PPARalpha Activation Research Articles

#1144 Role of PPAR-alpha in folic acid-induced tubulointerstitial fibrosis

Abstract Background and Aims PPAR-alpha is a nuclear receptor that plays a major role in the regulation of lipid metabolism. Activation of PPAR-alpha has been shown to have beneficial effects in renal diseases. Acute kidney injury (AKI), even if followed by renal recovery, is a risk factor for the future development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Progressive tubulointerstitial fibrosis is the final common pathway for all kidney diseases leading to chronic renal failure. Our main objective was to determine the importance of PPAR-alpha in tubulointerstitial fibrosis in folic acid induced nephropathy. Method Male C57/Bl6 and PPARKO (C57Bl6 background) mice were divided into 4 groups, Control, Folic Acid, Gemfibrozil + Folic Acid and PPARKO + Folic Acid. Animals have been treated with a single dose of Folic Acid (250 mg/kg i.p) and Gemfibrozil (150 mg/kg gavage) euthanized after 28 days for. Renal parameters, histology, real time PCR were performed to investigate renal injury, inflammation, and fibrosis. Results After 28 days of folic acid inducing CKD. PPARKO showed the same levels of injury as folic acid alone treated mice, however PPAR-alpha activation with gemfibrozil decreased urinary volume (Folic Acid: 3.870 ± 0.679 Gemfibrozil: 1,242 ± 0,223), creatinine (Folic Acid: 0,7940 ± 0,0357 Gemfibrozil: 0,5820 ± 0,0288), urea levels (Folic Acid: 79,23 ± 3,20 Gemfibrozil: 46,11 ± 3,874), showed less tubulointerstitial fibrosis (Folic Acid: 0,5837 ± 0,0426), Gemfibrozil: 0,2423 ± 0,0293) and lower urine protein/creatinine ratio (Folic Acid: 5,486 ± 0,588 Gemfibrozil: 2,536 ± 0,127). Conclusion PPAR-alpha deletion did not show protection in chronic phase, in the other hand PPAR-alpha activation with gemfibrozil showed to be effective against tubulointerstitial fibrosis.

PPAR Alpha Activation by Clofibrate Alleviates Ischemia/Reperfusion Injury in Metabolic Syndrome Rats by Decreasing Cardiac Inflammation and Remodeling and by Regulating the Atrial Natriuretic Peptide Compensatory Response.

Metabolic syndrome (MetS) is a cluster of factors that increase the risk of developing diabetes, stroke, and heart failure. The pathophysiology of injury by ischemia/reperfusion (I/R) is highly complex and the inflammatory condition plays an important role by increasing matrix remodeling and cardiac apoptosis. Natriuretic peptides (NPs) are cardiac hormones with numerous beneficial effects mainly mediated by a cell surface receptor named atrial natriuretic peptide receptor (ANPr). Although NPs are powerful clinical markers of cardiac failure, their role in I/R is still controversial. Peroxisome proliferator-activated receptor α agonists exert cardiovascular therapeutic actions; however, their effect on the NPs' signaling pathway has not been extensively studied. Our study provides important insight into the regulation of both ANP and ANPr in the hearts of MetS rats and their association with the inflammatory conditions caused by damage from I/R. Moreover, we show that pre-treatment with clofibrate was able to decrease the inflammatory response that, in turn, decreases myocardial fibrosis, the expression of metalloprotease 2 and apoptosis. Treatment with clofibrate is also associated with a decrease in ANP and ANPr expression.

Terpene-Containing Analogues of Glitazars as Potential Therapeutic Agents for Metabolic Syndrome.

Metabolic syndrome is a complex of abnormalities involving impaired glucose and lipid metabolism, which needs effective pharmacotherapy. One way to reduce lipid and glucose levels associated with this pathology is the simultaneous activation of nuclear PPAR-alpha and gamma. For this purpose, we synthesized a number of potential agonists based on the pharmacophore fragment of glitazars with the inclusion of mono- or diterpenic moiety in the molecular structure. The study of their pharmacological activity in mice with obesity and type 2 diabetes mellitus (C57Bl/6Ay) revealed one substance that was capable of reducing the triglyceride levels in the liver and adipose tissue of mice by enhancing their catabolism and expressing a hypoglycemic effect connected with the sensitization of mice tissue to insulin. It has also been shown to have no toxic effects on the liver.

