scholarly journals Glycated albumin upregulates upstream stimulatory factor 2 gene transcription in mesangial cells

2010 ◽  
Vol 299 (1) ◽  
pp. F121-F127 ◽  
Author(s):  
Yanzhang Li ◽  
Shuxia Wang
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Mesangial Cells ◽  
Glycated Albumin ◽  
Diabetic Patients ◽  
Dependent Manner ◽  
Upstream Stimulatory Factor ◽  
Protein Levels ◽  
Glycated Proteins ◽  
Stimulatory Factor

Diabetic nephropathy (DN) is the most common cause of end-stage renal failure. We previously demonstrated that a transcription factor called upstream stimulatory factor 2 (USF2) was upregulated in the kidneys from diabetic animals in vivo as well as in mesangial cells (MCs) exposed to high-glucose media in vitro. USF2 mediates glucose-induced thrombospondin 1 expression and transforming growth factor-β activity in MCs and plays a role in DN. Glycated proteins have been shown to accumulate in the kidneys of diabetic patients and contribute to DN. However, whether glycated proteins regulate USF2 expression in MCs and play a role in DN is unknown. In the present studies, we determined the effect of glycated albumin on UFS2 gene expression in primary rat MCs. We found that glycated albumin upregulated USF2 expression (mRNA and protein) in a dose- and time-dependent manner. We also demonstrated that glycated albumin stimulated USF2 gene expression at the transcriptional level. By using the luciferase-promoter deletion assay, site-directed mutagenesis, and transactivation assay, we identified a glycated albumin-responsive region in the USF2 gene promoter (−837 to −430, relative to the transcription start site) and demonstrated that glycated albumin-induced USF2 expression was mediated through NF-κB-dependent transactivation of the USF2 promoter. Furthermore, glycated albumin increased nuclear NF-κB subunit-p65 protein levels. siRNA-mediated p65 knockdown prevented glycated albumin-induced USF2 gene expression (promoter activity, mRNA, and protein levels). Taken together, these data suggest that glycated albumin upregulated USF2 gene transcription in MCs through NF-κB-dependent transactivation of the USF2 promoter.

scholarly journals Upstream stimulatory factor regulates Pdx-1 gene expression in differentiated pancreatic β-cells

1999 ◽  
Vol 341 (2) ◽  
pp. 315-322 ◽  
Author(s):  
Jin QIAN ◽  
Elizabeth N. KAYTOR ◽  
Howard C. TOWLE ◽  
L. Karl OLSON
Keyword(s):  
Gene Expression ◽  
Gene Promoter ◽  
Dominant Negative ◽  
Mrna Levels ◽  
Upstream Stimulatory Factor ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Protein Levels ◽  
E Box ◽  
Stimulatory Factor

The homeobox gene Pdx-1 plays a key role in the development of the pancreas. In the adult, however, expression of the Pdx-1 gene is restricted to pancreatic β-cells and endocrine cells of duodenal epithelium. Recently, the transcription factor, upstream stimulatory factor (USF), has been shown to bind invitro to a mutationally sensitive E-box motif within the 5′-flanking region of the Pdx-1 gene [Sharma, Leonard, Lee, Chapman, Leiter and Montminy (1996) J. Biol. Chem. 271, 2294-2299]. In the present study, we show that USF not only binds to the Pdx-1 gene promoter but also functionally regulates the expression of the Pdx-1 gene in differentiated pancreatic β-cells. Adenovirus-mediated overexpression of a dominant negative form of USF2 decreased binding of endogenous USF to the E-box element by ~ 90%. This reduction in endogenous USF binding led to a greater than 50% decrease in Pdx-1 gene promoter activity, which, in turn, resulted in marked reductions in Pdx-1 mRNA and protein levels. Importantly, the lower Pdx-1 protein levels led to a greater than 50% reduction in Pdx-1 binding activity to the A3 element on the insulin gene promoter, and a significant reduction in insulin mRNA levels. Overall, our results show that USF functionally regulates Pdx-1 gene expression in differentiated pancreatic β-cells and provide the first functional data for a role of USF in the regulation of a normal cellular gene.

