PPARgamma Agonist Rosiglitazone Research Articles

A diet-independent zebrafish model for NAFLD recapitulates patient lipid profiles and offers a system for small molecule screening

Non-alcoholic Fatty Liver Disease (NAFLD) or pathological hepatic lipid overload, is considered to affect obese individuals. However, NAFLD in lean individuals is prevalent, especially in South Asian population. The pathophysiology of lean NAFLD is not well understood and most animal models of NAFLD use the high-fat diet paradigm. To bridge this gap, we have developed a diet-independent model of NAFLD in zebrafish. We have previously shown that chronic systemic inflammation causes metabolic changes in the liver leading to hepatic fat accumulation in an IL6 overexpressing (IL6-OE) zebrafish model. In the present study, we compared the hepatic lipid composition of adult IL6-OE zebrafish to the controls and found an accumulation of saturated triacylglycerols and a reduction in the unsaturated triacylglycerol species reminiscent of NAFLD patients. Zebrafish is an ideal system for chemical genetic screens. We tested whether the hepatic lipid accumulation in the IL6-OE is responsive to chemical treatment. We found that PPAR-gamma agonist Rosiglitazone, known to reduce lipid overload in the high-fat diet models of NAFLD, could ameliorate the fatty liver phenotype of the IL6-OE fish. Rosiglitazone treatment reduced the accumulation of saturated lipids and showed a concomitant increase in unsaturated TAG species in our inflammation-induced NAFLD model. Our observations suggest that the IL6-OE model can be effective for small molecule screening to identify compounds that can reverse hepatic lipid accumulation, especially relevant to lean NAFLD.

MON-LB77 Inhibitors of XIAP as Novel Therapeutic Agents in Thyroid Cancer

Treatment options for radioiodine-refractory epithelial thyroid cancer (ETC) are limited to tyrosine kinase inhibitors (TKIs), which are associated with significant adverse effects and are not curative. The inhibitors of apoptosis (IAP) family have oncogenic properties and overexpression of X-linked IAP (XIAP) in papillary thyroid carcinoma (PTC) is associated with a poor prognosis. Our group has previously reported a synergistic interaction between SMAC mimetics (SM) (IAP antagonists with XIAP and cIAP1 specificity), and PPARgamma agonists in granulosa cell tumors (1). Such an approach has not been explored in ETC.We hypothesize that SM may be efficacious alone or in combination with a secondary agent to inhibit proliferation, induce cell death and/or promote differentiation to resensitize cells to radioiodine.Four ETC-derived cell lines (K1, Nthy-ori 3-1, TPC-1 and SW-1736) were examined for cIAP1, cIAP2 and XIAP expression by RT-PCR. The K-1 and TPC-1 cell lines (PTC origin, BRAFV600E and PI3KCA mutation positive) were chosen to investigate the effects of an SM in combination with either a PPARgamma agonist (rosiglitazone) or a broad-spectrum TKI (sorafenib). Cell proliferation was examined using xCELLigence Real-Time Cell Analysis. Viability was assessed using total cell counts at 24 and 48 hours.In the four cell lines, we found abundant cIAP1 and XIAP expression and low cIAP2 expression. When an SM was used in combination with either rosiglitazone or sorafenib, we observed significant impairment of cell proliferation and viability with a clear morphological response. These effects appear SM-dependent, as SM treatment alone also showed significant effects on proliferation. However, these effects were enhanced when combined with sorafenib, which was ineffective alone. Markers of differentiation are currently being examined.Our findings suggest a novel role for SM in treating or redifferentiating radioiodine-refractory ETC. Clinically, this may involve lower doses of individual agents than when used alone, thereby reducing adverse effects.

Treating prediabetes: why and how should we do it?

