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Willmann SJ, Mueller NS, Engert S, Sterr M, Burtscher I, Raducanu A, Irmler M, Beckers J, Sass S, Theis FJ, Lickert H. The global gene expression profile of the secondary transition during pancreatic development. Mech Dev 2016; 139:51-64. [DOI: 10.1016/j.mod.2015.11.004] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 11/26/2015] [Accepted: 11/27/2015] [Indexed: 12/20/2022]
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2
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Abstract
Pancreatic β-cell dysfunction plays an important role in the pathogenesis of both type 1 and type 2 diabetes. Insulin, which is produced in β-cells, is a critical regulator of metabolism. Insulin is synthesized as preproinsulin and processed to proinsulin. Proinsulin is then converted to insulin and C-peptide and stored in secretary granules awaiting release on demand. Insulin synthesis is regulated at both the transcriptional and translational level. The cis-acting sequences within the 5' flanking region and trans-activators including paired box gene 6 (PAX6), pancreatic and duodenal homeobox- 1(PDX-1), MafA, and β-2/Neurogenic differentiation 1 (NeuroD1) regulate insulin transcription, while the stability of preproinsulin mRNA and its untranslated regions control protein translation. Insulin secretion involves a sequence of events in β-cells that lead to fusion of secretory granules with the plasma membrane. Insulin is secreted primarily in response to glucose, while other nutrients such as free fatty acids and amino acids can augment glucose-induced insulin secretion. In addition, various hormones, such as melatonin, estrogen, leptin, growth hormone, and glucagon like peptide-1 also regulate insulin secretion. Thus, the β-cell is a metabolic hub in the body, connecting nutrient metabolism and the endocrine system. Although an increase in intracellular [Ca2+] is the primary insulin secretary signal, cAMP signaling- dependent mechanisms are also critical in the regulation of insulin secretion. This article reviews current knowledge on how β-cells synthesize and secrete insulin. In addition, this review presents evidence that genetic and environmental factors can lead to hyperglycemia, dyslipidemia, inflammation, and autoimmunity, resulting in β-cell dysfunction, thereby triggering the pathogenesis of diabetes.
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Affiliation(s)
- Zhuo Fu
- Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA 24061, USA
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3
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Fu Z, Gilbert ER, Liu D. Regulation of insulin synthesis and secretion and pancreatic Beta-cell dysfunction in diabetes. Curr Diabetes Rev 2013; 9:25-53. [PMID: 22974359 PMCID: PMC3934755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2012] [Revised: 09/11/2012] [Accepted: 09/11/2012] [Indexed: 11/11/2023]
Abstract
Pancreatic β-cell dysfunction plays an important role in the pathogenesis of both type 1 and type 2 diabetes. Insulin, which is produced in β-cells, is a critical regulator of metabolism. Insulin is synthesized as preproinsulin and processed to proinsulin. Proinsulin is then converted to insulin and C-peptide and stored in secretary granules awaiting release on demand. Insulin synthesis is regulated at both the transcriptional and translational level. The cis-acting sequences within the 5' flanking region and trans-activators including paired box gene 6 (PAX6), pancreatic and duodenal homeobox- 1(PDX-1), MafA, and β-2/Neurogenic differentiation 1 (NeuroD1) regulate insulin transcription, while the stability of preproinsulin mRNA and its untranslated regions control protein translation. Insulin secretion involves a sequence of events in β-cells that lead to fusion of secretory granules with the plasma membrane. Insulin is secreted primarily in response to glucose, while other nutrients such as free fatty acids and amino acids can augment glucose-induced insulin secretion. In addition, various hormones, such as melatonin, estrogen, leptin, growth hormone, and glucagon like peptide-1 also regulate insulin secretion. Thus, the β-cell is a metabolic hub in the body, connecting nutrient metabolism and the endocrine system. Although an increase in intracellular [Ca2+] is the primary insulin secretary signal, cAMP signaling- dependent mechanisms are also critical in the regulation of insulin secretion. This article reviews current knowledge on how β-cells synthesize and secrete insulin. In addition, this review presents evidence that genetic and environmental factors can lead to hyperglycemia, dyslipidemia, inflammation, and autoimmunity, resulting in β-cell dysfunction, thereby triggering the pathogenesis of diabetes.
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Affiliation(s)
- Zhuo Fu
- Department of Human Nutrition, Foods and Exercise, Virginia Tech, Blacksburg, VA 24061, USA
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4
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Stein R. Insulin Gene Transcription: Factors Involved in Cell Type–Specific and Glucose‐Regulated Expression in Islet β Cells are Also Essential During Pancreatic Development. Compr Physiol 2011. [DOI: 10.1002/cphy.cp070202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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5
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Abstract
The biological responses of the transforming growth factor-β (TGF-β) superfamily, which includes Activins and Nodal, are induced by activation of a receptor complex and Smads. A type I receptor, which is a component of the complex, is known as an activin receptor-like kinase (ALK); currently seven ALKs (ALK1-ALK7) have been identified in humans. Activins signaling, which is mediated by ALK4 and 7 together with ActRIIA and IIB, plays a critical role in glucose-stimulated insulin secretion, development/neogenesis, and glucose homeostatic control of pancreatic endocrine cells; the insulin gene is regulated by these signaling pathways via ALK7, which is a receptor for Activins AB and B and Nodal. This review discusses signal transduction of ALKs in pancreatic endocrine cells and the role of ALKs in insulin gene regulation.
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Affiliation(s)
- Rie Watanabe
- Department of Diabetes and Clinical Nutrition, Kyoto University Graduate School of Medicine, Kyoto, Japan
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6
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Abstract
Production and secretion of insulin from the β-cells of the pancreas is very crucial in maintaining normoglycaemia. This is achieved by tight regulation of insulin synthesis and exocytosis from the β-cells in response to changes in blood glucose levels. The synthesis of insulin is regulated by blood glucose levels at the transcriptional and post-transcriptional levels. Although many transcription factors have been implicated in the regulation of insulin gene transcription, three β-cell-specific transcriptional regulators, Pdx-1 (pancreatic and duodenal homeobox-1), NeuroD1 (neurogenic differentiation 1) and MafA (V-maf musculoaponeurotic fibrosarcoma oncogene homologue A), have been demonstrated to play a crucial role in glucose induction of insulin gene transcription and pancreatic β-cell function. These three transcription factors activate insulin gene expression in a co-ordinated and synergistic manner in response to increasing glucose levels. It has been shown that changes in glucose concentrations modulate the function of these β-cell transcription factors at multiple levels. These include changes in expression levels, subcellular localization, DNA-binding activity, transactivation capability and interaction with other proteins. Furthermore, all three transcription factors are able to induce insulin gene expression when expressed in non-β-cells, including liver and intestinal cells. The present review summarizes the recent findings on how glucose modulates the function of the β-cell transcription factors Pdx-1, NeuroD1 and MafA, and thereby tightly regulates insulin synthesis in accordance with blood glucose levels.