scholarly journals Activating Hippo Pathway via Rassf1 by Ursolic Acid Suppresses the Tumorigenesis of Gastric Cancer

2019 ◽  
Vol 20 (19) ◽  
pp. 4709 ◽  
Author(s):  
Seong-Hun Kim ◽  
Hua Jin ◽  
Ruo Yu Meng ◽  
Da-Yeah Kim ◽  
Yu Chuan Liu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gastric Cancer ◽  
Cancer Cells ◽  
Ursolic Acid ◽  
Hippo Pathway ◽  
Dependent Manner ◽  
Gastric Cancer Cells ◽  
Protein Levels ◽  
Tumor Tissues ◽  
The Hippo Pathway

The Hippo pathway is often dysregulated in many carcinomas, which results in various stages of tumor progression. Ursolic acid (UA), a natural compound that exists in many herbal plants, is known to obstruct cancer progression and exerts anti-carcinogenic effect on a number of human cancers. In this study, we aimed to examine the biological mechanisms of action of UA through the Hippo pathway in gastric cancer cells. MTT assay showed a decreased viability of gastric cancer cells after treatment with UA. Following treatment with UA, colony numbers and the sizes of gastric cancer cells were significantly diminished and apoptosis was observed in SNU484 and SNU638 cells. The invasion and migration rates of gastric cancer cells were suppressed by UA in a dose-dependent manner. To further determine the gene expression patterns that are related to the effects of UA, a microarray analysis was performed. Gene ontology analysis revealed that several genes, such as the Hippo pathway upstream target gene, ras association domain family (RASSF1), and its downstream target genes (MST1, MST2, and LATS1) were significantly upregulated by UA, while the expression of YAP1 gene, together with oncogenes (FOXM1, KRAS, and BATF), were significantly decreased. Similar to the gene expression profiling results, the protein levels of RASSF1, MST1, MST2, LATS1, and p-YAP were increased, whereas those of CTGF were decreased by UA in gastric cancer cells. The p-YAP expression induced in gastric cancer cells by UA was reversed with RASSF1 silencing. In addition, the protein levels in the Hippo pathway were increased in the UA-treated xenograft tumor tissues as compared with that in the control tumor tissues; thus, UA significantly inhibited the tumorigenesis of gastric cancer in vivo in xenograft animals. Collectively, UA diminishes the proliferation and metastasis of gastric cancer via the regulation of Hippo pathway through Rassf1, which suggests that UA can be used as a potential chemopreventive and therapeutic agent for gastric cancer.

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 Upstream stimulatory factor-2 mediates quercetin-induced suppression of PAI-1 gene expression in human endothelial cells

2010 ◽  
Vol 111 (3) ◽  
pp. 720-726 ◽  
Author(s):  
Nélida C. Olave ◽  
Maximiliano H. Grenett ◽  
Martin Cadeiras ◽  
Hernan E. Grenett ◽  
Paul J. Higgins
Keyword(s):  
Gene Expression ◽  
Endothelial Cells ◽  
Upstream Stimulatory Factor ◽  
Human Endothelial Cells ◽  
Stimulatory Factor ◽  
Pai 1

Tumor necrosis factor inhibits growth hormone-mediated gene expression in hepatocytes

2006 ◽  
Vol 291 (1) ◽  
pp. G35-G44 ◽  
Author(s):  
Tamer Ahmed ◽  
Gladys Yumet ◽  
Margaret Shumate ◽  
Charles H. Lang ◽  
Peter Rotwein ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Mrna Expression ◽  
Gene Transcription ◽  
Protein Tyrosine Phosphatases ◽  
Mrna Levels ◽  
Inhibitory Effects ◽  
Protein Levels ◽  
Mrna Induction ◽  
Igf I

