Abstract 301: Initial Increase of Klf5 and Ppara Expression After Myocardial Ischemia/Reperfusion in Mice Appears to be Critical for Survival

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Christine J Pol ◽  
Mesele-Christina Valenti ◽  
Sarah M Schumacher ◽  
Ancai Yuan ◽  
Erhe Gao ◽  
...  
Keyword(s):  
Mrna Expression ◽  
Ischemia Reperfusion ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Oxidation ◽  
Initial Increase ◽  
Peroxisome Proliferator ◽  
Wild Type ◽  
Peroxisome Proliferator Activated Receptor ◽  
Myocardial Ischemia Reperfusion

Krüppel-like factors (KLF) have important roles in metabolism. We previously found that KLF5 is a positive transcriptional regulator of peroxisome proliferator-activated receptor α ( Ppara) , a central regulator of cardiac fatty acid oxidation (FAO). Mice with cardiomyocyte-specific Klf5 ablation ( α MHC-Klf5 -/- ) had reduced cardiac Ppara expression and FAO. At age 6-12 months these mice develop distinct cardiac dysfunction. The role of PPARα activation in I/R injury is unclear as both beneficial and detrimental effects have been reported. We aimed to study if Ppara expression changes during I/R are driven by KLF5 and explore its protective or detrimental role. Wild type mice were subjected to in vivo I/R or sham surgery. I/R resulted in an initial increase in Ppara , and its target gene pyruvate dehydrogenase kinase 4 ( Pdk4) mRNA after 2h reperfusion, followed by decreased expression after 24h reperfusion. The Ppara expression is associated with parallel changes in cardiac Klf5 mRNA expression. Concurrent, there was a decrease of cardiac FAO-related genes carnitine palmitoyl-transferase 1β ( Cpt1b), very long chain acyl-CoA dehydrogenase (Vlcad), and acyl-CoA oxidase ( Aox) in mice with I/R. To define the cell type causing the temporal changes in Klf5 and Ppara after I/R we isolated primary cardiomyocytes and fibroblasts. Our data suggest a similar effect in primary isolated cardiomyocytes only. Klf5 mRNA expression is increased after 2 hour hypoxia and normalized after 4 hour re-oxygenation in cardiomyocytes, whereas there are no changes after hypoxia/normoxia in fibroblasts. To assess the importance of cardiomyocyte KLF5 in I/R we used α MHC-Klf5 -/- mice. Interestingly, despite reduced FAO, 7 month old αMHC-Klf5 -/- mice subjected to I/R had a marked increase in mortality; 4 of 7 αMHC-Klf5 -/- mice died within the first 24h of reperfusion while no mortality was observed in age-matched wild type mice that underwent I/R. In conclusion, I/R is associated with an increase in Klf5 and Ppara in the first hours of reperfusion followed by a decrease in Klf5 and Ppara , likely accounted for by cardiomyocytes. Increased mortality for α MHC-Klf5 -/- mice with I/R injury suggests that the initial increase may be an adaptive response that is critical for survival.

scholarly journals Evaluation of the role of peroxisome-proliferator-activated receptor α in the regulation of cardiac pyruvate dehydrogenase kinase 4 protein expression in response to starvation, high-fat feeding and hyperthyroidism

2002 ◽  
Vol 364 (3) ◽  
pp. 687-694 ◽  
Author(s):  
Mark J. HOLNESS ◽  
Nicholas D. SMITH ◽  
Karen BULMER ◽  
Teresa HOPKINS ◽  
Geoffrey F. GIBBONS ◽  
...  
Keyword(s):  
Protein Expression ◽  
Pyruvate Dehydrogenase ◽  
Fold Increase ◽  
Pyruvate Dehydrogenase Kinase ◽  
Peroxisome Proliferator ◽  
Wild Type ◽  
High Fat ◽  
Peroxisome Proliferator Activated Receptor

