scholarly journals Human Krüppel-like factor 11 differentially regulates human insulin promoter activity in β-cells and non-β-cells via p300 and PDX1 through the regulatory sites A3 and CACCC box

2012 ◽  
Vol 363 (1-2) ◽  
pp. 20-26 ◽  
Author(s):  
Nikolaos Perakakis ◽  
Despoina Danassi ◽  
Marcus Alt ◽  
Eleni Tsaroucha ◽  
Amir E. Mehana ◽  
...  
Keyword(s):  
Human Insulin ◽  
Promoter Activity ◽  
Β Cells ◽  
Insulin Promoter ◽  
Regulatory Sites

scholarly journals Glucose enhances insulin promoter activity in MIN6 β-cells independently of changes in intracellular Ca2+ concentration and insulin secretion

1999 ◽  
Vol 342 (2) ◽  
pp. 275-280 ◽  
Author(s):  
Helen J. KENNEDY ◽  
Imran RAFIQ ◽  
Aristea E. POULI ◽  
Guy A. RUTTER
Keyword(s):  
Promoter Activity ◽  
Photon Counting ◽  
Firefly Luciferase ◽  
Receptor Activation ◽  
Luciferase Reporter ◽  
Β Cells ◽  
Viral Promoter ◽  
Luciferase Reporter Construct ◽  
Insulin Promoter ◽  
Firefly Luciferase Reporter

Recent studies have suggested that glucose may activate insulin gene transcription through increases in intracellular Ca2+ concentration, possibly acting via the release of stored insulin. We have investigated this question by dynamic photon-counting imaging of insulin- and c-fos-promoter-firefly luciferase reporter construct activity. Normalized to constitutive viral promoter activity, insulin promoter activity in MIN6 β-cells was increased 1.6-fold after incubation at 30 mM compared with 3 mM glucose, but was unaltered at either glucose concentration by the presence of insulin (100 nM) or the Ca2+ channel inhibitor, verapamil (100 μM). Increases in intracellular [Ca2+] achieved by plasma membrane depolarization with KCl failed to enhance either insulin or c-fos promoter activity in MIN6 cells, but increased c-fos promoter activity 5-fold in AtT20 cells. Together, these results demonstrate that glucose can exert a direct effect on insulin promoter activity in islet β-cells, via a signalling pathway which does not require increases in intracellular [Ca2+] nor insulin release and insulin receptor activation.

scholarly journals Phenothiazine Neuroleptics Signal to the Human Insulin Promoter as Revealed by a Novel High-Throughput Screen

2010 ◽  
Vol 15 (6) ◽  
pp. 663-670 ◽  
Author(s):  
Alice Kiselyuk ◽  
Suzette Farber-Katz ◽  
Tom Cohen ◽  
Seung-Hee Lee ◽  
Ifat Geron ◽  
...  
Keyword(s):  
Cell Line ◽  
Human Insulin ◽  
High Throughput ◽  
High Throughput Screening ◽  
Promoter Activity ◽  
Central Element ◽  
Bhlh Transcription Factor ◽  
Β Cell ◽  
Insulin Promoter ◽  
Short Term Exposure

A number of diabetogenic stimuli interact to influence insulin promoter activity, making it an attractive target for both mechanistic studies and therapeutic interventions. High-throughput screening (HTS) for insulin promoter modulators has the potential to reveal novel inputs into the control of that central element of the pancreatic β-cell. A cell line from human islets in which the expression of insulin and other β-cell-restricted genes are modulated by an inducible form of the bHLH transcription factor E47 was developed. This cell line, T6PNE, was adapted for HTS by transduction with a vector expressing green fluorescent protein under the control of the human insulin promoter. The resulting cell line was screened against a library of known drugs for those that increase insulin promoter activity. Members of the phenothiazine class of neuroleptics increased insulin gene expression upon short-term exposure. Chronic treatment, however, resulted in suppression of insulin promoter activity, consistent with the effect of phenothiazines observed clinically to induce diabetes in chronically treated patients. In addition to providing insights into previously unrecognized targets and mechanisms of action of phenothiazines, the novel cell line described here provides a broadly applicable platform for mining new molecular drug targets and central regulators of β-cell differentiated function.

DREAM regulates insulin promoter activity through newly identified DRE element

2013 ◽  
Vol 8 (2) ◽  
pp. 97-106
Author(s):  
Teodora Daneva ◽  
Shina Pashova ◽  
Radoslava Emilova ◽  
Plamen Padeshki ◽  
Hristo Gagov ◽  
...  
Keyword(s):  
Islets Of Langerhans ◽  
Gene Transcription ◽  
Promoter Activity ◽  
Regulatory Element ◽  
Transcriptional Start Site ◽  
Gene Promoter ◽  
Insulin Gene ◽  
Β Cells ◽  
Insulin Promoter ◽  
Direct Binding

