Project description:The liver is critical for maintaining systemic energy balance during starvation. To understand the role of hepatic fatty acid β-oxidation on this process, we generated mice with a liver-specific knockout of carnitine palmitoyltransferase 2 (Cpt2L-/-), an obligate step in mitochondrial long-chain fatty acid β-oxidation. Surprisingly, Cpt2L-/- mice survived the perinatal period and a 24hr fast with sufficient blood glucose. The loss of hepatic fatty acid oxidation resulted in a significant loss in circulating ketones that remained unaltered by fasting. Fasting induced serum dyslipidemia, hepatic steatosis and adaptations in hepatic and systemic oxidative gene expression in Cpt2L-/- mice to maintain systemic energy homeostasis. Alternatively, feeding a ketogenic diet resulted in severe hepatomegaly, liver damage and death within one week with a complete absence of adipose triglyceride stores. These data show that hepatic fatty acid oxidation is not required for survival during acute food deprivation but essential for constraining adipocyte lipolysis and regulating systemic catabolism when glucose is limiting. In this dataset, we include the expression data obtained from dissected mouse liver from mice fasted for 24 hours with and without the deletion of carnitine palmitoyltransferase 2 (i.e. hepatocytes unable to beta-oxidize long chain fatty acids in mitochondria). WildType and KnockOut mice were fasted for 24 hours. Three biologic replicates were compared per class, thus six mice.
Project description:The liver is critical for maintaining systemic energy balance during starvation. To understand the role of hepatic fatty acid β-oxidation on this process, we generated mice with a liver-specific knockout of carnitine palmitoyltransferase 2 (Cpt2L-/-), an obligate step in mitochondrial long-chain fatty acid β-oxidation. Surprisingly, Cpt2L-/- mice survived the perinatal period and a 24hr fast with sufficient blood glucose. The loss of hepatic fatty acid oxidation resulted in a significant loss in circulating ketones that remained unaltered by fasting. Fasting induced serum dyslipidemia, hepatic steatosis and adaptations in hepatic and systemic oxidative gene expression in Cpt2L-/- mice to maintain systemic energy homeostasis. Alternatively, feeding a ketogenic diet resulted in severe hepatomegaly, liver damage and death within one week with a complete absence of adipose triglyceride stores. These data show that hepatic fatty acid oxidation is not required for survival during acute food deprivation but essential for constraining adipocyte lipolysis and regulating systemic catabolism when glucose is limiting. In this dataset, we include the expression data obtained from dissected mouse liver from mice fasted for 24 hours with and without the deletion of carnitine palmitoyltransferase 2 (i.e. hepatocytes unable to beta-oxidize long chain fatty acids in mitochondria).
Project description:The ketogenic diet has been successful in promoting weight loss among patients that have struggled with weight gain. This is due to the cellular switch in metabolism that utilizes liver-derived ketone bodies for the primary energy source rather than glucose. Fatty acid transport protein 2 (FATP2) is highly expressed in liver, small intestine, and kidney where it functions in both the transport of exogenous long chain fatty acids (LCFA) and in the activation to CoA thioesters of very long chain fatty acids (VLCFA). We have completed a multi-omic study of FATP2-null (Fatp2-/-) mice maintained on a ketogenic diet (KD) or paired control diet (CD), with and without a 24-hour fast (KD-fasted and CD-fasted) to address the impact of deleting FATP2 under high-stress conditions. Control (wt/wt) and Fatp2-/- mice were maintained on their respective diets for 4-weeks. Afterwards, half the population was sacrificed while the remaining were fasted for 24-hours prior to sacrifice. We then performed paired-end RNA-sequencing on the whole liver tissue to investigate differential gene expression. The differentially expressed genes mapped to ontologies such as the metabolism of amino acids and derivatives, fatty acid metabolism, protein localization, and components of the immune system’s complement cascade, and were supported by the proteome and histological staining.
Project description:Pyruvate has two major fates upon entry into mitochondria, the oxidative decarboxylation to acetyl-CoA or the biotin-dependent carboxylation to oxaloacetate via pyruvate carboxylase (Pcx). Here we have generated mice with a liver specific knockout of Pcx to understand its role in hepatic mitochondrial metabolism under disparate physiological states including a 24 hour fast, as well as ketogenic and high fat diets. These data ultimately show the requirement of Pcx-mediated anapleorsis in the liver under disparate metabolic conditions.
