scholarly journals Comparison of 7α-methyl-19-nortestosterone effectiveness alone or combined with progestins on androgen receptor mediated-transactivation

Reproduction ◽  
2012 ◽  
Vol 143 (2) ◽  
pp. 211-219 ◽  
Author(s):  
Rocío García-Becerra ◽  
David Ordaz-Rosado ◽  
Gabriela Noé ◽  
Bertha Chávez ◽  
Austin J Cooney ◽  
...  
Keyword(s):  
Gene Expression ◽  
Androgen Receptor ◽  
Reporter Gene ◽  
Gene Transcription ◽  
Detrimental Effect ◽  
Synergistic Effects ◽  
Estrogen Receptor Α ◽  
Male Contraceptive ◽  
Estrogen Activity ◽  
Dose Dependent

7α-methyl-19-nortestosterone (MENT) is an androgen with potent gonadotropin inhibitory activity and prostate-sparing effects. These attributes give MENT advantages over testosterone as a male contraceptive, but, as in the case of testosterone, a partial dose-dependent suppression of spermatogenesis has been observed. Combination of testosterone or MENT with synthetic progestins improves the rate of azoospermia; however, it is unknown whether these combinations affect hormone androgenicity or exert synergistic effects via progestational or androgenic interaction. Herein, using transactivation assays, we examined the ability of MENT alone or combined with several 19-nor-derived synthetic progestins to activate androgen receptor (AR)-dependent gene transcription. In addition, the capability of 7α-methyl-estradiol (7α-methyl-E2), an aromatized metabolite of MENT, to transactivate gene transcription via estrogen receptor α (ERα; ESR1) or ERβ (ESR2) was also investigated. As expected, MENT induced gene transactivation through either the progesterone receptor (PGR) or the AR. MENT was as efficient as progesterone in activating PGR-mediated reporter gene expression, but it was ten times more potent than testosterone and dihydrotestoterone in activating of AR-driven gene expression. The addition of increasing concentrations of other 19-nortestosterone derivatives (norethisterone or levonorgestrel) did not affect, in a significant manner, the ability of MENT to activate AR-dependent reporter gene transcription. The same results were obtained with different cell lines. 7α-Methyl-E2 resulted in potent estrogen activity via both ER subtypes with efficiency similar to natural E2. These results suggest that the addition of 19-nortestosterone-derived progestins, as a hormonal adjuvant in male fertility strategies for effective spermatogenic suppression, does not display any detrimental effect that would interfere with MENT androgenic transcriptional activity.

Inhibition of mitochondrial gene transcription suppresses neurotensin secretion in the human carcinoid cell line BON

2005 ◽  
Vol 288 (2) ◽  
pp. G213-G220 ◽  
Author(s):  
Nan Li ◽  
Qingding Wang ◽  
Jing Li ◽  
Xiaofu Wang ◽  
Mark R. Hellmich ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Line ◽  
Gene Transcription ◽  
Mitochondrial Gene ◽  
Intestinal Cell ◽  
N Gene ◽  
Cell Cycle Distribution ◽  
Dependent Manner ◽  
Mitochondrial Gene Expression ◽  
Dose Dependent

Mitochondria, organelles essential for ATP production, play a central role in a number of cellular functions, including the regulation of insulin secretion. Neurotensin (NT), an important regulatory intestinal hormone, has been implicated in fatty acid translocation, gut motility and secretion, and intestinal cell growth; however, mechanisms regulating NT secretion have not been entirely defined. The purpose of this study was to determine the effect of inhibition of mitochondrial gene transcription on NT secretion. BON cells, a novel human carcinoid cell line that produces and secretes NT peptide and expresses the gene encoding NT (designated NT/N), were treated with ethidium bromide (EB; 0.05, 0.1, and 0.4 μg/ml), an inhibitor of DNA and RNA synthesis, or vehicle over a time course (1–4 days). Cells were then stimulated with either ACh (100 μM) or phorbol 12 myristate,13-acetate (PMA, 10 nM) for 30 min. Media and cells were extracted, and NT peptide measured by RIA. Treatment with EB had no effect on BON cell viability or cell cycle distribution over the 4-day course. In contrast, EB treatment produced a dose-dependent reduction of mitochondrial gene expression; however, NT/N gene expression was not altered. Mitochondrial inhibition by EB treatment suppressed NT secretion induced by ACh and PMA, both in a dose-dependent manner. EB-mediated inhibition of NT secretion and mitochondrial gene expression was reversed with removal of EB. Our results demonstrate that inhibition of mitochondrial gene transcription suppresses both ACh- and PMA-stimulated NT release. These findings are the first to demonstrate that mitochondrial function is important for agonist-mediated NT secretion.

scholarly journals cAMP prevents the glucose-mediated stimulation of GLUT2 gene transcription in hepatocytes

