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Grass Carp Prolactin Gene: Structural Characterization and Signal Transduction for PACAP-induced Prolactin Promoter Activity. Sci Rep 2018; 8:4655. [PMID: 29545542 PMCID: PMC5854708 DOI: 10.1038/s41598-018-23092-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 03/05/2018] [Indexed: 01/09/2023] Open
Abstract
In this study, structural analysis of grass carp prolactin (PRL) gene was performed and the signaling mechanisms for pituitary adenylate cyclase-activating peptide (PACAP) regulation of PRL promoter activity were investigated. In αT3-1 cells, PRL promoter activity could be induced by oPACAP38 which was blocked by PACAP antagonist but not the VIP antagonist. The stimulatory effect of oPACAP38 was mimicked by activation of AC/cAMP and voltage-sensitive Ca2+ channel (VSCC) signaling, or induction of Ca2+ entry. In parallel, PACAP-induced PRL promoter activity was negated or inhibited by suppressing cAMP production, inhibiting PKA activity, removal of extracellular Ca2+, VSCC blockade, calmodulin (CaM) antagonism, and inactivation of CaM kinase II. Similar sensitivity to L-type VSCC, CaM and CaM kinase II inhibition were also observed by substituting cAMP analog for oPACAP38 as the stimulant for PRL promoter activity. Moreover, PACAP-induced PRL promoter activity was also blocked by inhibition of PLC signaling, attenuation of [Ca2+]i immobilization via IP3 receptors, and blockade of PI3K/P70S6K pathway. The PACAP-induced PRL promoter activation may involve transactivation of the transcription factor CREB. These results suggest that PACAP can stimulate PRL promoter activation by PAC1 mediated functional coupling of the Ca2+/CaM/CaM kinase II cascades with the AC/cAMP/PKA pathway. Apparently, other signaling pathways, including PLC/IP3 and PI3K/P70S6K cascades, may also be involved in PACAP induction of PRL gene transcription.
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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: 0.9] [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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Yu Z, Li M, Zhang D, Xu W, Kone BC. Sp1 trans-activates the murine H(+)-K(+)-ATPase alpha(2)-subunit gene. Am J Physiol Renal Physiol 2009; 297:F63-70. [PMID: 19420113 DOI: 10.1152/ajprenal.00039.2009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The H(+)-K(+)-ATPase alpha(2) (HKalpha2) gene of the renal collecting duct and distal colon plays a central role in potassium and acid-base homeostasis, yet its transcriptional control remains poorly characterized. We previously demonstrated that the proximal 177 bp of its 5'-flanking region confers basal transcriptional activity in murine inner medullary collecting duct (mIMCD3) cells and that NF-kappaB and CREB-1 bind this region to alter transcription. In the present study, we sought to determine whether the -144/-135 Sp element influences basal HKalpha2 gene transcription in these cells. Electrophoretic mobility shift and supershift assays using probes for -154/-127 revealed Sp1-containing DNA-protein complexes in nuclear extracts of mIMCD3 cells. Chromatin immunoprecipitation (ChIP) assays demonstrated that Sp1, but not Sp3, binds to this promoter region of the HKalpha2 gene in mIMCD3 cells in vivo. HKalpha2 minimal promoter-luciferase constructs with point mutations in the -144/-135 Sp element exhibited much lower activity than the wild-type promoter in transient transfection assays. Overexpression of Sp1, but not Sp3, trans-activated an HKalpha2 proximal promoter-luciferase construct in mIMCD3 cells as well as in SL2 insect cells, which lack Sp factors. Conversely, small interfering RNA knockdown of Sp1 inhibited endogenous HKalpha2 mRNA expression, and binding of Sp1 to chromatin associated with the proximal HKalpha2 promoter without altering the binding or regulatory influence of NF-kappaB p65 or CREB-1 on the proximal HKalpha2 promoter. We conclude that Sp1 plays an important and positive role in controlling basal HKalpha2 gene expression in mIMCD3 cells in vivo and in vitro.
