Pulses of Prolactin Promoter Activity Depend on a Noncanonical E-Box that Can Bind the Circadian Proteins CLOCK and BMAL1

Abstract Recent findings from our laboratory and those of others demonstrated that prolactin gene expression (PRL-GE) oscillates in single living mammotropes, but little information is available on the molecular processes that contribute to this phenomenon. To elucidate the source of this activity, we generated a series of constructs containing decreasing lengths of the PRL promoter fused to a luciferase reporter gene. These constructs were injected into single cells and assayed for photonic activity. We found pulse activity with all plasmids tested, even with the smallest promoter fragment of 331 bp. Sequence analysis of this fragment identified two potential E-boxes (elements known to bind CLOCK and BMAL1 circadian proteins). Furthermore, RT-PCR of PRL cells (pituitary, MMQ, and GH3) revealed expression of clock and bmal1 as well as five other clock genes (per1, per2, cry1, cry2, and tim), suggesting that the circadian system may function in PRL cells. Next, we mutated the core sequences of both E-boxes within the 2.5-kb PRL promoter and found that only mutation of the E-box133 completely abolished PRL-GE pulses. EMSAs revealed that CLOCK and BMAL1 were able to bind to the E-box133 site in vitro. Our results demonstrate that PRL-GE pulses are dependent on a specific E-box binding site in the PRL promoter. Moreover, the indication that CLOCK/BMAL1 can bind to this site suggests that these circadian proteins, either alone or in conjunction with other factors, may regulate intermittent PRL promoter activity in mammotropes, perhaps by acting as a temporal switch for the on/off expression of PRL.

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Calcium Dynamics and Resting Transcriptional Activity Regulates Prolactin Gene Expression

Endocrinology ◽

10.1210/en.2002-220266 ◽

2002 ◽

Vol 143 (9) ◽

pp. 3548-3554 ◽

Cited By ~ 8

Author(s):

Carlos Villalobos ◽

Lucía Núñez ◽

William J. Faught ◽

David C. Leaumont ◽

Fredric R. Boockfor ◽

...

Keyword(s):

Gene Expression ◽

Promoter Activity ◽

Gene Promoter ◽

Luciferase Reporter ◽

Pituitary Cells ◽

Luciferase Reporter Gene ◽

Transcriptional Responses ◽

Prolactin Gene ◽

Before And After ◽

Single Living

Abstract Research on the regulation of hormone gene expression by calcium signaling is hampered by the difficulty of monitoring both parameters within the same individual, living cells. Here we achieved concurrent, dynamic measurements of both intracellular Ca2+ concentration ([Ca2+]i) and prolactin (PRL) gene promoter activity in single, living pituitary cells. Cells were transfected with the luciferase reporter gene under control of the PRL promoter and subjected to bioluminescence and fluorescence imaging before and after presentation of TSH-releasing hormone (TRH), a prototypic regulator of PRL secretion and gene expression that induces a transient Ca2+ release, followed by sustained Ca2+ influx. We found that cells displaying specific photonic emissions (i.e. mammotropes) showed heterogeneous calcium and transcriptional responses to TRH. Transcriptionally responsive cells always exhibited a TRH-induced [Ca2+]i increase. In addition, transcriptional responses were related to the rate of Ca2+ entry but not Ca2+ release. Finally, cells lacking transcriptional responses (but showing [Ca2+]i rises) exhibited larger levels of resting PRL promoter activity than transcriptionally responsive cells. Thus, our results suggest that the sustained entry of Ca2+ induced by TRH (but not the Ca2+ release) regulates transcriptional responsiveness. Superimposed on this regulation, the previous, resting PRL promoter activity also controls transcriptional responses.

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DEC1 Modulates the Circadian Phase of Clock Gene Expression

Molecular and Cellular Biology ◽

10.1128/mcb.02168-07 ◽

2008 ◽

Vol 28 (12) ◽

pp. 4080-4092 ◽

Cited By ~ 92

Author(s):

Ayumu Nakashima ◽

Takeshi Kawamoto ◽

Kiyomasa K. Honda ◽

Taichi Ueshima ◽

Mitsuhide Noshiro ◽

...

