DRF 2655: A Unique Molecule that Reduces Body Weight and Ameliorates Metabolic Abnormalities

Objective: Preclinical evaluation of DRF 2655, a peroxisome proliferator‐activated receptor alpha (PPARα) and PPARγ agonist, as a body‐weight lowering, hypolipidemic and euglycemic agent. Research Methods and Procedures: DRF 2655 was studied in different genetic, normal, and hyperlipidemic animal models. HEK 293 cells were used to conduct the reporter‐based transactivation of PPARα and PPARγ. To understand the biochemical mechanism of lipid‐, body‐weight‐, and glucose‐lowering effects, activities of key β‐oxidation and lipid catabolism enzymes and gluconeogenic enzymes were studied in db/db mice treated with DRF 2655. 3T3L1 cells were used for adipogenesis study, and HepG2 cells were used to study the effect of DRF 2655 on total cholesterol and triglyceride synthesis using [¹⁴C]acetate and [³H]glycerol. Results: DRF 2655 showed concentration‐dependent transactivation of PPARα and PPARγ. In the 3T3L1 cell‐differentiation study, DRF 2655 and rosiglitazone showed 369% and 471% increases, respectively, in triglyceride accumulation. DRF 2655 showed body‐weight lowering and euglycemic and hypolipidemic effects in various animal models. db/db mice treated with DRF 2655 showed 5‐ and 3.6‐fold inhibition in phosphoenolpyruvate carboxykinase and glucose 6‐phosphatase activity and 651% and 77% increases in the β‐oxidation enzymes carnitine palmitoyltransferase and carnitine acetyltransferase, respectively. HepG2 cells treated with DRF 2655 showed significant reduction in lipid synthesis. Discussion: DRF 2655 showed excellent euglycemic and hypolipidemic activities in different animal models. An exciting finding is its body‐weight lowering effect in these models, which might be mediated by the induction of target enzymes involved in hepatic lipid catabolism through PPARα activation.     

寡核苷酸芯片技术用于检测过氧化物酶体活化物激活受体基因多态性

 通过寡核苷酸芯片技术检测PPARα基因Leu162Val、Val227Ala多态性和PPARγ Pro12Ala的基因多态性,建立一种快速、简便、准确的方法,为研究非酒精性脂肪性肝病的发病机制、临床诊断和治疗提供依据.收集人体外周血标本,提取DNA进行PCR扩增,设计相应的探针和引物,制备检测芯片,PCR产物与芯片杂交后,扫描芯片并分析结果.PCR产物进行测序验证.寡核苷酸芯片技术检测PPARα基因Leu162Val、Val227Ala多态性和PPARγ Pro12Ala基因多态性结果与测序结果一致.寡核苷酸芯片技术检测非酒精性脂肪性肝病(NAFLD)密切相关的PPAR基因多态性快速、准确,值得临床推广和应用.     

Expression of peroxisome proliferator-activated receptors alpha and gamma in differentiating human colon carcinoma Caco-2 cells

The expression of peroxisome proliferator-activated receptors alpha (PPARalpha) and gamma (PPARgamma) was studied in the human adenocarcinoma Caco-2 cells induced to differentiate by long term culture (15 days). The differentiation of Caco-2 cells was attested by increases in the activities of sucrase-isomaltase and alkaline phosphatase (two brush border enzymes), fatty acyl-CoA oxidase (AOX) and catalase (two peroxisomal enzymes), by an elevation in the protein levels of villin (a brush border molecular marker), AOX, peroxisomal bifunctional enzyme (PBE), catalase and peroxisomal membrane protein of 70 kDa (PMP70). and by the appearance of peroxisomes. The expression of PPARalpha and PPARgamma was investigated by Western blotting, immunocytochemistry, Northern blotting and S1 nuclease protection assay during the differentiation of Caco-2 cells. The protein levels of PPARalpha, PPARgamma, and PPARgamma2 increased gradually during the time-course of Caco-2 cell differentiation. Immunocytochemistry revealed that PPARalpha and gamma were localized in cell nuclei. The PPARgamma1 protein was encoded by PPARgamma3 mRNA because no signal was obtained for PPARgamma1 mRNA using a specific probe in S1 nuclease protection assay. The amount of PPARgamma3 mRNA increased concomitantly to the resulting PPARgamma1 protein. On the other hand, the mRNA of PPARalpha and PPARgamma2 were not significantly changed, suggesting that the increase in their respective protein was due to an elevation of the translational rate. The role played by the PPAR subtypes in Caco-2 cell differentiation is discussed.     

