Oxidative Stress Induces Binding of FANCD2 to STAT5 and Facilitates STAT5-Dependent Survival Signals.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 33-33 ◽  
Author(s):  
Grover Bagby ◽  
Winifred Keeble ◽  
Tara Koretsky ◽  
Dylan Zodrow ◽  
Richard Jove ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Ground State ◽  
Mutant Cell ◽  
Extracellular Proteins ◽  
Wild Type ◽  
Direct Role ◽  
Normal Cells ◽  
Jak2 Inhibitor ◽  
Stat Signaling ◽  
Mutant Cells

Abstract Fanconi anemia (FA) cells are hypersensitive to oxidative stress and exhibit aberrant STAT activation responses to defined extracellular proteins but whether these abnormalities are linked is unclear. Because oxidative stress is known to induce STAT activation, we hypothesized that proper STAT signaling responses in normal cells exposed to H2O2 require intact FA proteins. In fact, we found that FA-C, FA-G, and FA-D2 cells (fibroblasts) showed a significant increase in apoptosis after H2O2-exposure compared to retrovirally-complemented cells. H2O2 induced higher phospho-STAT5 (P-STAT5) expression in complemented cells than in mutant cells. Conversely, mutant cells expressed higher levels of P-STAT3 in both the ground state and after H2O2-induction than complemented cells. Aberrant STAT activation in FA mutant cells was shown to be both nucleus- and JAK2 kinase-dependent. Only low levels of STAT3 and STAT5 were induced in both mutant and complemented cytoplasts and AG490 (a Jak2 inhibitor) significantly suppressed H2O2-induced STAT5 responses. Seeking a direct role of FANCD2 in regulating proper STAT activation responses to H2O2, we carried out immunoprecipitation experiments (with an antibody to the N-terminal fragment of FANCD2) using PD20, a FA-D2 mutant cell line, and FANCD2 complemented PD20. In FANCD2-complemented and normal cells, anti-FANCD2 antibody immunoprecipitated STAT5. However, in mutant cells the same antibody immunoprecipitated STAT3, not STAT5. Thus, mutant (truncated) FANCD2 preferentially binds to and may activate STAT3 in the ground state. In fact, wild type FANCD2 also binds aberrantly to STAT3 in HSC536 (FA-C lymphoblasts) indicating that FANCC may influence the function of wild type FANCD2 and that binding of wild type FANCD2 to STAT3 does not require FANCD2 ubiquitinylation (FANCD2 is not ubiquitinylated in FA-C). Suspecting that in H2O2-exposed cells STAT5 signaling pathways lead to survival while STAT3 pathways lead to apoptosis, we transduced constitutively active mutants (*) of STATs 3 and 5 in mutant D2 and complemented cells. STAT3* increased apoptotic responses to H2O2 in complemented FA-D2 cells and STAT5* decreased apoptotic responses in H2O2-induced FA-D2 cells. In addition, the STAT5 inducible anti-apoptotic gene Bcl-XL was induced in H2O2-exposed complemented FA-D2 cells but not in FA-D2 cells. We conclude that FANCD2 functions to promote survival by ordering proper STAT signaling responses to oxidative stress and that this function of FANCD2 depends in part upon FA-C. We propose that FA cells are hypersensitive to oxidative stress in part because of imbalanced STAT signal transduction responses.

scholarly journals Acquired Resistance to JAK Inhibitors in Calr-Mutated Myeloproliferative Neoplasms

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 2970-2970
Author(s):  
Ken-Hong Lim ◽  
Yu-Cheng Chang ◽  
Yi-Hao Chiang ◽  
Huan-Chau Lin ◽  
Ling Huang ◽  
...  
Keyword(s):  
Cell Lines ◽  
Acquired Resistance ◽  
Jak Inhibitor ◽  
Secondary Mutation ◽  
Wild Type ◽  
Jak Inhibitors ◽  
Jak2 Inhibitor ◽  
Stat Signaling ◽  
Calr Mutations ◽  
Mutant Cells

