mRNA Expression Levels Of PPARα Research Articles

In vitro study on antioxidant and lipid-lowering activities of tobacco polysaccharides

Tobacco polysaccharides were extracted by hot water extraction, and purified and separated using DEAE-52 cellulose chromatography columns, and three purified polysaccharide fractions, YCT-1, YCT-2, and YCT-3, were finally obtained. The physicochemical properties of the three fractions were analyzed by ultraviolet spectroscopy, high-performance liquid chromatography and high-performance gel chromatography. The in vitro antioxidant activity of tobacco polysaccharides was compared among different fractions by using DPPH radical, hydroxyl radical scavenging assay and potassium ferricyanide method. The in vitro hypoglycemic activity was compared using α-amylase and α-glucosidase activity inhibition assay. And the in vitro hypolipidemic activity were investigated by using pancreatic lipase activity inhibition assay and HepG-2 intracellular lipid accumulation assay. All the results showed that the constituent monosaccharides of the three tobacco polysaccharide fractions were similar, but the molar percentages of each monosaccharide were different. The average molecular weights of the three components were 27,727 Da, 27,587 Da, and 66,517 Da, respectively, and the scavenging activities on DPPH radicals and hydroxyl radicals were at a high level with good quantitative-effect relationships. The reducing power were much lower than that of the positive control VC, and the three polysaccharide fractions had a weak inhibitory ability on α-amylase activity, but showed excellent inhibitory ability on α-glucosidase and pancreatic lipase activity. In addition, the results of cellular experiments showed that all three fractions were able to inhibit lipid over-accumulation in HepG-2 cells by increasing the mRNA expression levels of PPAR-α, CPT-1A, and CYP7A1 genes, and the tobacco polysaccharide YCT-3 showed the best effect. The mechanism by which YCT-3 ameliorated the over-accumulation of intracellular lipids in HepG-2 cells was found to be related to its influence on the expression of miR-155-3p and miR-17-3p in the exosomes of HepG-2 cells.Graphical

Effects of phosphorus and fenofibrate on lipid deposition, mitochondrial function and protein synthesis in obscure puffer (Takifugu obscurus)

This study aimed to investigate the effects of phosphorus (P) restriction and fenofibrate (F) on lipid deposition, mitochondrial function and protein synthesis in obscure puffer using in vivo and in vitro studies. In vivo, healthy fish with an initial body weight of 18.21 ± 0.04 g were fed three diets supplemented with different P and fenofibrate contents for 10 weeks: Control (5.3 g/kg P), P0 (0 g/kg P) and P0 + F (0 g/kg P and 3.5 g/kg F). The results indicated that P0 treatment significantly reduced weight gain rate and protein deposition, but increased body lipid accumulation, hepatic lipid droplets and serum triglyceride and cholesterol content (P < 0.05). However, P0 + F treatment reversed these. Furthermore, P0 treatment was found to inhibit the mRNA levels of pparα, lpl and cyp7a1, whereas P0 + F treatment significantly increased the expression levels of these genes. In vitro, primary hepatocytes were cultured for 48 h in three different culture media: Control (normal DMEM medium), P0 (DMEM without P), and P0 + F (DMEM without P + 200 mM F). The results showed that P0 significantly decreased the mRNA and protein expression levels of Pparα (P < 0.05), and P0 + F up-regulated mRNA expression levels of pparα compared with P0 group (P < 0.05). Furthermore, P0 inhibited the expression levels of genes associated with fatty acid β-oxidation (cpt1 and acox1) and transport (cd36), but elevated the expression levels of genes related to lipid synthesis (fas, me, g6pd and dgat1) and cholesterol synthesis (hmgcr) (P < 0.05). However, P0 + F reversed these effects. P0 decreased mitochondrial abundance, membrane potential and ATP content, increased the mRNA expression level of ampk and 4epb1 and inhibited the mRNA expression of pgc1-α and the protein expression of mTOR and S6k (P < 0.05), whereas P0 + F increased mitochondrial abundance and membrane potential, increased mtor mRNA expression and inhibited 4ebp1 mRNA expression. Overall, this study suggests that P deficiency leads to lipid and cholesterol accumulation and impaired growth in fish, and fenofibrate can alleviate these effects by improving lipid and cholesterol metabolism, mitochondrial function, and protein synthesis.

