Unknown,Transcriptomics,Genomics,Proteomics

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Effects of 20 months Dietary Methionine Restriction on Hepatic Gene Expression in Fischer 344 Rats

ABSTRACT: Dietary methionine restriction (MR) has been shown to increase lifespan and decrease adiposity in rodents. This study was designed to examine the transcriptional effects of MR in metabolically relevant tissues. This experiment contains data from the liver. We analyzed MR-induced changes in gene expression using pooled RNA from liver of rats fed either a control purified amino acid diet (DL-methionine content of 0.86%) (CON) or a methionine-restricted diet (DL-methionine content of 0.172%)(MR). Rats were fed Purina rodent diet 5001 until 32 days of age and were then randomly assigned to be fed CON diet or MR diet for 20 months.

ORGANISM(S): Rattus norvegicus

SUBMITTER: Kirsten Stone

PROVIDER: E-GEOD-28482 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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Project description:Background: Poultry eggs are a low cost, high protein nutrient package that can be consumed as part of a quality diet. However, consumption of poultry egg products has been historically contentious, which highlights the importance of investigating impacts of long-term egg consumption on metabolic health. Objective: Our study utilized the zebrafish Danio rerio, a newly-defined model of human metabolic health, to understand the metabolic consequence of consuming egg products in lieu of other well-described protein sources. Methods: Reference diets were formulated to contain multi-source protein with casein and fish protein hydrolysate (CON; control protein sources), the protein sources of which have been vetted in numerous reference diets. These proteins were then replaced in part with either whole egg (WE; protein and lipid source), egg white (EW; protein source), wheat gluten (WG; cereal protein source), or a high lipid content diet containing a multi-source protein with casein and fish protein hydrolysate (HFCON; isonitrogenous and isolipidic with the WE diet) in a 34-week trial. Daily feeding was initiated at early juvenile life stage and terminated at late reproductive adult stage. Results: The amino acid composition of control vs egg product diets did not vary substantially, although methionine and lysine were apparently limiting in fish fed WG. At termination, fish fed EW as the protein source had similar weight gain and body composition to those fed the CON diet. Blood glucose, both fasting and postprandial, did not differ among any dietary treatment. Assessment of the liver transcriptome using RNAseq revealed no differential gene expression between zebrafish fed CON or WE diets. Zebrafish fed WG had lower weight gain in males. Conclusions: Long-term consumption of egg products promoted metabolic health equal to that of historically-relevant proteins. These data support the value of egg products for maintaining long-term metabolic health in animal diets.

Project description:Mice and diets. One-month-old male mice of the long-lived B6C3F1 strain were purchased from Harlan (Indianapolis, IN) and maintained as described after weaning (15). Mice were housed in groups of 4 per cage and fed a non-purified diet, PMI Nutrition International Product #5001 (Purina Mills, Richmond, IN). At 5 months of age, the mice were individually housed, and randomly assigned to one of two groups, control (CON) or long-term CR (LTCR). CON mice were fed 93 kcal per week of a defined control diet (AIN-93M, Diet No. F05312, BIO-SERV). LTCR mice were fed 52.2 kcal per week of a defined CR diet (AIN-93M 40% Restricted, Diet No. F05314, BIO-SERV). The LTCR mice consumed approximately 40% fewer calories than mice in the CON mice. The CR diet was enriched so that the CR mice consumed approximately the same amount of protein, vitamins, and minerals per gram body weight as the control mice. Experimental design. At 20 months of age, cohorts of mice in the CON group were randomly assigned to one of 7 experimental groups (Fig. 1). A CON group continued to be fed 93 kcal per week of control diet for 8 weeks. A CR8 group was fed 77 kcal per week of CR diet for 2 weeks, followed by 52.2 kcal per week of CR diet for 6 weeks. The remaining dietary groups were fed the control diets containing, respectively, metformin (MET; Sigma, St. Louis, MO), glipizide (GLIP; Sigma), GLIP plus MET (GM), rosiglitazone (ROS; Avandia, SmithKline Beecham) or soy isoflavone extract (SOY; NOVASOY 400, Life Extension Foundation) for 8 weeks at the dosages indicated in Table 1. The drugs were mixed with powdered control diet and cold-pressed into one gram pellets (BIO-SERV Inc.). At 0900, all mice were fed 2/7 of the weekly allotment of food on Monday and Wednesday and 3/7 on Friday. The mice had free access to acidified tap water. They were fasted for 48 hours and killed by cervical dislocation at 22 months of age. No signs of pathology were detected in the animals used for the studies reported (n=4 per group). Organs were removed rapidly, flash frozen, and stored in liquid nitrogen. The weights of the mice were monitored bi-weekly. Mouse weights are given in Table 1. Measurement of specific mRNA levels. Liver total RNA was isolated as described from livers of pathology-free mice in each group (n=4 per group) (13). mRNA levels were measured using Affymetrix mouse U74Av2 arrays according to standard Affymetrix protocols (Affymetrix). Probe set expression measurement and normalization. After hybridization and scanning, raw image files were converted to probe set data (*.CEL files) using Microarray Suite (MAS 5.0). Probe set data from all 32 arrays were simultaneously analyzed with the Robust multichip Average (RMA) method to generate normalized expression measures for each probe set (Fig. 2; Ref. 24) The data were further filtered to exclude probe data sets that were Absent across all 32 arrays according to the MAS 5.0 detection algorithm (1,47).

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Effects of 20 months Dietary Methionine Restriction on Hepatic Gene Expression in Fischer 344 Rats

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