scholarly journals The Krüppel-Like Protein Gli-Similar 3 (Glis3) Functions as a Key Regulator of Insulin Transcription

2013 ◽  
Vol 27 (10) ◽  
pp. 1692-1705 ◽  
Author(s):  
Gary T. ZeRuth ◽  
Yukimasa Takeda ◽  
Anton M. Jetten
Keyword(s):  
Transcriptional Regulation ◽  
Regulatory Region ◽  
Neonatal Diabetes ◽  
Creb Binding Protein ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Synergistic Activation ◽  
Transcriptional Regulatory ◽  
Insulin Promoter ◽  
Regulatory Complex

Transcriptional regulation of insulin in pancreatic β-cells is mediated primarily through enhancer elements located within the 5′ upstream regulatory region of the preproinsulin gene. Recently, the Krüppel-like transcription factor, Gli-similar 3 (Glis3), was shown to bind the insulin (INS) promoter and positively influence insulin transcription. In this report, we examined in detail the synergistic activation of insulin transcription by Glis3 with coregulators, CREB-binding protein (CBP)/p300, pancreatic and duodenal homeobox 1 (Pdx1), neuronal differentiation 1 (NeuroD1), and v-maf musculoaponeurotic fibrosarcoma oncogene homolog A (MafA). Our data show that Glis3 expression, the binding of Glis3 to GlisBS, and its recruitment of CBP are required for optimal activation of the insulin promoter in pancreatic β-cells not only by Glis3, but also by Pdx1, MafA, and NeuroD1. Mutations in the GlisBS or small interfering RNA−directed knockdown of GLIS3 diminished insulin promoter activation by Pdx1, NeuroD1, and MafA, and neither Pdx1 nor MafA was able to stably associate with the insulin promoter when the GlisBS were mutated. In addition, a GlisBS mutation in the INS promoter implicated in the development of neonatal diabetes similarly abated activation by Pdx1, NeuroD1, and MafA that could be reversed by increased expression of exogenous Glis3. We therefore propose that recruitment of CBP/p300 by Glis3 provides a scaffold for the formation of a larger transcriptional regulatory complex that stabilizes the binding of Pdx1, NeuroD1, and MafA complexes to their respective binding sites within the insulin promoter. Taken together, these results indicate that Glis3 plays a pivotal role in the transcriptional regulation of insulin and may serve as an important therapeutic target for the treatment of diabetes.

scholarly journals Diabetes induced by gain-of-function mutations in the Kir6.1 subunit of the KATP channel

2016 ◽  
Vol 149 (1) ◽  
pp. 75-84 ◽  
Author(s):  
Maria S. Remedi ◽  
Jonathan B. Friedman ◽  
Colin G. Nichols
Keyword(s):  
Insulin Secretion ◽  
Katp Channel ◽  
Vascular System ◽  
Wild Type Mouse ◽  
Neonatal Diabetes ◽  
Katp Channels ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Gain Of Function ◽  
Insulin Promoter

Gain-of-function (GOF) mutations in the pore-forming (Kir6.2) and regulatory (SUR1) subunits of KATP channels have been identified as the most common cause of human neonatal diabetes mellitus. The critical effect of these mutations is confirmed in mice expressing Kir6.2-GOF mutations in pancreatic β cells. A second KATP channel pore-forming subunit, Kir6.1, was originally cloned from the pancreas. Although the prominence of this subunit in the vascular system is well documented, a potential role in pancreatic β cells has not been considered. Here, we show that mice expressing Kir6.1-GOF mutations (Kir6.1[G343D] or Kir6.1[G343D,Q53R]) in pancreatic β cells (under rat-insulin-promoter [Rip] control) develop glucose intolerance and diabetes caused by reduced insulin secretion. We also generated transgenic mice in which a bacterial artificial chromosome (BAC) containing Kir6.1[G343D] is incorporated such that the transgene is only expressed in tissues where Kir6.1 is normally present. Strikingly, BAC-Kir6.1[G343D] mice also show impaired glucose tolerance, as well as reduced glucose- and sulfonylurea-dependent insulin secretion. However, the response to K+ depolarization is intact in Kir6.1-GOF mice compared with control islets. The presence of native Kir6.1 transcripts was demonstrated in both human and wild-type mouse islets using quantitative real-time PCR. Together, these results implicate the incorporation of native Kir6.1 subunits into pancreatic KATP channels and a contributory role for these subunits in the control of insulin secretion.