AbstractDownstream regulatory element antagonist modulator (DREAM) protein is a 31 kDa Ca2+-regulated transcriptional repressor. It functions as a silencer of the gene transcription. In low intracellular free Ca2+ concentration DREAM tightly binds to the downstream regulatory element (DRE) of gene promoter and impedes the transcription. In higher Ca2+ concentrations DREAM binds Ca2+ and disconnects from DRE of the gene promoter enabling transcription. We report that DREAM is expressed in different human tissues including the pancreas, where it is located in the islets of Langerhans. Location of DREAM in RIN-F5 cells in cultures is restricted to the nucleus and membranes and changes after increased Ca2+-levels. The proteins dissociate from dimmers to monomers and translocate out of the nucleus. The expression of DREAM in β-cells in the islets of Langerhans regulates the promoter activity of the insulin gene by directly interacting with the sequence located between +52 bp and +81 bp downstream of the transcriptional start site of the promoter. Our results provide evidence for the existence of DRE sequence in the insulin gene promoter. It is suggested that DREAM is a repressor of insulin gene transcription, whose effect is mediated by direct binding to DRE sequence.

scholarly journals c-Jun represses the human insulin promoter activity that depends on multiple cAMP response elements.

1992 ◽  
Vol 89 (3) ◽  
pp. 1045-1049 ◽  
Author(s):  
N. Inagaki ◽  
T. Maekawa ◽  
T. Sudo ◽  
S. Ishii ◽  
Y. Seino ◽  
...  
Keyword(s):  
Human Insulin ◽  
Promoter Activity ◽  
Response Elements ◽  
Insulin Promoter

scholarly journals Relative contribution of PDX-1, MafA and E47/β2 to the regulation of the human insulin promoter

2005 ◽  
Vol 389 (3) ◽  
pp. 813-820 ◽  
Author(s):  
Hilary M. Docherty ◽  
Colin W. Hay ◽  
Laura A. Ferguson ◽  
John Barrow ◽  
Elaine Durward ◽  
...  
Keyword(s):  
Human Insulin ◽  
Promoter Activity ◽  
Leucine Zipper ◽  
Synergistic Effects ◽  
Regulatory Elements ◽  
Basic Leucine Zipper ◽  
Helix Loop Helix ◽  
Relative Contribution ◽  
Endogenous Insulin ◽  
Insulin Promoter

The insulin promoter binds a number of tissue-specific and ubiquitous transcription factors. Of these, the homoeodomain protein PDX-1 (pancreatic duodenal homeobox factor-1), the basic leucine zipper protein MafA and the basic helix–loop–helix heterodimer E47/BETA2 (β-cell E box transactivator 2; referred to here as β2) bind to important regulatory sites. Previous studies have shown that PDX-1 can interact synergistically with E47 and β2 to activate the rat insulin 1 promoter. The aim of the present study was to determine the relative contribution of PDX-1, MafA and E47/β2 in regulating the human insulin promoter, and whether these factors could interact synergistically in the context of the human promoter. Mutagenesis of the PDX-1, MafA and E47/β2 binding sites reduced promoter activity by 60, 74 and 94% respectively, in INS-1 β-cells. In the islet glucagonoma cell line αTC1.6, overexpression of PDX-1 and MafA separately increased promoter activity approx. 2.5–3-fold, and in combination approx. 6-fold, indicating that their overall effect was additive. Overexpression of E47 and β2 had no effect. In HeLa cells, PDX-1 stimulated the basal promoter by approx. 40-fold, whereas MafA, E47 and β2 each increased activity by less than 2-fold. There was no indication of any synergistic effects on the human insulin promoter. On the other hand, the rat insulin 1 promoter and a mutated version of the human insulin promoter, in which the relevant regulatory elements were separated by the same distances as in the rat insulin 1 promoter, did exhibit synergy. PDX-1 was shown further to activate the endogenous insulin 1 gene in αTC1.6 cells, whereas MafA activated the insulin 2 gene. In combination, PDX-1 and MafA activated both insulin genes. Chromatin immunoprecipitation assays confirmed that PDX-1 increased the association of acetylated histones H3 and H4 with the insulin 1 gene and MafA increased the association of acetylated histone H3 with the insulin 2 gene.

scholarly journals Elevated Glucose Attenuates Human Insulin Gene Promoter Activity in INS-1 Pancreatic β-Cells via Reduced Nuclear Factor Binding to the A5/Core and Z Element

2005 ◽  
Vol 19 (5) ◽  
pp. 1343-1360 ◽  
Author(s):  
Maria F. Pino ◽  
Diana Z. Ye ◽  
Katrina D. Linning ◽  
Christopher D. Green ◽  
Barton Wicksteed ◽  
...  
Keyword(s):  
Human Insulin ◽  
Promoter Activity ◽  
Gene Promoter ◽  
Insulin Gene ◽  
Nuclear Factor ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Factor Binding ◽  
Human Insulin Gene ◽  
Elevated Glucose

Analysis of human insulin promoter activity in primary human endocrine pancreatic beta-cells

2004 ◽  
Vol 112 (S 1) ◽  
Author(s):  
S Hohloch ◽  
S Hügl ◽  
G Päth ◽  
S Rummel ◽  
M Brendel ◽  
...  
Keyword(s):  
Beta Cells ◽  
Human Insulin ◽  
Pancreatic Beta Cells ◽  
Promoter Activity ◽  
Insulin Promoter

scholarly journals Glucagon-like peptide-1 stimulates human insulin promoter activity in part through cAMP-responsive elements that lie upstream and downstream of the transcription start site