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Affiliation(s)
- Zhiyuan Yu
- Departments of Medicine and of Biochemistry and Molecular Biology, University of Florida College of Medicine, Gainesville, Florida 32610, USA
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Xie Z, Geiger TR, Johnson EN, Nyborg JK, Druey KM. RGS13 acts as a nuclear repressor of CREB. Mol Cell 2008; 31:660-70. [PMID: 18775326 DOI: 10.1016/j.molcel.2008.06.024] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 05/01/2008] [Accepted: 06/18/2008] [Indexed: 01/22/2023]
Abstract
Cyclic AMP-induced phosphorylation of the transcription factor CREB elicits expression of genes mediating diverse biological functions. In lymphoid organs, the neurotransmitter norepinephrine stimulates beta(2)-adrenergic receptors on B lymphocytes to promote CREB-dependent expression of genes like the B cell Oct 2 coactivator (OCA-B). Although CREB phosphorylation recruits cofactors such as CBP/p300 to stimulate transcription, bona fide endogenous inhibitors of CREB-coactivator or CREB-DNA interactions have not emerged. Here, we identified RGS13, a member of the Regulator of G protein Signaling (RGS) protein family, as a nuclear factor that suppresses CREB-mediated gene expression. cAMP or Ca(2+) signaling promoted RGS13 accumulation in the nucleus, where it formed a complex with phosphorylated CREB and CBP/p300. RGS13 reduced the apparent affinity of pCREB for both the CRE and CBP. B lymphocytes from Rgs13(-/-) mice had more beta(2)-agonist-induced OCA-B expression. Thus, RGS13 inhibits CREB-dependent transcription of target genes through disruption of complexes formed at the promoter.
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Affiliation(s)
- Zhihui Xie
- Molecular Signal Transduction Section, Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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Mutiara S, Kanasaki H, Harada T, Miyazaki K. Dopamine D(2) receptor expression and regulation of gonadotropin alpha-subunit gene in clonal gonadotroph LbetaT2 cells. Mol Cell Endocrinol 2006; 259:22-9. [PMID: 16959402 DOI: 10.1016/j.mce.2006.07.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Revised: 07/21/2006] [Accepted: 07/26/2006] [Indexed: 11/28/2022]
Abstract
This study investigated the role of dopamine on the regulation of gonadotropin secretion at the gonadotroph cell line. We examined the function of the dopamine D(2) receptor in the regulation of pituitary gonadotropin gene expression using LbetaT2 cells, a mature, well differentiated clonal gonadotroph cell line. The presence of the dopamine D(2) receptor in the LbetaT2 cells was confirmed by both RT-PCR and Western blot. Gonadotropin releasing hormone (GnRH) stimulation resulted in gonadotropin LHbeta, FSHbeta and alpha-subunit promoter activation, and none were inhibited by quinpirol, a specific dopamine D(2) receptor agonist. Pituitary adenylate cyclase-activating polypeptide (PACAP) increased gonadotropin alpha-subunit promoter activity, but not LHbeta and FSHbeta promoter activity. The activity of PACAP was significantly inhibited in the presence of quinpirol. The protein kinase A inhibitor, H89, also inhibited PACAP-induced alpha-subunit gene expression. PACAP increased intracellular cAMP more than GnRH did in LbetaT2 cells, and the elevation of cAMP was strongly inhibited in the presence of various dopamine D(2) agonists. These results suggest that in pituitary gonadotrophs, the dopamine D(2) receptor is a negative regulator of gonadotropin alpha-subunit gene expression which is induced by cAMP-elevating factors in a cAMP-dependent pathway.