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7
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Hrytsenko O, Wright JR, Pohajdak B. Regulation of insulin gene expression and insulin production in Nile tilapia (Oreochromis niloticus). Gen Comp Endocrinol 2008; 155:328-40. [PMID: 17618629 DOI: 10.1016/j.ygcen.2007.05.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/12/2007] [Revised: 04/25/2007] [Accepted: 05/07/2007] [Indexed: 10/23/2022]
Abstract
Compared to mammals, little is known about insulin gene expression in fish. Using transient transfection experiments and mammalian insulinoma cell lines we demonstrate that transcription of the Nile tilapia (Oreochromis niloticus) insulin gene is (a) regulated in a beta-cell-specific manner; and (b) not sensitive to the glucose stimulations. Deletion analysis of the 1575 bp 5' insulin gene flanking sequence revealed that cooperative interactions between regulatory elements within the proximal (-1 to -396 bp) and the distal (-396 bp to -1575 bp) promoter regions were necessary for induction of the beta-cell-specific transcription. Effects of glucose and arginine on endogenous insulin secretion, translation, and transcription in isolated tilapia Brockmann bodies were determined using Northern hybridization, Western analysis, and quantitative RT-PCR. Similar to the regulation of mammalian insulin, we found that increases of glucose (1-70 mM) and arginine (0.4-25 mM) induced insulin secretion. However, transcription of the insulin gene was activated only by extremely high concentrations of glucose and arginine added simultaneously. When stimulated for 24 h with low concentrations of both inducers or with either of them added separately, tilapia beta-cells were able to replenish secreted insulin and to maintain insulin stores at a constant level without elevations of the insulin mRNA levels. Since the basal level of insulin mRNA was approximately 3.7-fold higher in tilapia beta-cells than it is in mammalian beta-cells, insulin production in tilapia cells probably relies on an enlarged intracellular insulin mRNA pool and does not require the transcriptional activation of the insulin gene.
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Affiliation(s)
- Olga Hrytsenko
- Department of Biology, Dalhousie University, Halifax, NS, Canada B3H 4J1
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8
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Abderrahmani A, Niederhauser G, Favre D, Abdelli S, Ferdaoussi M, Yang JY, Regazzi R, Widmann C, Waeber G. Human high-density lipoprotein particles prevent activation of the JNK pathway induced by human oxidised low-density lipoprotein particles in pancreatic beta cells. Diabetologia 2007; 50:1304-14. [PMID: 17437081 DOI: 10.1007/s00125-007-0642-z] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 01/15/2007] [Indexed: 12/17/2022]
Abstract
AIMS/HYPOTHESIS We explored the potential adverse effects of pro-atherogenic oxidised LDL-cholesterol particles on beta cell function. MATERIALS AND METHODS Isolated human and rat islets and different insulin-secreting cell lines were incubated with human oxidised LDL with or without HDL particles. The insulin level was monitored by ELISA, real-time PCR and a rat insulin promoter construct linked to luciferase gene reporter. Cell apoptosis was determined by scoring cells displaying pycnotic nuclei. RESULTS Prolonged incubation with human oxidised LDL particles led to a reduction in preproinsulin expression levels, whereas the insulin level was preserved in the presence of native LDL-cholesterol. The loss of insulin production occurred at the transcriptional levels and was associated with an increase in activator protein-1 transcriptional activity. The rise in activator protein-1 activity resulted from activation of c-Jun N-terminal kinases (JNK, now known as mitogen-activated protein kinase 8 [MAPK8]) due to a subsequent decrease in islet-brain 1 (IB1; now known as MAPK8 interacting protein 1) levels. Consistent with the pro-apoptotic role of the JNK pathway, oxidised LDL also induced a twofold increase in the rate of beta cell apoptosis. Treatment of the cells with JNK inhibitor peptides or HDL countered the effects mediated by oxidised LDL. CONCLUSIONS/INTERPRETATION These data provide strong evidence that oxidised LDL particles exert deleterious effects in the progression of beta cell failure in diabetes and that these effects can be countered by HDL particles.
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Affiliation(s)
- A Abderrahmani
- Service of Internal Medicine, CHUV-Hospital, Rue du Bugnon 9, 1005 Lausanne, Switzerland.
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9
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Ohtsuka S, Murao K, Imachi H, Cao WM, Yu X, Li J, Iwama H, Wong NCW, Bancroft C, Ishida T. Prolactin regulatory element binding protein as a potential transcriptional factor for the insulin gene in response to glucose stimulation. Diabetologia 2006; 49:1599-607. [PMID: 16752178 DOI: 10.1007/s00125-006-0255-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2005] [Accepted: 02/13/2006] [Indexed: 11/29/2022]
Abstract
AIMS/HYPOTHESIS Prolactin regulatory element binding (PREB) protein has been identified as a factor that regulates prolactin promoter activity in rat anterior pituitary. PREB is located not only in the anterior pituitary but also in pancreas; however its role in the pancreas is not known. We therefore examined the role of PREB in insulin gene expression. MATERIALS AND METHODS To analyse the effects of PREB on insulin gene transcription, we employed the luciferase reporter gene assay and electrophoretic mobility shift assay (EMSA). In cells expressing or knocked down for PREB, insulin expression and secretion were determined. RESULTS PREB was located mainly in nuclei of rat pancreatic beta cells and its cell line, INS-1. A nuclear extract of INS-1 cells contained material that was recognised by PREB antiserum. This nuclear extract also showed insulin promoter binding activity that was super-shifted by PREB antiserum in EMSA studies. In the INS-1 cells, co-expression of PREB and the insulin promoter induced activity of the latter. The addition of glucose to the cells increased PREB expression. Deletional analysis of the insulin promoter showed that A3, a glucose-responsive cis-element in the insulin promoter, mediated the transcriptional effect of PREB. In addition, synthesised PREB bound the A3 element by EMSA, while a mutant of this motif in the insulin promoter abrogated the effect of PREB. Cells expressing or knocked down for PREB exhibited increased or decreased insulin expression, respectively. CONCLUSIONS/INTERPRETATION These results demonstrate that PREB may contribute to the regulation of insulin gene transcription and insulin secretion in response to glucose stimulation.
