Molecular mechanism of benign biliary stricture inhibition by rosiglitazone-activated peroxisome proliferator-activated receptor gamma

SUMMARY OBJECTIVE: The aim of this study was to investigate whether rosiglitazone-activated peroxisome proliferator-activated receptor gamma can inhibit the occurrence of benign biliary stricture and further elucidate the relevant molecular signaling mechanism. METHODS: The primary cultured rat biliary fibroblasts following experiments were performed using within the fifth generation cells, which were separated from the bile ducts of Sprague-Dawley rats. The primary cultured rat biliary fibroblasts were co-cultured with 10 ng/mL transforming growth factor-beta 1 for stimulating collagen formation. Competent cells were transfected with siRNA that specifically target Smad3 or connective tissue growth factor to inhibit the expression of the corresponding proteins. The cells were incubated with 10 μmol/L rosiglitazone to activate peroxisome proliferator-activated receptor gamma. The cells were incubated with 10 μmol/L GW9662 in the pretreatment session to inactivate peroxisome proliferator-activated receptor gamma. ELISA was used to determine the levels of connective tissue growth factor and type I collagen in the cell supernatant. Western blotting was used to detect the levels of intracellular p-Smad3/t-Smad3. RESULTS: Rosiglitazone-activated peroxisome proliferator-activated receptor gamma inhibited the secretion of type I collagen induced by transforming growth factor-beta 1. Peroxisome proliferator-activated receptor gamma inhibitor GW9662 could significantly reverse the rosiglitazone-triggered inhibition of transforming growth factor-beta 1-induced type I collagen secretion by suppressing peroxisome proliferator-activated receptor gamma activation (p<0.01). Furthermore, we also found that the activation of peroxisome proliferator-activated receptor gamma was accompanied by the inhibition of transforming growth factor-beta 1-induced Smad3 phosphorylation (p<0.01), increased connective tissue growth factor expression (p<0.01), and production of type I collagen (p<0.01), all of which effects elicited by rosiglitazone could be reversed by peroxisome proliferator-activated receptor gamma inhibitor GW9662. CONCLUSION: Peroxisome proliferator-activated receptor gamma activated by rosiglitazone inhibits the transforming growth factor-beta1 -induced phosphorylation of Smad3 and the increased connective tissue growth factor expression as well as inhibits the secretion of type I collagen in biliary fibroblasts.

Type II diabetes mellitus and obesity: Common links, existing therapeutics and future developments

Type II diabetes mellitus (T2DM) and obesity are two common pathophysiological conditions of metabolic syndrome(MetS), a collection of similar metabolic dysfunctions due to sedentary lifestyle and overnutrition. Obesity arises fromimproper adipogenesis which otherwise has a crucial role in maintaining proper metabolic functions. Downstream eventsarising from obesity have been linked to T2DM. The nuclear receptor peroxisome proliferator activator gamma (PPAR-c),responsible for maintaining lipid and glucose homeostasis, is down-regulated under obesity leading to a weakened insulinsensitivity of the human body. In course of our review we will outline details of the down-regulation mechanism, provide anoverview of the current clinical therapeutics and their shortcomings. Toxicity studies on the seminal drug troglitazone,belonging to the most effective glitazone anti-diabetic category, is also discussed. This will lead to an overview aboutstructural adaptations on the existing glitazones to alleviate their side effects and toxicity. Finally, we forward a concept ofnovel therapeutics mimicking the glitazone framework, based on some design concepts and preliminary in silico studies.These could be later developed into dual acting drugs towards alleviating the deleterious effects of obesity on normalglucose metabolism, and address obesity in itself.

Total synthesis of cyclodepsipeptide Hikiamides A-C / 中国药科大学学报

@#Total synthesis of cyclodepsipeptide Hikiamides A-C was described. Fragment convergent condensation method was applied for the preparation of Hikiamides A-C, starting from Commercially available amino acid such as L-N-Boc-Phe-OH, L-N-Boc-Trp-OH, L-N-Cbz-Van-OH etc. Tripeptide fragments(compounds 5a/5b)and dipeptide fragments(compounds 8a/8b)were first prepared. The subsequent condensation of the resulted two fragments provided protected linear pentapetides(compounds 9a/9b/9c); Finally, the linear pentapetide was cyclized by a mixed condensing agents comprised of PyBOP and HBTU. Hikiamides A-C was obtained with total yields of 9%, 11% and 6. 5%, respectively. Compared with the natural source, this method has the advantages of low cost, convenient operation and high yield, which effectively solves the problem of low isolated yield of Hikiamides A-C from Fusarium sp.

