Project description:Cancer cells exhibit an aberrant metabolism which facilitates more efficient production of biomass, and hence tumor growth and progression. The genetic cues modulating this metabolic switch remain largely undetermined, however. Here we identify a metabolic function for PML which reveals an unexpected role for this bona-fide tumor suppressor in pro-survival activity in breast cancer. We find that PML acts as both a negative regulator of PGC1A acetylation and as a potent activator of peroxisome proliferator-activated receptor (PPAR) signaling and fatty acid oxidation (FAO). We further show that as FAO PML promotes ATP production, inhibits anoikis, and allows luminal filling in 3D basement membrane breast culture models. Furthermore, analysis of breast cancer biopsies reveals that PML is over-expressed in a subset of breast cancers, and is enriched in triple-negative cases. Indeed, PML expression in breast cancer correlates strikingly with reduced time to recurrence, a gene signature of poor prognosis and activated PPAR signaling. These findings have important therapeutic implications, as PML and its key role in FAO metabolism are amenable to pharmacological suppression as a mode of cancer prevention and treatment. Mouse livers from Pml-WT and Pml-KO mice were harvested after 20 week diet with high fat diet (60% Cal from fat; Harlan 06414) or control diet (10% Cal from fat; Harlan 08806). Mice were fasted for 8h prior to tissue harvesting in order to avoid the effect of immediate food intake. 3 tissue extracts per genotype and condition were analyzed (out of a total of 8 mice per group).
Project description:Cancer cells exhibit an aberrant metabolism which facilitates more efficient production of biomass, and hence tumor growth and progression. The genetic cues modulating this metabolic switch remain largely undetermined, however. Here we identify a metabolic function for PML which reveals an unexpected role for this bona-fide tumor suppressor in pro-survival activity in breast cancer. We find that PML acts as both a negative regulator of PGC1A acetylation and as a potent activator of peroxisome proliferator-activated receptor (PPAR) signaling and fatty acid oxidation (FAO). We further show that as FAO PML promotes ATP production, inhibits anoikis, and allows luminal filling in 3D basement membrane breast culture models. Furthermore, analysis of breast cancer biopsies reveals that PML is over-expressed in a subset of breast cancers, and is enriched in triple-negative cases. Indeed, PML expression in breast cancer correlates strikingly with reduced time to recurrence, a gene signature of poor prognosis and activated PPAR signaling. These findings have important therapeutic implications, as PML and its key role in FAO metabolism are amenable to pharmacological suppression as a mode of cancer prevention and treatment.
Project description:The small heterodimer partner (SHP) regulates fatty acid oxidation and lipogenesis in the liver by regulating peroxisome proliferator-activated receptor (PPAR) γ expression. SHP is also abundantly expressed in the myocardium. Therefore, we investigated the myocardial gene expression in a SHP deletion animal model.
Project description:Hepatic metabolic derangements are key components in the development of fatty liver, insulin resistance, and atherosclerosis. SIRT1, a NAD+-dependent protein deacetylase, is an important regulator of energy homeostasis in response to nutrient availability. Here we demonstrate that hepatic SIRT1 regulates fatty acid metabolism by positively regulating PPAR-alpha. Hepatocyte-specific deletion of SIRT1 impairs PPAR-alpha signaling and decreased fatty acid beta-oxidation in the liver. When challenged with a high-fat diet, liver-specific SIRT1 knockout mice develop hepatic steatosis, hepatic inflammation, and endoplasmic reticulum stress. Taken together, our data indicate that SIRT1 plays a vital role in the regulation of hepatic lipid homeostasis.
Project description:Here, we show that short term HFD feeding did not change the cardiac function in normal (Con) and increased FAO mice (ACC2 iKO). RNA sequencing analysis show that ACC2 can have small but significant genetic perturbations impact on the global transcriptome under chow and HFD condition. Most of fatty acid degradation and PPAR signaling pathway related gene transcription levels were decreased by knocking out ACC2. Intriguingly, cardiac transcriptome analysis of several lipotoxicity mouse models showed an opposite regulation direction of PPAR signaling pathway and fatty acid degradation genes. Finally, fatty acid degradation gene transcription was found back to normal in iKO-HFD mouse hearts compared to Con-chow mice hearts. These results suggest that fatty acid availability may play an important role in PPAR signaling regulation regardless the fatty acid oxidation rate, at least in mice heart.
