Transcription profiling of mouse primaty hepatocytes reveals a coactivation screen identifies BAF60a as a regulator of lipid metabolism through PGC-1alpha
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
SUBMITTER: Siming Li
PROVIDER: E-GEOD-9523 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Impaired mitochondrial function has been implicated in the pathogenesis of type 2 diabetes, heart failure and neurodegeneration as well as during aging. Studies with the PGC-1 transcriptional coactivators have demonstrated that these factors are key components of the regulatory network that controls mitochondrial function in mammalian cells. Here we describe a genome-wide coactivation assay to globally identify the transcriptional partners for PGC-1α. These analyses revealed a molecular signature of the PGC-1α transcriptional network, and identified BAF60a (Smarcd1), a subunit of the SWI/SNF chromatin-remodeling complex, as a critical regulator of lipid homeostasis. Adenoviral-mediated expression of BAF60a stimulates fatty acid β-oxidation in cultured hepatocytes and reduces hepatic triglyceride levels in diet-induced obese mice. BAF60a physically interacts with PGC-1α and is recruited to PPARα target genes in the fasted liver. Liver-specific RNAi knockdown of BAF60a impairs fatty acid oxidation and results in severe hepatic steatosis following starvation. These results define a role for the SWI/SNF complexes in the regulation of hepatic lipid metabolism, and reveal a potential target for therapeutic intervention. Keywords: Adenoviral transduction.
2008-08-01 | GSE9523 | GEO
Project description:The transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) is a chief activator of the mitochondrial and metatolic program in skeletal muscle (skm) and prevents atrophy. Here we tested whether PGC-1α overexpression could restructure the transcriptome and metabolism of cultured human skeletal myotubes, which display an athropic phenotype. An oligonucleotide microarray analysis was used to reveal PGC-1α effects on the whole transcriptome, and the possible impact on fuel metabolism reprogramming was examined. Fifty-three different genes displayed changed expression levels in response to PGC-1α: 42 upregulated and 11 downregulated. Main associations of gene ontologies (GO) for the upregulated genes were mitochondrial components and processes and this correlated with an increase in COX activity, an indicator of mitochondrial content. Palmitate and lactate oxidation to CO2 was enhanced, but not glucose oxidation. The other most significant GO associations of upregulated genes were chemotaxis and cytokine activity, and accordingly, several cytokines, including IL8, CXCL6, CCL5 and CCL8, were within top induced genes. Among the most regulated genes were also potential metabolic regulators of fatty acid and glucose storage. FITM1/FIT1 induction was associated with an increased number of lipid droplets with smaller area, while triglyceride levels were modestly increased in oleate-incubated cells. Downregulation of CALM1, the calcium-modulated δ subunit of phosphorylase kinase, was linked to inactivation of glycogen phosphorylase and greater accumulation of glycogen. The most upregulated gene was PVALB, which is also related to calcium signaling. In conclusion, only the deficient mitochondrial transcriptional program of cultured myotubes is rescued by PGC-1α. New PGC-1α gene targets and pathways arise, some of which may mediate its activating effects in processes such as lipid and carbohydrate storage and angiogenesis. 6 samples from 3 different skeletal muscle cell cultures were used: 3 were transfected with adenovirus containing PGC-1aplha and 3 with adenovirus containing GFP (control). The 3 PGC-1alpha samples were compared against the control samples.
2012-03-15 | E-GEOD-28206 | biostudies-arrayexpress
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).
2014-03-28 | E-GEOD-56321 | biostudies-arrayexpress
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.
