KLF4 positively regulates human ghrelin expression

2009 ◽  
Vol 420 (3) ◽  
pp. 403-411 ◽  
Author(s):  
Hyo Jung Lee ◽  
Young Mi Kang ◽  
Chang Suk Moon ◽  
Myung Kuk Joe ◽  
Joo Hyun Lim ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Human Gastric Cancer ◽  
Dependent Manner ◽  
Growth Hormone Secretagogue Receptor ◽  
Mobility Shift ◽  
Ags Cells ◽  
Growth Hormone Secretagogue ◽  
Gh Secretion ◽  
Klf4 Expression ◽  
Responsive Element

Ghrelin, an endogenous ligand of the GH (growth hormone) secretagogue receptor, influences many metabolic processes including GH secretion, food intake, energy balance, insulin secretion and adipogenesis. Although ghrelin exhibits a variety of biological functions, the mechanism by which ghrelin expression is regulated is unknown. Ghrelin is expressed in the gastrointestinal tract, predominantly in the stomach, as is KLF4 (Krüppel-like factor 4). Therefore we investigated whether ghrelin expression is associated with KLF4, and found that the tissue distribution of ghrelin corresponded with that of KLF4. Furthermore, treatment with butyrate, an inducer of KLF4 expression, stimulated ghrelin expression, and fasting, which induces ghrelin expression, also increased KLF4 expression, suggesting that ghrelin expression is associated with KLF4. Then, we investigated the effects of KLF4 on the human ghrelin-promoter activity and identified a KLF4-responsive region in the promoter. KLF4 expression specifically stimulated human ghrelin-promoter activity in a dose-dependent manner in human gastric-cancer AGS cells. However, this effect was not seen in response to a mutant KLF4 construct. Transfection studies using mutant constructs containing 5′-deletions in the human ghrelin promoter revealed that the KLF4-responsive element is located between −1228 and −1105. Electrophoretic mobility shift assays using oligonucleotides containing −1165/−1146 revealed the binding of KLF4 to the human ghrelin promoter. Finally, deletion of the −1165/−1146 region abrogated KLF4-induced transactivation of the ghrelin promoter. Collectively, these results indicate that KLF4 positively regulates human ghrelin expression via binding to a KLF-responsive region in the promoter.

scholarly journals Gastrin regulates the TFF2 promoter through gastrin-responsive cis-acting elements and multiple signaling pathways

2007 ◽  
Vol 292 (6) ◽  
pp. G1726-G1737 ◽  
Author(s):  
Shuiping Tu ◽  
Alfred L. Chi ◽  
SeonHee Lim ◽  
Guanglin Cui ◽  
Zina Dubeykovskaya ◽  
...  
Keyword(s):  
Dna Binding ◽  
Promoter Activity ◽  
Growth Factor Receptor ◽  
Gastric Cancer Cell Line ◽  
Cancer Cell Line ◽  
Gastric Fundus ◽  
Luciferase Reporter ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Cis Acting

Trefoil family factor 2 (TFF2) is expressed in gastrointestinal epithelial cells where it serves to maintain mucosal integrity and promote epithelial repair. The peptide hormone, gastrin, stimulates acid secretion but also induces proliferation of the acid-secreting mucosa. Because the relationship between these peptides of overlapping function is not understood, we chose to investigate the regulatory effect of gastrin on TFF2 expression. The expression of mRNA and protein of TFF2 was determined by RT-PCR and immunohistochemical staining, respectively. A series of truncated and mutant murine TFF2 promoter constructs was generated. Promoter activity was assessed using dual luciferase reporter assays. Gastrin-responsive DNA-binding sites in the TFF2 promoter were evaluated by electrophoretic mobility shift assay. Gastrin significantly increased the level of endogenous mRNA of TFF2 in the gastrin receptor-expressing AGS-E gastric cancer cell line in a time- and dose-dependent manner. TFF2 protein expression in the gastric fundus was elevated in hypergastrinemic (INS-GAS) transgenic mice and reduced in gastrin-deficient mice. Gastrin treatment increased TFF2 promoter activity through cis-acting regions, containing CCAATA- and GC-rich enhancers. Pretreatment with Y-F476, a gastrin/CCKB receptor antagonist, abolished gastrin-dependent promoter activity. Inhibitors of protein kinase C (PKC), mitogen/extracellular signal-regulated kinase (MEK1), and phosphatidylinositol 3-kinase (PI 3-kinase) reduced gastrin-dependent TFF2 promoter activity, whereas an epithelial growth factor receptor (EGFR) inhibitor had no effect. We found that gastrin regulates TFF2 transcription through a GC-rich DNA-binding site and a PKC-, MEK1- and PI 3-kinase-dependent but EGFR-independent pathway. Regulation of TFF2 by gastrin may play a role in the maintenance and repair of the gastrointestinal mucosa.