Identify Molecular Mechanisms of Jiangzhi Decoction on Nonalcoholic Fatty Liver Disease by Network Pharmacology Analysis and Experimental Validation.

Background Jiangzhi Decoction (JZD), a traditional herb mixture, has shown significant clinical efficacy against nonalcoholic fatty liver disease (NAFLD). However, its multicomponent and multitarget characteristics bring difficulty in deciphering its pharmacological mechanisms. Our study is aimed at identifying the core molecular mechanisms of JZD against NAFLD. Methods The active ingredients were searched from Traditional Chinese Medicine Systems Pharmacology (TCMSP) database and Traditional Chinese Medicine Integrated Database (TCMID). The targets of those ingredients were identified using ChemMapper database based on 3D structure similarity. NAFLD-related genes were searched from DisGeNET database and Gene Expression Omnibus (GEO) database. Then, we performed protein-protein interaction (PPI) analysis, functional enrichment analysis, and constructed pathway networks of “herbs-active ingredients-candidate targets” and identified the core molecular mechanisms and key active ingredients in the network. Also, molecular docking was carried out to predict the ligands of candidate targets using SwissDock. Finally, the human hepatic L02 cell line was used to establish the NAFLD model in vitro. The effect and key molecules were validated by Oil Red O staining, biochemical assays, and quantitative real-time PCR (qRT-PCR). Results We found 147 active ingredients in JZD, 1285 targets of active ingredients, 401 NAFLD-related genes, and 59 overlapped candidate targets of JZD against NAFLD. 22 core targets were obtained by PPI analysis. Finally, nuclear receptor transcription and lipid metabolism regulation were found as the core molecular mechanisms of JZD against NAFLD by functional enrichment analysis. The candidate targets PPARα and LXRα were both docked with hyperin as the most favorable interaction, and HNF4α was docked with linolenic acid ethyl ester. According to in vitro experiments, it was found that JZD had an inhibitory effect on lipid accumulation and regulatory effects on cholesterol and triglycerides. Compared with OA group, the mRNA expression levels of PPARα and HNF4α were significantly upregulated in JZD group (P < 0.05), and LXRα was significantly downregulated (P < 0.001). Conclusion JZD might alleviate hepatocyte steatosis by regulating some key molecules related to nuclear receptor transcription and lipid metabolism, such as PPARα, LXRα, and HNF4α. Our study will provide the scientific evidences of the clinical efficacy of JZD against NAFLD.

PPARα plays an important role in the migration activity, and the expression of CYP2S1 and CYP1B1 in chrysin-treated HCT116 cells.

This study aimed to examine the metabolising effect of chrysin by investigating the mRNA expression levels of PPARα and its related cellular mechanisms in HCT116 cells. The mRNA expression of PPARα was significantly induced in HCT116 cells following treatment with chrysin for 36h, but the mRNA expression of PPARα was inhibited, when the cells were treated with a combination of chrysin and MK886 (PPARα inhibitor). This phenomenon proved that the incorporation of MK886 lowers the expression levels of PPARα, thus enabling us to study the function of PPARα. The cell population of the G0/G1 phase significantly increased in chrysin-treated cells, which was accompanied by a decrease in the percentage of S phase cell population after 12h of treatment. However, treatments of HCT116 cells with chrysin only or a combination of chrysin and MK886 did not show the opposite situation in the G0/G1 and S phase cell populations, indicating that the expression of PPARα may not be associated with the cell cycle in the treated cells. The migration rate in chrysin-treated HCT116 cells was reduced significantly after 24 and 36h of treatments. However, the activity was revived, when the expression of PPARα was inhibited, indicating that the migration activity of chrysin-treated cells is likely correlated with the expression of PPARα. Comparison of the CYP2S1 and CYP1B1 mRNA expression in chrysin only treated, and a combination of chrysin and MK886-treated HCT116 cells for 24 and 36h showed a significant difference in the expression levels, indicating that PPARα inhibitor could also modify the expression of CYP2S1 and CYP1B1. The study indicates that PPARα may play an essential role in regulating the migration activity, and the expression of CYP2S1 and CYP1B1 in chrysin-treated colorectal cancer cells.