Project description:Effect of deletion of carnitine palmitoyltransferase2 on interscapular BAT gene expression upon adrenergic stimulation in thermoneutral acclimatized mice
Project description:Circadian (~24 hour) clocks exist in almost all types of living organism and play a fundamental role in regulating daily physiological and behavioural processes. The transcription factor BMAL1 (ARNTL) is thought to be one of the principal drivers of the molecular clock in mammals since its deletion abolishes 24-hour activity patterning, an important physiological output of the clockwork. However, whether or not Bmal1-/- mice can nevertheless display molecular 24-hour rhythms is unknown. Here, we determined whether Bmal1 function is necessary for daily molecular oscillations in two tissues – skin fibroblasts and liver. Unexpectedly, both tissues exhibited robust 24-hour oscillations over 2-3 days in the absence of any exogenous synchronizers such as daily light or temperature cycles. This demonstrates a competent 24-hour molecular pacemaker in Bmal1 knockouts. Indeed, molecular oscillations were pervasive throughout the transcriptome, proteome and phosphoproteome of Bmal1-/- mice. In particular, several proteins exhibited rhythmic phosphorylation in both Bmal1-proficient and -deficient cells, highlighting an unanticipated role for post-translational regulators in 24-hour rhythms in the absence of any known clock mechanisms.
Project description:Kupffer cells have been implicated in the pathogenesis of various liver diseases. However, their involvement in metabolic disorders of the liver, including fatty liver disease, remains unclear. The present study sought to determine the impact of Kupffer cells on hepatic triglyceride storage and to explore the possible mechanisms involved. To that end, C57Bl/6 mice rendered obese and steatotic by chronic high-fat feeding were treated for 1 week with clodronate liposomes, which cause depletion of Kupffer cells. Loss of expression of marker genes Cd68, F4/80, and Clec4f, and loss of Cd68 immunostaining verified almost complete removal of Kupffer cells from the liver. Also, expression of complement components C1, the chemokine (C-C motif) ligand 6 (Ccl6), and cytokines interleukin-15 (IL-15) and IL-1beta were markedly reduced. Importantly, Kupffer cell depletion significantly decreased liver triglyceride and glucosylceramide levels concurrent with increased expression of genes involved in fatty acid oxidation including peroxisome proliferator-activated receptor alpha (PPARalpha), carnitine palmitoyltransferase 1A (Cpt1alpha), and fatty acid transport protein 2 (Fatp2). Treatment of mice with IL-1beta decreased expression of PPARalpha and its target genes, which was confirmed in primary hepatocytes. Consistent with these data, IL-1beta suppressed human and mouse PPARalpha promoter activity. Suppression of PPARalpha promoter activity was recapitulated by overexpression of nuclear factor kappaB (NF-kappaB) subunit p50 and p65, and was abolished upon deletion of putative NF-kappaB binding sites. Finally, IL-1beta and NF-kappaB interfered with the ability of PPARalpha to activate gene transcription. CONCLUSION: Our data point toward important cross-talk between Kupffer cells and hepatocytes in the regulation of hepatic triglyceride storage. The effect of Kupffer cells on liver triglycerides are at least partially mediated by IL-1beta, which suppresses PPARalpha expression and activity. Expression profiling of livers from mice fed control, low-fat diet diet or high-fat diet for 20weeks with or without knockdown of Kupffer cells.
Project description:GPR146 is a susceptible gene associated with plasma cholesterol levels in humans, its physiological and molecular functions have not been fully characherized. In this study, we generated Gpr146 whole-body knockout mice and found that depletion of GPR146 led to substantilly reduced plasma total cholesterol levels. We used microarrays to detail the global programme of gene expression in liver of Gpr146 WT and KO male mice upon 6-hour refeeding after a 16-hour fast.
Project description:Feed restriction and L-carnitine infusion are known to affect the liver metabolism of dairy cows. In the present experiment the effects on liver transcriptome of feed restriction and L-carnitine abomasal infusion and the interaction of the two in mid-lactation Holstein dairy cows was assessed. Data clearly indicated a lack of transcriptomics effect by L-carnitine but a strong effect due to feed restriction. The functional analysis identified a overall reduction of cholesterol synthesis and oxidative phosphorylation and data suggested an increase flux toward gluconeogenesis and fatty acid oxidation. The liver biopsy was performed after 14 days of treatment in 8 Holstein dairy cows in a 2 x 2 factorial arrangment with 5 days washout between treatments. A dye-swap reference design (reference = mixture of RNA from several bovine tissues) was used.