Project description:Identification of QTL for chronological lifespan. Pools of non-dividing, intercrossed fission yeast were sampled through time to identify alleles enriched in long-lived cells.
Project description:An increasing number of studies have shown that the promising compound resveratrol treats multiple diseases, such as cancer and aging; however, the resveratrol mode-of-action (MoA) remains largely unknown. Here, by virtue of multiple omics approaches, we adopted fission yeast as a model system with the goal of dissecting the common MoA of the anti-proliferative activity of resveratrol. Fission yeast was chosen as the model because of the following reasons: fission yeast is a terrific model to investigate the cell cycle and cell shape; the yeast belongs to the âCrabtree Positiveâ yeast kingdom, which possesses features similar to the âWarburg Effectâ of cancer cells such that the fission yeast prefers to conduct fermentation with glucose as the carbon source for energy production ; many omics tools and datasets are available for the systematic exploration of the drugâs effects at different concentration. This experiment uses microarray analysis with the aim of exploring transcriptional modulation after natural product resveratrol treatment at the IC50 drug concentration, in fission yeast S.pombe.
Project description:Saccharomyces cerevisiae is currently widely used as a model to study chronological aging of metazoan cells. Chronological aging is typically studied in aerobic stationary phase (SP) cultures, i.e. the final stage of batch cultures in which growth is arrested due to exogenous carbon source exhaustion. Survival of yeast cells in SP defines their chronological lifespan (CLS). S. cerevisiae SP cultures have strongly contributed to the understanding of cellular mechanisms involved in aging and indicated a key role for oxygen. Oxygen is the natural starting point for reactive oxygen species (ROS) that may both have malignant and beneficial effects on aging. In addition, oxygen allows yeast to grow on ethanol and organic acids formed during the initial respiro-fermentative growth phase on glucose. This post-diauxic phase is hallmarked by reduced growth rates, increased expression of genes involved in SP survival, and increased stress resistance. To date, the role of oxygen and respiration in aging has mostly been studied using respiratory deficient mutants, and respiration repressing agents. However, genetic or chemical interventions may result in unwanted side effects that influence survival in SP. We therefore followed a different approach to evaluate the impact of oxygen availability on yeast robustness in SP, i.e. its CLS and stress resistance, by using the capability of S. cerevisiae to grow under anaerobic conditions. A thorough physiological comparison of strictly anaerobic and aerobic SP cultures revealed that the presence of oxygen during growth and aging of S. cerevisiae strongly affects its energetic status, longevity and stress tolerance in a positive way. Combining the physiological data with genome-wide expression analysis revealed that the oxygen-dependent diauxic growth phase enabled the full induction of robustness in S. cerevisiae, and points to appropriate pre-conditioning of cells as a crucial factor to survive starvation. These findings highlight the importance of exogenous energy availability in the conditions leading to growth arrest, and bring new insight on the role of oxygen in the aging of eukaryotes. The goal of the present study is to evaluate the impact of oxygen availability on yeast longevity. More specifically, the questions addressed are whether the presence of a â??conditioningâ?? post-diauxic phase and the ability to utilize efficiently reserves, characteristics of aerobicity, affects yeast survival during stationary phase. To this end, S. cerevisiae was cultivated in well controlled bioreactors under the presence or absence of oxygen. S. cerevisiaeâ??s response to oxygen availability was monitored by an in-depth physiological analysis combined with genome wide expression analysis.
Project description:Caloric restriction (CR) is the only non-genetic intervention to retard aging and increase longevity in a variety of species. It is important to understand the fundamental mechanism by which CR extends lifespan that remains elusive. Owing to well-established genomic tools and convenience of culture system, we used a single cell organism, Saccharomyces cerevisiae, to clarify the mechanisms of CR. In order to identify genes responsible for CR-mediated longevity, we performed microarray experiments across the longevity assurance time-points. Since the CR-treated cells obtained the longevity potential around 12 hours after inoculation and the strength of potential gradually increased up to 48 hours, we concluded that the changes across these time-points must be a critical need for assurance of longevity by CR. For preparation of total RNA, yeast cells under control (2% glucose) and CR (0.5% glucose) conditions were harvested at 12h, 18h, 24h and 48h after inoculation. After total RNA extraction, we performed Affymetrix Yeast GeneChip 2.0 array for biological triplicate repeats according to the manufacturer's instructions.
