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TOR1-Mediated Control of Lifespan Genes: Insights from Saccharomyces cerevisiae

ABSTRACT: This study investigated the effects of TOR1 gene deletion on Saccharomyces cerevisiae through transcriptome analysis of wild-type and tor1Δ mutant cells during exponential development under non-stress circumstances. A significant number of differentially expressed genes (DEGs) were identified in the absence of TOR1, comprising 1665 upregulated genes and 1425 downregulated genes. These findings demonstrate the extensive impact of TOR signaling on several biological processes, including metabolism, stress response, and lifespan regulation. A significant number of differentially expressed genes (DEGs) were identified in the absence of TOR1, comprising 1665 upregulated genes and 1425 downregulated genes. These findings demonstrate the extensive impact of TOR signaling on several biological processes, including metabolism, stress response, and lifespan regulation. A total of 736 DEGs were associated with either replicative lifespan or chronological lifespan, further emphasizing the significance of TOR1 in aging. Although genes associated with glucose transporters and storage were upregulated, glycolytic genes remained unchanged, indicating a metabolic shift towards alternative pathways such as gluconeogenesis and the pentose phosphate pathway. Among these, HXK1 exhibited the highest upregulation in tor1Δ cells, contrasting with HXK2, whose expression remained stable. This suggests that HXK1, typically active under low glucose or caloric restriction, plays a crucial role in reregulating glucose metabolism in the absence of TOR1. The research also identified specific transcription factors, including ADR1, HAP4, and their paralogs, which were upregulated and bound only to the HXK1 promoter, pointing to their regulatory role in this metabolic shift. The findings indicate that TOR1 inactivation triggers nutrient- and energy-sensing mechanisms that redirect cellular resources towards stress adaptation and longevity, highlighting Tor1's crucial function in aging and proposing that modulation of the TOR pathway could be a potential strategy for anti-aging therapies.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE280426 | GEO | 2025/10/01

REPOSITORIES: GEO

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Project description:The target of rapamycin (TOR) pathway is an evolutionarily conserved signal transduction system that is activated by varying nutrient and environmental signals and governs a plethora of eukaryotic biological processes, but its role in Cryptococcus neoformans remains elusive. In this study, we investigated the TOR pathway by functionally characterizing two Tor-like kinases, Tor1 and Tlk1, in C. neoformans. We successfully deleted TLK1, but not TOR1. TLK1 deletion did not result in any evident in vitro phenotypes, suggesting that Tlk1 is mainly dispensable for the growth of C. neoformans. We further demonstrated that Tor1, but not Tlk1, is essential and the target of rapamycin by constructing and analyzing conditionally regulated strains and sporulation analysis of heterozygous mutants in the diploid strain background. To analyze the functions of Tor1 in more detail, we constructed constitutive TOR1 overexpression strains. Tor1 negatively regulated thermotolerance and the DNA damage response, which are two important virulence factors of C. neoformans. We also found that TOR1 overexpression reduced Mpk1 phosphorylation, which is required for cell wall integrity and thermoresistance, and Rad53 phosphorylation, which governs the DNA damage response pathway. Tor1 is localized to the cytoplasm but enriched in the vacuole membrane. Phosphoproteomics and transcriptomics revealed that Tor1 regulates a variety of biological processes, including metabolic processes, cytoskeleton organization, ribosome biogenesis, autophagy, and stress response. TOR inhibition by rapamycin caused actin depolarization in a Tor1-dependent manner. Finally, screening rapamycin-sensitive and -resistant kinase and transcription factor mutants revealed that the TOR pathway may crosstalk with a number of signaling pathways, including the Hog1 pathway. In conclusion, our study demonstrates that a single Tor1 kinase plays a variety of roles in the fungal meningitis pathogen C. neoformans.

Project description:The target of rapamycin (TOR) pathway is an evolutionarily conserved signal transduction system that is activated by varying nutrient and environmental signals and governs a plethora of eukaryotic biological processes. Nevertheless, its role in the human fungal pathogen Cryptococcus neoformans remains elusive. In this study, we investigated the TOR pathway by functionally characterizing two Tor-like kinases, Tor1 and Tlk1, in C. neoformans. We successfully deleted TLK1, but not TOR1. TLK1 deletion did not result in any evident in vitro phenotypes, except for a minor role in diamide and polyene resistance, suggesting that Tlk1 is mainly dispensable for the growth of C. neoformans. We further demonstrated that Tor1, but not Tlk1, is essential and the target of rapamycin by constructing and analyzing conditionally regulated strains and sporulation analysis of heterozygous mutants in the diploid strain background. To analyze the functions of Tor1 in more detail, we constructed constitutive TOR1 overexpression strains. Tor1 negatively regulated thermotolerance and the DNA damage response, which are two important virulence factors of C. neoformans. We also found that TOR1 overexpression reduced Mpk1 phosphorylation, which is required for cell wall integrity and thermoresistance, and Rad53 phosphorylation, which governs the DNA damage response pathway. Tor1 is localized to the cytoplasm but enriched in the vacuole membrane. Phosphoproteomics and transcriptomics revealed that Tor1 regulates a variety of biological processes, including metabolic processes, cytoskeleton organization, ribosome biogenesis, autophagy, and stress response. Finally, screening rapamycin-sensitive and -resistant kinase and transcription factor mutants revealed that the TOR pathway may crosstalk with a number of signaling pathways, including the Hog1 pathway. In conclusion, our study demonstrates that a single Tor1 kinase plays a variety of roles in the fungal meningitis pathogen C. neoformans.

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.

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TOR1-Mediated Control of Lifespan Genes: Insights from Saccharomyces cerevisiae

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