PPARγ Modulators Research Articles

269 The PPAR-γ modulator, N-acetyl-GED, protects from epithelial-mesenchymal-transition to human hair follicles: Potential relevance for scarring alopecia

269 The PPAR-γ modulator, N-acetyl-GED, protects from epithelial-mesenchymal-transition to human hair follicles: Potential relevance for scarring alopecia

Elucidation of protective efficacy of Pentahydroxy flavone isolated from Madhuca indica against arsenite-induced cardiomyopathy: Role of Nrf-2, PPAR-γ, c-fos and c-jun

BackgroundMadhuca indica J. F. Gmel. (Sapotaceae) is widely used ethnobotanically as anti-diabetic, antipyretic, hepatoprotective, anti-inflammatory and analgesic. It was shown to possess potent anti-apoptotic property. The aim of the studyTo evaluate the possible mechanism of action of isolated phytoconstituent from Madhuca indica Leaves methanolic extract (MI-ALC) on arsenic-induced cardiotoxicity in rats. Materials and methodsThe 3,5,7,3′,4′-Pentahydroxy flavone (QTN) was isolated and characterized by using HPTLC, 1H NMR, and LC–MS from MI-ALC. QTN (5, 10 and 20mg/kg, p.o.) was administered in arsenic intoxicated rats (5mL/kg, p.o.) for 28days and evaluated for various behavioral, biochemical, molecular and ultra-histological changes. ResultsTreatment with QTN (10 and 20mg/kg, p.o.) significantly inhibited (p<0.05) arsenic-induced electrocardiographic, hemodynamic and left ventricular function alterations. Elevated levels of cardiac markers (LDH, CK-MB, AST, ALT, and ALP), altered lipid metabolism (total cholesterol, triglyceride, LDL, HDL, and VLDL) was significantly restored (p<0.05) by QTN. It also significantly inhibited (p<0.05) altered cardiac oxido-nitrosative stress, Na-K-ATPase level and mitochondrial enzymes (I–IV) activity after arsenite administration. QTN significantly increased (p<0.05) myocardial Nrf-2, PPAR-γ and significantly decreased (p<0.05) myocardial c-fos and c-jun mRNA expressions. Flow cytometric analysis showed that treatment with QTN (10 and 20mg/kg) significantly inhibited (p<0.05) arsenite-induce ROS and apoptosis. It also reduced ultra-histological aberrations induced by sodium arsenite. ConclusionAdministration of 3,5,7,3′,4′- Pentahydroxy flavone (i.e. Quercetin (QTN)) isolated from MI-ALC showed significant protection against arsenic-induced oxido-nitrosative stress and myocardial injury via modulation of Nrf2, PPAR-γ, and apoptosis.

The Ability of Exercise-Associated Oxidative Stress to Trigger Redox-Sensitive Signalling Responses.

In this review, we discuss exercise as an oxidative stressor, and elucidate the mechanisms and downstream consequences of exercise-induced oxidative stress. Reactive oxygen species (ROS) are generated in the mitochondria of contracting skeletal myocytes; also, their diffusion across the myocyte membrane allows their transport to neighbouring muscle tissue and to other regions of the body. Although very intense exercise can induce oxidative damage within myocytes, the magnitudes of moderate-intensity exercise-associated increases in ROS are quite modest (~two-fold increases in intracellular and extracellular ROS concentrations during exercise), and so the effects of such increases are likely to involve redox-sensitive signalling effects rather than oxidative damage. Therefore, the responses of muscle and non-muscle cells to exercise-associated redox-sensitive signalling effects will be reviewed; for example, transcription factors such as Peroxisome Proliferator Activated Receptor-gamma (PPARγ) and Liver X-Receptor-alpha (LXRα) comprise redox-activable signalling systems, and we and others have reported exercise-associated modulation of PPARγ and/or LXRα-regulated genes in skeletal myocyte and in non-muscle cell-types such as monocyte-macrophages. Finally, the consequences of such responses in the context of management of chronic inflammatory conditions, and also their implications for the design of exercise training programmes (particularly the use of dietary antioxidants alongside exercise), will be discussed.