1997 ◽  
Vol 322 (2) ◽  
pp. 441-448 ◽  
Author(s):  
Franck RENCUREL ◽  
Gérard WAEBER ◽  
Christophe BONNY ◽  
Bénédicte ANTOINE ◽  
Paulette MAULARD ◽  
...  
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Gene Transcription ◽  
Glucose Transporter ◽  
Hepatoma Cell ◽  
Inhibitory Effect ◽  
Hepatoma Cell Line ◽  
Mrna Accumulation ◽  
Glut2 Gene

Glucose homoeostasis necessitates the presence in the liver of the high Km glucose transporter GLUT2. In hepatocytes, we and others have demonstrated that glucose stimulates GLUT2 gene expression in vivo and in vitro. This effect is transcriptionally regulated and requires glucose metabolism within the hepatocytes. In this report, we further characterized the cis-elements of the murine GLUT2 promoter, which confers glucose responsiveness on a reporter gene coding the chloramphenicol acetyl transferase (CAT) gene. 5´-Deletions of the murine GLUT2 promoter linked to the CAT reporter gene were transfected into a GLUT2 expressing hepatoma cell line (mhAT3F) and into primary cultured rat hepatocytes, and subsequently incubated at low and high glucose concentrations. Glucose stimulates gene transcription in a manner similar to that observed for the endogenous GLUT2 mRNA in both cell types; the -1308 to -212 bp region of the promoter contains the glucose-responsive elements. Furthermore, the -1308 to -338 bp region of the promoter contains repressor elements when tested in an heterologous thymidine kinase promoter. The glucose-induced GLUT2 mRNA accumulation was decreased by dibutyryl-cAMP both in mhAT3F cells and in primary hepatocytes. A putative cAMP-responsive element (CRE) is localized at the -1074/-1068 bp region of the promoter. The inhibitory effect of cAMP on GLUT2 gene expression was observed in hepatocytes transfected with constructs containing this CRE (-1308/+49 bp fragment), as well as with constructs not containing the consensus CRE (-312/+49 bp fragment). This suggests that the inhibitory effect of cAMP is not mediated by the putative binding site located in the repressor fragment of the GLUT2 promoter. Taken together, these data demonstrate that the elements conferring glucose and cAMP responsiveness on the GLUT2 gene are located within the -312/+49 region of the promoter.

In vitro regulation of reporter gene transcription by the androgen receptor AF1 domain

2004 ◽  
Vol 32 (6) ◽  
pp. 1103-1106 ◽  
Author(s):  
M.A. Choudhry ◽  
I.J. McEwan
Keyword(s):  
Gene Expression ◽  
Androgen Receptor ◽  
Reporter Gene ◽  
Protein Interactions ◽  
Transcription Initiation ◽  
Muscular Atrophy ◽  
Activation Function ◽  
Regulation Of Transcription ◽  
Gene Assay

The androgen receptor (AR) is a ligand-activated transcription factor that regulates gene expression in response to the steroids testosterone and dihydrotestosterone. AR-dependent gene expression is likely to play an important role in a number of receptor-associated disorders, such as prostate cancer, spinal bulbar muscular atrophy, male type baldness and hirsutism. The AR contains two transactivation domains, termed AF1 (activation function 1) located in the N-terminus and AF2 (activation function 2) in the C-terminal ligand-binding domain. AF2 exhibits weak transcriptional activity, whereas AF1 is a strong regulator of transcription. Transcriptional regulation by AF1 is thought to be modulated by a number of proteins that interact with this region, and by post-translational modifications. Our focus is on the N-terminal-interacting proteins and their regulation of transcription via interaction with the receptor. To better understand the mechanism of AR-AF1 action, we have reconstituted AR activity in HeLa nuclear extracts using a unique dual reporter gene assay. Multiple LexA-binding sites in the promoter allow transcription to be driven by a recombinant AR-AF1–Lex fusion protein. The findings from initial experiments suggest an increase in transcription initiation and elongation rates by AR-AF1–Lex. The role of protein–protein interactions involving co-activators and basal transcription factors and AR-AF1 activity are discussed.

scholarly journals Androgen stimulates endothelial cell proliferation via an androgen receptor/VEGF/cyclin A-mediated mechanism

2011 ◽  
Vol 300 (4) ◽  
pp. H1210-H1221 ◽  
Author(s):  
Jingjing Cai ◽  
Yuan Hong ◽  
Chunyan Weng ◽  
Chen Tan ◽  
Julianne Imperato-McGinley ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Androgen Receptor ◽  
Endothelial Cell ◽  
Cyclin D1 ◽  
Cyclin A ◽  
Endothelial Cell Proliferation ◽  
Dependent Manner ◽  
Dose Dependent ◽  
Cardiovascular Functions