Metabolites related to gut bacterial metabolism,peroxisome proliferator‐activated receptor‐alpha activation,and insulin sensitivity are associated with physical function in functionally‐limited older adults

Identification of mechanisms underlying physical function will be important for addressing the growing challenge that health care will face with physical disablement in the expanding aging population. Therefore, the goals of the current study were to use metabolic profiling to provide insight into biologic mechanisms that may underlie physical function by examining the association between baseline and the 6‐month change in serum mass spectrometry‐obtained amino acids, fatty acids, and acylcarnitines with baseline and the 6‐month change in muscle strength (leg press one repetition maximum divided by total lean mass, LP/Lean), lower extremity function [short physical performance battery (SPPB)], and mobility (400 m gait speed, 400‐m), in response to 6 months of a combined resistance exercise and nutritional supplementation (whey protein or placebo) intervention in functionally‐limited older adults (SPPB ≤ 10; 70–85 years, N = 73). Metabolites related to gut bacterial metabolism (cinnamoylglycine, phenol sulfate, p‐cresol sulfate, 3‐indoxyl sulfate, serotonin, N‐methylproline, hydrocinnamate, dimethylglycine, trans‐urocanate, valerate) that are altered in response to peroxisome proliferator‐activated receptor‐alpha (PPAR‐α) activation (α‐hydroxyisocaproate, α‐hydroxyisovalerate, 2‐hydroxy‐3‐methylvalerate, indolelactate, serotonin, 2‐hydroxypalmitate, glutarylcarnitine, isobutyrylcarnitine, cinnamoylglycine) and that are related to insulin sensitivity (monounsaturated fatty acids: 5‐dodecenoate, myristoleate, palmitoleate; γ‐glutamylamino acids: γ‐glutamylglutamine, γ‐glutamylalanine, γ‐glutamylmethionine, γ‐glutamyltyrosine; branched‐chain amino acids: leucine, isoleucine, valine) were associated with function at baseline, with the 6‐month change in function or were identified in backward elimination regression predictive models. Collectively, these data suggest that gut microbial metabolism, PPAR‐α activation, and insulin sensitivity may be involved in mechanisms that underlie physical function in functionally‐limited older adults.     

Ethanol specifically decreases peroxisome proliferator activated receptor beta in B12 oligodendrocyte-like cells

Peroxisome proliferator activated receptors (PPARs) are nuclear receptors that control important genes involved in lipid metabolism. Their role in nerve cells is uncertain, although anomalous myelination of the corpus callosum has been described in the PPARbeta-null mouse, and abnormalities of this tissue have been documented in fetal alcohol syndrome in humans. We report here that ethanol treatment of B12 oligodendrocyte-like cells induces a concentration- and time-dependent decrease in the mRNA and protein levels of PPARbeta, with no effect on PPARalpha or PPARgamma. The effect on PPARbeta is seen as an increase in mRNA degradation, as assessed by run-off assays, due to a significant decrease in PPARbeta mRNA half-life, with no observed changes in intracellular localization. Our results suggest a possible link between PPARbeta function and ethanol-induced abnormal myelination in oligodendrocytes.     

Heterogeneous effect of peroxisome proliferator-activated receptor gamma2 Ala12 variant on type 2 diabetes risk

Conflicting results have been reported regarding whether the PPARgamma2 Pro12Ala polymorphism plays a role in the risk of type 2 diabetes (T2D), suggesting genetic heterogeneity. To investigate this issue, a meta-analysis of 41 published and 2 unpublished studies (a total of 42,910 subjects) was conducted. Ala12 carriers had a 19% T2D risk reduction, but this association was highly heterogeneous (p = 0.005). A great proportion (48%) of heterogeneity was explained by the controls' BMI, with risk reduction being greater when BMI was lower. Risk reduction of Ala12 carriers in Asia (35%) was higher than in Europe (15%, p = 0.02) and tended to be higher than in North America (18%, p = 0.10). Difference between Asians and Europeans was no longer significant (p = 0.15) after adjusting for the controls' BMI. Studies from Europe were still heterogeneous (p = 0.02) with risk reduction in Ala12 carriers being progressively smaller (test for trend in the odds ratios, p = 0.02) from Northern (26% reduction, p < 0.0001) to Central (10%, p = 0.04) and Southern (0%, p = 0.94) Europe. In conclusion, in our meta-analysis, the reduced risk of T2D in Ala12 carriers is not homogeneous. It is greater in Asia than in Europe and, among Europeans, it is higher in Northern Europe, barely significant in Central Europe, and nonexistent in Southern Europe.     

