scholarly journals Regulation of Carbohydrate Metabolism by the Farnesoid X Receptor

Endocrinology ◽  
2005 ◽  
Vol 146 (3) ◽  
pp. 984-991 ◽  
Author(s):  
Keith R. Stayrook ◽  
Kelli S. Bramlett ◽  
Rajesh S. Savkur ◽  
James Ficorilli ◽  
Todd Cook ◽  
...  
Keyword(s):  
Gene Expression ◽  
Carbohydrate Metabolism ◽  
Hepatoma Cell ◽  
Human Hepatocytes ◽  
Farnesoid X Receptor ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Hepatoma Cell Lines ◽  
Rat Hepatoma ◽  
Stimulation Of

The farnesoid X receptor (FXR; NR1H4) is a nuclear hormone receptor that functions as the bile acid receptor. In addition to the critical role FXR plays in bile acid metabolism and transport, it regulates a variety of genes important in lipoprotein metabolism. We demonstrate that FXR also plays a role in carbohydrate metabolism via regulation of phosphoenolpyruvate carboxykinase (PEPCK) gene expression. Treatment of either H4IIE or MH1C1 rat hepatoma cell lines as well as primary rat or human hepatocytes with FXR agonists led to stimulation of PEPCK mRNA expression to levels comparable to those obtained with glucocorticoid receptor agonists. We examined the physiological significance of FXR agonist-induced enhancement of PEPCK expression in primary rat hepatocytes. In addition to inducing PEPCK expression in primary hepatocytes, FXR agonists stimulated glucose output to levels comparable to those observed with a glucocorticoid receptor agonist. Consistent with these observations, treatment of C57BL6 mice with GW4064 significantly increased hepatic PEPCK expression. Activation of FXR initiated a cascade involving induction of peroxisome proliferator-activated receptor α and TRB3 expression that is consistent with stimulation of PEPCK gene expression via interference with a pathway that may involve Akt-dependent phosphorylation of Forkhead/winged helix transcription factor (FOXO1). The FXR-peroxisome proliferator-activated receptor α-TRB3 pathway was conserved in rat hepatoma cell lines, mice, as well as primary human hepatocytes. Thus, in addition to its role in the regulation of lipid metabolism, FXR regulates carbohydrate metabolism.

scholarly journals AS-30D hepatoma as a model to study on insulin resistance in vitro.

2013 ◽  
Vol 60 (4) ◽  
Author(s):  
Katarzyna Wierzbicka-Bregier ◽  
Wojciech Brutkowski ◽  
Anna Borkowska ◽  
Krzysztof Milewski ◽  
Krzysztof Zabłocki
Keyword(s):  
Insulin Resistance ◽  
Cell Lines ◽  
Hepatoma Cell ◽  
Cellular Level ◽  
Ros Generation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Hepatoma Cell Lines ◽  
Kinase Phosphorylation

Studies on insulin resistance of liver cells are often performed with the use of various hepatoma cell lines. Such an approach allows investigating selected biochemical pathways at the cellular level. However, possible modifications of metabolic processes due to the neoplastic nature of such cells must be considered. Expanding the diversity of hepatoma cell lines used in metabolic studies could deliver new data for comparison with those obtained for other cell lines and should reduce the risk of misleading conclusions. In this study rat hepatoma AS-30D cells were tested as a potential model for studies on palmitate-induced insulin resistance. It was found that insulin-induced Akt kinase phosphorylation was substantially reduced in cells incubated with palmitate at a concentration as low as 75 µM. This effect was not accompanied by excessive reactive oxygen species (ROS) generation or increased Jun N-terminal kinase (JNK) phosphorylation. Moreover, preincubation of AS-30D cells with rosiglitazone, an antidiabetic agonist of peroxisome proliferator-activated receptor gamma (PPARγ), efficiently prevented the palmitate-induced insulin resistance. We conclude that AS-30D hepatoma cells may be used as a model sensitive to insulin and vulnerable to palmitate-induced insulin resistance.

scholarly journals The Pal3 Promoter Sequence Is Critical for the Regulation of Human Renin Gene Transcription by Peroxisome Proliferator-Activated Receptor-γ

Endocrinology ◽  
2008 ◽  
Vol 149 (9) ◽  
pp. 4647-4657 ◽  
Author(s):  
Vladimir T. Todorov ◽  
Michael Desch ◽  
Thomas Schubert ◽  
Armin Kurtz
Keyword(s):  
Gene Expression ◽  
Gene Transcription ◽  
Promoter Activity ◽  
Peroxisome Proliferator ◽  
Response Element ◽  
Peroxisome Proliferator Activated Receptor ◽  
Human Renin ◽  
Pparγ Agonist ◽  
Renin Gene ◽  
Stimulation Of