Clinical Significance of Peroxisome Proliferator-Activated Receptor gamma and TRAP220 in Patients with Operable Colorectal Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that regulates expression of mediators of lipid metabolism and the inflammatory response. Thyroid hormone receptor-associated proteins 220 (TRAP220) is an essential component of the TRAP/Mediator complex. The objective of this study was to clarify whether PPARgamma or TRAP220 are significant prognostic markers in resectable colorectal cancer (CRC). MATERIALS AND METHODS: A total of 399 patients who underwent curative resection for CRC were enrolled. We investigated the presence of PPARgamma and TARP220 in CRC tissues and adjacent normal tissues by immunohistochemistry. Correlation between the expression of these factors and clinicopathologic features and survival was investigated. RESULTS: Median age of the patients was 63 years (range, 22 to 87 years), and median follow-up duration 61.1 months (range, 2 to 114 months). PPARgamma and TRAP220 expression showed significant correlation with depth of invasion (p=0.013 and p=0.001, respectively). Expression of TRAP220 also showed association with lymph node metastasis and TNM stage (p=0.001). Compared with patients with TRAP220 negative tumors, patients with TRAP220 positive tumors had longer 5-year disease-free survival (DFS) tendency (p=0.051). Patients who were PPARgamma positive combined with TRAP220 positive had a better 5-year DFS (64.8% vs. 79.3%, p=0.013). In multivariate analysis expression of both PPARgamma and TRAP220 significantly affected DFS (hazard ratio, 0.620; 95% confidence interval, 0.379 to 0.997; p=0.048). CONCLUSION: TRAP220 may be a valuable marker for nodal metastasis and TNM stage. Tumor co-expression of PPARgamma and TRAP220 represents a biomarker for good prognosis in CRC patients.

Ciglitazone, a Peroxisome Proliferator-Activated Receptor Gamma Ligand, Inhibits Proliferation and Differentiation of Th17 Cells

Peroxisome proliferator-activated receptor gamma (PPARgamma) was identified as a cell-intrinsic regulator of Th17 cell differentiation. Th17 cells have been associated with several autoimmune diseases, including experimental autoimmune encephalomyelitis (EAE), inflammatory bowel disease (IBD), and collagen-induced arthritis. In this study, we confirmed PPARgamma-mediated inhibition of Th17 cell differentiation and cytokine production at an early stage. Treatment with ciglitazone, a PPARgamma ligand, reduced both IL-1beta-mediated enhancement of Th17 differentiation and activation of Th17 cells after polarization. For Th17 cell differentiation, we found that ciglitazone-treated cells had a relatively low proliferative activity and produced a lower amount of cytokines, regardless of the presence of IL-1beta. The inhibitory activity of ciglitazone might be due to decrease of CCNB1 expression, which regulates the cell cycle in T cells. Hence, we postulate that a pharmaceutical PPARgamma activator might be a potent candidate for treatment of Th17-mediated autoimmune disease patients.

Improved adipogenic in vitro differentiation: comparison of different adipogenic cell culture media on human fat and bone stroma cells for fat tissue engineering / 대한해부학회지

To date there is no sufficient in vitro fat tissue engineering and a protocol has not been well established for this purpose. Therefore, we evaluated the in vitro influence of two different adipogenic growth media for their stimulation potential on different cell lineages to clearly define the most potent adipogenic growth media for future in vitro tissue engineering approaches. The samples for differentiation were composed of human adipogenic-derived stroma cells (hADSCs) and human bone marrow mesenchymal stroma cells (hMSCs). A normal adipogenic medium (NAM) and a specific adipogenic medium (SAM) were tested for their adipogenic stimulation potential. After 10 days and 21 days the relative gene expression was measured for the adipogenic marker genes PPARgamma2, C/EBPalpha, FABP4, LPL, and GLUT4 detected through real time reverse transcriptase polymease chain reaction (RT-PCR). Other study variables were the comparison between NAM and SAM and between the used cells hADSCs and hMSCs. Additionally an Oil-Red staining was performed after 21 days. Our results revealed that only SAM was significantly (P<0.05) superior in the differentiation process in contrast to NAM for 10 days and 21 days. As well was SAM superior to differentiate the used cell lineages. This was evaluated by the detected marker genes PPARgamma2, C/EBPalpha, FABP4, LPL, and GLUT4 through real time RT-PCR and by Oil-Red staining. In addition, the hMSCs proofed to be equal donor cells for adipogenic differentiation especially when stimulated by SAM. The results suggest that the SAM should be established as a new standard medium for a more promising in vitro adipogenic differentiation.