Prediabetes is the subclinical impairment in fasting plasma glucose, impaired glucose tolerance or both. The degree of impairment is between euglycemia and the hyperglycemia of type 2 diabetes (T2DM). Prediabetes is not considered benign, because it is a risk factor for T2DM but is also associated with micro and macrovascular complications. Lifestyle interventions including diet and exercise are first-line treatments. Medications can also play a role, as randomized controlled trials of biguanides (metformin) alpha-glucosidase inhibitors (Acarbose), inhibitors of pancreatic lipase (Orlistat), PPAR-gamma agonists (Rosiglitazone, Pioglitazone), meglitinides (Nateglinide) and GLP-1 receptor agonists (Liraglutide) have all shown benefits. Bariatric surgery is another efficacious means of preventing T2DM in patients with prediabetes and obesity. Prediabetes in its various guises is a risk factor for the future development T2DM and diabetic complications. Importantly the prediabetic state is amenable to interventions that prevent/delay transition to overt T2DM. Knowledge gaps exist regarding how best to make prognostication highly sensitive and specific as to which patient will develop T2DM. Moreover, understanding of phenotype specific pathophysiology may add value to funding appropriate interventions for patients with prediabetes. Management of patients with prediabetes should be individualized based on the algorithms that predict phenotype specific risk and allow for the use of phenotype tailored interventions.

PPAR gamma agonist rosiglitazone switches fuel preference to lipids in promoting adaptive thermogenesis under cold exposure

PPAR gamma agonist rosiglitazone switches fuel preference to lipids in promoting adaptive thermogenesis under cold exposure

A PPAR-Gamma Agonist Rosiglitazone Suppresses Fibrotic Response in Human Pterygium Fibroblasts by Modulating the p38 MAPK Pathway.

Fibroblast activation may play an important role in pterygium progression. Synthetic peroxisome proliferator-activated receptor γ (PPAR-γ) ligands have been shown to be effective antifibrotic agents against transforming growth factor β1 (TGF-β1) induced fibrosis in several tissues. We aimed to investigate the antifibrotic effects of the PPAR-γ ligand rosiglitazone in pterygium fibroblasts and the underlying mechanisms. Profibrotic activation was induced by TGF-β1 in primary cultured human pterygium fibroblasts and the effect of rosiglitazone treatment on α-smooth muscle actin (α-SMA), and extra cellular matrix proteins synthesis was detected by western blotting, real-time PCR, immunostaining, and flow cytometry. Pharmaceutical inhibition of PPAR-γ receptor was used to determine the dependency or otherwise of rosiglitazone's action on PPAR-γ signaling. Major signaling pathways downstream of TGF-β1 were investigated by western blotting to assess their possible association with rosiglitazone's effect. Cell viability and apoptosis were investigated to assess drug-induced cytotoxicity, and the effect of rosiglitazone treatment on cell migration was further determined. α-SMA and fibronectin synthesis induced by TGF-β1 were suppressed by rosiglitazone treatment in a dose-dependent manner. Rosiglitazone also inhibited intrinsic TGF-β1 expression. Smad2/3, ERK1/2, and P38 pathways were activated in response to TGF-β1. Rosiglitazone suppressed TGF-β1-induced P38 MAPK activation, while ERK1/2 and Smad2/3 signaling remained unaffected. The observed antifibrotic effect of rosiglitazone was not affected by the PPAR-γ antagonist GW9662, indicating it is not PPAR-γ dependent. Rosiglitazone also inhibited the proliferation and migration of pterygium fibroblasts. Rosiglitazone suppresses TGF-β1-induced myofibroblast activation and extra cellular matrix synthesis in pterygium fibroblasts at least partly through the modulation of the p38 MAPK pathway.