2005 ◽  
Vol 186 (2) ◽  
pp. 353-365 ◽  
Author(s):  
Colin W Hay ◽  
Elaine M Sinclair ◽  
Giovanna Bermano ◽  
Elaine Durward ◽  
Mohammad Tadayyon ◽  
...  
Keyword(s):  
Protein Binding ◽  
Human Insulin ◽  
Insulin Gene ◽  
Start Site ◽  
Β Cells ◽  
Transcription Start ◽  
Pancreatic Β Cells ◽  
Insulin Promoter ◽  
Glucagon Like Peptide ◽  
Glucagon Like Peptide 1

Glucagon-like peptide-1 (GLP-1) is a peptide hormone secreted from the enteroendocrine L-cells of the gut and which acts primarily to potentiate the effects of glucose on insulin secretion from pancreatic β-cells. It also stimulates insulin gene expression, proinsulin biosynthesis and affects the growth and differentiation of the islets of Langerhans. Previous studies on the mechanisms whereby GLP-1 regulates insulin gene transcription have focused on the rat insulin promoter. The aim of this study was to determine whether the human insulin promoter was also responsive to GLP-1, and if so to investigate the possible role of cAMP-responsive elements (CREs) that lie upstream (CRE1 and CRE2) and downstream (CRE3 and CRE4) of the transcription start site. INS-1 pancreatic β-cells were transfected with promoter constructs containing fragments of the insulin gene promoter placed upstream of the firefly luciferase reporter gene. GLP-1 was found to stimulate the human insulin promoter, albeit to a lesser degree than the rat insulin promoter. Mutagenesis of CRE2, CRE3 and CRE4 blocked the stimulatory effect of GLP-1 while mutagenesis of CRE1 had no effect. Analysis of nuclear protein binding to the four CREs showed that, while they share some proteins, each CRE site is unique. Stimulation of transcription by GLP-1 through CRE2, CRE3 and CRE4 resulted in altered protein binding that was different for each of the CRE sites involved. Collectively, these data show that the four human CREs are not simply multiple copies of the rat CRE site and further emphasise that the human insulin promoter is distinct from the rodent promoter.

scholarly journals Insulin stimulates pancreatic–duodenal homoeobox factor-1 (PDX1) DNA-binding activity and insulin promoter activity in pancreatic β cells

1999 ◽  
Vol 344 (3) ◽  
pp. 813-818 ◽  
Author(s):  
Hong WU ◽  
Wendy M. MACFARLANE ◽  
Mohammad TADAYYON ◽  
Jonathan R. S. ARCH ◽  
Roger F. L. JAMES ◽  
...  
Keyword(s):  
Dna Binding ◽  
Promoter Activity ◽  
Kinase Inhibitors ◽  
Binding Activity ◽  
Phosphatidylinositol 3 Kinase ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Dna Binding Activity ◽  
Insulin Promoter

Pancreatic-duodenal homoeobox factor-1 (PDX1) is a homoeodomain transcription factor that plays an important role in linking glucose metabolism in pancreatic β cells to the regulation of insulin gene transcription. Our previous results indicated that glucose activates PDX1 DNA-binding activity and insulin promoter activity via a stress-activated signalling pathway involving phosphatidylinositol 3-kinase (PtdIns 3-kinase) and stress-activated protein kinase 2 (SAPK2/p38). The present study was undertaken to determine the effects of other metabolizable and non-metabolizable nutrients. The results indicate that non-metabolizable nutrients, with the exception of 2-deoxyglucose, had no effect. Metabolizable nutrients that could stimulate calcium uptake and insulin release were shown to activate both PDX1 and the insulin promoter. The possible role of insulin acting via an autoregulatory loop was therefore examined. Insulin was shown to potently activate PDX1 DNA-binding activity and insulin promoter activity. The effects of insulin were inhibited by the PtdIns 3-kinase inhibitors wortmannin and LY294002 and by the SAPK2 inhibitor SB203580, suggesting that its effects were mediated via activation of PtdIns 3-kinase and SAPK2. Further support for the insulin-mediated activation of SAPK2 came from the observation that both glucose and insulin stimulated the phosphorylation of SAPK2. These results suggest that both glucose and insulin stimulate PDX1 DNA-binding activity and insulin promoter activity via a pathway involving PtdIns 3-kinase and SAPK2.

scholarly journals Insulin stimulates pancreatic‒duodenal homoeobox factor-1 (PDX1) DNA-binding activity and insulin promoter activity in pancreatic β cells

1999 ◽  
Vol 344 (3) ◽  
pp. 813 ◽  
Author(s):  
Hong WU ◽  
Wendy M. MACFARLANE ◽  
Mohammad TADAYYON ◽  
Jonathan R.S. ARCH ◽  
Roger F.L. JAMES ◽  
...  
Keyword(s):  
Dna Binding ◽  
Promoter Activity ◽  
Binding Activity ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Dna Binding Activity ◽  
Insulin Promoter
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