scholarly journals The Liver X Receptor Ligand T0901317 Down-regulatesAPOA5Gene Expression through Activation of SREBP-1c

2004 ◽  
Vol 279 (44) ◽  
pp. 45462-45469 ◽  
Author(s):  
Heidelinde Jakel ◽  
Maxime Nowak ◽  
Emanuelle Moitrot ◽  
Hélène Dehondt ◽  
Dean W. Hum ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Regulatory Element ◽  
Hepatoma Cell ◽  
Active Form ◽  
Liver X Receptor ◽  
Plasma Triglyceride ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Down Regulation

Alterations in the expression of the recently discovered apolipoprotein A5 gene strongly affect plasma triglyceride levels. In this study, we investigated the contribution ofAPOA5to the liver X receptor (LXR) ligand-mediated effect on plasma triglyceride levels. Following treatment with the LXR ligand T0901317, we found thatAPOA5mRNA levels were decreased in hepatoma cell lines. The observation that no down-regulation ofAPOA5promoter activity was obtained by LXR-retinoid X receptor (RXR) co-transfection prompted us to explore the possible involvement of the known LXR target gene SREBP-1c (sterol regulatory element-binding protein 1c). In fact, we found that co-transfection with the active form of SREBP-1c down-regulatedAPOA5promoter activity in a dose-dependent manner. We then scanned the humanAPOA5promoter sequence and identified two putative E-box elements that were able to bind specifically SREBP-1c in gel-shift assays and were shown to be functional by mutation analysis. Subsequent suppression of SREBP-1 mRNA through small interfering RNA interference abolished the decrease ofAPOA5mRNA in response to T0901317. Finally, administration of T0901317 tohAPOA5transgenic mice revealed a significant decrease ofAPOA5mRNA in liver tissue and circulating apolipoprotein AV protein in plasma, confirming that the described down-regulation also occursin vivo. Taken together, our results demonstrate thatAPOA5gene expression is regulated by the LXR ligand T0901317 in a negative manner through SREBP-1c. These findings may provide a new mechanism responsible for the elevation of plasma triglyceride levels by LXR ligands and support the development of selective LXR agonists, not affecting SREBP-1c, as beneficial modulators of lipid metabolism.

scholarly journals Estrogen Up-Regulates Hepatic Expression of Suppressors of Cytokine Signaling-2 and -3 in Vivo and in Vitro

Endocrinology ◽  
2004 ◽  
Vol 145 (12) ◽  
pp. 5525-5531 ◽  
Author(s):  
Gary M. Leong ◽  
Sofia Moverare ◽  
Jesena Brce ◽  
Nathan Doyle ◽  
Klara Sjögren ◽  
...  
Keyword(s):  
Promoter Activity ◽  
Hepatoma Cells ◽  
Cytokine Signaling ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Wild Type ◽  
Hepatic Expression ◽  
Suppressors Of Cytokine Signaling

Abstract Suppressors of cytokine signaling (SOCS) are important negative regulators of cytokine action. We recently reported that estrogen stimulates SOCS-2 expression and inhibits GH signaling in kidney cells. The effects of estrogen on SOCS expression in other tissues are unclear. The aim of this study was to investigate in vivo and in vitro whether estrogen affected SOCS expression in the liver, a major target organ of GH. The in vivo hepatic effects of estrogen on ovariectomized mice lacking estrogen receptor (ER)-α, ERβ, or both and their wild-type littermates were examined by DNA microarray analysis. In vitro, the effects of estrogen on SOCS expression in human hepatoma cells were examined by reverse transcription quantitative PCR. Long-term (3 wk) estrogen treatment induced a 2- to 3-fold increase in hepatic expression of SOCS-2 and -3 in wild-type and ERβ knockout mice but not in those lacking ERα or both ER subtypes. Short-term treatment (at 24 h) increased the mRNA level of SOCS-3 but not SOCS-2. In cultured hepatoma cells, estrogen increased SOCS-2 and -3 mRNA levels by 2-fold in a time- and dose-dependent manner (P < 0.05). Estrogen induced murine SOCS-3 promoter activity by 2-fold (P < 0.05) in constructs containing a region between nucleotides −1862 and −855. Moreover, estrogen and GH had additive effects on the SOCS-3 promoter activity. In summary, estrogen, via ERα, up-regulated hepatic expression of SOCS-2 and -3, probably through transcriptional activation. This indicates a novel mechanism of estrogen regulation of cytokine action.

