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A genome-wide screen for FTY720-sensitive mutants reveals genes required for ROS homeostasis.

ABSTRACT: Fingolimod hydrochloride (FTY720), a sphingosine-1-phosphate (S1P) analogue, is an approved immune modulator for the treatment of multiple sclerosis (MS). Notably, in addition to its well-known mode of action as an S1P modulator, accumulating evidence suggests that FTY720 induces apoptosis in various cancer cells via reactive oxygen species (ROS) generation. Although the involvement of multiple signaling molecules, such as JNK (Jun N-terminal kinase), Akt (alpha serine/threonine-protein kinase) and Sphk has been reported, the exact mechanisms how FTY720 induces cell growth inhibition and the functional relationship between FTY720 and these signaling pathways remain elusive. Our previous reports using the fission yeast Schizosaccharomyces pombe as a model system to elucidate FTY720-mediated signaling pathways revealed that FTY720 induces an increase in intracellular Ca2+ concentrations and ROS generation, which resulted in the activation of the transcriptional responses downstream of Ca2+/calcineurin signaling and stress-activated MAPK signaling, respectively. Here, we performed a genome-wide screening for genes whose deletion induces FTY720-sensitive growth in S. pombe and identified 49 genes. These gene products are related to the biological processes involved in metabolic processes, transport, transcription, translation, chromatin organization, cytoskeleton organization and intracellular signal transduction. Notably, most of the FTY720-sensitive deletion cells exhibited NAC-remedial FTY720 sensitivities and dysregulated ROS homeostasis. Our results revealed a novel gene network involving ROS homeostasis and the possible mechanisms of the FTY720 toxicity.

SUBMITTER: Hagihara K

PROVIDER: S-EPMC5722642 | biostudies-literature | 2017 Nov

REPOSITORIES: biostudies-literature

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A genome-wide screen for FTY720-sensitive mutants reveals genes required for ROS homeostasis.

Hagihara Kanako K Kinoshita Kanako K Ishida Kouki K Hojo Shihomi S Kameoka Yoshinori Y Satoh Ryosuke R Takasaki Teruaki T Sugiura Reiko R

Microbial cell (Graz, Austria) 20171127 12

Fingolimod hydrochloride (FTY720), a sphingosine-1-phosphate (S1P) analogue, is an approved immune modulator for the treatment of multiple sclerosis (MS). Notably, in addition to its well-known mode of action as an S1P modulator, accumulating evidence suggests that FTY720 induces apoptosis in various cancer cells via reactive oxygen species (ROS) generation. Although the involvement of multiple signaling molecules, such as JNK (Jun N-terminal kinase), Akt (alpha serine/threonine-protein kinase) ...[more]

PMID: 29234668

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Project description:BackgroundFetal alcohol spectrum disorders (FASD) are a highly variable set of phenotypes caused by fetal alcohol exposure. Numerous factors influence FASD phenotypes, including genetics. The zebrafish is a powerful vertebrate model system with which to identify these genetic factors. Many zebrafish mutants are housed at the Zebrafish International Resource Center (ZIRC). These mutants are readily accessible and an excellent source to screen for ethanol (EtOH)-sensitive developmental structural mutants.MethodsWe screened mutants obtained from ZIRC for sensitivity to EtOH teratogenesis. Embryos were treated with 1% EtOH (41 mM tissue levels) from 6 hours postfertilization onward. Levels of apoptosis were evaluated at 24 hours postfertilization. At 4 days postfertilization, the craniofacial skeleton, peripheral axon projections, and sensory neurons of neuromasts were examined. Fish were genotyped to determine whether there were phenotype/genotype correlations.ResultsFive of 20 loci interacted with EtOH. Notable among these was that vangl2, involved in convergent extension movements of the embryonic axis, interacted strongly with EtOH. Untreated vangl2 mutants had normal craniofacial morphology, while severe midfacial defects including synophthalmia and narrowing of the palatal skeleton were found in all EtOH-treated mutants and a low percentage of heterozygotes. The cell cycle gene, plk1, also interacted strongly with EtOH. Untreated mutants have slightly elevated levels of apoptosis and loss of ventral craniofacial elements. Exposure to EtOH results in extensive apoptosis along with loss of neural tissue and the entire craniofacial skeleton. Phenotypes of hinfp, mars, and foxi1 mutants were also exacerbated by EtOH.ConclusionsOur results provide insight into the gene-EtOH interactions that may underlie EtOH teratogenesis. They support previous findings that EtOH disrupts elongation of the embryonic axis. Importantly, these results show that the zebrafish is an efficient model with which to test for gene-EtOH interactions. Understanding these interactions will be crucial to understanding of the FASD variation.

Project description:Drug resistance is a consequence of how most modern medicines work. Drugs exert pressure on cells that causes death or the evolution of resistance. Indeed, highly specific drugs are rendered ineffective by a single DNA mutation. In this study, we apply the drug methotrexate, which is widely used in cancer and rheumatoid arthritis, and perform evolution experiments on Baker's yeast to ask the different ways in which cells become drug resistant. Because of the conserved nature of biological pathways between yeast and man, our results can inform how the same mechanism may operate to render human cells resistant to treatment. Exposure of cells to small molecules and drug therapies imposes a strong selective pressure. As a result, cells rapidly acquire mutations in order to survive. These include resistant variants of the drug target as well as those that modulate drug transport and detoxification. To systematically explore how cells acquire drug resistance in an unbiased manner, rapid cost-effective approaches are required. Methotrexate, as one of the first rationally designed anticancer drugs, has served as a prototypic example of such acquired resistance. Known methotrexate resistance mechanisms include mutations that increase expression of the dihydrofolate reductase (DHFR) target as well as those that maintain function yet reduce the drug's binding affinity. Recent evidence suggests that target-independent, epistatic mutations can also result in resistance to methotrexate. Currently, however, the relative contribution of such unlinked resistance mutations is not well understood. To address this issue, we took advantage of Saccharomyces cerevisiae as a model eukaryotic system that combined with whole-genome sequencing and a rapid screening methodology, allowed the identification of causative mutations that modulate resistance to methotrexate. We found a recurrent missense mutation in SEC21 (orthologous to human COPG1), which we confirmed in 10 de novo methotrexate-resistant strains. This sec21 allele (S96L) behaves as a recessive, gain-of-function allele, conferring methotrexate resistance that is abrogated by the presence of a wild-type copy of SEC21 These observations indicate that the Sec21p/COPI transport complex has previously uncharacterized roles in modulating methotrexate stress.

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A genome-wide screen for FTY720-sensitive mutants reveals genes required for ROS homeostasis.

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A genome-wide screen for FTY720-sensitive mutants reveals genes required for ROS homeostasis.

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