scholarly journals Distinct Nongenomic Signal Transduction Pathways Controlled by 17β-Estradiol Regulate DNA Synthesis and Cyclin D1 Gene Transcription in HepG2 Cells

2002 ◽  
Vol 13 (10) ◽  
pp. 3720-3729 ◽  
Author(s):  
Maria Marino ◽  
Filippo Acconcia ◽  
Francesco Bresciani ◽  
Alessandro Weisz ◽  
Anna Trentalance
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Estrogen Receptor ◽  
Protein Kinase ◽  
Dna Synthesis ◽  
Gene Transcription ◽  
Hepg2 Cells ◽  
Signal Transduction Pathways ◽  
Cyclin D ◽  
17Β Estradiol

Estrogens induce cell proliferation in target tissues by stimulating progression through the G1 phase of the cell cycle. Activation of cyclin D1 gene expression is a critical feature of this hormonal action. The existence of rapid/nongenomic estradiol-regulated protein kinase C (PKC-α) and extracellular signal-regulated kinase (ERK) signal transduction pathways, their cross talk, and role played in DNA synthesis and cyclin D1 gene transcription have been studied herein in human hepatoma HepG2 cells. 17β-Estradiol was found to rapidly activate PKC-α translocation and ERK-2/mitogen-activated protein kinase phosphorylation in this cell line. These actions were independent of each other, preceding the increase of thymidine incorporation into DNA and cyclin D1expression, and did not involve DNA binding by estrogen receptor. The results obtained with specific inhibitors indicated that PKC-α pathway is necessary to mediate the estradiol-induced G1-S progression of HepG2 cells, but it does not exert any effect(s) on cyclin D1 gene expression. On the contrary, ERK-2 cascade was strongly involved in both G1-S progression and cyclin D1gene transcription. Deletion of its activating protein-1 responsive element motif resulted in attenuation of cyclin D1 promoter responsiveness to estrogen. These results indicate that estrogen-induced cyclin D1 transcription can occur in HepG2 cells independently of the transcriptional activity of estrogen receptor, sustaining the pivotal role played by nongenomic pathways of estrogen action in hormone-induced proliferation.

In vivo regulation of growth hormone-stimulated gene transcription by STAT5b

2004 ◽  
Vol 286 (3) ◽  
pp. E393-E401 ◽  
Author(s):  
Joachim Woelfle ◽  
Peter Rotwein
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Growth Hormone ◽  
Gene Transfer ◽  
Gene Transcription ◽  
Dominant Negative ◽  
Signal Transduction Pathways ◽  
Igf I ◽  
Igfbp 3

The long-term effects of growth hormone (GH) are mediated through coordinated changes in gene expression that are the outcome of interactions between hormone-activated signal transduction pathways and specific feedback loops. Recent studies in mice have implicated the transcription factor STAT5b as part of the GH-regulated somatic growth pathway, because mice lacking this protein showed diminished growth rates. To assess the role of Stat5b in GH-stimulated gene expression, we have delivered modified versions of the protein to the liver of pituitary-deficient male rats by quantitative adenovirus-mediated gene transfer. In pilot studies in cell culture, both constitutive-active and dominant-negative STAT5b showed appropriate binding properties toward a specific DNA response element. After in vivo expression, neither protein prevented nuclear accumulation of STATs 1 and 3 in the liver. Dominant-negative STAT5b completely inhibited GH-stimulated transcription of genes encoding the growth-promoting proteins IGF-I, IGF-binding protein-3 (IGFBP-3), and acid-labile subunit (ALS), which comprise the major circulating IGF-I complex, and blocked expression of the GH inhibitors SOCS-1, SOCS-2, and CIS, but had little effect on induction of SOCS-3. Constitutive-active STAT5b stimulated robust transcription of IGF-I, ALS, and IGFBP-3 in the absence of hormone but did little to modify GH-mediated activation of SOCS family genes. An adenovirus encoding EGFP was without effect. These results, in addition to establishing STAT5b as one of the key agents of GH-stimulated gene transcription, demonstrate the feasibility of using in vivo gene transfer to target and dissect the functions of distinct components of complex hormone-activated signal transduction pathways.

scholarly journals Hormonal Regulation of Estrogen Receptor α and β Gene Expression in Human Granulosa-Luteal Cells in Vitro1