scholarly journals Glucolipotoxicity and GLP-1 secretion

2021 ◽  
Vol 9 (1) ◽  
pp. e001905
Author(s):  
Jung-Hee Hong ◽  
Dae-Hee Kim ◽  
Moon-Kyu Lee
Keyword(s):  
Glucose Transporter ◽  
Cell Function ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Gene Expressions ◽  
Simultaneous Treatment ◽  
L Cells ◽  
Triglyceride Accumulation

IntroductionThe concept of glucolipotoxicity refers to the combined, deleterious effects of elevated glucose and/or fatty acid levels.Research design and methodsTo investigate the effects of chronic glucolipotoxicity on glucagon-like peptide-1-(7-36) amide (GLP-1) secretion, we generated glucolipotoxic conditions in human NCI-H716 enteroendocrine cells using either 5 or 25 mM glucose with or without 500 µM palmitate for 72 hours. For in vivo study, we have established a chronic nutrient infusion model in the rat. Serial blood samples were collected for 2 hours after the consumption of a mixed meal to evaluate insulin sensitivity and β-cell function.ResultsChronic glucolipotoxic conditions decreased GLP-1 secretion and the expressions of pCREB, pGSK3β, β-catenin, and TCF7L2 in NCI-H716 cells. Glucolipotoxicity conditions reduced glucose transporter expression, glucose uptake, and nicotinamide-adenine dinucleotide phosphate (NADPH) levels in L-cells, and increased triglyceride accumulation. In contrast, PPARα and ATP levels were reduced, which correlated well with decreased levels of SUR1 and Kir6.2, cAMP contents and expressions of pCAMK2, EPAC and PKA. We also observed an increase in reactive oxygen species production, UCP2 expression and Complex I activity. Simultaneous treatment with insulin restored the GLP-1 secretion. Glucolipotoxic conditions decreased insulin secretion in a time-dependent manner in INS-1 cells, which was recovered with exendin-4 cotreatment. Glucose and SMOFlipid infusion for 6 hours decreased GLP-1 secretion and proglucagon mRNA levels as well as impaired the glucose tolerance, insulin and C-peptide secretion in rats.ConclusionThese results provide evidence for the first time that glucolipotoxicity could affect GLP-1 secretion through changes in glucose and lipid metabolism, gene expressions, and proglucagon biosynthesis and suggest the interrelationship between glucolipotoxicities of L-cells and β-cells which develops earlier than that of L-cells.

scholarly journals Pyrrolizidine Alkaloids Induce Cell Death in Human HepaRG Cells in a Structure-Dependent Manner

2020 ◽  
Vol 22 (1) ◽  
pp. 202
Author(s):  
Josephin Glück ◽  
Julia Waizenegger ◽  
Albert Braeuning ◽  
Stefanie Hessel-Pras
Keyword(s):  
Cell Death ◽  
Cell Viability ◽  
Pyrrolizidine Alkaloids ◽  
Defense Mechanism ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Dependent Manner ◽  
Human Hepatoma Cell

Pyrrolizidine alkaloids (PAs) are a group of secondary metabolites produced in various plant species as a defense mechanism against herbivores. PAs consist of a necine base, which is esterified with one or two necine acids. Humans are exposed to PAs by consumption of contaminated food. PA intoxication in humans causes acute and chronic hepatotoxicity. It is considered that enzymatic PA toxification in hepatocytes is structure-dependent. In this study, we aimed to elucidate the induction of PA-induced cell death associated with apoptosis activation. Therefore, 22 structurally different PAs were analyzed concerning the disturbance of cell viability in the metabolically competent human hepatoma cell line HepaRG. The chosen PAs represent the main necine base structures and the different esterification types. Open-chained and cyclic heliotridine- and retronecine-type diesters induced strong cytotoxic effects, while treatment of HepaRG with monoesters did not affect cell viability. For more detailed investigation of apoptosis induction, comprising caspase activation and gene expression analysis, 14 PA representatives were selected. The proapoptotic effects were in line with the potency observed in cell viability studies. In vitro data point towards a strong structure–activity relationship whose effectiveness needs to be investigated in vivo and can then be the basis for a structure-associated risk assessment.

scholarly journals Tumor-Stroma Crosstalk Enhances REG3A Expressions that Drive the Progression of Hepatocellular Carcinoma

2020 ◽  
Vol 21 (2) ◽  
pp. 472 ◽  
Author(s):  
Yuri Cho ◽  
Min Ji Park ◽  
Koeun Kim ◽  
Jae-Young Park ◽  
Jihye Kim ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Microarray Analysis ◽  
Cdna Microarray ◽  
Tumor Stroma ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Cdna Microarray Analysis ◽  
Hcc Cells

