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. Twelve-week old male BALB/cByJ (Acads-/-) and BALB/cByKZ (Acads+/+) mice were fed a high-fat (D12331; Research Diets) and low-fat (D12329) diet for two days. Total RNA from whole brain tissue was obtained from three mutant (Acads-/-) and three wild-type (Acads+/+) mice of each diet group. All mice had similar body weights before diets were initiated. Gene expression in brain was compared between strains and between diets. Twelve-week old male BALB/cByJ (Acads-/-) and BALB/cByKZ (Acads+/+) mice were fed a high-fat (D12331; Research Diets) and low-fat (D12329) diet for two days. Total RNA from liver was obtained from three mutant (Acads-/-) and three wild-type (Acads+/+) mice of each diet group. All mice had similar body weights before diets were initiated. Gene expression in liver was compared between strains and diets.

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.

Project description:Age-related and/or high caloric intake driven changes in visceral adipose tissue contribute to the development of diabetes and cardiovascular disease. The lack of reliable, high-throughput methods to analyze the adipose tissue protein composition has limited our understanding of the protein networks responsible for metabolic regulation of various adipose depots. We have developed a proteomic approach using multiple-dimension liquid chromatography tandem mass spectrometry and multiplexed TMT labeling to analyze protein composition of epididymal adipose tissues isolated from mice fed either low or high fat diet for a short (8 weeks) or a long (18 weeks) term, and from mice that aged (26 weeks old) on low vs. high fat diets. Advancing age and high-fat diet feeding led to graded deterioration, with long-term high fat diet exposure being the worst of all measures of peripheral metabolic health such as body weight, adiposity, plasma fasting glucose, insulin, triglycerides, total cholesterol levels, and glucose and insulin tolerance tests. Epididymal adipose depot proteomic analysis identified >3300 proteins per sample. In response to short-term high fat diet, 43 proteins representing lipid metabolism (e.g., AACS, ACOX1, ACLY) and red-ox pathways (e.g., CPD2, CYP2E, SOD3) were significantly altered (FDR < 10%). Long-term high fat diet significantly altered 55 proteins associated with immune response (e.g., IGTB2, IFIT3, LGALS1) and rennin angiotensin system (e.g. ENPEP, CMA1, CPA3, ANPEP). Age-related changes on low fat diet significantly altered only 18 proteins representing mainly urea cycle (e.g., OTC, ARG1, CPS1), and amino acid biosynthesis (e.g., GMT, AKR1C6). Surprisingly, high fat diet driven age-related changes culminated with alterations in 155 proteins involving primarily the urea cycle (e.g., ARG1, CPS1), immune response/complement activation (e.g., C3, C4b, C8, C9, CFB, CFH, FGA), extracellular remodeling (e.g., EFEMP1, FBN1, FBN2, LTBP4, FERMT2, ECM1, EMILIN2, ITIH3) and apoptosis (e.g., YAP1, HIP1, NDRG1, PRKCD, MUL1) pathways. Our unbiased mass spectrometry method, tailored to adipose tissue, identified both age-related and high fat diet specific proteomic signatures. In addition to well-described immune and extracellular remodeling response to high fat feeding, we have uncovered the pronounced involvement of arginine metabolism in response to advancing age, and branched chain amino acid metabolism in early response to high fat feeding. We were able to uncouple age-related metabolic responses from those associated with caloric intake, a task otherwise difficult to achieve.

Dataset Information

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure