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Gene expression changes in ketogenic and high-fat diets

ABSTRACT: The ketone body β-hydroxybutyrate (BHB) is produced during dietary restriction, fasting, and exercise. A ketogenic diet (KD) results in long-term production of BHB outside of these contexts. We sought to determine a protein-matched, non-obese ketogenic diet (KD) would affect the longevity and healthspan of C57BL/6 male mice. We find that feeding KD every-other-week to prevent obesity (cyclic KD) reduces mid-life mortality but does not affect maximum lifespan. Similar feeding of a non-ketogenic high-fat/low-carbohydrate (HF) diet may have an intermediate effect on mortality. Cyclic KD improves memory performance in old age, while modestly improving composite measures of healthspan. RNAseq gene expression analysis identifies down-regulation of insulin, TOR, and fatty acid synthesis pathways as possible longevity mechanisms common to KD and HF. However, up-regulation of fasting-related PPARα target genes is unique to KD, consistent across tissues, and preserved in old age, suggesting a mechanism for an incremental benefit from KD. In all, we show that a non-obese ketogenic diet improves survival, memory, and healthspan into old age. These gene expression studies were carried out on 12 month-old male C56BL/6 mice from the NIA Aged Rodent Colony, habituated to AIN-93M control diet and then either maintained on this diet or switched for one week to a 75% kcal fat non-ketogenic high-fat diet or a 90% kcal fat ketogenic diet (all diets with 10% kcal from carbohydrates). Tissues were harvested in the middle of the nighttime feeding period (MN-3am).

ORGANISM(S): Mus musculus

PROVIDER: GSE101657 | GEO | 2017/09/05

SECONDARY ACCESSION(S): PRJNA395093

REPOSITORIES: GEO

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Project description:Beta-hydroxybutyrate (BHB) is a ketone body synthesized during fasting or strenuous exercise. Our previous study demonstrated that a cyclic ketogenic diet (KD), which induces BHB levels similar to fasting every other week, reduces midlife mortality and improves memory in aging mice. BHB actively regulates gene expression and inflammatory activation through non-energetic signaling pathways. Neither of these activities has been well-characterized in the brain and they may represent mechanisms by which BHB affects brain function during aging. First, we analyzed hepatic gene expression in an aging KD-treated mouse cohort using bulk RNA-seq. In addition to the downregulation of TOR pathway activity, cyclic KD reduces inflammatory gene expression in the liver. We observed via flow cytometry that KD also modulates age-related systemic T cell functions. Next, we investigated whether BHB affects brain cells transcriptionallyin vitro. Gene expression analysis in primary human brain cells (microglia, astrocytes, neurons) using RNA-seq shows that BHB causes a mild level of inflammation in all three cell types. However, BHB inhibits the more pronounced LPS-induced inflammatory gene activation in microglia. Furthermore, we confirmed that BHB similarly reduces LPS-induced inflammation in primary mouse microglia and bone marrow-derived macrophages (BMDMs). BHB is recognized as an inhibitor of histone deacetylase (HDAC), an inhibitor of NLRP3 inflammasome, and an agonist of the GPCR Hcar2. Nevertheless, in microglia, BHB's anti-inflammatory effects are independent of these known mechanisms. Finally, we examined the brain gene expression of 12-month-old male mice fed with one-week and one-year cyclic KD. While a one-week KD increases inflammatory signaling, a one-year cyclic KD reduces neuroinflammation induced by aging. In summary, our findings demonstrate that BHB mitigates the microglial response to inflammatory stimuli, like LPS, possibly leading to decreased chronic inflammation in the brain after long-term KD treatment in aging mice.

Project description:The prevalence of the metabolic syndrome (MS) is rapidly increasing all over the world. Consequently, there is an urgent need for more effective intervention strategies. Both animal and human studies indicate that lipid oversupply to skeletal muscle can result in insulin resistance which is one of the charecteristices of the MS. C57BL/6J mice were fed a low fat (10 kcal%) palm oil diet or a high fat (45 kcal%; HF) palm oil diet for 3 or 28 days. By combining transcriptomics with protein and lipid analyses we aimed to better understand the molecular events underlying the early onset of the MS. Short-term HF-feeding led to altered expression levels of genes involved in a variety of biological processes including morphogenesis, energy metabolism, lipogenesis and immune function. Protein analysis showed increased levels of the myosin heavy chain, slow fiber type protein and the complexes II, III, IV and V of the oxidative phosphorylation. Furthermore, we observed that the main mitochondrial membrane phospholipids, phosphatidylcholine and phosphatidylethanolamine, contained more saturated fatty acids. Altogether, these results point to a morphological as well as a metabolic adaptation by promoting a more oxidative fiber type. We hypothesize that after this early adaptation, a continued transcriptional down-regulation of genes involved in oxidative phosphorylation will result in decreased oxidative capacity at a later stage. Together with increased saturation of phospholipids of the mitochondrial membrane this can result in decreased mitochondrial function which is a hallmark observed in insulin resistance and type 2 diabetes. Keywords: diet intervention and time course In the present study we investigated the short versus the long term effects of a high fat diet on the mouse muscle transcriptome by performing a genome-wide analysis of high fat diet-responsive genes. C57BL/6J mice were fed a low fat (LF) diet (10 kcal% palm oil) or a high fat (HF) diet (45 kcal% palm oil) for 3 or 28 days. Total RNA samples (n = 6 per diet per time point) were individually hybridised tot the Affymatrix mouse genome 430 2.0 array.

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Gene expression changes in ketogenic and high-fat diets

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