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Affiliation(s)
- S Ohtsuka
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Kagawa University, 1750-1, Miki-cho, Kita-gun, Kagawa, Japan
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10
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Smith SJ, Zhang H, Clermont AO, Powers AC, Kaufman DB, Purchio AF, West DB. In Vivo Monitoring of Pancreatic β-Cells in a Transgenic Mouse Model. Mol Imaging 2006. [DOI: 10.2310/7290.2006.00007] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
| | | | | | - Alvin C. Powers
- Vanderbilt University Medical Center
- VA Tennessee Valley Healthcare System
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11
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Oda H, Fushimi F, Kato M, Kitagawa M, Araki K, Seki N, Ohkubo H. Microarray analysis of the genes induced by tetracycline-regulated expression of NDRF/NeuroD2 in P19 cells. Biochem Biophys Res Commun 2005; 335:458-68. [PMID: 16083855 DOI: 10.1016/j.bbrc.2005.07.093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 07/15/2005] [Indexed: 11/17/2022]
Abstract
NeuroD-related factor (NDRF)/NeuroD2 is a basic helix-loop-helix (bHLH) protein that plays important roles in neuronal development. To elucidate the NDRF transcription network, we used mouse cDNA microarray analysis combined with a tetracycline-regulatable expression system in P19 embryonal carcinoma cells. Five genes were identified to be up-regulated in the presence of NDRF protein. RNA hybridization analysis confirmed that brain-lipid-binding protein (BLBP) and inhibitor of differentiation 1 (Id1) genes were among the five genes that were rapidly and significantly up-regulated after induction of NDRF. When a dominant negative form of NDRF protein was expressed during retinoic acid-induced neuronal differentiation of P19 cells, the BLBP gene, but not the Id1 gene, was potently repressed. Immunohistochemical analysis revealed that both NDRF and Id1 immunoreactivities were observed in some granule cells of the cerebellum in the postnatal period. These results suggest that NDRF or its related bHLH proteins may act upstream of these genes in a subset of developing neurons.
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Affiliation(s)
- Hisanobu Oda
- Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 862-0976, Japan.
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12
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Zhao L, Guo M, Matsuoka TA, Hagman DK, Parazzoli SD, Poitout V, Stein R. The islet beta cell-enriched MafA activator is a key regulator of insulin gene transcription. J Biol Chem 2005; 280:11887-94. [PMID: 15665000 DOI: 10.1074/jbc.m409475200] [Citation(s) in RCA: 141] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The islet-enriched MafA, PDX-1, and BETA2 activators contribute to both beta cell-specific and glucose-responsive insulin gene transcription. To investigate how these factors impart activation, their combined impact upon insulin enhancer-driven expression was first examined in non-beta cell line transfection assays. Individual expression of PDX-1 and BETA2 led to little or no activation, whereas MafA alone did so modestly. MafA together with PDX-1 or BETA2 produced synergistic activation, with even higher insulin promoter activity found when all three proteins were present. Stimulation was attenuated upon compromising either MafA transactivation or DNA-binding activity. MafA interacted with endogenous PDX-1 and BETA2 in coimmunoprecipitation and in vitro GST pull-down assays, suggesting that regulation involved direct binding. Dominant-negative acting and small interfering RNAs of MafA also profoundly reduced insulin promoter activity in beta cell lines. In addition, MafA was induced in parallel with insulin mRNA expression in glucose-stimulated rat islets. Insulin mRNA levels were also elevated in rat islets by adenoviral-mediated expression of MafA. Collectively, these results suggest that MafA plays a key role in coordinating and controlling the level of insulin gene expression in islet beta cells.
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Affiliation(s)
- Li Zhao
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
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13
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Gerrish K, Van Velkinburgh JC, Stein R. Conserved transcriptional regulatory domains of the pdx-1 gene. Mol Endocrinol 2003; 18:533-48. [PMID: 14701942 DOI: 10.1210/me.2003-0371] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The pancreas and duodenum homeobox protein 1 (PDX-1) homeodomain-containing transcription factor affects both pancreatic endocrine cell development and adult islet beta-cell function. Cell-type-specific expression is controlled by sequences 5' flanking the pdx-1 gene transcription start site. One principal control region is located roughly between -2800 and -1600 bp and spans three conserved, distinct, and functionally important subdomains, termed areas I, II, and III. In this study, we found that an upstream control region in the rat pdx-1 gene located between -6200 and -5670 bp is also present in the mouse, chicken, and human genes. This region is capable of independently directing pancreatic beta-cell-selective reporter gene expression and potentiating area I/II-driven activity. This newly recognized conserved subdomain has been termed area IV. The islet-enriched forkhead box A2 (FoxA2), NK2 homeobox 2.2 (Nkx2.2), and pancreas and duodenum homeobox protein 1 (PDX-1) transcription factors have been shown to activate area IV-driven reporter gene expression as well as bind to this region of the endogenous gene in beta-cells. Analysis of the histone H3 and H4 acetylation level also indicated that areas I-IV are within transcriptionally active chromatin in beta-cells. Our data suggests that pdx-1 transcription is also regulated by factors acting upon conserved area IV sequences.
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Affiliation(s)
- Kevin Gerrish
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, 723 Light Hall, Nashville, Tennessee 37215, USA
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14
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Samaras SE, Zhao L, Means A, Henderson E, Matsuoka TA, Stein R. The islet beta cell-enriched RIPE3b1/Maf transcription factor regulates pdx-1 expression. J Biol Chem 2003; 278:12263-70. [PMID: 12551916 DOI: 10.1074/jbc.m210801200] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Pancreatic duodenal homeobox factor-1, PDX-1, is required for pancreas development, islet cell differentiation, and the maintenance of beta cell function. Selective expression in the pancreas appears to be principally regulated by Area II, one of four conserved regulatory sequence domains found within the 5'-flanking region of the pdx-1 gene. Detailed mutagenesis studies have identified potential sites of interaction for both positive- and negative-acting factors within the conserved sequence blocks of Area II. The islet beta cell-enriched RIPE3b1 transcription factor, the activator of insulin C1 element-driven expression, was shown here to also stimulate Area II by binding to sequence blocks 4 and 5 (termed B4/5). Accordingly, B4/5 DNA-binding protein's molecular mass (i.e. 46 kDa), binding specificity, and islet beta cell-enriched distribution were identical to RIPE3b1. Area II-mediated activation was also unaffected upon replacing B4/5 with the insulin C1/RIPE3b1 binding site. In addition, the chromatin immunoprecipitation assay showed that the Area II region of the endogenous pdx-1 gene was precipitated by an antiserum that recognizes the large Maf protein that comprises the RIPE3b1 transcription factor. These results strongly suggest that RIPE3b1/Maf has an important role in generating and maintaining physiologically functional beta cells.
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Affiliation(s)
- Susan E Samaras
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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15
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Kataoka K, Han SI, Shioda S, Hirai M, Nishizawa M, Handa H. MafA is a glucose-regulated and pancreatic beta-cell-specific transcriptional activator for the insulin gene. J Biol Chem 2002; 277:49903-10. [PMID: 12368292 DOI: 10.1074/jbc.m206796200] [Citation(s) in RCA: 216] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The insulin gene is specifically expressed in beta-cells of the Langerhans islets of the pancreas, and its transcription is regulated by the circulating glucose level. Previous reports have shown that an unidentified beta-cell-specific nuclear factor binds to a conserved cis-regulatory element called RIPE3b and is critical for its glucose-regulated expression. Based on the sequence similarity of the RIPE3b element and the consensus binding sequence of the Maf family of basic leucine zipper transcription factors, we here identified mammalian homologue of avian MafA/L-Maf, an eye-specific member of the Maf family, as the RIPE3b-binding transcriptional activator. Reverse transcription-PCR analysis showed that mafA mRNA is detected only in the eyes and in pancreatic beta-cells and not in alpha-cells. MafA protein as well as its mRNA is up-regulated by glucose, consistent with the glucose-regulated binding of MafA to the RIPE3b element in beta-cell nuclear extracts. In transient luciferase assays, we also showed that expression of MafA greatly enhanced insulin promoter activity and that a dominant-negative form of MafA inhibited it. Therefore, MafA is a beta-cell-specific and glucose-regulated transcriptional activator for insulin gene expression and thus may be involved in the function and development of beta-cells as well as in the pathogenesis of diabetes.