INT131 increases dendritic arborization and protects against Aβ toxicity by inducing mitochondrial changes in hippocampal neurons

In previous studies, we have demonstrated the beneficial effects of classic PPARγ agonists on neuroprotection against Aβ oligomer neurotoxicity in a double transgenic mouse model of Alzheimer' disease (AD). INT-131, a novel, non-thiazolidinedione compound that belongs to a new family of drugs, selective PPARγ modulators (SPPARMs), has provided an emerging opportunity for the treatment of type 2 diabetes mellitus and metabolic syndrome. However, its role in the central nervous system has not been studied. The aim of this study was to evaluate the putative neuroprotective role of INT131 in hippocampal neurons. We found that INT131 increased dendritic branching, promoted neuronal survival against Aβ amyloid, increased expression of PGC1-1α and modulated neuronal mitochondrial dynamics. Our results suggest that INT131, a drug that has been shown to be safe and effective in metabolic disorders, may constitute a new therapeutic alternative for AD.

Wogonin attenuates inflammation by activating PPAR-γ in alcoholic liver disease

Alcoholic liver disease (ALD) is one of the predominant causes of liver-related morbidity and mortality worldwide. However, effective therapy for ALD is still lacking. Wogonin, a major flavonoid compound, is found in Scutellaria baicalensis Georgi. Accumulating studies have revealed that wogonin possesses anti-inflammatory and anti-tumour activities in various models. However, the hepatoprotective activity of wogonin in ALD is still obscure. In this study, we found that wogonin significantly attenuated inflammatory response in EtOH-fed mice, and reduced the expression of inflammatory cytokines such as TNF-α and IL-6 in EtOH-induced RAW264.7 cells. Furthermore, our findings showed that wogonin remarkably induced the expression of PPAR-γ in vivo and in vitro. Compared with the wogonin-treated group, blockade of PPAR-γ with inhibitor (T0070907) or PPAR-γ small interfering (si)-RNA were applied in RAW264.7 cells to evaluate the involvement of wogonin in alleviating EtOH-induced inflammation. Moreover, forced expression of PPAR-γ further suppressed the expression of TNF-α and IL-6 when treated with wogonin on EtOH-induced RAW264.7 cells. In addition, it was demonstrated that wogonin remarkably suppressed PPAR-γ-meditated phosphorylation and activation of NF-κB-P65. In conclusion, our results indicated that wogonin may serve as an effective modulator of PPAR-γ by down-regulating NF-κB pathway, thereby attenuated inflammatory response in ALD.

Selective Tissue Distribution Mediates Tissue-Dependent PPARγ Activation and Insulin Sensitization by INT131, a Selective PPARγ Modulator.

The mechanisms underlying the enhancement of insulin sensitivity by selective peroxisome proliferator-activated receptor γ modulators (sPPARγMs) are still not completely known. Here, the representative sPPARγM, INT131, was used as a probe to investigate the insulin-sensitizing mechanisms of sPPARγM in the context of tissue selective compound distribution and PPARγ regulation. First, 30 mg kg−1 INT131 was observed to produce an insulin-sensitizing effect comparable to that of 10 mg kg−1 rosiglitazone (RSG) in both db/db and DIO mice using the oral glucose and insulin tolerance tests. Similar to RSG, INT131 significantly increased brown adipose tissue (BAT) mass and adipocyte size and up-regulated the expression of BAT-specific genes. Compared with RSG, INT131 exhibited greater potency in inducing white adipose tissue (WAT) browning, decreasing adipocyte size, and increasing BAT-specific and function-related gene expression in subcutaneous WAT (sWAT). However, it did not induce hepatomegaly or hepatic steatosis, which is associated with lower levels of lipogenic genes expression. Pharmacokinetic analysis reveals that in contrast with RSG, INT131 shows higher Cmax, and much longer residency time (AUC0−12h), as well relatively lower elimination rate in adipose tissues and skeletal muscle, this demonstrated INT131 distributed predominantly in adipose tissue. Whereas, INT131 was less abundant in the liver. These results thus suggest that the tissue-selective distribution underlies INT131's selective PPARγ modulation. Compounds favoring adipose tissue may aid in development of better, safer sPPARγM to address the insulin resistance of diabetes.