2000 ◽  
Vol 85 (10) ◽  
pp. 3828-3839 ◽  
Author(s):  
Chi-Hsin Chiang ◽  
Kwai Wa Cheng ◽  
Shigeo Igarashi ◽  
Parimal S. Nathwani ◽  
Peter C. K. Leung
Keyword(s):  
Gene Expression ◽  
Estrogen Receptor ◽  
Protein Kinase ◽  
Hormonal Regulation ◽  
Mrna Levels ◽  
Human Ovary ◽  
Rt Pcr ◽  
17Β Estradiol ◽  
Er Expression

Estrogen is one of the major sex steroid hormones that is produced from the human ovary, and its actions are established to be a receptor-mediated process. Despite the demonstration of estrogen receptor (ER) expression, little is known regarding the regulation of ER in the human ovary. In the present study we investigated the expression and hormonal regulation of ERα and ERβ in human granulosa-luteal cells (hGLCs). Using RT-PCR amplification, both ERα and ERβ messenger ribonucleic acid (mRNA) were detected from hGLCs. Northern blot analysis revealed that ERα is expressed at a relatively lower level than ERβ. Basal expression studies indicated that ERα mRNA levels remain unchanged, whereas ERβ mRNA levels increased with time in culture in vitro, suggesting that ERβ is likely to play a dynamic role in mediating estrogen action in hGLCs. The regulation of ERα and ERβ expression by hCG was examined. hCG treatment (10 IU/mL) significantly attenuated the ERα (45%; P < 0.01) and ERβ (40%; P< 0.01) mRNA levels. The hCG-induced decrease in ERα and ERβ expression was mimicked by 8-bromo-cAMP (1 mmol/L) and forskolin (10μ mol/L) treatment. Additional studies using a specific protein kinase A (PKA) inhibitor (adenosine 3′,5′-cyclic monophosphorothioate, Rp-isomer, triethylammonium salt) and an adenylate cyclase inhibitor (SQ 22536) further implicated the involvement of the cAMP/PKA signaling pathway in hCG action in these cells. The hCG-induced decrease in ERα and ERβ mRNA levels was prevented in the presence of these inhibitors. Next, the effect of GnRH on ER expression was studied. Sixty-eight percent (P < 0.001) and 60% (P < 0.001) decreases in ERα and ERβ mRNA levels, respectively, were observed after treatment with 0.1 μmol/L GnRH agonist (GnRHa). Pretreatment of the cells with a protein kinase C (PKC) inhibitor (GF109203X) completely reversed the GnRHainduced down-regulation of ERα and ERβ expression, suggesting the involvement of PKC in GnRH signal transduction in hGLCs. In agreement with the semiquantitative RT-PCR results, Western blot analysis detected a decrease in ERα and ERβ proteins levels in hGLCs after treatment with hCG (10 IU/mL), GnRH (0.1 μmol/L), 8-bromo-cAMP (1 mmol/L), forskolin (10 μmol/L), or phorbol 12-myristate 13 acetate (10 μmol/L). Functionally, we demonstrated an inhibition of progesterone production in hGLCs in vitro by 17β-estradiol, and this inhibitory effect was eliminated by pretreatment of 10 IU/mL hCG or 0.1 μmol/L GnRHa for 24 h before 17β-estradiol administration. In summary, we observed a differential expression of ERα and ERβ mRNA in hGLCs in vitro. The demonstration of hCG- and GnRHa-induced down-regulation of ERα and ERβ gene expression suggests that hCG and GnRH may contribute to the control of granulosa-luteal cell function. Furthermore, our data suggest that the effects of hCG and GnRH on ERα and ERβ expression in hGLCs are mediated in part by activation of PKA and PKC signaling pathways, respectively.

Nitric oxide increases IL-8 gene transcription and mRNA stability to enhance IL-8 gene expression in lung epithelial cells

2004 ◽  
Vol 287 (4) ◽  
pp. L764-L773 ◽  
Author(s):  
Loretta Sparkman ◽  
Vijayakumar Boggaram
Keyword(s):  
Gene Expression ◽  
Nitric Oxide ◽  
Protein Kinase ◽  
Epithelial Cells ◽  
Gene Transcription ◽  
Mrna Stability ◽  
Inflammatory Responses ◽  
Lung Epithelial Cells ◽  
Mrna Levels ◽  
Lung Epithelial