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MESH Headings
- Amino Acid Sequence
- Animals
- Blotting, Northern
- Blotting, Western
- Cell Nucleus/metabolism
- Cloning, Molecular
- DNA, Complementary/metabolism
- Eye/cytology
- Genes, Dominant
- Glucose/metabolism
- Homeodomain Proteins
- Humans
- Insulin/genetics
- Insulin/metabolism
- Islets of Langerhans/metabolism
- Lectins, C-Type
- Luciferases/metabolism
- Maf Transcription Factors, Large
- Mice
- Microscopy, Fluorescence
- Molecular Sequence Data
- Phosphorylation
- Promoter Regions, Genetic
- Protein Binding
- Proto-Oncogene Proteins/metabolism
- RNA/metabolism
- RNA, Messenger/metabolism
- Rats
- Receptors, Immunologic
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Tissue Distribution
- Trans-Activators/chemistry
- Trans-Activators/metabolism
- Transcription, Genetic
- Up-Regulation
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Affiliation(s)
- Kohsuke Kataoka
- Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503, Japan.
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16
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Zhu M, Breslin MB, Lan MS. Expression of a novel zinc-finger cDNA, IA-1, is associated with rat AR42J cells differentiation into insulin-positive cells. Pancreas 2002; 24:139-45. [PMID: 11854618 DOI: 10.1097/00006676-200203000-00004] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
INTRODUCTION IA-1, an insulinoma-associated cDNA-1, encodes a zinc-finger DNA-binding protein originally isolated from a human insulinoma subtraction library. AIM To demonstrate the restriction of IA-1 gene expression in human fetal pancreata of different gestational stages and to determine whether the expression of IA-1 gene is associated with rat AR42J cell differentiation into insulin-positive cells. METHODOLOGY To examine whether the IA-1 gene is associated with pancreatic endocrine cell differentiation, we used a rat pancreatic amphicrine cell line, AR42J, to investigate whether the expression of the IA-1 gene coincides with AR42J cells converting into either endocrine or exocrine lineage. We also examined a set of islet transcription factors that regulate key differentiation steps involved in activating the genes that confer the specialized functions of terminally differentiated pancreatic islet cells. RESULTS When the AR42J cells were converted into insulin-positive cells induced by GLP-1, insulinoma conditioned-medium, or both, we observed a significant elevated expression of mRNA for IA-1 and islet-specific transcription factors such as Pdx-1, NeuroD/beta2, and Nkx6.1. In contrast, dramatically decreased expression of mRNA for IA-1 and islet-specific transcription factors was displayed when AR42J cells were converted into the acinar-like phenotype by dexamethasone. CONCLUSIONS IA-1 gene was shown to be developmentally regulated in fetal pancreatic cells, and its expression pattern is consistent with parallel changes in islet-specific transcription factors during the endocrine differentiation of AR42J cells.
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Affiliation(s)
- Min Zhu
- Research Institute for Children, Children's Hospital, 520 Elmwood Park Blvd., Harahan, Louisiana 70123, U.S.A
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17
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Wang JC, Waltner-Law M, Yamada K, Osawa H, Stifani S, Granner DK. Transducin-like enhancer of split proteins, the human homologs of Drosophila groucho, interact with hepatic nuclear factor 3beta. J Biol Chem 2000; 275:18418-23. [PMID: 10748198 DOI: 10.1074/jbc.m910211199] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Members of the hepatic nuclear factor 3 (HNF3) family, including HNF3alpha, HNF3beta, and HNF3gamma, play important roles in embryonic development, the establishment of tissue-specific gene expression, and the regulation of gene expression in differentiated tissues. We found, using the glutathione S-transferase pull-down method, that the transducin-like Enhancer of split (TLE) proteins, which are the human homologs of Drosophila Groucho, directly associate with HNF3beta. Conserved region II of HNF3beta (amino acids 361-388) is responsible for the interaction with TLE1. A mammalian two-hybrid assay was used to confirm that this interaction occurs in vivo. Overexpression of TLE1 in HepG2 and HeLa cells decreases transactivation mediated through the C-terminal domain of HNF3beta, and Grg5, a naturally occurring dominant negative form of Groucho/TLE, also increases the transcriptional activity of this region of HNF3. These results lead us to suggest that TLE proteins could influence the expression of mammalian genes regulated by HNF3.
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Affiliation(s)
- J C Wang
- Department of Molecular Physiology & Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-0615, USA
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18
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Gerrish K, Gannon M, Shih D, Henderson E, Stoffel M, Wright CV, Stein R. Pancreatic beta cell-specific transcription of the pdx-1 gene. The role of conserved upstream control regions and their hepatic nuclear factor 3beta sites. J Biol Chem 2000; 275:3485-92. [PMID: 10652343 DOI: 10.1074/jbc.275.5.3485] [Citation(s) in RCA: 126] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
To identify potential transactivators of pdx-1, we sequenced approximately 4.5 kilobases of the 5' promoter region of the human and chicken homologs, assuming that sequences conserved with the mouse gene would contain critical cis-regulatory elements. The sequences associated with hypersensitive site 1 (HSS1) represented the principal area of homology within which three conserved subdomains were apparent: area I (-2694 to -2561 base pairs (bp)), area II (-2139 to -1958 bp), and area III (-1879 to -1799 bp). The identities between the mouse and chicken/human genes are very high, ranging from 78 to 89%, although only areas I and III are present within this region in chicken. Pancreatic beta cell-selective expression was shown to be controlled by mouse and human area I or area II, but not area III, from an analysis of pdx-1-driven reporter activity in transfected beta- and non-beta cells. Mutational and functional analyses of conserved hepatic nuclear factor 3 (HNF3)-like sites located within area I and area II demonstrated that activation by these regions was mediated by HNF3beta. To determine if a similar regulatory relationship might exist within the context of the endogenous gene, pdx-1 expression was measured in embryonic stem cells in which one or both alleles of HNF3beta were inactivated. pdx-1 mRNA levels induced upon differentiation to embryoid bodies were down-regulated in homozygous null HNF3beta cells. Together, these results suggest that the conserved sequences represented by areas I and II define the binding sites for factors such as HNF3beta, which control islet beta cell-selective expression of the pdx-1 gene.
