Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UMLS:C0242339 (dyslipidemia)
13,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Peroxisome proliferator-activated receptor alpha (PPARalpha) regulates the utilization of fat as an energy source during starvation and is the molecular target for the fibrate dyslipidemia drugs. Here, we identify the endocrine hormone fibroblast growth factor 21 (FGF21) as a mediator of the pleiotropic actions of PPARalpha. FGF21 is induced directly by PPARalpha in liver in response to fasting and PPARalpha agonists. FGF21 in turn stimulates lipolysis in white adipose tissue and ketogenesis in liver. FGF21 also reduces physical activity and promotes torpor, a short-term hibernation-like state of regulated hypothermia that conserves energy. These findings demonstrate an unexpected role for the PPARalpha-FGF21 endocrine signaling pathway in regulating diverse metabolic and behavioral aspects of the adaptive response to starvation.
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PMID:Endocrine regulation of the fasting response by PPARalpha-mediated induction of fibroblast growth factor 21. 1755 Jul 73

Dyslipidemia is defined by abnormal levels of plasma lipoproteins. Several different types of dyslipidemia can be distinguished. An important group of drugs used in the treatment of dyslipidemia are the fibrates. Fibrates serve as agonists for the peroxisome proliferator-activated receptor alpha (PPARalpha), a ligand-activated transcription factor that belongs to the superfamily of nuclear hormone receptors. By binding to response elements mostly present in the promoter of target genes, PPARalpha governs the expression of numerous genes involved in a variety of metabolic processes. Activation of PPARalpha results in a reduction of plasma TG levels, which is achieved by: (1) induction of genes that decrease the availability of TG for hepatic VLDL secretion, and (2) induction of genes that promote lipoprotein lipase-mediated lipolysis of TG-rich plasma lipoproteins. The stimulatory effect of PPARalpha on plasma HDL levels in humans, which is opposite to what is observed in mice, appears to be mainly mediated via increased production of APOA1 and APOA2, the apolipoprotein constituents of HDL. Apart from its major actions outlined above, PPARalpha modulates lipoprotein metabolism in several other ways, mostly via direct up-regulation of specific PPARalpha target genes. By taking into account novel insights into the metabolism of plasma lipoproteins and by considering the latest information on PPARalpha-dependent gene regulation, a fresh perspective on the molecular mechanisms underlying the plasma lipoprotein modulating effect of PPARalpha is presented.
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PMID:PPARalpha and dyslipidemia. 1760 18

Tesaglitazar (GALIDA; AstraZeneca, Wilmington, DE) is a dual peroxisome proliferator-activated receptor alpha/gamma agonist previously in clinical development for the treatment of glucose and lipid abnormalities associated with type 2 diabetes mellitus and insulin resistance. This study compared the efficacy of tesaglitazar with that of pioglitazone as adjunctive therapy to atorvastatin in subjects with abdominal obesity and dyslipidemia. In this open-label, 3-way crossover study, 58 subjects received atorvastatin 10 mg once daily in a 6-week run-in period, followed by tesaglitazar 3 mg, pioglitazone 45 mg, or placebo, as adjunctive therapy to atorvastatin, in a randomized sequence for 6 weeks each. Serum triglycerides and other lipids, apolipoproteins, glucose, and insulin concentrations were compared between treatments. Tesaglitazar adjunctive therapy reduced serum triglycerides significantly more from baseline (-1.07 mmol/L) than pioglitazone (-0.33 mmol/L; P = .007) or placebo (-0.09 mmol/L; P < .0001). Tesaglitazar also resulted in significantly greater improvements in free fatty acids, very low-density lipoprotein cholesterol, low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio, low-density lipoprotein particle size, apolipoprotein (apo) B, apo C-III, and the apo B/apo A-I ratio compared with pioglitazone or placebo. Tesaglitazar adjunctive therapy also reduced fasting plasma glucose, fasting plasma insulin, and insulin resistance (homeostasis model assessment index) significantly more than pioglitazone or placebo (P < .0001 for all comparisons). Tesaglitazar was generally well tolerated in combination with atorvastatin, but hemoglobin and absolute neutrophil count decreased and serum creatinine increased more with tesaglitazar than with pioglitazone or placebo. These effects, also shown in previous trials, led to the discontinuation of the clinical development of the drug. In conclusion, the addition of tesaglitazar to a background of atorvastatin therapy further improved the dyslipidemia associated with insulin resistance.
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PMID:The dual peroxisome proliferator-activated receptor alpha/gamma agonist tesaglitazar further improves the lipid profile in dyslipidemic subjects treated with atorvastatin. 1769 74