Oleoylethanolamide supplementation in obese patients newly diagnosed with non-alcoholic fatty liver disease: Effects on metabolic parameters, anthropometric indices, and expression of PPAR-α, UCP1, and UCP2 genes

The effects of oleoylethanolamide (OEA) on NAFLD are yet to be examined in human. The objective of the present study was to examine the effects of OEA supplementation along with weight loss intervention on the expression of PPAR-α, uncoupling proteins 1and 2 (UCP1 and UCP2) genes in the peripheral blood mononuclear cells (PBMCs), metabolic parameters, and anthropometric indices among obese patients with NAFLD. In this triple-blind placebo-controlled randomized clinical trial, 76 obese patients newly diagnosed with NAFLD were randomly allocated into either OEA or placebo group along with calorie-restricted diets for 12 weeks. At pre-and post-intervention phase, mRNA expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, serum levels of metabolic parameters as well as diet and appetite sensations were assessed. There was a significant increase in the expression levels of PPAR-α, UCP1, and UCP2 genes in the PBMCs, compared to the placebo at the endpoint. A significant decrease in the anthropometric indices, energy and carbohydrate intakes, glycemic parameters, except for hemoglobin A1c concentration was also observed in the OEA group, compared to the placebo group. OEA treatment significantly resulted in decreased serum levels of triglyceride (TG), alanine aminotransferase (ALT), aspartate aminotransferase (AST), ALT/AST, increased serum levels of high-density lipoprotein cholesterol (HDL-C), and improved appetite sensations. Importantly, a significant improvement in TG, ALT, AST, ALT/AST, HDL-C levels as well as appetite sensations by OEA were under the influence of body mass index (BMI). Although liver steatosis severity was significantly reduced in both groups, the between-group differences did not reach statistical significance (P = 0.061). In conclusion, the present study, for the first time, revealed that OEA supplementation significantly improved anthropometric and metabolic risk factors related to NAFLD.

The effect of resveratrol supplementation on the expression levels of factors associated with cellular senescence and sCD163/sTWEAK ratio in patients with type 2 diabetes mellitus: study protocol for a double-blind controlled randomised clinical trial

IntroductionOver the past decades, the number of people with type 2 diabetes (T2D) has increased globally. One of the major complications in these patients is cardiovascular disease; it seems that...

Molecular characterization and tissue distribution of SREBP-1 and PPARα in Onychostoma macrolepis and their mRNA expressions in response to thermal exposure

Fatty acid metabolism is crucial for maintaining energy homeostasis in aquatic vertebrates experiencing environmental stress. Both sterol regulatory element-binding protein 1 (SREBP-1) and peroxisome proliferator-activated receptor α (PPARα) are the key regulators of fatty acid metabolism. In this study, the coding sequences (CDS) of SREBP-1 and PPARα were firstly identified and characterized from Onychostoma macrolepis, encoding peptides of 1136 and 470 amino acids, respectively. The functional domains in O. macrolepis SREBP-1 and PPARα proteins retained the high similarity with those of other animals, at 74.69% and 77.29%, respectively. The mRNA encoding SREBP-1 was primarily expressed in the muscle and PPARα was highly expressed in the liver and intestine. Under thermal exposure, the content of non-esterified fatty acid (NEFA) decreased gradually after 1 h in the liver and muscle of O. macrolepis, which might be due to that the organism meet more energy expenditure via fatty acid β-oxidation. Furthermore, the mRNA expression level of SREBP-1 decreased, while the mRNA expression level of PPARα increased from 0 h to 6 h in the liver. And we found that the mRNA expression levels of both SREBP-1 and PPARα decreased significantly at 48 h (P < .05) in the muscle, which was in accordance with the significant decrease of target gene FAS and CPT1A mRNA expression levels, respectively. It might be the physiological adjustment that the fish adapted to thermal exposure at the end of experiment. These results illustrate that O. macrolepis SREBP-1 and PPARα-mediated fatty acid metabolism is a fundamental requirement for thermal adaptation.

