Adipogenic Effects of Cresyl Diphenyl Phosphate (Triphenyl Phosphate Alternative) through Peroxisome Proliferator-Activated Receptor Gamma Pathway: A Comprehensive Study Integrating In Vitro, In Vivo, and In Silico from Molecule to Health Risk.

Cresyl diphenyl phosphate (CDP), a novel organophosphate ester (OPE), has been detected in various environmental and human samples. However, there is very limited knowledge regarding its toxicity, mechanisms of action, and potential health risks. Using new alternative methods (NAMs), across the molecular interactions, signaling pathways, cell functions, animal effects, and population risks, we investigated the potential adipogenic effects and associated risks of CDP and legacy OPE triphenyl phosphate (TPHP) by acting on peroxisome proliferator-activated receptor gamma (PPARγ). Among the 19 screened OPEs, CDP bound to PPARγ with the highest binding potency, followed by TPHP. CDP activated PPARγ through fitting into the binding pocket with strong hydrophobicity and hydrogen bond interactions; CDP exhibited higher potency compared to TPHP. In 3T3-L1 cells, CDP enhanced the PPARγ-mediated adipogenesis activity, exhibiting greater potency than TPHP. The intracellular concentration and receptor-bound concentrations (RBC) of CDP were also higher than those of TPHP in both HEK293 cells and 3T3-L1 cells. In mice, exposure to CDP activated the PPARγ-mediated adipogenic pathway, leading to an increased white adipose tissue weight gain. Overall, CDP could bind to and activate PPARγ, thereby promoting preadipocyte differentiation and the development of white adipose tissue. Its potential obesogenic risks should be of high concern.

Lipid Storage, Lipolysis, and Lipotoxicity in Obesity.

The ratio of free fatty acid (FFA) turnover decreases significantly with the expansion of white adipose tissue. Adipose tissue and dietary saturated fatty acid levels significantly correlate with an increase in fat cell size and number. The G0/G1 switch gene 2 increases lipid content in adipocytes and promotes adipocyte hypertrophy through the restriction of triglyceride (triacylglycerol: TAG) turnover. Hypoxia in obese adipose tissue due to hypertrophic adipocytes results in excess deposition of extracellular matrix (ECM) components. Cluster of differentiation (CD) 44, as the main receptor of the extracellular matrix component regulates cell-cell and cell-matrix interactions including diet-induced insulin resistance. Excess TAGs, sterols, and sterol esters are surrounded by the phospholipid monolayer surface and form lipid droplets (LDs). Once LDs are formed, they grow up because of the excessive amount of intracellular FFA stored and reach a final size. The ratio of FFA turnover/lipolysis decreases significantly with increases in the degree of obesity. Dysfunctional adipose tissue is unable to expand further to store excess dietary lipids, increased fluxes of plasma FFAs lead to ectopic fatty acid deposition and lipotoxicity. Reduced neo-adipogenesis and dysfunctional lipid-overloaded adipocytes are hallmarks of hypertrophic obesity linked to insulin resistance. Obesity-associated adipocyte death exhibits feature of necrosis-like programmed cell death. Adipocyte death is a prerequisite for the transition from hypertrophic to hyperplastic obesity. Increased adipocyte number in obesity has life-long effects on white adipose tissue mass. The positive correlation between the adipose tissue volume and magnetic resonance imaging proton density fat fraction estimation is used for characterization of the obesity phenotype, as well as the risk stratification and selection of appropriate treatment strategies. In obese patients with type 2 diabetes, visceral adipocytes exposed to chronic/intermittent hyperglycemia develop a new microRNAs' (miRNAs') expression pattern. Visceral preadipocytes memorize the effect of hyperglycemia via changes in miRNAs' expression profile and contribute to the progression of diabetic phenotype. Nonsteroidal anti-inflammatory drugs, metformin, and statins can be beneficial in treating the local or systemic consequences of white adipose tissue inflammation. Rapamycin inhibits leptin-induced LD formation. Collectively, in this chapter, the concept of adipose tissue remodeling in response to adipocyte death or adipogenesis, and the complexity of LD interactions with the other cellular organelles are reviewed. Furthermore, clinical perspective of fat cell turnover in obesity is also debated.

Persistent metabolic toxicities following developmental exposure to hexafluoropropylene oxide trimer acid (HFPO-TA): Roles of peroxisome proliferator activated receptor gamma.

