Troglitazone and pioglitazone interactions via PPAR-γ-independent and -dependent pathways in regulating physiological responses in renal tubule-derived cell lines

2007 ◽  
Vol 292 (3) ◽  
pp. C1137-C1146 ◽  
Author(s):  
Francesco Turturro ◽  
Robert Oliver ◽  
Ellen Friday ◽  
Itzhak Nissim ◽  
Tomas Welbourne
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Biological Effects ◽  
Cellular Growth ◽  
Glutamine Metabolism ◽  
Peroxisome Proliferator ◽  
Renal Tubules ◽  
Erk Activation ◽  
Ppar Γ

Troglitazone (Tro) and pioglitazone (Pio) activation of peroxisome proliferator-activated receptor (PPAR)-γ and PPAR-γ-independent pathways was studied in cell lines derived from porcine renal tubules. PPAR-γ-dependent activation of PPAR response element-driven luciferase gene expression was observed with Pio at 1 μM but not Tro at 1 μM. On the other hand, PPAR-γ-independent P-ERK activation was observed with 5 μM Tro but not with Pio (5–20 μM). In addition, Pio (1–10 μM) increased metabolic acid production and activated AMP-activated protein kinase (AMPK) associated with decreased mitochondrial membrane potential, whereas Tro (1–20 μM) did not. These results are consistent with three pathways through which glitazones may act in effecting metabolic processes (ammoniagenesis and gluconeogenesis) as well as cellular growth: 1) PPAR-γ-dependent and PPAR-γ-independent pathways, 2) P-ERK activation, and 3) mitochondrial AMPK activation. The pathways influence cellular acidosis and glucose and glutamine metabolism in a manner favoring reduced plasma glucose in vivo. In addition, significant interactions can be demonstrated that enhance some physiological processes (ammoniagenesis) and suppress others (ligand-mediated PPAR-γ gene expression). Our findings provide a model both for understanding seemingly opposite biological effects and for enhancing therapeutic potency of these agents.

scholarly journals The Peroxisome Proliferator-Activated Receptor N-Terminal Domain Controls Isotype-Selective Gene Expression and Adipogenesis

2006 ◽  
Vol 20 (6) ◽  
pp. 1261-1275 ◽  
Author(s):  
Sarah Hummasti ◽  
Peter Tontonoz
Keyword(s):  
Gene Expression ◽  
Fatty Acid ◽  
Target Genes ◽  
Biological Effects ◽  
Binding Domain ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
N Terminus

Abstract Peroxisome proliferator-activated receptors (PPARγ, PPARα, and PPARδ) are important regulators of lipid metabolism. Although they share significant structural similarity, the biological effects associated with each PPAR isotype are distinct. For example, PPARα and PPARδ regulate fatty acid catabolism, whereas PPARγ controls lipid storage and adipogenesis. The different functions of PPARs in vivo can be explained at least in part by the different tissue distributions of the three receptors. The question of whether the receptors have different intrinsic activities and regulate distinct target genes, however, has not been adequately explored. We have engineered cell lines that express comparable amounts of each receptor. Transcriptional profiling of these cells in the presence of selective agonists reveals partially overlapping but distinct patterns of gene regulation by the three PPARs. Moreover, analysis of chimeric receptors points to the N terminus of each receptor as the key determinant of isotype-selective gene expression. For example, the N terminus of PPARγ confers the ability to promote adipocyte differentiation when fused to the PPARδ DNA binding domain and ligand binding domain, whereas the N terminus of PPARδ leads to the inappropriate expression of fatty acid oxidation genes in differentiated adipocytes when fused to PPARγ. Finally, we demonstrate that the N terminus of each receptor functions in part to limit receptor activity because deletion of the N terminus leads to nonselective activation of target genes. A more detailed understanding of the mechanisms by which the individual PPARs differentially regulate gene expression should aid in the design of more effective drugs, including tissue- and target gene-selective PPAR modulators.