Project description:Histone deacetylase 3 (Hdac3) regulates the expression of lipid metabolism genes in multiple tissues, however its role in regulating lipid metabolism in the intestinal epithelium is unknown. Here we demonstrate that intestine-specific deletion of Hdac3 (Hdac3IKO) protects mice from diet induced obesity. Intestinal epithelial cells (IECs) from Hdac3IKO mice display co-ordinate induction of genes and proteins involved in mitochondrial and peroxisomal b-oxidation, have an increased rate of fatty acid oxidation, and undergo marked remodelling of their lipidome, particularly a reduction in long chain triglycerides. Many HDAC3-regulated fatty oxidation genes are transcriptional targets of the PPAR family of nuclear receptors, Hdac3 deletion enhances their induction by PPAR-agonists, and pharmacological HDAC3 inhibition induces their expression in enterocytes. These findings establish a central role for HDAC3 in co-ordinating PPAR-regulated lipid oxidation in the intestinal epithelium, and identify intestinal HDAC3 as a potential therapeutic target for preventing obesity and related diseases.
Project description:Sirtuins are a family of protein deacetylases, deacylases, and ADP-ribosyltransferases that regulate life span, control the onset of numerous age-associated diseases, and mediate metabolic homeostasis. We have uncovered a novel role for the mitochondrial sirtuin SIRT4 in the regulation of hepatic lipid metabolism during changes in nutrient availability. We show that SIRT4 levels decrease in the liver during fasting and that SIRT4 null mice display increased expression of hepatic peroxisome proliferator activated receptor (PPAR ) target genes associated with fatty acid catabolism. Accordingly, primary hepatocytes from SIRT4 knockout (KO) mice exhibit higher rates of fatty acid oxidation than wild-type hepatocytes, and SIRT4 overexpression decreases fatty acid oxidation rates. The enhanced fatty acid oxidation observed in SIRT4 KO hepatocytes requires functional SIRT1, demonstrating a clear cross talk between mitochondrial and nuclear sirtuins. Thus, SIRT4 is a new component of mitochondrial signaling in the liver and functions as an important regulator of lipid metabolism. SIRT4 knockout (KO) and wild-type (WT) littermates (male; n 6 per genotype; 7- to 8-month-old littermates) were sacrificed after a 16-h overnight fast. Samples were individually hybridized on Affymetrix Mouse Genome 430 2.0 GeneChips by the Biopolymers Facility (Harvard Medical School).
Project description:Sirtuins are a family of protein deacetylases, deacylases, and ADP-ribosyltransferases that regulate life span, control the onset of numerous age-associated diseases, and mediate metabolic homeostasis. We have uncovered a novel role for the mitochondrial sirtuin SIRT4 in the regulation of hepatic lipid metabolism during changes in nutrient availability. We show that SIRT4 levels decrease in the liver during fasting and that SIRT4 null mice display increased expression of hepatic peroxisome proliferator activated receptor (PPAR ) target genes associated with fatty acid catabolism. Accordingly, primary hepatocytes from SIRT4 knockout (KO) mice exhibit higher rates of fatty acid oxidation than wild-type hepatocytes, and SIRT4 overexpression decreases fatty acid oxidation rates. The enhanced fatty acid oxidation observed in SIRT4 KO hepatocytes requires functional SIRT1, demonstrating a clear cross talk between mitochondrial and nuclear sirtuins. Thus, SIRT4 is a new component of mitochondrial signaling in the liver and functions as an important regulator of lipid metabolism.
Project description:Obesity is a major risk factor for the development of insulin resistance and type II diabetes. The nuclear receptors PPAR delta and PPAR gamma play a central role in regulating metabolism in adipose tissue, as well as being targets for the treatment of insulin resistance. The metabolic effects of PPAR delta and PPAR gamma activation have been examined both in vivo in white adipose tissue from ob/ob mice and in vitro in cultured 3T3-L1 adipocytes using a combined 1H NMR spectroscopy and mass spectrometry metabolomic methodology to understand the contrasting roles of these receptors. These steady state measurements were supplemented with 13C-stable isotope substrate labeling to assess fluxes, respirometry and transcriptomic microarray analysis. The metabolic effects of the two receptors were readily distinguished, with PPAR gamma ?activation characterised by increased fat storage and fat synthesis/elongation, while activation of PPAR delta caused increased fatty acid beta-oxidation, TCA cycle rate and oxidation of extracellular branch chain amino acids. Stimulated glycolysis and increased desaturation of fatty acids were the only common pathways. PPAR delta has a role as an anti-obesity target as well as an anti-diabetic. Total RNA obtained from cultured 3T3-L1 cells treated for 48 hours with either DMSO control, GW610742 PPARd agonist or GW347845 PPARg agonist and compared.