BACKGROUND: Hexafluoropropylene oxide trimer acid (HFPO-TA), a perfluorooctanoic acid (PFOA) substitute, exhibited strong affinity and capability to activate peroxisome proliferator activated receptor gamma (PPARγ), a lipid metabolism regulator, suggesting potential to induce metabolic toxicities. METHODS: Fertile chicken eggs were exposed to 0, 0.5, 1 or 2 mg/kg (egg weight) HFPO-TA and incubated until hatch. Serum from 0- and 3- month-old chickens were subjected to liquid chromatography ultra-high resolution mass spectrometry for HFPO-TA concentration, while liver, pancreas and adipose tissue samples were collected for histopathological assessments. In ovo PPARγ reporter and silencing system were established with lentivirus microinjection. qRT-PCR and immunohistochemistry were utilized to evaluate the expression levels of PPARγ downstream genes. RESULTS: In 3-month-old animals developmentally exposed to HFPO-TA, adipose tissue hyperplasia, hepatic steatosis, pancreas islet hypertrophy and elevated serum free fatty acid / insulin levels were observed. Results of reporter assay and qRT-PCR indicated HFPO-TA-mediated PPARγ transactivation in chicken embryo. Silencing of PPARγ alleviated HFPO-TA-induced changes, while PPARγ agonist rosiglitazone mimicked HFPO-TA-induced effects. qRT-PCR and immunohistochemistry revealed that FASN and GPD1 were upregulated following developmental exposure to HFPO-TA in 3-month-old animals. CONCLUSIONS: Developmental exposure to HFPO-TA induced persistent metabolic toxicities in chickens, in which PPARγ played a central role.

Role of bioavailability and protein binding of four anionic perfluoroalkyl substances in cell-based bioassays for quantitative in vitro to in vivo extrapolations.

Perfluoroalkyl substances (PFAS) are persistent and pose a risk to human health. High throughput screening (HTS) cell-based bioassays may inform risk assessment of PFAS provided that quantitative in vitro to in vivo extrapolation (QIVIVE) can be developed. The QIVIVE ratio is the ratio of nominal (Cnom) or freely dissolved concentration (Cfree) in human blood to Cnom or Cfree in the bioassays. Considering that the concentrations of PFAS in human plasma and in vitro bioassays may vary by orders of magnitude, we tested the hypothesis that anionic PFAS bind to proteins concentration-dependently and therefore the binding differs substantially between human plasma and bioassays, which has an impact on QIVIVE. Solid phase microextraction (SPME) with C18-coated fibers served to quantify the Cfree of four anionic PFAS (perfluorobutanoate (PFBA), perfluorooctanoate (PFOA), perfluorohexane sulfonate (PFHxS) and perfluorooctane sulfonate (PFOS)) in the presence of proteins and lipid, medium components, cells and human plasma over five orders of magnitude in concentrations. The C18-SPME method was used to quantify the non-linear binding to proteins, human plasma and medium, and the partition constants to cells. These binding parameters were used to predict Cfree of PFAS in cell bioassays and human plasma by a concentration-dependent mass balance model (MBM). The approach was illustrated with a reporter gene assay indicating activation of the peroxisome proliferator-activated receptor gamma (PPARγ-GeneBLAzer). Blood plasma levels were collected from literature for occupational exposure and the general population. The QIVIVEnom ratios were higher than the QIVIVEfree ratios due to the strong affinity to proteins and large differences in protein contents between human blood and bioassays. For human health risk assessment, the QIVIVEfree ratios of many in vitro assays need to be combined to cover all health relevant endpoints. If Cfree cannot be measured, they can be estimated with the MBM and concentration-dependent distribution ratios.

Futile cycle of ß-oxidation and de novo lipogenesis are associated with essential fatty acids depletion in lipoatrophy.