2014-03-28 | GSE56321 | GEO
Project description:Mutations in the gene encoding lipin 1 cause hepatic steatosis in fld mice, a genetic model of lipodystrophy. Lipin 1 appears to be highly involved in the control of fatty acid metabolism. Lipin 1 is most often located in the nucleus, but other studies suggest that lipin also has effects in the cytoplasm. However, the molecular function of lipin 1 is unclear. To evaluate the effects of activation of the lipin 1 system in liver, lipin 1beta was overexpressed in mouse liver using an adenoviral vector. We found that lipin 1 overexpression increased the expression of many genes involved in mitochondrial fatty acid oxidation while repressing expression of genes involved in lipogenesis. We believe that lipin is a transcriptional coactivator of the peroxisome proliferator-activated receptor (PPAR) complex. However, the many molecular aspects of its function remain unclear. Abstract of published manuscript follows:; Lipin 1 is an inducible amplifier of the hepatic PGC-1alpha/PPARalpha regulatory pathway.Finck BN, Gropler MC, Chen Z, Leone TC, Croce MA, Harris TE, Lawrence JC Jr, Kelly DP. Center for Cardiovascular Research and Washington University School of Medicine, St. Louis, Missouri 63110; Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110. Perturbations in hepatic lipid homeostasis are linked to the development of obesity-related steatohepatitis. Mutations in the gene encoding lipin 1 cause hepatic steatosis in fld mice, a genetic model of lipodystrophy. However, the molecular function of lipin 1 is unclear. Herein, we demonstrate that the expression of lipin 1 is induced by peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha), a transcriptional coactivator controlling several key hepatic metabolic pathways. Gain-of-function and loss-of-function strategies demonstrated that lipin selectively activates a subset of PGC-1alpha target pathways, including fatty acid oxidation and mitochondrial oxidative phosphorylation, while suppressing the lipogenic program and lowering circulating lipid levels. Lipin activates mitochondrial fatty acid oxidative metabolism by inducing expression of the nuclear receptor PPARalpha, a known PGC-1alpha target, and via direct physical interactions with PPARalpha and PGC-1alpha. These results identify lipin 1 as a selective physiological amplifier of the PGC-1alpha/PPARalpha-mediated control of hepatic lipid metabolism. Experiment Overall Design: Adult male C57BL6 mice were injected with adenovirus driving expression of mouse lipin 1beta or green fluorescent protein (GFP). Mice were recovered and sacrificed 6 days after injection. Total RNA was isolated and analyzed using Affymetrix microarray.
2008-06-13 | E-GEOD-5538 | biostudies-arrayexpress
Project description:Mutations in the gene encoding lipin 1 cause hepatic steatosis in fld mice, a genetic model of lipodystrophy. Lipin 1 appears to be highly involved in the control of fatty acid metabolism. Lipin 1 is most often located in the nucleus, but other studies suggest that lipin also has effects in the cytoplasm. However, the molecular function of lipin 1 is unclear. To evaluate the effects of activation of the lipin 1 system in liver, lipin 1beta was overexpressed in mouse liver using an adenoviral vector. We found that lipin 1 overexpression increased the expression of many genes involved in mitochondrial fatty acid oxidation while repressing expression of genes involved in lipogenesis. We believe that lipin is a transcriptional coactivator of the peroxisome proliferator-activated receptor (PPAR) complex. However, the many molecular aspects of its function remain unclear. Abstract of published manuscript follows: Lipin 1 is an inducible amplifier of the hepatic PGC-1alpha/PPARalpha regulatory pathway.Finck BN, Gropler MC, Chen Z, Leone TC, Croce MA, Harris TE, Lawrence JC Jr, Kelly DP. Center for Cardiovascular Research and Washington University School of Medicine, St. Louis, Missouri 63110; Department of Medicine, Washington University School of Medicine, St. Louis, Missouri 63110. Perturbations in hepatic lipid homeostasis are linked to the development of obesity-related steatohepatitis. Mutations in the gene encoding lipin 1 cause hepatic steatosis in fld mice, a genetic model of lipodystrophy. However, the molecular function of lipin 1 is unclear. Herein, we demonstrate that the expression of lipin 1 is induced by peroxisome proliferator-activated receptor gamma (PPARgamma) coactivator 1alpha (PGC-1alpha), a transcriptional coactivator controlling several key hepatic metabolic pathways. Gain-of-function and loss-of-function strategies demonstrated that lipin selectively activates a subset of PGC-1alpha target pathways, including fatty acid oxidation and mitochondrial oxidative phosphorylation, while suppressing the lipogenic program and lowering circulating lipid levels. Lipin activates mitochondrial fatty acid oxidative metabolism by inducing expression of the nuclear receptor PPARalpha, a known PGC-1alpha target, and via direct physical interactions with PPARalpha and PGC-1alpha. These results identify lipin 1 as a selective physiological amplifier of the PGC-1alpha/PPARalpha-mediated control of hepatic lipid metabolism. Keywords: response to lipin 1 activation
2006-08-16 | GSE5538 | GEO
Project description:The class 3 phosphoinositide 3-kinase (PI3K) is required for the lysosomal degradation by autophagy and vesicular trafficking, assuring adaptation to energy shortages. Mitochondrial lipid catabolism is another important energy source. Autophagy and mitochondrial metabolism are transcriptionally controlled by nutrient sensing nuclear receptors. However, it is not known whether the class 3 PI3K contributes to this regulation. Here we show that hepatocyte-specific inactivation of Vps15, the essential regulatory subunit of the class 3 PI3K, results in mitochondrial depletion and a failure to oxidize fatty acids. Mechanistically, the transcriptional activity of Peroxisome Proliferator Activated Receptor alpha (PPARα), a nuclear receptor that orchestrates fatty acid catabolism, is blunted in Vps15-deficient livers. We find PPARα transcriptional repressors Histone Deacetylase 3 (Hdac3) and Nuclear receptor co-repressor 1 (NCoR1) accumulated in Vps15-deficient livers due to defective autophagic flux. Pharmacologic activation of PPARα with a synthetic ligand, re-expression of its co-activator Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha (PGC-1α) or inhibition of Hdac3 restored mitochondrial biogenesis and lipid oxidation in Vps15-deficient hepatocytes. These findings reveal a role for the class 3 PI3K and autophagy in transcriptional coordination of mitochondrial metabolism.