Effect of polysaccharides from Polygonatum sibiricum on lipid-metabolism related mRNA and protein expression in hyperlipidemic mice

To study the effect of polysaccharides from Polygonatum sibiricum on mRNA and protein expressions of blood lipid metabolism in hyperlipidemic mice. The mice were randomly divided into 6 groups, namely the blank control group, the hyperlipidemia model group, the simvastatin group, and low, middle and high-dose PSP groups (200, 400, 800 mg·kg⁻¹·d⁻¹). Each group of the mice was administrated intragastrically for 14 days, respectively. Subsequently, every group of mice, except for the blank control group, was intraperitoneally injected with 75% fresh egg yolk emulsion for establishing the hyperlipidemic mice model. Upon completion of the administration, the contents of TC, TG, LDL-C and HDL-C in serum of each group were investigated in details. In particular, the mRNA expression levels of PPAR-α, PPAR-β, PPAR-γ, SREBP-1c, IL-6 and TNF-α of the liver tissues were detected by Real-time PCR, and the protein expression levels (including PPAR-α, PPAR-β, PPAR-γ, SREBP-1c, IL-6, TNF-α) were examined by Western blot. Consequently, the obtained results showed that the contents of the serum TC, TG, LDL-C of low, middle and high-dose PSP groups significantly decreased compared with those of the hyperlipidemia model group. Simultaneously, there were significant differences between middle-dose and high-dose PSP groups (P<0.01). In striking contrast, the contents of serum HDL-C of low, middle and high-dose PSP groups significantly increased, while obvious differences were also observed between middle-dose and high-dose PSP groups (P<0.01). Moreover, middle-dose and high-dose PSR groups could up-regulate the protein and mRNA expressions of PPAR-α, PPAR-β (P<0.05) compared with those of the hyperlipidemia model group, and down-regulate the expressions of PPAR-γ,SREBP-1c, IL-6 and TNF-α(P<0.05) compared with those of liver tissues of the hyperlipidemia model group. In conclusion, all of the above results suggested that PSP could inhibit the oxidation of the liver lipid, and regulate the expression levels of the corresponding genes and proteins relating to the lipid metabolism, so as to play a critical role for preventing hyperlipidemia.

In Vivo Effects of Lipopolysaccharide on Peroxisome Proliferator-Activated Receptor Expression in Juvenile Gilthead Seabream (Sparus Aurata).

Fish are constantly exposed to microorganisms in the aquatic environment, many of which are bacterial pathogens. Bacterial pathogens activate the innate immune response in fish involving the production of pro-inflammatory molecules that, in addition to their immune-related role, can affect non-immune tissues. In the present study, we aimed at investigating how inflammatory responses can affect metabolic homeostasis in the gilthead seabream (Sparus aurata), a teleost of considerable economic importance in Southern European countries. Specifically, we mimicked a bacterial infection by in vivo administration of lipopolysaccharide (LPS, 6 mg/kg body weight) and measured metabolic parameters in the blood and, importantly, the mRNA expression levels of the three isotypes of peroxisome proliferator activated receptors (PPARα, β, and γ) in metabolically-relevant tissues in seabream. PPARs are nuclear receptors that are important for lipid and carbohydrate metabolism in mammals and that act as biological sensors of altered lipid metabolism. We show here that LPS-induced inflammatory responses result in the modulation of triglyceride plasma levels that are accompanied most notably by a decrease in the hepatic mRNA expression levels of PPARα, β, and γ and by the up-regulation of PPARγ expression only in adipose tissue and the anterior intestine. In addition, LPS-induced inflammation results in an increase in the hepatic mRNA expression and protein activity levels of members of the mitogen-activated protein kinase (MAPK) family, known in mammals to regulate the transcription and activity of PPARs. Our results provide evidence for the involvement of PPARs in the metabolic response to inflammatory stimuli in seabream and offer insights into the molecular mechanisms underlying the redirection of metabolic activities under inflammatory conditions in vertebrates.