Total absence of adipose tissue (lipoatrophy) is associated with the development of severe metabolic disorders including hepatomegaly and fatty liver. Here, we sought to investigate the impact of severe lipoatrophy induced by deletion of peroxisome proliferator-activated receptor gamma (PPARγ) exclusively in adipocytes on lipid metabolism in mice. Untargeted lipidomics of plasma, gastrocnemius and liver uncovered a systemic depletion of the essential linoleic (LA) and α-linolenic (ALA) fatty acids from several lipid classes (storage lipids, glycerophospholipids, free fatty acids) in lipoatrophic mice. Our data revealed that such essential fatty acid depletion was linked to increased: 1) capacity for liver mitochondrial fatty acid ß-oxidation (FAO), 2) citrate synthase activity and coenzyme Q content in the liver, 3) whole-body oxygen consumption and reduced respiratory exchange rate in the dark period, and 4) de novo lipogenesis and carbon flux in the TCA cycle. The key role of de novo lipogenesis in hepatic steatosis was evidenced by an accumulation of stearic, oleic, sapienic and mead acids in liver. Our results thus indicate that the simultaneous activation of the antagonic processes FAO and de novo lipogenesis in liver may create a futile metabolic cycle leading to a preferential depletion of LA and ALA. Noteworthy, this previously unrecognized cycle may also explain the increased energy expenditure displayed by lipoatrophic mice, adding a new piece to the metabolic regulation puzzle in lipoatrophies.

Physiological Convergence and Antagonism Between GR and PPARγ in Inflammation and Metabolism.

Nuclear receptors (NRs) are transcription factors that modulate gene expression in a ligand-dependent manner. The ubiquitously expressed glucocorticoid receptor (GR) and peroxisome proliferator-activated receptor gamma (PPARγ) represent steroid (type I) and non-steroid (type II) classes of NRs, respectively. The diverse transcriptional and physiological outcomes of their activation are highly tissue-specific. For example, in subsets of immune cells, such as macrophages, the signaling of GR and PPARγ converges to elicit an anti-inflammatory phenotype; in contrast, in the adipose tissue, their signaling can lead to reciprocal metabolic outcomes. This review explores the cooperative and divergent outcomes of GR and PPARγ functions in different cell types and tissues, including immune cells, adipose tissue and the liver. Understanding the coordinated control of these NR pathways should advance studies in the field and potentially pave the way for developing new therapeutic approaches to exploit the GR:PPARγ crosstalk.

Histone methyltransferase KMT2D mediated lipid metabolism via peroxisome proliferator-activated receptor gamma in prostate cancer.

Background: Prostate cancer (PCa) is the most common type of cancer in men. Destruction of or blocking lipid metabolism impairs the growth, proliferation, and survival of tumor cells. Recent studies on hepatic steatosis suggest that kinase tethers histone-lysine N-methyltransferase 2D (KMT2D) to peroxisome proliferator-activated receptor gamma (PPARγ), transactivating its target genes. Here, to determine a therapeutic approach that may interfere with PCa lipid metabolism, the interaction mechanism of KMT2D and PPARγ was verified in PCa. Methods: Molecular techniques and bioinformatics analysis were used to explore the relationship between KMT2D and lipid metabolism pathways in PCa. Moreover, the changes of lipid droplets were detected by oil red O staining and BODIPY staining. Molecular techniques were used to investigate the effect of KMT2D on PPARγ signaling in PCa cells. Co-immunoprecipitation (Co-IP) and DNA pull-down verified the mechanism of interaction between KMT2D and PPARγ. Results: KMT2D knockdown reduced the lipid droplet content in PC-3 and DU-145 cells and downregulated the expression of lipid metabolic genes. Low-dose rosiglitazone (ROSI) effectively activated the PPARγ pathway to promote lipid droplet synthesis and cell proliferation and migration. However, ROSI could not function effectively after KMT2D knockdown. Both co-IP and DNA pull-down analyses showed that KMT2D and PPARγ could be tethered to regulate the expression of PPARγ target genes. Conclusions: In PCa, KMT2D interacted with PPARγ, which directly participated in the regulation of lipid metabolism-related genes and affected lipid synthesis. Therefore, inhibiting the interaction between KMT2D and PPARγ is a potential therapeutic strategy.

Addressing Peroxisome Proliferator-Activated Receptor-gamma in 3-Nitropropionic Acid-Induced Striatal Neurotoxicity in Rats.