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Affiliation(s)
- K Gerrish
- Department of Molecular Physiology, Vanderbilt Medical Center, Nashville, Tennessee 37232, USA
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19
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Sayo Y, Hosokawa H, Imachi H, Murao K, Sato M, Wong NC, Ishida T, Takahara J. Transforming growth factor beta induction of insulin gene expression is mediated by pancreatic and duodenal homeobox gene-1 in rat insulinoma cells. EUROPEAN JOURNAL OF BIOCHEMISTRY 2000; 267:971-8. [PMID: 10672004 DOI: 10.1046/j.1432-1327.2000.01080.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Although transforming growth factor-beta (TGF-beta) stimulates pancreatic islet cells to synthesize and secret insulin, the mechanism underlying this effect is not known. To investigate this question, we examined the insulin promoter activity focusing on a transcription factor, pancreatic and duodenal homeobox gene-1 (PDX-1) that binds to the A3 element of the rat insulin promoter. Studies performed using the rat insulinoma cell line, INS-1 showed that TGF-beta stimulation of endogenous insulin mRNA expression correlated with increased activity of a reporter construct containing the insulin promoter. A potential mechanism for this increase arose from, electrophoretic mobility shift assay showing that the nuclear extract from TGF-beta treated cells contained higher levels of A3 binding activity. Western blot analysis confirmed that PDX-1 was increased in the nuclear extract from INS-1 cells treated with TGF-beta. As expected, a mutant insulin promoter that lacked the PDX-1 binding site was not stimulated by TGF-beta. In summary, the results of these studies show that TGF-beta stimulates the transcription of insulin gene and this action is mediated by the transcription factor, PDX-1.
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Affiliation(s)
- Y Sayo
- First Department of Internal Medicine, Kagawa Medical University, Kagawa, Japan.
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20
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Bramblett DE, Huang HP, Tsai MJ. Pancreatic islet development. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 1999; 47:255-315. [PMID: 10582089 DOI: 10.1016/s1054-3589(08)60114-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- D E Bramblett
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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21
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Tomonari A, Yoshimoto K, Mizusawa N, Iwahana H, Itakura M. Differential regulation of the human insulin gene transcription by GG1 and GG2 elements with GG- and C1-binding factors. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1446:233-42. [PMID: 10524198 DOI: 10.1016/s0167-4781(99)00096-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Using a human growth hormone reporter system, the introduced mutations in GG1 alone or both GG elements of GG1 and GG2 in the human insulin promoter abolished 94 or 96% of the beta-cell-specific transcriptional activity in a pancreatic islet beta-cell line of MIN6, while the mutations in GG2 or its total deletion abolished 85 or 86% of the transcriptional activity. When linked to the thymidine kinase promoter, mutations in GG1 or both GG elements abolished 74% of the transcriptional activity in MIN6 cells, while the mutations in GG2 or its total deletion abolished 55 or 54%. In the electrophoretic mobility shift assay (EMSA), one nuclear factor was shown to interact with two GG elements, and another C1-binding factor with GG1 and C1. The differential effects of deletions or selective mutations in the GG2 or GG1 sequence in the oligonucleotide probes on the binding activity of GG- or C1-binding factors in EMSA proved the requirement of both GG1 and GG2 or both GG1 and C1, respectively, for the transaction of these two factors. The molecular size of the GG-binding factor was estimated about 30 kDa. Based on these, we conclude that two GG elements contribute, with GG1 more critically than GG2, to the beta-cell-specific transcription of the human insulin gene through transaction with the GG- and C1-binding factors.
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Affiliation(s)
- A Tomonari
- Otsuka Department of Molecular Nutrition, School of Medicine, University of Tokushima, Japan
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22
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Sharma A, Henderson E, Gamer L, Zhuang Y, Stein R. Analysis of the role of E2A-encoded proteins in insulin gene transcription. Mol Endocrinol 1997; 11:1608-17. [PMID: 9328343 DOI: 10.1210/mend.11.11.0004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Pancreatic beta-cell type-specific transcription of the insulin gene is mediated, in part, by factors in the basic helix-loop-helix (bHLH) family that act on a site within the insulin enhancer, termed the E1-box. Expression from this element is regulated by a heteromeric protein complex containing ubiquitous (i.e. the E2A- and HEB-encoded proteins) and islet-enriched members of the bHLH family. Recent studies indicate that the E2A- and HEB-encoded proteins contain a transactivation domain, termed AD2, that functions more efficiently in transfected beta-cell lines. In the present report, we extend this observation by demonstrating that expression of full-length E2A proteins (E47, E12, and E2/5) activates insulin E element-directed transcription in a beta-cell line-selective manner. Stimulation required functional interactions with other key insulin gene transcription factors, including its islet bHLH partner as well as those that act on the RIPE3b1 and RIPE3a2 elements of the insulin gene enhancer. The conserved AD2 domain in the E2A proteins was essential in this process. The effect of the E2A- and HEB-encoded proteins on insulin gene expression was also analyzed in mice lacking a functional E2A or HEB gene. There was no apparent difference in insulin production between wild type, heterozygote, and homozygous mutant E2A or HEB mice. These results suggest that neither the E2A- or HEB-encoded proteins are essential for insulin transcription and that one factor can substitute for the other to impart normal insulin E1 activator function in mutant animals.
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Affiliation(s)
- A Sharma
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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23
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Li Q, Notkins AL, Lan MS. Molecular characterization of the promoter region of a neuroendocrine tumor marker, IA-1. Biochem Biophys Res Commun 1997; 236:776-81. [PMID: 9245732 DOI: 10.1006/bbrc.1997.7054] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
IA-1 is an intronless gene, which encodes a 510 amino acid protein with a zinc-finger DNA-binding motif that is expressed in tumors of neuroendocrine origin. The 5'-upstream region of the IA-1 gene was recently sequenced. In this paper, the regulatory elements and the promoter region of the 5'-upstream region were analyzed by use of a series of deletion mutants (ranging from +26 bp to -2090 bp upstream of the IA-1 gene), which were tested in a pituitary tumor cell line, AtT-20, and Hela cells by transient transfection assays. These experiments showed that a 506 base pair upstream sequence was sufficient for maximal expression of a reporter gene. Multiple known regulatory elements were found within this region including three E boxes and a clustered Sp-1 site. In addition, Southwestern blot analysis, using a radiolabeled promoter sequence (extending from -108 bp to -66 bp) and nuclear extracts from both neuroendocrine and non-neuroendocrine cell lines, revealed four promoter binding proteins designated PBP1, PBP2, PBP3 and PBP4 with molecular weights of 55 kD, 32 kD, 29 kD, and 27/28 kD, respectively. These studies suggest that several different regulatory elements in the 5'-upstream region of the IA-1 gene and at least four different nuclear proteins may be involved in the cell-specific expression of IA-1.