Keyword(s):

Gene Expression ◽

Clock Genes ◽

Luciferase Reporter ◽

Constant Darkness ◽

Mobility Shift ◽

Behavioral Rhythms ◽

Circadian Phase ◽

Clock Gene Expression ◽

E Box ◽

E Boxes

ABSTRACT DEC1 suppresses CLOCK/BMAL1-enhanced promoter activity, but its role in the circadian system of mammals remains unclear. Here we examined the effect of Dec1 overexpression or deficiency on circadian gene expression triggered with 50% serum. Overexpression of Dec1 delayed the phase of clock genes such as Dec1, Dec2, Per1, and Dbp that contain E boxes in their regulatory regions, whereas it had little effect on the circadian phase of Per2 and Cry1 carrying CACGTT E′ boxes. In contrast, Dec1 deficiency advanced the phase of the E-box-containing clock genes but not that of the E′-box-containing clock genes. Accordingly, DEC1 showed strong binding and transrepression on the E box, but not on the E′ box, in chromatin immunoprecipitation, electrophoretic mobility shift, and luciferase reporter assays. Dec1 −/− mice showed behavioral rhythms with slightly but significantly longer circadian periods under conditions of constant darkness and faster reentrainment to a 6-h phase-advanced shift of a light-dark cycle. Knockdown of Dec2 with small interfering RNA advanced the phase of Dec1 and Dbp expression, and double knockdown of Dec1 and Dec2 had much stronger effects on the expression of the E-box-containing clock genes. These findings suggest that DEC1, along with DEC2, plays a role in the finer regulation and robustness of the molecular clock.

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Peroxisome-Proliferator Receptor γ Represses Hepatic Sex Hormone-Binding Globulin Expression

Endocrinology ◽

10.1210/en.2008-1289 ◽

2009 ◽

Vol 150 (5) ◽

pp. 2183-2189 ◽

Cited By ~ 28

Author(s):

David M. Selva ◽

Geoffrey L. Hammond

Keyword(s):

Hepg2 Cells ◽

Promoter Activity ◽

Binding Activity ◽

Sex Hormone Binding Globulin ◽

Luciferase Reporter ◽

Peroxisome Proliferator ◽

Luciferase Reporter Gene ◽

Pparγ Agonist ◽

Gene Assay

Plasma SHBG production by the liver is influenced by its metabolic state, and hepatocyte nuclear factor-4α regulates SHBG expression in response to changes in lipogenesis. Peroxisome-proliferator receptors (PPARs) also regulate glucose homeostasis and fatty acid metabolism. The human SHBG promoter contains a PPAR-response element (PPAR-RE), and plasma SHBG levels increase in polycystic ovarian syndrome patients treated with the PPARγ agonist, rosiglitazone. In addition, plasma SHBG levels are associated with a genetic polymorphism in the PPARγ-2 coding sequence that alters its transcriptional activity. Therefore, we set out to determine whether PPARγ influences hepatic production of SHBG by using human HepG2 hepatoblastoma cells as an in vitro model. Surprisingly, treatment of HepG2 cells with rosiglitazone reduced SHBG production and SHBG promoter activity (as assessed in a luciferase reporter gene assay) by 20–25%, whereas the PPARγ antagonist, GW9662, increased both by 2- to 3-fold. The effects of PPARγ agonists and antagonists on SHBG promoter activity were substantially diminished when the PPAR-RE in the SHBG promoter was mutated. A PPARγ small interfering RNA also increased SHBG production by HepG2 cells as well as SHBG promoter activity, and the latter was accentuated by cotreatment with GW9662. Importantly, overexpression of a PPARγ-2 Pro12 variant in HepG2 cells was more effective at reducing SHBG promoter activity, when compared with PPARγ-2 Ala12, consistent with its superior PPAR-RE binding activity. We conclude that PPARγ represses human SHBG expression in liver cells, and that differences in PPARγ levels and activity contribute directly to variations in plasma SHBG levels.