Relationship between PPARα mRNA expression and mitochondrial respiratory function and ultrastructure of the skeletal muscle of patients with COPD

ABSTRACTPeripheral muscle dysfunction is an important complication in patients with chronic obstructive pulmonary disease (COPD). The objective of this study was to explore the relationship between the levels of peroxisome proliferator-activated receptor α (PPARα) mRNA expression and the respiratory function and ultrastructure of mitochondria in the vastus lateralis of patients with COPD. Vastus lateralis biopsies were performed on 14 patients with COPD and 6 control subjects with normal lung function. PPARα mRNA levels in the muscle tissue were detected by real-time PCR. A Clark oxygen electrode was used to assess mitochondrial respiratory function. Mitochondrial number, fractional area in skeletal muscle cross-sections, and Z-line width were observed via transmission electron microscopy. The PPARα mRNA expression was significantly lower in COPD patients with low body mass index (BMIL) than in both COPD patients with normal body mass index (BMIN) and controls. Mitochondrial respiratory function (assessed by respiratory control ratio) was impaired in COPD patients, particularly in BMIL. Compared with that in the control group, mitochondrial number and fractional area were lower in the BMIL group, but were maintained in the BMIN group. Further, the Z-line became narrow in the BMIL group. PPARα mRNA expression was positively related to mitochondrial respiratory function and volume density. In COPD patients with BMIN, mitochondria volume density was maintained, while respiratory function decreased, whereas both volume density and respiratory function decreased in COPD patients with BMIL. PPARα mRNA expression levels are associated with decreased mitochondrial respiratory function and volume density, which may contribute to muscle dysfunction in COPD patients.

Effects of pure total flavonoids from Citrus changshan-huyou on blood lipid metabolism in hyperlipidemic rats

To observe and investigate the effects and mechanisms of the pure total flavonoids from Citrus changshan-huyou(PTFC) on blood lipid metabolism in hyperlipidemic rats. SD rats were fed with high fat diet for 4 weeks to induce hyperlipidemic rats model, meanwhile three dosages (50, 100, 200 mg•kg ⁻¹•d ⁻¹) of PTFC were administrated intragastrically for 4 weeks respectively.After 2 weeks of modeling, their tail blood was taken and serum TC, TG, and HDL-C levels were detected by biochemical method and their body weight was measured. After 4 weeks of modeling, their body weight was measured and liver weight was measured, then the levels of TC, TG, HDL-C, LDL-C, ALT, AST, MDA and SOD in serum were detected to calculate lipid comprehensive index(LDL-C/HDL-C and LDL-C/TC ratios) and atherogenic index(AI); in addition, MDA and SOD levels were detected by biochemical method. The hitopathological changes of the liver tissues were observed by HE staining; the protein expression levels of PPAR-α, Lpl, and Lipc were detected by ELISA; and the mRNA expression levels of PPAR-α in the liver tissue were detected by Real-time PCR. The results showed that gavage administration of the PTFC significantly decreased the body weight, liver weight, liver index, serum ALT and AST activities, the levels of serum TC, TG, LDL-C, LDL-C/HDL-C, AI and increased serum HDL and LDL/TC level. Moreover, the PTFC significantly enhanced SOD activity and decreased the concentration of MDA in serum and liver tissue. Further mechanism investigation indicated that PTFC inhibited serum lipid accumulation by increasing the expressions PPAR-α, Lpl, Lipc protein and PPAR-α mRNA of the liver tissues. PTFC could actively regulate blood lipid metabolism by ameliorating hepatic function, improving the body's antioxidant capacity, lowering levels of oxidative stress, as well as positively regulating the expression levels of PPAR-α, Lpl, Lipc protein and PPAR-α mRNA of the liver tissues in rats.

MK886 inhibits the pioglitazone-induced anti-invasion of MDA-MB-231 cells is associated with PPARα/γ, FGF4 and 5LOX.