AMPK/SIRT1/PPARγ/PGC1α轴及其相关因子在骨关节炎脂质代谢中的作用

骨关节炎（osteoarthritis,OA）是一种退行性关节疾病,以软骨变性、骨硬化和慢性滑膜炎症为主要临床特征。在骨关节炎病理改变中,脂质代谢异常与软骨、骨的退行性改变密切相关。AMP活化的蛋白激酶（adenosine monophosphate?activated protein kinase,AMPK）活化后,可通过调节脂肪酸合成的关键酶,如肉碱脂酰转移酶（carnitine palmitoyltransferase 1,CPT?1）、链酰基辅酶A脱氢酶（medium chain acyl?CoA dehydrogenase,MCAD）和软骨细胞自噬功能,进而调节软骨细胞脂质代谢,以延缓OA的发展。过氧化物酶体增殖物激活受体γ（peroxisomal proliferator?activated receptor γ,PPARγ）和过氧化物酶体增殖物激活受体γ共激活因子1α（peroxisomal proliferator?activated receptor γ coactivator 1α,PGC?1α）也具有相似的生理功能。AMPK与沉默信息调节因子1（silencing information regulator 1,SIRT1）的激活及相互作用能介导PPARγ、PGC?1α的信号转导及生理功能。综述了AMPK/SIRT1/PPARγ/PGC1α轴在OA发病机制中的作用的最新进展,以期为OA的治疗及预防研究提供参考。     

Resveratrol inhibits lipid accumulation in the intestine of atherosclerotic mice and macrophages

Disordered intestinal metabolism is highly correlated with atherosclerotic diseases. Resveratrol protects against atherosclerotic diseases. Accordingly, this study aims to discover novel intestinal proatherosclerotic metabolites and potential therapeutic targets related to the anti‐atherosclerotic effects of resveratrol. An untargeted metabolomics approach was employed to discover novel intestinal metabolic disturbances during atherosclerosis and resveratrol intervention. We found that multiple intestinal metabolic pathways were significantly disturbed during atherosclerosis and responsive to resveratrol intervention. Notably, resveratrol abolished intestinal fatty acid and monoglyceride accumulation in atherosclerotic mice. Meanwhile, oleate accumulation was one of the most prominent alterations in intestinal metabolism. Moreover, resveratrol attenuated oleate‐triggered accumulation of total cholesterol, esterified cholesterol and neutral lipids in mouse RAW 264.7 macrophages by activating ABC transporter A1/G1‐mediated cholesterol efflux through PPAR (peroxisome proliferator‐activated receptor) α/γ activation. Furthermore, we confirmed that PPARα and PPARγ activation by WY14643 and pioglitazone, respectively, alleviated oleate‐induced accumulation of total cholesterol, esterified cholesterol and neutral lipids by accelerating ABC transporter A1/G1‐mediated cholesterol efflux. This study provides the first evidence that resveratrol abolishes intestinal fatty acid and monoglyceride accumulation in atherosclerotic mice, and that resveratrol suppresses oleate‐induced accumulation of total cholesterol, esterified cholesterol and neutral lipids in macrophages by activating PPARα/γ signalling.     

Inhibition of the actions of peroxisome proliferator-activated receptor alpha on obesity by estrogen

Objective: To determine whether the major ovarian factor estrogen modulates peroxisome proliferator‐activated receptor (PPAR) α actions on obesity and to investigate the mechanism by which estrogen regulates PPARα actions. Research Methods and Procedures: Female ovariectomized mice were randomly divided into four groups (n = 8/group). After they were treated with combinations of high fat, fenofibrate (FF), or 17β‐estradiol (E) for 13 weeks, variables and determinants of obesity and lipid metabolism were measured using in vivo and in vitro approaches. Results: When female ovariectomized mice were given a high‐fat diet with either FF or E, body weight gain and white adipose tissue mass were significantly reduced and serum lipid profiles were improved compared with control mice fed a high‐fat diet alone. When mice were concomitantly treated with FF and E, however, E reversed the effects of FF on body weight gain, serum lipid profiles, and hepatic PPARα target gene expression. Consistent with the in vivo data, E not only decreased basal levels of PPARα reporter gene activation but also significantly decreased Wy14,643‐induced luciferase reporter activity. In addition, inhibition of PPARα functions by E did not seem to occur by interfering with the DNA binding of PPARα. Discussion: Our results demonstrate that in vivo and in vitro treatment of estrogen inhibited the actions of FF‐activated PPARα on obesity and lipid metabolism through changes in the expression of PPARα target genes, providing evidence that FF does not regulate obesity in female mice with functioning ovaries.