scholarly journals Cytoplasmic polyadenylation-element-binding protein (CPEB)1 and 2 bind to the HIF-1α mRNA 3′-UTR and modulate HIF-1α protein expression

2008 ◽  
Vol 417 (1) ◽  
pp. 235-246 ◽  
Author(s):  
Sonja Hägele ◽  
Uwe Kühn ◽  
Melanie Böning ◽  
Dörthe M. Katschinski
Keyword(s):  
Translational Control ◽  
Binding Protein ◽  
Hypoxia Inducible Factor ◽  
Luciferase Reporter ◽  
Insulin Stimulation ◽  
Luciferase Reporter Gene ◽  
Cytoplasmic Polyadenylation ◽  
Protein Levels ◽  
Hypoxia Inducible Factor 1 ◽  
Element Binding Protein

The heterodimeric HIF (hypoxia-inducible factor)-1 is a transcriptional master regulator of several genes involved in mammalian oxygen homoeostasis. Besides the well described regulation of the HIF-1α subunit via hydroxylation-mediated protein stability in hypoxia, there are several indications of an additional translational control of the HIF-1α mRNA, especially after growth factor stimulation. We identified an interaction of CPEB (cytoplasmic polyadenylation-element-binding protein) 1 and CPEB2 with the 3′-UTR (untranslated region) of HIF-1α mRNA. Overexpression of CPEB1 and CPEB2 affected HIF-1α protein levels mediated by the 3′-UTR of HIF-1α mRNA. Stimulation of neuroblastoma SK-N-MC cells with insulin and thus activation of endogenous CPEBs increased the expression of a luciferase reporter gene fused to the 3′-UTR of HIF-1α as well as endogenous HIF-1α protein levels. This could be abrogated by treating the cells with CPEB1 or CPEB2 siRNAs (short interfering RNAs). Injection of HIF-1α cRNA into Xenopus oocytes verified the elongation of the poly(A)+ (polyadenylated) tail by cytoplasmic polyadenylation. Thus CPEB1 and CPEB2 are involved in the regulation of HIF-1α following insulin stimulation.

scholarly journals Insulin activates the rat sterol-regulatory-element-binding protein 1c (SREBP-1c) promoter through the combinatorial actions of SREBP, LXR, Sp-1 and NF-Y cis-acting elements

2004 ◽  
Vol 385 (1) ◽  
pp. 207-216 ◽  
Author(s):  
Lauren M. CAGEN ◽  
Xiong DENG ◽  
Henry G. WILCOX ◽  
Edwards A. PARK ◽  
Rajendra RAGHOW ◽  
...  
Keyword(s):  
Binding Protein ◽  
Regulatory Element ◽  
Ectopic Expression ◽  
Rat Hepatocytes ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Cis Acting ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

The enhanced synthesis of fatty acids in the liver and adipose tissue in response to insulin is critically dependent on the transcription factor SREBP-1c (sterol-regulatory-element-binding protein 1c). Insulin increases the expression of the SREBP-1c gene in intact liver and in hepatocytes cultured in vitro. To learn the mechanism of this stimulation, we analysed the activation of the rat SREBP-1c promoter and its truncated or mutated congeners driving a luciferase reporter gene in transiently transfected rat hepatocytes. The rat SREBP-1c promoter contains binding sites for LXR (liver X receptor), Sp1, NF-Y (nuclear factor-Y) and SREBP itself. We have found that each of these sites is required for the full stimulatory response of the SREBP-1c promoter to insulin. Mutation of either the putative LXREs (LXR response elements) or the SRE (sterol response element) in the proximal SREBP-1c promoter reduced the stimulatory effect of insulin by about 50%. Insulin and the LXR agonist TO901317 increased the association of SREBP-1 with the SREBP-1c promoter. Ectopic expression of LXRα or SREBP-1c increased activity of the SREBP-1c promoter, and this effect is further enhanced by insulin. The Sp1 and NF-Y sites adjacent to the SRE are also required for full activation of the SREBP-1c promoter by insulin. We propose that the combined actions of the SRE, LXREs, Sp1 and NF-Y elements constitute an insulin-responsive cis-acting unit of the SREBP-1c gene in the liver.

