Adaptive aneuploidy protects against thiol peroxidase deficiency by increasing respiration via key mitochondrial proteins
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ABSTRACT: We characterized the mechanisms that allow yeast cells to survive under conditions of thiol peroxidase deficiency. Two thiol peroxidase null yeast (delta8) strains independently acquired a second copy of chromosome XI and increased expression of genes encoded by it. Delta-8 strains were compared to the Wt-M11 strain, which is characterized by duplication of chr-XI.
Project description:Aerobic respiration is a fundamental energy-generating process; however, there is cost associated with living in an oxygen-rich environment, because partially reduced oxygen species can damage cellular components. Organisms evolved enzymes that alleviate this damage and protect the intracellular milieu, most notably thiol peroxidases, which are abundant and conserved enzymes that mediate hydrogen peroxide signaling and act as the first line of defense against oxidants in nearly all living organisms. Deletion of all eight thiol peroxidase genes in yeast (∆8 strain) is not lethal, but results in slow growth and a high mutation rate. Here we characterized mechanisms that allow yeast cells to survive under conditions of thiol peroxidase deficiency. Two independent ∆8 strains increased mitochondrial content, altered mitochondrial distribution, and became dependent on respiration for growth but they were not hypersensitive to H2O2. In addition, both strains independently acquired a second copy of chromosome XI and increased expression of genes encoded by it. Survival of ∆8 cells was dependent on mitochondrial cytochrome-c peroxidase (CCP1) and UTH1, present on chromosome XI. Coexpression of these genes in ∆8 cells led to the elimination of the extra copy of chromosome XI and improved cell growth, whereas deletion of either gene was lethal. Thus, thiol peroxidase deficiency requires dosage compensation of CCP1 and UTH1 via chromosome XI aneuploidy, wherein these proteins support hydroperoxide removal with the reducing equivalents generated by the electron transport chain. To our knowledge, this is the first evidence of adaptive aneuploidy counteracting oxidative stress.
Project description:Mycothiol (AcCys-GlcN-Ins, MSH) is the major thiol-redox buffer in Actinomycetes, including Mycobacterium and Corynebacterium species. ). Protein S-mycothiolation controls the activities of several redox enzymes that function in detoxification of ROS and methionine sulfoxides, including the thiol peroxidase Tpx, the mycothiol peroxidase Mpx and the methionine sulfoxide reductase MsrA. Here we investigated the level of protein S-mycothiolation in Mycobacterium smegmatis under oxidative stress as well as its NaOCl stress response.
Project description:Mycothiol (AcCys-GlcN-Ins, MSH) is the major thiol-redox buffer in Actinomycetes, including Mycobacterium and Corynebacterium species. Protein S-mycothiolation controls the activities of several redox enzymes that function in detoxification of ROS and methionine sulfoxides, including the thiol peroxidase Tpx, the mycothiol peroxidase Mpx and the methionine sulfoxide reductase MsrA. Here we investigated the level of protein S-mycothiolation in Corynebacterium diphtheriae DSM43989 under oxidative stress as well as its NaOCl stress response.
Project description:The main objective is to improve xylose fermentation by deletion of PHO13 gene in Xylose isomerase (XI) harboring yeast strains. Microarray analysis was performed to investigate effects of PHO13 deletion on the gene expression prolife of xylose-fermenting strains.
Project description:Aneuploidy causes a proliferative disadvantage in all normal cells analyzed to date, yet this condition is associated with a disease characterized by unabated proliferative potential, cancer. The mechanisms that allow cancer cells to tolerate the adverse effects of aneuploidy are not known. To probe this question, we identified aneuploid yeast strains with improved proliferative abilities. Their molecular characterization revealed strain-specific genetic alterations as well as mutations shared between different aneuploid strains. Among the latter, a loss-of-function mutation in the gene encoding the deubiquitinating enzyme Ubp6 improves growth rates in four different aneuploid yeast strains by attenuating the changes in intracellular protein composition caused by aneuploidy. Our results demonstrate the existence of aneuploidy-tolerating mutations that improve the fitness of multiple different aneuploidies and highlight the importance of ubiquitin-proteasomal degradation in suppressing the adverse effects of aneuploidy.