scholarly journals Tpl2/AP-1 Enhances Murine Gammaherpesvirus 68 Lytic Replication

2009 ◽  
Vol 84 (4) ◽  
pp. 1881-1890 ◽  
Author(s):  
Xudong Li ◽  
Jun Feng ◽  
Shijia Chen ◽  
Li Peng ◽  
Wei-Wu He ◽  
...  
Keyword(s):  
Gene Expression ◽  
Promoter Activity ◽  
Lytic Replication ◽  
Dependent Manner ◽  
Lytic Gene ◽  
Murine Gammaherpesvirus ◽  
Gammaherpesvirus 68 ◽  
Responsive Element ◽  
Murine Gammaherpesvirus 68 ◽  
Lytic Genes

ABSTRACT How cellular factors regulate gammaherpesvirus lytic replication is not well understood. Here, through functional screening of a cellular kinase expression library, we identified mitogen-activated protein kinase kinase kinase 8 (MAP3K8/Tpl2) as a positive regulator of murine gammaherpesvirus 68 (MHV-68 or γHV-68) lytic gene expression and replication. Tpl2 enhances MHV-68 lytic replication by upregulating lytic gene expression and promoter activities of viral lytic genes, including RTA and open reading frame 57 (ORF57). By screening a cellular transcription factor library, we identified the Fos AP-1 transcription factor as a downstream factor that is both necessary and sufficient for mediating the enhancement of MHV-68 lytic replication by Tpl2. In addition, Tpl2 stimulates the promoter activities of key viral lytic genes, including RTA and ORF57, in an AP-1-dependent manner. We identified an AP-1-responsive element on the MHV-68 RTA promoter as the cis element mediating the upregulation of RTA promoter activity by Tpl2. MHV-68 lytic infection upregulates Fos expression, AP-1 activity, and RTA promoter activity in a Tpl2-dependent manner. We constructed a mutant MHV-68 virus that abolished this AP-1-responsive element. This mutant virus exhibited attenuated lytic replication kinetics, indicative of a critical role of this AP-1-responsive element during lytic replication. Moreover, Tpl2 knockdown inhibited the lytic replication of wild-type MHV-68 (MHV-68-WT) but not that of the MHV-68 mutant virus, indicating that endogenous Tpl2 promotes efficient virus lytic replication through AP-1-dependent upregulation of RTA expression. In summary, through tandem functional screens, we identified the Tpl2/AP-1 signaling transduction pathway as a positive regulator of MHV-68 lytic replication.

scholarly journals Ghrelin and Des-Octanoyl Ghrelin Promote Adipogenesis Directly in Vivo by a Mechanism Independent of the Type 1a Growth Hormone Secretagogue Receptor

Endocrinology ◽  
2004 ◽  
Vol 145 (1) ◽  
pp. 234-242 ◽  
Author(s):  
Nichola M. Thompson ◽  
Dave A. S. Gill ◽  
Rhos Davies ◽  
Nigel Loveridge ◽  
Pamela A. Houston ◽  
...  
Keyword(s):  
Gh Deficiency ◽  
Pituitary Hormones ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Rat Models ◽  
Gh Secretion ◽  
Peripheral Action ◽  
Adipogenic Effect ◽  
Stimulation Of