scholarly journals The role of cytosolic polyadenylation element binding protein 2 alternative splicing in hypoxia

2020 ◽  
Author(s):  
Emily M. Mayo ◽  
Shaun C. Stevens ◽  
Anika N. Ali ◽  
Christina J. Moss ◽  
Sean P. Lund ◽  
...  
Keyword(s):  
Chronic Hypoxia ◽  
Binding Protein ◽  
Hypoxia Inducible Factor ◽  
Inhibitory Effect ◽  
Initiation Factor ◽  
Cytoplasmic Polyadenylation ◽  
Translational Repressor ◽  
Hypoxia Exposure ◽  
Element Binding Protein ◽  
Translational Activator

AbstractHIF1 (Hypoxia-inducible Factor 1) is a transcription factor that plays a crucial role in the hypoxia stress response. Its primary function is to return the cell to its homeostatic state following oxygen deprivation. However, chronic hypoxia exposure can cause irreversible physiological changes that can lead to pulmonary hypertension (PH) and the need for therapeutics to ameliorate these conditions is great and unmet. Previous studies in our lab have demonstrated that CPEB2 (cytoplasmic polyadenylation element binding protein 2) is a translational repressor of one of the HIF1 subunits: HIF1α. Our lab demonstrated that the alternatively spliced CPEB2A isoform of CPEB2 is a repressor of translation, while the CPEB2B isoform is a translational activator of HIF1α during hypoxia, suggesting a major regulatory role for CPEB2 AS in the pulmonary hypoxic response. Although it is well established that during hypoxia, HIF1α levels are dramatically upregulated due to a decrease in the degradation of this factor, we propose that during chronic hypoxia, the expression of HIF1α is maintained via a translational mechanism, likely alongside a decrease in proteolytic degradation. In this study we demonstrate that depletion of the CPEB2B splice isoform has an inhibitory effect on the translation of nascent HIF1α protein during chronic hypoxia, but not the acute phase. We further demonstrate that this pathway is dependent on the initiation factor eIF3H. Finally, we show data which indicate that CPEB2A and CPEB2B bind differentially to cytoplasmic polyadenylation element consensus sequences depending on surrounding sequence context. These findings are important, since they provide evidence for potential of CPEB2 to act as a therapeutic target for treating chronic hypoxia-related pulmonary diseases.

Abstract 164: MicroRNA-29c Reduces Serca2 Expression During Myocardial Hypoxia

2012 ◽  
Vol 111 (suppl_1) ◽  
Author(s):  
Keith A MacCannell ◽  
Ralph V Shohet ◽  
Chad B Walton
Keyword(s):  
Hypoxia Inducible Factor ◽  
Cardiac Response ◽  
Luciferase Reporter ◽  
Luciferase Reporter Construct ◽  
Calcium Dependent ◽  
Endoplasmic Reticulum Calcium ◽  
Protein Levels ◽  
Hypoxia Inducible Factor 1 ◽  
A Cell ◽  
Myocardial Hypoxia