A PPAR gamma agonist protects against oral mucositis induced by irradiation in a murine model

BackgroundDue to its anti-inflammatory, antifibrotic and antineoplastic properties, the PPAR gamma agonist rosiglitazone is of interest in prevention and therapy of radiation-induced toxicities. We aimed to evaluate the radioprotective effect of rosiglitazone in a mouse model of radiation-induced oral mucositis. Material and methodsOral mucositis was obtained by irradiation of the oral region of C57BL/6J mice, pretreated or not with rosiglitazone. Mucositis was assessed by macroscopic scoring, histology and molecular analysis. Tumor xenograft was obtained by s.c. injection of Hep-2 cells in CD1 mice. Tumor volume was measured twice a week to evaluate effect of rosiglitazone alone and combined with radiotherapy. ResultsIrradiated mice showed typical features of oral mucositis, such as oedema and reddening, reaching the peak of damage after 12–15days. Rosiglitazone markedly reduced visible signs of mucositis and significantly reduced the peak. Histological analysis showed the presence of an inflammatory cell infiltrate after irradiation; the association with rosiglitazone noticeably reduced infiltration. Rosiglitazone significantly inhibited radiation-induced tnfα, Il-6 and Il-1β gene expression. Rosiglitazone controlled the increase of TGF-β and NF-kB p65 subunit proteins induced by irradiation, and enhanced the expression of catalase. Irradiation and rosiglitazone significantly reduced tumor volume as compared to control. Rosiglitazone did not protect tumor from the therapeutic effect of radiation. ConclusionRosiglitazone exerted a protective action on normal tissues in radiation-induced mucositis. Moreover, it showed antineoplastic properties on head-neck carcinoma xenograft model and selective protection of normal tissues. Thus, PPAR gamma agonists should be further investigated as radioprotective agents in head and neck cancer.

Rosiglitazone promotes the differentiation of Langerhans cells and inhibits that of other dendritic cell types from CD133 positive hematopoietic precursors.

Dendritic cells and their precursors express PPAR-gamma, whose stimulation has inhibitory effects on the maturation and function of dendritic cells in vivo. Dendritic cells can differentiate in vitro from CD133+ progenitors; the influence of PPAR-gamma stimulation on this process is unknown. We have addressed the effect of PPAR-gamma agonist rosiglitazone, at a concentration as used in clinics, on the differentiation of dendritic cells from human CD133+ progenitors. Cells were harvested from cord blood by density gradient and immunomagnetic separation, and cultured for 18 days with fetal calf serum, cytokines and 1 μmol/L rosiglitazone. Analyses included flow cytometry, electron microscopy and mixed lymphocyte reaction. As expected, control cells generated without rosiglitazone were dendritic, expressed MHC-II, CD80, CD83 and CD86 and stimulated mixed reaction potently. A minority of cells expressed the Langerhans cell marker CD207/langerin, but none contained Birbeck granules. With rosiglitazone much fewer cells were generated; they were all dendritic, expressed differentiation and maturation-related antigens in higher percentage and were better stimulators of lymphocytes than those generated without the drug. The vast majority of cells expressed CD207/langerin and many contained Birbeck granules, i.e. were full-fledged Langerhans cells. We conclude that stimulation of PPAR-gamma, while negatively affecting the number of generated cells, promotes the maturation of human cord blood CD133 positive precursors into efficient, immunostimulating dendritic cells with a Langerhans cell phenotype.

THU0036 PPAR gamma agonist rosiglitazone could inhibit RA-FLS induced osteoclastogenesis by down-regulating RANKL expression and suppression of ERK phosphorylation

BackgroundExperiments and clinical trial have shown that peroxisome proliferator-activated receptor-γ (PPAR-γ) agonist could inhibit inflammation in rheumatoid arthritis (RA)[1,2]. Recent reports also showed that PPAR-γ agonist could prevent inflammatory periodontal...

Targeting peroxisome proliferator-activated receptors (ppar) for the treatment l-dopa-induced dyskinesias