Abstract Ghrelin promotes fat accumulation, despite potent stimulation of the lipolytic hormone, GH. The function of the major circulating isoform of ghrelin, des-octanoyl ghrelin, is unclear, because it does not activate the GH secretagogue receptor (GHS-R1a) and lacks the endocrine activities of ghrelin. We have now addressed these issues by infusing ghrelin, des-octanoyl ghrelin, or synthetic GHS-R1a agonists into three rat models with moderate, severe, or total GH deficiency. We show that in the context of significant GH secretion, the adipogenic effect of systemic ghrelin infusion is pattern dependent. However, this adipogenic action is not mediated by the pituitary hormones. Using a novel unilateral local infusion strategy, we demonstrate that ghrelin promotes bone marrow adipogenesis in vivo by a direct peripheral action. Surprisingly, this effect was also observed with des-octanoyl ghrelin, whereas a potent synthetic GHS-R1a agonist was ineffective. Thus, these adipogenic effects are mediated by a receptor other than GHS-R1a. This is the first in vivo demonstration of a direct adipogenic effect of des-octanoyl ghrelin, a major circulating form of ghrelin that lacks GH-releasing activity. We suggest that the ratio of ghrelin and des-octanoyl ghrelin production could help regulate the balance between adipogenesis and lipolysis in response to nutritional status.

scholarly journals Regulation of the nitrate reductase operon narKGHJI by the cAMP-dependent regulator GlxR in Corynebacterium glutamicum

Microbiology ◽  
2011 ◽  
Vol 157 (1) ◽  
pp. 21-28 ◽  
Author(s):  
Taku Nishimura ◽  
Haruhiko Teramoto ◽  
Koichi Toyoda ◽  
Masayuki Inui ◽  
Hideaki Yukawa
Keyword(s):  
Nitrate Reductase ◽  
Binding Site ◽  
Corynebacterium Glutamicum ◽  
Promoter Region ◽  
Promoter Activity ◽  
Reductase Activity ◽  
Receptor Protein ◽  
Binding Motif ◽  
Dependent Manner ◽  
Mobility Shift

The Corynebacterium glutamicum anaerobic nitrate reductase operon narKGHJI is repressed by a transcriptional regulator, ArnR, under aerobic conditions. A consensus binding site of the cAMP receptor protein (CRP)-type regulator, GlxR, was recently found upstream of the ArnR binding site in the narK promoter region. Here we investigated the involvement of GlxR and cAMP in expression of the narKGHJI operon in vivo. Electrophoretic mobility shift assays showed that the putative GlxR binding motif in the narK promoter region is essential for the cAMP-dependent binding of GlxR. Promoter-reporter assays showed that mutation in the GlxR binding site resulted in significant reduction of narK promoter activity. Furthermore, a deletion mutant of the adenylate cyclase gene cyaB, which is involved in cAMP synthesis, exhibited a decrease in both narK promoter activity and nitrate reductase activity. These results demonstrated that C. glutamicum GlxR positively regulates narKGHJI expression in a cAMP-dependent manner.

Effect of chronic hyperghrelinemia on ingestive action of ghrelin

2006 ◽  
Vol 290 (3) ◽  
pp. R803-R808 ◽  
Author(s):  
Wei Wei ◽  
Xiang Qi ◽  
Jason Reed ◽  
Jeff Ceci ◽  
Hui-Qun Wang ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Transgenic Mice ◽  
Growth Response ◽  
Fat Pad ◽  
Endogenous Ligand ◽  
Growth Hormone Secretagogue Receptor ◽  
Growth Hormone Secretagogue ◽  
Gh Secretion ◽  
Ghrelin Gene

The stomach hormone ghrelin is the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). Systemic administration of ghrelin will cause elevations in growth hormone (GH) secretion, food intake, adiposity, and body growth. Ghrelin also affects insulin secretion, gastric acid secretion, and gastric motility. Several reports indicate that repeated or continuous activation of GHS-R by exogenous GHSs or ghrelin results in a diminished GH secretory response. The purpose of this study was to examine the extent to which the acute stimulation of food intake by exogenous ghrelin is altered by chronic hyperghrelinemia in transgenic mice that overexpress the human ghrelin gene. The present findings show that the orexigenic action of exogenous ghrelin is not diminished by a chronic hyperghrelinemia and indicate that the food ingestive pathway of the GHS-R is not susceptible to desensitization. In contrast, the epididymal fat pad growth response, like the GH response, to exogenous ghrelin is blunted in ghrelin transgenic mice with chronic hyperghrelinemia.

scholarly journals Helicobacter pylori Activates the Early Growth Response 1 Protein in Gastric Epithelial Cells

