurring in the absence of 17betaE2, the expression of ERalpha in PC12 cells allows 17betaE2 to potentiate the NGF-induced neurite outgrowth. Importantly, 17betaE2 has no impact on NGF-induced activity of MAPK and Akt signaling pathways. The mechanisms engaged by liganded ERalpha are thus unlikely to rely on an antagonism of the inhibition mediated by the unliganded ERalpha. Furthermore, 17betaE2 enhances NGF-induced response of VGF and NFLc neuronal markers in PC12 clones expressing ERalpha. This stimulatory effect of 17betaE2 requires the transactivation functions of ERalpha and its D domain, suggesting that an estrogen-responsive element-independent transcriptional mechanism is potentially relevant for the neuritogenic properties of 17betaE2 in ERalpha-expressing PC12 cells.
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Affiliation(s)
- Yohann Mérot
- Université de Rennes 1, Centre National de la Recherche Scientifique, Unité Mixte 6026, Equipe Récepteur des oestrogènes et destinée cellulaire, 35042 Rennes, France
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196
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Meyuhas R, Pikarsky E, Tavor E, Klar A, Abramovitch R, Hochman J, Lago TG, Honigman A. A Key role for cyclic AMP-responsive element binding protein in hypoxia-mediated activation of the angiogenesis factor CCN1 (CYR61) in Tumor cells. Mol Cancer Res 2008; 6:1397-409. [PMID: 18819928 DOI: 10.1158/1541-7786.mcr-07-2086] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Hypoxia is a prominent feature of solid tumors known to contribute to malignant progression and therapeutic resistance. Cancer cells adapt to hypoxia using various pathways, allowing tumors to thrive in a low oxygen state. Induction of new blood vessel formation via the secretion of proangiogenic factors is one of the main adaptive responses engaged by tumor cells under hypoxic conditions. Hypoxia-inducible factor 1 (HIF-1) is a transcription factor that plays a pivotal role in mediating such responses. In addition, several other transcription factors have also been implicated in hypoxic gene regulation, either independently or in cooperation with HIF-1. In this work, we show that the expression of the angiogenesis-related, immediate early gene CCN1 (formerly known as CYR61), considered to be involved in tumor growth and invasiveness, is enhanced upon hypoxia stress primarily in a protein kinase A and cyclic AMP-responsive element binding protein (CREB) and CRE-dependent manner in various cell lines. The hypoxia-mediated activation of the CCN1 promoter is independent of HIF-1 and HIF-2, as shown by small interfering RNA knockdown. We identify the cis element in the mouse CCN1 promoter responsible for CREB binding to be one of two partial CRE sites present in the promoter. Moreover, we report for the first time that CREB-mediated CCN1 transcription is enhanced in hypoxic regions of tumors in vivo. Identifying and characterizing the molecular mechanisms that govern the response of tumors to hypoxia may be instrumental to identify the tumors that will respond favorably to inhibition of angiogenesis and thus lead to the development of treatments that could complement hypoxia-inducing treatment modalities.
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Affiliation(s)
- Ronit Meyuhas
- Department of Virology, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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197
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Chen YL, Jian MH, Lin CC, Kang JC, Chen SP, Lin PC, Hung PJ, Chen JR, Chang WL, Lin SZ, Harn HJ. The induction of orphan nuclear receptor Nur77 expression by n-butylenephthalide as pharmaceuticals on hepatocellular carcinoma cell therapy. Mol Pharmacol 2008; 74:1046-58. [PMID: 18577687 DOI: 10.1124/mol.107.044800] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
N-butylidenephthalide (BP), isolated from the chloroform extract of Angelica sinensis, has been examined for its antitumor effects on glioblastoma multiforme brain tumors; however, little is known about its antitumor effects on hepatocellular carcinoma cells. Two hepatocellular carcinoma cell lines, HepG2 and J5, were treated with either N-butylidenephthalide or a vehicle, and cell viability and apoptosis were evaluated. Apoptosis-related mRNA and proteins expressed, including orphan receptor family Nurr1, NOR-1, and Nur77, were evaluated as well as the effect of N-butylidenephthalide in an in vivo xenograft model. N-butylidenephthalide caused growth inhibition of both the cell lines at 25 microg/ml. Furthermore, N-butylidenephthalide-induced apoptosis seems to be related to Nur77 translocation from nucleus to cytosol, which leads to cytochrome c release and caspase-3-dependent apoptosis. N-butylidenephthalide-related tumor apoptosis was associated with phosphatidylinositol 3-kinase/protein kinase B (AKT)/glycogen synthase kinase-3beta rather than the mitogen-activated protein kinase or protein kinase C pathway. Blockade of AKT activation enhanced proliferation inhibition and the induction of phosphor-Bcl-2 and Nur77 proteins. Besides, the increasing apoptosis by BP via transfection wild-type cAMP-response element-binding protein (CREB) into tumor cell was suppressed by dominant phosphorylation site mutation of CREB. This finding suggested CREB pathway was also partly involved in tumor apoptosis caused by BP. Administration of N-butylidenephthalide showed similar antitumoral effects in both HepG2 and J5 xenograft tumors. N-Butylidenephthalide induced apoptosis in hepatocellular carcinoma cells, both in vitro and in vivo, suggesting a potential clinical use of this compound for improving the prognosis of hepatocellular carcinoma cells.