L administration of L-DOPA to Parkinson’s disease (PD) patients is accompanied by fluctuations in its duration of action and chorea-like motor complications known as L-DOPA-induced dyskinesias (LID). As L-DOPA is the most effective treatment for PD, there is a strong need to identify new pharmacological targets to control LID while maintaining L-DOPA beneficial effects.LID can be modeled in rats with unilateral 6-OHDA lesions via chronic administration of L-DOPA, which induces increasingly severe axial, limb and oro-facial abnormal involuntary movements (AIMs). Previous studies in our laboratory showed that systemic administration of the PPAR gamma agonist rosiglitazone (5 & 10 mg/kg, i.p.) ameliorated axial, oral and limb AIMs without reducing L-DOPA’s anti-parkinsonian activity. Rosiglitazone also attenuated the L-DOPA-induced elevation of dyskinesia (Zif-268 and prodynorphin) and inflammation (COX-2) markers within the denervated striatum. Interestingly, chronic L-DOPA significantly increased the PPAR beta/delta isoform in dyskinetic rats and this elevation was reversed by rosiglitazone treatment. These data suggest that targeting PPAR gamma/delta receptors can ameliorate dyskinetic symptoms, possibly by reducing the underlying neuroinflammatory response observed in PD. Supported by RO1 -NS050401-06 (A.G).

56. Age dependant effects of the PPAR-gamma agonist rosiglitazone on the brain and periphery during systemic LPS-induced inflammation in rats

Aging is associated with altered immune responses to stimuli such as lipopolysaccharide (LPS) and a mitochondrial decline is proposed to be a main underlying factor in age-related diseases. Recently, rosiglitazone (RZG), a peroxisome proliferator-activated receptor (PPAR) gamma agonist was shown to exert anti-inflammatory properties and to induce a key regulator of mitochondrial biogenesis, namely, PPARgamma co-activator-1-alpha (PGC-1alpha). Here, we aimed to further elucidate age-dependent changes in signaling pathways and sickness response during LPS-induced inflammation and to test potential beneficial effects of rosiglitazone. Pretreatment of old (24 months) and young (2 months) rats with RZG or solvent was followed by intraperitoneal injection of LPS (100 μg/kg) or saline. 24 h after stimulation blood, brain and liver were withdrawn for further analysis. We found age-dependent differences in fever and severity of other sickness symptoms after LPS-stimulation. Pretreatment with rosiglitazone, however, did not alter this response in young or old rats. Nevertheless, analysis of the liver by RT-PCR revealed increased mRNA-levels of markers of mitochondrial biogenesis in saline-injected and RZG-pretreated animals. Interestingly, several plasma cytokines including interleukin (IL)-6, IL-10, and IL-1ra and brain/liver inflammatory mediators such as nuclear factor IL-6 showed age-dependent changes independent of RZG-injections. Overall, beneficial effects of RZG could not be revealed in the current experimental paradigm. Nonetheless, our results reveal further insights into changes of brain and peripheral inflammatory mediators during aging and LPS-induced inflammation.

Rosiglitazone Improves Survival and Hastens Recovery from Pancreatic Inflammation in Obese Mice

Obesity increases severity of acute pancreatitis (AP) by unclear mechanisms. We investigated the effect of the PPAR-gamma agonist rosiglitazone (RGZ, 0.01% in the diet) on severity of AP induced by administration of IL-12+ IL-18 in male C57BL6 mice fed a low fat (LFD) or high fat diet (HFD), under the hypothesis that RGZ would reduce disease severity in HFD-fed obese animals. In both LFD and HFD mice without AP, RGZ significantly increased body weight and % fat mass, with significant upregulation of adiponectin and suppression of erythropoiesis. In HFD mice with AP, RGZ significantly increased survival and hastened recovery from pancreatic inflammation, as evaluated by significantly improved pancreatic histology, reduced saponification of visceral adipose tissue and less severe suppression of erythropoiesis at Day 7 post-AP. This was associated with significantly lower circulating and pancreas-associated levels of IL-6, Galectin-3, osteopontin and TIMP-1 in HFD + RGZ mice, particularly at Day 7 post-AP. In LFD mice with AP, RGZ significantly worsened the degree of intrapancreatic acinar and fat necrosis as well as visceral fat saponification, without affecting other parameters of disease severity or inflammation. Induction of AP lead to major suppression of adiponectin levels at Day 7 in both HFD and HFD + RGZ mice. In conclusion, RGZ prevents development of severe AP in obese mice even though it significantly increases adiposity, indicating that obesity can be dissociated from AP severity by improving the metabolic and inflammatory milieu. However, RGZ worsens selective parameters of AP severity in LFD mice.

