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.

scholarly journals Sagunja-Tang Improves Lipid Related Disease in a Postmenopausal Rat Model and HepG2 Cells

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Hiroe Go ◽  
Jin Ah Ryuk ◽  
Hye Won Lee ◽  
In Sil Park ◽  
Ki-Jung Kil ◽  
...  
Keyword(s):  
Lipid Accumulation ◽  
Hepg2 Cells ◽  
Cholesterol Synthesis ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Low Density ◽  
Protein Levels ◽  
Related Disease

The present study was conducted to investigate the effect of Sagunja-tang on the lipid related disease in a rat model of menopausal hyperlipidemia and lipid accumulation in methyl-β-cyclodextrin-induced HepG2 cells. Inin vivostudy using menopausal hyperlipidemia rats, Sagunja-tang reduced retroperitoneal and perirenal fat, serum lipids, atherogenic index, cardiac risk factor, media thickness, and nonalcoholic steatohepatitis score, when compared to menopausal hyperlipidemia control rats. In HepG2 cells, Sagunja-tang significantly decreased the lipid accumulation, total cholesterol levels, and low-density/very-low-density lipoprotein levels. Moreover, Sagunja-tang reversed the methyl-β-cyclodextrin-induced decrease in the protein levels of critical molecule involved in cholesterol synthesis, sterol regulatory element binding protein-2, and low-density lipoprotein receptor and inhibited protein levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase as well as activity. Phosphorylation level of AMP-activated protein kinase was stimulated by Sagunja-tang. These results suggest that Sagunja-tang has effect on inhibiting hepatic lipid accumulation through regulation of cholesterol synthesis and AMPK activityin vitro. These observations support the idea that Sagunja-tang is bioavailable bothin vivoandin vitroand could be developed as a preventive and therapeutic agent of hyperlipidemia in postmenopausal females.

Oxidized low-density lipoprotein (oxLDL) triggers hypoxia-inducible factor-1α (HIF-1α) accumulation via redox-dependent mechanisms

Blood ◽  
2003 ◽  
Vol 101 (12) ◽  
pp. 4847-4849 ◽  
Author(s):  
Vladimir A. Shatrov ◽  
Vadim V. Sumbayev ◽  
Jie Zhou ◽  
Bernhard Brüne
Keyword(s):  
Reporter Gene ◽  
Low Density Lipoprotein ◽  
Hypoxia Inducible Factor ◽  
Density Lipoprotein ◽  
Luciferase Reporter ◽  
Low Density ◽  
Mrna Levels ◽  
Oxidized Low Density Lipoprotein ◽  
Human Macrophages ◽  
Hypoxia Inducible Factor 1Α

Abstract Oxidized low-density lipoprotein (oxLDL) and macrophages play a central role in atherosclerosis. Here, we obtained evidence that oxLDL induced hypoxia-inducible factor-1α (HIF-1α) protein accumulation in human macrophages (Mono-Mac-6) under normoxia. HIF-1α accumulation was attenuated by pretreatment with the antioxidant N-acetyl-L-cysteine (NAC), the nitric oxide (NO) donor S-nitrosoglutathione (GSNO), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors such as diphenyleniodonium (DPI) or 4-(2-aminoethyl)-benzenesulfonyl fluoride (AEBSF), thus implicating the contribution of oxLDL-generated reactive oxygen species (ROS). Whereas oxLDL did not modulate HIF-1α mRNA levels, experiments with cycloheximide pointed to a translational mechanism in oxLDL action. HIF-1–dependent luciferase reporter gene analysis underscored HIF-1 transactivation. Our results indicate that oxLDL induced HIF-1α accumulation and HIF-1–dependent reporter gene activation in human macrophages via a redox-mediated pathway. This finding may suggest a role of HIF-1 in atherosclerosis and oxLDL-induced pathogenesis.

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.