The cardiac response to a hypoxic challenge is coordinated by the transcription factor Hypoxia Inducible Factor-1 (HIF-1), which drives the transcription of a large number of genes pertinent to angiogenesis, metabolism, and calcium cycling. Expression of HIF-1alpha that has been mutated to remove oxygen regulation recapitulates many of the changes in gene expression seen in hypoxia. It also results in reversible cardiac dysfunction associated with marked decrease of Sarco-Endoplasmic Reticulum Calcium-Dependent ATP-ase (SERCA2). This decrease in SERCA was more rapid and more substantial than a moderate decrease seen in the mRNA for this protein. In this study, we tested the hypothesis that the decrease in SERCA2 is mediated by the up-regulation of microRNA (miRNA) in the heart. We identified 30 miRNAs that are dysregulated upon induction of oxygen stable HIF1 expression. Three of these have evident binding sites in the 3’ untranslated region of the SERCA2 gene. Transient co-transfection of a mimic molecule for these three miRs with a luciferase reporter construct that includes the 3’ UTR of SERCA2 showed that mi-29c produced a substantial decrease in reporter expression. This effect is abolished by the mutagenesis of the predicted target site within the 3’UTR. Similarly, transfection of this mimic molecule into a cell line that expresses SERCA2 results in a reduction in SERCA2 protein levels. An antagomir to this miR rescues the reduction in SERCA seen with HIF expression. We conclude that miR-29c, is responsible for an important portion of the down-regulation of SERCA2, and thus the contractile dysfunction, seen in hypoxia.

scholarly journals Insulin activates human sterol-regulatory-element-binding protein-1c (SREBP-1c) promoter through SRE motifs

2006 ◽  
Vol 400 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Nicolas Dif ◽  
Vanessa Euthine ◽  
Estelle Gonnet ◽  
Martine Laville ◽  
Hubert Vidal ◽  
...  
Keyword(s):  
Gene Expression ◽  
Binding Protein ◽  
Regulatory Element ◽  
Expression Vectors ◽  
Luciferase Reporter ◽  
Luciferase Reporter Gene ◽  
Direct Role ◽  
Human Skeletal Muscle Cells ◽  
Element Binding Protein ◽  
Sterol Regulatory Element

In the present study, we aimed to decipher the mechanisms involved in the transcriptional effect of insulin on the SREBP-1c specific promoter of the human srebf-1 gene. Using luciferase reporter gene constructs in HEK-293 cells (human embryonic kidney cells), we demonstrated that the full effect of insulin requires the presence of SREs (sterol response elements) in the proximal region of the promoter. Furthermore, insulin increases the binding of SREBP-1 (sterol-regulatory-element-binding protein-1) to this promoter region in chromatin immunoprecipitation assay. We also found that the nuclear receptors LXRs (liver X receptors) strongly activate SREBP-1c gene expression and identified the LXRE (LXR-response element) involved in this effect. However, our results suggested that these LXREs do not play a major role in the response to insulin. Finally, using expression vectors and adenoviruses allowing ectopic overexpressions of the human mature forms of SREBP-1a or SREBP-1c, we demonstrated the direct role of SREBP-1 in the control of SREBP-1c gene expression in human skeletal-muscle cells. Altogether, these results strongly suggest that the SREBP-1 transcription factors are the main mediators of insulin action on SREBP-1c expression in human tissues.

Hypoxia-inducible factor-1 (HIF-1) promotes LDL and VLDL uptake through inducing VLDLR under hypoxia

2011 ◽  
Vol 441 (2) ◽  
pp. 675-683 ◽  
Author(s):  
Guo-Min Shen ◽  
Ying-Ze Zhao ◽  
Ming-Tai Chen ◽  
Feng-Lin Zhang ◽  
Xiao-Ling Liu ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Receptor Gene ◽  
Low Density Lipoprotein ◽  
Hypoxia Inducible Factor ◽  
Density Lipoprotein ◽  
Luciferase Reporter ◽  
Α Subunit ◽  
Vldl Receptor ◽  
Protein Levels ◽  
Hypoxia Inducible Factor 1