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Affiliation(s)
- Q Li
- Oral Infection and Immunity Branch, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA
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24
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Whelan J, Miller N. Generation of estrogen receptor mutants with altered ligand specificity for use in establishing a regulatable gene expression system. J Steroid Biochem Mol Biol 1996; 58:3-12. [PMID: 8809181 DOI: 10.1016/0960-0760(96)00010-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Considerable interest exists in developing an artificial system for the control of gene expression, based on the hormone binding domain (HBD) of steroid receptors. In this study we describe a yeast based approach which allows the identification of mutations within the HBD of steroid receptors, in this case the estrogen receptor, which result in altered specificity of the HBD with respect to its activation by ligands. Using this approach in yeast, we identified an estrogen receptor (HBD) mutant (His524 to Gln) whose activation by 17 beta-estradiol (E2) is significantly reduced while activation by a diphenol indene-ol compound (GR132706X) is increased, compared to the wild type estrogen receptor. When the activity of the mutant receptor was tested in mammalian cells the altered specificity was maintained. A chimeric transcription factor was constructed, in which the mutated estrogen receptor HBD was linked to the DNA binding domain of GAL4 and an 11 amino acid transcriptional activation domain of RelA. Reporter gene activation by this chimera was decreased in response to E2 and increased in response to GR132706X, as compared to the corresponding chimeric transcription factor containing the wild type estrogen receptor HBD. This approach should allow the development of a steroid receptor HBD based regulator of gene expression, whose activity is controlled specifically by a synthetic ligand, that would not affect the activity of endogenous steroid receptors.
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Affiliation(s)
- J Whelan
- Glaxo Institute for Molecular Biology, Plan-Les-Ouates Geneva, Switzerland
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25
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Odagiri H, Wang J, German MS. Function of the human insulin promoter in primary cultured islet cells. J Biol Chem 1996; 271:1909-15. [PMID: 8567638 DOI: 10.1074/jbc.271.4.1909] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Pancreatic islet beta cells regulate the rate of insulin gene transcription in response to a number of nutrients, the most potent of which is glucose. To test for its regulation by glucose, the promoter sequence was isolated from the human insulin gene. When linked to chloramphenicol acetyltransferase and transfected into primary islet cultures, the human insulin promoter is activated by glucose. In parallel islet transfections, glucose also activates the L-pyruvate kinase and islet amyloid chain ketoacid dehydrogenase E1a promoter, but it does not affect the beta cell glucose kinase promoter. Using deletion and substitution mutations of the proximal human insulin promoter, we mapped a metabolic response element to the E box, E1, at -100 base pairs relative to the transcription start site. Although the isolated E1 element responds to glucose, inclusion of either of two AT-rich sequences, A1 or A2/C1 on either side of E1, results in dramatic synergistic activation. Inclusion of A2/C1 also increases the response to glucose. The A2-E1-A1 region alone, however, does not explain all of the activity of the human insulin promoter in cultured islets, and other transcriptionally important elements likely to contribute to the glucose response as well.
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Affiliation(s)
- H Odagiri
- Hormone Research Institute, University of California at San Francisco 94143-0534, USA
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26
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Shieh SY, Stellrecht CM, Tsai MJ. Molecular characterization of the rat insulin enhancer-binding complex 3b2. Cloning of a binding factor with putative helicase motifs. J Biol Chem 1995; 270:21503-8. [PMID: 7665561 DOI: 10.1074/jbc.270.37.21503] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Cell-specific expression of the rat insulin II gene is in part mediated through an element located in the 5'-flanking region. The element, termed RIPE3b (-126 to -101), confers beta-cell-specific expression in conjunction with an adjacent element RIPE3a (-110 to -86). Here we report the characterization of one of the RIPE3b-binding complexes, 3b2. UV cross-linking analysis demonstrated that it is composed of at least three polypeptides: p58, p62, and p110. Furthermore, a cDNA was isolated via expression screening for binding to RIPE3b. Sequence analysis reveals that the encoded protein, designated Rip-1, possessed putative helicase motifs and a potential transcription activation domain. Overexpression of Rip-1 in cells greatly enhances the 3b2 binding complex, suggesting that Rip-1 is involved in the binding of 3b2.
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Affiliation(s)
- S Y Shieh
- Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA
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27
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Clark AR, Wilson ME, Leibiger I, Scott V, Docherty K. A Silencer and an Adjacent Positive Element Interact to Modulate the Activity of the Human Insulin Promoter. ACTA ACUST UNITED AC 1995. [DOI: 10.1111/j.1432-1033.1995.tb20853.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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28
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Philippe J, Morel C, Cordier-Bussat M. Islet-specific proteins interact with the insulin-response element of the glucagon gene. J Biol Chem 1995; 270:3039-45. [PMID: 7531697 DOI: 10.1074/jbc.270.7.3039] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Glucagon gene expression is negatively regulated by insulin at the transcriptional level. G3, a DNA control element located in the 5'-flanking sequence of the rat glucagon gene mediates the inhibition of transcription, which occurs in response to insulin. We show here that two islet-specific protein complexes C1A and C1B, bind to the A domain of G3, which is critical for the insulin response. These two complexes bind to overlapping sequences of the A domain and display very similar binding specificities. Point mutations in the A domain that affect binding of C1A and C1B result in both decreased G3 enhancer activity and insulin-mediated inhibitory effects with a close correlation between diminution of binding and function. One of the two complexes, C1A, is similar or identical to B1, a protein complexes interacting with the upstream promoter element of the glucagon gene, G1, implicated in the A cell-specific expression of the glucagon gene. Our data indicate that islet-specific proteins are involved in glucagon gene regulation by insulin.
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Affiliation(s)
- J Philippe
- Department of Genetics and Microbiology, University of Geneva Medical School, Switzerland
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29
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Melloul D, Cerasi E. Transcription of the insulin gene: towards defining the glucose-sensitive cis-element and trans-acting factors. Diabetologia 1994; 37 Suppl 2:S3-10. [PMID: 7821736 DOI: 10.1007/bf00400820] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Previous work has shown that the sequence -196 to -247 of the rat insulin I gene mediates the stimulatory effect of glucose in fetal islets. We have used adult rat and human islets to delineate the glucose-sensitive cis-element to the sequence -193 to -227. In electrophoretic mobility shift assays, a 22 bp nucleotide corresponding to the sequence -206 to -227 bound all the nuclear proteins that could be bound by the entire minienhancer sequence -196 to -247. The rat insulin I sequence -206 to -227 formed three major complexes; in contrast, the corresponding human insulin sequence formed one single band with human and rat islet nuclear extracts, corresponding to the complex C1 of the rat insulin gene. Incubation of islets with varying glucose levels resulted in a dose-dependent increase in the intensity of the C1 band, while the other nuclear complexes formed with the insulin sequence, or the AP1 and SP1 binding activities used as control, were glucose insensitive. This is thus the first demonstration of a physiologic glucose-sensitive trans-acting factor for the insulin gene, whose further study may markedly enhance our understanding of the regulation of insulin biosynthesis in normal and diabetic beta cells. Furthermore, once cloned, the introduction of this glucose sensitive factor may enable the construction of truly physiologic artificial beta cells.