Abstract: Background: Crosstalk between tumors and their microenvironment plays a crucial role in the progression of hepatocellular carcinoma (HCC). However, there is little existing information about the key signaling molecule that modulates tumor-stroma crosstalk. Methods: Complementary DNA (cDNA) microarray analysis was performed to identify the key molecule in tumor-stroma crosstalk. Subcutaneous xenograft in vivo murine model, immunoblotting, immunofluorescence, and real-time polymerase chain reaction using HCC cells and tissues were performed. Results: The key molecule, regenerating gene protein-3A (REG3A), was most significantly enhanced when coculturing HCC cells and activated human hepatic stellate cells (HSCs) (+8.2 log) compared with monoculturing HCC cells using cDNA microarray analysis. Downregulation of REG3A using small interfering RNA significantly decreased the proliferation of HSC-cocultured HCC cells in vitro and in vivo, and enhanced deoxycholic acid-induced HCC cell apoptosis. Crosstalk-induced REG3A upregulation was modulated by platelet-derived growth factor ββ (PDGF-ββ) in p42/44-dependent manner. REG3A mRNA levels in human HCC tissues were upregulated 1.8-fold compared with non-tumor tissues and positively correlated with PDGF-ββ levels. Conclusions: REG3A/p42/44 pathway/PDGF-ββ signaling plays a significant role in hepatocarcinogenesis via tumor-stroma crosstalk. Targeting REG3A is a potential novel therapeutic target for the management of HCCs by inhibiting crosstalk between HCC cells and HSCs.

Royal Jelly Reduces Melanin Synthesis Through Down-Regulation of Tyrosinase Expression

2011 ◽  
Vol 39 (06) ◽  
pp. 1253-1260 ◽  
Author(s):  
Sang Mi Han ◽  
Joo Hong Yeo ◽  
Yoon Hee Cho ◽  
Sok Cheon Pak
Keyword(s):  
Royal Jelly ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Melanin Synthesis ◽  
Mrna Transcription ◽  
Down Regulation ◽  
Melanin Biosynthesis ◽  
Skin Whitening ◽  
Key Enzyme ◽  
Dose Dependent

For cosmetic reasons, the demand for effective and safe skin-whitening agents is high. Since the key enzyme in the melanin synthetic pathway is tyrosinase, many depigmenting agents in the treatment of hyperpigmentation act as tyrosinase inhibitors. In this study, we have investigated the hypo-pigmentary mechanism of royal jelly in a mouse melanocyte cell line, B16F1. Treatment of B16F1 cells with royal jelly markedly inhibited melanin biosynthesis in a dose-dependent manner. Decreased melanin content occurred through the decrease of tyrosinase activity. The mRNA levels of tyrosinase were also reduced by royal jelly. These results suggest that royal jelly reduces melanin synthesis by down-regulation of tyrosinase mRNA transcription and serves as a new candidate in the design of new skin-whitening or therapeutic agents.

scholarly journals In vivo and in vitro regulation of erythropoietin mRNA: measurement by competitive polymerase chain reaction

Blood ◽  
1993 ◽  
Vol 81 (3) ◽  
pp. 617-623 ◽  
Author(s):  
J Fandrey ◽  
HF Bunn
Keyword(s):  
Polymerase Chain Reaction ◽  
Hepatoma Cell ◽  
Hepatoma Cell Line ◽  
Mrna Levels ◽  
Chain Reaction ◽  
Human Hepatoma Cell ◽  
Competitive Polymerase Chain Reaction ◽  
Polymerase Chain

Abstract The regulation of erythropoietin (Epo) production was investigated by competitive polymerase chain reaction, a highly sensitive and accurate means of measuring Epo mRNA levels. Co-amplification of the test sample with added mutant Epo cDNA template corrects for variability in the efficiency of amplification. Epo mRNA levels were determined in tissues of normal rats and in animals with varying degrees of anemia. Reduction of the hematocrit level from 0.40 to 0.15–0.20 resulted in a 300-fold increase in kidney Epo mRNA, which comprised 80% of the total Epo mRNA versus 20% from the liver. In contrast, very low levels detected in lung and spleen were not significantly increased by anemia. The human hepatoma cell line, Hep3B, secretes high levels of Epo in response to hypoxia. This regulation is, to a large extent, transcriptional. When Hep3B cells were incubated in the presence of decreasing O2 tension from 160 to 7 mm Hg, there was a monotonic increase in Epo mRNA to 50 to 100 times the normoxic level. Hyperoxia did not suppress basal expression. When cells were incubated at a PO2 of 7 mm Hg, induction of Epo mRNA was first noted at 30 minutes and was maximal at 5 to 6 hours. After Epo mRNA was boosted by a 4-hour hypoxic incubation, cells were then exposed to normoxia, which shut off further transcription of the Epo gene. The decay of Epo mRNA levels closely followed first order kinetics with a half-life of 2 hours, an effective measurement of message stability.