Synthesis, molecular docking and anti-diabetic evaluation of 2,4-thiazolidinedione based amide derivatives

A series of thiazolidinedione based amide derivatives were designed, synthesized and docked against the PPARγ receptor target. 11 compounds from the series with good glide scores were selected for in vivo antidiabetic study based on streptozotocin induced diabetic rat model. It was observed that 4 compounds (6c, 6e, 6m &6n) showed significantly good antidiabetic activity in comparison to rosiglitazone and pioglitazone as reference drugs. Compound 6c appeared as the most potent derivative in lowering blood glucose level and showed excellent interaction with SER 342, ILE 281, pi-pi interaction with ARG 288 and halogen bond interaction with LYS 367. Further, PPARγ transactivation and gene expression studies of compound 6c were carried out to investigate the possible mechanism of action through PPARγ modulation. Compound 6c exhibited 53.65% transactivation and elevated PPARγ gene expression by 2.1 folds. The biochemical parameters (AST, ALT and ALP levels) were found within the range with no noteworthy damage to liver.

S1P/PPARγ axis metabolically reprograms the T cells to modulate their anti-tumor potential

Abstract Adoptive T cell transfer (ACT) holds promise in cancer therapy, and strategies to further improve its efficacy are being tested. It is reported that sphingosine 1-phosphate (S1P), generated by sphingosine kinase 1 (SphK1), regulates lymphocyte egress into circulation and also plays role in the differentiation of regulatory T cells and T helper-17 cells. Here, we examined the roles of SphK1/S1P signalling in regulating antitumor potential of T cells. We found that adoptive transfer of melanoma epitope gp100 reactive CD8 T cells (pMel) with SphK1 deficiency showed improved tumor control in murine melanoma model. Our data also indicated that Sphk1−/− T cells exhibited enhanced central memory phenotype, higher mitochondrial respiration and resistance to TGF-β mediated suppression. Importantly, Sphk1−/− T cells spontaneously secreted higher levels of IL17 compared to their wild type counterparts. Mechanistically, we demonstrate that SphK1/S1P signaling regulates IL17 generation through attenuation of PPARγ, which is down-regulated in Sphk1−/− T cells. In reciprocal studies, addition of S1P in culture media enhanced PPARγ expression, resulting in decreased IL17 production in Sphk1−/− T cells. Furthermore, down-regulation of PPARγ in Sphk1−/− T cell increased lipolysis to produce free fatty acids and metabolically reprogram T cells to depend on mitochondrial metabolism for meeting their energy demand. Thus, our data reveal that SphK1/S1P signaling regulates anti-tumor functions and persistence of T cells by controlling T cell energy metabolism through induction of lipolysis via PPARγ modulation. Overall, these data highlight the clinical potential of targeting SphK/S1P axis for improving efficacy of ACT for solid tumors.

