Project description:In addition to high intracellular glucose level, the diabetic state is also characterized by altered metabolites, which are pivotal regulators of glucotoxic pathways. In this study we analyzed Bezafibrate (BEZ) treated Streptozotocin (STZ) mice, which showed improved glucose metabolism compared to untreated STZ controls. In order to identify the key molecules and pathways, which participate in the beneficial effects of BEZ, we analyzed the skeletal muscle, white adipose tissue (WAT) and liver samples of BEZ-treated mice using non-targeted metabolomics (NMR spectroscopy), targeted metabolomics (mass spectrometry), microarrays and enzyme activity measurements with a particular focus on the liver. The analysis of muscle and WAT demonstrated that BEZ improved the expressions of genes and levels of metabolites, which could partly regulate the beneficial effects of BEZ on the glucose metabolism. Furthermore, in the liver, BEZ treatment reduced the elevated hepatic fumarate level of STZ mice, which was accompanied by a decreased expression of urea cycle genes. Since the urea cycle is involved in the production of fumarate, which is shown to be participated in glucotoxic pathways, our data suggest that BEZ could attenuate the urea cycle, reduce fumarate level and in turn ameliorate glucotoxicity in the liver of STZ mice
Project description:In addition to high intracellular glucose level, the diabetic state is also characterized by altered metabolites, which are pivotal regulators of glucotoxic pathways. In this study we analyzed Bezafibrate (BEZ) treated Streptozotocin (STZ) mice, which showed improved glucose metabolism compared to untreated STZ controls. In order to identify the key molecules and pathways, which participate in the beneficial effects of BEZ, we analyzed the skeletal muscle, white adipose tissue (WAT) and liver samples of BEZ-treated mice using non-targeted metabolomics (NMR spectroscopy), targeted metabolomics (mass spectrometry), microarrays and enzyme activity measurements with a particular focus on the liver. The analysis of muscle and WAT demonstrated that BEZ improved the expressions of genes and levels of metabolites, which could partly regulate the beneficial effects of BEZ on the glucose metabolism. Furthermore, in the liver, BEZ treatment reduced the elevated hepatic fumarate level of STZ mice, which was accompanied by a decreased expression of urea cycle genes. Since the urea cycle is involved in the production of fumarate, which is shown to be participated in glucotoxic pathways, our data suggest that BEZ could attenuate the urea cycle, reduce fumarate level and in turn ameliorate glucotoxicity in the liver of STZ mice
Project description:Glucotoxic metabolites and pathways play a crucial role in diabetic complications, and new treatment options which improve glucotoxicity are highly warranted. In this study, we analyzed bezafibrate (BEZ) treated, streptozotocin (STZ) injected mice, which showed an improved glucose metabolism compared to untreated STZ animals. In order to identify key molecules and pathways which participate in the beneficial effects of BEZ, we studied plasma, skeletal muscle, white adipose tissue (WAT) and liver samples using non-targeted metabolomics (NMR spectroscopy), targeted metabolomics (mass spectrometry), microarrays and mitochondrial enzyme activity measurements, with a particular focus on the liver. The analysis of muscle and WAT demonstrated that STZ treatment elevated inflammatory pathways and reduced insulin signaling and lipid pathways, whereas BEZ decreased inflammatory pathways and increased insulin signaling and lipid pathways, which can partly explain the beneficial effects of BEZ on glucose metabolism. Furthermore, lysophosphatidylcholine levels were lower in the liver and skeletal muscle of STZ mice, which were reverted in BEZ-treated animals. BEZ also improved circulating and hepatic glucose levels as well as lipid profiles. In the liver, BEZ treatment reduced elevated fumarate levels in STZ mice, which was probably due to a decreased expression of urea cycle genes. Since fumarate has been shown to participate in glucotoxic pathways, our data suggests that BEZ treatment attenuates the urea cycle in the liver, decreases fumarate levels and, in turn, ameliorates glucotoxicity and reduces insulin resistance in STZ mice.