Growing evidences support that androgen displays beneficial effects on cardiovascular functions although the mechanism of androgen actions remains to be elucidated. Modulation of endothelial cell growth and function is a potential mechanism of androgen actions. We demonstrated in the present study that androgens [dihydrotestosterone (DHT) and testosterone], but not 17β-estradiol, produced a time- and dose-dependent induction of cell proliferation in primary human aortic endothelial cells (HAECs) as evident by increases in viable cell number and DNA biosynthesis. Real-time qRT-PCR analysis showed that DHT induced androgen receptor (AR), cyclin A, cyclin D1, and vascular endothelial growth factor (VEGF) gene expression in a dose- and time-dependent manner. The addition of casodex, a specific AR antagonist, or transfection of a specific AR siRNA blocked DHT-induced cell proliferation and target gene expression, indicating that the DHT effects are mediated via AR. Moreover, coadministration of SU5416 to block VEGF receptors, or transfection of a specific VEGF-A siRNA to knockdown VEGF expression, produced a dose-dependent blockade of DHT induction of cell proliferation and cyclin A gene expression. Interestingly, roscovitine, a selective cyclin-dependent kinase inhibitor, also blocked the DHT stimulation of cell proliferation with a selective inhibition of DHT-induced VEGF-A expression. These results indicate that androgens acting on AR stimulate cell proliferation through upregulation of VEGF-A, cyclin A, and cyclin D1 in HAECs, which may be beneficial to cardiovascular functions since endothelial cell proliferation could assist the repair of endothelial injury/damage in cardiovascular system.

scholarly journals Activated Androgen Receptor Downregulates E-Cadherin Gene Expression and Promotes Tumor Metastasis

2008 ◽  
Vol 28 (23) ◽  
pp. 7096-7108 ◽  
Author(s):  
Yan-Nian Liu ◽  
Ying Liu ◽  
Han-Jung Lee ◽  
Yung-Hsiang Hsu ◽  
Ji-Hshiung Chen
Keyword(s):  
Breast Cancer ◽  
Gene Expression ◽  
Androgen Receptor ◽  
Tumor Metastasis ◽  
Epithelial Mesenchymal Transition ◽  
Synergistic Effects ◽  
Cell Junction ◽  
Breast Cancer Patients ◽  
Mesenchymal Transition ◽  
E Cadherin

ABSTRACT The loss of E-cadherin gene expression can cause the dysfunction of the cell-cell junction to trigger tumor metastasis. Members of the Snail family of transcription factors are repressors of the expression of the E-cadherin gene. In this study, we showed that the activated androgen receptor (AR) is a novel repressor of E-cadherin gene expression and can promote metastasis. Our results demonstrated that the activated AR could bind to the E-cadherin promoter in vitro and in vivo. The activated AR and HDAC1 had synergistic effects in downregulating E-cadherin gene expression. Treating cells with the AR ligand, dihydrotestosterone (DHT), triggered the reduction of E-cadherin expression and induced changes in cell morphology from an epithelial-like to a mesenchymal-like appearance. When nonmetastatic breast cancer cells expressing cytoplasmic AR were transplanted into mice and the mice were treated with DHT, tumors were detected at metastatic sites, whereas no tumors were detected in transplanted mice without DHT treatment. Furthermore, clinical data from breast cancer patients with invasive ductal carcinomas showed high levels of AR expression in the nuclei and low levels of E-cadherin expression. These results suggest that, similarly to Snail and Twist, the activated AR can downregulate E-cadherin expression to promote the activation of epithelial-mesenchymal transition and tumor metastasis.

scholarly journals A Synthetic Riboswitch to Regulate Haloarchaeal Gene Expression

2021 ◽  
Vol 12 ◽  
Author(s):  
Johannes Born ◽  
Kerstin Weitzel ◽  
Beatrix Suess ◽  
Felicitas Pfeifer
Keyword(s):  
Gene Expression ◽  
Reporter Gene ◽  
Culture Media ◽  
Fold Increase ◽  
Start Codon ◽  
Genetic Circuit ◽  
Genetic Circuits ◽  
Domains Of Life ◽  
Dose Dependent ◽  
Ribosomal Binding Site

In recent years, synthetic riboswitches have become increasingly important to construct genetic circuits in all three domains of life. In bacteria, synthetic translational riboswitches are often employed that modulate gene expression by masking the Shine-Dalgarno (SD) sequence in the absence or presence of a cognate ligand. For (halo-)archaeal translation, a SD sequence is not strictly required. The application of synthetic riboswitches in haloarchaea is therefore limited so far, also because of the molar intracellular salt concentrations found in these microbes. In this study, we applied synthetic theophylline-dependent translational riboswitches in the archaeon Haloferax volcanii. The riboswitch variants A through E and E∗ were chosen since they not only mask the SD sequence but also the AUG start codon by forming a secondary structure in the absence of the ligand theophylline. Upon addition of the ligand, the ribosomal binding site and start codon become accessible for translation initiation. Riboswitch E mediated a dose-dependent, up to threefold activation of the bgaH reporter gene expression. Raising the salt concentration of the culture media from 3 to 4 M NaCl resulted in a 12-fold increase in the switching capacity of riboswitch E, and switching activity increased up to 26-fold when the cultivating temperature was reduced from 45 to 30°C. To construct a genetic circuit, riboswitch E was applied to regulate the synthesis of the transcriptional activator GvpE allowing a dose-dependent activation of the mgfp6 reporter gene under PpA promoter control.

Sign in / Sign up

Export Citation Format

Share Document