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CD40/CD40 LIGAND INTERACTIONS AND TNFα TREATMENT REDUCE ACTIVITY OF P105 PROMOTER OF THE HUMAN PAPILLOMA VIRUS-18 IN VITRO

Experimental Oncology ◽

10.31768/2312-8852.2016.38(1):22-25 ◽

2016 ◽

Vol 38 (1) ◽

pp. 22-25 ◽

Cited By ~ 2

Author(s):

A Altenburg ◽

M B Abdel-Naser ◽

G Nikolakis ◽

T Wild ◽

N Wojtalewicz

Keyword(s):

Human Papilloma Virus ◽

Cervical Carcinoma ◽

Promoter Activity ◽

Cd40 Ligand ◽

Luciferase Reporter ◽

Luciferase Reporter Gene ◽

Papilloma Virus ◽

Gene Assay ◽

Ligand Interactions

Background: Cervical carcinoma cells including those infected with the oncogenic human papilloma virus (HPV) and several cervical carcinoma cell lines show a strong expression of the CD40 receptor, unlike benign cervical epithelial cells infected with HPV. The functional relevance of this up-regulated expression in the tumor is not fully understood. Nevertheless, it might offer a unique possibility to target those malignant cells due to the antiviral and antitumoral effects of the CD40/CD40 ligand (CD40L) interactions. Aim: In vitro assessment of the effect of CD40L on HPV 18-P105 promoter activity and the subsequent release of IL-6 by the promoter transfected HeLaCD40 cells, which express CD40 constitutively. Material and Methods: Transfection of HeLaCD40 cells was achieved by electroporation after optimizing the parameters by the pCMV-β-Gal vector and β-Gal stain. Transfected HeLaCD40 cells were challenged with BHKCD40L and TNFα, in addition to BHKwt and medium alone as controls. HPV18P105 promoter activity was demonstrated by luciferase reporter gene assay while IL-6 was assessed by ELISA. Results: CD40/ CD40L interactions and TNFα treatment significantly reduced HPV18-P105 promoter activity (56.0 ± 10.2% and 64.1 ± 9.1% vs. control, respectively; p < 0.001). Likewise, IL-6, which is a sensitive cytokine of CD40 activation, was significantly increased in HeLaCD40 cells in the same experiments (2.7 fold after stimulation with BHKCD40L and 5.2 fold after stimulation with TNFα vs. control; p < 0.01 and p < 0.001, respectively). Conclusion: It is likely that the CD40/CD40L interactions and TNFα are effective against cervical carcinomas by repressing transcriptional activity of HPV promoter. This can result in new adjuvant treatments.

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Ectopic Methylation of a Single Persistently Unmethylated CpG in the Promoter of the Vitellogenin Gene Abolishes Its Inducibility by Estrogen through Attenuation of Upstream Stimulating Factor Binding

Molecular and Cellular Biology ◽

10.1128/mcb.00436-19 ◽

2019 ◽

Vol 39 (23) ◽

Author(s):

Lia Kallenberger ◽

Rachel Erb ◽

Lucie Kralickova ◽

Andrea Patrignani ◽

Esther Stöckli ◽

...

Keyword(s):