Studies of Metabolism Mediated Mutagenicity In Vitro

1990 ◽  
Vol 18 (1_part_1) ◽  
pp. 243-250
Author(s):  
Dag Jenssen ◽  
Lennart Romert
Keyword(s):  
Cell Lines ◽  
Biological Effects ◽  
Animal Experiments ◽  
Culture Technique ◽  
Organ Perfusion ◽  
Isolated Cells ◽  
Toxicological Effect ◽  
In Vitro Methods

To understand the cause of the biological effects of xenobiotic metabolism in mammals, investigators have traditionally performed animal experiments by comparing the results of biochemical methods, such as measurement of enzyme activity analysis of the metabolites produced, with the observed toxicological effect. This article deals with in vitro methods for genotoxicity combined with drug metabolising preparations at the organelle, cell or organ levels, as exemplified by microsome preparations, isolated cells/cell lines and organ perfusion systems, respectively. The advantage of some of these methods for studying metabolism-mediated mutagenicity is that the measured endpoint reflects not only the bioactivating phase I reactions, but also the detoxifying phase II reactions, and the transfer of the non-conjugated reactive metabolites to other cells and their ability to cause mutations in these cells. In vivo, all these events are important factors in the initiation of cancer. A mechanistic advantage of the methods for metabolism-mediated mutagenicity in vitro is that the relevance of the different steps in metabolism for the mutational events can seldom be investigated in an in vivo assay. Furthermore, human studies can easily be performed using the co-culture technique with isolated human cells or cell lines.

scholarly journals Opposing Roles of Peroxisome Proliferator-activated Receptor α and Growth Hormone in the Regulation of CYP4A11 Expression in a Transgenic Mouse Model

2009 ◽  
Vol 284 (24) ◽  
pp. 16541-16552 ◽  
Author(s):  
Üzen Savas ◽  
Daniel E. W. Machemer ◽  
Mei-Hui Hsu ◽  
Pryce Gaynor ◽  
Jerome M. Lasker ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Hormone ◽  
Transgenic Mice ◽  
Hormone Secretion ◽  
Growth Hormone Secretion ◽  
Peroxisome Proliferator ◽  
Sexually Dimorphic ◽  
Peroxisome Proliferator Activated Receptor ◽  
Liver And Kidney

CYP4A11 transgenic mice (CYP4A11 Tg) were generated to examine in vivo regulation of the human CYP4A11 gene. Expression of CYP4A11 in mice yields liver and kidney P450 4A11 levels similar to those found in the corresponding human tissues and leads to an increased microsomal capacity for ω-hydroxylation of lauric acid. Fasted CYP4A11 Tg mice exhibit 2–3-fold increases in hepatic CYP4A11 mRNA and protein, and this response is absent in peroxisome proliferator-activated receptor α (PPARα) null mice. Dietary administration of either of the PPARα agonists, fenofibrate or clofibric acid, increases hepatic and renal CYP4A11 levels by 2–3-fold, and these responses were also abrogated in PPARα null mice. Basal liver CYP4A11 levels are reduced differentially in PPARα−/− females (>95%) and males (<50%) compared with PPARα−/+ mice. Quantitative and temporal differences in growth hormone secretion are known to alter hepatic lipid metabolism and to underlie sexually dimorphic gene expression, respectively. Continuous infusion of low levels of growth hormone reduced CYP4A11 expression by 50% in PPARα-proficient male and female transgenic mice. A larger decrease was observed for the expression of CYP4A11 in PPARα−/− CYP4A11 Tg male mice to levels similar to that of female PPARα-deficient mice. These results suggest that PPARα contributes to the maintenance of basal CYP4A11 expression and mediates CYP4A11 induction in response to fibrates or fasting. In contrast, increased exposure to growth hormone down-regulates CYP4A11 expression in liver.

Bcl-2 protein localizes to the chromosomes of mitotic nuclei and is correlated with the cell cycle in cultured epithelial cell lines

1994 ◽  
Vol 107 (2) ◽  
pp. 363-371
Author(s):  
Q.L. Lu ◽  
A.M. Hanby ◽  
M.A. Nasser Hajibagheri ◽  
S.E. Gschmeissner ◽  
P.J. Lu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Epithelial Cell ◽  
Cell Lines ◽  
Cytoplasmic Localization ◽  
Human Epithelial Cell ◽  
Daughter Cells ◽  
Epithelial Cell Lines ◽  
Cell Immortalization

bcl-2 gene expression confers a survival advantage by preventing cells from entering apoptosis. In contrast to the previously described cytoplasmic localization of Bcl-2 in epithelial cells in vivo, in this study we have demonstrated, in a series of human epithelial cell lines, that Bcl-2 also localizes to mitotic nuclei. Both immunocytochemical and immunoelectron microscopical examinations localize this protein to nuclei and in particular to chromosomes. Nuclear Bcl-2 expression in these cell lines is correlated with the cell cycle. There is relatively strong expression during mitosis, most intense during prophase and metaphase, declining in telophase and then the protein becomes undetectable soon after separation of the two daughter cells. The expression and distribution of Bcl-2 is influenced by treatment with excessive thymidine. These results indicate that Bcl-2 may protect the cells from apoptosis occurring during mitosis and suggest a possible role for the protein in cell immortalization.