scholarly journals Regulation of Insulin Gene Transcription by the Immediate-Early Growth Response Gene Egr-1

Endocrinology ◽  
2006 ◽  
Vol 147 (6) ◽  
pp. 2923-2935 ◽  
Author(s):  
Kazuhiro Eto ◽  
Varinderpal Kaur ◽  
Melissa K. Thomas
Keyword(s):  
Transcriptional Activation ◽  
Growth Response ◽  
Insulin Gene ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Expression Levels ◽  
Promoter Sequences ◽  
Early Growth Response ◽  
Insulin Promoter ◽  
Insulin Gene Expression

Abstract Changes in extracellular glucose levels regulate the expression of the immediate-early response gene and zinc finger transcription factor early growth response-1 (Egr-1) in insulin-producing pancreatic β-cells, but key target genes of Egr-1 in the endocrine pancreas have not been identified. We found that overexpression of Egr-1 in clonal (INS-1) β-cells increased transcriptional activation of the rat insulin I promoter. In contrast, reductions in Egr-1 expression levels or function with the introduction of either small interfering RNA targeted to Egr-1 (siEgr-1) or a dominant-negative form of Egr-1 decreased insulin promoter activation, and siEgr-1 suppressed insulin gene expression. Egr-1 did not directly interact with insulin promoter sequences, and mutagenesis of a potential G box recognition sequence for Egr-1 did not impair the Egr-1 responsiveness of the insulin promoter, suggesting that regulation of insulin gene expression by Egr-1 is probably mediated through additional transcription factors. Overexpression of Egr-1 increased, and reduction of Egr-1 expression decreased, transcriptional activation of the glucose-responsive FarFlat minienhancer within the rat insulin I promoter despite the absence of demonstrable Egr-1-binding activity to FarFlat sequences. Notably, augmenting Egr-1 expression levels in insulin-producing cells increased the mRNA and protein expression levels of pancreas duodenum homeobox-1 (PDX-1), a major transcriptional regulator of glucose-responsive activation of the insulin gene. Increasing Egr-1 expression levels enhanced PDX-1 binding to insulin promoter sequences, whereas mutagenesis of PDX-1-binding sites reduced the capacity of Egr-1 to activate the insulin promoter. We propose that changes in Egr-1 expression levels in response to extracellular signals, including glucose, can regulate PDX-1 expression and insulin production in pancreatic β-cells.

scholarly journals Conditional Deletion of Men1 in the Pancreatic β-Cell Leads to Glucagon-Expressing Tumor Development

Endocrinology ◽  
2015 ◽  
Vol 156 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Feng Li ◽  
Yutong Su ◽  
Yulong Cheng ◽  
Xiuli Jiang ◽  
Ying Peng ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Tumor Development ◽  
Β Cells ◽  
Β Cell ◽  
Pancreatic Β Cells ◽  
Pou Domain ◽  
Conditional Deletion ◽  
Cell Specificity ◽  
Insulin Promoter ◽  
Family Protein

Abstract The tumor suppressor menin is recognized as a key regulator of β-cell proliferation. To induce tumorigenesis within the pancreatic β-cells, floxed alleles of Men1 were selectively ablated using Cre-recombinase driven by the insulin promoter. Despite the β-cell specificity of the RipCre, glucagon-expressing tumors as well as insulinomas developed in old mutant mice. These glucagon-expressing tumor cells were menin deficient and expressed the mature α-cell-specific transcription factors Brain-specific homeobox POU domain protein 4 (Brn4) and v-maf musculoaponeurotic fibrosarcoma oncogene family, protein B (MafB). Moreover, the inactivation of β-cell-specific transcription factors was observed in mutant β-cells. Our work shows that Men1 ablation in the pancreatic β-cells leads to the inactivation of specific transcription factors, resulting in glucagon-expressing tumor development, which sheds light on the mechanisms of islet tumorigenesis.