scholarly journals Suppression of the GnRH Pulse Generator by Neurokinin B Involves a κ-Opioid Receptor-Dependent Mechanism

Endocrinology ◽  
2012 ◽  
Vol 153 (10) ◽  
pp. 4894-4904 ◽  
Author(s):  
P. Grachev ◽  
X. F. Li ◽  
J. S. Kinsey-Jones ◽  
A. L. di Domenico ◽  
R. P. Millar ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Pulse Generator ◽  
Pulse Frequency ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Neurokinin B ◽  
Kndy Neurons ◽  
Lh Secretion ◽  
Dose Dependent

Abstract Neurokinin B (NKB) and its receptor (NK3R) are coexpressed with kisspeptin, Dynorphin A (Dyn), and their receptors [G-protein-coupled receptor-54 (GPR54)] and κ-opioid receptor (KOR), respectively] within kisspeptin/NKB/Dyn (KNDy) neurons in the hypothalamic arcuate nucleus (ARC), the proposed site of the GnRH pulse generator. Much previous research has employed intracerebroventricular (icv) administration of KNDy agonists and antagonists to address the functions of KNDy neurons. We performed a series of in vivo neuropharmacological experiments aiming to determine the role of NKB/NK3R signaling in modulating the GnRH pulse generator and elucidate the interaction between KNDy neuropeptide signaling systems, targeting our interventions to ARC KNDy neurons. First, we investigated the effect of intra-ARC administration of the selective NK3R agonist, senktide, on pulsatile LH secretion using a frequent automated serial sampling method to obtain blood samples from freely moving ovariectomized 17β-estradiol-replaced rats. Our results show that senktide suppresses LH pulses in a dose-dependent manner. Intra-ARC administration of U50488, a selective KOR agonist, also caused a dose-dependent, albeit more modest, decrease in LH pulse frequency. Thus we tested the hypothesis that Dyn/KOR signaling localized to the ARC mediates the senktide-induced suppression of the LH pulse by profiling pulsatile LH secretion in response to senktide in rats pretreated with nor-binaltorphimine, a selective KOR antagonist. We show that nor-binaltorphimine blocks the senktide-induced suppression of pulsatile LH secretion but does not affect LH pulse frequency per se. In order to address the effects of acute activation of ARC NK3R, we quantified (using quantitative RT-PCR) changes in mRNA levels of KNDy-associated genes in hypothalamic micropunches following intra-ARC administration of senktide. Senktide down-regulated expression of genes encoding GnRH and GPR54 (GNRH1 and Kiss1r, respectively), but did not affect the expression of Kiss1 (which encodes kisspeptin). We conclude that NKB suppresses the GnRH pulse generator in a KOR-dependent fashion and regulates gene expression in GnRH neurons.

Effect of cyclosporin A treatment on the in vivo regulation of type I MHC gene expression

2004 ◽  
Vol 97 (2) ◽  
pp. 475-483 ◽  
Author(s):  
Julia M. Giger ◽  
Fadia Haddad ◽  
Anqi X. Qin ◽  
Kenneth M. Baldwin
Keyword(s):  
Cyclosporin A ◽  
Promoter Activity ◽  
Pcr Analysis ◽  
Type I ◽  
Mrna Levels ◽  
Activated T Cells ◽  
Obvious Effect ◽  
Enhancer Region ◽  
Muscle Gene