Interleukin (IL)-8, a C-X-C chemokine, is a potent chemoattractant and an activator for neutrophils, T cells, and other immune cells. The airway and respiratory epithelia play important roles in the initiation and modulation of inflammatory responses via production of cytokines and surfactant. The association between elevated levels of nitric oxide (NO) and IL-8 in acute lung injury associated with sepsis, acute respiratory distress syndrome, respiratory syncytial virus infection in infants, and other inflammatory diseases suggested that NO may play important roles in the control of IL-8 gene expression in the lung. We investigated the role of NO in the control of IL-8 gene expression in H441 lung epithelial cells. We found that a variety of NO donors significantly induced IL-8 mRNA levels, and the increase in IL-8 mRNA was associated with an increase in IL-8 protein. NO induction of IL-8 mRNA was due to increases in IL-8 gene transcription and mRNA stability. NO induction of IL-8 mRNA levels was not inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one and KT-5823, inhibitors of soluble guanylate cyclase and protein kinase G, respectively, and 8-bromo-cGMP did not increase IL-8 mRNA levels. This indicated that NO induces IL-8 mRNA levels independently of changes in the intracellular cGMP levels. NO induction of IL-8 mRNA was significantly reduced by inhibitors of extracellular regulated kinase and protein kinase C. IL-8 induction by NO was also reduced by hydroxyl radical scavengers such as dimethyl sulfoxide and dimethylthiourea, indicating the involvement of hydroxyl radicals in the induction process. NO induction of IL-8 gene expression could be a significant contributing factor in the initiation and induction of inflammatory response in the respiratory epithelium.

scholarly journals Iodide- and Glucose-Handling Gene Expression Regulated by Sorafenib or Cabozantinib in Papillary Thyroid Cancer

2015 ◽  
Vol 100 (5) ◽  
pp. 1771-1779 ◽  
Author(s):  
Maomei Ruan ◽  
Min Liu ◽  
Qianggang Dong ◽  
Libo Chen
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Signal Transduction ◽  
Cell Proliferation ◽  
Thyroid Cancer ◽  
Western Blot ◽  
Glucose Transporter ◽  
Signal Transduction Pathways ◽  
Papillary Thyroid ◽  
Cycle Arrest

Abstract Context: The aberrant silencing of iodide-handling genes accompanied by up-regulation of glucose metabolism presents a major challenge for radioiodine treatment of papillary thyroid cancer (PTC). Objective: This study aimed to evaluate the effect of tyrosine kinase inhibitors on iodide-handling and glucose-handling gene expression in BHP 2-7 cells harboring RET/PTC1 rearrangement. Main Outcome Measures: In this in vitro study, the effects of sorafenib or cabozantinib on cell growth, cycles, and apoptosis were investigated by cell proliferation assay, cell cycle analysis, and Annexin V-FITC apoptosis assay, respectively. The effect of both agents on signal transduction pathways was evaluated using the Western blot. Quantitative real-time PCR, Western blot, immunofluorescence, and radioisotope uptake assays were used to assess iodide-handling and glucose-handling gene expression. Results: Both compounds inhibited cell proliferation in a time-dependent and dose-dependent manner and caused cell cycle arrest in the G0/G1 phase. Sorafenib blocked RET, AKT, and ERK1/2 phosphorylation, whereas cabozantinib blocked RET and AKT phosphorylation. The restoration of iodide-handling gene expression and inhibition of glucose transporter 1 and 3 expression could be induced by either drug. The robust expression of sodium/iodide symporter induced by either agent was confirmed, and 125I uptake was correspondingly enhanced. 18F-fluorodeoxyglucose accumulation was significantly decreased after treatment by either sorafenib or cabozantinib. Conclusions: Sorafenib and cabozantinib had marked effects on cell proliferation, cell cycle arrest, and signal transduction pathways in PTC cells harboring RET/PTC1 rearrangement. Both agents could be potentially used to enhance the expression of iodide-handling genes and inhibit the expression of glucose transporter genes.

scholarly journals Identification of four novel phosphorylation sites in estrogen receptor alpha: impact on receptor-dependent gene expression and phosphorylation by protein kinase CK2.

2009 ◽  
Vol 10 (1) ◽  
pp. 36 ◽  
Author(s):  
Christopher C Williams ◽  
Aninda Basu ◽  
Abeer El-Gharbawy ◽  
Latonya M Carrier ◽  
Carolyn L Smith ◽  
...  
Keyword(s):  
Gene Expression ◽  
Estrogen Receptor ◽  
Protein Kinase ◽  
Protein Kinase Ck2 ◽  
Estrogen Receptor Alpha ◽  
Phosphorylation Sites ◽  
Receptor Alpha ◽  
Kinase Ck2
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