Association of the PPAR-gamma Gene with Altered Glucose Levels and Psychosis Profile in Schizophrenia Patients Exposed to Antipsychotics

OBJECTIVE: Metabolic abnormalities, e.g., diabetes, are common among schizophrenia patients. Peroxisome proliferator activated receptor-gamma (PPAR-gamma) regulates glucose/lipid metabolisms, and schizophrenia like syndrome may be induced by actions involving retinoid X receptor-alpha/PPAR-gamma heterodimers. We examined a possible role of the PPAR-gamma gene in metabolic traits and psychosis profile in schizophrenia patients exposed to antipsychotics. METHODS: Single nucleotide polymorphisms (SNPs) of the PPAR-gamma gene and a serial of metabolic traits were determined in 394 schizophrenia patients, among which 372 were rated with Positive and Negative Syndrome Scale (PANSS). RESULTS: SNP-10, -12, -18, -19, -20 and -26 were associated with glycated hemoglobin (HbA1c) whereas SNP-18, -19, -20 and -26 were associated with fasting plasma glucose (FPG). While SNP-23 was associated with triglycerides, no associations were identified between the other SNPs and lipids. Further haplotype analysis demonstrated an association between the PPAR-gamma gene and psychosis profile. CONCLUSION: Our study suggests a role of the PPAR-gamma gene in altered glucose levels and psychosis profile in schizophrenia patients exposed to antipsychotics. Although the Pro12Ala at exon B has been concerned an essential variant in the development of obesity, the lack of association of the variant with metabolic traits in this study should not be treated as impossibility or a proof of error because other factors, e.g., genes regulated by PPAR-gamma, may have complicated the development of metabolic abnormalities. Whether the PPAR-gamma gene modifies the risk of metabolic abnormalities or psychosis, or causes metabolic abnormalities that lead to psychosis, remains to be examined.

Peanut sprouts extract (Arachis hypogaea L.) has anti-obesity effects by controlling the protein expressions of PPARgamma and adiponectin of adipose tissue in rats fed high-fat diet

BACKGROUD/OBEJECTIVES: This study aims to find out the effects of peanut sprout extracts on weight controls and protein expressions of transcription factors related to adipocyte differentiation and adipocytokine in rats under high-fat diets. MATERIALS/METHODS: Four week-old Sparague-Dawley (SD) were assigned to 4 groups; normal-fat (NF) diets (7% fat diet), high-fat (HF) diets (20% fat diet), high fat diets with low peanut sprout extract (HF + PSEL) diet (20% fat and 0.025% peanut sprout extract), and high fat diets with high peanut sprout extract (HF + PSEH) diet (20% fat and 0.05% peanut sprout extract). Body weight changes, lipid profiles in adipose tissue, and the mRNA protein expressions, such as peroxisome proliferator-activated receptor gamma (PPARgamma), CCAAT element binding protein alpha (C/EBP alpha), leptin, and adiponectin, were determined. RESULTS: After 9 weeks of feeding, the HF + PSEH group had significantly less weight gains than the HF group (P < 0.05). However, the total dietary intakes or food efficiency ratios among groups were not significantly different. The weight of epididymal fat in HF + PSEH group, 3.61 +/- 0.5 g, or HF + PSEL group, 3.80 +/- 0.7 g, was significantly lower than the HF group, 4.39 +/- 0.4g, (P < 0.05). Total lipids and total cholesterol in adipose tissue were significantly decreased in HF + PSEH group compared to those in the HF group, respectively (P < 0.05). PSEH supplementation caused AST and ALT levels to decrease when it compared to HF group, but it was not statistically significant. The protein expression of PPARgamma in HF + PSEH group was significantly lower than the HF group (P < 0.05). Comparing with the HF group, the protein expression of adiponectin in HF + PSEH group was significantly increased (P < 0.05). The protein expressions of C/EBP alpha and leptin in HF + PSEH group were lower than the HF group, but it was not statistical significant. CONCLUSIONS: In conclusion, peanut sprout extract has anti-obesity effect by lowering the expressions of PPARgamma which regulates the expression of adiponectin.