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Affiliation(s)
- Sandra Mutiara
- Department of Obstetrics and Gynecology, Shimane University, School of Medicine, Enya Cho 89-1, Izumo 693-8501, Shimane Prefecture, Japan
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Yoshida T, Mishina M. Distinct roles of calcineurin-nuclear factor of activated T-cells and protein kinase A-cAMP response element-binding protein signaling in presynaptic differentiation. J Neurosci 2006; 25:3067-79. [PMID: 15788763 PMCID: PMC6725083 DOI: 10.1523/jneurosci.3738-04.2005] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Synaptic vesicle accumulation and morphological changes are characteristic features of axon terminal differentiation during synaptogenesis. To investigate the regulatory mechanism that orchestrates synaptic molecules to form mature presynaptic terminals, we visualized a single axon terminal of zebrafish olfactory sensory neurons in vivo and examined the effects of the neuron-specific gene manipulations on the axon terminal differentiation. Synaptic vesicles visualized with vesicle-associated membrane protein 2 (VAMP2)-enhanced green fluorescent protein (EGFP) fusion protein gradually accumulated in axon terminals, whereas the axon terminals visualized with GAP43 fused with EGFP remodeled from complex shapes with filopodia to simple shapes without filopodia from 50 h postfertilization (hpf) to 84 hpf. Expression of dominant-negative protein kinase A (PKA) or cAMP response element-binding protein (CREB) suppressed the VAMP2-EGFP punctum formation in axon terminals during synaptogenesis. Consistently, constitutively active PKA or CREB stimulated VAMP2-EGFP puncta formation. On the other hand, cyclosporine A treatment or suppression of nuclear factor of activated T cells (NFAT) activation prevented the axon terminal remodeling from complex to simple shapes during synaptogenesis. Consistently, expression of constitutively active calcineurin accelerated the axon terminal remodeling. These results suggest that calcineurin-NFAT signaling regulates axon terminal remodeling, and PKA-CREB signaling controls synaptic vesicle accumulation.
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Affiliation(s)
- Tomoyuki Yoshida
- Department of Molecular Neurobiology and Pharmacology, Graduate School of Medicine, University of Tokyo, and Solution-Oriented Research for Science and Technology, Japan Science and Technology Corporation, Tokyo 113-0033, Japan
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Sarkar DK, Chaturvedi K, Oomizu S, Boyadjieva NI, Chen CP. Dopamine, dopamine D2 receptor short isoform, transforming growth factor (TGF)-beta1, and TGF-beta type II receptor interact to inhibit the growth of pituitary lactotropes. Endocrinology 2005; 146:4179-88. [PMID: 15961557 PMCID: PMC2872191 DOI: 10.1210/en.2005-0430] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The neurotransmitter dopamine is known to inhibit prolactin secretion and the proliferation of lactotropes in the pituitary gland. In this study, we determined whether dopamine and TGFbeta1 interact to regulate lactotropic cell proliferation. We found that dopamine and the dopamine agonist bromocriptine stimulated TGFbeta1 secretion and TGFbeta1 mRNA expression but inhibited lactotropic cell proliferation both in vivo and in vitro. The dopamine's inhibitory action on lactotropic cell proliferation was blocked by a TGFbeta1-neutralizing antibody. We also found that PR1 cells, which express low amounts of the dopamine D2 receptor, demonstrated reduced expression of TGFbeta1 type II receptor and TGFbeta1 mRNA levels and had undetectable levels of TGFbeta1 protein. These cells showed a reduced TGFbeta1 growth-inhibitory response. Constitutive expression of the D2 receptor short isoform, but not the D2 receptor long isoform, induced TGFbeta1 and TGFbeta1 type II receptor gene expression and recovered dopamine- and TGFbeta1-induced growth inhibition in PR1 cells. The constitutive expression of D2 receptor short isoform also reduced the tumor cell growth rate. These data suggest that a TGFbeta1 system may mediate, in part, the growth-inhibitory action of dopamine on lactotropes.
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MESH Headings
- Activin Receptors, Type I/genetics
- Activin Receptors, Type I/physiology
- Animals
- Bromocriptine/pharmacology
- Cells, Cultured
- Dopamine/pharmacology
- Estradiol/pharmacology
- Female
- Hypothalamic Hormones/metabolism
- Ovariectomy
- Pituitary Gland, Anterior/cytology
- Pituitary Gland, Anterior/drug effects
- Pituitary Gland, Anterior/physiology
- Protein Serine-Threonine Kinases
- RNA, Messenger/genetics
- Rats
- Rats, Inbred F344
- Receptor, Transforming Growth Factor-beta Type I
- Receptor, Transforming Growth Factor-beta Type II
- Receptors, Dopamine D2/physiology
- Receptors, Transforming Growth Factor beta/genetics
- Receptors, Transforming Growth Factor beta/physiology
- Transforming Growth Factor beta/genetics
- Transforming Growth Factor beta/metabolism
- Transforming Growth Factor beta/physiology
- Transforming Growth Factor beta1
- Transforming Growth Factor beta2
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Affiliation(s)
- D K Sarkar
- Endocrinology Program, Biomedical Division of the Center of Alcohol Studies and Department of Animal Sciences, Rutgers, The State University of New Jersey, New Brunswick 08901, USA.