Telmisartan (TEL) is an angiotensin II type 1 receptor blocker and a partial activator of peroxisome proliferator-activated receptor-gamma (PPARγ), which regulates inflammatory and apoptotic pathways. Increasing evidence has demonstrated the PPARγ agonistic property of TEL in several brain disorders. This study aims to explore the neuroprotective impact of TEL in 3-nitropropionic acid (3-NP)-induced neurotoxicity in rats. The PPARγ effect of TEL was affirmed by using the PPARγ agonist pioglitazone (PIO), and the antagonist GW9662. 3-NP led to a significant reduction in body weight alongside motor and cognitive functioning. The striata of the 3-NP-treated rats showed energy-deficit, microglia-mediated inflammatory reactions, apoptotic damage as well as histopathological lesions. PIO and TEL improved motor and cognitive perturbations induced by 3-NP, as confirmed by striatal histopathological examination, energy restoration, and neuronal preservation. Both drugs improved mitochondrial biogenesis evidenced by elevated mRNA expression of PPARγ, PGC-1α, and TFAM, alongside increased striatal ATP and SDH. The mitochondrial effect of TEL was beyond PPARγ activation. As well, their anti-inflammatory effect was attributed to suppression of microglial activation, and protein expression of pS536 p65 NF-κB with marked attenuation of striatal inflammatory mediator's release. Anti-inflammatory cytokine IL-10 expression was concurrently increased. TEL effectively participated in neuronal survival as it promoted phosphorylation of Akt/GSK-3ß, further increased Bcl-2 expression, and inhibited cleavage of caspase-3. Interestingly, co-treatment with GW9662 partially revoked the beneficial effects of TEL. These findings recommend that TEL improves motor and cognitive performance, while reducing neuronal inflammation and apoptosis in 3-NP-induced neurotoxicity via a PPARγ-dependent mechanism.

Exploring the Nerve Regenerative Capacity of Compounds with Differing Affinity for PPARγ In Vitro and In Vivo.

Damage to peripheral nerves can cause debilitating consequences for patients such as lifelong pain and disability. At present, no drug treatments are routinely given in the clinic following a peripheral nerve injury (PNI) to improve regeneration and remyelination of damaged nerves. Appropriately targeted therapeutic agents have the potential to be used at different stages following nerve damage, e.g., to maintain Schwann cell viability, induce and sustain a repair phenotype to support axonal growth, or promote remyelination. The development of therapies to promote nerve regeneration is currently of high interest to researchers, however, translation to the clinic of drug therapies for PNI is still lacking. Studying the effect of PPARγ agonists for treatment of peripheral nerve injures has demonstrated significant benefits. Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), has reproducibly demonstrated benefits in vitro and in vivo, suggested to be due to its agonist action on PPARγ. Other NSAIDs have demonstrated differing levels of PPARγ activation based upon their affinity. Therefore, it was of interest to determine whether affinity for PPARγ of selected drugs corresponded to an increase in regeneration. A 3D co-culture in vitro model identified some correlation between these two properties. However, when the drug treatments were screened in vivo, in a crush injury model in a rat sciatic nerve, the same correlation was not apparent. Further differences were observed between capacity to increase axon number and improvement in functional recovery. Despite there not being a clear correlation between affinity and size of effect on regeneration, all selected PPARγ agonists improved regeneration, providing a panel of compounds that could be explored for use in the treatment of PNI.

Schisandrin B regulates macrophage polarization and alleviates liver fibrosis via activation of PPARγ.

BACKGROUND: Schisandrin B (Sch B), the main ingredient of Schisandra chinensis, displays many bioactivities. This study aimed to identify the drug target of Sch B against liver fibrosis and describe the related molecular mechanisms. METHODS: The effects of Sch B on liver fibrosis and macrophage polarization was investigated in vivo and in vitro. Furthermore, we analyzed the regulatory effect of Sch B on peroxisome proliferator-activated receptor gamma (PPARγ). RESULTS: Our data showed that Sch B dramatically alleviated liver inflammation and fibrosis and inhibited macrophage activation via PPARγ. Sch B binds with PPARγ by molecular docking. Immunofluorescence double staining showed that PPARγ was mainly expressed in macrophages rather than hepatic stellate cells (HSCs) in liver fibrosis. Importantly, Sch B strongly inhibited macrophage polarization in fibrotic livers compared with the model group. Further, the results revealed that Sch B efficiently inhibited macrophage polarization and also decreased the levels of inflammatory cytokines in vitro. Knockdown of PPARγ by small interfering RNA (siRNA) inhibited the effect of Sch B on macrophage polarization. Mechanistically, Sch B regulated macrophage polarization through inhibition of the nuclear factor (NF)-κB signaling pathway via PPARγ both in vivo and in vitro. CONCLUSIONS: These results suggested that Sch B alleviated carbon tetrachloride (CCl4)-induced liver inflammation and fibrosis by inhibiting macrophage polarization via targeting PPARγ.