We recently reported that human renin gene transcription is stimulated by the nuclear receptor peroxisome proliferator-activated receptor (PPAR)-γ in the renin-producing cell line Calu-6. The effect of PPARγ was mapped to two sequences in the renin promoter: a direct repeat hormone response element (HRE), which is related to the classical PPAR response element (PPRE) and a nonconsensus palindromic element with a 3-bp spacer (Pal3). We now find that PPARγ binds to the renin HRE. Neither the human renin HRE nor the consensus PPRE was sufficient to attain the maximal stimulation of renin promoter activity by the PPARγ agonist rosiglitazone. In contrast, the human renin Pal3 element mediates both the full PPARγ-dependent activation of transcription and the PPARγ-driven basal renin gene transcription. The human renin Pal3 sequence was found to selectively bind PPARγ and the retinoid X receptor-α from Calu-6 nuclear extracts. This is in contrast to the consensus PPRE, which can bind other nuclear proteins. PPARγ knockdown paradoxically did not attenuate the stimulation of the endogenous renin gene expression by rosiglitazone. Similarly, a deficiency of PPARγ did not attenuate the activation of the minimal human renin promoter, which contains the endogenous Pal3 motif. However, when the human renin Pal3 site was replaced by the consensus PPRE sequence, PPARγ knockdown abrogated the effect of rosiglitazone on renin promoter activity. Thus, the human renin Pal3 site appears to be critical for the PPARγ-dependent regulation of gene expression by mediating maximal transcription activation, particularly at the low cellular level of PPARγ.

Albumin and α-fetoprotein gene expression and DNA methylation in rat hepatoma cell lines

1988 ◽  
Vol 174 (2) ◽  
pp. 433-447 ◽  
Author(s):  
Wolfgang A. Schulz ◽  
Nancy Crawford ◽  
Joseph Locker
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Cell Lines ◽  
Hepatoma Cell ◽  
Hepatoma Cell Lines ◽  
Rat Hepatoma

scholarly journals Troglitazone Effects on Gene Expression in Human Skeletal Muscle of Type II Diabetes Involve Up-Regulation of Peroxisome Proliferator-Activated Receptor-γ1

1998 ◽  
Vol 83 (8) ◽  
pp. 2830-2835 ◽  
Author(s):  
Kyong Soo Park ◽  
Theodore P. Ciaraldi ◽  
Kristin Lindgren ◽  
Leslie Abrams-Carter ◽  
Sunder Mudaliar ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Type Ii Diabetes ◽  
Insulin Action ◽  
Peroxisome Proliferator ◽  
Type Ii ◽  
Peroxisome Proliferator Activated Receptor ◽  
Nondiabetic Control ◽  
Muscle Cultures ◽  
Stimulation Of

abstract Troglitazone, besides improving insulin action in insulin-resistant subjects, is also a specific ligand for the nuclear receptor peroxisome proliferator-activated receptor-γ (PPARγ). To determine whether troglitazone might enhance insulin action by stimulation of PPARγ gene expression in muscle, total PPARγ messenger RNA (mRNA), and protein were determined in skeletal muscle cultures from nondiabetic control and type II diabetic subjects before and after treatment of cultures with troglitazone (4 days ± troglitazone, 11.5μ m). Troglitazone treatment increased PPARγ mRNA levels up to 3-fold in muscle cultures from type II diabetics (277 ± 63 to 630 ± 100 × 103 copies/μg total RNA, P = 0.003) and in nondiabetic control subjects (200 ± 42 to 490 ± 81, P = 0.003). PPARγ protein levels in both diabetic (4.7 ± 1.6 to 13.6± 3.0 AU/10 μg protein, P < 0.02) and nondiabetic cells (7.4 ± 1.0 to 12.7 ± 1.8, P < 0.05) were also up-regulated by troglitazone treatment. Increased PPARγ was associated with stimulation of human adipocyte lipid binding protein (ALBP) and muscle fatty acid binding protein (mFABP) mRNA, without change in the mRNA for glycerol-3-phosphate dehydrogenase, PPARδ, myogenin, uncoupling protein-2, or sarcomeric α-actin protein. In summary, we showed that troglitazone markedly induces PPARγ, ALBP, and mFABP mRNA abundance in muscle cultures from both nondiabetic and type II diabetic subjects. Increased expression of PPARγ protein and other genes involved in glucose and lipid metabolism in skeletal muscle may account, in part, for the insulin sensitizing effects of troglitazone in type II diabetes.

