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.

Project description:How signals from fatty acid metabolism are translated into changes in food intake remains unclear. Previously we reported that mice with a genetic inactivation of Acads (short-chain acyl-CoA dehydrogenase), encoding the enzyme responsible for mitochondrial beta-oxidation of C4-C6 short-chain fatty acids (SCFAs), shift consumption away from fat and toward carbohydrate when offered a choice. This finding demonstrated that the loss of a specific enzyme in fatty acid oxidation alters the choice of diet intake. To our knowledge, there are no reports of studies on the effects of dietary fat on the brain transcriptome in genetic models of fatty acid oxidation deficiency. The current study aimed to identify molecular mediators underlying the effects of SCFA oxidation deficiency on food intake. The current study aimed to identify molecular mediators underlying the effects of SCFA oxidation deficiency on food intake. We performed a transcriptional screen for gene expression in brain tissue of Acads-/- and Acads+/+ mice fed either high-fat (HF) or low-fat (LF) diet for 2 d. Ingenuity Pathway Analysis revealed three top-scoring pathways significantly modified by genotype or diet: oxidative phosphorylation, mitochondrial dysfunction, and CREB signaling in neurons. A comparison of statistically significant responses in HF Acads-/- vs. HF Acads+/+ (3917) and Acads+/+ HF vs. LF Acads+/+ (3879) revealed 2551 genes or approximately 65% in common between the two experimental comparisons. All but one of these genes were expressed in opposite direction with similar magnitude, demonstrating that Acads-deficient mice fed HF diet display transcriptional responses that mimic those of wildtype Acads+/+ mice fed LF diet. Intriguingly, genes involved in energy sensing and metabolism followed this pattern. Quantitative RT-PCR in hypothalamus confirmed the dysregulation of several genes in these pathways. Western blotting showed that the combination of Acads deficiency and HF diet increased hypothalamic AMP-kinase, a key protein in an energy-sensing cascade that responds to depletion of ATP. Our results suggest that the decreased beta oxidation of short-chain fatty acids in Acads-deficient mice fed HF diet produces a state of energy deficiency in the brain and that AMP-kinase is the cellular energy-sensing mechanism linking fatty acid oxidation to feeding behavior in this model.

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