2004 ◽  
Vol 72 (6) ◽  
pp. 3549-3560 ◽  
Author(s):  
M. M. M. Abdel-Latif ◽  
H. J. Windle ◽  
K. A. Fitzgerald ◽  
Y. S. Ang ◽  
D. Ní Eidhin ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Growth Response ◽  
Early Growth ◽  
Dependent Manner ◽  
Mobility Shift ◽  
Ags Cells ◽  
Early Growth Response ◽  
H Pylori ◽  
Early Growth Response 1

ABSTRACT The early growth response 1 (Egr-1) transcription factor is rapidly induced by various stimuli and is implicated in the regulation of cell growth, differentiation, and gene expression. The aim of this study was to examine the effect of Helicobacter pylori on the expression of Egr-1 and Egr-1-regulated genes in gastric epithelial AGS cells. Egr-1 expression was assayed by immunoblotting and electrophoretic mobility shift assays using H. pylori-stimulated AGS cells. Transient transfection experiments with promoter-reporter constructs of CD44, ICAM-1, and CD95L were used for expression studies. H. pylori induced the expression of Egr-1 in gastric epithelial cell lines in a dose-dependent manner, with the rapid kinetics that are typical of this class of transcription factors. Immunohistochemical studies of biopsies revealed that Egr-1 expression is more abundant in H. pylori-positive patients than in uninfected individuals. Reporter-promoter transfection studies indicated that Egr-1 binding is required for the H. pylori-induced transcriptional promoter activity of the CD44, ICAM-1, and CD95L (APO-1/Fas) constructs. The blocking of egr-1 with an antisense sequence prevented H. pylori-induced Egr-1 and CD44 protein expression. The MEK1/2 signaling cascade participates in H. pylori-mediated Egr-1 expression, but the p38 pathway does not. The data indicate that H. pylori induces Egr-1 expression in AGS cells in vitro and that the Egr-1 protein is readily detectable in biopsies from H. pylori-positive subjects. These observations suggest that H. pylori-associated Egr-1 expression may play a role, in part, in H. pylori-induced pathology.

scholarly journals RmpA Regulation of Capsular Polysaccharide Biosynthesis in Klebsiella pneumoniae CG43

2010 ◽  
Vol 192 (12) ◽  
pp. 3144-3158 ◽  
Author(s):  
H. Y. Cheng ◽  
Y. S. Chen ◽  
C. Y. Wu ◽  
H. Y. Chang ◽  
Y. C. Lai ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Promoter Activity ◽  
Deletion Mutant ◽  
Capsular Polysaccharide ◽  
Activity Measurement ◽  
Virulence Plasmid ◽  
Dependent Manner ◽  
Multicopy Plasmid ◽  
Regulatory Activity ◽  
Mobility Shift

ABSTRACT Sequence analysis of the large virulence plasmid pLVPK in Klebsiella pneumoniae CG43 revealed the presence of another mucoid factor encoding gene rmpA besides rmpA2. Promoter activity measurement indicated that the deletion of rmpA reduced K2 capsular polysaccharide (CPS) biosynthesis, resulting in decreased colony mucoidy and virulence in mice. Introduction of a multicopy plasmid carrying rmpA restored CPS production in the rmpA or rmpA2 mutant but not in the rcsB mutant. Transformation of the rmpA deletion mutant with an rcsB-carrying plasmid also failed to enhance CPS production, suggesting that a cooperation of RmpA with RcsB is required for regulatory activity. This was further corroborated by the demonstration of in vivo interaction between RmpA and RcsB using two-hybrid analysis and coimmunoprecipitation analysis. A putative Fur binding box was only found at the 5′ noncoding region of rmpA. The promoter activity analysis indicated that the deletion of fur increased the rmpA promoter activity. Using electrophoretic mobility shift assay, we further demonstrated that Fur exerts its regulatory activity by binding directly to the promoter. As a result, the fur deletion mutant exhibited an increase in colony mucoidy, CPS production, and virulence in mice. In summary, our results suggested that RmpA activates CPS biosynthesis in K. pneumoniae CG43 via an RcsB-dependent manner. The expression of rmpA is regulated by the availability of iron and is negatively controlled by Fur.