Histopathological Evaluation of Heart Toxicity of a Novel Selective PPAR-gamma Agonists CKD-501 in db/db Mice

High risk of cardiovascular diseases caused by existing PPAR-gamma agonists such as rosiglitazone and pioglitazone has been recently reported. CKD-501 is a novel selective PPAR-gamma agonist as a potential target to reduce cardiovascular risk in non-insulin dependent diabetes mellitus (NIDDM). In this study, We investigated potential cardiotoxicity of CKD-501 and compared its toxicity with that of rosiglitazone or pioglitazone using db/db mice. After 12-week repeated administration of CKD-501 at doses of 3, 10 and 30 mg/kg/day or rosiglitazone at doses of 10 and 30 mg/kg/day or pioglitazone at doses of 200 and 540 mg/kg/day, animals were sacrificed for investigation of potential toxicities. Diameters of left ventricles and areas of cardiomyocytes were measured. And lipid accumulation and apoptosis in heart muscle were examined by oil red O staining and TUNEL staining, respectively. Diameters of left ventricles were significantly increased in high dose treatment group of pioglitazone compared to control (p CKD-501 > or = rosiglitazone. However, lipid accumulation and apoptotic changes in heart were not observed in all dosing groups. Taken together, the myocardial cell hypertrophy of CKD-501 are relatively lower than that of pioglitazone and similar to rosiglitazone. And it is suggested that the myocardial cell hypertrophy of CKD-501 are less adverse in clinical use for the management of the NIDDM.

Modulation of the Transcriptional Activity of Peroxisome Proliferator-Activated Receptor Gamma by Protein-Protein Interactions and Post-Translational Modifications

Peroxisome proliferator-activated receptor gamma (PPARgamma) belongs to a nuclear receptor superfamily; members of which play key roles in the control of body metabolism principally by acting on adipose tissue. Ligands of PPARgamma, such as thiazolidinediones, are widely used in the treatment of metabolic syndromes and type 2 diabetes mellitus (T2DM). Although these drugs have potential benefits in the treatment of T2DM, they also cause unwanted side effects. Thus, understanding the molecular mechanisms governing the transcriptional activity of PPARgamma is of prime importance in the development of new selective drugs or drugs with fewer side effects. Recent advancements in molecular biology have made it possible to obtain a deeper understanding of the role of PPARgamma in body homeostasis. The transcriptional activity of PPARgamma is subject to regulation either by interacting proteins or by modification of the protein itself. New interacting partners of PPARgamma with new functions are being unveiled. In addition, post-translational modification by various cellular signals contributes to fine-tuning of the transcriptional activities of PPARgamma. In this review, we will summarize recent advancements in our understanding of the post-translational modifications of, and proteins interacting with, PPARgamma, both of which affect its transcriptional activities in relation to adipogenesis.

Frequency of RAS Mutations and PAX8/PPARgamma Rearrangement in Follicular Thyroid Tumors in Korea

BACKGROUND: Follicular thyroid tumors harbor several genetic alterations such as RAS mutations and PAX8/PPARgamma rearrangement. The aims of our study were to investigate the prevalence of RAS mutations and PAX8/PPARgamma rearrangement in follicular thyroid tumors and to correlate RAS mutations and/or PAX8/PPARgamma rearrangement with clinicopathologic features in Korean patients with follicular thyroid carcinomas. METHODS: RAS mutations were investigated by polymerase chain reaction and DNA sequencing in surgical specimens of 37 follicular thyroid carcinomas (FTCs) and 16 follicular thyroid adenomas (FTAs). PAX8/PPARgamma rearrangement was analyzed by fluorescent in situ hybridization in surgical specimens of 31 FTCs and 13 FTAs. RESULTS: RAS mutations were detected in 30% (11 of 37) of FTCs and 19% (three of 16) of FTAs. Three of 11 FTC patients with RAS mutations died of thyroid cancer, but none of the 26 FTC patients without RAS mutations. PAX8/PPARgamma rearrangement was found in 10% (three of 31) of FTCs, but in none of the 13 FTAs. All three FTC patients with PAX8/PPARgamma rearrangement remained in complete remission during follow-up. There were no FTC patients with both RAS mutations and PAX8/PPARgamma rearrangement. CONCLUSION: The prevalence of RAS mutations in our series of follicular tumors was similar to previous studies. The frequency of PAX8/PPARgamma rearrangements in our group of FTC was lower than previous western reports, but higher than Japanese reports. RAS mutations may be associated with hematogeneous metastasis and poor survival while PAX8/PPARgamma rearrangement may be related to more favorable prognosis in Korean patients with FTCs.

