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Calorie Restriction Feminizes Liver Gene Expression and Alters Key Regulators of Conserved Aging Regulatory Pathways

ABSTRACT: Background: Calorie restriction (CR) is the only intervention known to extend lifespan in a wide range of organisms, including mammals. However, the mechanisms by which it regulates mammalian aging remain largely unknown and the involvement of the TOR and Sirtuin pathways (which regulate aging in lower organisms) remain controversial. Femaleness is a second phenotype generally associated with longevity but the relationship between sex-biased and CR-induced gene expression remains undetermined. Methodology/Principal Findings: We generated microarray gene expression data from livers of male mice fed high calorie or CR diets, and we find that CR significantly changes the expression of over 3,000 genes, many between 10- and 50-fold. We compare our data to the GenAge database of known aging-related genes and to prior microarray expression data of genes expressed differently between male and female mice. CR generally feminizes gene expression and many of the most significantly changed individual genes are involved in aging, hormone signaling, and p53-associated regulation of the cell cycle and apoptosis. Among the genes showing the largest and most statistically significant CR-induced expression differences are Ddit4, a key regulator of the TOR pathway, and Nnmt, a regulator of lifespan linked to the Sirtuin pathway. Using Western analyses, we confirmed post-translational inhibition of the TOR pathway. Conclusions: Our data show that CR induces widespread gene expression changes and acts through highly evolutionarily conserved pathways, from microorganisms to mammals, and that its life-extension effects might arise partly from a shift toward a gene expression profile more typical of the longer-lived female sex. Keywords: Two-class gene expression comparison. Calorie restriction (CR) versus HIGH CALORIE feeding.

ORGANISM(S): Mus musculus

PROVIDER: GSE11244 | GEO | 2008/12/31

SECONDARY ACCESSION(S): PRJNA106749

REPOSITORIES: GEO

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Project description:Background: Calorie restriction (CR) is the only intervention known to extend lifespan in a wide range of organisms, including mammals. However, the mechanisms by which it regulates mammalian aging remain largely unknown and the involvement of the TOR and Sirtuin pathways (which regulate aging in lower organisms) remain controversial. Femaleness is a second phenotype generally associated with longevity but the relationship between sex-biased and CR-induced gene expression remains undetermined. Methodology/Principal Findings: We generated microarray gene expression data from livers of male mice fed high calorie or CR diets, and we find that CR significantly changes the expression of over 3,000 genes, many between 10- and 50-fold. We compare our data to the GenAge database of known aging-related genes and to prior microarray expression data of genes expressed differently between male and female mice. CR generally feminizes gene expression and many of the most significantly changed individual genes are involved in aging, hormone signaling, and p53-associated regulation of the cell cycle and apoptosis. Among the genes showing the largest and most statistically significant CR-induced expression differences are Ddit4, a key regulator of the TOR pathway, and Nnmt, a regulator of lifespan linked to the Sirtuin pathway. Using Western analyses, we confirmed post-translational inhibition of the TOR pathway. Conclusions: Our data show that CR induces widespread gene expression changes and acts through highly evolutionarily conserved pathways, from microorganisms to mammals, and that its life-extension effects might arise partly from a shift toward a gene expression profile more typical of the longer-lived female sex. Keywords: Two-class gene expression comparison. Calorie restriction (CR) versus HIGH CALORIE feeding. Design of the experiment is a two-class paired design in which the two classes are HIGH CALORIE and CALORIE RESTRICTION (CR) dietary regimens fed to mice, resulting in 15 HIGH CALORIE microarrays and 8 CR microarrays; 23 total microarrays. Four HIGH CALORIE and 2 CR microarrays were produced using pools of 3 RNA samples for each microarray (6 pools of 3, plus 17 individual samples = 35 individual mouse liver samples, 23 microarrays). Total liver RNA was labeled directly. Reference RNA: Stratagene Universal Mouse Reference RNA.

Project description:The chronological lifespan (CLS) of Saccharomyces cerevisiae is defined as the number days that non-dividing cells remain viable, typically in stationary phase cultures or in water. CLS is extended by restricting glucose in the starting cultures, and is considered a form of caloric restriction (CR). Through a previous genetic screen our lab determined that deleting components of the de novo purine biosynthesis pathway also significantly increased CLS. Significant similarities in gene expression profiles between calorie restricted WT cells and a non-restricted ade4M-bM-^HM-^F mutant suggested the possibility of common gene expression biomarkers of all chronologically long lived cells that could also provide insights into general mechanisms of lifespan extension. We have identified additional growth conditions that extend CLS of WT cells, including supplementation of the media with isonicotinamide (INAM), a known sirtuin activator, or by supplementation with a concentrate collected from the expired media of a calorie restricted yeast culture, presumably due to an as yet unidentified longevity factor. Using these varied methods to extend CLS, we compared gene expression profiles in the aging cells (at day 8) to identify functionally relevant biomarkers of longevity. Nineteen genes were differentially regulated in all 4 of the long-lived populations relative to wild type. Of these 19 genes, viable haploid deletion mutants were available for 16 of them, and 12 were found to have a significant impact on CLS. Duplicate cultures were grown to saturation in SC media cultures, aged, and then harvested on day 8. The deletion mutant ade4M-bM-^HM-^F as well as WT cells treated with 25 mM isonicotinamide, calorie restricted (0.5% glucose), or treated with expired media concentrate from previously calorie restricted cultures. These 4 conditions were then compared to a wild-type (WT) strain. Total RNA was isolated and used for microarray hybridizations onto Affymetrix Yeast 2.0 Gene arrrays.

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Calorie Restriction Feminizes Liver Gene Expression and Alters Key Regulators of Conserved Aging Regulatory Pathways

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