Pharmacological PPARγ modulation regulates sebogenesis and inflammation in SZ95 human sebocytes

The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) controls the expression of genes involved in the regulation of lipid and glucose metabolism, cell proliferation/differentiation as well as inflammatory pathways. Pivotal studies in human sebocytes and isolated sebaceous glands have raised the interesting possibility that compounds acting on PPARγ can modulate sebaceous lipids and inflammation and, as such, may be useful in the treatment of acne. To investigate the role of this receptor in the regulation of lipid synthesis, proliferation and inflammation, we used the SZ95 sebaceous gland cell line stimulated with insulin. In sebocytes, insulin signaling activated the phosphatidylinositide 3-kinase-Akt (PI3K/Akt) and mammalian target of rapamycin (mTOR) pathways, which, in turn, induced high protein/lipid synthesis, increased cell growth and proliferation as well as inflammation. As regards lipogenesis, insulin initially stimulated the formation of unsaturated lipids and then the neosynthesis of lipids. The results showed, that the modulation of PPARγ, counteracted the insulin-induced altered lipogenesis, evident through a decrease in gene expression of key enzymes responsible for the synthesis of fatty acids, and through a reduction of lipid species synthesis analyzed by Oil/Nile Red staining and GC–MS. PPARγ modulation also regulated the insulin-induced proliferation, inhibiting the cell cycle progression and p21WAF1/CIP1 (p21) protein reduction. Moreover, the expression of inflammatory cytokines, induced by insulin or lipopolysaccharide (LPS), was down-modulated. In PPARγ-deficient cells or in the presence of GW9662 antagonist, all these observed effects were abolished, indicating that PPARγ activation plays a role in regulating alteration of lipogenesis, cell proliferation and inflammatory signaling. We demonstrated that selective modulation of PPARγ activity is likely to represent a therapeutic strategy for the treatment of acne.

Apigenin, a modulator of PPARγ, attenuates HFD-induced NAFLD by regulating hepatocyte lipid metabolism and oxidative stress via Nrf2 activation

Lipid metabolic disorders and oxidative stress in the liver are key steps in the progression of nonalcoholic fatty liver disease (NAFLD), which is a major risk factor for the development of metabolic syndrome. To date, no pharmacological treatment for this condition has been approved. Our previous study has found that the food-derived compound apigenin (Api) significantly attenuates obesity-induced metabolic syndrome by acting as a peroxisome proliferator-activated receptor gamma modulator (PPARM). Herein, a high fat diet (HFD) induced NAFLD model was used to dig out whether Api had the effect on NAFLD. The results showed that Api had obvious effect in restraining NAFLD progression, including attenuating HFD induced lipid accumulation and oxidative stress in vivo. As a PPARM, although Api did significantly inhibit the expression of PPARγ target genes encoding the protein associated with lipid metabolism, it had no obvious activating effect on PPARγ. Interestingly, we found that Api promoted Nrf2 into the nucleus, thereby markedly activating Nrf2 to inhibit the lipid metabolism related genes and increase the oxidative stress related genes. Further Nrf2 knockdown/knockout and overexpression experiments showed that Api regulating PPARγ target genes was dependent on Nrf2 activation and the activation of Nrf2 counteracted the activation effect of PPARγ by Api. Importantly, we also found that Api might bind with Nrf2 via auto dock and ITC assay. Therefore, our results indicate that Api ameliorates NAFLD by a novel regulating mode of Nrf2 and PPARγ in inhibiting lipid metabolism and oxidative stress abnormity.

Role of glycogen synthase kinase-3β and PPAR-γ on epithelial-to-mesenchymal transition in DSS-induced colorectal fibrosis.