scholarly journals Peroxisome Proliferator-Activated Receptor-α Control of Lipid and Glucose Metabolism in Human White Adipocytes

Endocrinology ◽  
2010 ◽  
Vol 151 (1) ◽  
pp. 123-133 ◽  
Author(s):  
Carole Ribet ◽  
Emilie Montastier ◽  
Carine Valle ◽  
Véronic Bezaire ◽  
Anne Mazzucotelli ◽  
...  
Keyword(s):  
Gene Expression ◽  
Biological Effects ◽  
Primary Cultures ◽  
Lactate Production ◽  
De Novo Lipogenesis ◽  
Peroxisome Proliferator ◽  
Palmitate Oxidation ◽  
White Adipocytes ◽  
Pparγ Agonist ◽  
Pparα Agonist

Abstract This work aimed at characterizing the role of peroxisome proliferator-activated receptors (PPAR)α in human white adipocyte metabolism and at comparing PPARα and PPARγ actions in these cells. Primary cultures of human fat cells were treated with the PPARα agonist GW7647 or the PPARγ agonist rosiglitazone. Changes in gene expression were determined using DNA microrrays and quantitative RT-PCR. Western blot and metabolic studies were performed to identify the biological effects elicited by PPAR agonist treatments. GW7647 induced an up-regulation of β-oxidation gene expression and increased palmitate oxidation. Unexpectedly, glycolysis was strongly reduced at transcriptional and functional levels by GW7647 leading to a decrease in pyruvate and lactate production. Glucose oxidation was decreased. Triglyceride esterification and de novo lipogenesis were inhibited by the PPARα agonist. GW7647-induced alterations were abolished by a treatment with a PPARα antagonist. Small interfering RNA-mediated extinction of PPARα gene expression in hMADS adipocytes attenuated GW7647 induction of palmitate oxidation. Rosiglitazone had no major impact on glycolysis and β-oxidation. Altogether these results show that PPARα can selectively up-regulate β-oxidation and decrease glucose utilization in human white adipocytes.

scholarly journals Gene Transfer into the Lung by Nanoparticle Dextran-Spermine/Plasmid DNA Complexes

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Syahril Abdullah ◽  
Wai Yeng Wendy-Yeo ◽  
Hossein Hosseinkhani ◽  
Mohsen Hosseinkhani ◽  
Ehab Masrawa ◽  
...  
Keyword(s):  
Gene Expression ◽  
Gene Transfer ◽  
Cell Lines ◽  
Plasmid Dna ◽  
Mixing Ratio ◽  
Systemic Delivery ◽  
Clear Trend ◽  
Assay Time

A novel cationic polymer, dextran-spermine (D-SPM), has been found to mediate gene expression in a wide variety of cell lines andin vivothrough systemic delivery. Here, we extended the observations by determining the optimal conditions for gene expression of D-SPM/plasmid DNA (D-SPM/pDNA) in cell lines and in the lungs of BALB/c mice via instillation delivery.In vitrostudies showed that D-SPM could partially protect pDNA from degradation by nuclease and exhibited optimal gene transfer efficiency at D-SPM to pDNA weight-mixing ratio of 12. In the lungs of mice, the levels of gene expression generated by D-SPM/pDNA are highly dependent on the weight-mixing ratio of D-SPM to pDNA, amount of pDNA in the complex, and the assay time postdelivery. Readministration of the complex at day 1 following the first dosing showed no significant effect on the retention and duration of gene expression. The study also showed that there was a clear trend of increasing size of the complexes as the amount of pDNA was increased, where the sizes of the D-SPM/pDNA complexes were within the nanometer range.

scholarly journals PPAR, PTEN, and the Fight against Cancer

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Rosemary E. Teresi ◽  
Kristin A. Waite
Keyword(s):  
Tumor Suppressor ◽  
Hormone Receptors ◽  
Susceptibility Gene ◽  
Genetic Alterations ◽  
Cellular Growth ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