Analysis of PPARγ Signaling Activity in Psoriasis.

In our previous work, we built the model of PPARγ dependent pathways involved in the development of the psoriatic lesions. Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear receptor and transcription factor which regulates the expression of many proinflammatory genes. We tested the hypothesis that low levels of PPARγ expression promote the development of psoriatic lesions triggering the IL17-related signaling cascade. Skin samples of normally looking and lesional skin donated by psoriasis patients and psoriatic CD3+ Tcells samples (n = 23) and samples of healthy CD3+ T cells donated by volunteers (n = 10) were analyzed by real-time PCR, ELISA and immunohistochemistry analysis. We found that the expression of PPARγ is downregulated in human psoriatic skin and laser treatment restores the expression. The expression of IL17, STAT3, FOXP3, and RORC in psoriatic skin before and after laser treatment were correlated with PPARγ expression according to the reconstructed model of PPARγ pathway in psoriasis.In conclusion, we report that PPARγ weakens the expression of genes that contribute in the development of psoriatic lesion. Our data show that transcriptional regulation of PPARγ expression by FOSL1 and by STAT3/FOSL1 feedback loop may be central in the psoriatic skin and T-cells.

Bis(ethylmaltolato)oxidovanadium (IV) attenuates amyloid-beta-mediated neuroinflammation by inhibiting NF-κB signaling pathway via a PPARγ-dependent mechanism.

Neuroinflammation plays a pivotal role in the pathophysiology of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. During brain neuroinflammation, activated microglial cells resulting from amyloid-beta (Aß) overload trigger toxic proinflammatory responses. Bis(ethylmaltolato)oxidovanadium (BEOV) (IV), an important vanadium compound, has been reported to have anti-diabetic, anti-cancer, and neuroprotective effects, but its anti-inflammatory property has rarely been investigated. In the present study, the inhibitory effects of BEOV on neuroinflammation were revealed in both Aß-stimulated BV2 microglial cell line and APPswe/PS1E9 transgenic mouse brain. BEOV administration significantly decreased the levels of tumor necrosis factor-α, interleukin-6, interleukin-1ß, inducible nitric oxide synthase, and cyclooxygenase-2 both in the hippocampus of APPswe/PS1E9 mice and in the Aß-stimulated BV2 microglia. Furthermore, BEOV suppressed the Aß-induced activation of nuclear factor-κB (NF-κB) signaling and upregulated the protein expression level of peroxisome proliferator-activated receptor gamma (PPARγ) in a dose-dependent manner. PPARγ inhibitor GW9662 could eliminate the effect of BEOV on Aß-induced NF-κB activation and proinflammatory mediator production. Taken altogether, these findings suggested that BEOV ameliorates Aß-stimulated neuroinflammation by inhibiting NF-κB signaling pathway through a PPARγ-dependent mechanism.

Pparγ1 Facilitates ErbB2-Mammary Adenocarcinoma in Mice.

HER2, which is associated with clinically aggressive disease, is overexpressed in 15-20% of breast cancers (BC). The host immune system participates in the therapeutic response of HER2+ breast cancer. Identifying genetic programs that participate in ErbB2-induced tumors may provide the rational basis for co-extinction therapeutic approaches. Peroxisome proliferator-activated receptor γ (PPARγ), which is expressed in a variety of malignancies, governs biological functions through transcriptional programs. Herein, genetic deletion of endogenous Pparγ1 restrained mammary tumor progression, lipogenesis, and induced local mammary tumor macrophage infiltration, without affecting other tissue hematopoietic stem cell pools. Endogenous Pparγ1 induced expression of both an EphA2-Amphiregulin and an inflammatory INFγ and Cxcl5 signaling module, that was recapitulated in human breast cancer. Pparγ1 bound directly to growth promoting and proinflammatory target genes in the context of chromatin. We conclude Pparγ1 promotes ErbB2-induced tumor growth and inflammation and represents a relevant target for therapeutic coextinction. Herein, endogenous Pparγ1 promoted ErbB2-mediated mammary tumor onset and progression. PPARγ1 increased expression of an EGF-EphA2 receptor tyrosine kinase module and a cytokine/chemokine 1 transcriptional module. The induction of a pro-tumorigenic inflammatory state by Pparγ1 may provide the rationale for complementary coextinction programs in ErbB2 tumors.