Inactivation of cardiac pyruvate dehydrogenase complex (PDC) after prolonged starvation and in response to hyperthyroidism is associated with enhanced protein expression of pyruvate dehydrogenase kinase (PDK) isoform 4. The present study examined the potential role of peroxisome-proliferator-activated receptor α (PPARα) in adaptive modification of cardiac PDK4 protein expression after starvation and in hyperthyroidism. PDK4 protein expression was analysed by immunoblotting in homogenates of hearts from fed or 48h-starved rats, rats rendered hyperthyroid by subcutaneous injection of tri-iodothyronine and a subgroup of euthyroid rats maintained on a high-fat/low-carbohydrate diet, with or without treatment with the PPARα agonist WY14,643. In addition, PDK4 protein expression was analysed in hearts from fed, 24h-starved or 6h-refed wild-type or PPARα-null mice. PPARα activation by WY14,643 in vivo over the timescale of the response to starvation failed to up-regulate cardiac PDK4 protein expression in rats maintained on standard diet (WY14,643, 1.1-fold increase; starvation, 1.8-fold increase) or influence the cardiac PDK4 response to starvation. By contrast, PPARα activation by WY14,643 in vivo significantly enhanced cardiac PDK4 protein expression in rats maintained on a high-fat diet, which itself increased cardiac PDK4 protein expression. PPARα deficiency did not abolish up-regulation of cardiac PDK4 protein expression in response to starvation (2.9-fold increases in both wild-type and PPARα-null mice). Starvation and hyperthyroidism exerted additive effects on cardiac PDK4 protein expression, but PPARα activation by WY14,643 did not influence the response of cardiac PDK4 protein expression to hyperthyroidism in either the fed or starved state. Our data support the hypothesis that cardiac PDK4 protein expression is regulated, at least in part, by a fatty acid-dependent, PPARα-independent mechanism and strongly implicate a fall in insulin in either initiating or facilitating the response of cardiac PDK4 protein expression to starvation.

Control of cardiac pyruvate dehydrogenase activity in peroxisome proliferator-activated receptor-α transgenic mice

2003 ◽  
Vol 285 (1) ◽  
pp. H270-H276 ◽  
Author(s):  
Teresa A. Hopkins ◽  
Mary C. Sugden ◽  
Mark J. Holness ◽  
Ray Kozak ◽  
Jason R. B. Dyck ◽  
...  
Keyword(s):  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Pyruvate Dehydrogenase ◽  
Glucose Oxidation ◽  
Pyruvate Dehydrogenase Kinase ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Wild Type ◽  
Peroxisome Proliferator Activated Receptor ◽  
Oxidation Rates

The pyruvate dehydrogenase enzyme complex (PDC) is rate limiting for glucose oxidation in the heart. Inhibition of PDC by end-product feedback and phosphorylation by pyruvate dehydrogenase kinase (PDK) operate in concert to inhibit PDC activity. Because the transcriptional regulator peroxisome proliferator-activated receptor (PPAR)-α increases PDK expression in some tissues, we examined what role PPAR-α has in regulating glucose oxidation in hearts from mice overexpressing PPAR-α (MHC-PPAR-α mice). Glucose oxidation rates were decreased in isolated working hearts from MHC-PPAR-α mice compared with wild-type littermates (428 ± 113 vs. 771 ± 63 nmol · g dry weight-1 · min-1, respectively), which was accompanied by a parallel increase in fatty acid oxidation. However, there was no difference in PDC activity between MHC-PPAR-α and wild-type animals, even though the expression of the PDK isoform PDK1 was increased in MHC-PPAR-α mice. Glucose oxidation rates in both MHC-PPAR-α and wild-type mouse hearts were decreased after 48-h fasting (which increases PPAR-α expression) or by treatment of mice with the PPAR-α agonist WY-14,643 for 1 wk. Despite this, PDC activity in both animal groups was not altered. Taken together, these data suggest that glucose oxidation rates in the heart can be dramatically altered independent of PDK phosphorylation and inhibition of PDC by PDK. It also suggests that PPAR-α activation decreases glucose oxidation in hearts mainly by decreasing the flux of pyruvate through PDC due to negative feedback of PDC by fatty acid oxidation reaction products rather than by the phosphorylated state of the PDC complex.

scholarly journals Adipocyte PHLPP2 inhibition prevents obesity-induced fatty liver

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
KyeongJin Kim ◽  
Jin Ku Kang ◽  
Young Hoon Jung ◽  
Sang Bae Lee ◽  
Raffaela Rametta ◽  
...  
Keyword(s):  
Fatty Liver ◽  
Whole Body ◽  
Acid Oxidation ◽  
Chow Diet ◽  
Peroxisome Proliferator ◽  
Obese Mice ◽  
Ph Domain ◽  
Peroxisome Proliferator Activated Receptor