Antidiabetic Effects of Corni Fructus Extract in Streptozotocin-Induced Diabetic Rats

PURPOSE: Diabetes is the leading cause of end-stage renal failure. The present study was undertaken to characterize the effects of Corni Fructus on diabetic nephropathy in streptozotocin-induced diabetic rats and their mechanisms. MATERIALS AND METHODS: Streptozotocin-diabetic rats were orally administrated with Corni Fructus at a dose of 100, 200 or 400 mg/kg body mass for 40 days. RESULTS: Corni Fructus-treated diabetic rats showed significant decreases of blood glucose, urinary protein levels and water consumption. Corni Fructus also reduced serum total cholesterol, total triglyceride and low-density lipoprotein cholesterol levels, and showed a tendency of enhancing high-density lipoprotein cholesterol level. Levels of serum albumin and creatinine in diabetic rats were also significantly reduced by Corni Fructus administration at a dose of 200 and 400 mg/kg body mass compared with non-treated diabetic rats. Corni Fructus increased catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidose (GSH-px) activities in the kidneys of diabetic rats. Furthermore, Corni Fructus treatment enhanced renal peroxisome proliferator-activated receptor-gamma (PPARgamma) expression in diabetic rats. CONCLUSION: These results demonstrated that Corni Fructus may have the potential to protect the animals from diabetic nephropathy by amelioration of oxidative stress and stimulation of PPARgamma expression.

The Effects of Combined Treatment with an HMG-CoA Reductase Inhibitor and PPARgamma Agonist on the Activation of Rat Pancreatic Stellate Cells

BACKGROUND/AIMS: Hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors (statins) and peroxisome proliferator-activated receptor gamma (PPARgamma) ligands can modulate cellular differentiation, proliferation, and apoptosis through various pathways. It has been shown that HMG-CoA reductase inhibitors and PPARgamma agonists separately inhibit pancreatic stellate cell (PaSC) activation. We studied the effects of a combination of both types of drugs on activated PaSCs via platelet-derived growth factor (PDGF), which has not previously been reported. The present study was performed to elucidate the underlying mechanisms of these effects by focusing on the impact of the signaling associated with cell-cycle progression. METHODS: Primary cultures of rat PaSCs were exposed to simvastatin and troglitazone. Proliferation was quantified using the BrdU method, and cell-cycle analysis was performed using a fluorescent activated cell sorter. The protein expression levels of smooth muscle actin (SMA), extracellular signal-regulated kinase (ERK), and a cell cycle machinery protein (p27Kip1) were investigated using Western blot analysis. RESULTS: Simvastatin reversed the effects of PDGF on cell proliferation in a dose-dependent manner. The combination of a low concentration of simvastatin (1 mM) and troglitazone (10 mM) synergistically reversed the effects of PDGF on cell proliferation but had no effect on cell viability. The expression of a-SMA was markedly attenuated by combining the two drugs, which blocked the cell cycle beyond the G0/G1 phase by reducing the levels of phosphorylated ERK and reversed the expression of p27Kip1 interrupted by PDGF. CONCLUSIONS: Simvastatin and troglitazone synergistically inhibited cell proliferation in activated PaSCs by blocking the cell cycle beyond the G0/G1 phase. This inhibition was due to the synergistic modulation of the ERK pathway and the cell cycle machinery protein p27Kip1.

Sorghum extract exerts an anti-diabetic effect by improving insulin sensitivity via PPAR-gamma in mice fed a high-fat diet

This study investigated the hypothesis that a sorghum extract exerts anti-diabetic effects through a mechanism that improves insulin sensitivity via peroxisome proliferator-activated receptor gamma (PPAR-gamma) from adipose tissue. Seven C57BL/6 mice were fed an AIN-93M diet with fat consisting of 10% of total energy intake (LF) for 14 weeks, and 21 mice were fed a high-fat AIN diet with 60% of calories derived from fat (HF). From week 8, the HF diet-fed mice were orally administered either saline (HF group), 0.5% (0.5% SE group), or 1% sorghum extract (1% SE group) for 6 weeks (n = 7/group). Perirenal fat content was significantly lower in the 0.5% SE and 1% SE groups than that in the HF mice. Levels of total and low-density lipoprotein cholesterol, triglycerides, glucose, and the area under the curve for glucose were significantly lower in mice administered 0.5% SE and 1% SE than those in HF mice. Serum insulin level was significantly lower in mice administered 1% SE than that in HF mice or those given 0.5% SE. PPAR-gamma expression was significantly higher, whereas the expression of tumor necrosis factor-alpha was significantly lower in mice given 1% SE compared to those in the HF mice. Adiponectin expression was also significantly higher in mice given 0.5% SE and 1% SE than that in the HF mice. These results suggest that the hypoglycemic effect of SE may be related with the regulation of PPAR-gamma-mediated metabolism in this mouse model.