Peroxisome proliferator-activated receptor alpha (PPARalpha) is a key regulator in hepatic lipid metabolism and a potential therapeutic target for dyslipidemia. However, in humans hepatic PPARalpha-regulated genes remain unclear. To investigate the effect of PPARalpha agonism on mRNA expressions of lipid metabolism-related genes in human livers, a potent PPARalpha agonist, KRP-101 (KRP), was used to treat the human hepatoma cell line, HepaRG cells. KRP did not affect AOX or L-PBE, which are involved in peroxisomal beta-oxidation. KRP increased L-FABP, CPT1A, VLCAD, and PDK4, which are involved in lipid transport or oxidation. However, the EC(50) values (114-2500 nM) were >10-fold weaker than the EC(50) value (10.9 nM) for human PPARalpha in a transactivation assay. To search for more sensitive genes, we determined the mRNA levels of apolipoproteins, apoA-I, apoA-II, apoA-IV, apoA-V, and apoC-III. KRP had no or little effect on apoA-I, apoC-III, and apoA-II. Interestingly, KRP increased apoA-IV (EC(50), 0.99 nM) and apoA-V (EC(50), 0.29 nM) with high sensitivity. We identified apoA-IV as a PPARalpha-upregulated gene in a study using PPARalpha siRNA. Moreover, when administered orally to dogs, KRP decreased the serum triglyceride level and increased the serum apoA-IV level in a dose-dependent manner. These findings suggest that apoA-IV, newly identified as a highly sensitive PPARalpha-regulated gene in human livers, may be one of the mechanisms underlying PPARalpha agonist-induced triglyceride decrease and HDL elevation.
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PMID:Highly sensitive upregulation of apolipoprotein A-IV by peroxisome proliferator-activated receptor alpha (PPARalpha) agonist in human hepatoma cells. 1790 33

Non-alcoholic steatohepatitis (NASH) is a hepatic manifestation of the metabolic syndrome that can progress to liver cirrhosis. The major aim of this study was to establish a novel NASH mouse model accompanied by obesity and insulin resistance, then explore the molecular mechanisms of NASH and evaluate the effects of both the peroxisome proliferator-activated receptor alpha (PPARalpha) agonist fenofibrate and the PPARgamma agonist rosiglitazone in this established NASH model. The novel model was induced in C57BL/6 mice by 23 weeks of ad libitum feeding of a modified high-fat diet (mHFD), with lower methinione and choline and higher fat content. In comparison to the controls, the model animals developed pronounced obesity, dyslipidemia and insulin resistance. Marked liver lesions characterized by severe steatosis, inflammation, fibrosis, increased hepatic triglyceride content, and elevated serum alanine aminotransferase (ALT) levels were observed in the models. In this novel model, treatment with fenofibrate or rosiglitazone significantly improved insulin sensitivity and corrected dyslipidemia; however, fenofibrate was more effective than rosiglitazone in improving hepatic morphology and ALT levels. Further study showed that long-term feeding of mHFD significantly increased expression of mRNA for hepatic PPARgamma, adipose fatty acid binding protein (ap2) and CD36 and suppressed expression of mRNA for hepatic PPARalpha and carnitine palmitoyl transferase-1a (CPT-1a). These results showed the successful establishment of the combined NASH and obese-insulin resistance mouse model. Additionally, aberrant expressions of hepatic PPARalpha and PPARgamma may play a major role in the pathogenesis of NASH by affecting hepatic lipogenesis and fatty acid oxidation in this novel model.
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PMID:The establishment of a novel non-alcoholic steatohepatitis model accompanied with obesity and insulin resistance in mice. 1841 55

Although a change in lifestyle is the first choice in controlling cardiovascular risk, lipid-lowering drugs are effective in normalizing different forms of atherogenic dyslipidemia. Although statins are a class of drugs which primarily lower low-density lipoprotein cholesterol, fibrates decrease triglycerides, normalize the low-density lipoprotein cholesterol profile, and increase high-density lipoprotein cholesterol. As lipids are important determinants for cardiovascular diseases, these drugs reduce cardiovascular morbidity. However, a number of recent studies indicate that, in addition to their lipid-normalizing activities, statins and fibrates exhibit pleiotropic actions, such as inhibit inflammation, improve endothelial function, suppress the production of reactive oxygen species, etc. Statins are competitive inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, the rate-limiting enzyme of cholesterol synthesis, whereas fibrates are activators of the nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha). The similarity between the pleiotropic effects of statins and fibrates is remarkable and suggests a mechanistic link between these two classes of drugs. Here we discuss recent data on the cross-talk between statins and PPARalpha agonists and the mechanisms behind these actions.
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PMID:Cross-talk between statins and PPARalpha in cardiovascular diseases: clinical evidence and basic mechanisms. 1843 44