Benzyl isothiocyanate (BITC) inhibits migration and invasion of human gastric cancer AGS cells via suppressing ERK signal pathways

2010 ◽  
Vol 30 (4) ◽  
pp. 296-306 ◽  
Author(s):  
Chin-Chin Ho ◽  
Kuang-Chi Lai ◽  
Shu-Chun Hsu ◽  
Chao-Lin Kuo ◽  
Chia-Yu Ma ◽  
...  
Keyword(s):  
Gastric Cancer ◽  
Cancer Cells ◽  
Inhibitory Effect ◽  
Laboratory Animals ◽  
Migration And Invasion ◽  
Signal Pathways ◽  
Human Gastric Cancer ◽  
Dependent Manner ◽  
Ags Cells ◽  
Benzyl Isothiocyanate

Metastasis suppressors and associated other regulators of cell motility play a critical initial role in tumor invasion and metastases. Benzyl isothiocyanate (BITC) is a hydrolysis compound of glucotropaeolin in dietary cruciferous vegetables. BITC has been found to exhibit prevention of cancers in laboratory animals and might also be chemoprotective in humans. Here, the purpose of this study was to investigate the effects of BITC on cell proliferation, migration, invasion and mitogen-activated protein kinase (MAPK) pathways of AGS human gastric cancer cells. Wound healing and Boyden chamber (migration and invasion) assays demonstrated that BITC exhibited an inhibitory effect on the abilities of migration and invasion in AGS cancer cells. BITC suppressed cell migration and invasion of AGS cells in a dose-dependent manner. Results from Western blotting indicated that BITC exerted an inhibitory effect on the ERK1/2, Ras, GRB2, Rho A, iNOS, COX-2 for causing the inhibitions of MMP-2, -7 and -9 then followed by the inhibitions of invasion and migration of AGS cells in vitro. BITC also promoted MKK7, MEKK3, c-jun, JNK1/2, VEGF, Sos1, phosphoinositide 3-kinase (PI3K), PKC, nuclear factor-kappaB (NF-κB) p65 in AGS cells. Results from real-time polymerized chain reaction (PCR) showed that BITC inhibited the gene expressions of MMP-2,-7 -9, FAK, ROCK1 and RhoA after BITC treatment for 24 and 48 hours in AGS cells. Taken together, the finding may provide new mechanisms and functions of BITC, which inhibit migration and invasion of human gastric cancer AGS cells.

Fourth ventricular administration of ghrelin induces relaxation of the proximal stomach in the rat

2009 ◽  
Vol 296 (2) ◽  
pp. R217-R223 ◽  
Author(s):  
Motoi Kobashi ◽  
Mamoru Yanagihara ◽  
Masako Fujita ◽  
Yoshihiro Mitoh ◽  
Ryuji Matsuo
Keyword(s):  
Fourth Ventricle ◽  
Proximal Part ◽  
Dependent Manner ◽  
Growth Hormone Secretagogue Receptor ◽  
Proximal Stomach ◽  
Growth Hormone Secretagogue ◽  
Significant Change ◽  
Intermediate Part ◽  
Dose Dependent ◽  
Cervical Level

The effects of fourth ventricular administration of ghrelin on motility of the proximal stomach were examined in anesthetized rats. Intragastric pressure (IGP) was measured using a balloon situated in the proximal part of the stomach. Administration of ghrelin into the fourth ventricle induced relaxation of the proximal stomach in a dose-dependent manner. Significant reduction of IGP was observed at doses of 3, 10, or 30 pmol. The administration of ghrelin (10 or 30 pmol) with growth hormone secretagogue receptor (GHS-R) antagonist ([d-Lys3] GHRP-6; 1 nmol) into the fourth ventricle did not induce a significant change in IGP. The sole administration of [d-Lys3] GHRP-6 also did not induce a significant change in IGP. Bilateral sectioning of the vagi at the cervical level abolished the relaxation induced by the administration of ghrelin (10 or 30 pmol) into the fourth ventricle, suggesting that relaxation induced by ghrelin is mediated by vagal preganglionic neurons. Microinjections of ghrelin (200 fmol) into the caudal part of the dorsal vagal complex (DVC) induced obvious relaxation of the proximal stomach. Similar injections into the intermediate part of the DVC did not induce significant change. Dose-response analyses revealed that the microinjection of 2 fmol of ghrelin into the caudal DVC significantly reduced IGP. These results revealed that ghrelin induced relaxation in the proximal stomach via GHS-R situated in the caudal DVC.

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