Peroxisome proliferator-activated receptor gamma (PPAR) is a ligand-activated transcription factor, which belongs to the family of nuclear hormone receptors. Recent in vitro studies have shown that PPAR can regulate the transcription ofphosphatase and tensin homolog on chromosometen(PTEN), a known tumor suppressor.PTENis a susceptibility gene for a number of disorders, including breast and thyroid cancer. Activation of PPAR through agonists increases functional PTEN protein levels that subsequently induces apoptosis and inhibits cellular growth, which suggests that PPAR may be a tumor suppressor. Indeed, several in vivo studies have demonstrated that genetic alterations of PPAR can promote tumor progression. These results are supported by observations of the beneficial effects of PPAR agonists in the in vivo cancer setting. These studies signify the importance of PPAR andPTEN's interaction in cancer prevention.

scholarly journals Piperine Alleviates Doxorubicin-Induced Cardiotoxicity via Activating PPAR-γ in Mice

PPAR Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Yan ◽  
Si-Chi Xu ◽  
Chun-Yan Kong ◽  
Xiao-Yang Zhou ◽  
Zhou-Yan Bian ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiac Injury ◽  
Inflammatory Factors ◽  
Peroxisome Proliferator ◽  
Protective Effects ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Myocardial Oxidative Stress

Background. Oxidative stress, inflammation and cardiac apoptosis were closely involved in doxorubicin (DOX)-induced cardiac injury. Piperine has been reported to suppress inflammatory response and pyroptosis in macrophages. However, whether piperine could protect the mice against DOX-related cardiac injury remain unclear. This study aimed to investigate whether piperine inhibited DOX-related cardiac injury in mice. Methods. To induce DOX-related acute cardiac injury, mice in DOX group were intraperitoneally injected with a single dose of DOX (15 mg/kg). To investigate the protective effects of piperine, mice were orally treated for 3 weeks with piperine (50 mg/kg, 18:00 every day) beginning two weeks before DOX injection. Results. Piperine treatment significantly alleviated DOX-induced cardiac injury, and improved cardiac function. Piperine also reduced myocardial oxidative stress, inflammation and apoptosis in mice with DOX injection. Piperine also improved cell viability, and reduced oxidative damage and inflammatory factors in cardiomyocytes. We also found that piperine activated peroxisome proliferator-activated receptor-γ (PPAR-γ), and the protective effects of piperine were abolished by the treatment of the PPAR-γ antagonist in vivo and in vitro. Conclusions. Piperine could suppress DOX-related cardiac injury via activation of PPAR-γ in mice.

scholarly journals Foxa3 (HNF-3γ) binds to and activates the rat proglucagon gene promoter but is not essential for proglucagon gene expression

2002 ◽  
Vol 366 (2) ◽  
pp. 633-641 ◽  
Author(s):  
Yuanfang LIU ◽  
Wei SHEN ◽  
Patricia L. BRUBAKER ◽  
Klaus H. KAESTNER ◽  
Daniel J. DRUCKER
Keyword(s):  
Gene Expression ◽  
Cell Lines ◽  
Promoter Activity ◽  
Gene Promoter ◽  
Forkhead Box ◽  
Mild Hypoglycaemia ◽  
Element Binding Protein ◽  
Prolonged Fast

Members of the Forkhead box a (Foxa) transcription factor family are expressed in the liver, pancreatic islets and intestine and both Foxa1 and Foxa2 regulate proglucagon gene transcription. As Foxa proteins exhibit overlapping DNA-binding specificities, we examined the role of Foxa3 [hepatocyte nuclear factor (HNF)-3γ] in control of proglucagon gene expression. Foxa3 was detected by reverse transcriptase PCR in glucagon-producing cell lines and binds to the rat proglucagon gene G2 promoter element in GLUTag enteroendocrine cells. Although Foxa3 increased rat proglucagon promoter activity in BHK fibroblasts, augmentation of Foxa3 expression did not increase proglucagon promoter activity in GLUTag cells. Furthermore, adenoviral Foxa3 expression did not affect endogenous proglucagon gene expression in islet or intestinal endocrine cell lines. Although Foxa3-/- mice exhibit mild hypoglycaemia during a prolonged fast, the levels of proglucagon-derived peptides and proglucagon mRNA transcripts were comparable in tissues from wild-type and Foxa3-/- mice. These findings identify Foxa3 as a member of the proglucagon gene G2 element binding-protein family that, unlike Foxa1, is not essential for control of islet or intestinal proglucagon gene expression in vivo.

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