Growth hormone (GH) stimulates STAT5 phosphorylation by JAK2, which activates IGF-I and serine protease inhibitor 2.1 (Spi 2.1) transcription, whereas STAT5 dephosphorylation by protein tyrosine phosphatases (PTPs) terminates this signal. We hypothesized that the inhibitory effects of TNF on GH signaling and gene transcription were responsible for hepatic GH resistance. CWSV-1 hepatocytes were treated with TNF, pervanadate (a PTP inhibitor), or both, before GH stimulation. Total and tyrosine-phosphorylated JAK2, STAT5, ERK1/2, SHP-1 and SHP-2, IGF-I, and Spi 2.1 mRNA levels were measured. GH stimulated STAT5 and ERK1/2 phosphorylation, IGF-I, and Spi 2.1 mRNA expression. TNF attenuated JAK2/STAT5 and ERK1/2 phosphorylation and IGF-I and Spi 2.1 mRNA expression following GH stimulation. SHP-1 and SHP-2 protein levels were unaltered by TNF or GH, and the GH-induced increase in SHP-1 PTP activity was not further increased by TNF. In TNF-treated cells, pervanadate restored STAT5 and ERK1/2 phosphorylation to control levels following GH stimulation but did not restore IGF-I or Spi 2.1 mRNA induction. Cells transfected with a Spi 2.1 promoter-luciferase vector demonstrate a 50-fold induction in luciferase activity following GH stimulation or cotransfection with a constitutively active STAT5 vector. TNF prevented the induction of Spi 2.1 promoter activity by GH and the STAT5 construct. We conclude that TNF does not inhibit GH activity by inducing SHP-1 or -2 expression and that correction of GH signaling defects in TNF-treated cells by pervanadate does not restore GH-induced gene expression. The inhibitory effects of TNF on GH-mediated gene transcription appear independent of STAT5 activity and previously identified abnormalities in JAK2/STAT5 signaling.

Abstract 252: Dysregulation of β-Adrenergic Signaling in Hearts with Hyperinsulinemia

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Qin Fu ◽  
Evan Abel ◽  
Y Kevin Xiang
Keyword(s):  
Heart Failure ◽  
Heart Disease ◽  
Left Ventricular ◽  
Camp Signaling ◽  
Diabetic Patients ◽  
Dependent Manner ◽  
Insulin Stimulation ◽  
Protein Levels ◽  
Phosphodiesterase 4 ◽  
Phosphodiesterase 4D

Introduction: Epidemiological studies have demonstrated an increased risk of heart failure in diabetics, but the mechanisms linking diabetes mellitus (DM) to heart failure remain unclear. A uniform metabolic disturbance that characterizes type 2 diabetes is hyperinsulinemia, which accelerates adverse left ventricular (LV) remodeling in pressure overload hypertrophy. Hypothesis: We hypothesize that hyperinsulinemia might affect LV contractility by directly impairing β-adrenergic receptor (βAR) signaling. Methods and Results: Insulin receptor and β 2 AR form a cell surface complex, which dissociates upon insulin stimulation in the heart and cardiomyocytes. Insulin dose-dependent significantly inhibits PKA activities induced by a βAR agonist isoproterenol, and subsequently impairs isoproterenol-induced PKA phosphorylation of phospholamban and contractile responses in myocytes. Mechanistically, insulin action is mediated via IR and β 2 AR dependent manner. Insulin induces both PKA and GRK2-mediated phosphorylation of the β 2 AR, leading to enhanced β 2 AR/Gi coupling that inhibits adenylyl cyclase-mediated cAMP production. Pretreatment with Gi inhibitor pertussis toxin abolishes the insulin-mediated impairment of β-adrenergic stimulation of cAMP signaling. Further studies reveal that chronic insulin stimulation increases phosphodiesterase 4D protein levels in cardiac myocytes, and that the expression of phosphodiesterase 4D is also increased in animal models with high fat feeding or after 2-weeks of transaortic constriction. This leads further attenuation of βAR-induced cAMP activity for contraction response. Inhibition of phosphodiesterase 4 with rolipram rescues cAMP signaling induced by isoproterenol after insulin treatment. Last, PDE4D protein levels are significantly induced in the myocardium in diabetic patients with heart disease compared to those non-diabetic patients with heart disease. Conclusions: This is the first evidence showing that hyperinsulinemia might adversely impact cardiac contractility by inhibiting βAR signaling, which is due to IR-induced β 2 AR/Gi coupling and phosphodiesterase 4 expression in the βAR signaling cascades.

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