TWIST2 and the PPAR signaling pathway are important in the progression of nonalcoholic steatohepatitis.

BACKGROUND: To investigate the roles of the transcription factors twist family bHLH transcription factor 1 (TWIST1), twist family bHLH transcription factor 2 (TWIST2), and peroxisome proliferator activated receptor gamma (PPARγ) in the progression of nonalcoholic steatohepatitis. METHODS: The protein levels of TWIST1, TWIST2 and PPARγ were determined in the serum of nonalcoholic fatty liver disease (NAFLD) patients and healthy controls by enzyme-linked immunosorbent assay (ELISA). An in vivo model for fatty liver was established by feeding C57BL/6 J mice a high-fat diet (HFD). An in vitro model of steatosis was established by treating LO-2 cells with oleic acid (OA). RNA sequencing was performed on untreated and OA-treated LO-2 cells followed by TWIST1, TWIST2 and PPARγ gene mRNA levels analysis, Gene Ontology (GO) enrichment and pathway analysis. RESULTS: The TWIST2 serum protein levels decreased significantly in all fatty liver groups (P < 0.05), while TWIST1 varied. TWIST2 tended to be lower in mice fed an HFD and was significantly lower at 3 months. Similarly, in the in vitro model, the TWIST2 protein level was downregulated significantly at 48 and 72 h after OA treatment. RNA sequencing of LO-2 cells showed an approximately 2.3-fold decrease in TWIST2, with no obvious change in TWIST1 and PPARγ. The PPAR signaling pathway was enriched, with 4 genes upregulated in OA-treated cells (P = 0.0018). The interleukin (IL)-17 and tumor necrosis factor (TNF) signaling pathways were enriched in OA-treated cells. CONCLUSIONS: The results provide evidence that the TWIST2 and PPAR signaling pathways are important in NAFLD and shed light on a potential mechanism of steatosis.

Stimulation of Peroxisome Proliferator-Activated Receptor-Gamma (PPARγ) using Pioglitazone Decreases the Survival of Acute Promyelocytic Leukemia Cells through Up-Regulation of PTEN Expression.

BACKGROUND: The intertwining between cancer pathogenesis and aberrant expression of either oncogenes or tumor suppressor proteins ushered the cancer therapeutic approaches into a limitless road of modern therapies. For the nonce and among the plethora of promising anticancer agents, intense interest has focused on pioglitazone, a first in-class of Thiazolidinedione (TZD) drugs that is currently used to treat patients with diabetes. OBJECTIVE: Intrigued by the overexpression of PPARγ in Acute Promylocytic Leukemia (APL), this study was designed to investigate the effects of pioglitazone in APL-derived NB4 cells. METHODS: To assess the anti-leukemic effect of pioglitazone on myeloid leukemia cell lines, we used MTT and trypan blue assays. Given the higher expression level of PPARγ in NB4 cells, we then expanded our experiments on this cell line. To ascertain the molecular mechanism action of pioglitazone in APL-derived NB4 cells, we evaluated the expression levels of a large cohort of target genes responsible for the regulation of apoptosis, autophagy and cell proliferation. Afterward, to examine whether there is a correlation between PPARγ and the PI3K signaling pathway, the amount of Akt phosphorylation was evaluated using western blot analysis. RESULTS: Our results showed that pioglitazone exerted its cytotoxic effect in wild-type PTEN-expressing NB4 cells, but not in leukemic K562 cells harboring mutant PTEN; suggesting that probably this member of TZD drugs induced its anti-leukemic effects through a PTEN-mediated manner. Moreover, we found that not only pioglitazone reduced the survival rate of NB4 through the induction of p21-mediated G1 arrest, also elevated the intracellular level of Reactive Oxygen Species (ROS) which was coupled with upregulated FOXO3a. Notably, this study proposed for the first time that the stimulation of autophagy as a result of the compensatory activation of PI3K pathway may act as a plausible mechanism through which the anti-leukemic effect of pioglitazone may be attenuated; suggestive of the application of either PI3K or autophagy inhibitors along with pioglitazone in APL. CONCLUSION: By suggesting a mechanistic pathway, the results of the present study shed more light on the favorable anti-leukemic effect of pioglitazone and suggest it as a promising drug that should be clinically investigated in APL patients.