scholarly journals Specific transgene expression in mouse pancreatic β-cells under the control of the porcine insulin promoter

2010 ◽  
Vol 315 (1-2) ◽  
pp. 219-224 ◽  
Author(s):  
Marjeta Grzech ◽  
Maik Dahlhoff ◽  
Nadja Herbach ◽  
Felix A. Habermann ◽  
Ingrid Renner-Müller ◽  
...  
Keyword(s):  
Transgene Expression ◽  
Porcine Insulin ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Insulin Promoter

Transcriptional regulation of the IAPP gene in pancreatic β-cells

2004 ◽  
Vol 1681 (1) ◽  
pp. 28-37 ◽  
Author(s):  
Louisa M.A. Shepherd ◽  
Susan C. Campbell ◽  
Wendy M. Macfarlane
Keyword(s):  
Transcriptional Regulation ◽  
Β Cells ◽  
Pancreatic Β Cells

scholarly journals Transcriptional Regulation of Glucose Sensors in Pancreatic β-Cells and Liver: An Update

Sensors ◽  
2010 ◽  
Vol 10 (5) ◽  
pp. 5031-5053 ◽  
Author(s):  
Jin-Sik Bae ◽  
Tae-Hyun Kim ◽  
Mi-Young Kim ◽  
Joo-Man Park ◽  
Yong-Ho Ahn
Keyword(s):  
Transcriptional Regulation ◽  
Glucose Sensors ◽  
Β Cells ◽  
Pancreatic Β Cells

scholarly journals Hedgehog Signaling Regulation of Homeodomain Protein Islet Duodenum Homeobox-1 Expression in Pancreatic β-Cells*

Endocrinology ◽  
2001 ◽  
Vol 142 (3) ◽  
pp. 1033-1040 ◽  
Author(s):  
Melissa K. Thomas ◽  
Jee H. Lee ◽  
Naina Rastalsky ◽  
Joel F. Habener
Keyword(s):  
Gene Expression ◽  
Transcriptional Activation ◽  
Gene Promoter ◽  
Insulin Gene ◽  
Reporter Construct ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Insulin Promoter ◽  
Insulin Gene Expression ◽  
Hh Signaling

Abstract Insulin gene expression in pancreatic β-cells is regulated by signals from developmental morphogen proteins known as hedgehogs (Hhs). By analyzing 5′-deletion insulin promoter-reporter constructs in transient transfections of clonal INS-1 β-cells, we located activating Hh-responsive regions within the rat insulin I promoter that include the glucose-response elements Far (E2) and Flat (A2/A3). Activation of Hh signaling in INS-1 cells by ectopic Hh expression increased (and inhibition of Hh signaling with the Hh-specific inhibitor cyclopamine decreased) transcriptional activation of a multimerized FarFlat enhancer-reporter construct. In DNA-binding studies, nuclear extracts from INS-1 cells activated by ectopic Hh expression increased (and extracts from INS-1 cells treated with cyclopamine decreased) protein binding to a radiolabeled FarFlat oligonucleotide probe. An antiserum directed against the transcription factor islet duodenum homeobox-1 (IDX-1), a regulator of pancreas development and activator of the insulin gene promoter, attenuated the binding activity of Hh-responsive protein complexes. Nuclear IDX-1 protein levels on Western blots were increased by ectopic Hh expression, thereby providing a mechanism for Hh-mediated regulation of the insulin promoter. Addition of cyclopamine to INS-1 cells decreased IDX-1 messenger RNA expression. In transient transfections of a− 4.5-kb mouse IDX-1 promoter-reporter construct, ectopic Hh expression increased (and cyclopamine administration decreased) transcriptional activation of the IDX-1 promoter in a dose-dependent manner. Thus, the IDX-1 gene is a direct regulatory target of Hh signaling in insulin-producing pancreatic β-cells. We propose that Hh signaling activates the insulin gene promoter indirectly via the direct activation of IDX-1 expression. Because IDX-1 gene expression is essential for insulin gene expression, pancreatic β-cell development, and normal glucose homeostasis, our findings that Hh signaling regulates IDX-1 expression in the endocrine pancreas suggest possible novel therapeutic approaches for diabetes mellitus.

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.

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