Treatment of mild to moderate Graves' ophthalmopathy with sodium diclofenac: a pilot study / Tratamento da oftalmopatia de Graves leve a moderada com diclofenato de sódio: um estudo piloto

OBJECTIVE: To report the use of sodium diclofenac, an antagonist of PPAR-gamma and cyclooxigenase-2 (COX-2) inhibitor in the treatment of mild to moderate Graves' ophthalmopathy. SUBJECTS AND METHODS: Thirteen patients with clinical activity score (CAS) 2 to 7 were treated during a period ranging from 3 to 12 months (mean 7.8 ± 3.4) with oral sodium diclofenac, 50 mg every 12 hours. RESULTS: Extra-ocular muscle restriction and CAS improved significantly, p = 0.003 and = 0.004, respectively. Ocular pain and diplopia disappeared, except for one patient who reported improvement of these symptoms. No recurrence was found after interruption of treatment. CONCLUSIONS: Treatment of moderate Graves' ophthalmopathy with oral sodium diclofenac is a good, safe and less expensive therapeutic option. Like others new treatment trials, findings must be confirmed in a greater number of patients in a controlled study.

OBJETIVO: Relatar o uso do diclofenato de sódio, um antagonista do PPAR-gama e inibidor da ciclooxigenase-2 (COX-2) no tratamento da leve a moderada oftalmopatia de Graves. SUJEITOS E MÉTODOS: Treze pacientes com CAS (clinical activity score) 2 a 7 foram tratados durante um período de 3 a 12 meses (média 7,6 ± 3,4) com diclofenaco de sódio por via oral na dose de 50 mg a cada 12 horas. RESULTADOS: A restrição da musculatura extraocular e o índice CAS melhoraram de modo significativo, respectivamente p = 0,003 e p = 0,004. A dor ocular e a diplopia desapareceram, com exceção de um paciente que referiu melhora desses sintomas. Não houve recidiva após a interrupção do tratamento. CONCLUSÕES: O tratamento da oftalmopatia de Graves de média gravidade com diclofenaco de sódio por via oral é uma opção boa, segura e de baixo custo. Como outros novos tratamentos, ele deverá ser confirmado em um maior número de pacientes em estudos controlados.

HO-1 Induced by Cilostazol Protects Against TNF-alpha-associated Cytotoxicity via a PPAR-gamma-dependent Pathway in Human Endothelial Cells

A large body of evidence has indicated that induction of endogenous antioxidative proteins seems to be a reasonable strategy for delaying the progression of cell injury. In our previous study, cilostazol was found to increase the expression of the antioxidant enzyme heme oxygenase-1 (HO-1) in synovial cells. Thus, the present study was undertaken to examine whether cilostazol is able to counteract tumor necrosis factor-alpha (TNF-alpha)-induced cell death in endothelial cells via the induction of HO-1 expression. We exposed human umbilical vein endothelial cells (HUVECs) to TNF-alpha (50 ng/ml), with or without cilostazol (10 microM). Pretreatment with cilostazol markedly reduced TNF-alpha-induced viability loss in the HUVECs, which was reversed by zinc protoporphyrine IX (ZnPP), an inhibitor of HO-1. Moreover, cilostazol increased HO-1 protein and mRNA expression. Cilostazol-induced HO-1 induction was markedly attenuated not only by ZnPP but also by copper-protoporphyrin IX (CuPP). In an assay measuring peroxisome proliferator-activated receptor-gamma (PPAR-gamma) transcription activity, cilostazol directly increased PPAR-gamma transcriptional activity which was completely abolished by HO-1 inhibitor. Furthermore, increased PPAR-gamma activity by cilostazol and rosiglitazone was completely abolished in cells transfected with HO-1 siRNA. Taken together, these results indicate that cilostazol up-regulates HO-1 and protects cells against TNF-alpha-induced endothelial cytotoxicity via a PPAR-gamma-dependent pathway.