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Affiliation(s)
- D Melloul
- Department of Endocrinology and Metabolism, Hebrew University Hadassah Medical Center, Jerusalem, Israel
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30
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Rommel C, Leibiger IB, Leibiger B, Walther R. CT-boxes are involved in control of the rat insulin II gene expression. FEBS Lett 1994; 345:17-22. [PMID: 8194592 DOI: 10.1016/0014-5793(94)00430-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Expression of the rat insulin II gene is controlled mainly at the level of transcription initiation by multiple factors binding to specific cis-acting DNA-elements in the regulatory region. We have shown that two elements (CT-motifs) located between nucleotides -83 and -76 (CT-1) and -204 and -197 (CT-2) are involved in transcriptional regulation in the insulin-producing cell line HIT M2.2.2. Transient expression analysis of 5'-deletion as well as block replacement mutants revealed that CT-1 and CT-2 are mutational sensitive. Gel mobility shift assays showed that both motifs bind similar nuclear factors. Our results suggest the involvement of a third CT-motif located directly upstream of CT-2 on the complementary strand.
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Affiliation(s)
- C Rommel
- Institut für Biochemie, Medizinische Fakultät, Ernst-Moritz-Arndt-Universität Greifswald, Germany
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31
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Stein R, Henderson E, Cordle SR. Analysis of an insulin gene transcription control element. Positive and negative regulation appears to be mediated by different element sequences. FEBS Lett 1994; 338:187-90. [PMID: 8307179 DOI: 10.1016/0014-5793(94)80362-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Pancreatic beta-cell-type-specific transcription of the insulin gene is controlled by cis-acting sequence elements lying within its enhancer region. An essential element required for expression is the insulin control element (ICE). The activity of this element is regulated by both positive- and negative-acting transcription factors. In this study, we have identified the nucleotide sequences within the ICE that are required for repression in noninsulin producing cells. Our results indicate that the cis-acting sequences involved in negative control are distinct from those required in activating expression in beta cells.
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Affiliation(s)
- R Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, TN 37232
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32
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Leibiger IB, Walther R, Pett U, Leibiger B. Positive and negative regulatory elements are involved in transcriptional control of the rat glucokinase gene in the insulin producing cell line HIT M2.2.2. FEBS Lett 1994; 337:161-6. [PMID: 8287971 DOI: 10.1016/0014-5793(94)80265-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Nested deletion mutants of the 5' flanking region of the beta-cell transcription unit of the rat glucokinase gene (r beta GK) were fused to the CAT-reporter gene. Transient expression studies in HIT M2.2.2 and BHK21 cells revealed a distal (upstream of -359) and a proximal promoter region (between -278/-49) harbouring positive and negative regulatory elements. DNaseI footprinting revealed three protected areas between nucleotides -190 and -60. DNA-elements playing a crucial role in transcriptional control of the insulin genes (IEB- and CT-motifs) have been detected within the proximal promoter region and contribute to beta-cell specific gene regulation. 3' deletion analysis revealed that DNA-elements located downstream from transcription initiation sites (up to +123) contribute to transcriptional regulation.
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Affiliation(s)
- I B Leibiger
- Institut für Biochemie, Klinikum, Medizinische Fakultät, Ernst-Moritz-Arndt-Universität Greifswald, Germany
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33
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ATF-a0, a novel variant of the ATF/CREB transcription factor family, forms a dominant transcription inhibitor in ATF-a heterodimers. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42236-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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34
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Robinson G, Peshavaria M, Henderson E, Shieh S, Tsai M, Teitelman G, Stein R. Expression of the trans-active factors that stimulate insulin control element-mediated activity appear to precede insulin gene transcription. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)41967-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Abstract
Selective transcription of the insulin gene in pancreatic beta cells is regulated by its enhancer, located between nucleotides -340 to -91 relative to the transcription start site. The activity o f the enhancer is controlled by both positive- and negative-acting cellular factors. Cell-type-specific expression is mediated principally by a single cis-acting enhancer element, termed the insulin control element (ICE), which is acted upon by both these cellular activities. This review focuses on the role of the factors acting on the ICE and other enhancer control elements in the establishment of cell-type-specific and physiologically regulated transcription of the insulin gene.
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Affiliation(s)
- R Stein
- Department of Molecular Physiology and Biophysics, Vanderbilt Medical Center, Nashville, TN 37232, USA
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36
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Hooft van Huijsduijnen R, Whelan J, Pescini R, Becker-André M, Schenk A, DeLamarter J. A T-cell enhancer cooperates with NF-kappa B to yield cytokine induction of E-selectin gene transcription in endothelial cells. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)41683-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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37
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Leshkowitz D, Aronheim A, Walker MD. Insulin-producing cells contain a cell-specific repressor activity that functions through multiple E-box sequences. DNA Cell Biol 1992; 11:549-58. [PMID: 1388727 DOI: 10.1089/dna.1992.11.549] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The cis-acting DNA element known as the E box (consensus sequence CAxxTG) plays an important role in the transcription of a number of cell-specifically expressed genes. The rat insulin I gene, for example, contains two such sequences (IEB1 and IEB2) that are recognized specifically by a characteristic beta cell nuclear factor insulin enhancer factor 1 (IEF1). To define the role of these elements better, we tested for cooperative interactions between the IEB sequences. Transfection experiments were performed with a series of plasmids containing the elements separated by different distances. Transcriptional activity in vivo is only modestly affected (less than two-fold) when the distances between the IEB elements are changed by a half-integral number of double-helical turns. Surprisingly, plasmids bearing four and six copies of the IEB motif showed sharply reduced activity as compared to those with two copies. In vitro DNA-binding studies revealed that this effect was not due to inability of IEF1 to bind to multiple copies of IEB. Moreover, multiple copies of the IEB sequence were able to inhibit activity of a cis-linked Moloney sarcoma virus (MSV) or insulin enhancer upon transfection to beta cells but not to other cell types. The above data are consistent with the view that beta cells contain a cell-specific repressor molecule capable of binding to multiple copies of IEB and thereby inhibiting transcription. This interpretation was further strengthened by in vivo competition and trans-activation experiments. The beta-cell-specific repressor activity identified by these studies may play an important role in mediating gene expression in insulin-producing cells, perhaps by regulating the access of helix-loop-helix transcription factors to E-box sequence elements.
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Affiliation(s)
- D Leshkowitz
- Department of Biochemistry, Weizmann Institute of Science, Rehovot, Israel
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38
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Subunit structure of cell-specific E box-binding proteins analyzed by quantitation of electrophoretic mobility shift. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)49584-7] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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39
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Salhany KE, Robinson-Benion C, Candia AF, Pledger WJ, Holt JT. Differential induction of the c-fos promoter through distinct PDGF receptor-mediated signaling pathways. J Cell Physiol 1992; 150:386-95. [PMID: 1310326 DOI: 10.1002/jcp.1041500223] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The multiple isoforms of PDGF induce fibroblastic mitogenesis through two distinct PDGF receptors, alpha and beta. The molecular mechanisms by which these alpha and beta PDGF receptors regulate gene expression are poorly understood. We present data which indicates that differential induction of c-fos gene expression by PDGF isoforms occurs through distinct PDGF alpha and beta receptor-mediated signaling pathways. Comparison of PDGF-AA with PDGF-BB stimulation showed that PDGF-BB induced prolonged expression of the c-fos gene in BALB/c-3T3 cells, but that PDGF-AA induced more potent activation of the serum response element (SRE) in transient transfection assays. PDGF-AA, which binds alpha but not beta PDGF receptors, could only induce the SRE through a protein kinase C (PKC)-dependent pathway, whereas PDGF-BB, which binds both alpha and beta PDGF receptors, could also induce the SRE through a PKC-independent pathway. These results suggest that PDGF alpha receptors activate the PKC-dependent signaling pathway while PDGF beta receptors also activate a PKC-independent pathway. In addition, we found that PDGF-BB could induce another c-fos promoter element within the -90 to +10 region, suggesting that the more potent mitogenic effect and prolonged c-fos gene expression induced by PDGF-BB may result from cooperativity between more than one c-fos promoter elements.