Role of lysosomal acid lipase in PPAR-mediated reduction of lipid accumulation in hepatocytes

Background and Aims : Lysosomal acid lipase (LAL) catalyzes the hydrolysis of cholesteryl esters and triglycerides in the lysosomal compartment. Recently, it was shown that NAFLD patients can develop an acquired LAL deficiency which is rescued by PPAR-alpha activation. Aim of the study was to investigate the role of other isoform-specific and dual PPAR agonists on lipid accumulation and LAL activity using an in vitro model of steatosis.

SAT055 - The ubiquitin-like modifier FAT10 is upregulated during NASH and impairs PPAR-alpha activity

SAT055 - The ubiquitin-like modifier FAT10 is upregulated during NASH and impairs PPAR-alpha activity

Peroxisome proliferator-activated receptor-alpha activation and dipeptidyl peptidase-4 inhibition target dysbiosis to treat fatty liver in obese mice.

BACKGROUNDObesity and comorbidities onset encompass gut dysbiosis, altered intestinal permeability, and endotoxemia. Treatments that target gut dysbiosis can cope with obesity and nonalcoholic fatty liver disease (NAFLD) management. Peroxisome proliferator-activated receptor (PPAR)-alpha activation and dipeptidyl-peptidase-4 (DPP-4) inhibition alleviate NAFLD, but the mechanism may involve gut microbiota modulation and merits further investigation. AIMTo address the effects of PPAR-alpha activation and DPP-4 inhibition (isolated or combined) upon the gut-liver axis, emphasizing inflammatory pathways in NAFLD management in high-fat-fed C57BL/6J mice. METHODSMale C57BL/6J mice were fed a control diet (C, 10% of energy as lipids) or a high-fat diet (HFD, 50% of energy as lipids) for 12 wk, when treatments started, forming the groups: C, HF, HFA (HFD + PPAR-alpha agonist WY14643, 2.5 mg/kg body mass), HFL (HFD + DPP-4 inhibitor linagliptin, 15 mg/kg body mass), and HFC (HFD + the combination of WY14643 and linagliptin). RESULTSThe HFD was obesogenic compared to the C diet. All treatments elicited significant body mass loss, and the HFC group showed similar body mass to the C group. All treatments tackled oral glucose intolerance and raised plasma glucagon-like peptide-1 concentrations. These metabolic benefits restored Bacteroidetes/Firmicutes ratio, resulting in increased goblet cells per area of the large intestine and reduced lipopolysaccharides concentrations in treated groups. At the gene level, treated groups showed higher intestinal Mucin 2, Occludin, and Zo-1 expression than the HFD group. The reduced endotoxemia suppressed inflammasome and macrophage gene expression in the liver of treated animals. These observations complied with the mitigation of liver steatosis and reduced hepatic triacylglycerol, reassuring the role of the proposed treatments on NAFLD mitigation.CONCLUSIONPPAR alpha activation and DPP-4 inhibition (isolated or combined) tackled NAFLD in diet-induced obese mice by restoration of gut-liver axis. The reestablishment of the intestinal barrier and the rescued phylogenetic gut bacteria distribution mitigated liver steatosis through anti-inflammatory signals. These results can cope with NAFLD management by providing pre-clinical evidence that drugs used to treat obesity comorbidities can help to alleviate this silent and harmful liver disease.

Nonclassical Axis of the Renin-Angiotensin System and Neprilysin: Key Mediators That Underlie the Cardioprotective Effect of PPAR-Alpha Activation during Myocardial Ischemia in a Metabolic Syndrome Model.