Dna Methyltransferase ◽

Transcriptional Control ◽

Dna Demethylation ◽

Luciferase Reporter ◽

Luciferase Reporter Gene ◽

Reporter System ◽

E Box ◽

Stimulating Factor

ABSTRACT The enhancer/promoter of the vitellogenin II gene (VTG) has been extensively studied as a model system of vertebrate transcriptional control. While deletion mutagenesis and in vivo footprinting identified the transcription factor (TF) binding sites governing its tissue specificity, DNase hypersensitivity and DNA methylation studies revealed the epigenetic changes accompanying its hormone-dependent activation. Moreover, upon induction with estrogen (E2), the region flanking the estrogen-responsive element (ERE) was reported to undergo active DNA demethylation. We now show that although the VTG ERE is methylated in embryonic chicken liver and in LMH/2A hepatocytes, its induction by E2 was not accompanied by extensive demethylation. In contrast, E2 failed to activate a VTG enhancer/promoter-controlled luciferase reporter gene methylated by SssI. Surprisingly, this inducibility difference could be traced not to the ERE but rather to a single CpG in an E-box (CACGTG) sequence upstream of the VTG TATA box, which is unmethylated in vivo but methylated by SssI. We demonstrate that this E-box binds the upstream stimulating factor USF1/2. Selective methylation of the CpG within this binding site with an E-box-specific DNA methyltransferase, Eco72IM, was sufficient to attenuate USF1/2 binding in vitro and abolish the hormone-induced transcription of the VTG gene in the reporter system.

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Differential regulation of the TRH gene promoter by triiodothyronine and dexamethasone in pancreatic islets

Journal of Endocrinology ◽

10.1677/joe.0.1700091 ◽

2001 ◽

Vol 170 (1) ◽

pp. 91-98 ◽

Cited By ~ 4

Author(s):

P Fragner ◽

SL Lee ◽

S Aratan de Leon

Keyword(s):

Gene Expression ◽

Pancreatic Islets ◽

Promoter Activity ◽

Gene Promoter ◽

Luciferase Reporter ◽

Flanking Sequence ◽

Luciferase Reporter Gene ◽

Neoplastic Cells

TRH was initially found in the hypothalamus and regulates TSH secretion. TRH is also produced by insulin-containing beta-cells. Endogenous TRH positively regulates glucagon secretion and attenuates pancreatic exocrine secretion. We have previously shown that triiodothyronine (T(3)) down-regulates pre-pro-TRH gene expression in vivo and in vitro. The present study was designed to determine the initial impact of T(3) on rat TRH gene promoter and to compare this effect with that of dexamethasone (Dex). Primary islet cells and neoplastic cells (HIT T-15 and RIN m5F) were transiently transfected with fragments of the 5'-flanking sequence of TRH fused to the luciferase reporter gene. The persistence of high TRH concentrations in fetal islets in culture, probably due to transactivating factors, allowed us to explore how T(3) and Dex regulate the TRH promoter activity in transfected cells and whether the hormone effect is dependent on the cell type considered. TRH gene promoter activity is inhibited by T(3) in primary but not neoplastic cells and stimulated by Dex in both primary and neoplastic cells of islets. These findings validate previous in vivo and in vitro studies and indicate the transcriptional impact of these hormones on TRH gene expression in the pancreatic islets.

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Ectopic methylation of a single persistently-unmethylated CpG in the promoter of the vitellogenin gene abolishes its inducibility by estrogen through attenuation of USF binding

10.1101/768697 ◽

2019 ◽

Author(s):

Lia Kallenberger ◽

Rachel Erb ◽

Lucie Kralickova ◽

Andrea Patrignani ◽

Esther Stöckli ◽

...

Keyword(s):

Transcriptional Control ◽

Dna Demethylation ◽

Luciferase Reporter ◽

Luciferase Reporter Gene ◽

Reporter System ◽

Active Dna Demethylation ◽

E Box ◽

Vitellogenin Gene

ABSTRACTThe enhancer/promoter of the vitellogenin II (VTG) gene has been extensively studied as a model system of vertebrate transcriptional control. While deletion mutagenesis and in vivo footprinting identified the transcription factor (TF) binding sites governing its tissue specificity, DNase hypersensitivity- and DNA methylation studies revealed the epigenetic changes accompanying its hormone-dependent activation. Moreover, upon induction with estrogen (E2), the region flanking the estrogen-responsive element (ERE) was reported to undergo active DNA demethylation. We now show that although the VTG ERE is methylated in embryonic chicken liver and in LMH/2A hepatocytes, its induction by E2 was not accompanied by extensive demethylation. In contrast, E2 failed to activate a VTG enhancer/promoter-controlled luciferase reporter gene methylated by SssI. Surprisingly, this inducibility difference could be traced not to the ERE, but rather to a single CpG in an E-box (CACGTG) sequence upstream of the VTG TATA box, which is unmethylated in vivo, but methylated by SssI. We demonstrate that this E-box binds the upstream stimulating factor USF1/2. Selective methylation of the CpG within this binding site with an E-box-specific DNA methyltranferase Eco72IM was sufficient to attenuate USF1/2 binding in vitro and abolish the hormone-induced transcription of the VTG gene in the reporter system.