Modified Low Density Lipoproteins Decrease the Activity and Expression of Lysosomal Acid Lipase in Human Endothelial and Smooth Muscle Cells

Lysosomal acid lipase (LAL), the only lysosomal enzyme involved in the hydrolysis of LDL-cholesteryl esters, is a key regulator of cellular cholesterol and fatty acid homeostasis and its deficiency contributes to the pathophysiology of various diseases. In this study, we questioned whether oxidized or glycated LDL, a common occurrence in atherosclerosis and diabetes, affect the activity and expression of LAL in vascular endothelial cells (EC) and smooth muscle cells (SMC). LAL activity and expression were assayed in cultured human EC and SMC exposed to oxidized LDL (oxLDL), (±)9-hydroxyoctadecadienoic acid-cholesteryl ester (HODE), glycated LDL (gLDL), or native LDL (nLDL) as control, in the presence or absence of LXR or PPAR-gamma agonists. We found that LAL activity and expression were significantly down regulated by oxLDL and HODE in EC, and by gLDL in SMC. The LXR agonist T0901317 reversed the decreased LAL expression in modified LDL- or HODE-exposed EC (P<0.001) and in gLDL-exposed SMC, whereas PPAR-gamma agonist rosiglitazone induced a low effect only in EC. In conclusion, modified LDL down regulates LAL expression in human EC and SMC by a process involving the LXR signaling pathway. This is the first demonstration that modified LDL modulate LAL expression, in a cell specific manner.

Therapeutic potential of peroxisome proliferator-activated receptor gamma agonist rosiglitazone in cerebral vasospasm after a rat experimental subarachnoid hemorrhage model

The pathogenesis of cerebral vasospasm is closely associated with inflammation and immune response in arterial walls. Recently, the authors proved the key role of Toll-like receptor (TLR)4 in the development of vasospasm in experimental subarachnoid hemorrhage (SAH) model. Because peroxisome proliferator-activated receptor (PPAR) gamma agonists are identified as effective inhibitors of TLR4 activation, we investigated the anti-inflammation properties of PPAR-gamma agonist rosiglitazone in basilar arteries in a rat experimental SAH model and evaluated the effects of rosiglitazone on vasospasm. Inflammatory responses in basilar arteries were assessed by immunohistochemical staining for intercellular molecule (ICAM)-1 and myeloperoxidase (MPO). Expression of TLR4 was determined by western blot analysis. The degree of cerebral vasospasm was evaluated by measuring the mean diameter and cross-sectional area of basilar arteries. Rosiglitazone suppressed the SAH-induced inflammatory responses in basilar arteries by inhibiting the TLR4 signalling. Furthermore, rosiglitazone could attenuate cerebral vasospasm following SAH. Therefore, we suggested that PPAR-gamma agonists may be potential therapeutic agents for cerebral vasospasm.

Adipokine expression and secretion by canine adipocytes: stimulation of inflammatory adipokine production by LPS and TNFα

Adiposity and obesity are increasing in dogs. We have examined here the endocrine function of canine adipose tissue and the regulation of production of inflammation-related adipokines by dog adipocytes. Adiponectin, leptin, IL-6, MCP-1 and TNFalpha genes were expressed in the main adipose depots of dogs, but there were no major depot differences in mRNA levels. Each adipokine was expressed in canine adipocytes differentiated in culture and secreted into the medium (leptin undetected). IL-6, MCP-1 and TNFalpha were also expressed and secreted by preadipocytes; adiponectin and leptin were only expressed after adipocyte differentiation. The inflammatory mediators LPS and TNFalpha had major stimulatory effects on the expression and secretion of IL-6, MCP-1 and TNFalpha; there was a >5,000-fold increase in IL-6 mRNA level with LPS. IL-6 release into the medium was increased >50-fold over 24 h with LPS and TNFalpha, while MCP-1 release was increased 23- and 40-fold by TNFalpha and LPS, respectively. However, there was no effect, or small reductions, in adiponectin and leptin mRNA levels with the inflammatory mediators. Dexamethasone-stimulated leptin gene expression, had no effect on adiponectin expression, but decreased the expression and secretion of IL-6 and MCP-1. The PPARgamma agonist rosiglitazone stimulated both adiponectin and leptin expression and inhibited the expression of IL-6, MCP-1 and TNFalpha; MCP-1 secretion was reduced. These results demonstrate that canine adipocytes express and secrete key adipokines and show that adipocytes of this species are highly responsive to inflammatory mediators with the induction of major increases in the production of inflammation-related adipokines.