The activation of the renin-angiotensin system (RAS) participates in the development of metabolic syndrome (MetS) and in heart failure. PPAR-alpha activation by fenofibrate reverts some of the effects caused by these pathologies. Recently, nonclassical RAS components have been implicated in the pathogenesis of hypertension and myocardial dysfunction; however, their cardiac functions are still controversial. We evaluated if the nonclassical RAS signaling pathways, directed by angiotensin III and angiotensin-(1-7), are involved in the cardioprotective effect of fenofibrate during ischemia in MetS rats. Control (CT) and MetS rats were divided into the following groups: (a) sham, (b) vehicle-treated myocardial infarction (MI-V), and (c) fenofibrate-treated myocardial infarction (MI-F). Angiotensin III and angiotensin IV levels and insulin increased the aminopeptidase (IRAP) expression and decreased the angiotensin-converting enzyme 2 (ACE2) expression in the hearts from MetS rats. Ischemia activated the angiotensin-converting enzyme (ACE)/angiotensin II/angiotensin receptor 1 (AT1R) and angiotensin III/angiotensin IV/angiotensin receptor 4 (AT4R)-IRAP axes. Fenofibrate treatment prevented the damage due to ischemia in MetS rats by favoring the angiotensin-(1-7)/angiotensin receptor 2 (AT2R) axis and inhibiting the angiotensin III/angiotensin IV/AT4R-IRAP signaling pathway. Additionally, fenofibrate downregulated neprilysin expression and increased bradykinin production. These effects of PPAR-alpha activation were accompanied by a reduction in the size of the myocardial infarct and in the activity of serum creatine kinase. Thus, the regulation of the nonclassical axis of RAS forms part of a novel protective effect of fenofibrate in myocardial ischemia.

Branched-Chain Fatty Acids as Mediators of the Activation of Hepatic Peroxisome Proliferator-Activated Receptor Alpha by a Fungal Lipid Extract.

The study aimed to test the hypothesis that monomethyl branched-chain fatty acids (BCFAs) and a lipid extract of Conidiobolus heterosporus (CHLE), rich in monomethyl BCFAs, are able to activate the nuclear transcription factor peroxisome proliferator-activated receptor alpha (PPARalpha). Rat Fao cells were incubated with the monomethyl BCFAs 12-methyltridecanoic acid (MTriA), 12-methyltetradecanoic acid (MTA), isopalmitic acid (IPA) and 14-methylhexadecanoic acid (MHD), and the direct activation of PPARalpha was evaluated by reporter gene assay using a PPARalpha responsive reporter gene. Furthermore, Fao cells were incubated with different concentrations of the CHLE and PPARalpha activation was also evaluated by using the reporter gene assay, and by determining the mRNA concentrations of selected PPARalpha target genes by real-time RT-PCR. The reporter gene assay revealed that IPA and the CHLE, but not MTriA, MHD and MTA, activate the PPARalpha responsive reporter gene. CHLE dose-dependently increased mRNA concentrations of the PPARalpha target genes acyl-CoA oxidase (ACOX1), cytochrome P450 4A1 (CYP4A1), carnitine palmitoyltransferase 1A (CPT1A) and solute carrier family 22 (organic cation/carnitine transporter), member 5 (SLC22A5). In conclusion, the monomethyl BCFA IPA is a potent PPARalpha activator. CHLE activates PPARalpha-dependent gene expression in Fao cells, an effect that is possibly mediated by IPA.

Abstract 412: DJ-1 Deficiency Impairs Post-Ischemic Cardiac Fatty Acid Oxidation

Background: DJ-1 is a cytoprotective protein implicated in many cellular processes. We have recently shown that DJ-1 plays a protective role in the setting of acute myocardial ischemia-reperfusion injury and heart failure. However, specific mechanisms of action remain unknown. Here, we sought to determine if DJ-1 maintains fatty acid oxidation following myocardial I/R injury via the regulation of PPARalpha transcriptional activity. Methods and Results: WT and DJ-1 KO hearts were subjected to 45 minutes of ischemia via coronary artery ligation followed by up to 72 hours of reperfusion. Initial studies revealed that PPARalpha activity (PPARalpha Transcription Factor Assay Kit; abcam) was lower in DJ-1 KO hearts under both basal (sham) and I/R conditions. Next, we performed an analysis of PPAR genes using a qPCR array (Mouse PPAR Targets RT2 Profiler PCR Array from Qiagen) that profiled the expression of 84 key genes involved in PPAR activation and response. Marked differences in genes involved in FA metabolism were evident in the hearts of DJ-1 KO mice. Further studies using qPCR validated a significant decrease in the expression of acsl1 (protein ACSL1), acsl3, acsl5, cpt1b (protein CPT1), slc25a20 (protein CACT), and cpt2. The protein expression of ACSL1, CPT1, and CACT were also decreased in the hearts of DJ-1 KO mice following I/R injury. These changes were accompanied by higher cardiac lipid content and depressed mitochondrial fatty-acid β-oxidation and ATP synthesis. Conclusion: These data demonstrate that DJ-1 plays an essential role in regulating post-I/R cardiac FAO. Future studies will garner mechanistic insight for the impaired function of PPARalpha with the loss of DJ-1.

