scholarly journals The NeuroD1/BETA2 Sequences Essential for Insulin Gene Transcription Colocalize with Those Necessary for Neurogenesis and p300/CREB Binding Protein Binding

1999 ◽  
Vol 19 (1) ◽  
pp. 704-713 ◽  
Author(s):  
Arun Sharma ◽  
Melissa Moore ◽  
Edoardo Marcora ◽  
Jacqueline E. Lee ◽  
Yi Qiu ◽  
...  
Keyword(s):  
Gene Transcription ◽  
Binding Protein ◽  
Ectopic Expression ◽  
Amino Acid Sequences ◽  
Insulin Gene ◽  
Creb Binding Protein ◽  
Β Cells ◽  
Helix Loop Helix ◽  
Transactivation Domains ◽  
Neuronal Precursors

ABSTRACT NeuroD1/BETA2 is a key regulator of pancreatic islet morphogenesis and insulin hormone gene transcription in islet β cells. This factor also appears to be involved in neurogenic differentiation, because NeuroD1/BETA2 is able to induce premature differentiation of neuronal precursors and convert ectoderm into fully differentiated neurons upon ectopic expression in Xenopus embryos. We have identified amino acid sequences in mammalian and Xenopus NeuroD1/BETA2 that are necessary for insulin gene expression and ectopic neurogenesis. Our results indicate that evolutionarily conserved sequences spanning the basic helix-loop-helix (amino acids [aa] 100 to 155) and C-terminal (aa 156 to 355) regions are important for both of these processes. The transactivation domains (AD1, aa 189 to 299; AD2, aa 300 to 355) were within the carboxy-terminal region, as analyzed by using GAL4:NeuroD1/BETA2 chimeras. Selective activation of mammalian insulin gene enhancer-driven expression and ectopic neurogenesis in Xenopus embryos was regulated by two independent and separable domains of NeuroD1/BETA2, located between aa 156 to 251 and aa 252 to 355. GAL4:NeuroD1/BETA2 constructs spanning these sequences demonstrated that only aa 252 to 355 contained activation domain function, although both aa 156 to 251 and 300 to 355 were found to interact with the p300/CREB binding protein (CBP) coactivator. These results implicate p300/CBP in NeuroD1/BETA2 function and further suggest that comparable mechanisms are utilized to direct target gene transcription during differentiation and in adult islet β cells.

scholarly journals Insulin Gene Transcription Is Mediated by Interactions between the p300 Coactivator and PDX-1, BETA2, and E47

2002 ◽  
Vol 22 (2) ◽  
pp. 412-420 ◽  
Author(s):  
Yi Qiu ◽  
Min Guo ◽  
Suming Huang ◽  
Roland Stein
Keyword(s):  
Dna Binding ◽  
Rna Polymerase Ii ◽  
Gene Transcription ◽  
Present Report ◽  
Amino Acid Sequences ◽  
Insulin Gene ◽  
Homeodomain Protein ◽  
Β Cells ◽  
Β Cell ◽  
Insulin Gene Transcription

ABSTRACT Pancreatic β-cell-type-specific expression of the insulin gene requires both ubiquitous and cell-enriched activators, which are organized within the enhancer region into a network of protein-protein and protein-DNA interactions to promote transcriptional synergy. Protein-protein-mediated communication between DNA-bound activators and the RNA polymerase II transcriptional machinery is inhibited by the adenovirus E1A protein as a result of E1A’s binding to the p300 coactivator. E1A disrupts signaling between the non-DNA-binding p300 protein and the basic helix-loop-helix DNA-binding factors of insulin’s E-element activator (i.e., the islet-enriched BETA2 and generally distributed E47 proteins), as well as a distinct but unidentified enhancer factor. In the present report, we show that E1A binding to p300 prevents activation by insulin’s β-cell-enriched PDX-1 activator. p300 interacts directly with the N-terminal region of the PDX-1 homeodomain protein, which contains conserved amino acid sequences essential for activation. The unique combination of PDX-1, BETA2, E47, and p300 was shown to promote synergistic activation from a transfected insulin enhancer-driven reporter construct in non-β cells, a process inhibited by E1A. In addition, E1A inhibited the level of PDX-1 and BETA2 complex formation in β cells. These results indicate that E1A inhibits insulin gene transcription by preventing communication between the p300 coactivator and key DNA-bound activators, like PDX-1 and BETA2:E47.

