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Two circadian oscillatory mechanisms in the mouse liver

ABSTRACT: Genome-wide expression analysis of two circadian oscillatory mechanisms in the mouse liver To identify the genes of which the circadian expression is regulated by endogenous glucocorticoids, we performed DNA microarray analysis using hepatic RNA from adrenalectomized (ADX) and sham-operated mice. Mice were housed in a 12:12 h light-dark cycle (LD12:12; lights on at zeitgeber time (ZT) 0) for at least two weeks before the day of the experiment. Liver samples were dissected, quickly frozen, and stored in liquid nitrogen. Total RNA was purified from pools of 3 animal tissues collected at each time-point using ISOGEN (Nippon Gene Co., Ltd., Japan). Hybridization to Affymetrix GeneChip (MG-U74Av2) arrays proceeded as described (Oishi K et al., J Biol Chem, 278, 41519-41527, 2003). The average difference (AD) value for each gene was provided by GeneChip software. To identify putative glucocorticoid-regulated circadian genes, we compared AD values between two time points (ZT2 and ZT14) in sham operated and in ADX mice. We applied three criteria to the selection of putative glucocorticoid-regulated circadian genes: (i) the AD value is marked as “present” by the GeneChip software in at least one of two time points, (ii) the AD value exhibits a 2-fold or greater change in sham-operated mice and (iii) the fold change is below 2-fold in ADX mice. We identified 169 genes that fluctuated between day and night in the livers of sham-operated mice. Among these, 100 lost circadian rhythmicity in ADX mice. On the other hand, the circadian expression of clock or clock-related genes such as mPer2 and DBP remained almost totally intact in the liver of ADX mice. The present study showed that the circadian expression of one type of liver genes in the mouse is governed by core components of the circadian clock such as CLOCK and BMAL1, and the other depends on endogenous glucocorticoids. Keywords: parallel sample

ORGANISM(S): Mus musculus

PROVIDER: GSE2162 | GEO | 2005/11/14

SECONDARY ACCESSION(S): PRJNA91429

REPOSITORIES: GEO

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Project description:The circadian clock has been found to be associated with various diseases. We showed that 5/6 nephrectomy (5/6Nx) Clk/Clk mice, which show mutation in the gene encoding circadian locomotor output cycles (Clock) do not show aggravation of renal fibrosis because transforming growth factor-1 (Tgf-1) expression is not increased. In wild-type 5/6Nx kidneys, we found that retinoid, a metabolite of retinol, led to alteration of the expresion 24-h rhythm of Clock expression. Renal Tgf- 1 expression is activated by Clock and further aggravates renal dysfunction by causing fibrosis. We also showed that, in 5/6Nx mice fed a retinol-free diet, renal fibrosis and apoptosis are reduced, leading to a marked improvement in serum creatinine levels. Moreover, our study identified hepatic Cyp3a11 and Cyp26a1 as key retinol metabolism-related genes whose expression decreased in 5/6Nx mice. Our data indicated that the negative chain reaction of metabolic clock alteration in between the kidney and liver aggravates renal dysfunction. Differential gene expression between retinol (-) feeding and clock mutant in 5/6 nephrectomized mouse was measured on the kidney at 8 weeks after operation. Four-week-old male ICR mice (Charles River Japan, Inc., Yokohama, Japan) were housed in a light-controlled room (lights on from Zeitgeber time [ZT] 0 to ZT12) at 24 ± 1°C and 60 ± 10% humidity, with food and water available ad libitum. Mice were synchronized to the lighting conditions for 2 weeks before surgery. Male ICR mice (5 weeks old) were purchased from Charles River Japan, Inc. (Kanagawa, Japan). Clock mutant mice (C57BL/6J-ClockmlJt/J) were purchased from The Jackson Laboratory (Bar Harbor, ME, USA). We placed them in the ICR genetic background to enhance breeding robustness and care of the young. These mice were backcrossed using a Jcl:ICR background for more than eight generations. We prepared mouse models of CRF by 5/6Nx operation (Ope) under sodium pentobarbital (40 mg/kg, i.p.) or diethyl ether anesthesia. 5/6Nx was performed in two stages. In the first surgical procedure (at 6 weeks of age), two-thirds of the left kidney was removed by cutting off both poles. Seven days later, the right kidney was completely removed. After the operation, mice were housed for 8 weeks (until they were 16 weeks old) in order to achieve CRF. Sham-operated (Sham) mice were subjected to laparotomy on the same days as the procedure in the 5/6Nx mice. This method was also used for treating Clk/Clk mice. Retinol-free food (A minus) was purchased form KBT ORIENTAL CO., LTD. To investigate the influences of retinol-free feeding on kidney, mice were fed from the fourth week to the eighth week after an operation.

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Two circadian oscillatory mechanisms in the mouse liver

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