Gut-liver axis modulation in fructose-fed mice: a role for PPAR-alpha and linagliptin.

Fructose dietary intake affects the composition of the intestinal microbiota and influences the development of hepatic steatosis. Endotoxins produced by gram-negative bacteria alter intestinal permeability and cause bacterial translocation. This study evaluated the effects of gut microbiota modulation by a purified PPAR-alpha agonist (WY14643), a DPP-4 inhibitor (linagliptin), or their association on intestinal barrier integrity, endotoxemia, and hepatic energy metabolism in high-fructose-fed C57BL/6 mice. Fifty mice were divided to receive the control diet (C group) or the high-fructose diet (HFRU) for 12 weeks. Subsequently, the HFRU group was divided to initiate the treatment with PPAR-alpha agonist (3.5 mg/kg/BM) and DPP-4 inhibitor (15 mg/kg/BM). The HFRU group had glucose intolerance, endotoxemia, and dysbiosis (with increased Proteobacteria) without changes in body mass in comparison with the C group. HFRU group showed damaged intestinal ultrastructure, which led to liver inflammation and marked hepatic steatosis in the HFRU group when compared to the C group. PPAR-alpha activation and DPP-4 inhibition countered glucose intolerance, endotoxemia, and dysbiosis, ameliorating the ultrastructure of the intestinal barrier and reducing Tlr4 expression in the liver of treated animals. These beneficial effects suppressed lipogenesis and mitigated hepatic steatosis. In conclusion, the results herein propose a role for PPAR-alpha activation, DPP-4 inhibition, and their association in attenuating hepatic steatosis by gut-liver axis modulation in high-fructose mice model. These observations suggest these treatments as potential targets to treat hepatic steatosis and avoid its progression.

P0123THE IMPORTANCE OF PPAR-ALPHA IN AKI TO CKD TRANSITION IN NEPHROPATHY INDUCED BY FOLIC ACID

Abstract Background and Aims PPAR-alpha is a nuclear receptor which plays major role in the regulation of lipid metabolism, activation of PPAR-alpha has been shown to have beneficial effects in renal diseases. Acute kidney injury (AKI), even if followed by renal recovery, is a risk factor for the future development of chronic kidney disease (CKD) and end-stage renal disease (ESRD). Our main objective was to determine the importance of PPAR-alpha in AKI to CKD transition in folic acid induced nephropathy. Method Male C57/Bl6 and PPARKO (C57Bl6 background) mice were divided in 4 groups, Control, Folic Acid, Gemfibrozil + Folic Acid and PPARKO + Folic Acid. Animals has been treated with single dose of Folic Acid (250mg/kg i.p) and Gemfibrozil (150mg/kg gavage) euthanized after 48 hours for AKI assessment and 28 days for CKD. Renal parameters, histology, real time PCR were performed to investigate renal injury, inflammation and fibrosis. Results After 48 hours of folic acid inducing AKI, PPARKO mice showed decreased urea levels (Folic Acid: 178,9±25,2 PPARKO: 92,4±15,5), less tubular injury (Folic Acid: 0,61±0,05 PPARKO: 0,21±0,03), lower mRNA expression of NGAL (Folic Acid; 32,2±7,67 PPARKO 3,74±1,71), KIM-1 (Folic Acid: 671,8±170,2 PPARKO: 43,4±29,7) and TNF-alpha (Folic Acid: 2,81±0,58 PPARKO: 0,67±0,14), while PPAR-alpha activation with gemfibrozil showed to have no effects in AKI. After 28 days of folic acid inducing CKD. PPARKO showed same levels of injury than folic acid alone treated mice, however PPAR-alpha activation with gemfibrozil decreased urea levels (Folic Acid: 79,2±3,2 Gemfibrozil: 46,1±3,8), showed less tubulointerstitial fibrosis (Folic Acid: 0,60±0,05 Gemfibrozil: 0,18±0,02) and lower urine protein/creatinine ratio (Folic Acid: 5,48±0,58 Gemfibrozil: 2,53±0,12), Conclusion PPAR-alpha deletion protects against AKI induced by folic acid but did not showed protection in chronic phase, in the other hand ppar-alpha activation with gemfibrozil did not protect in AKI but show to be effective in CKD.