scholarly journals The Human Na+-Taurocholate Cotransporting Polypeptide Gene Is Activated by Glucocorticoid Receptor and Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α, and Suppressed by Bile Acids via a Small Heterodimer Partner-Dependent Mechanism

2006 ◽  
Vol 20 (1) ◽  
pp. 65-79 ◽  
Author(s):  
Jyrki J. Eloranta ◽  
Diana Jung ◽  
Gerd A. Kullak-Ublick
Keyword(s):  
Bile Acid ◽  
Bile Acids ◽  
Human Hepatocytes ◽  
Farnesoid X Receptor ◽  
Peroxisome Proliferator ◽  
Acid Uptake ◽  
Peroxisome Proliferator Activated Receptor ◽  
Small Heterodimer Partner ◽  
Bile Acid Uptake ◽  
Sodium Dependent

Abstract Na+-taurocholate cotransporting polypeptide (NTCP) is the major bile acid uptake system in human hepatocytes. NTCP and the ileal transporter ASBT (apical sodium-dependent bile acid transporter) are two sodium-dependent transporters critical for the enterohepatic circulation of bile acids. The hASBT gene is known to be activated by the glucocorticoid receptor (GR). Here we show that GR also induces the endogenous hNTCP gene and transactivates the reporter-linked hNTCP promoter, in the presence of its ligand dexamethasone. Mutational analysis of the hNTCP promoter identified a functional GR response element, with which GR directly interacts within living cells. The GR/dexamethasone activation of endogenous hNTCP expression was suppressed by bile acids, in a manner dependent on the bile acid receptor farnesoid X receptor. Overexpression of the farnesoid X receptor-inducible transcriptional repressor small heterodimer partner also suppressed the GR/dexamethasone-activation of the hNTCP promoter. The peroxisome proliferator-activated receptor-γ coactivator-1α enhanced the GR/dexamethasone activation of the hNTCP promoter. In conclusion, the hNTCP promoter is activated by GR in a ligand-dependent manner, similarly to the hASBT promoter. Thus, glucocorticoids may coordinately regulate the major bile acid uptake systems in human liver and intestine. The GR/dexamethasone activation of the hNTCP promoter is counteracted by bile acids and small heterodimer partner, providing a negative feedback mechanism for bile acid uptake in human hepatocytes.

scholarly journals Distinct Regulation of Hepatitis B Virus Biosynthesis by Peroxisome Proliferator-Activated Receptor γ Coactivator 1α and Small Heterodimer Partner in Human Hepatoma Cell Lines

2009 ◽  
Vol 83 (23) ◽  
pp. 12545-12551 ◽  
Author(s):  
Caitlin R. Ondracek ◽  
Vanessa C. Reese ◽  
Christel N. Rushing ◽  
Claudia E. Oropeza ◽  
Alan McLachlan
Keyword(s):  
Cell Lines ◽  
Nuclear Receptors ◽  
Hepatoma Cell ◽  
Peroxisome Proliferator ◽  
Human Hepatoma ◽  
Human Hepatoma Cell ◽  
Peroxisome Proliferator Activated Receptor ◽  
Hepatoma Cell Lines ◽  
Huh7 Cells ◽  
B Virus

ABSTRACT The human hepatoma cell lines HepG2 and Huh7 have been used extensively to study hepatitis B virus (HBV) transcription and replication. Both cell lines support transcription of the 3.5-kb viral pregenomic RNA and subsequent viral DNA synthesis by reverse transcription. The effects of the coactivator peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α) and corepressor small heterodimer partner (SHP) on HBV transcription and replication mediated by nuclear receptors were examined in the context of individual nuclear receptors in nonhepatoma cells and in hepatoma cells in an attempt to determine the relative contribution of the various nuclear receptors to viral biosynthesis in the hepatoma cells. PGC1α and SHP modulated viral biosynthesis differently in the human hepatoma cell lines HepG2 and Huh7, indicating distinct modes of transcriptional regulation. Consistent with this suggestion, it appears that retinoid X receptor α/farnesoid X receptor α and liver receptor homolog 1 or estrogen-related receptor β (ERRβ) may contribute to the majority of the viral replication observed in HepG2 cells, whereas ERRα and ERRγ are probably responsible for the majority of viral biosynthesis in Huh7 cells. Therefore, this approach indicates that the transcriptional regulation of HBV biosynthesis in HepG2 and Huh7 cells is primarily controlled by different transcription factors.

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