Project description:Bezafibrate (BEZ), a pan activator of peroxisome proliferator-activated receptors (PPARs), is generally used to treat hyperlipidemia. Clinical trials on patients suffering from type 2 diabetes indicated that BEZ also has beneficial effects on glucose metabolism, but the underlying mechanisms remain elusive. Much less is known about the function of BEZ in type 1 diabetes. Here, we show that BEZ treatment markedly improves hyperglycemia, glucose and insulin tolerance in streptozotocin (STZ)-treated mice, an insulin-deficient mouse model of type 1 diabetes presenting with very high blood glucose levels. Furthermore, BEZ-treated mice also exhibited improved metabolic flexibility as well as an enhanced mitochondrial mass and function in the liver. Our data demonstrate a beneficial effect of BEZ treatment on STZ mice reducing diabetes and suggest that BEZ ameliorates impaired glucose metabolism possibly via augmented hepatic mitochondrial performance, improved insulin sensitivity and metabolic flexibility. We performed gene expression microarray analysis on liver tissue derived from streptozotocin-treated mice treated with bezafibrate in addition.
Project description:Bezafibrate (BEZ), a pan activator of peroxisome proliferator-activated receptors (PPARs), is generally used to treat hyperlipidemia. Clinical trials on patients suffering from type 2 diabetes indicated that BEZ also has beneficial effects on glucose metabolism, but the underlying mechanisms remain elusive. Much less is known about the function of BEZ in type 1 diabetes. Here, we show that BEZ treatment markedly improves hyperglycemia, glucose and insulin tolerance in streptozotocin (STZ)-treated mice, an insulin-deficient mouse model of type 1 diabetes presenting with very high blood glucose levels. Furthermore, BEZ-treated mice also exhibited improved metabolic flexibility as well as an enhanced mitochondrial mass and function in the liver. Our data demonstrate a beneficial effect of BEZ treatment on STZ mice reducing diabetes and suggest that BEZ ameliorates impaired glucose metabolism possibly via augmented hepatic mitochondrial performance, improved insulin sensitivity and metabolic flexibility.
Project description:A functional interaction between peroxisome proliferator-activated receptor alpha (PPARalpha) and components of the circadian clock has been suggested; however, it remains to be clarified whether those transcriptional factors interact with each other to regulate the expression of their target genes. In this study, we used a ligand of PPARalpha, bezafibrate, to search the PPARalpha-regulated genes that express in a CLOCK-dependent circadian manner. Microarrays analyses using hepatic RNA isolated from bezafibrate treated-wild type, Clock mutant (Clk/Clk), and PPARalpha-null mice revealed that 136 genes are transcriptionally regulated by PPARalpha in a CLOCK-dependent manner. Clk/Clk mutant mice with Jcl:ICR background, wild-type mice with the same strain, and PPARalpha-null mice aged 6-12 weeks were housed under a 12 h light-12 h dark cycle [LD 12:12; lights on at Zeitgeber time (ZT) 0]. For chronic treatment of bezafibrate, mice were provided with either a normal diet or the same diet containing 0.5% w/w bezafibrate for 5 days. A white fluorescent lamp provided light (300 - 500 lux at cage level) during the day. To examine the transient effect of bezafibrate injection on hepatic gene expression, bezafibrate was dissolved in warm (~40 C) sterile corn oil (Sigma) at a concentration of 10 mg/ml and administered intraperitoneally (i.p.) in a single dose of 100 mg/kg body weight at ZT2. To examine the PPARalpha-regulated genes that express in a CLOCK-dependent manner in mice, we performed oligonucleotide microarray analysis at ZT14, when CLOCK/BMAL1 transcriptional activity is maximal, using RNA isolated from wild-type (n = 3), Clock mutant (n = 3), and PPARalpha-null mice (n = 3) treated with bezafibrate for 5 days, and control wild-type mice (n = 3). Livers were collected and frozen in liquid nitrogen. Total RNA (250 ng) was extracted using RNAiso.
Project description:A functional interaction between peroxisome proliferator-activated receptor alpha (PPARalpha) and components of the circadian clock has been suggested; however, it remains to be clarified whether those transcriptional factors interact with each other to regulate the expression of their target genes. In this study, we used a ligand of PPARalpha, bezafibrate, to search the PPARalpha-regulated genes that express in a CLOCK-dependent circadian manner. Microarrays analyses using hepatic RNA isolated from bezafibrate treated-wild type, Clock mutant (Clk/Clk), and PPARalpha-null mice revealed that 136 genes are transcriptionally regulated by PPARalpha in a CLOCK-dependent manner.