Lipid accumulation impairs lysosomal acid lipase activity in hepatocytes: Evidence in NAFLD patients and cell cultures

AimsIt has been hypothesized that the activity of lysosomal acid lipase (LAL), a key enzyme involved in lipid metabolism, is involved in the NAFLD phenotype. To clarify the role of LAL in NAFLD, we studied 164 consecutive patients with biopsy-proven NAFLD and fat-loaded HepG2 cells. MethodsLAL activity was measured (i) on dried blood spots (DBS) from NAFLD patients and dyslipidemic subjects without fatty liver and (ii) on liver biopsies from NAFLD patients. LAL activity and expression were evaluated in HepG2 cells cultured in the presence of free fatty acids (FAs), with or without a PPAR-alpha agonist. ResultsLAL activity was significantly reduced in patients with NAFLD compared to dyslipidemic subjects. LAL activity measured in liver biopsies from NAFLD patients was highly correlated to that measured on DBS and was independent of LAL expression in the liver. In a fully adjusted model, LAL activity on DBS was associated only with platelets and, when normalized by platelet count, it did not differ according to fibrosis stage. In vitro, FA loading of HepG2 fully replicated the impairment of LAL activity observed in NALFD patients. In these cells, the activation of PPAR-alpha receptors prevented and corrected FA-induced LAL impairment, by stimulating FA oxidation and LAL expression. ConclusionsLAL activity is reduced in NAFLD patients, independently from disease progression. In vitro, impaired LAL activity induced by FA loading was rescued by PPAR-alpha activation. These data suggest that the pharmacological modulation of LAL should be explored in the management of NAFLD patients.

Soluble Epoxide Hydrolase Inhibitor t-AUCB Promotes Murine Brown Adipogenesis: Role of PPAR Gamma and PPAR Alpha (P21-069-19)

ObjectivesBrown adipose tissue has recently emerged as a novel target for obesity treatment and prevention. In contrast to the lipid storing function of white adipocytes, brown adipocytes are responsible for dissipating energy as heat, a process involving uncoupling protein 1 (UCP1). Soluble epoxide hydrolase (sEH) is a cytosolic enzyme that converts epoxy fatty acids (EpFAs) into less active diols. By stabilizing endogenous EpFAs, potent small molecule sEH inhibitors have been shown to be beneficial for many chronic diseases. Several recent papers have reported that sEH inhibitors are able to reduce diet-induced obesity, possibly by upregulating UCP1 expression. In the current study, we sought to study the mechanisms by which sEH inhibitor acts on brown preadipocytes. MethodsThe effects of a potent sEH inhibitor, trans-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB), on murine brown adipocyte differentiation were evaluated by lipid accumulation and expression of brown adipocyte marker genes. PPAR alpha and PPAR gamma activation by t-AUCB was measured by their respective transactivation assays. The roles of PPARs were further studied by pharmacological antagonism and knockdown experiments by small RNA interference. ResultsWe report that sEH expression was increased during murine brown adipocyte differentiation. t-AUCB dose-dependently promoted brown adipocyte differentiation. Moreover, we demonstrate that t-AUCB activated PPAR alpha, but not PPAR gamma. t-AUCB-induced upregulation of thermogenic gene Ucp1 and Pgc1 alpha and the general differentiation marker Fabp4 were significantly attenuated by the antagonist of PPAR alpha, GW6471. In contrast, they were only partially attenuated by the antagonist of PPAR gamma, GW9662, and specific knockdown of PPAR gamma. ConclusionsOur findings suggest that sEH may regulate brown adipogenesis and sEH pharmacological inhibition by t-AUCB promotes brown adipogenesis, possibly through activation of PPAR alpha. Funding SourcesThe work is supported by NIH 1R15DK114790-01A1 (to LZ), R00DK100736 (to AB) and R01ES002710 (to BDH).