Alteração do tecido adiposo e fígado em modelo experimental de síndrome metabólica: ação de agonista PPAR-gama e bloqueador de receptor AT1 da angiotensina 2 / Change of adipose tissue and liver in an experimental of metabolic syndrome: the action of PPAR-gamma and AT1 receptor block angiotensin 2

Este trabalho teve como objetivo investigar os efeitos da telmisartana (agonista PPAR-gama parcial), losartana (puro bloqueador do receptor AT1 da angiotensina II) e rosiglitazona (agonista PPAR-gama) em modelo experimental de síndrome metabólica. Os alvos do estudo foram a pressão arterial, metabolismo de carboidratos, resistência insulínica, inflamação, tecido adiposo e fígado. Camundongos C57BL/6 (a partir de 3 meses de idade) foram alimentados com dieta padrão (SC, n = 10) ou dieta hiperlipídica rica em sal (HFHS, n = 40) por 12 semanas. Após esse tempo, os animais do grupo HFHS foram subdivididos em 4 grupos (n = 10): HFHS (sem tratamento), ROSI (HFHS tratado com rosiglitazona), TELM (HFHS tratado com telmisartana) e LOS (HFHS tratado com losartana) por 5 semanas. O grupo HFHS apresentou um significante ganho de peso e aumento da pressão arterial sistólica, hiperinsulinemia com resistência insulínica, hiperleptinemia, hipertrofia de adipócitos bem como um quadro de esteatose hepática e níveis aumentados da citocina inflamatória interleucina-6 (IL-6). Os animais tratados com telmisartana chegou ao final do experimento com massa corporal similar ao grupo SC, com reversão do quadro de resistência insulínica, com pressão arterial normal, adipócitos de tamanho normal e sem apresentar esteatose hepática. Além disso, o tratamento com telmisartana aumentou a expressão de PPARγ e adiponectina no tecido adiposo epididimal. A expressão da proteína desacopladora-1 (UCP-1) no tecido adiposo branco (TAB) também foi aumentada. O tratamento com losartana diminuiu a pressão arterial para valores normais, porém com menores efeitos nos parâmetros metabólicos dos animais. O presente modelo experimental de ganho de peso e hipertensão induzidos por dieta mimetiza a síndrome metabólica humana. Neste modelo, a telmisartana aumentou a expressão de UCP-1 no TAB, preveniu o ganho de peso e melhorou a sensibilidade à insulina e a esteatose hepática dos camundongos C57BL/6...

The study aimed to investigate the effects of telmisartan (a partial PPAR gamma agonist), losartan (a pure angiotensin II receptor blocker) and rosiglitazone (PPAR gamma agonist) in a mice model of metabolic syndrome (MetS). The targets of this study were blood pressure (BP), carbohydrate metabolism, insulin resistance, inflammation, white adipose tissue (WAT) and liver. Male C57BL/6 mice were studied over 17 weeks after being separated into two major groups according to diet: standard chow (SC, 10% fat, n = 10) or high-fat high-salt chow (HFHS, 60% fat, 7% salt, n = 40). In the last 5 weeks of the experiment, the HFHS group was divided into four groups (n = 10): untreated HFHS, ROSI (HFHS plus rosiglitazone), TELM (HFHS plus telmisartan), and LOS (HFHS plus losartan). The HFHS group had significantly greater body mass and BP, in addition to hyperinsulinemia with insulin resistance, hyperleptinemia, adipocyte hypertrophy and hepatic steatosis as well as increased inflammatory cytokine levels. Animals treated with telmisartan had body weights similar to the SC group, in addition to reversed insulin resistance, reduced hypertension, reduced adipocyte hypertrophy, ameliorates hepatic steatosis and decreased IL-6. Telmisartan increased PPARγ and adiponectin expression in white adipose tissue. Interestingly, the expression of UCP-1 in white adipose tissue was also increased by treatment with telmisartan. Losartan decreased BP but had smaller effects on metabolic parameters. The present model of diet-induced weight gain and hypertension in mice mimics human features of MetS. In this model, telmisartan enhances UCP-1 expression in WAT, prevented weight gain and ameliorates insulin sensitivity and hepatic steatosis in C57Bl/6 mice, probably due to PPAR gamma activation.