Linseed oil supplementation affects fatty acid desaturase 2, peroxisome proliferator activated receptor gamma, and insulin-like growth factor 1 gene expression in turkeys (Meleagris gallopavo).

OBJECTIVE: Effects of linseed oil (LO) supplementation on the fat content and fatty acid profile of breast meat, and the expression of three genes in the liver, breast muscle and fat tissues of commercial 154-day-old hybrid male turkeys were investigated. METHODS: The animals in the control group were fed a commercially available feed and received no LO supplementation (n = 70), whereas animals in the LO group (n = 70) were fed the same basic diet supplemented with LO (day 15 to 21, 0.5%; day 22 to 112, 1%). The effect of dietary LO supplementation on fatty acid composition of breast muscle was examined by gas chromatography, and the expression of fatty acid desaturase 2 (FADS2), peroxisome proliferator activated receptor gamma (PPARγ), and insulin-like growth factor 1 (IGF1) genes was analysed by means of quantitative reverse transcription polymerase chain reaction. RESULTS: The LO supplementation affected the fatty acid composition of breast muscle. Hepatic FADS2 levels were considerably lower (p<0.001), while adipose tissue expression was higher (p<0.05) in the control compared to the LO group. The PPARγ expression was lower (p<0.05), whereas IGF1 was higher (p<0.05) in the fat of control animals. There were no significant (p>0.05) differences in FADS2, PPARγ, and IGF1 gene expressions of breast muscle; however, omega-6/omega-3 ratio of breast muscle substantially decreased (p<0.001) in the LO group compared to control. CONCLUSION: Fatty acid composition of breast meat was positively influenced by LO supplementation without deterioration of fattening parameters. Remarkably, increased FADS2 expression in the liver of LO supplemented animals was associated with a significantly decreased omega-6/omega-3 ratio, providing a potentially healthier meat product for human consumption. Increased PPARγ expression in fat tissue of the LO group was not associated with fat content of muscle, whereas a decreased IGF1 expression in fat tissue was associated with a trend of decreasing fat content in muscle of the experimental LO group.

Garcinoic acid prevents ß-amyloid (Aß) deposition in the mouse brain.

Garcinoic acid (GA or δ-T3-13'COOH), is a natural vitamin E metabolite that has preliminarily been identified as a modulator of nuclear receptors involved in ß-amyloid (Aß) metabolism and progression of Alzheimer's disease (AD). In this study, we investigated GA's effects on Aß oligomer formation and deposition. Specifically, we compared them with those of other vitamin E analogs and the soy isoflavone genistein, a natural agonist of peroxisome proliferator-activated receptor γ (PPARγ) that has therapeutic potential for managing AD. GA significantly reduced Aß aggregation and accumulation in mouse cortical astrocytes. Similarly to genistein, GA up-regulated PPARγ expression and apolipoprotein E (ApoE) efflux in these cells with an efficacy that was comparable with that of its metabolic precursor δ-tocotrienol and higher than those of α-tocopherol metabolites. Unlike for genistein and the other vitamin E compounds, the GA-induced restoration of ApoE efflux was not affected by pharmacological inhibition of PPARγ activity, and specific activation of pregnane X receptor (PXR) was observed together with ApoE and multidrug resistance protein 1 (MDR1) membrane transporter up-regulation in both the mouse astrocytes and brain tissue. These effects of GA were associated with reduced Aß deposition in the brain of TgCRND8 mice, a transgenic AD model. In conclusion, GA holds potential for preventing Aß oligomerization and deposition in the brain. The mechanistic aspects of GA's properties appear to be distinct from those of other vitamin E metabolites and of genistein.

Additive anti-inflammation by a combination of conjugated linoleic acid and α-lipoic acid through molecular interaction between both compounds.