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Affiliation(s)
- K E Salhany
- Department of Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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40
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Takahashi S, Fukamizu A, Hasegawa T, Yokoyama M, Nomura T, Katsuki M, Murakami K. Expression of the human angiotensinogen gene in transgenic mice and transfected cells. Biochem Biophys Res Commun 1991; 180:1103-9. [PMID: 1659395 DOI: 10.1016/s0006-291x(05)81180-5] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have generated two lines of transgenic mice with integrated copies of a 14-kilobase pair (kb) human DNA fragment containing the angiotensinogen gene, which includes 1.3 kb of 5'- and 3'-flanking regions. In both transgenic lines, a considerable quantity of the correctly initiated and processed angiotensinogen mRNA was detected in the liver and it was detectable in heart. Unexpectedly, mRNA for the transgene was accumulated in the kidney, where is normally the minor source of angiotensinogen, to levels comparable to that in the liver. In addition, an in vitro transfection analysis suggested that the 1.3-kb 5'-flanking sequences are essential for expression of the angiotensinogen gene in hepatic and renal cells and that neither DNA segment within the 14-kb construct contributes significantly to repression of the gene expression in renal cells.
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Affiliation(s)
- S Takahashi
- Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan
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41
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Scott V, Clark AR, Hutton JC, Docherty K. Two proteins act as the IUF1 insulin gene enhancer binding factor. FEBS Lett 1991; 290:27-30. [PMID: 1915886 DOI: 10.1016/0014-5793(91)81217-v] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
IUF1 is a pancreatic beta cell-specific factor which binds to the sequence 5'-CPyCTAATG-3' (CT box) within the human insulin gene enhancer. Here we show that IUF1 is composed of 2 binding activities that can be separated by DEAE ion exchange chromatography. South Western blot analysis indicates that these distinct binding activities have apparent molecular weights of 115 kDa and 46 kDa.
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Affiliation(s)
- V Scott
- Department of Medicine, University of Birmingham, Queen Elizabeth Hospital, UK
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42
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Shieh S, Tsai M. Cell-specific and ubiquitous factors are responsible for the enhancer activity of the rat insulin II gene. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)55359-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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43
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Efrat S, Surana M, Fleischer N. Glucose induces insulin gene transcription in a murine pancreatic beta-cell line. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99139-8] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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44
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Besnard C, Monthioux E, Loràs P, Jami J, Daegelen D. Extinction of the human insulin gene expression in insulinoma x fibroblast somatic cell hybrids involves cis-acting DNA elements. J Cell Physiol 1991; 146:349-55. [PMID: 2022690 DOI: 10.1002/jcp.1041460303] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Insulin gene expression in rat insulinoma (RIN) cells is extinct in RIN x fibroblast hybrids and can reappear upon loss of DNA contributed by the fibroblast parent. (Besnard et al., Exp. Cell Res. 185:101-108, 1989). In the present study, we looked for the role of 5'-flanking sequences of the human insulin gene in the negative control observed in the hybrids. RIN cells were transformed with composite genes which consisted of the coding sequence of the gpt gene placed under the control of 5'-flanking regions of the human insulin gene (Ins.gpt gene). Upon hybridization of these cells with mouse fibroblasts, the expression of both Ins.gpt and endogenous rat insulin genes were suppressed together. The results obtained indicate that cis-acting DNA elements are involved in the negative control of the gene. These elements are located in a fragment spread from -258 to +241 of the transcription origin of the human insulin gene.
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Affiliation(s)
- C Besnard
- Unité INSERM 257, Institut Jacques Monod du CNRS, Université Paris VII, France
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45
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Teitelman G. Cellular and molecular analysis of pancreatic islet cell lineage and differentiation. RECENT PROGRESS IN HORMONE RESEARCH 1991; 47:259-94; discussion 294-7. [PMID: 1745822 DOI: 10.1016/b978-0-12-571147-0.50012-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- G Teitelman
- Department of Neurology, Cornell University Medical College, New York, New York 10021
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46
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German MS, Moss LG, Rutter WJ. Regulation of insulin gene expression by glucose and calcium in transfected primary islet cultures. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)45666-9] [Citation(s) in RCA: 104] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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47
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Mosselman S, Höppener JW, de Wit L, Soeller W, Lips CJ, Jansz HS. IAPP/amylin gene transcriptional control region: evidence for negative regulation. FEBS Lett 1990; 271:33-6. [PMID: 2172004 DOI: 10.1016/0014-5793(90)80365-p] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Aberrant expression of the islet amyloid polypeptide (IAPP) gene might be involved in the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM). Here, we report that IAPP promoter-luciferase constructs revealed tissue-specific activity. This activity was not mediated by cAMP. Sequential 5' deletions of the IAPP promoter caused a progressive derepression of the IAPP gene promoter in IAPP-producing cells. Comparison of the nucleotide sequence of the IAPP promoter with that of the insulin promoter (both active in pancreatic beta-cells) reveals two sequence elements of putative importance: an insulin enhancer-like sequence and an element which corresponds to a protected domain in rat insulin I gene promoter footprint experiments.
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Affiliation(s)
- S Mosselman
- Institute of Molecular Biology and Medical Biotechnology, Utrecht, The Netherlands
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48
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49
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Shibasaki Y, Sakura H, Takaku F, Kasuga M. Insulin enhancer binding protein has helix-loop-helix structure. Biochem Biophys Res Commun 1990; 170:314-21. [PMID: 2196879 DOI: 10.1016/0006-291x(90)91276-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Insulin gene expression is restricted to pancreatic B cells and the 5' flanking region is responsible for the tissue specificity. The GCCATCTG motif in this region of the rat insulin 1 gene functions as an enhancer for insulin transcription. A cDNA coding for a GCCATCTG motif-binding protein (IEBP1) was isolated from a rat pancreatic B cell tumor lambda gt11 library. The IEBP1 protein was found to be the rat counterpart of the immunoglobulin (Ig) enhancer binding protein E12/47 having a helix-loop-helix domain. This result indicates that the Ig gene and insulin gene employ the same (or a similar) binding protein as a part of their transcriptional apparatus.
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Affiliation(s)
- Y Shibasaki
- Third Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan
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50
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Boam DS, Clark AR, Docherty K. Positive and negative regulation of the human insulin gene by multiple trans-acting factors. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39070-2] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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