2020-02-06 | E-MTAB-7685 | biostudies-arrayexpress
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.
2016-06-16 | E-GEOD-76079 | biostudies-arrayexpress
Project description:*Objectives:* In addition to their well-known role in the control of cellular proliferation and cancer, cell cycle regulators are increasingly identified as important metabolic modulators. Genome wide association studies identified SNPs near the cell cycle regulator CDKN2A/p16INK4a (p16) as strongly associated with risk of developing type 2 diabetes (T2D). T2D is associated with numerous perturbations of hepatic lipid and glucose metabolism. We have recently shown that p16 controls fasting-induced hepatic gluconeogenesis in mice. However, whether p16 may also affect hepatic lipid homeostasis is unknown. *Results:* In primary hepatocytes, p16-deficiency was associated with elevated expression of genes involved in fatty acid catabolism and enhanced activation of PPAR. This led to increased mitochondrial fatty acid oxidation (FAO) through a mechanism requiring the catalytic AMPK 2 subunit and SIRT1. By contrast, *p16* overexpression was associated with triglyceride accumulation and increased lipid droplet numbers *in vitro*, and decreased ketogenesis and hepatic mitochondrial activity *in vivo*. Gene expression analysis of human liver samples revealed a negative correlation between *CDKN2A* expression and *PPARA* and its target genes, suggesting a potential association between hepatic p16 expression and FAO in obese humans. *Conclusions:* Our findings demonstrate that p16 plays a key role in hepatic lipid metabolism and may thus contribute to the development of metabolic diseases.
2020-10-09 | GSE134625 | GEO
Project description:BACKGROUND & AIMS: Nonalcoholic steatohepatitis (NASH) is a chronic liver disease characterized by hepatic lipid accumulation, inflammation, and progressive fibrosis. Acetyl-CoA carboxylase (ACC) catalyzes the rate-limiting step of de novo lipogenesis and regulates fatty-acid beta-oxidation in hepatocytes. ACC inhibition reduces hepatic fat content and markers of liver injury in NASH patients; however, the effect of ACC inhibition on liver fibrosis has not been reported. METHODS: A direct role for ACC in fibrosis was evaluated by measuring de novo lipogenesis, procollagen production, gene expression, glycolysis, and mitochondrial respiration in hepatic stellate cells (HSCs) in the absence or presence of small-molecule inhibitors of ACC. ACC inhibitors were evaluated in rodent models of liver fibrosis induced by diet or the hepatotoxin, DEN. Fibrosis and hepatic steatosis were evaluated by histological and biochemical assessments. RESULTS: In TGF-beta-stimulated HSCs, ACC inhibition reduced activation and collagen production independent of mitochondrial beta-oxidation by blocking de novo lipogenesis. ACC inhibition prevented a metabolic switch necessary for induction of glycolysis and oxidative phosphorylation during HSC activation. Consistent with this direct anti-fibrotic mechanism in HSCs, ACC inhibition reduced liver fibrosis in a rat CDHFD model and in response to chronic DEN-induced liver injury that lacked hepatic lipid accumulation. CONCLUSIONS: In addition to reducing lipid accumulation in hepatocytes, ACC inhibition also directly impairs the pro-fibrogenic activity of HSCs. Small molecule inhibitors of ACC may reduce liver fibrosis by both reducing lipotoxicity in hepatocytes and directly reducing HSC activation, providing a mechanistic rationale for the treatment of patients with advanced liver fibrosis due to NASH.
2020-04-24 | GSE148849 | GEO