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Najwer I, Lilly B. Ca2+/calmodulin-dependent protein kinase IV activates cysteine-rich protein 1 through adjacent CRE and CArG elements. Am J Physiol Cell Physiol 2005; 289:C785-93. [PMID: 15917302 DOI: 10.1152/ajpcell.00098.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Smooth muscle-specific transcription is controlled by a multitude of transcriptional regulators that cooperate to drive expression in a temporospatial manner. Previous analysis of the cysteine-rich protein 1 ( CRP1/Csrp) gene revealed an intronic enhancer that is sufficient for expression in arterial smooth muscle cells and requires a serum response factor-binding CArG element for activity. The presence of a CArG box in smooth muscle regulatory regions is practically invariant; however, it stands to reason that additional elements contribute to the modulation of transcription in concert with the CArG. Because of the potential importance of other regulatory elements for expression of the CRP1 gene, we sought to identify additional motifs within the enhancer that are necessary for expression. In this effort, we identified a conserved cAMP response element (CRE) that, when mutated, diminishes the expression of the enhancer in cultured vascular smooth muscle cells. Using transfection and electrophoretic mobility shift assays, we have shown that the CRE binds the cAMP response element-binding protein (CREB) and is activated by Ca2+/calmodulin-dependent protein kinase IV (CaMKIV), but not by CaMKII. Furthermore, our data demonstrate that CaMKIV stimulates CRP1 expression not only through the CRE but also through the CArG box. These findings represent evidence of a functional CRE within a smooth muscle-specific gene and provide support for a mechanism in which CREB functions as a smooth muscle determinant through CaMKIV activation.
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Affiliation(s)
- Ida Najwer
- Vascular Biology Center and Department of Obstetrics and Gynecology, Medical College of Georgia, 1459 Laney Walker Blvd., CB3207, Augusta, Georgia 30912-2500, USA
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Xu X, Zhang W, Kone BC. CREB trans-activates the murine H(+)-K(+)-ATPase alpha(2)-subunit gene. Am J Physiol Cell Physiol 2004; 287:C903-11. [PMID: 15163620 DOI: 10.1152/ajpcell.00065.2004] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite its key role in potassium homeostasis, transcriptional control of the H(+)-K(+)-ATPase alpha(2)-subunit (HKalpha(2)) gene in the collecting duct remains poorly characterized. cAMP increases H(+)-K(+)-ATPase activity in the collecting duct, but its role in activating HKalpha(2) transcription has not been explored. Previously, we demonstrated that the proximal 177 bp of the HKalpha(2) promoter confers basal collecting duct-selective expression. This region contains several potential cAMP/Ca(2+)-responsive elements (CRE). Accordingly, we examined the participation of CRE-binding protein (CREB) in HKalpha(2) transcriptional control in murine inner medullary collecting duct (mIMCD)-3 cells. Forskolin and vasopressin induced HKalpha(2) mRNA levels, and CREB overexpression stimulated the activity of HKalpha(2) promoter-luciferase constructs. Serial deletion analysis revealed that CREB inducibility was retained in a construct containing the proximal 100 bp of the HKalpha(2) promoter. In contrast, expression of a dominant negative inhibitor (A-CREB) resulted in 60% lower HKalpha(2) promoter-luciferase activity, suggesting that constitutive CREB participates in basal HKalpha(2) transcriptional activity. A constitutively active CREB mutant (CREB-VP16) strongly induced HKalpha(2) promoter-luciferase activity, whereas overexpression of CREBdLZ-VP16, which lacks the CREB DNA-binding domain, abolished this activation. In vitro DNase I footprinting and gel shift/supershift analysis of the proximal promoter with recombinant glutathione S-transferase (GST)-CREB-1 and mIMCD-3 cell nuclear extracts revealed sequence-specific DNA-CREB-1 complexes at -86/-60. Mutation at three CRE-like sequences within this region abolished CREB-1 DNA-binding activity and abrogated CREB-VP16 trans-activation of the HKalpha(2) promoter. In contrast, mutation of the neighboring -104/-94 kappabeta element did not alter CREB-VP16 trans-activation of the HKalpha(2) promoter. Thus CREB-1, binding to one or more CRE-like elements in the -86/-60 region, trans-activates the HKalpha(2) gene and may represent an important link between rapid and delayed effects of cAMP on HKalpha(2) activity.
