Expression data from (bezafibrate treated-wild type, Clock mutant, and PPARalpha-null) mouse liver

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.