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Unusual 5'-regulatory structure and regulation of the murine Mlc1 gene: Lack of promoter-specific functional elements

Journal of Nucleic Acids Investigation ◽

10.4081/jnai.2011.2314 ◽

2011 ◽

Vol 2 (1) ◽

pp. 11

Author(s):

Darja Henseler ◽

Jonathan D. Turner ◽

Matthias Eckhardt ◽

Maaike Van der Mark ◽

Yanina Revsin ◽

...

Keyword(s):

Reporter Gene ◽

In Silico ◽

Promoter Activity ◽

Regulatory Elements ◽

Luciferase Reporter ◽

Regulatory Structure ◽

Luciferase Reporter Gene ◽

Promoter Regions ◽

Potential Promoter

The MLC1 gene is involved in an autosomal recessive neurological disorder, megalencephalic leucoencephalopathy with subcortical cysts (MLC), which is characterized by macrocephaly during the first year of life and swollen white matter (leucoencephaly). Variants of MLC1 have also been associated with psychiatric disorders such as schizophrenia, major depression and bipolar disorder. Currently, little is known about the encoded protein (MLC1). Judging from its similarity to other known proteins, it may serve as a trans-membrane transporter. However, the function of the encoded protein and its gene regulation has not been investigated successfully so far. We investigated the 5’ region of the murine Mlc1 with respect to regulatory elements for gene expression. A promoter search and an in silico analysis were conducted. Luciferase reporter gene constructs with potential promoter regions were created to study promoter activity in vitro. We found two alternative first exons for the murine Mlc1 but were not able to detect any promoter activity for the investigated reporter gene constructs in different cell lines, thus pointing to the presence of essential cis-acting elements far outside of the region. In silico analysis indicated an uncommon promoter structure for Mlc1, with CCAAT-boxes representing the only noticeable elements.

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Benzisothiazolone Derivatives Exhibit Cytotoxicity in Hodgkin’s Lymphoma Cells through NF-κB Inhibition and are Synergistic with Doxorubicin and Etoposide

Anti-Cancer Agents in Medicinal Chemistry ◽

10.2174/1871520620666200213103513 ◽

2020 ◽

Vol 20 (6) ◽

pp. 715-723

Author(s):

Natarajan Nandakumar ◽

Pushparathinam Gopinath ◽

Jacob Gopas ◽

Kannoth M. Muraleedharan

Keyword(s):