The goal of this study was to determine the effects of PGZ and MK886 on the mRNA expression of PPARα and other associated genes in MDA-MB-231 cells, and the biological mechanisms induced by both drugs were also assessed. The levels of PPARα mRNA expression in PGZ-treated and MK886-treated MDA-MB-231 cells were determined using real-time PCR; the growth inhibitory effects of PGZ and MK886 were determined using the trypan blue exclusion assay; the induction of apoptosis by PGZ and MK886 was determined using DNA fragmentation assay and real-time PCR; and the invasion of PGZ-treated and MK886-treated MDA-MB-231 cells was determined using the wound healing and transwell migration assays. In addition, we correlated the expression of PPARα mRNA with other genes, including PPARγ, FGF4 and 5LOX, in drug-treated MDA-MB-231 cells. Our results demonstrated that the treatment of MDA-MB-231 cells with PGZ increased the expression of PPARα/γ mRNA and that this expression could be inhibited by treatment with MK886. Both drugs reduced the viability of MDA-MB-231 cells independently of PPARα/γ mRNA expression but did not induce apoptosis. The wound caused by invasion was not healed by PGZ-treated MDA-MB-231 cells, but it was healed by MK886-treated cancer cells, indicating that the reduction of invasion in PGZ-treated MDA-MB-231 cells was eliminated by treatment with MK886, and this finding was validated by the transwell migration assay. This phenomenon might also be associated with the expression of PPARα/γ, FGF4 and 5LOX mRNA in the treated cancer cells. This study provides useful information regarding the mRNA expression levels of PPARα and other related genes in MDA-MB-231 cells. These genes could be attractive targets for reducing the invasion of breast cancer.

Effect of Inorganic Dietary Selenium Supplementation on Selenoprotein and Lipid Metabolism Gene Expression Patterns in Liver and Loin Muscle of Growing Lambs.

Effect of selenium (Se) supplementation on the selenoprotein and lipid metabolism gene expression patterns in ruminants, especially in lambs is not yet fully understood. The aim of study was to evaluate the effect of Se supplementation on the messenger RNA (mRNA) expression patterns of selected selenoproteins and genes related to lipid metabolism in growing lambs. The experiment was conducted on 48 Polish Merino lambs divided into two groups (n = 24): control (C)—lambs fed with a basal diet (BD) with no Se supplementation, and supplemented (S)—lambs fed with a BD, supplemented with 0.5 mg Se/kg as sodium selenate for 8 weeks. Expression of 12 selenoproteins and six genes related to lipid metabolism was analyzed in the liver and longissimus dorsi (LD) muscle of growing lambs by qPCR. Significant differences were found in the expression of GPX1, GPX2, SEPM, SEPW1, SEP15, SEPGS2, and TXNRD1 in the liver, and GPX1, SEPP1, SEPN1, SEPW1, SEP15, and MSRB1 in the LD muscle between S and C lambs. Se supplementation mainly upregulated SEPW1, SEP15 (P < 0.001; P < 0.01) mRNA expression in the liver, and GPX1, SEPP1, SEPN1, SEPW1 (P < 0.001; P < 0.01) in the muscle of S group. On the other hand, significant decrease in GPX2 (P < 0.01), SEPM (P < 0.001), and SEPHS2 (P < 0.01) mRNA expression levels were observed in the liver of S group of lambs. Se supplementation did not affect PON1, LXRα, and PPARα mRNA expression levels, but a significant increase in mRNA levels of APOE and LPL in the LD muscle (P < 0.05) as well as LPL (P < 0.05) in the liver were noticed in the group of Se supplemented lambs. Our study confirmed that, in lambs, similarly to other species, mRNA expression patterns of several selenoproteins highly depend on dietary Se levels, and their expression is ruled by hierarchical principles and tissue-specific mechanisms. Moreover, the study showed that changes Se intake leads to different levels of genes expression related with lipid metabolism.

Wogonin ameliorates hyperglycemia and dyslipidemia via PPARα activation in db/db mice

