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Hypothalamic PGC-1? protects against high-fat diet exposure by regulating ER?.

ABSTRACT: High-fat diets (HFDs) lead to obesity and inflammation in the central nervous system (CNS). Estrogens and estrogen receptor ? (ER?) protect premenopausal females from the metabolic complications of inflammation and obesity-related disease. Here, we demonstrate that hypothalamic PGC-1? regulates ER? and inflammation in vivo. HFD significantly increased palmitic acid (PA) and sphingolipids in the CNS of male mice when compared to female mice. PA, in vitro, and HFD, in vivo, reduced PGC-1? and ER? in hypothalamic neurons and astrocytes of male mice and promoted inflammation. PGC-1? depletion with ER? overexpression significantly inhibited PA-induced inflammation, confirming that ER? is a critical determinant of the anti-inflammatory response. Physiologic relevance of ER?-regulated inflammation was demonstrated by reduced myocardial function in male, but not female, mice following chronic HFD exposure. Our findings show that HFD/PA reduces PGC-1? and ER?, promoting inflammation and decrements in myocardial function in a sex-specific way.

SUBMITTER: Morselli E

PROVIDER: S-EPMC4223650 | biostudies-literature | 2014 Oct

REPOSITORIES: biostudies-literature

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Hypothalamic PGC-1α protects against high-fat diet exposure by regulating ERα.

Morselli Eugenia E Fuente-Martin Esther E Finan Brian B Kim Min M Frank Aaron A Garcia-Caceres Cristina C Navas Carlos Rodriguez CR Gordillo Ruth R Neinast Michael M Kalainayakan Sarada P SP Li Dan L DL Gao Yuanqing Y Yi Chun-Xia CX Hahner Lisa L Palmer Biff F BF Tschöp Matthias H MH Clegg Deborah J DJ

Cell reports 20141016 2

High-fat diets (HFDs) lead to obesity and inflammation in the central nervous system (CNS). Estrogens and estrogen receptor α (ERα) protect premenopausal females from the metabolic complications of inflammation and obesity-related disease. Here, we demonstrate that hypothalamic PGC-1α regulates ERα and inflammation in vivo. HFD significantly increased palmitic acid (PA) and sphingolipids in the CNS of male mice when compared to female mice. PA, in vitro, and HFD, in vivo, reduced PGC-1α and ERα ...[more]

PMID: 25373903

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Project description:BackgroundNeuroinflammation and immune responses occurring minutes to hours after stroke are associated with brain injury after acute ischemic stroke (AIS). PPARγ coactivator-1α (PGC-1α), as a master coregulator of gene expression in mitochondrial biogenesis, was found to be transiently upregulated in microglia after AIS. However, the role of microglial PGC-1α in poststroke immune modulation remains unknown.MethodsPGC-1α expression in microglia from human and mouse brain samples following ischemic stroke was first determined. Subsequently, we employed transgenic mice with microglia-specific overexpression of PGC-1α for middle cerebral artery occlusion (MCAO). The morphology and gene expression profile of microglia with PGC-1α overexpression were evaluated. Downstream inflammatory cytokine production and NLRP3 activation were also determined. ChIP-Seq analysis was performed to detect PGC-1α-binding sites in microglia. Autophagic and mitophagic activity was further monitored by immunofluorescence staining. Unc-51-like autophagy activating kinase 1 (ULK1) expression was evaluated under the PGC-1α interaction with ERRα. Finally, pharmacological inhibition and genomic knockdown of ULK1 were performed to estimate the role of ULK1 in mediating mitophagic activity after ischemic stroke.ResultsPGC-1α expression was shortly increased after ischemic stroke, not only in human brain samples but also in mouse brain samples. Microglia-specific PGC-1α overexpressing mice exhibited significantly decreased neurologic deficits after ischemic injury, with reduced NLRP3 activation and proinflammatory cytokine production. ChIP-Seq analysis and KEGG pathway analysis revealed that mitophagy was significantly enhanced. PGC-1α significantly promoted autophagic flux and induced autolysosome formation. More specifically, the autophagic clearance of mitochondria was enhanced by PGC-1α regulation, indicating the important role of mitophagy. Pharmacological inhibition or knockdown of ULK1 expression impaired autophagic/mitophagic activity, thus abolishing the neuroprotective effects of PGC-1α.ConclusionsMechanistically, in AIS, PGC-1α promotes autophagy and mitophagy through ULK1 and reduces NLRP3 activation. Our findings indicate that microglial PGC-1α may be a promising therapeutic target for AIS.

Project description:Background/Aims:Increasing evidence have associated mitochondrial dysfunction and reactive oxygen species (ROS) generation to neuron loss in multiple sclerosis (MS). PGC-1α regulates mitochondrial biogenesis and respiration and plays a pivotal role in modulating ROS levels. Here, we investigated the potential function of peroxisome proliferator-activated receptor-γ co-activator-1α (PGC-1α) in the mammalian MS disease model, EAE experimental autoimmune encephalomyelitis (EAE). Methods:We used WT mice to evaluate the change of PGC during the course of EAE. The transgenic mice with neuron-specific overexpression of PGC-1α was applied to explore how PGC1 in neuron affects EAE outcome. A neuronal cell line of lentivirus transfection leading to PGC-1α markedly increased was applied to verify the protective effects of PGC1 in neurons. RNA-seq was employed to explore the potential target genes and signaling pathways. Results: We observed that PGC-1α were decreased at 13d, continuously decreased at 20d, then mildly increased at 30d in wild-type (WT) EAE mice, which is accompanied with alterations of mitochondrial antioxidants SOD2, Prx3, Trx2 and UCP4,5. Our study revealed that PGC-1αf/f Eno2-Cre mice improved EAE clinical symptoms, ameliorated inflammation and demyelination in spinal cords, increased mitochondrial antioxidants SOD2, Prx3, Trx2 and UCPs, reduced the production of ROS and inhibited the apoptotic pathways. In addition, PGC-1αf/f Eno2-Cre mice showed decreased apoptotic neurons compared with the WT EAE mice. In vitro, overexpressing PGC-1α by lentivirus transfection revealed similar results with that of in vivo by using NSC-34 cells treated with 1mg/ml lipopolysaccharide (LPS). Furthermore, RNA-seq analysis showed that apoptotic processes were significantly enriched in the top 10 significant GO terms of differentially expressed (DE) gene and apotosis pathway was significantly enriched in KEGG pathway analysis. Conclusion: Taken together, our findings indicate that upregulation of neuronal PGC-1α protected neuron apotosis in EAE and in vitro.

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Hypothalamic PGC-1? protects against high-fat diet exposure by regulating ER?.

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Hypothalamic PGC-1α protects against high-fat diet exposure by regulating ERα.

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