Metabolism under hypoxia is significantly different from that under normoxia. It has been well elucidated that HIF-1 (hypoxia-inducible factor-1) plays a central role in regulating glucose metabolism under hypoxia; however, the role of HIF-1 in lipid metabolism has not yet been well addressed. In the present study we demonstrate that HIF-1 promotes LDL (low-density lipoprotein) and VLDL (very-LDL) uptake through regulation of VLDLR (VLDL receptor) gene expression under hypoxia. Increased VLDLR mRNA and protein levels were observed under hypoxic or DFO (deferoxamine mesylate salt) treatment in MCF7, HepG2 and HeLa cells. Using dual-luciferase reporter and ChIP (chromatin immunoprecipitation) assays we confirmed a functional HRE (hypoxia-response element) which is localized at +405 in exon 1 of the VLDLR gene. Knockdown of HIF1A (the α subunit of HIF-1) and VLDLR, but not HIF2A (the α subunit of HIF-2), attenuated hypoxia-induced lipid accumulation through affecting LDL and VLDL uptake. Additionally we also observed a correlation between HIF-1 activity and VLDLR expression in hepatocellular carcinoma specimens. The results of the present study suggest that HIF-1-mediated VLDLR induction influences intracellular lipid accumulation through regulating LDL and VLDL uptake under hypoxia.

lncRNA KCNQ1OT1 promotes the proliferation, migration and invasion of retinoblastoma cells by upregulating HIF-1α via sponging miR-153-3p

2020 ◽  
Vol 68 (8) ◽  
pp. 1349-1356
Author(s):  
Yujin Wang ◽  
Jixiang Wang ◽  
Hongyan Hao ◽  
Xiangxia Luo
Keyword(s):  
Colony Formation ◽  
Rna Binding ◽  
Hypoxia Inducible Factor ◽  
Cell Counting ◽  
Luciferase Reporter ◽  
Migration And Invasion ◽  
Luciferase Reporter Gene ◽  
Tissue Samples ◽  
Qrt Pcr ◽  
Gene Assay

It is reported that lncRNA KCNQ1 opposite strand/antisense transcript 1 (KCNQ1OT1) is oncogenic in many cancers. This work aimed at probing into its expression and biological functions in retinoblastoma (RB) as well as its regulatory effects on miR-153-3p and hypoxia-inducible factor-1α (HIF-1α). In our study, RB samples in pair were collected, and quantitative real-time PCR (qRT-PCR) was employed for examining the expression levels of KCNQ1OT1, miR-153-3p and HIF-1α. KCNQ1OT1 short hairpin RNAs were transfected into SO-Rb50 and HXO-RB44 cell to inhibit the expression of KCNQ1OT1. The proliferative activity, colony formation ability and apoptosis were examined through cell counting kit-8 assay, colony formation assays, Transwell assay and flow cytometry, respectively. qRT-PCR and western blot analysis were used for analyzing the changes of miR-153-3p and HIF-1α induced by KCNQ1OT1. The regulatory relationships between miR-153-3p and KCNQ1OT1, miR-153-3p and HIF-1α were examined by dual luciferase reporter gene assay and RNA-binding protein immunoprecipitation assay. The results of our study showed that KCNQ1OT1 expression was markedly enhanced in RB tissue samples, and KCNQ1OT1 knockdown had an inhibitory effect on the proliferation, migration, invasion and viability of RB cells. There were two validated binding sties between KCNQ1OT1 and miR-153-3p, and KCNQ1OT1 negatively regulated the expression of miR-153-3p in RB cells. HIF-1α was a target gene of miR-153-3p, and could be positively regulated by KCNQ1OT1. In conclusion, our study indicates that KCNQ1OT1 can increase the malignancy of RB cells via regulating miR-153-3p/HIF-1α axis.

Transcriptional regulation of plasminogen activator inhibitor-1 expression by insulin-like growth factor-1 via MAP kinases and hypoxia-inducible factor-1 in HepG2 cells

2005 ◽  
Vol 93 (06) ◽  
pp. 1176-1184 ◽  
Author(s):  
Ulrike Möller ◽  
Stephan Herzig ◽  
Trine Fink ◽  
Vladimir Zachar ◽  
Peter Ebbesen ◽  
...  
Keyword(s):  
Growth Factor ◽  
Hepg2 Cells ◽  
Hypoxia Inducible Factor ◽  
Plasminogen Activator Inhibitor ◽  
Dominant Negative ◽  
Plasminogen Activator Inhibitor 1 ◽  
Protein Levels ◽  
Hypoxia Inducible Factor 1 ◽  
Activator Inhibitor ◽  
Pai 1