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 LncRNA TP73-AS1 promotes oxidized low-density lipoprotein-induced apoptosis of endothelial cells in atherosclerosis by targeting the miR-654-3p/AKT3 axis

2021 ◽  
Vol 26 (1) ◽  
Author(s):  
Jia Ni ◽  
Zhen Huang ◽  
Dan Wang
Keyword(s):  
Endothelial Cells ◽  
Cell Model ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Luciferase Reporter ◽  
Low Density ◽  
Oxidized Low Density Lipoprotein ◽  
Protein Levels ◽  
Cell Functions ◽  
Induced Apoptosis

Abstract Background Although lncRNA TP73-AS1 has been shown to play important roles in various human diseases, its function in atherosclerosis (AS) remains unclear. Methods Human aortic endothelial cells (HAECs) were treated with 50 μg/ml oxidized low-density lipoprotein (ox-LDL) to establish an atherosclerotic cell model. The expression of TP73-AS1, miR-654-3p and AKT3 was detected by qRT-PCR. Cell functions were evaluated CCK-8 assay and flow cytometry. The protein levels of apoptosis-related proteins were evaluated by western blot. The binding relationship among TP73-AS1, miR-654-3p and AKT3 was determined by bioinformatics analysis and luciferase reporter assay. Results TP73-AS1 was upregulated and miR-654-3p was downregulated in ox-LDL treated HAECs. TP73-AS1 silencing and miR-654-3p mimics decreased the viability and inhibited apoptosis of ox-LDL treated HAECs, decreased the expression levels of c-caspase-9, c-caspase-3 and Bax, and increased Bcl-2 expression. In addition, miR-654-3p inhibitor significantly reversed the inhibitory effects of si-TP73-AS1 on cell viability and apoptosis. TP73-AS1 could positively regulate AKT3 through directly sponging miR-654-3p. Conclusion TP73-AS1 promoted apoptosis of ox-LDL stimulated endothelial cells by targeting the miR-654-3p/AKT3 axis, suggesting that TP73-AS1 might be a potential target for AS treatment.

scholarly journals A long hypoxia-inducible factor 3 isoform 2 is a transcription activator that regulates erythropoietin

2019 ◽  
Vol 77 (18) ◽  
pp. 3627-3642 ◽  
Author(s):  
Jussi-Pekka Tolonen ◽  
Minna Heikkilä ◽  
Marjo Malinen ◽  
Hang-Mao Lee ◽  
Jorma J. Palvimo ◽  
...  
Keyword(s):  
Target Genes ◽  
Hypoxia Inducible Factor ◽  
Negative Regulator ◽  
Luciferase Reporter ◽  
Transcription Activator ◽  
Promoter Regions ◽  
Α Subunit ◽  
Hypoxia Response ◽  
Protein Levels ◽  
Oxygen Homeostasis

AbstractHypoxia-inducible factor (HIF), an αβ dimer, is the master regulator of oxygen homeostasis with hundreds of hypoxia-inducible target genes. Three HIF isoforms differing in the oxygen-sensitive α subunit exist in vertebrates. While HIF-1 and HIF-2 are known transcription activators, HIF-3 has been considered a negative regulator of the hypoxia response pathway. However, the human HIF3A mRNA is subject to complex alternative splicing. It was recently shown that the long HIF-3α variants can form αβ dimers that possess transactivation capacity. Here, we show that overexpression of the long HIF-3α2 variant induces the expression of a subset of genes, including the erythropoietin (EPO) gene, while simultaneous downregulation of all HIF-3α variants by siRNA targeting a shared HIF3A region leads to downregulation of EPO and additional genes. EPO mRNA and protein levels correlated with HIF3A silencing and HIF-3α2 overexpression. Chromatin immunoprecipitation analyses showed that HIF-3α2 binding associated with canonical hypoxia response elements in the promoter regions of EPO. Luciferase reporter assays showed that the identified HIF-3α2 chromatin-binding regions were sufficient to promote transcription by all three HIF-α isoforms. Based on these data, HIF-3α2 is a transcription activator that directly regulates EPO expression.

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