Rat soleus muscle consists predominantly of slow type I fibers. We have shown previously through deletion analysis that the highest level of reporter activity that we measure when injecting type I myosin heavy chain (MHC) promoter (MHC1)-linked luciferase plasmid into soleus muscles depends on the presence of a 550-bp upstream enhancer (3,450–2,900) region of the promoter. Because the calcineurin-nuclear factor of activated T cells (NFAT) pathway has been implicated in the regulation of the slow muscle gene program, particularly the MHC1 isoform, and the MHC1 promoter contains several putative NFAT sites, we examined via deletion and mutation analyses whether this pathway is involved in the regulation of promoter activity in soleus. Nine days of treatment with the calcineurin inhibitor cyclosporin A (CsA) caused a significant decrease in activity of the −3,500- and −3,450-bp promoters compared with vehicle-treated rats. Truncation of the promoter to −2,900 bp or smaller reduced the activity and also eliminated the CsA responsiveness, thus implying that the enhancer region is required for CsA responsiveness. Surprisingly, mutating the two NFAT elements within the enhancer region had no obvious effect on promoter activity. CsA treatment resulted in an increase in the mRNA levels of fast-type IIa and IIx MHC isoforms, but RT-PCR analysis of MHC1 pre-mRNA and mature mRNA expression in soleus muscles revealed no differences between vehicle- and CsA-treated rats. Although CsA affects the activity of the MHC1 promoter, it appears that its effect is not through direct binding of NFAT to sites on the promoter.

scholarly journals Long-Range Transcriptional Control of theIl2Gene by an Intergenic Enhancer

2015 ◽  
Vol 35 (22) ◽  
pp. 3880-3891 ◽  
Author(s):  
Parul Mehra ◽  
Andrew D. Wells
Keyword(s):  
Autoimmune Disease ◽  
Long Range ◽  
Transcriptional Control ◽  
Regulatory Element ◽  
Interleukin 2 ◽  
Regulatory Region ◽  
Dependent Manner ◽  
Regulatory Architecture

Interleukin-2 (IL-2) is a potent cytokine with roles in both immunity and tolerance. Genetic studies in humans and mice demonstrate a role forIl2in autoimmune disease susceptibility, and for decades the proximalIl2upstream regulatory region has served as a paradigm of tissue-specific, inducible gene regulation. In this study, we have identified a novel long-range enhancer of theIl2gene located 83 kb upstream of the transcription start site. This element can potently enhanceIl2transcription in recombinant reporter assaysin vitro, and the native region undergoes chromatin remodeling, transcribes a bidirectional enhancer RNA, and loops to physically interact with theIl2genein vivoin a CD28-dependent manner in CD4+T cells. Thiscisregulatory element is evolutionarily conserved and is situated near a human single-nucleotide polymorphism (SNP) associated with multiple autoimmune disorders. These results indicate that the regulatory architecture of theIl2locus is more complex than previously appreciated and suggest a novel molecular basis for the genetic association ofIl2polymorphism with autoimmune disease.

scholarly journals Effects on Liver Lipid Metabolism of the Naturally Occurring Dietary Flavone Luteolin-7-glucoside

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Carla Sá ◽  
Ana Rita Oliveira ◽  
Cátia Machado ◽  
Marisa Azevedo ◽  
Cristina Pereira-Wilson
Keyword(s):  
Lipid Metabolism ◽  
Fatty Acid Synthase ◽  
Molecular Mechanisms ◽  
Metabolic Diseases ◽  
Regulatory Element ◽  
Lipid Lowering ◽  
Whole Body ◽  
Mrna Levels ◽  
Dependent Manner ◽  
Hepatic Expression

Disruptions in whole-body lipid metabolism can lead to the onset of several pathologies such as nonalcoholic fatty liver disease (NAFLD) and cardiovascular diseases (CVDs). The present study aimed at elucidating the molecular mechanisms behind the lipid-lowering effects of the flavone luteolin-7-glucoside (L7G) which we previously showed to improve plasma lipid profile in rats. L7G is abundant in plant foods of Mediterranean diet such as aromatic plants used as herbs. Results show that dietary supplementation with L7G for one week induced the expression of peroxisome proliferator-activated receptor-alpha (PPAR-α) and of its target gene carnitine palmitoyl transferase 1 (CPT-1) in rat liver. L7G showed a tendency to decrease the hepatic expression of sterol regulatory element-binding protein-1 (SREBP-1), without affecting fatty acid synthase (FAS) protein levels. Although SREBP-2 and LDLr mRNA levels did not change, the expression of HMG CoA reductase (HMGCR) was significantly repressed by L7G. L7G also inhibited this enzyme’sin vitroactivity in a dose dependent manner, but only at high and not physiologically relevant concentrations. These results add new evidence that the flavone luteolin-7-glucoside may help in preventing metabolic diseases and clarify the mechanisms underlying the beneficial health effects of diets rich in fruits and vegetables.

Sign in / Sign up

Export Citation Format

Share Document