SummaryInsulin-like growth factor 1 (IGF-1) and plasminogen activator inhibitor-1 (PAI-1) appear to play a crucial role in a number of processes associated with growth and tissue remodelling. IGF-1 was shown to enhance PAI-1 expression in primary hepatocytes and HepG2 hepatoma cells, but the molecular mechanisms underlying this effect have not been fully elucidated. In this study, we investigated the transcriptional mechanism and the signaling pathway by which IGF-1 mediates induction of PAI-1 expression in HepG2 cells. By using human PAI-1 promoter reporter gene assays we found that mutation of the hypoxia responsive element (HRE), which could bind hypoxia-inducible factor-1 (HIF-1), nearly abolished the induction by IGF-1. We found that IGF-1-induced up-regulation of PAI-1 expression was associated with activation of HIF-1α. Furthermore, IGF-1 enhanced HIF-1α protein levels and HIF-1 DNA-binding to each HRE, E4 and E5 as shown by EMSA. Mutation of the E-boxes, E4 and E5, did not affect the IGF-1-dependent induction of PAI-1 promoter constructs under normoxia but abolished the effect of IGF-1 under hypoxia. Inhibition of either the PI3K by LY294002 or ERK1/2 by U0126 reduced HIF-1α protein levels while both inhibitors together completely abolished the IGF-1 effect on HIF-1α. Remarkably, transfection of HepG2 cells with vectors expressing a dominant-negative PDK1 or the PKB inhibitor, TRB3, did not influence while dominant-negative Raf inhibited the IGF-1 effect on HIF-1α. Thus, IGF-1 activates human PAI-1 gene expression through activation of the PI3-kinase and ERK1/2 via HIF-1α.

Corrigendum to: Cytoplasmic polyadenylation element binding protein 2 (CPEB2) is required for tight-junction assembly for establishment of porcine trophectoderm epithelium

2019 ◽  
Vol 31 (3) ◽  
pp. 632
Author(s):  
Jeongwoo Kwon ◽  
Shuha Park ◽  
Min-Jung Seong ◽  
Inchul Choi ◽  
Nam-Hyung Kim
Keyword(s):  
Tight Junction ◽  
Mrna Stability ◽  
Rna Binding ◽  
Binding Protein ◽  
Mrna Translation ◽  
Coxsackie Virus ◽  
Cytoplasmic Polyadenylation ◽  
Apical Cell Membrane ◽  
Junction Protein ◽  
Element Binding Protein

Cytoplasmic polyadenylation element binding protein (CPEB) is an RNA-binding protein that promotes elongation of poly(A) tails and regulates mRNA translation. CPEB depletion in mammary epithelium is known to disrupt tight-junction (TJ) assembly via mislocalisation of tight junction protein 1 (TJP1), but the role of CPEB in the biological functions associated with TJs has not yet been studied. The objective of this study was to investigate the roles of CPEB2 during porcine parthenote development. CPEB2 was detected in both the nuclei and apical cytoplasm at the 4- and 8-cell stages and was localised to cell–cell contact after the initiation of the morula stage. Its depletion led to retarded blastocyst formation caused by impaired TJ assembly. Moreover, transcription of TJ-associated genes, including TJP1, Coxsackie virus and adenovirus receptor (CXADR) and occludin (OCLN), was not affected, but the corresponding proteins were not properly localised at the apical cell membrane in morulae, suggesting that CPEB2 confers mRNA stability or determines subcellular localisation for translation. Remarkably reduced relative levels of TJP1 transcripts bearing the 3′-untranslated region were noted, indicating that CPEB2 mediates TJP1 mRNA stability. In conclusion, our findings demonstrate that because of its regulation of TJP1, CPEB2 is required for TJ assembly during porcine blastocyst development.

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