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PPARα mouse liver cistrome

ABSTRACT: Autophagy is an evolutionally conserved catabolic process that recycles nutrients upon starvation and maintains cellular energy homeostasis1-3. Its acute regulation by nutrient sensing signaling pathways is well described, but its longer-term transcriptional regulation is not. The nuclear receptors PPARα and FXR are activated in the fasted or fed liver, respectively4,5. Here we show that both regulate hepatic autophagy. Pharmacologic activation of PPARα reverses the normal suppression of autophagy in the fed state, inducing autophagic lipid degradation, or lipophagy. This response is lost in PPARα knockout (PPARα-/-) mice, which are partially defective in the induction of autophagy by fasting. Pharmacologic activation of the bile acid receptor FXR strongly suppresses the induction of autophagy in the fasting state, and this response is absent in FXR knockout (FXR-/-) mice, which show a partial defect in suppression of hepatic autophagy in the fed state. PPARα and FXR compete for binding to shared sites in autophagic gene promoters, with opposite transcriptional outputs. These results reveal complementary, interlocking mechanisms for regulation of autophagy by nutrient status. Mouse liver PPARα cistromes in fed 8-week-old male WT or PPARα KO mice treated with or without its synthetic agonist ligand GW7647twice a day were generated by deep sequencing in quadruplicate using illumina

ORGANISM(S): Mus musculus

SUBMITTER: David Moore

PROVIDER: E-GEOD-61817 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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PPARα mouse liver cistrome

Project description:Autophagy is an evolutionally conserved catabolic process that recycles nutrients upon starvation and maintains cellular energy homeostasis1-3. Its acute regulation by nutrient sensing signaling pathways is well described, but its longer-term transcriptional regulation is not. The nuclear receptors PPARα and FXR are activated in the fasted or fed liver, respectively4,5. Here we show that both regulate hepatic autophagy. Pharmacologic activation of PPARα reverses the normal suppression of autophagy in the fed state, inducing autophagic lipid degradation, or lipophagy. This response is lost in PPARα knockout (PPARα-/-) mice, which are partially defective in the induction of autophagy by fasting. Pharmacologic activation of the bile acid receptor FXR strongly suppresses the induction of autophagy in the fasting state, and this response is absent in FXR knockout (FXR-/-) mice, which show a partial defect in suppression of hepatic autophagy in the fed state. PPARα and FXR compete for binding to shared sites in autophagic gene promoters, with opposite transcriptional outputs. These results reveal complementary, interlocking mechanisms for regulation of autophagy by nutrient status.

2014-09-27 | GSE61817 | GEO

The class 3 PI3K coordinates autophagy and mitochondrial lipid catabolism by controlling nuclear receptor PPARα

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.

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The nuclear receptors ERRα and PPARα co-ordinately control starvation-induced gene expression in hepatocytes.

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