189-LB: Maternal Pharmacological Activation of PPAR-gamma or PPAR-alpha Differentially Affects Adiposity and Energy Metabolism in the Offspring of Rats Born to Mothers Subjected to Caloric Restriction during Pregnancy

Aims: Rats born to mothers subjected to caloric restriction (CR) during pregnancy and lactation exhibit reduced birth weight and adiposity in adult life. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that play important roles in adipocytes differentiation. The aim of our study is to evaluate if antenatal exposition PPAR-gamma (Pioglitazone) or PPAR-alpha (Gemfibrozil) activators are able to affect energy metabolism in the offspring born from rats subjected to RC during pregnancy and lactation. Methods: Wistar rats were kept under CR from the 11th day of pregnancy until the 21st day after delivery. Pioglitazone (10mg/kg) or Gemfibrozil (90mg/kg) were offered during the period of CR (offspring were CR+Pio and CR+Gem, respectively). Adult female offspring were subjected to indirect calorimetry, thermal infra-red imaging of BAT, VLDL production assay and DEXA for body composition. Results: The body weight in adult CR+Gem, but not in CR+Pio, was higher than that of offspring born to CR mother. CR+Pio had reduced energy expenditure (EE) and higher relative weight of the perigonadal and retroperitoneal fat pads. On the other hand, adult CR+Gem had no changes in EE and visceral adiposity when compared to RC but presented increased whole-body adiposity as revealed by DEXA analysis. Although hepatic triglycerides (TG) or VLDL production were not altered in offspring born to CR mothers and in CR+Pio, these parameters were downregulated in RC+Gem. Both RC+Pio and RC+Gem had reduced temperature of the interscapular brown adipose tissue when compared to CR. Conclusion: Maternal activation of PPAR-gamma increases visceral adiposity and reduces EE in the offspring born to mothers subjected to CR during pregnancy. Maternal activation of PPAR-alpha instead, increased body weight and reduced hepatic steatosis of the offspring born to mother exposed to CR. Disclosure V.B. Veronesi: None. J.C. Santos-Silva: None. D.N. Souza: None. C.J. Teixeira: None. F.B. Hecht: None. N. Tobar: None. M. Rodrigues Pioli: None. G.F. Anhe: None. Funding Funda??o de Amparo ? Pesquisa do Estado de S?o Paulo

Anti-obesogenic effects of WY14643 (PPAR-alpha agonist): Hepatic mitochondrial enhancement and suppressed lipogenic pathway in diet-induced obese mice

Non-alcoholic fatty liver disease (NAFLD) presents with growing prevalence worldwide, though its pharmacological treatment remains to be established. This study aimed to evaluate the effects of a PPAR-alpha agonist on liver tissue structure, ultrastructure, and metabolism, focusing on gene and protein expression of de novo lipogenesis and gluconeogenesis pathways, in diet-induced obese mice. Male C57BL/6 mice (three months old) received a control diet (C, 10% of lipids, n = 10) or a high-fat diet (HFD, 50% of lipids, n = 10) for ten weeks. These groups were subdivided to receive the treatment (n = 5 per group): C, C-alpha (PPAR-alpha agonist, 2.5 mg/kg/day mixed in the control diet), HFD and HFD-alpha group (PPAR-alpha agonist, 2.5 mg/kg/day mixed in the HFD). The effects were compared with biometrical, biochemical, molecular biology and transmission electron microscopy (TEM) analyses. HFD showed greater body mass (BM) and insulinemia than C, both of which were tackled by the treatment in the HFD-alpha group. Increased hepatic protein expression of glucose-6-phosphatase, CHREBP and gene expression of PEPCK in HFD points to increased gluconeogenesis. Treatment rescued these parameters in the HFD-alpha group, eliciting a reduced hepatic glucose output, confirmed by the smaller GLUT2 expression in HFD-alpha than in HFD. Conversely, favored de novo lipogenesis was found in the HFD group by the increased expression of PPAR-gamma, and its target gene SREBP-1, FAS and GK when compared to C. The treatment yielded a marked reduction in the expression of all lipogenic factors. TEM analyses showed a greater numerical density of mitochondria per area of tissue in treated than in untreated groups, suggesting an increase in beta-oxidation and the consequent NAFLD control. PPAR-alpha activation reduced BM and treated insulin resistance (IR) and NAFLD by increasing the number of mitochondria and reducing hepatic gluconeogenesis and de novo lipogenesis protein and gene expressions in a murine obesity model.