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Affiliation(s)
- Yi-Lin Chen
- Graduate Institute of Biotechnology and Department of Applied Animal Science, National Ilan University, Ilan, Taiwan, Republic of China
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198
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Ki SH, Kim SG. Phase II enzyme induction by α-lipoic acid through phosphatidylinositol 3-kinase-dependent C/EBPs activation. Xenobiotica 2008; 38:587-604. [DOI: 10.1080/00498250802126920] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- S. H. Ki
- Innovative Drug Research Center for Metabolic and Inflammatory Disease, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul, Korea
| | - S. G. Kim
- Innovative Drug Research Center for Metabolic and Inflammatory Disease, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University , Seoul, Korea
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199
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Lee CW, Kim NH, Choi HK, Sun Y, Nam JS, Rhee HJ, Chun J, Huh SO. Lysophosphatidic acid-induced c-fos up-regulation involves cyclic AMP response element-binding protein activated by mitogen- and stress-activated protein kinase-1. J Cell Biochem 2008; 104:785-94. [PMID: 18172855 DOI: 10.1002/jcb.21663] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Lysophosphatidic acid (LPA) is a lipid growth factor that exerts diverse biological effects through its cognate receptor-mediated signaling cascades. Recently, we reported that LPA stimulates cAMP response element-binding protein (CREB) through mitogen- and stress-activated protein kinase-1 (MSK1). Previously, LPA has been shown to stimulate c-fos mRNA expression in Rat-2 fibroblast cells via a serum response element binding protein (SRF). However, involvement of CREB in LPA-stimulated c-fos gene expression is not elucidated yet. To investigate the CREB-mediated c-fos activation by LPA, various c-fos promoter-reporter constructs containing wild-type and mutated SRE and CRE were tested for their inducibility by LPA in transient transfection assays. LPA-stimulated c-fos promoter activation was markedly decreased when SRE and CRE were mutated. A dominant negative CREB significantly down-regulated the LPA-stimulated c-fos promoter activation. Chromatin immunoprecipitation assay revealed that LPA induced an increased binding of phosphorylated CREB and CREB-binding protein (CBP) to the CRE region of the endogenous c-fos promoter. Immunoblot analyses with various pharmacological inhibitors further showed that LPA induces up-regulation of c-fos mRNA level by activation of ERK, p38 MAPK, and MSK1. Taken together, our results suggest that CREB plays an important role in up-regulation of c-fos mRNA level in LPA-stimulated Rat-2 fibroblast cells.
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Affiliation(s)
- Chang-Wook Lee
- Department of Molecular Biology, Helen L. Dorris Child and Adolescent Neuropsychiatric Disorder Institute, The Scripps Research Institute, La Jolla, California 92037, USA
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200
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Siu YT, Ching YP, Jin DY. Activation of TORC1 transcriptional coactivator through MEKK1-induced phosphorylation. Mol Biol Cell 2008; 19:4750-61. [PMID: 18784253 DOI: 10.1091/mbc.e08-04-0369] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
CREB is a prototypic bZIP transcription factor and a master regulator of glucose metabolism, synaptic plasticity, cell growth, apoptosis, and tumorigenesis. Transducers of regulated CREB activity (TORCs) are essential transcriptional coactivators of CREB and an important point of regulation on which various signals converge. In this study, we report on the activation of TORC1 through MEKK1-mediated phosphorylation. MEKK1 potently activated TORC1, and this activation was independent of downstream effectors MEK1/MEK2, ERK2, JNK, p38, protein kinase A, and calcineurin. MEKK1 induced phosphorylation of TORC1 both in vivo and in vitro. Expression of the catalytic domain of MEKK1 alone in cultured mammalian cells sufficiently caused phosphorylation and subsequent activation of TORC1. MEKK1 physically interacted with TORC1 and stimulated its nuclear translocation. An activation domain responsive to MEKK1 stimulation was mapped to amino acids 431-650 of TORC1. As a physiological activator of CREB, interleukin 1alpha triggered MEKK1-dependent phosphorylation of TORC1 and its consequent recruitment to the cAMP response elements in the interleukin 8 promoter. Taken together, our findings suggest a new mechanism for regulated activation of TORC1 transcriptional coactivator and CREB signaling.
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Affiliation(s)
- Yeung-Tung Siu
- Department of Biochemistry and Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong
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