Duration and Magnitude of Extracellular Signal-Regulated Protein Kinase Phosphorylation Determine Adipogenesis or Osteogenesis in Human Bone Marrow-Derived Stem Cells

PURPOSE: Imbalances between osteogenic and adipogenic differentiation leads to diseases such as osteoporosis. The aim of our study was to demonstrate the differences in extracellular signal-regulated kinase (ERK) phosphorylation during both adipogenesis and osteogenesis of human bone marrow-derived stem cells (BMSCs). MATERIALS AND METHODS: Using troglitazone, GW9662 and U0126, we investigated their role in hBMSC differentiation to adipogenic and osteogenic fates. RESULTS: ERK1/2 inhibition by U0126 suppressed proliferator-activated receptor (PPAR)gamma expression and lipid accumulation, while it decreased the mRNA expression of adipogenic genes (lipoprotein lipase, PPARgamma, and adipocyte protein) and osteogenic genes (type I collagen and osteopontin). ERK phosphorylation was transient and decreased during adipogenesis, whereas it occurred steadily during osteogenesis. Troglitazone, a PPARgamma agonist, induced adipogenesis by inhibiting ERK phosphorylation even in an osteogenic medium, suggesting that ERK signaling needs to be shut off in order to proceed with adipose cell commitment. Cell proliferation was greatly increased in osteogenesis but was not changed during adipogenesis, indicating that ERK might play different roles in cellular proliferation and differentiation between the two committed cell types. CONCLUSION: The duration and magnitude of ERK activation might be a crucial factor for the balance between adipogenesis and osteogenesis in human bone marrow-derived stem cells.

Duration and Magnitude of Extracellular Signal-Regulated Protein Kinase Phosphorylation Determine Adipogenesis or Osteogenesis in Human Bone Marrow-Derived Stem Cells

PURPOSE: Imbalances between osteogenic and adipogenic differentiation leads to diseases such as osteoporosis. The aim of our study was to demonstrate the differences in extracellular signal-regulated kinase (ERK) phosphorylation during both adipogenesis and osteogenesis of human bone marrow-derived stem cells (BMSCs). MATERIALS AND METHODS: Using troglitazone, GW9662 and U0126, we investigated their role in hBMSC differentiation to adipogenic and osteogenic fates. RESULTS: ERK1/2 inhibition by U0126 suppressed proliferator-activated receptor (PPAR)gamma expression and lipid accumulation, while it decreased the mRNA expression of adipogenic genes (lipoprotein lipase, PPARgamma, and adipocyte protein) and osteogenic genes (type I collagen and osteopontin). ERK phosphorylation was transient and decreased during adipogenesis, whereas it occurred steadily during osteogenesis. Troglitazone, a PPARgamma agonist, induced adipogenesis by inhibiting ERK phosphorylation even in an osteogenic medium, suggesting that ERK signaling needs to be shut off in order to proceed with adipose cell commitment. Cell proliferation was greatly increased in osteogenesis but was not changed during adipogenesis, indicating that ERK might play different roles in cellular proliferation and differentiation between the two committed cell types. CONCLUSION: The duration and magnitude of ERK activation might be a crucial factor for the balance between adipogenesis and osteogenesis in human bone marrow-derived stem cells.

Over-expression of PTEN Involved in Troglitazone-induced Apoptosis in Human Osteosarcoma Cells / 대한골관절종양학회지

PURPOSE: We investigated the effects of phosphatase and tensin homologue deleted on chromosome 10 gene phosphatase and tensin homologue deleted on chromosome 10 gene (PTEN) expression on the cell proliferation and on the responsiveness of troglitazone in osteosarcoma cells. MATERIALS AND METHODS: Western blotting alnalysis was performed to detect the expression of PTEN in U-2OS cells treated with troglitazone. WST (water-soluble tetrazolium) assay was used to evaluate cell proliferation. Flow cytometry was used to determine cell apoptosis. Further, transfection of wild-type PTEN plasmid DNA was used to upregulate PTEN expression. RESULTS: Troglitazone treatment induced growth inhibition of U2-OS cells in a dose- and time-dependent manner. Troglitazone increased the expression of PTEN in a dose-dependent manner. PTEN upregulation induced by troglitazone treatment resulted in cell growth inhibition and apoptosis in U-2OS cells. PTEN over-expression by plasmid transfection enhanced these effects of troglitazone. Moreover, no changes were observed in the mutant type-PTEN group. CONCLUSION: Upregulation of PTEN is involved in the inhibition of cell growth and induction of cell apoptosis by troglitazone. Further, PTEN over-expression can cause cell growth inhibition in osteosarcoma cells and these cell growth inhibitions could be enhance by troglitazone treatment.