Synergistic Effect ◽

Hodgkin’S Lymphoma ◽

A549 Cells ◽

Hodgkin's Lymphoma ◽

Luciferase Reporter ◽

Luciferase Reporter Gene ◽

Lymphoma Cells ◽

Nuclear Extracts ◽

Gene Assay

Background: The authors investigated the NF-κB inhibitory role of three Benzisothiazolone (BIT) derivatives (1, 2 and 3) in Hodgkin’s Lymphoma cells (L428) which constitutively express activated NF-κB. All three compounds showed dose-dependent NF-κB inhibition (78.3, 70.7 and 34.6%) in the luciferase reporter gene assay and were found cytotoxic at IC50 values of 3.3μg/ml, 4.35μg/ml and 13.8μg/ml, respectively by the XTT assay. BIT 1and BIT 2 (but not BIT 3) suppressed both NF-κB subunits p50 and p65 in cytoplasmic and nuclear extracts in a concentration-dependent manner. Furthermore, BIT 1 showed a moderate synergistic effect with the standard chemotherapy drugs etoposide and doxorubicin, whereas BIT 2 and 3 showed a moderate additive effect to antagonistic effect. Cisplatin exhibited an antagonist effect on all the compounds tested under various concentrations, except in the case of 1.56μg/ml of BIT 3 with 0.156μg/ml of cisplatin. The compounds also inhibited the migration of adherent human lung adenocarcinoma cells (A549) in vitro. We conclude that especially BIT 1 and BIT 2 have in vitro anti-inflammatory and anti-cancer activities, which can be further investigated for future potential therapeutic use. Methods: Inspired by the electrophilic sulfur in Nuphar alkaloids, monomeric and dimeric benzisothiazolones were synthesized from dithiodibenzoic acid and their NF-κB inhibitory role was explored. NF-κB inhibition and cytotoxicity of the synthesized derivatives were studied using luciferase reporter gene assay and XTTassay. Immunocytochemistry studies were performed using L428 cells. Cell migration assay was conducted using the A549 cell line. L428 cells were used to conduct combination studies and the results were plotted using CompuSyn software. Results: Benzisothiazolone derivatives exhibited cytotoxicity in Hodgkin’s Lymphoma cells through NF-κB inhibition. Potent compounds showed suppression of both NF-κB subunits p50 and p65 in a concentrationdependent manner, both in cytoplasmic and nuclear extracts. Combination studies suggest that benzisothiazolone derivatives possess a synergistic effect with etoposide and doxorubicin. Furthermore, the compounds also inhibited the migration of A549 cells. Conclusion: Benzisothiazolones bearing one or two electrophilic sulfur atoms as part of the heterocyclic framework exhibited cytotoxicity in Hodgkin’s Lymphoma cells through NF-κB inhibition. In addition, these derivatives also exhibited a synergistic effect with etoposide and doxorubicin along with the ability to inhibit the migration of A549 cells. Our study suggests that BIT-based new chemical entities could lead to potential anticancer agents.

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Impact of RARα and miR-138 on retinoblastoma etoposide resistance

Tumor Biology ◽

10.3233/tub-200072 ◽

2021 ◽

Vol 43 (1) ◽

pp. 11-26

Author(s):

Maike Busch ◽

Natalia Miroschnikov ◽

Jaroslaw Thomas Dankert ◽

Marc Wiesehöfer ◽

Klaus Metz ◽

...

Keyword(s):

Cell Viability ◽

Cell Lines ◽

Cancer Progression ◽

Treated Patient ◽

Luciferase Reporter ◽

Luciferase Reporter Gene ◽

Gene Assay ◽

The Impact

BACKGROUND: Retinoblastoma (RB) is the most common childhood eye cancer. Chemotherapeutic drugs such as etoposide used in RB treatment often cause massive side effects and acquired drug resistances. Dysregulated genes and miRNAs have a large impact on cancer progression and development of chemotherapy resistances. OBJECTIVE: This study was designed to investigate the involvement of retinoic acid receptor alpha (RARα) in RB progression and chemoresistance as well as the impact of miR-138, a potential RARα regulating miRNA. METHODS: RARα and miR-138 expression in etoposide resistant RB cell lines and chemotherapy treated patient tumors compared to non-treated tumors was revealed by Real-Time PCR. Overexpression approaches were performed to analyze the effects of RARα on RB cell viability, apoptosis, proliferation and tumorigenesis. Besides, we addressed the effect of miR-138 overexpression on RB cell chemotherapy resistance. RESULTS: A binding between miR-138 and RARα was shown by dual luciferase reporter gene assay. The study presented revealed that RARα is downregulated in etoposide resistant RB cells, while miR-138 is endogenously upregulated. Opposing RARα and miR-138 expression levels were detectable in chemotherapy pre-treated compared to non-treated RB tumor specimen. Overexpression of RARα increases apoptosis levels and reduces tumor cell growth of aggressive etoposide resistant RB cells in vitro and in vivo. Overexpression of miR-138 in chemo-sensitive RB cell lines partly enhances cell viability after etoposide treatment. CONCLUSIONS: Our findings show that RARα acts as a tumor suppressor in retinoblastoma and is downregulated upon etoposide resistance in RB cells. Thus, RARα may contribute to the development and progression of RB chemo-resistance.

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