2010-02-25 | GSE20464 | GEO
Project description:Study of thiol peroxidase in Streptomycete rochei D74
Project description:Aneuploidy is a condition frequently found in tumor cells but how it affects cellular physiology is not known. We have characterized one aspect of aneuploidy, the gain of extra chromosomes. We created a collection of haploid yeast strains that each bear an extra copy of one or more of almost all of the yeast chromosomes. Their characterization revealed that aneuploid strains share a number of phenotypes, including defects in cell cycle progression, increased glucose uptake and increased sensitivity to conditions interfering with protein synthesis and protein folding. These phenotypes were observed only in strains carrying additional yeast genes indicating that they reflect the consequences of additional transcription and translation as well as the resulting imbalances in cellular protein composition. We conclude that aneuploidy causes not only a proliferative disadvantage but also a set of phenotypes that is independent of the identity of the individual extra chromosomes. Keywords: CGH, gene expression
Project description:Aneuploidy causes a proliferative disadvantage in all cells analyzed to date, yet this condition is associated with a disease characterized by unabated proliferative potential, cancer. The mechanisms that allow cancer cells to tolerate the adverse effects of aneuploidy are not known. To probe this question, we identified aneuploid yeast strains with high proliferative abilities and characterized their genetic alterations. We found both strain-specific genetic alterations and mutations shared between different aneuploid strains. One such mutation, a loss of function mutation in the gene encoding the deubiquitinating enzyme UBP6, improves growth rates in four different aneuploid yeast strains. Our data further suggest that deletion of UBP6 attenuates the effects of aneuploidy on cellular protein composition. Our results demonstrate the existence of aneuploidy-tolerating mutations that improve the fitness of multiple different aneuploidies and highlight the importance of ubiquitin-proteasomal degradation in suppressing the adverse effects of aneuploidy. This dataset contains both expression analysis and CGH of yeast strains bearing extra chromosomes. In all cases, the wt euploid strain grown under the same conditions was used as the reference sample. Reference nucleic acid was generally labeled with Cy3, though some were labeled with Cy5 as indicated in the associated annotations for each array. No replicate arrays are included. Expression Samples: GSM513249-GSM513277 CGH Samples: GSM513278-GSM513369
Project description:Histone deacetylase inhibitors (HDI) are among the growing class of epigenetic therapies used for the treatment of cancer. Although histone deacetylase inhibitors (HDIs) are effective in the treatment of T-cell lymphomas, solid tumors are largely resistant, and few mechanisms of resistance have been described. Overexpression of the multi-drug resistance gene ABCB1 that encodes P-glycoprotein (P-gp) is known to confer resistance to the HDI romidepsin, yet it is not associated with resistance in patients, suggesting other mechanisms of resistance arise in patients. To identify alternative romidepsin resistance mechanisms, we selected MCF-7 breast cancer cells with romidepsin in the presence of verapamil to reduce the chance of P-gp over-expression developing as a resistance mechanism. The resulting subline, MCF-7 DpVp300, does not express P-gp and was found to be selectively resistant to romidpesin but not other HDIs such as belinostat, panobinostat, or vorinostat. RNA sequencing analysis demonstrated upregulation of the putative methyltransferase, METTL7A, a paralog of which, METTL7B, was found to methylate thiol groups on hydrogen sulfide and captopril. We hypothesized that METTL7A could methylate and inactivate romidepsin as well as other HDIs with a thiol as the zinc binding group. Here we show that expression of METTL7A is necessary for thiol-based HDI resistance in the MCF-7 DpVp300 cell line, and that expression of METTL7A or METTL7B in sensitive cells confers resistance to thiol based HDIs. We thus propose that METTL7A and METTL7B confer resistance to thiol-based HDIs by methylating and inactivating the zinc-binding thiol.
Project description:Histone deacetylase inhibitors (HDI) are among the growing class of epigenetic therapies used for the treatment of cancer. Although histone deacetylase inhibitors (HDIs) are effective in the treatment of T-cell lymphomas, solid tumors are largely resistant, and few mechanisms of resistance have been described. Overexpression of the multi-drug resistance gene ABCB1 that encodes P-glycoprotein (P-gp) is known to confer resistance to the HDI romidepsin, yet it is not associated with resistance in patients, suggesting other mechanisms of resistance arise in patients. To identify alternative romidepsin resistance mechanisms, we selected MCF-7 breast cancer cells with romidepsin in the presence of verapamil to reduce the chance of P-gp over-expression developing as a resistance mechanism. The resulting subline, MCF-7 DpVp300, does not express P-gp and was found to be selectively resistant to romidpesin but not other HDIs such as belinostat, panobinostat, or vorinostat. RNA sequencing analysis demonstrated upregulation of the putative methyltransferase, METTL7A, a paralog of which, METTL7B, was found to methylate thiol groups on hydrogen sulfide and captopril. We hypothesized that METTL7A could methylate and inactivate romidepsin as well as other HDIs with a thiol as the zinc binding group. Here we show that expression of METTL7A is necessary for thiol-based HDI resistance in the MCF-7 DpVp300 cell line, and that expression of METTL7A or METTL7B in sensitive cells confers resistance to thiol based HDIs. We thus propose that METTL7A and METTL7B confer resistance to thiol-based HDIs by methylating and inactivating the zinc-binding thiol.