AbstractIncreased adiposity confers risk for systemic insulin resistance and type 2 diabetes (T2D), but mechanisms underlying this pathogenic inter-organ crosstalk are incompletely understood. We find PHLPP2 (PH domain and leucine rich repeat protein phosphatase 2), recently identified as the Akt Ser473 phosphatase, to be increased in adipocytes from obese mice. To identify the functional consequence of increased adipocyte PHLPP2 in obese mice, we generated adipocyte-specific PHLPP2 knockout (A-PHLPP2) mice. A-PHLPP2 mice show normal adiposity and glucose metabolism when fed a normal chow diet, but reduced adiposity and improved whole-body glucose tolerance as compared to Cre- controls with high-fat diet (HFD) feeding. Notably, HFD-fed A-PHLPP2 mice show increased HSL phosphorylation, leading to increased lipolysis in vitro and in vivo. Mobilized adipocyte fatty acids are oxidized, leading to increased peroxisome proliferator-activated receptor alpha (PPARα)-dependent adiponectin secretion, which in turn increases hepatic fatty acid oxidation to ameliorate obesity-induced fatty liver. Consistently, adipose PHLPP2 expression is negatively correlated with serum adiponectin levels in obese humans. Overall, these data implicate an adipocyte PHLPP2-HSL-PPARα signaling axis to regulate systemic glucose and lipid homeostasis, and suggest that excess adipocyte PHLPP2 explains decreased adiponectin secretion and downstream metabolic consequence in obesity.

Abstract 331: Recovery of Mitochondrial Bioenergetics after Hypoxia via Regulating Pyruvate Dehydrogenase Kinase and Adenosine Monophosphate-activated Kinase

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Jessica M Toli ◽  
Minzhen He ◽  
Carolyn Suzuki ◽  
Maha Abdellatif
Keyword(s):  
Fatty Acid ◽  
Oxidative Phosphorylation ◽  
Cardiac Myocytes ◽  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Kinase ◽  
Neonatal Rat ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Mitochondrial Bioenergetics ◽  
Peroxisome Proliferator Activated Receptor

Mitochondrial quality control is critical for the survival of cardiac myocytes during stress. The purpose of this study was to examine the effect of metabolic substrates and regulators of metabolism on mitochondrial bioenergetics, as an indicator of mitochondrial quality, and how these factors might influence the recovery of the cell’s bioenergetics after hypoxia/ischemia. By monitoring oxygen consumption rates (OCR), in real-time, in live neonatal rat myocytes and human cardiac myocyte-differentiated induced pluripotent stem cells, we found that both cell types can maintain basal OCR efficiently with any metabolic substrate; however, the neonatal cells require both glucose and fatty acid, while the human adult cells require fatty acid only, for mounting maximum reserve respiratory capacity (RRC). Our data also show that subjecting cardiac myocytes to hypoxia results in a reduction of the cells’ basal OCR and oxidative phosphorylation, and exhausts the RRC, which is accompanied by an increase in pyruvate dehydrogenase kinase (Pdk) 1 and 4. Except for normalization of Pdk1 levels, there was little or no recovery of these parameters after reoxygenation. We, thus, hypothesized, that inhibition of Pdks may help recovery of the cell’s bioenergetics. Indeed, our results show that by inhibiting Pdks with dichloroacetate (DCA) before or after hypoxia, the cells’ bioenergetics, including OCR, oxidative phosphorylation, and RRC in neonatal myocytes, and RRC in the human myocytes fully recover within 24 h. On the other hand, activating AMP-activated kinase (AMPK) resulted in delayed (96 h) improvement of the cells’ RRC that was accompanied by an increase in peroxisome proliferator-activated receptor gamma, coactivator 1α (3.5x), peroxisome proliferator-activated receptor-α (2x), and mitochondrial number (2x). These results led us to conclude that compromised mitochondrial quality can be rescued through mechanisms that regulate glucose or fatty acid oxidation by either inhibiting Pdks or activating AMPK, respectively, in rodent and human myocytes.

scholarly journals Soluble epoxide hydrolase inhibition and gene deletion are protective against myocardial ischemia-reperfusion injury in vivo