scholarly journals Crosstalk of CREB and Fos/Jun on a single cis-element: transcriptional repression of the steroidogenic acute regulatory protein gene

2007 ◽  
Vol 39 (4) ◽  
pp. 261-277 ◽  
Author(s):  
Pulak R Manna ◽  
Douglas M Stocco
Keyword(s):  
Transcriptional Repression ◽  
Protein Gene ◽  
Binding Protein ◽  
Regulatory Protein ◽  
Ectopic Expression ◽  
Fine Tuning ◽  
Creb Binding Protein ◽  
Loss Of Function ◽  
Cis Element ◽  
Steroidogenic Acute Regulatory

AbstractTranscriptional regulation of the steroidogenic acute regulatory (StAR) protein gene by cAMP-dependent mechanisms occurs in the absence of a consensus cAMP-response element (CRE; TGACGTCA) and is mediated by several sequence-specific transcription factors. We previously identified three CRE-like sites (within the −151/−1 bp cAMP-responsive region of the mouse StAR gene), of which the CRE2 site overlaps with an activator protein-1 (AP-1) motif (TGACTGA, designated as CRE2/AP-1) that can bind both CRE and AP-1 DNA-binding proteins. The present studies were aimed at exploring the functional crosstalk between CREB (CRE-binding protein) and cFos/cJun (AP-1 family members) on the CRE2/AP-1 element and its role in regulating transcription of the StAR gene. Using MA-10 mouse Leydig tumor cells, we demonstrate that the CRE and AP-1 families of proteins interact with the CRE2/AP-1 sequence. CREB, cFos, and cJun proteins were found to bind to the CRE2/AP-1 motif but not the CRE1 and CRE3 sites. Treatment with the cAMP analog (Bu)2cAMP augmented phosphorylation of CREB (Ser133), cFos (Thr325), and cJun (ser73). Chromatin immunoprecipitation studies revealed that the induction of CREB, cFos, and cJun by (Bu)2cAMP was correlated with protein–DNA interactions and recruitment of the coactivator CREB-binding protein (CBP) to the StAR promoter. EMSA studies employing CREB and cFos/cJun proteins demonstrated competition between these factors for binding to the CRE2/AP-1 motif. Transfection of cells containing the −151/−1 StAR reporter with CREB and cFos/cJun resulted in trans-repression of the StAR gene, an event tightly associated with CBP, demonstrating that both CREB and Fos/Jun compete with each other for binding with limited amounts of intracellular CBP. Overexpression of adenovirus E1A, which binds and inactivates CBP, markedly suppressed StAR gene expression. Ectopic expression of CBP eliminated the repression of the StAR gene by E1A and potentiated the activity of CREB and cFos/cJun on StAR promoter responsiveness. These findings identify molecular events involved in crosstalk between CREB and cFos/cJun, which confer both gain and loss of function on a single cis-element in fine-tuning of the regulatory events involved in transcription of the StAR gene.

scholarly journals Analysis of the Steroid Receptor Coactivator 1 (SRC1)-CREB Binding Protein Interaction Interface and Its Importance for the Function of SRC1

2001 ◽  
Vol 21 (1) ◽  
pp. 39-50 ◽  
Author(s):  
Hilary M. Sheppard ◽  
Janet C. Harries ◽  
Sagair Hussain ◽  
Charlotte Bevan ◽  
David M. Heery
Keyword(s):  
Binding Protein ◽  
Steroid Receptor ◽  
Creb Binding Protein ◽  
Interaction Domain ◽  
Steroid Receptor Coactivator ◽  
Helix Loop Helix ◽  
Rich Domain ◽  
Interaction Interface ◽  
Acetyltransferase Domain