Alpha lipoic acid (LA) and conjugated linoleic acid (CLA) have been well-documented on a variety of functional effects in health foods. The main purpose of this study was focused on the additive anti-inflammatory activity of the combination of LA and CLA in vitro. Raw 264.7 cells induced by lipopolysaccharide were treated with LA and CLA individually or in combination at a variety of concentration ranges. Co-treating 25 µM of LA and 25 µM of CLA significantly inhibited pro-inflammatory cytokines compared to the same concentration of single LA- or CLA-treated group. The molecular mechanism of anti-inflammation by a combination of these compounds was attributed to extracellular signal-regulated kinase-1 (ERK1) and peroxisome proliferator-activated receptor gamma (PPARγ). Also, the molecular interaction between both compounds was confirmed by NMR. Our findings suggested that the combination of CLA and LA showed potential additive effect on anti-inflammation through the molecular interaction of both compounds.

Identification and Characterization of Cannabimovone, a Cannabinoid from Cannabis sativa, as a Novel PPARγ Agonist via a Combined Computational and Functional Study.

Phytocannabinoids (pCBs) are a large family of meroterpenoids isolated from the plant Cannabis sativa. Δ9-Tetrahydrocannabinol (THC) and cannabidiol (CBD) are the best investigated phytocannabinoids due to their relative abundance and interesting bioactivity profiles. In addition to various targets, THC and CBD are also well-known agonists of peroxisome proliferator-activated receptor gamma (PPARγ), a nuclear receptor involved in energy homeostasis and lipid metabolism. In the search of new pCBs potentially acting as PPARγ agonists, we identified cannabimovone (CBM), a structurally unique abeo-menthane pCB, as a novel PPARγ modulator via a combined computational and experimental approach. The ability of CBM to act as dual PPARγ/α agonist was also evaluated. Computational studies suggested a different binding mode toward the two isoforms, with the compound able to recapitulate the pattern of H-bonds of a canonical agonist only in the case of PPARγ. Luciferase assays confirmed the computational results, showing a selective activation of PPARγ by CBM in the low micromolar range. CBM promoted the expression of PPARγ target genes regulating the adipocyte differentiation and prevented palmitate-induced insulin signaling impairment. Altogether, these results candidate CBM as a novel bioactive compound potentially useful for the treatment of insulin resistance-related disorders.

Induction of peroxisome proliferator activated receptor γ (PPARγ) mediated gene expression and inhibition of induced nitric oxide production by Maerua subcordata (Gilg) DeWolf.

BACKGROUND: The health benefits of botanicals is linked to their phytochemicals that often exert pleiotropic effects via targeting multiple molecular signaling pathways such as the peroxisome proliferator-activated receptors (PPARs) and the nuclear factor kappaB (NFκB). The PPARs are transcription factors that control metabolic homeostasis and inflammation while the NF-κB is a master regulator of inflammatory genes such as the inducible nitric-oxide synthase that result in nitric oxide (NO) overproduction. METHODS: Extracts of Maerua subcordata (MS) and selected candidate constituents thereof, identified by liquid chromatography coupled to mass spectroscopy, were tested for their ability to induce PPARγ mediated gene expression in U2OS-PPARγ cells using luciferase reporter gene assay and also for their ability to inhibit lipopolysaccharide (LPS) induced NO production in RAW264.7 macrophages. While measuring the effect of test samples on PPARγ mediated gene expression, a counter assay that used U2OS-Cytotox cells was performed to monitor cytotoxicity or any non-specific changes in luciferase activity. RESULTS: The results revealed that the fruit, root, and seed extracts were non-cytotoxic up to a concentration of 30 g dry weight per litre (gDW/L) and induced PPARγ mediated gene expression but the leaf extract showed some cytotoxicity and exhibited minimal induction. Instead, all extracts showed concentration (1-15 gDW/L) dependent inhibition of LPS induced NO production. The root extract showed weaker inhibition. Among the candidate constituents, agmatine, stachydrine, trigonelline, indole-3-carboxyaldehyde, plus ethyl-, isobutyl-, isopropyl, and methyl-isothiocyanates showed similar inhibition, and most showed increased inhibition with increasing concentration (1-100 µM) although to a lesser potency than the positive control, aminoguanidine. CONCLUSION: The present study demonstrated for the first time the induction of PPARγ mediated gene expression by MS fruit, root, and seed extracts and the inhibition of LPS induced NO production by MS fruit, leaf, root, and seed extracts and some candidate constituents thereof.