2008 ◽  
Vol 295 (5) ◽  
pp. H2128-H2134 ◽  
Author(s):  
Atsuko Motoki ◽  
Matthias J. Merkel ◽  
William H. Packwood ◽  
Zhiping Cao ◽  
Lijuan Liu ◽  
...  
Keyword(s):  
Myocardial Ischemia ◽  
Reperfusion Injury ◽  
Epoxide Hydrolase ◽  
Gene Deletion ◽  
Ischemia Reperfusion Injury ◽  
Ischemia Reperfusion ◽  
Wild Type ◽  
Myocardial Ischemia Reperfusion Injury ◽  
Myocardial Ischemia Reperfusion

Soluble epoxide hydrolase (sEH) metabolizes epoxyeicosatrienoic acids (EETs) to dihydroxyeicosatrienoic acids. EETs are formed from arachidonic acid during myocardial ischemia and play a protective role against ischemic cell death. Deletion of sEH has been shown to be protective against myocardial ischemia in the isolated heart preparation. We tested the hypothesis that sEH inactivation by targeted gene deletion or pharmacological inhibition reduces infarct size (I) after regional myocardial ischemia-reperfusion injury in vivo. Male C57BL\6J wild-type or sEH knockout mice were subjected to 40 min of left coronary artery (LCA) occlusion and 2 h of reperfusion. Wild-type mice were injected intraperitoneally with 12-(3-adamantan-1-yl-ureido)-dodecanoic acid butyl ester (AUDA-BE), a sEH inhibitor, 30 min before LCA occlusion or during ischemia 10 min before reperfusion. 14,15-EET, the main substrate for sEH, was administered intravenously 15 min before LCA occlusion or during ischemia 5 min before reperfusion. The EET antagonist 14,15-epoxyeicosa-5(Z)-enoic acid (EEZE) was given intravenously 15 min before reperfusion. Area at risk (AAR) and I were assessed using fluorescent microspheres and triphenyltetrazolium chloride, and I was expressed as I/AAR. I was significantly reduced in animals treated with AUDA-BE or 14,15-EET, independent of the time of administration. The cardioprotective effect of AUDA-BE was abolished by the EET antagonist 14,15-EEZE. Immunohistochemistry revealed abundant sEH protein expression in left ventricular tissue. Strategies to increase 14,15-EET, including sEH inactivation, may represent a novel therapeutic approach for cardioprotection against myocardial ischemia-reperfusion injury.

Coronary endothelial P-selectin in pathogenesis of myocardial ischemia-reperfusion injury

1998 ◽  
Vol 275 (5) ◽  
pp. H1865-H1872 ◽  
Author(s):  
Anthony J. Palazzo ◽  
Steven P. Jones ◽  
Donald C. Anderson ◽  
D. Neil Granger ◽  
David J. Lefer
Keyword(s):  
Myocardial Ischemia ◽  
Infarct Size ◽  
Ischemia Reperfusion Injury ◽  
Myocardial Infarct ◽  
Ischemia Reperfusion ◽  
Myocardial Infarct Size ◽  
Wild Type ◽  
Area At Risk ◽  
Myocardial Ischemia Reperfusion

We investigated in vivo coronary P-selectin expression and its pathophysiological consequences in a murine model of myocardial ischemia-reperfusion (MI/R) using wild-type and P-selectin deficient (−/−) mice. Coronary P-selectin expression [μg monoclonal antibody (MAb)/g tissue] was measured using a radiolabeled MAb method after 30 min of myocardial ischemia and 20 min of reperfusion. P-selectin expression in wild-type mice was significantly ( P< 0.01) elevated in the ischemic zone (0.070 ± 0.010) compared with the nonischemic zone (0.037 ± 0.008). Myocardial P-selectin expression was nearly undetectable in P-selectin −/− mice after MI/R. Furthermore, myocardial infarct size (% of area at risk) after 30 min of myocardial ischemia and 120 min of reperfusion was 42.5 ± 4.4 in wild-type mice and 24.4 ± 4.0 in P-selectin −/− mice ( P < 0.05). In additional experiments of prolonged myocardial ischemia (60 min) and reperfusion (120 min), myocardial infarct size was similar in P-selectin −/− mice and wild-type mice. Our results clearly demonstrate the involvement of coronary P-selectin in the development of myocardial infarction after MI/R.

scholarly journals Therapeutic effect of dichloroacetate against atherosclerosis via hepatic FGF21 induction mediated by acute AMPK activation