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Affiliation(s)
- Xiangyang Xu
- Department of Internal Medicine, University of Texas Medical School at Houston, 6431 Fannin Ave., MSB 1.150, Houston, TX 77030, USA
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Mbebi C, Sée V, Mercken L, Pradier L, Müller U, Loeffler JP. Amyloid precursor protein family-induced neuronal death is mediated by impairment of the neuroprotective calcium/calmodulin protein kinase IV-dependent signaling pathway. J Biol Chem 2002; 277:20979-90. [PMID: 11877414 DOI: 10.1074/jbc.m107948200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aberrant metabolism of beta-amyloid precursor protein (APP) and the progressive deposition of its derived fragment beta-amyloid peptide are early and constant pathological hallmarks of Alzheimer's disease. Because APP is able to function as a cell surface receptor, we investigated here whether a disruption of the normal function of APP may contribute to the pathogenic mechanisms in Alzheimer's disease. To this aim, we generated a specific chicken polyclonal antibody directed against the extracellular domain of APP, which is common with the beta-amyloid precursor-like protein type 2. Exposure of cultured cortical neurons to this antibody (APP-Ab) induced cell death preceded by neurite degeneration, oxidative stress, and nuclear condensation. Interestingly, caspase-3-like protease was not activated in this neurotoxic action suggesting a different mode of cell death than classical apoptosis. Further analysis of the molecular mechanisms revealed a calpain- and calcineurin-dependent proteolysis of the neuroprotective calcium/calmodulin-dependent protein kinase IV and its nuclear target protein cAMP responsive element binding protein. These effects were abolished by the G protein inhibitor pertussis toxin, strongly suggesting that APP binding operates via a GTPase-dependent pathway to cause neuronal death.
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Affiliation(s)
- Corinne Mbebi
- Université Louis Pasteur, Faculté de Médecine, EA 3433 Molecular signaling and neurodegeneration, 67000 Strasbourg, France
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Sée V, Loeffler JP. Oxidative stress induces neuronal death by recruiting a protease and phosphatase-gated mechanism. J Biol Chem 2001; 276:35049-59. [PMID: 11443132 DOI: 10.1074/jbc.m104988200] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Reactive oxygen species (ROS) cause death of cerebellar granule neurons. Here, a 15-min pulse of H(2)O(2) (100 microm) induced an active process of neuronal death distinct from apoptosis. Oxidative stress activated a caspase-independent but calpain-dependent decline of calcium/calmodulin-dependent protein kinase IV and cAMP- responsive element-binding protein (CREB). Calpain inhibitors restored calcium/calmodulin-dependent protein kinase IV and CREB but did not influence phosphorylated CREB levels or survival, indicating recruitment of an additional dephosphorylation process. Co-treatment with calpain and serine/threonine phosphatase inhibitors restored pCREB levels and rescued neurons. This phosphatase-activated signaling pathway was shown to be dependent on de novo protein synthesis. Further, gene transfer studies revealed that CREB is a common final effector of both apoptosis and ROS-induced death. Our data indicate that dephosphorylation and proteolytic signaling mechanisms underlie ROS-induced programmed cell death.