Artificial Zinc-Finger Transcription Factor of A20 Suppresses Restenosis in Sprague Dawley Rats after Carotid Injury via the PPARα Pathway.

The inhibition of inflammation and vascular smooth muscle cell (VSMC) proliferation is an ideal strategy to suppress intimal hyperplasia after percutaneous transluminal angioplasty (PTA). Evidence has indicated that overexpression of A20 suppresses neointima formation, but its low transfection efficiency limits its application. Hence, we upregulated A20 expression via transfection of rAd.ATF (recombinant adenovirus vector of artificial transcription factor) and rAd.A20 in rat carotid arteries after balloon dilatation (in vivo) and isolated VSMCs (in vitro). In vivo, we found that after rAd.ATF and rAd.A20 transfection, A20 expression was markedly increased, whereas proliferating cell nuclear antigen (PCNA) and nuclear factor κB p65 (NF-κBp65) protein levels were significantly decreased, and intimal hyperplasia and secretion of proinflammatory factors were significantly reduced when compared with empty vector and saline control groups. Most importantly, the rAd.ATF-treated group showed more significant inhibition on intimal hyperplasia and expression of PCNA than the rAd.A20-treated group. In vitro, compared with the control group, transfection of rAd.ATF and rAd.A20 significantly increased A20 expression, which upregulated the proliferator-activated receptor (PPAR) level for both mRNA and protein, and reduced migration and proliferation of VSMCs and lipopolysaccharide (LPS)-induced inflammation. Furthermore, the PPARα agonist GW6471 could partially restore the effect of A20 on VSMCs. Our findings indicate that the ATF of A20 inhibits neointimal hyperplasia and, therefore, constitutes a novel potential alternative to prevent restenosis.

Link Between ER-Stress, PPAR-Alpha Activation, and BET Inhibition in Relation to Apolipoprotein A-I Transcription in HepG2 Cells.

Activating transcription factor peroxisome proliferator-activated receptor alpha (PPARα) may increase apoA-I transcription. Furthermore, Bromodomain and Extra-Terminal domain (BET) protein inhibitors increase, whereas Endoplasmic Reticulum (ER) stress decreases apoA-I transcription. We examined possible links between these processes as related to apoA-I transcription in HepG2 cells. JQ1(+), thapsigargin, and GW7647 were used to induce, respectively BET inhibition, ER-stress, and PPARα activation. Expression of ER-stress markers (CHOP, XBP1s) was analyzed by western blotting. PPARα, KEAP1 (marker for BET inhibition), and apoA-I mRNAs were measured using qPCR. ER-stress and BET inhibition both decreased PPARα mRNA expression and activity, but did not interfere with each other, as ER-stress did not change KEAP1 and JQ1(+) did not influence ER-stress marker production. Interestingly, PPARα activation and BET-inhibition diminished ER-stress marker production and rescued apoA-I transcription during existing ER-stress. We conclude that the ER-stress mediated reduction in apoA-I transcription could be partly mediated via the inhibition of PPARα mRNA expression and activity. In addition, BET inhibition increased apoA-I transcription, even if PPARα production and activity were decreased. Finally, both BET inhibition and PPARα activation ameliorate the apoA-I lowering effect of ER-stress and are therefore interesting targets to elevate apoA-I transcription. J. Cell. Biochem. 118:2161-2167, 2017. © 2016 Wiley Periodicals, Inc.

Muscle Ring Finger‐1 Knockout (MuRF1−/−) Mice are Resistant to LPS‐induced Cardiac Dysfunction Due to Decreased NF‐κB Activity

