Role of PPAR? and HNF4? in stress-mediated alterations in lipid homeostasis.
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ABSTRACT: Stress is a risk factor for several cardiovascular pathologies. PPAR? holds a fundamental role in control of lipid homeostasis by directly regulating genes involved in fatty acid transport and oxidation. Importantly, PPAR? agonists are effective in raising HDL-cholesterol and lowering triglycerides, properties that reduce the risk for cardiovascular diseases. This study investigated the role of stress and adrenergic receptor (AR)-related pathways in PPAR? and HNF4? regulation and signaling in mice following repeated restraint stress or treatment with AR-antagonists administered prior to stress to block AR-linked pathways. Repeated restraint stress up-regulated Ppar? and its target genes in the liver, including Acox, Acot1, Acot4, Cyp4a10, Cyp4a14 and Lipin2, an effect that was highly correlated with Hnf4?. In vitro studies using primary hepatocyte cultures treated with epinephrine or AR-agonists confirmed that hepatic AR/cAMP/PKA/CREB- and JNK-linked pathways are involved in PPAR? and HNF4? regulation. Notably, restraint stress, independent of PPAR?, suppressed plasma triglyceride levels. This stress-induced effect could be attributed in part to hormone sensitive lipase activation in the white adipose tissue, which was not prevented by the increased levels of perilipin. Overall, this study identifies a mechanistic basis for the modification of lipid homeostasis following stress and potentially indicates novel roles for PPAR? and HNF4? in stress-induced lipid metabolism.
SUBMITTER: Konstandi M
PROVIDER: S-EPMC3743822 | biostudies-literature | 2013
REPOSITORIES: biostudies-literature
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