Project description:To understand the transcriptional effect of fasting and feeding a ketogenic diet on mouse CNS astrocytes, we performed translating ribosomal affinity purification (TRAP) of mRNAs immunoprecipitated from hippocampus. TRAP mice express a ribosomal epitope tag upon Cre-induced recombination that can be immunoprecipitated following activation. We measured the abundance of actively translating mRNAs from a ribosomal pull-down that came from adult astrocyte (Aldh1l1-Cre)-specific TRAP mice that were subjected to one of three dietary conditions: four weeks of normal chow diet, four weeks of ketogenic diet (high-fat, low-carbohydrate)43, or an 18-hour fast. Immediately following the respective diets, forebrain and hippocampus was harvested from all groups, ribosomes were immunoprecipitated, and actively translating mRNAs in the ribosomes were purified.
Project description:To maintain homeostasis, the body including the brain reprograms its metabolism in response to altered nutrition or disease. However, the consequences of these challenges for the energy metabolism of the different brain cell types remain unknown. Here, we generated a proteome atlas of the major CNS cell types from young and adult mice, after feeding the therapeutically relevant low-carbohydrate, high-fat ketogenic diet (KD) and during neuroinflammation. Under steady-state conditions, CNS cell types prefer distinct modes of energy metabolism. Surprisingly, the comparison with KD revealed distinct cell type-specific strategies to manage the altered availability of energy metabolites. Astrocytes and neurons but not oligodendrocytes demonstrated metabolic plasticity. Unexpectedly, inflammatory demyelinating disease changed the neuronal metabolic signature in a similar direction as KD. Together, these findings highlight the importance of the metabolic crosstalk between CNS cells and between the periphery and the brain to manage altered nutrition and neurological disease.
Project description:The ketogenic diet (KD) is an established treatment for patients with medically intractable epilepsy and is chiefly characterized by the production of ketone bodies (KB) such as β-hydroxybutyrate (BHB). However, after more than a century of clinical use, the mechanisms underlying its efficacy remain unclear. While prior investigations have examined the effects of the KD and its metabolic substrates on synaptic transmission, few studies have explored a potential connection between astrocytic ion channels and seizure genesis. One essential function of astrocytes is spatial potassium buffering which influences passive potassium conductance (PPC), and when impaired, can result in neuronal hyperexcitability. In the present study, we demonstrate that the KD can mitigate hippocampal astrogliosis in the Kcna1-null (KO) mouse model of developmental epilepsy. Specifically, we observed a significant increase in GFAP expression in KO mice fed a control diet compared to wild-type (WT) animals, and that the KD prevented this change. Furthermore, we noted a reduction in hippocampal astrocytic PPC in epileptic mice, whereas KD-treated KO animals exhibited nearly normal passive conductance levels. In this regard, we also provide evidence for the role of Kir4.1 channels in mediating astrocytic PPC, and the activation of these inwardly rectifying potassium channels by BHB. To further explore these findings at a molecular level, we conducted bulk RNA-seq analysis which revealed down-regulation of factors linked to hippocampal astrogliosis, notably those involved with neuroinflammation, consistent with earlier reports highlighting the anti-inflammatory effects of the KD and its metabolic substrates such as BHB. Our findings indicate that the KD protects against epilepsy-associated astrogliosis and astrocytic PPC changes, underscoring a novel mechanism of KD action, and the potential functional role of extracellular potassium in neuronal-glial interactions in the epileptic brain.
Project description:Kabuki syndrome is a Mendelian intellectual disability syndrome caused by mutations in either of two genes (KMT2D and KDM6A) involved in chromatin accessibility. We previously showed that an agent that promotes chromatin opening, the histone deacetylase inhibitor (HDACi) AR-42, ameliorates the deficiency of adult neurogenesis in the granule cell layer of the dentate gyrus, and rescues hippocampal memory defects in a mouse model of Kabuki syndrome (Kmt2d+/βGeo). Unlike a drug, a dietary intervention could be quickly transitioned to the clinic. Therefore, we have explored whether treatment with a ketogenic diet could lead to a similar rescue through increased amounts of beta-hydroxybutyrate, an endogenous HDACi. Here, we report that a ketogenic diet in Kmt2d+/βGeo mice modulates H3ac and H3K4me3 in the granular cell layer, with concomitant rescue of both the neurogenesis defect and hippocampal memory abnormalities seen in Kmt2d+/βGeo mice; similar effects on neurogenesis were observed upon exogenous administration of beta-hydroxybutyrate. These data suggests that dietary modulation of epigenetic modifications through elevation of beta-hydroxybutyrate may provide a feasible strategy to treat the intellectual disability seen in Kabuki syndrome and related disorders. We used microarrays to query global gene expression changes in the hippocampus of wild type and Kmt2d+/βGeo (Kabuki syndrome model) mice on a regular diet to identify specific gene expression abnormalities in the hippocampus of the Kabuki syndrome mouse model.
Project description:The ketogenic diet has long been used to treat epilepsy, but its mechanism is not yet clearly understood. To explore the potential mechanism, the changes in gene expression induced by the ketogenic diet in the rat kainic acid (KA) epilepsy model were analyzed. Two-condition experiment, Normal diet-fed rat brain vs. Ketogenic diet-fed rat brain. Duplicate per array
Project description:Specific pathogen free wild-type C57Bl/6 male mice fed ketogenic diet (Bio-Serv AIN-76-A) for 4 weeks Keywords: RNA Expression Array Hearts from 12 week-old mice that were maintained on a standard polysacchardide-rich chow until the age of 8 weeks, at which time they were switched to a ketogenic diet (ad libitum) and maintained for 4 additional weeks prior to collection of tissues
Project description:To maintain homeostasis, the body including the brain reprograms its metabolism in response to altered nutrition or disease. However, the consequences of these challenges for the energy metabolism of the different brain cell types remain unknown. Here, we generated a proteome atlas of the major CNS cell types from young and adult mice, after feeding the therapeutically relevant low-carbohydrate, high-fat ketogenic diet (KD) and during neuroinflammation. Under steady-state conditions, CNS cell types prefer distinct modes of energy metabolism. Surprisingly, the comparison with KD revealed distinct cell type-specific strategies to manage the altered availability of energy metabolites. Astrocytes and neurons but not oligodendrocytes demonstrated metabolic plasticity. Unexpectedly, inflammatory demyelinating disease changed the neuronal metabolic signature in a similar direction as KD. Together, these findings highlight the importance of the metabolic crosstalk between CNS cells and between the periphery and the brain to manage altered nutrition and neurological disease.