Effects of glucose sensing/signaling on oxidative stress response in glucose repression mutants of Schizosaccharomyces pombe

Abstract

ABSTRACT. The resistant to glucose repression mutants of Schizosaccharomyces pombe (ird5, ird13, and ird14) have a high tolerance to oxidative stress induced by H 2 O 2 . In all ird mutants, the increased expression level of the fbp1 gene can be interpreted as a lack of glucose repression in these mutants. To investigate the mechanisms of the oxidative stress response in ird mutants, we analyzed the transcription of stress response-related genes, sod1, ctt1, atf1, pap1, and sty1, under stressed and non-stressed conditions. We then analyzed the phosphorylation state of the Sty1-MAP kinase in ird mutants. Our findings support the concept of an adaptive response to oxidative stress in these mutants. In addition, these results imply that either glucose signaling mechanisms leading to glucose repression and glucose utilization as an energy source are regulated apart from each other or, like Saccharomyces cerevisiae, S. pombe might have additional glucose detection systems.

Role of glucose repression in the oxidative stress response ofSchizosaccharomyces pombe: analysis of transcript levels of fbp1, hxk2, sod1and ctt1 genes in sty1, atf1 and pap1 knock-out mutants

“…In previous studies, under oxidative stress conditions, the expressions of tpx1 (encoding thioredoxidase), sod1, and ctt1 were quickly induced in a Pap1-dependent manner (Toone et al, 1998;Mutoh et al, 2002), whereas the expression of gpx1, encoding glutathione peroxidase, was controlled by Atf1 (Toone et al, 1998). In our previous study, the transcript levels of pap1 and sty1 increased in ird5, a strain resistant to glucose repression and oxidative stress, under both stressed and nonstressed conditions (Palabiyik et al, 2013). In the present study, we evaluated the transcript levels of sod1 and ctt1 in double and single mutants and their respective controls.…”

Role of Oxidative Stress Response and Trehalose Accumulation in the Longevity of Fission Yeast

“…We suggest that the longevity of the ird5 mutant grown in both repressed and de-repressed conditions might be, in part, in consequence of glucose depletion condition caused by a reduced glucose consumption rate in these cells compared to the ird11 mutant and the wild type. Because, contrary to ird11 , there is an adaptive response to oxidative stress in ird5 , caused by glucose sensing/signaling which emerges in glucose starvation ( 29 ). In light of the results of the present study, it seems that lifespan extension is mostly related to glucose sensing/signaling rather than oxidative stress response and trehalose accumulation.…”

“…In the ird11 mutant, the oxidative stress response is affected by glucose signaling in a manner different from that caused by glucose deprivation ( 28 ). The ird5 mutant has a lower caloric intake owing to reduced glucose consumption efficiency ( 29 ). The inefficient glucose uptake in ird5 might be a cause of increased oxidative stress response.…”

Multifaceted effects of antimetabolite and anticancer drug, 2‐deoxyglucose on eukaryotic cancer models budding and fission yeast

“…One of the enzyme routinely used for the determination of the status of glucose repression is glucose repressible invertase which is located in the cell wall . Glucose sensing is essential for the regulation of many processes ranging from apparent ones like transcription, metabolism, respiration and others to many seemingly unrelated processes like mRNA stability, stress response, cell integrity and cell cycle regulation .…”

“…The resistance of these mutants to oxidative stress was accompanied by an increased Pap1 and Sty1 expression, however the increase in the expression of Atf1 was only observed in ird‐5 indicating the complexity and dependency of the resistance mechanisms on the type of mutation. The increased expression of fbp1 gene along with the reduced efficiency of glucose consumption by these mutants causes lack of glucose repression .…”