BackgroundIntestinal fibrosis is characterized by abnormal production and deposition of extracellular matrix (ECM) proteins by activated myofibroblasts. The main progenitor cells of activated myofibroblasts are the fibroblasts and the epithelial cells, the latter through the epithelial-mesenchymal transition (EMT).AimTo evaluate the action of the new PPAR-γ modulator, GED-0507-34 Levo (GED) on the expression of EMT associated and regulatory proteins such as TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, and GSK-3β, in a mouse model of DSS-induced intestinal fibrosis.MethodsChronic colitis and fibrosis were induced by oral administration of 2.5% DSS (w/v) for 6 weeks. GW9662 (GW), a selective PPAR-γ inhibitor, was also administered by intraperitoneal injection at the dose of 1 mg/kg/day combined with GED treatment. All drugs were administered at the beginning of the second cycle of DSS (day 12). 65 mice were randomly divided into five groups (H2O as controls n = 10, H2O+GED n = 10, DSS n = 15, DSS+GED n = 15, DSS+GED+GW n = 15). The colon was excised for macroscopic examination and histological and morphometric analyses. The level of expression of molecules involved in EMT and fibrosis, like TGF-β, Smad3, E-cadherin, Snail, ZEB1, β-catenin, GSK-3β and PPAR-γ, was assessed by immunohistochemistry, immunofluorescence, western blot and Real Time PCR.ResultsGED improved the DSS-induced chronic colitis and fibrosis. GED was able to reduce the expression of the main fibrosis markers (α-SMA, collagen I-III and fibronectin) as well as the pivotal pro-fibrotic molecules IL-13, TGF-β and Smad3, while it increased the anti-fibrotic PPAR-γ. All these GED effects were nullified by co-administration of GW with GED. Furthermore, GED was able to normalize the expression levels of E-cadherin and β-catenin and upregulated GSK-3β, that are all known to be involved both in EMT and fibrosis.ConclusionsThe DSS-induced intestinal fibrosis was improved by the new PPAR-γ modulator GED-0507-34 Levo through the modulation of EMT mediators and pro-fibrotic molecules and through GSK-3β induction.

Interleukin-18-induced cell adhesion molecule expression is associated with feedback regulation by PPAR-γ and NF-κB in Apo E-/- mice.

Focal recruitment of monocytes and lymphocytes is one of the earliest detectable cellular responses in atherosclerotic lesion formation. Endothelium may regulate leukocyte recruitment by expressing specific adhesion molecules. Interleukin-18 is a proinflammatory cytokine that plays an important role in vascular pathologies. The present study highlights the modulation of adhesion molecules and PPAR-γ by IL-18 and proposes a novel feedback mechanism by which PPAR-γ may regulate IL-18 expression. Three groups of normal chow diet-fed, male Apo E-/- mice, aged 12weeks (n = 6/group) were employed: Gp I, phosphate-buffered saline (PBS) (2 mo): Gp II, recombinant IL-18 (rIL-18) (1 mo) followed by PBS (1 mo); Gp III, rIL-18 (1 mo) followed by pyrrolidine dithiocarbamate (PDTC) (1 mo). Significantly augmented mRNA expression of ICAM-1 (~5.7-fold), VCAM-1 (~3.6-fold), and NF-κB (~7-fold) was observed in Gp II mice as compared to Gp I, whereas PPAR-γ expression was not altered. PDTC treatment caused a significant downregulation of ICAM-1 (~4.2-fold), VCAM-1(~2-fold), and NF-κB (~4.5-fold) and upregulation of PPAR-γ expression (~5-fold) in Gp III mice. A similar trend was observed in protein expression. In vivo imaging results demonstrated a marked increase in probe (CF750 dye conjugated to VCAM-1 antibody) fluorescence intensity for VCAM-1 expression in Gp II mice, whereas it was moderately decreased in Gp III. PPAR-γ was found to significantly downregulate both IL-18 levels and IL-18-induced adhesion molecules. The underlying mechanism was found to be via inhibition of NF-κB activity by PDTC, thereby leading to decreased adherence of monocytes to the activated endothelial cells and a step to halt the progression and development of atherosclerotic lesions.

