Project description:This study utilized AgRP+/- and AgRP-/- mice either under fed or 30h fasted conditions, to reveal genes that are regulated by fasting and AgRP.
Project description:The hypothalamus is a key site for the integration of the response to nutrient deprivation in higher organisms. Transcripts that are dynamically regulated in the hypothalamus by feeding and fasting are likely to play a regulatory role in energy balance. In order to identify hypothalamic genes whose expression is altered by fasting, we compared the transcriptomes of hypothalamic blocks from freely feeding vs overnight fasted mice using whole genome oligonucleotide arrays. In order to exclude changes due to non-specific neuronal stress responses to energy deprivation we simultaneously profiled the cerebellum, a brain site with no known regulatory role in energy balance. The power of this approach was illustrated by the fact that while we confirmed previous observations that the Sulfotransferase family 1A gene is upregulated by fasting in the hypothalamus, we showed that it was similarly upregulated in the cerebellum and is therefore unlikely to be specifically involved in the regulation of energy balance. In contrast, using three different methods of pathway enrichment analysis, multiple genes involved in mitochondrial oxidative phosphorylation were found to be co-ordinately downregulated by fasting in the hypothalamus but not in the cerebellum. These findings suggest that a switch from oxidative to non-oxidative metabolism in the hypothalamus may be an important element of the homeostatic response to nutrient deprivation. Keywords: hypothalamus, cerebellum, fasting, appetite, obesity
Project description:Dietary restriction extends lifespan and delays the age-related physiological decline in many species. Intermittent fasting (IF) is one of the most effective dietary restriction regimens that extends lifespan in C. elegans and mammals1,2. In C. elegans, the FOXO transcription factor DAF-16 is implicated in fasting-induced gene expression changes and the longevity response to IF3; however, the mechanisms that sense and transduce fasting-stress stimuli have remained largely unknown. Here we show that a KGB-1/AP1 (activator protein 1) module is a key signalling pathway that mediates fasting-induced transcriptional changes and IF-induced longevity. Our promoter analysis coupled to genome-wide microarray results has shown that the AP-1-binding site, together with the FOXO-binding site, is highly over-represented in the promoter regions of fasting-induced genes. We find that JUN-1 (C. elegans c-Jun) and FOS-1 (C. elegans c-Fos), which constitute the AP-1 transcription factor complex, are required for IF-induced longevity. We also find that KGB-1 acts as a direct activator of JUN-1 and FOS-1, is activated in response to fasting, and, among the three C. elegans JNKs, is specifically required for IF-induced longevity. Our results demonstrate that most fasting-induced upregulated genes, including almost all of the DAF-16-dependent genes, require KGB-1 and JUN-1 function for their induction, and that the loss of kgb-1 suppresses the fasting-induced upregulation of DAF-16 target genes without affecting fasting-induced DAF-16 nuclear translocation. These findings identify the evolutionarily conserved JNK/AP-1 module as a key mediator of fasting-stress responses, and suggest a model in which two fasting-induced signalling pathways leading to DAF-16 nuclear translocation and KGB-1/AP-1 activation, respectively, integrate in the nucleus to coordinately mediate fasting-induced transcriptional changes and IF-induced longevity. To delineate the whole picture of transcriptional changes in response to fasting, we performed genome-wide gene expression analyses during 2 days (48 h) fasting. Two and three independent experiments were performed in the time course and mutants, respectively.
Project description:Dietary restriction extends lifespan and delays the age-related physiological decline in many species. Intermittent fasting (IF) is one of the most effective dietary restriction regimens that extends lifespan in C. elegans and mammals1,2. In C. elegans, the FOXO transcription factor DAF-16 is implicated in fasting-induced gene expression changes and the longevity response to IF3; however, the mechanisms that sense and transduce fasting-stress stimuli have remained largely unknown. Here we show that a KGB-1/AP1 (activator protein 1) module is a key signalling pathway that mediates fasting-induced transcriptional changes and IF-induced longevity. Our promoter analysis coupled to genome-wide microarray results has shown that the AP-1-binding site, together with the FOXO-binding site, is highly over-represented in the promoter regions of fasting-induced genes. We find that JUN-1 (C. elegans c-Jun) and FOS-1 (C. elegans c-Fos), which constitute the AP-1 transcription factor complex, are required for IF-induced longevity. We also find that KGB-1 acts as a direct activator of JUN-1 and FOS-1, is activated in response to fasting, and, among the three C. elegans JNKs, is specifically required for IF-induced longevity. Our results demonstrate that most fasting-induced upregulated genes, including almost all of the DAF-16-dependent genes, require KGB-1 and JUN-1 function for their induction, and that the loss of kgb-1 suppresses the fasting-induced upregulation of DAF-16 target genes without affecting fasting-induced DAF-16 nuclear translocation. These findings identify the evolutionarily conserved JNK/AP-1 module as a key mediator of fasting-stress responses, and suggest a model in which two fasting-induced signalling pathways leading to DAF-16 nuclear translocation and KGB-1/AP-1 activation, respectively, integrate in the nucleus to coordinately mediate fasting-induced transcriptional changes and IF-induced longevity. To delineate the whole picture of transcriptional changes in response to fasting, we performed genome-wide gene expression analyses during 2 days (48 h) fasting.
Project description:We used Methyl-MiniSeq platform from Zymo Research company to identify genome-wide methylation changes affected by overnight fasting in mice liver. Compared to control mice liver, we observed extensive genome-wide methylation patern changes in fasted mice liver, with some genes showing incresed methylation, others showing decreased methylation, and the rest with no significant change.
Project description:Analysis of fasting-induced change of metabolites in mice confirmed that glucose level was reduced in the liver, but unaffected in the brain of fasted mice. To explore molecular mechanisms for the preferential glucose supply to the brain upon fasting, we compared gene expression profiles of the brain between fasted and fed mice. Gene ontology (GO) term analysis revealed the enrichment of one GO term, “active membrane transporters activity”. We also showed that fasting enhances the expression of a glucose transporter Slc2a1 (Glut1) gene.
Project description:Mammalian energy homeostasis is regulated by the hypothalamus and hindbrain, with the hippocampus, midbrain nuclei, and other regions implicated by evidence from human genetics studies. In order to understand how these brain regions respond to imbalances in energy homeostasis, we performed two experiments examining the effects of different diets in male C57BL6 mice. In our first study, groups of 6 pair-housed mice were given access to chow, high-fat diet or fasted for 16 hours. In our subsequent study, two groups of 10 mice were single-housed and given access to chow or fasted for 24h. We recorded food intake for each cage, the change in body weight for each animal, and collected hypothalamus, hippocampus, superior colliculus, inferior colliculus, prefrontal cortex, and zona incerta samples. We performed bulk RNA sequencing on 185 samples and validated them by a series of quality control assessments including alignment quality and gene expression profiling. We believe these studies capture the transcriptomic effects of acute fasting and high fat diet in the rodent brain and provide a valuable reference.