Inhibition of proliferation and transforming growth factor β3 protein expression by peroxisome proliferators-activated receptor γ ligands in human uterine leiomyoma cells

Background Rosiglitazone is known as the most potent and specific peroxisome proliferators-activated receptor γ （PPAR-γ） ligand. It has potentially far-reaching effects on pathophysiological processes, from cancer to atherosclerosis and diabetes. However, it is not clear whether rosiglitazone affects the protein expression of transforming growth factor β3 （TGF-β3） and the cell proliferation in human uterine leiomyoma cells in vitro.Methods Human uterine leiomyoma tissues were dissected and cultured. Cells were divided into 5 groups： one control group and other four groups with different concentrations of rosiglitazone （10^-7, 10^-8, 10^-9 and 10^-10 mol/L）. Cells were cultured for 72 hours in serum-free Dulbecco＇s modified Eagle＇s medium. MTT reduction assay was used to detect the cell proliferation. Reverse transcription polymerase chain reaction （RT-PCR） was used to detect the mRNA expression of PPAR-γ and TGF-β3. Immunofluorescence staining was used to detect the expressions of PPAR-γ and TGF-β3 proteins. Results MTT reduction assay indicated that the treatment with rosiglitazone （from 10^-7 to 10^-9 mol/L） resulted in an inhibition of the cell growths after 72 hours （P〈0.01）. RT-PCR analysis revealed that 10^-7 mol/L rosiglitazone significantly affected the gene expression at 72-hour： PPAR-γ mRNA expression was up-regulated and TGF-β3 mRNA was down-regulated and rosiglitazone at the concentration of 10-7 mol/L affected these most effectively （P〈0.01）. Immunofluorescence staining demonstrated that treatment with 10^-7 mol/L rosiglitazone resulted in the significant changes of PPAR-γ and TGF-β3 protein expressions compared with the other treatment groups and the control group at 72-hour （P〈0.01）. All the effects of rosiglitazone on uterine leiomyoma cells were dose- and time-dependent in vitro. Conclusions The present study demonstrates that the PPAR-γ activator, rosiglitazone, inhibits the cell proliferation partly through the regulations of PPAR-γ and TGF-β3 expressions. The cross-talk between the signal pathways of PPAR-γ and TGF-β3 may be involved in the process.

Rhinacanthus nasutus leaf improves metabolic abnormalities in high-fat diet-induced obese mice

Objective:To investigate the effect of Rhinacanthus nasutus(R.nasutus) leaf extract on impaired glucose and lipid metabolism in obese ICR mice.Methods:Obesity was induced in the male ICR mice by feeding them a high-fat diet(60 kcal%fat) for 12 weeks.After the first six weeks of the diet,the obese mice were administered with the water extract of R.nasutus leaves at 250 and 500 mg/kg per day for the next six weeks.Subsequently,the blood glucose,lipid profiles,insulin,leptin,and adiponectin levels were measured.The liver and adipose tissues were excised for histopathological examination and protein expression study.Results:After six weeks of the treatment,R.nasutus extract(at 250 and 500 mg/kg per day) was found to reduce the elevated blood glucose level,improve the insulin sensitivity,decrease the serum leptin,and increase the serum adiponectin levels.The obese mice treated with R.nasutus were found to have a reduction in the increased lipid concentrations in their serum and liver tissues.Moreover,treatment with R.nasutus reduced the fat accumulation in the liver and the large adipocyte size in the fat tissues.Interestingly,the administration with R.nasutus extract was marked by an increase in the hepatic peroxisome proliferators-activated receptor alpha,fat cell adiponectin,and glucose transporter 4 proteins.Conclusions:To the best of our knowledge,the present study is the first report on the impact of R.nasutus extract in improving the impaired glucose and lipid metabolism in high-fat diet-induced obesity in mice via stimulating the insulin sensitivity in the liver and adipose tissues.

Tagging single nucleotide polymorphisms in the PPAR-γ and RXR-α gene and type 2 diabetes risk:a case-control study of a Chinese Han population