Metformin and low dose radiation modulates cisplatin-induced oxidative injury in rat via PPAR-γ and MAPK pathways

Cisplatin (CIS) is a chemotherapeutic agent used for therapy of many tumors and has been limited by its toxicity. The aim of this study was to investigate the role of Peroxisome proliferator–activated receptor-gamma (PPAR-γ), mitogen-activated protein kinase (MAPK) and nuclear factor-kappa B(NFkB) in the pathogenesis of hepatic damage induced by CIS, and investigated the modulatory effect of metformin (MET) and/or low dose gamma radiation (LDR) on CIS-induced hepatotoxicity in rats. CIS(7.5 mg/kg, i.p.) hepatotoxicity was evidenced by alteration of serum hepatic indices (ALT and AST) accompanied with decreased hepatic PPAR-γ, superoxide dismutase (SOD) activities and reduced glutathione (GSH) content, whereas the levels of malondialdehyde (MDA), total nitrate/nitrite (NOx) and NFkB significantly increased as well as MAPK activity compared with the control, MET and LDR groups. Furthermore, CIS induces apoptosis as indicated by an elevation of hepatic caspase-3. Treatment with MET (150 mg/kg, orally for 14 days) and/or LDR (0.5 Gy), prior to CIS alleviates CIS-induced hepatic damage by mitigating oxidative/ nitrosative stress and PPAR-γ activity reduction, hepatic caspase-3 elevation, and inhibition of NFκB, and MAPK activity levels. Conclusions: Modulation of PPAR-γ, MAPK and NFkB might contribute to amelioration of CIS-induced hepatic toxicity.

Cinnamaldehyde potentially attenuates gestational hyperglycemia in rats through modulation of PPARγ, proinflammatory cytokines and oxidative stress

Cinnamon has a history of use for medicinal purposes and its major benefits have been linked to cinnamaldehyde. The present study aimed to investigate the hypoglycemic action of cinnamaldehyde against fatty-sucrosed diet/streptozotocin (FSD/STZ)-rat model of gestational diabetes. Female albino rats were divided into three groups. Group I fed with normal diet (ND) while group II and III were fed with FSD for eight weeks (five weeks pre-gestational and three weeks gestational). Rats of group III were administered with a daily oral dose of 20mg/kg cinnamaldehyde one week before mating onward. At the 7th day of gestation, FSD-fed rats were injected intraperitoneally with STZ (25mg/kg b.wt.) to induce gestational diabetes. Pre-mating treatment of cinnamaldehyde controls hyperphagia and glucose intolerance during the gestational period than in diabetic rats. It also reduced levels of fructosamine, total cholesterols, triglycerides, leptin, tumor necrosis factor-alpha (TNF-α), malondialdehyde (MDA) and nitric oxide (NO), while it significantly increased levels of high-density lipoprotein (HDL)-cholesterol, adiponectin, liver glycogen, reduced glutathione (GSH) and catalase activity at term pregnancy. In addition, cinnamaldehyde administration up-regulated the mRNA expression of peroxisome proliferated activated receptor-gamma (PPARγ) and also ameliorated the number of viable fetuses, implantation loss sites, fetal glucose and insulin levels. In conclusion, cinnamaldehyde has safe hypoglycemic action on gestational diabetes by potentiating insulin secretion and sensitivity through activating the antioxidant defense system, suppressing pro-inflammatory cytokines production, upregulating PPARγ gene expression and alleviating the reproductive performance.

Thiazolidinediones and PPAR orchestra as antidiabetic agents: From past to present

Thiazolidinediones a class of drug, that provided a major breakthrough in the management of type 2 diabetes since 1990. Following the discovery of PPARs, TZDs were the first class to be reported as PPARγ modulators. This review is an attempt to summarize the chemical modifications around TZDs in past two decades to obtain a potent antidiabetic molecule. TZDs literature were initially dominated by their hypoglycemic & hypolipidemic activities, later PPARγ activity was also been incorporated. Moreover, in some cases, both benzyl and benzylidene derivatives were reported in the same manuscript for the sake of comparison. We thought of presenting the review on the basis of the variation in the linker region. Optimal linker at the time of discovery of the Ciglitazone was oxymethyl and it went on to evolve as oxyethyl (Pioglitazone) and oxyethylamino (Rosiglitazone). Few attempts were made to restrict the flexibility of the linker by introducing the cyclic structures and were summarized immediately after the respective linker class.