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Affiliation(s)
- V Sée
- Université Louis Pasteur, Faculty of Medicine, E. A. Molecular Signaling and Neurodegeneration, 11 rue Humann, Strasbourg 67000, France
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Fliss MS, Hinkle PM, Bancroft C. Expression cloning and characterization of PREB (prolactin regulatory element binding), a novel WD motif DNA-binding protein with a capacity to regulate prolactin promoter activity. Mol Endocrinol 1999; 13:644-57. [PMID: 10194769 DOI: 10.1210/mend.13.4.0260] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Previous studies have implied that a transcription factor(s) other than Pit-1 is involved in homeostatic regulation of PRL promoter activity via Pit-1-binding elements. One such element, 1P, was employed to clone from a rat pituitary cDNA expression library a novel 417-amino acid WD protein, designated PREB (PRL regulatory element binding) protein. PREB contains two PQ-rich potential transactivation domains, but no apparent DNA-binding motif, and exhibits sequence-specific binding to site 1P, to a site nonidentical to that for Pit-1. The PREB gene (or a related gene) is conserved, as an apparently single copy, in rat, human, fly, and yeast. A single approximately 1.9-kb PREB transcript accumulates in GH3 rat pituitary cells, to levels similar to Pit-1 mRNA. PREB transcripts were detected in all human tissues examined, but the observation of tissue-specific multiple transcript patterns suggests the possibility of tissue-specific alternative splicing. RT-PCR analysis of human brain tumor RNA samples suggested region-specific expression of PREB transcripts in brain. Western and immunocytochemical analysis implied that PREB accumulates specifically in GH3 cell nuclei. Transient transfection employing PREB-negative C6 rat glial cells showed that PREB is as active as, and additive with, Pit-1 in transactivation of a PRL promoter construct, and that PREB, but not Pit-1, can mediate transcriptional activation by protein kinase A (PKA). Expression in GH3 cells of a GAL4-PREB fusion protein both strongly transactivated a 5XGAL indicator construct and yielded a further stimulation of expression of this construct by coexpressed PKA, implying that PREB can mediate both basal and PKA-stimulated transcriptional responses in pituitary cells. These observations imply that PREB will prove to play a significant transcriptional regulatory role, both in the pituitary and in other organs in which transcripts of its gene are expressed.
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Affiliation(s)
- M S Fliss
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, New York 10029, USA
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Subramaniam N, Cairns W, Okret S. Glucocorticoids repress transcription from a negative glucocorticoid response element recognized by two homeodomain-containing proteins, Pbx and Oct-1. J Biol Chem 1998; 273:23567-74. [PMID: 9722596 DOI: 10.1074/jbc.273.36.23567] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Several studies have established that the prolactin (PRL) gene is expressed not only in lactotrophs and somatotrophs of the anterior pituitary but, albeit to a lesser extent, in non-pituitary cells like human thymocytes, decidualized endometrium, mammary glands during lactation, and some human non-pituitary cell lines. Despite the requirement in the pituitary for the pituitary-specific transcription factor Pit-1/GHF-1 for PRL expression, the expression in non-pituitary cells occurs in the absence of Pit-1/GHF-1 and can be repressed by glucocorticoids. This prompted us to investigate the transcription factors in non-pituitary cells which are involved in controlling expression and glucocorticoid repression of a previously characterized negative glucocorticoid response element from the bovine prolactin gene (PRL3 nGRE). Here we have demonstrated that non-pituitary cells (COS-7 and mouse hepatoma Hepa1c1c7 cells) conferred increased expression via the PRL3 nGRE mainly because of the binding of the ubiquitously expressed POU-homeodomain-containing octamer transcription factor-1 (Oct-1) to an AT-rich sequence present in the PRL3 sequence. However, full transcriptional activity required the binding of a second ubiquitously expressed homeodomain-containing protein, Pbx, previously shown to bind cooperatively with several homeotic selector proteins. The Pbx binding site in the PRL3 nGRE, located just upstream of the Oct-1 binding site, showed a strong sequence similarity with known Pbx binding sites and bound Pbx with an affinity similar to that of other established Pbx target sequences. Interestingly, both Oct-1 and Pbx binding to the PRL3 nGRE were found to be required for glucocorticoid repression. Addition of in vitro translated glucocorticoid receptor DNA binding domain to the nuclear extract prevented Oct-1 and Pbx from binding to the PRL element. The involvement of the homeobox protein Pbx in glucocorticoid repression via an nGRE identifies a new role for this protein.
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Affiliation(s)
- N Subramaniam
- Department of Medical Nutrition, Karolinska Institute, Huddinge University Hospital, F60 Novum, S-141 86 Huddinge, Sweden
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