Peroxisome proliferator-activated receptor （PPAR-γ）,which is mainly involved in adipocyte differentiation, has been suggested to play an important role in the pathogenesis of insulin resistance and atherosclerosis. We investigated the frequencies of two common tagging polymorphisms of the PPAR-γ gene and two of PPAR-α with minor allele frequency （MAF）≥ 0.05 in the Chinese Han population and analyzed the correlation between the different genotypes and the risk of type 2 diabetes mellitus （T2DM）. TaqMan assay was performed to test the genotypes in T2DM patients （n = 1,105） and normal controls （n = 1,107）. Serum adiponectin concentration was measured by ELISA kit. The variant genotypes rs17817276GG, rs3856806CT and rs3856806CT/TT of PPAR-γ were associated with T2DM, P = 0.023,0.037 and 0.018, respectively. Furthermore, the prevalence of haplotype GT in PPAR-γ was less frequent in the case subjects （0.3%） than in the controls （1.9%） [P 0.001,OR（95%CI）=0.13 （0.06-0.31）]. Patients with genotype TT of rs3856806 had a higher serum level of adiponectin than those with the genotype CC and CT （P = 0.031 and 0.038, respectively）. There was no statistically significant difference between patients and controls in genotype distribution of rs6537944 and rs1045570 of the RXR-α gene. The present study suggests that the variant genotypes in the PPAR-γ gene could decrease the risk for the development of T2DM in the Chinese Han population.

Telmisartan but not Valsartan Inhibits TGF-β-mediated Accumulation of Extracelluar Matrix via Activation of PPARγ

Glomerulosclerosis, defined as phenotype transition of mesangial cell and deposition of extracelluar matrix, remains a chronic disease with excessive morbidity and mortality. The molecular mechanism underlying the suppression of mesangial cell activation is not fully understood. Since activation of peroxisome proliferators-activated receptor γ （PPARγ） has been proposed to decrease the effects of transforming growth factor-β （TGF-β） on glomerulosclerosis, we examined here whether and how telmisartan, an angiotensin Ⅱ type 1 receptor blocker with PPARγ-modulating activity, inhibited TGF-β-induced glomerulosclerosis in rat glomerular mesangial cells. Protein levels of PPARγ were detected by Western blot. Activation of PPARγ response element （PPRE） was analyzed by luciferase assays. Deposition of extracelluar matrix was tested by confocol laser scanning. The results showed that telmisartan, but not valsartan, another angiotensin Ⅱ type 1 receptor blocker, up-regulated PPARγ protein levels in a dose-dependent manner （P〈0.05）. Activation of PPRE, represented by luciferase activity, was also increased with higher concentration of telmisartan in a dose-dependent manner （P〈0.05）. Furthermore, telmisartan inhibited TGF-β-induced α-smooth muscle actin expression and collagen IV secretion in mesangial cells. GW9662, an inhibitor of PPAR-γ, blocked the inhibitory effects of telmisartan on TGF-β-induced glomerulosclerosis in mesangial cells. Our study indicates a benefit of telmisartan as a PPARγ agonist against TGF-β-induced mesangial cells activation in renal glomerulus. It may provide possibility that telmisartan works as a potential agent against diabetic nephropathy and hypertensive renal disease.

Effects of clenbuterol exposure on PPARγ expression in adipocytes of rats

Objective To investigate effects of clenbuterol （CLB） on the peroxisome proliferators- activated receptor γ （PPARγ） expression in adipose tissues of rats. Methods Twenty adult female Sprague-Dawley rats were randomly divided into 4 groups （5 rats per group）. CLB solved in normal saline solution was given at the dose of 0 mg/kg body weight （bw） （group A, as the control）, 0.4 mg/kg bw （group B, low-dose group）, 2.0 mg/kg bw （group C, mid-dose group）, and 18.5 mg/kg bw （group D, high-dose group）for 14 d by gavage consecutively, respectively. Methods of immunohistochemistry, quantitative Real-time PCR and Western blotting were performed to detect expression of PPARγ in the adipose tissue samples. Results PPARγ-positive immunostaining was strong in the controls and weak in the experimental groups. There was no difference on PPARγmRNA and protein between the low-dose group and the control （P〉0.05）. With the increase of CLB doses, expression levels of PPARγmRNA and protein were significantly lower in mid- or high-dose group than those in the control （19〈0.01）. Conclusions The PPARγ expression in adipose tissues of rats could be down-regulated after CLB exposure, and the decrease became more severe with the increasing doses.

过氧化物酶体增殖物激活受体γ与调节性T细胞

调节性T细胞（regulatory T cells，Tregs）已成为变应性疾病、自身免疫性疾病、移植耐受和肿瘤免疫等领域的研究热点。近年来研究发现过氧化物酶体增殖物激活受体（peroxisome proliferators—actived receptor，PPAR）γ配体可以通过PPARγ-依赖和／或PPARγ-非依赖途径诱导Tregs的转化和扩增，从而在变应性疾病和自身免疫性疾病的免疫调节中发挥重要作用。本文就PPARγ及其配体与Tregs转化和扩增的作用机制做一综述。