Differences in the modulation of reactive species, lipid bodies, cyclooxygenase-2, 5-lipoxygenase and PPAR-γ in cerebral malaria-susceptible and resistant mice

Proinflammatory responses are associated with the severity of cerebral malaria. NO, H2O2, eicosanoid and PPAR-γ are involved in proinflammatory responses, but regulation of these factors is unclear in malaria. This work aimed to compare the expression of eicosanoid-forming-enzymes in cerebral malaria-susceptible CBA and C57BL/6 and −resistant BALB/c mice. Mice were infected with Plasmodium berghei ANKA, and the survival rates and parasitemia curves were assessed. On the sixth day post-infection, cyclooxygenase-2 and 5-lipoxygenase in brain sections were assessed by immunohistochemistry, and, NO, H2O2, lipid bodies, and PPAR-γ expression were assessed in peritoneal macrophages. The C57BL/6 had more severe disease with a lower survival time, higher parasitemia and lower production of plasmodicidal NO and H2O2 molecules than BALB/c. Enhanced COX-2 and 5-LOX expression were observed in brain tissue cells and vessels from C57BL/6 mice, and these mice expressed higher constitutive PPAR-γ levels. There was no translocation of PPAR-γ from cytoplasm to nucleus in macrophages from these mice. CBA mice had enhanced COX-2 expression in brain tissue cells and vessels and also lacked PPAR-γ cytoplasm-to-nucleus translocation. The resistant BALB/c mice presented higher survival time, lower parasitemia and higher NO and H2O2 production on the sixth day post-infection. These mice did not express either COX-2 or 5-LOX in brain tissue cells and vessels. Our data showed that besides the high parasite burden and lack of microbicidal molecules, an imbalance with high COX-2 and 5-LOX eicosanoid expression and a lack of regulatory PPAR-γ cytoplasm-to-nucleus translocation in macrophages were observed in mice that develop cerebral malaria.

Structural exploration of PPARγ modulators through pharmacophore mapping, fragment-based design, docking, and molecular dynamics simulation analyses

Peroxisome proliferator-activated gamma receptor is an attractive therapeutic target involving various types of metabolic syndrome. Viewing the importance of peroxisome proliferator-activated gamma receptor modulators, ligand and energetically optimized pharmacophores (e-pharmacophore), hologram-based quantitative structural activity relationships, and classification-based Bayesian models were developed, followed by molecular docking, mechanics, and dynamic analyses to search for essential structural requirements in the molecules for potent and selective peroxisome proliferator-activated gamma receptor modulation. Both ligand and e-pharmacophore models suggest that aromatic ring feature plays the crucial role, whereas the hologram-based quantitative structural activity relationships study indicates that phenyl and indole aromatic rings are essential scafolds for imparting selective peroxisome proliferator-activated gamma receptor modulation. Further, the e-pharmacophore model, molecular docking, and dynamics studies depict the importance of a carboxyl group for modulating peroxisome proliferator-activated gamma receptor agonistic activity through generating strong H-bonds with the active amino acid residues (His323, Tyr327, His449, and Tyr473, etc). The multi chemometrics modeling studies provide some insight into the prime structural features responsible for significant agonistic property of peroxisome proliferator-activated gamma receptor ligands.

PPARγ Modulation of Cytokine-Stimulated MUC16 (CA125) Expression in Breast and Ovarian Cancer-Derived Cells.