Wogonin is a flavonoid extracted from the root of Scutellaria baicalensis Gerogi. We evaluated the therapeutic effects of wogonin using db/db mice. Mice received wogonin or vehicle by oral gavage for 2 weeks. Blood glucose, insulin, and cholesterol levels were measured, and liver morphology was observed with histopathological analysis. The mRNA expression levels of PPARα, PPARγ, and adiponectin in the liver and white adipose tissue (WAT) were determined by real-time PCR. Immunoblotting for AMPK and PPARγ, and adipocyte differentiation were investigated in vitro using 3T3-L1 cells. A luciferase assay was used to measure PPARα and PPARγ binding activity. The wogonin group showed decreased weight gain without a change in food intake and improved glucose tolerance. Serum insulin and cholesterol levels in the wogonin group were significantly decreased compared to those in the control group. The wogonin group also showed less accumulation of lipid droplets and glycogen in the liver. PPARα and PPARγ expression levels in the liver and WAT and adiponectin expression level in WAT in the wogonin group were higher than those in the control group. In 3T3-L1 cells, wogonin was shown to stimulate AMPK activation in a dose-dependent manner. The presence of wogonin did not affect adipocyte differentiation or PPARγ protein level during adipogenesis. Notably, wogonin enhanced PPARα but not PPARγ transactivation. These indicate that wogonin may have beneficial effects on glucose and lipid metabolism related to enhanced PPARα and adiponectin expression via AMPK activation. Importantly, wogonin did not cause deleterious effects, such as weight gain and fatty liver. Wogonin might be a useful therapeutic agent to treat type 2 diabetes.

Low-Carbohydrate, High-Protein Diet Affects Rhythmic Expression of Gluconeogenic Regulatory and Circadian Clock Genes in Mouse Peripheral Tissues

Recent studies have demonstrated that metabolic changes in mammals induce feedback regulation of the circadian clock. The present study evaluates the effects of a low-carbohydrate high-protein diet (HPD) on circadian behavior and peripheral circadian clocks in mice. Circadian rhythms of locomotor activity and core body temperature remained normal in mice fed with the HPD diet (HPD mice), suggesting that it did not affect the central clock in the hypothalamus. Two weeks of HPD feeding induced mild hypoglycemia without affecting body weight, although these mice consumed more calories than mice fed with a normal diet (ND mice). Plasma insulin levels were increased during the inactive phase in HPD mice, but increased twice, beginning and end of the active phase, in ND mice. Expression levels of the key gluconeogenic regulatory genes PEPCK and G6Pase were significantly induced in the liver and kidneys of HPD mice. The HPD appeared to induce peroxisome proliferator-activated receptor α (PPARα) activation, since mRNA expression levels of PPARα and its typical target genes, such as PDK4 and Cyp4A10, were significantly increased in the liver and kidneys. Circadian mRNA expression of clock genes, such as BMAL1, Cry1, NPAS2, and Rev-erbα, but not Per2, was significantly phase-advanced, and mean expression levels of BMAL1 and Cry1 mRNAs were significantly elevated, in the liver and kidneys of HPD mice. These findings suggest that a HPD not only affects glucose homeostasis, but that it also advances the molecular circadian clock in peripheral tissues. (Author correspondence: k-ooishi@aist.go.jp)

Peroxisome proliferator-activated receptor alpha in the human breast cancer cell lines MCF-7 and MDA-MB-231.

Peroxisome proliferator-activated receptor (PPAR) alpha is a ligand-activated transcription factor that has been linked with rodent hepatocarcinogenesis. It has been suggested that PPARalpha mRNA expression levels are an important determinant of rodent hepatic tumorigenicity. Previous work in rat mammary gland epithelial cells showed significantly increased PPARalpha mRNA expression in carcinomas, suggesting the possible role of this isoform in rodent mammary gland carcinogenesis. In this study we sought to determine whether PPARalpha is expressed and dynamically regulated in human breast cancer MCF-7 and MDA-MB-231 cells. Having established the presence of PPARalpha in both cell types, we then examined the consequence of PPARalpha activation, by its ligands Wy-14,643 and clofibrate, on proliferation. With real-time reverse transcriptase-polymerase chain reaction, we showed that PPARalpha mRNA was dynamically regulated in MDA-MB-231 cells and that PPARalpha activation significantly increased proliferation of the cell line. In contrast, PPARalpha expression in MCF-7 cells did not change with proliferation during culture and was present at significantly lower levels than in MDA-MB-231 cells. However, PPARalpha ligand activation still significantly increased the proliferation of MCF-7 cells. The promotion of proliferation in breast cancer cell lines following PPARalpha activation was in stark contrast to the effects of PPARgamma-activating ligands that decrease proliferation in human breast cancer cells. Our results established the presence of PPARalpha in human breast cancer cell lines and showed for the first time that activation of PPARalpha in human breast cancer cells promoted proliferation. Hence, this pathway may be significant in mammary gland tumorigenesis.