Sepsis is associated with a high mortality (up to 40%) in hospitalized patients. Cardiac dysfunction plays a critical role in the outcome of severe sepsis, and sepsis‐targeted cardiac therapies are lacking. Fortunately, recent studies have identified the role of Toll‐like receptors, cytokines, and NF‐kappaB signaling in sepsis‐associated heart failure. We recently identified that the muscle‐specific ubiquitin ligase MuRF1 (Muscle Ring Finger1) inhibits peroxisome proliferator‐activated receptor alpha (PPARalpha) in cardiomyocytes by mediating its nuclear export in a ubiquitin‐dependent manner. We found that MuRF1 interacts with PPARalpha to mediate a multi‐monoubiquitination using three lysines surrounding a newly identified nuclear export sequence. Interestingly, MuRF1−/− mice have a five‐fold increase in cardiac PPARalpha activity. Since studies have shown that PPARalpha competitively inhibits NF‐kappaB and downstream inflammation, we hypothesized that MuRF1−/− mice would exhibit cardiomyocyte anti‐inflammatory responses through its competitive increase in PPARalpha activity. To test this, we performed echocardiography on MuRF1−/− and wildtype mice at baseline and 4, 24, 48, and 72 hours post‐lipopolysaccharide injection (2 mg/kg of LPS). LPS interacts with Toll‐like receptor 4 on cardiomyocytes and inflammatory cells, releasing cardiodepressant cytokines (e.g. TNFa, IL‐1, IL‐6) that activate NF‐kappaB. No mice died during the course of the 72 hour study and no cardiac differences were observed between groups at baseline. Four hours after LPS, wildtype mice exhibited significantly worse systolic function compared to MuRF1−/− mice (Fractional Shortening (FS)%=34.5+1.5 vs. 42.0+4.5). Wildtype LPS treated hearts exhibited significant wall thinning, while MuRF1−/− wall thickness did not change from baseline. MuRF1−/− LPS‐induced cardiac dysfunction was completely resolved by 72 hours (FS%=57.5+1.4), whereas wildtype hearts still exhibited residual dysfunction (FS%=48.4+1.9). Analysis by immunoblot (from hearts harvested 72 hours post LPS treatment) showed (active) P‐Ikappa Balpha was decreased in MuRF1−/− mice, indicating NF‐kB signaling was decreased in these mice. Similarly, inflammatory cytokine markers IL‐1alpha and IL‐1beta were decreased in MuRF1−/− mice, indicating MuRF1−/− mice had less inflammation. These data are in step with our hypothesis, demonstrating that MuRF1's regulation of PPARalpha may affect the heart's ability to respond to NF‐kappaB (due to enhanced nuclear PPARalpha activity inhibiting NF‐kappaB signaling). Therapeutic inhibition of the MuRF1‐PPARalpha interaction provides a muscle‐specific therapy that may prove beneficial in NF‐kappaB‐mediated cardiac dysfunction seen in sepsis, heart failure, and myocardial infarction.

Caloric Restriction Is More Efficient than Physical Exercise to Protect from Cisplatin Nephrotoxicity via PPAR-Alpha Activation.

The antineoplastic drug cisplatin promotes renal injury, which limits its use. Protocols that reduce renal cisplatin toxicity will allow higher doses to be used in cisplatin treatment. Here, we compare physical exercise and caloric restriction (CR) as protocols to reduce cisplatin renal injury in mice. Male C57BL/6 were divided into four groups: Control, cisplatin, exercise + cisplatin, and 30% CR + cisplatin. Animals were injected with a single dose of cisplatin (20 mg/kg i.p.) and sacrificed 96 h after injection. Quantitative real time PCR, histological analyses, immunohistochemistry, and biochemical measurements were performed to investigate renal injury, necrosis, apoptosis, and inflammatory mechanisms. Both protocols protected against cisplatin renal injury, but CR was more effective in reducing uraemia and renal necrosis. The CR + Cisplatin group exhibited reduced serum IL-1β and TNF-α levels. No differences were noted in the renal mRNA expression of cytokines. Both interventions reduced apoptosis, but only the CR + Cisplatin group decreased TNFR2 protein expression. PPAR-α was activated in mice after CR. An antagonist of PPAR-α blocked the protective effect of CR. Both interventions attenuated the nephrotoxicity caused by cisplatin injection, but CR + Cisplatin showed a better response by modulating TNFR2. Moreover, part of the CR benefit depends on PPAR-α activation.

Increased apoA-I transcription by bet inhibitor JQ1(+) acts independently from PPAR-alpha activation and is linked to ER-stress inhibition

Increased apoA-I transcription by bet inhibitor JQ1(+) acts independently from PPAR-alpha activation and is linked to ER-stress inhibition