ABSTRACT The transcriptional activity of nuclear receptors is mediated by coactivator proteins, including steroid receptor coactivator 1 (SRC1) and its homologues and the general coactivators CREB binding protein (CBP) and p300. SRC1 contains an activation domain (AD1) which functions via recruitment of CBP and and p300. In this study, we have used yeast two-hybrid and in vitro interaction-peptide inhibition experiments to map the AD1 domain of SRC1 to a 35-residue sequence potentially containing two α-helices. We also define a 72-amino-acid sequence in CBP necessary for SRC1 binding, designated the SRC1 interaction domain (SID). We show that in contrast to SRC1, direct binding of CBP to the estrogen receptor is weak, suggesting that SRC1 functions primarily as an adaptor to recruit CBP and p300. In support of this, we show that the ability of SRC1 to enhance ligand-dependent nuclear receptor activity in transiently transfected cells is dependent upon the integrity of the AD1 region. In contrast, the putative histone acetyltransferase domain, the Per-Arnt-Sim basic helix-loop-helix domain, the glutamine-rich domain, and AD2 can each be removed without loss of ligand-induced activity. Remarkably, a construct corresponding to residues 631 to 970, which contains only the LXXLL motifs and the AD1 region of SRC1, retained strong coactivator activity in our assays.

Ectopic expression of cyclin D1 prevents activation of gene transcription by myogenic basic helix-loop-helix regulators

1994 ◽  
Vol 14 (8) ◽  
pp. 5259-5267
Author(s):  
S S Rao ◽  
C Chu ◽  
D S Kohtz
Keyword(s):  
Cell Cycle ◽  
Cyclin D1 ◽  
Gene Transcription ◽  
Transcriptional Activation ◽  
Ectopic Expression ◽  
Binding Motif ◽  
Dependent Manner ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Muscle Gene

Activation of muscle gene transcription in differentiating skeletal myoblasts requires their withdrawal from the cell cycle. The effects of ectopic cyclin expression on activation of muscle gene transcription by myogenic basic helix-loop-helix (bHLH) regulators were investigated. Ectopic expression of cyclin D1, but not cyclins A, B1, B2, C, D3, and E, inhibited transcriptional activation of muscle gene reporter constructs by myogenic bHLH regulators in a dose-dependent manner. Ectopic expression of cyclin D1 inhibited the activity of a myogenic bHLH regulator mutant lacking the basic region protein kinase C site, indicating that phosphorylation of this site is not relevant to the mechanism of inhibition. Analysis of cyclin D1 mutants revealed that the C-terminal acidic region was required for inhibition of myogenic bHLH regulator activity, whereas an intact N-terminal pRb binding motif was not essential. Together, these results implicate expression of cyclin D1 as a central determinant of a putatively novel mechanism that links positive control of cell cycle progression to negative regulation of genes expressed in differentiated myocytes.

Short-term regulation of insulin gene transcription

2002 ◽  
Vol 30 (2) ◽  
pp. 312-317 ◽  
Author(s):  
B. Leibiger ◽  
T. Moede ◽  
S. Uhles ◽  
P.-O. Berggren ◽  
I. B. Leibiger
Keyword(s):  
Insulin Secretion ◽  
Gene Transcription ◽  
Insulin Gene ◽  
Current View ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Short Term ◽  
Major Nutrient ◽  
Glucose Metabolites ◽  
Insulin Gene Transcription

Short-term regulation of insulin gene transcription is still a matter of debate. However, an increasing body of evidence shows that insulin gene transcription is affected by signals, such as incretins, glucose metabolites, intracellular Ca2+, and by insulin secreted from pancreatic β-cells, all supporting the concept of an immediate response resulting in insulin gene transcription following food-uptake. The present review aims to summarize the current view on the mechanisms underlying the up-regulation of insulin gene transcription in response to glucose, the major nutrient factor in insulin secretion and biosynthesis.

scholarly journals Transcriptional Regulation of Cyclooxygenase-2 in Response to Proteasome Inhibitors Involves Reactive Oxygen Species-mediated Signaling Pathway and Recruitment of CCAAT/Enhancer-binding Protein δ and CREB-binding Protein

2005 ◽  
Vol 16 (12) ◽  
pp. 5579-5591 ◽  
Author(s):  
Jun-Jie Chen ◽  
Wei-Chien Huang ◽  
Ching-Chow Chen
Keyword(s):  
Reactive Oxygen Species ◽  
Gene Transcription ◽  
Binding Protein ◽  
Proteasome Inhibitors ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Creb Binding Protein ◽  
Enhancer Binding Protein ◽  
Ccaat Enhancer Binding Protein ◽  
Cox 2

