Nuclear cholesterol regulates nuclear size and DNA damage responses in the tumor hierarchy
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ABSTRACT:
PROVIDER: PRJNA1035086 | ENA |
REPOSITORIES: ENA
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Project description:Cholesterol has attracted significant attention as a possible lifespan regulator. It has been reported that serum cholesterol levels have an impact on mortality due to age-related disorders such as cardiovascular disease. Diet is also known to be an important lifespan regulator. Dietary restriction retards the onset of age-related diseases and extends lifespan in various organisms. Although cholesterol and dietary restriction are known to be lifespan regulators, it remains to be established whether cholesterol is involved in dietary restriction-induced longevity. Here, we show that cholesterol deprivation suppresses longevity induced by intermittent fasting, which is one of the dietary restriction regimens that effectively extend lifespan. We also found that cholesterol is required for the fasting-induced upregulation of transcriptional target genes such as the insulin/IGF-1 pathway effector DAF-16 and that cholesterol deprivation suppresses the long lifespan of the insulin/IGF-1 receptor daf-2 mutant. Remarkably, we found that cholesterol plays an important role in the fasting-induced nuclear accumulation of DAF-16. Moreover, knockdown of the cholesterol-binding protein NSBP-1, which has been shown to bind to DAF-16 in a cholesterol-dependent manner and to regulate DAF-16 activity, suppresses both fasting-induced longevity and DAF-16 nuclear accumulation. Furthermore, this suppression was not additive to the cholesterol deprivation-induced suppression, which suggests that NSBP-1 mediates, at least in part, the action of cholesterol to promote fasting-induced longevity and DAF-16 nuclear accumulation. These findings identify a novel role for cholesterol in the regulation of lifespan. Two independent replicates were performed. Total RNA was extracted with TRIzol (Invitrogen). The extracted RNA was purified with PureLink RNA Micro Kit (Invitrogen) and analyzed with Agilent 2100 Bioanalyzer to assess the RNA integrity. The microarray procedures were performed according to Affymetrix protocols. Hybridized arrays were scanned using an Affymetrix GeneChip Scanner.
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Project description:TCPOBOP (1,4-bis[2-(3,5-dichloropyridyloxy)]benzene) and PCN (pregnenolone 16α-carbonitrile) are inducers of drug metabolism through activation of nuclear receptors CAR (constitutive androstane receptor) and PXR (pregnane X receptor), respectively. Mouse experiment was designed to study the effect of CAR and PXR activation on cholesterol homeostasis genes and other genes, which are present on the Steroltalk v2 microarray. Treatments were combined with standard and high-cholesterol diet to observe the interference of high liver cholesterol on nuclear receptor transcription regulation. All experiments were done within the European sixth Framework program âSteroltalkâ (www.steroltalk.net). Results form these experiments give new knowledge about involvement of âxenosensorsâ CAR and PXR in regulation of endogenous liver metabolism. Animals were injected i.p. 3mg/kg TCPOBOP, 40 mg/kg PCN or vehicle (corn oil) in combination of one week of standard or 1% cholesterol diet prior tretament. After 24h they were sacrificed and total RNA was isolated from the livers. Each sample was hybridized with a reference sample to Steroltalk v2 microarrays.
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