2019 ◽  
Vol 51 (10) ◽  
pp. 1-12 ◽  
Author(s):  
Byong-Keol Min ◽  
Chang Joo Oh ◽  
Sungmi Park ◽  
Ji-Min Lee ◽  
Younghoon Go ◽  
...  
Keyword(s):  
Energy Expenditure ◽  
Mrna Expression ◽  
Metabolic Activation ◽  
Pyruvate Dehydrogenase Kinase ◽  
Fibroblast Growth Factor 21 ◽  
High Morbidity ◽  
Peroxisome Proliferator ◽  
Dependent Manner ◽  
Brown Adipose

Abstract Dyslipidemia-induced atherosclerosis, which has a risk of high morbidity and mortality, can be alleviated by metabolic activation associated with mitochondrial function. The effect of dichloroacetate (DCA), a general pyruvate dehydrogenase kinase (PDK) inhibitor, on in vivo energy expenditure in ApoE−/− mice fed a western diet (WD) has not yet been investigated. WD-fed ApoE−/− mice developed atherosclerotic plaques and hyperlipidemia along with obesity, which were significantly ameliorated by DCA administration. Increased oxygen consumption was associated with heat production in the DCA-treated group, with no change in food intake or physical activity compared with those of the control. These processes were correlated with the increased gene expression of Dio2 and Ucp-1, which represents brown adipose tissue (BAT) activation, in both WD-induced atherosclerosis and high-fat-induced obesity models. In addition, we found that DCA stimulated hepatic fibroblast growth factor 21 (Fgf21) mRNA expression, which might be important for lowering lipid levels and insulin sensitization via BAT activation, in a dose- and time-dependent manner associated with serum FGF21 levels. Interestingly, Fgf21 mRNA expression was mediated in an AMP-activated protein kinase (AMPK)-dependent manner within several minutes after DCA treatment independent of peroxisome proliferator-activated receptor alpha (PPARα). Taken together, the results suggest that enhanced glucose oxidation by DCA protects against atherosclerosis by inducing hepatic FGF21 expression and BAT activation, resulting in augmented energy expenditure for heat generation.

scholarly journals PGC-1α activator–induced fatty acid oxidation in tumor-infiltrating CTLs enhances effects of PD-1 blockade therapy in lung cancer

2019 ◽  
Vol 106 (1) ◽  
pp. 55-63
Author(s):  
Huan Wan ◽  
Bin Xu ◽  
Ni Zhu ◽  
Baozhong Ren
Keyword(s):  
Lung Cancer ◽  
Fatty Acid ◽  
Fatty Acid Oxidation ◽  
Tumor Model ◽  
Acid Oxidation ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Programmed Death ◽  
Effect Of Pd

Purpose: The present study aims to investigate the efficacy and mechanisms of peroxisome proliferator-activated receptor γ coactivator 1-α agonist, as adjuvant to programmed death-1 (PD-1) blockade in hyporesponsive lung cancer cells–derived in vivo tumor model, using bezafibrate. Methods: Mouse Lewis lung carcinoma (LLC) xenograft models were established and treated with programmed death-ligand 1 (PD-L1) monoclonal antibodies with or without bezafibrate. Tumors or peripheral blood of mice were harvested to investigate the quality, quantity, and function as well as energetic metabolism of cytotoxic T lymphocytes (CTLs) by flow cytometry or quantitative real-time polymerase chain reaction. Results: The combination of bezafibrate plus anti-PD-L1 reached synergistic tumoricidal effect in LLC xenograft mouse models, even though bezafibrate alone had no effect on tumor growth. Bezafibrate significantly facilitated CD8+ T cells infiltrating into tumor tissues by enhancing the expression of CXCL9 and CXCL10 within tumors as well as the receptor CXCR3 in infiltrating CTLs. Activated CTLs within tumors were also significantly upregulated by bezafibrate. Further data demonstrated that bezafibrate treatment could maintain the survival and functional capacity of tumor-infiltrating CTLs. Moreover, cellular reactive oxygen species in infiltrating CTLs and fatty acid oxidation (FAO)–related genes (PGC-1α, Cpt1a, and LCAD) expression within tumors were significantly increased after treatment with bezafibrate. Conclusions: Bezafibrate synergized the tumoricidal effect of PD-1 blockade in hyporesponsive lung cancer by expansion of effector CTLs within tumor microenvironment. The potential mechanism may relate to the capacity of bezafibrate in regulating FAO of tumor-infiltrating CTLs.

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.

Sign in / Sign up

Export Citation Format

Share Document