Heme oxygenase‐1/p21WAF1 mediates peroxisome proliferator‐activated receptor‐γ signaling inhibition of proliferation of rat pulmonary artery smooth muscle cells

Activation of peroxisome proliferator-activated receptor (PPAR)-gamma suppresses proliferation of rat pulmonary artery smooth muscle cells (PASMCs), and therefore ameliorates the development of pulmonary hypertension in animal models. However, the molecular mechanisms underlying this effect remain largely unknown. This study addressed this issue. The PPARgamma agonist rosiglitazone dose-dependently stimulated heme oxygenase (HO)-1 expression in PASMCs, 5 microm rosiglitazone inducing a 12.1-fold increase in the HO-1 protein level. Cells pre-exposed to rosiglitazone showed a dose-dependent reduction in proliferation in response to serotonin; this was abolished by pretransfection of cells with sequence-specific small interfering RNA against HO-1. In addition, rosiglitazone stimulated p21(WAF1) expression in PASMCs, a 2.34-fold increase in the p21(WAF1) protein level being achieved with 5 microm rosiglitazone; again, this effect was blocked by knockdown of HO-1. Like loss of HO-1, loss of p21(WAF1) through siRNA transfection also reversed the inhibitory effect of rosiglitazone on PASMC proliferation triggered by serotonin. Taken together, our findings suggest that activation of PPARgamma induces HO-1 expression, and that this in turn stimulates p21(WAF1) expression to suppress PASMC proliferation. Our study also indicates that rosiglitazone, a medicine widely used in the treatment of type 2 diabetes mellitus, has potential benefits for patients with pulmonary hypertension.

In vivo effects of rosiglitazone in a human neuroblastoma xenograft

Background:Neuroblastoma (NB) is the most common extra-cranial solid tumour in infants. Unfortunately, most children present with advanced disease and have a poor prognosis. There is in vitro evidence that the peroxisome proliferator-activated receptor γ (PPARγ) might be a target for pharmacological intervention in NB. We have previously demonstrated that the PPARγ agonist rosiglitazone (RGZ) exerts strong anti-tumoural effects in the human NB cell line, SK-N-AS. The aim of this study was to evaluate whether RGZ maintains its anti-tumoural effects against SK-N-AS NB cells in vivo.Methods and results:For this purpose, tumour cells were subcutaneously implanted in nude mice, and RGZ (150 mg kg−1) was administered by gavage daily for 4 weeks. At the end of treatment, a significant tumour weight inhibition (70%) was observed in RGZ-treated mice compared with control mice. The inhibition of tumour growth was supported by a strong anti-angiogenic activity, as assessed by CD-31 immunostaining in tumour samples. The number of apoptotic cells, as determined by cleaved caspase-3 immunostaining, seemed lower in RGZ-treated animals at the end of the treatment period than in control mice, likely because of the large tumour size observed in the latter group.Conclusions:To our knowledge, this is the first demonstration that RGZ effectively inhibits tumour growth in a human NB xenograft and our results suggest that PPARγ agonists may have a role in anti-tumoural strategies against NB.