Project description:Extending lifespan from yeast to mammals, calorie restriction (CR) is the most conserved longevity intervention. Numerous conserved pathways regulating aging and mediating CR have been identified; however, the overall proteomic changes during these conditions remain largely unexplored. We compared proteomes between young and replicatively aged yeast cells under normal and CR conditions using SILAC quantitative proteomics and discovered distinct signatures in the aging proteome. We found remarkable similarities between aged and CR cells, including induction of stress response pathways, providing evidence that CR pathways are engaged in aged cells. These observations also uncovered aberrant changes in mitochondria membrane proteins as well as a proteolytic cellular state in old cells. These proteomics analyses also help identify potential genes and pathways that have causal effects on longevity.
Project description:Target of rapamycin complex 1 (TORC1) is implicated in growth control and aging from yeast to humans. Fission yeast is emerging as a popular model organism to study TOR signaling, although rapamycin has been thought to not affect cell growth in this organism. Here we analyzed the effects of rapamycin and caffeine, singly and combined, on multiple cellular processes in fission yeast. The two drugs led to diverse and specific phenotypes that depended on TORC1 signaling pathway inhibition, including prolonged chronological lifespan, inhibition of global translation, inhibition of cell growth and division, and reprogramming of global gene expression mimicking nitrogen starvation. Rapamycin and caffeine differentially affected these various TORC1-dependent processes. Combined drug treatment augmented most phenotypes and effectively blocked cell growth. Although rapamycin showed a much more subtle effect on global translation than did caffeine, rapamycin was more effective in prolonging chronological lifespan. Rapamycin prolonged the lifespan of non-growing cells only when applied during the growth phase but not when applied after cells had stopped proliferation. The doses of rapamycin and caffeine strongly correlated with growth inhibition and with lifespan extension. This comprehensive analysis will inform future studies into TORC1 function and cellular aging in fission yeast and beyond.
Project description:mTOR is a conserved proaging pathway with characterised inhibitors like rapamycin and torins. A third-generation inhibitor, rapalink-1, has been developed, however, its effects on organismal gene expression and lifespan have not been evaluated. Here, we demonstrate that rapalink-1 affects fission yeast spatial and temporal growth and prolongs chronological lifespan. Endosome and vesicle-mediated transport and homeostasis processes related to autophagy and Pik3, the orthologue of human PI3K, render cells resistant to rapalink-1. Our study reveals mTOR-regulated genes with unknown roles in aging including all fission yeast agmatinases, the enzymes responsible for processing agmatine to putrescine and urea. We identify sensitive and resistant mutants to agmatine and putrescine and show that all fission yeast agmatinase enzymes are required for normal lifespan. Genetic interactome assays for the agmatinase agm1 and further analyses demonstrate that impairing the agmatinergic branch of arginine catabolism results in mTOR activity levels that are beneficial for growth but detrimental for chronological aging. Our study reveals metabolic circuits with possible implications to other systems, including human cells.
Project description:Genomic instability associated with DNA replication stress is linked to cancer and genetic pathologies in humans. If not properly regulated, replication stress, such as fork stalling and collapse, can be induced at natural replication impediments present throughout the genome. The fork protection complex (FPC) is thought to play a critical role in stabilizing stalled replication forks at several known replication barriers including eukaryotic rDNA genes and the fission yeast mating-type locus. However, little is known about the role of the FPC at other natural impediments including telomeres. Telomeres are considered to be difficult to replicate due to the presence of repetitive GT-rich sequences and telomere-binding proteins. However, the regulatory mechanism that ensures telomere replication is not fully understood. Here, we report the role of the fission yeast Swi1/Timeless, a subunit of the FPC, in telomere replication. Loss of Swi1 causes telomere shortening in a telomerase-independent manner. Our epistasis analyses suggest that heterochromatin and telomere-binding proteins are not major impediments for telomere replication in the absence of Swi1. Instead, repetitive DNA sequences impair telomere integrity in swi1Î mutant cells, leading to the loss of repeat DNA. In the absence of Swi1, telomere shortening is accompanied with an increased recruitment of Rad52 recombinase and more frequent amplification of telomere/subtelomeres, reminiscent of tumor cells that utilize the alternative lengthening of telomeres pathway (ALT) to maintain telomeres. These results suggest that Swi1 ensures telomere replication by suppressing recombination and repeat instability at telomeres. Our studies may also be relevant in understanding the potential role of the FPC in regulation of telomere stability in cancer cells. Genome-wide distributions of Rad52 in wild type and in swi1 deletion in fission yeast The'SP1173_WT ChIP-seq' is an input sample (non-tagged data).
Project description:Occupancy profiling of lysine 9 dimethylated histone H3 in fission yeast. Occupancy profiling of MYC-tagged or GFP-tagged Pir1 protein in fission yeast. Occupancy profiling of FLAG-tagged Rec12-DNA linkages during meiosis of fission yeast.