Project description:A high phosphorus (HP) diet causes disorders of renal function, bone metabolism, and vascular function. We previously demonstrated that DNA microarray analysis is an appropriate method to comprehensively evaluate the effects of a HP diet on kidney dysfunction such as calcification, fibrillization, and inflammation. We reported that type IIb sodium-dependent phosphate transporter is significantly up-regulated in this context. In the present study, we performed DNA microarray analysis to investigate the effects of a HP diet on the liver, which plays a pivotal role in energy metabolism. DNA microarray analysis was performed with total RNA isolated from the livers of rats fed a control diet (containing 0.3% phosphorus) or a HP diet (containing 1.2% phosphorus). Gene Ontology analysis of differentially expressed genes (DEGs) revealed that the HP diet induced down-regulation of genes involved in hepatic amino acid catabolism and lipogenesis, while genes related to fatty acid β-oxidation process were up-regulated. Although genes related to fatty acid biosynthesis were down-regulated in HP diet-fed rats, genes important for the elongation and desaturation reactions of omega-3 and -6 fatty acids were up-regulated. Concentrations of hepatic arachidonic acid and eicosapentaenoic acid were increased in HP diet-fed rats. These essential fatty acids activate peroxisome proliferator-activated receptor alpha (PPARα), a transcription factor for fatty acid β-oxidation. Evaluation of the upstream regulators of DEGs using Ingenuity Pathway Analysis indicated that PPARα was activated in the livers of HP diet-fed rats. Furthermore, the serum concentration of fibroblast growth factor 21, a hormone secreted from the liver that promotes fatty acid utilization in adipose tissue as a PPARα target gene, was higher (p = 0.054) in HP diet-fed rats than in control diet-fed rats. These data suggest that a HP diet enhances energy expenditure through the utilization of free fatty acids released via lipolysis of white adipose tissue.

Project description:In plants, fatty acids are de novo synthesized predominantly in plastids fromacetyl-CoA. Although fatty acid biosynthesis has been biochemically well-studied, little isknown about the regulatory mechanisms of the pathway. Here, we show that overexpressionof the Arabidopsis (Arabidopsis thaliana) LEAFY COTYLEDON1 (LEC1) gene causesglobally increased expression of fatty acid biosynthetic genes, which are involved in keyreactions of condensation, chain elongation and desaturation of fatty acid biosynthesis. Inthe plastidial fatty acid synthetic pathway, over 58% of known enzyme-coding genes areupregulated in LEC1-overexpressing transgenic plants, including those encoding threesubunits of acetyl-CoA carboxylase, a key enzyme controlling the fatty acid biosynthesisflux. Moreover, genes involved in glycolysis and lipid accumulation are also upregulated.Consistent with these results, levels of major fatty acid species and lipids were substantiallyincreased in the transgenic plants. Genetic analysis indicates that the LEC1 function ispartially dependent on ABSCISIC ACID INSENSITIVE3, FUSCA3 and WRINKLED1 in theregulation of fatty acid biosynthesis. Moreover, a similar phenotype was observed intransgenic Arabidopsis plants overexpressing two LEC1-like genes of Brassica napus.These results suggest that LEC1 and LEC1-like genes act as key regulators to coordinate theexpression of fatty acid biosynthetic genes, thereby representing a promising target forgenetic improvement of oil-production plants. Experiment Overall Design: The pER8-LEC1 transgenic seedlings were germinated and grown in the presence of 10 ÂµM estradiol for 4 days. The control sample was germinated and grown under the identical conditions without estradiol but containing 0.1% DMSO. Total RNA was prepared from fresh or frozen plant materials using the RNAeasy Plant Mini Kit (Qiagen China, Beijing). The first strand cDNA was synthesized, and then hybridized with the ATH1 oligonucleotide chips as described by the manufactureâs instructions (Affymetrix). The microarray hybridization data were collected and analyzed using related R (http://www.r-project.org/) packages provided by Bioconductor (http://www.biocoductor.org/). In brief, genes differentially expressed between wild type and mutant plants were selected by first removing âabsentâ genes which were never detected to be expressed in the experiments, then a two-side t-test was applied to remaining genes in order to test the expression difference between wide type and mutant plants. To avoid multiple testing problems, raw p-values were then adjusted into False Discovery Rate (FDR) using Benjamini and Hochberg approach. Finally, differentially expressed genes were defined as those FDR less than 0.2. Functional analysis of differentially expressed genes was carried out using the biological process category of Arabidopsis Gene Ontology. The hierarchical map of GO annotation was constructed according to the ontology tree provided by the Gene Ontology website (http://www.geneontology.com) as described previously (Zheng and Wang, 2008). Ontology categories that are significantly enriched among differentially expressed genes (hypergeometric test and FDR less than 0.1) were displayed as boxes in the map.

Project description:A high phosphorus (HP) diet causes disorders of renal function, bone metabolism, and vascular function. We previously demonstrated that DNA microarray analysis is an appropriate method to comprehensively evaluate the effects of a HP diet on kidney dysfunction such as calcification, fibrillization, and inflammation. We reported that type IIb sodium-dependent phosphate transporter is significantly up-regulated in this context. In the present study, we performed DNA microarray analysis to investigate the effects of a HP diet on the liver, which plays a pivotal role in energy metabolism. DNA microarray analysis was performed with total RNA isolated from the livers of rats fed a control diet (containing 0.3% phosphorus) or a HP diet (containing 1.2% phosphorus). Gene Ontology analysis of differentially expressed genes (DEGs) revealed that the HP diet induced down-regulation of genes involved in hepatic amino acid catabolism and lipogenesis, while genes related to fatty acid Î²-oxidation process were up-regulated. Although genes related to fatty acid biosynthesis were down-regulated in HP diet-fed rats, genes important for the elongation and desaturation reactions of omega-3 and -6 fatty acids were up-regulated. Concentrations of hepatic arachidonic acid and eicosapentaenoic acid were increased in HP diet-fed rats. These essential fatty acids activate peroxisome proliferator-activated receptor alpha (PPARÎ±), a transcription factor for fatty acid Î²-oxidation. Evaluation of the upstream regulators of DEGs using Ingenuity Pathway Analysis indicated that PPARÎ± was activated in the livers of HP diet-fed rats. Furthermore, the serum concentration of fibroblast growth factor 21, a hormone secreted from the liver that promotes fatty acid utilization in adipose tissue as a PPARÎ± target gene, was higher (p = 0.054) in HP diet-fed rats than in control diet-fed rats. These data suggest that a HP diet enhances energy expenditure through the utilization of free fatty acids released via lipolysis of white adipose tissue. Male Wistar rats (4 weeks old) were purchased from Japan SLC Co. (Hamamatsu, Japan) and individually housed in metabolic cages under controlled conditions of 22Â±1Â°C and a 12-hour light/dark cycle (lights on from 08:00 to 20:00 daily). Two different diets containing 0.3% phosphorous (control diet) and 1.2% phosphorous (HP diet) were prepared based on the AIN-93G diet (Table 1).9) All rats were fed the control diet for a 7-day acclimatization period. After acclimatization, rats were divided into two groups of similar mean body weight (n = 5 each) and then fed either the control or the HP diet for 24 days. The animals were allowed to eat ad libitum and had free access to water (MilliQ water).The protocol for the animal experiments was approved by the Animal Use Committee of the Faculty of Agriculture at The University of Tokyo. Please note that the animals used in this study are identical to those used in GSE31973.

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