The nuclear receptor peroxisome proliferator-activated receptor alpha (PPARalpha) is recognized as the primary target of the fibrate class of hypolipidemic drugs and mediates lipid lowering in part by activating a transcriptional cascade that induces genes involved in the catabolism of lipids. We report here the characterization of three novel PPARalpha agonists with therapeutic potential for treating dyslipidemia. These structurally related compounds display potent and selective binding to human PPARalpha and support robust recruitment of coactivator peptides in vitro. These compounds markedly potentiate chimeric transcription systems in cell-based assays and strikingly lower serum triglycerides in vivo. The transcription networks induced by these selective PPARalpha agonists were assessed by transcriptional profiling of mouse liver after short- and long-term treatment. The induction of several known PPARalpha target genes involved with fatty acid metabolism were observed, reflecting the expected pharmacology associated with PPARalpha activation. We also noted the down-regulation of a number of genes related to immune cell function, the acute phase response, and glucose metabolism, suggesting that these compounds may have anti-inflammatory action in the mammalian liver. Whereas these compounds are efficacious in acute preclinical models, extended safety studies and further clinical testing will be required before the full therapeutic promise of a selective PPARalpha agonist is realized.
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PMID:Molecular characterization of novel and selective peroxisome proliferator-activated receptor alpha agonists with robust hypolipidemic activity in vivo. 1897 26

Fenofibrate, widely used for the treatment of dyslipidemia, activates the nuclear receptor, peroxisome proliferator-activated receptor alpha. However, liver toxicity, including liver cancer, occurs in rodents treated with fibrate drugs. Marked species differences occur in response to fibrate drugs, especially between rodents and humans, the latter of which are resistant to fibrate-induced cancer. Fenofibrate metabolism, which also shows species differences, has not been fully determined in humans and surrogate primates. In the present study, the metabolism of fenofibrate was investigated in cynomolgus monkeys by ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOFMS)-based metabolomics. Urine samples were collected before and after oral doses of fenofibrate. The samples were analyzed in both positive-ion and negative-ion modes by UPLC-QTOFMS, and after data deconvolution, the resulting data matrices were subjected to multivariate data analysis. Pattern recognition was performed on the retention time, mass/charge ratio, and other metabolite-related variables. Synthesized or purchased authentic compounds were used for metabolite identification and structure elucidation by liquid chromatographytandem mass spectrometry. Several metabolites were identified, including fenofibric acid, reduced fenofibric acid, fenofibric acid ester glucuronide, reduced fenofibric acid ester glucuronide, and compound X. Another two metabolites (compound B and compound AR), not previously reported in other species, were characterized in cynomolgus monkeys. More importantly, previously unknown metabolites, fenofibric acid taurine conjugate and reduced fenofibric acid taurine conjugate were identified, revealing a previously unrecognized conjugation pathway for fenofibrate.
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PMID:Fenofibrate metabolism in the cynomolgus monkey using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry-based metabolomics. 1925 19

Peroxisome proliferator-activated receptor alpha (PPARalpha) is a ligand-activated transcription factor that belongs to the steroid hormone receptor superfamily. PPARalpha is expressed predominantly in tissues that have a high level of fatty acid catabolism, such as liver, heart, and muscle. PPARalpha regulates the expression of a number of genes critical for lipid and lipoprotein metabolism. PPARalpha ligand fibrates have been used for the treatment of dyslipidemia due to their ability to lower plasma triglyceride levels and elevate HDL cholesterol levels. PPARalpha activators have been shown to regulate obesity in rodents by both increasing hepatic fatty acid oxidation and decreasing the levels of circulating triglycerides responsible for adipose cell hypertrophy and hyperplasia. However, these effects of PPARalpha on obesity and lipid metabolism may be exerted with sexual dimorphism and seem to be influenced by estrogen. Estrogen inhibits the actions of PPARalpha on obesity and lipid metabolism through its effects on PPARalpha-dependent regulation of target genes. Thus, the use of fibrates seems to be effective in men and postmenopausal women with obesity and lipid disorders, but not in premenopausal women with functioning ovaries.
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PMID:The role of PPARalpha in lipid metabolism and obesity: focusing on the effects of estrogen on PPARalpha actions. 1964 54

Fibrates, the ligands of peroxisome proliferator-activated receptor alpha (PPARalpha), are used as a class of lipid-lowering drugs in clinical practice for the treatment of dyslipidemia. Fibrates are well tolerated in most cases concomitantly with occasional adverse reactions including muscular toxicity, which is enhanced by the combination with statins. This study was designed to investigate the effects of bezafibrate as a PPARalpha agonist on human embryo rhabdomyosarcoma (RD) cells and possible mechanisms responsible for bezafibrate-mediated myopathy. The results revealed that bezafibrate caused a dose-dependent decrease in cell viability, which was fortified in association with atorvastatin at a pharmacological dose. Bezafibrate at toxic doses of 300 and 1000microM upregulated PPARalpha at the mRNA level, counteracted by a PPARalpha antagonist (MK886). Bezafibrate at a toxic dose induced typical apoptotic characteristics related to the inhibition of phosphorylation of Akt which was blocked by PPARalpha antagonist. Toxic doses of bezafibrate initiated a significant increase in pyruvate dehydrogenase kinase 4 mRNA and protein levels, compromised by MK886. These results suggest the critical roles of PPARalpha signaling in bezafibrate-induced myotoxicity and the involvement of apoptosis through Akt pathway.
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PMID:Bezafibrate induces myotoxicity in human rhabdomyosarcoma cells via peroxisome proliferator-activated receptor alpha signaling. 1968 50


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