Inhibition of ubiquitin-proteasome pathway has been shown to be a promising strategy for the treatment of inflammation and cancer. Here, we show that proteasome inhibitors MG132, PSI-1, and lactacystin induce COX-2 expression via enhancing gene transcription rather than preventing protein degradation in the human alveolar NCI-H292 and A549, and gastric AGS epithelial cells. NF-IL6 and CRE, but not NF-κB elements on the COX-2 promoter were involved in the gene transcription event. The binding of CCAAT/enhancer binding protein (C/EBP)β and C/EBPδ to the CRE and NF-IL6 elements, as well as the recruitment of CBP and the enhancement of histone H3 and H4 acetylation on the COX-2 promoter was enhanced by MG132. However, it did not affect the total protein levels of C/EBPβ and C/EBPδ. MG132-induced DNA-binding activity of C/EBPδ, but not C/EBPβ was regulated by p38, PI3K, Src, and protein kinase C. Small interfering RNA of C/EBPδ suppressed COX-2 expression, further strengthening the role of C/EBPδ in COX-2 gene transcription. In addition, the generation of intracellular reactive oxygen species (ROS) in response to MG132 contributed to the activation of MAPKs and Akt. These findings reveal that the induction of COX-2 transcription induced by proteasome inhibitors requires ROS-dependent protein kinases activation and the subsequent recruitments of C/EBPδ and CBP.

scholarly journals Regulation of Insulin Gene Transcription by ERK1 and ERK2 in Pancreatic β Cells

2003 ◽  
Vol 278 (35) ◽  
pp. 32969-32977 ◽  
Author(s):  
Shih Khoo ◽  
Steven C. Griffen ◽  
Ying Xia ◽  
Richard J. Baer ◽  
Michael S. German ◽  
...  
Keyword(s):  
Gene Transcription ◽  
Insulin Gene ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Insulin Gene Transcription

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 Machine learning algorithms in big data analyses identify determinants of insulin gene transcription

2021 ◽  
Author(s):  
Wilson KM Wong ◽  
Vinod Thorat ◽  
Mugdha V Joglekar ◽  
Charlotte X Dong ◽  
Hugo Lee ◽  
...  
Keyword(s):  
Machine Learning ◽  
Big Data ◽  
Single Cell ◽  
Gene Transcription ◽  
Single Cells ◽  
Machine Learning Algorithms ◽  
Insulin Gene ◽  
Validation Dataset ◽  
Β Cells ◽  
Data Analyses

Machine learning (ML) workflows enable unprejudiced and robust evaluation of complex datasets and are being increasingly sought in analyzing transcriptome-based big datasets. Here, we analysed over 490,000,000 data points to compare 10 different ML algorithms in a large (N=11,652) training dataset of single-cell RNA-sequencing of human pancreatic cells to identify features (genes) associated with the presence or absence of insulin gene transcript(s). Prediction accuracy and sensitivity of models were tested in a separate validation dataset (N=2,913 single-cell transcriptomes) and the efficacy of each ML workflow to accurately identify insulin-producing cells assessed. Overall, Ensemble ML workflows, and in particular, Random Forest ML algorithm delivered high predictive power in a receiver operator characteristic (ROC) curve analysis (AUC=0.83) at the highest sensitivity (0.98) as compared to the other nine algorithms. The top 10 features, (including IAPP, ADCYAP1, LDHA and SST) common to the three Ensemble ML workflows were identified to be localized to human islet-β cells as well as non-β cells and were significantly dysregulated in scRNA-seq datasets from Ire-1αβ-/- mice that demonstrate de-differentiation of pancreatic β-cells as well as in pancreatic single cells from individuals with Type 2 Diabetes. Our findings provide a direct comparison of ML workflows in big data analyses, identify key determinants of insulin transcription and provide workflows for other regulatory analyses to identify/validate novel genes/features of endocrine pancreatic gene transcription.

Sign in / Sign up

Export Citation Format

Share Document