CA125 is serum tumor marker consisting of an epitope carried by a portion of the extremely large (>3 MDa), heavily glycosylated cell surface transmembrane mucin, MUC16. In malignancies, membrane bound mucins lose their polarized distribution, become aberrantly over-expressed and protect tumor cells from the actions of chemotherapeutic agents as well as the immune system. Previously, we described stimulation of MUC16 expression by the proinflammatory cytokines, tumor necrosis factor α (TNFα) and interferon γ (IFNγ), in breast and ovarian cancer cells and tissues. Herein, we show that PPARγ modulates cytokine-stimulated MUC16 in a complex manner: at low concentrations (<10 µM) rosiglitazone further potentiates cytokine-driven MUC16 expression while at high concentrations (>20 µM) rosiglitazone antagonizes cytokine stimulation. Rosiglitazone actions were fully reversible by the PPARγ antagonist, GW9662. Furthermore, siRNA-mediated PPARγ knockdown also prevented a large portion of high dose rosiglitazone suppression of MUC16 expression indicating that rosiglitazone inhibition is largely PPARγ-dependent. Cytokines greatly (>75%) suppressed PPARγ expression. Conversely, PPARγ activation by rosiglitazone at either low or high concentrations greatly (>75%) suppressed NFκB/p65 expression. NFκB/p65 expression was largely preserved in the presence of cytokines at low, but not high, rosiglitazone concentrations accounting for the different concentration dependent effects on MUC16 expression. Collectively, these studies demonstrate that PPARγ is an important modulator of MUC16 expression. The ability to deliver high doses of PPARγ agonists to MUC16-expressing tumors offers an avenue to reduce expression of this protective glycoprotein and increase tumor sensitivity to killing by chemotherapeutic drugs and the immune system. J. Cell. Biochem. 118: 163-171, 2017. © 2016 Wiley Periodicals, Inc.

Activation of PPARγ by a Natural Flavonoid Modulator, Apigenin Ameliorates Obesity-Related Inflammation Via Regulation of Macrophage Polarization

PPARγ has emerged as a master regulator of macrophage polarization and is the molecular target of the thiazolidinedione drugs. Here we show that apigenin binds and activates PPARγ by acting as a modulator. Activation of PPARγ by apigenin blocks p65 translocation into nuclei through inhibition of p65/PPARγ complex translocation into nuclei, thereby decreasing NF-κB activation and favoringM2 macrophage polarization. In HFD and ob/ob mice, apigenin significantly reverses M1 macrophage into M2 and reduces the infiltration of inflammatory cells in liver and adipose tissues, as well as decreases the levels of pro-inflammatory cytokines, thereby alleviating inflammation. Strikingly, apigenin reduces liver and muscular steatosis, decreases the levels of ALT, AST, TC and TG, improving glucose resistance obviously. Unlike rosiglitazone, apigenin does not cause significant weight gain, osteoporosis et al. Our findings identify apigenin as a modulator of PPARγ and a potential lead compound for treatment of metabolic disorders.

Peroxisome Proliferator-Activated Receptor γ Activity is Required for Appropriate Cardiomyocyte Differentiation.

Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the PPAR nuclear receptor superfamily. Although PPARγ acts as a master transcription factor in adipocyte differentiation, it is also associated with a variety of cell functions including carbohydrate and lipid metabolism, glucose homeostasis, cell proliferation and cell differentiation. This study aimed to assess the expression level of PPARγ in order to address its role in cardiac cell differentiation of mouse embryonic stem cells (mESCs). In this an intervening study, mESCs were subjected to cardiac differentiation. Total RNA was extracted from the cells and quantitative real time polymerase chain reaction (qPCR) was carried out to estimate level of gene expression. Furthermore, the requirement of PPARγ in cardiac differentiation of mESCs, during cardiac progenitor cells (CPCs) formation, was examined by applying the respective agonist and antagonist. The obtained data revealed an elevation in the expression level of PPARγ during spontaneous formation of CPCs and cardiomyocytes. Our results indicated that during CPC formation, PPARγ inactivation via treatment with GW9662 (GW) reduced expression of CPC and cardiac markers. We conclude that PPARγ modulation has an effective role on cardiac differentiation of mESCs at the early stage of cardiomyogenesis.