Kinetic Assessment and Therapeutic Modulation of Metabolic and Inflammatory Profiles in Mice on a High-Fat and Cholesterol Diet

The kinetics of metabolic and inflammatory parameters associated with obesity were evaluated in a murine diet-induced obesity (DIO) model using a diet high in fat and cholesterol. Cellular infiltration and mediator production were assessed and shown to be therapeutically modulated by the PPARgamma agonist rosiglitazone. C57BL/6 mice were maintained on a 45% fat/ 0.12% cholesterol (HF/CH) or Chow diet for 3, 6, 16, or 27 weeks. Flow cytometry was employed to monitor peripheral blood monocytes and adipose tissue macrophages (ATM). Gene expression and protein analysis methods were used to evaluate mediator production from total epididymal fat (EF), stromal vascular fraction (SVF), and sorted SVF cells. To investigate therapeutic intervention, mice were fed a HF/CH diet for 12 weeks and then a diet formulated with rosiglitazone (5 mg/kg) for an additional 6 weeks. A HF/CH diet correlated with obesity and a dramatic proinflammatory state. Therapeutic intervention with rosiglitazone attenuated the HF/CH induced inflammation. In addition, a novel population was found that expressed the highest levels of the pro-inflammatory mediators CCL2 and IL-6.

PPARγ agonists inhibit angiogenesis by suppressing PKCα- and CREB-mediated COX-2 expression in the human endothelium

The activation of peroxisome proliferator-activated receptor (PPAR)gamma is known to inhibit angiogenesis. As a potential mechanism for this, we aimed at examining the effects of PPARgamma agonists on the pro-angiogenic enzyme cyclooxygenase (COX)-2 in human endothelium. Cultured endothelial cells were pre-incubated with the PPARgamma agonists rosiglitazone (RSG) or GW1929 before stimulation with vascular endothelial growth factor (VEGF) or phorbol myristate acetate (PMA). RSG and GW1929 attenuated VEGF- and PMA-stimulated COX-2 activity, as well as protein and mRNA expression. This effect was abolished by the PPARgamma antagonists bisphenol A diglycidyl ether and GW9662 as well as by PPARgamma small-interfering RNAs (siRNAs). Transient transfection experiments revealed that the induction of COX-2 promoter was significantly inhibited by RSG through an interference with the cAMP response element (CRE) site. COX-2 downregulation after siRNA targeting CRE-binding protein (CREB) confirmed the role of CREB in mediating COX-2 transcription. Correspondingly, PPARgamma agonists attenuated CREB activation. As both protein kinase C (PKC)alpha and beta are involved in VEGF-induced COX-2 expression and CREB activation, we investigated which isoform(s) of PKC was affected by RSG. RSG only reduced VEGF- and PMA-stimulated PKCalpha membrane translocation. VEGF induces CREB-mediated COX-2 expression through a PKCalpha-dependent pathway in human endothelium. The anti-angiogenic effect of PPARgamma agonists is due, at least in part, to an interference with the VEGF-stimulated PKCalpha-mediated activation of CREB and the related expression of COX-2.

Pparγ2 Is a Key Driver of Longevity in the Mouse

Aging involves a progressive physiological remodeling that is controlled by both genetic and environmental factors. Many of these factors impact also on white adipose tissue (WAT), which has been shown to be a determinant of lifespan. Interrogating a transcriptional network for predicted causal regulatory interactions in a collection of mouse WAT from F2 crosses with a seed set of 60 known longevity genes, we identified a novel transcriptional subnetwork of 742 genes which represent thus-far-unknown longevity genes. Within this subnetwork, one gene was Pparg (Nr1c3), an adipose-enriched nuclear receptor previously not associated with longevity. In silico, both the PPAR signaling pathway and the transcriptional signature of Pparγ agonist rosiglitazone overlapped with the longevity subnetwork, while in vivo, lowered expression of Pparg reduced lifespan in both the lipodystrophic Pparg1/2-hypomorphic and the Pparg2-deficient mice. These results establish Pparγ2 as one of the determinants of longevity and suggest that lifespan may be rather determined by a purposeful genetic program than a random process.

P2.122 PPAR-gamma agonist rosiglitazone stops the progressive dopaminergic degeneration induced by chronic MPTP in mice

P2.122 PPAR-gamma agonist rosiglitazone stops the progressive dopaminergic degeneration induced by chronic MPTP in mice