Background: Calreticulin (CALR) mutations are one of the major driver mutations in BCL-ABL1-negative myeloproliferative neoplasm (MPN) and are frequently detected in JAK2/MPL-unmutated essential thrombocythemia and primary myelofibrosis. Mutant CALR activates JAK-STAT signaling through an MPL-dependent mechanism to mediate pathogenic thrombopoiesis in MPNs. Although JAK inhibitors such as ruxolitinib can provide important clinical benefits to MPN patients including those harboring CALR mutations, JAK inhibition does not preferentially target the MPN clone and acquired resistance develops over time. We aimed to characterize the mechanisms of acquired resistance to JAK inhibitors in CALR-mutated hematopoietic cells and to screen for novel therapeutic approaches specifically target CALR-mutant cells in this study. Methods: UT-7/TPO-derived cell lines expressing wild-type and type 1 and type 2 mutant CALR (CALRdel52 and CALRins5) were kindly provided by Drs. Komatsu and Araki. JAK2-inhibitor-resistant cells were generated by co-cultured with ruxolitinib and fedratinib (TG101348, a JAK2-selective inhibitor). JAK-STAT signaling was evaluated by Western blot on CALR-wild-type and mutated cells exposed to JAK2 inhibitor compared to untreated cells. For the detection of acquired secondary mutations in CALR-mutated cells exposed to JAK2 inhibitor, whole exome sequencing (WES) was performed using the BGISEQ-500 Sequencing platform (BGI, Shenzhen, China) with the 2 x 100 bp paired-end protocol. Genome Analysis Toolkit was used for variation detection. Reads were aligned to human reference genome hg19 using BWA version 0.7.15. Targeted resequencing was performed on leukocytes from patients with MPN who had been treated with ruxolitinib. Screening with chemical libraries/novel compounds will be conducted on UT7/TPO-CALR cell lines. Results: Compared to the parental cells, ruxolitinib-resistant UT7/TPO-CALR mutant cell lines have developed significant cross resistance to other JAK inhibitor as shown in the cell viability study. Signalling downstream of JAK2 in all 3 inhibitor-naïve UT-7/TPO/CALR parental cell lines was inhibited by acute treatment of ruxolitinib as shown on Western blot. Whereas, constitutive JAK2 activation was observed in all 3 inhibitor-resistant UT-7/TPO/CALR cell lines. No change in the expression of Epo and MPL receptors in these cell lines was found. Interestingly, constitutive JAK3 activation was also seen in inhibitor-resistant UT-7/TPO/CALR cells in comparison with parental cells. These findings indicated the presence of transphosphorylation by JAK3 in inhibitor-resistant UT-7/TPO/CALR cell lines. In addition, the results of WES identified several acquired secondary mutations in 3 inhibitor-resistant UT-7/TPO/CALR cell lines including SH2B1, ABCC1, HOXB3 and KRTAP4-5. No acquired secondary mutation was identified in CALR and other genes involved in JAK-STAT signaling. Acquired secondary mutation will be screened in primary MPN patients' samples treated with JAK inhibitor. Type II JAK inhibitor such as BBT-594 has been shown to inhibit JAK activation and signaling in JAK-persistent/resistant cells. Conclusions: Our results confirmed that the in vitro efficacy of JAK2 inhibition on CALR-mutant cells. Our data also suggested that JAK2 transphosphorylation and acquired secondary mutations could be underlying mechanisms for acquired resistance to JAK inhibitors in CALR-mutated cells. Novel therapeutics approaches should be developed to overcome acquired resistance in CALR-mutated cells. Disclosures No relevant conflicts of interest to declare.

Mutants lacking myosin II cannot resist forces generated during multicellular morphogenesis

1995 ◽  
Vol 108 (3) ◽  
pp. 1105-1115 ◽  
Author(s):  
E. Shelden ◽  
D.A. Knecht
Keyword(s):  
Cell Morphology ◽  
Mutant Cell ◽  
Myosin Ii ◽  
Cell Phenotype ◽  
Computer Assisted ◽  
Wild Type ◽  
Isolated Cells ◽  
Multicellular Development ◽  
Periodic Movement ◽  
Mutant Cells

We have used fluorescent labeling, confocal microscopy and computer-assisted motion analysis to observe and quantify individual wild-type and myosin II mutant cell behavior during early multicellular development in Dictyostelium discoideum. When cultured with an excess of unlabeled wild-type cells, labeled control cells are randomly distributed within aggregation streams, while myosin II mutant cells are found primarily at the lateral edges of streams. Wild-type cells move at average rates of 8.5 +/- 4.9 microns/min within aggregation streams and can exhibit regular periodic movement at 3.5 minute intervals; half as long as the 7 minute period reported previously for isolated cells. Myosin II mutants under the same conditions move at 5.0 +/- 4.8 microns/min, twice as fast as reported previously for isolated myosin II mutant cells, and fail to display regular periodic movement. When removed from aggregation streams myosin II mutant cells move at only 2.5 +/- 2.0 microns/min, while wild-type cells under these conditions move at 5.9 +/- 4.5 microns/min. Analysis of cell morphology further reveals that myosin II mutant cells are grossly and dynamically deformed within wild-type aggregation streams but not when removed from streams and examined in isolation. These data reveal that the loss of myosin II has dramatic consequences for cells undergoing multicellular development. The segregation of mutant cells to aggregation stream edges demonstrates that myosin II mutants are unable to penetrate a multicellular mass of wild-type cells, while the observed distortion of myosin II mutant cells suggests that the cortex of such cells is too flacid to resist forces generated during movement. The increased rate of mutant cell movement and distortion of mutant cell morphology seen within wild-type aggregation streams further argues both that movement of wild-type cells within a multicellular mass can generate traction forces on neighboring cells and that mutant cell morphology and behavior can be altered by these forces. In addition, the distortion of myosin II mutant cells within wild-type aggregation streams indicates that myosin is not required for the formation of cell-cell contacts. Finally, the consequences of the loss of myosin II for cells during multicellular development are much more severe than has been previously revealed for isolated cells. The techniques used here to analyze the behavior of individual cells within multicellular aggregates provide a more sensitive assay of mutant cell phenotype than has been previously available and will be generally applicable to the study of motility and cytoskeletal mutants in Dictyostelium.

scholarly journals Transposition of Insertion Sequences was Triggered by Oxidative Stress in Radiation-Resistant Bacterium Deinococcus geothermalis

2019 ◽  
Vol 7 (10) ◽  
pp. 446 ◽  
Author(s):  
Chanjae Lee ◽  
Nakjun Choi ◽  
Min K. Bae ◽  
Kyungsil Choo ◽  
Sung-Jae Lee
Keyword(s):  
Oxidative Stress ◽  
Family Member ◽  
Mutant Strain ◽  
Mutant Cell ◽  
Carotenoid Biosynthesis ◽  
Wild Type ◽  
Is Element ◽  
Deinococcus Geothermalis ◽  
Key Enzyme ◽  
Radiation Resistant

During an oxidative stress-response assay on a putative Dps-like gene-disrupted Δdgeo_0257 mutant strain of radiation-resistant bacterium Deinococcus geothermalis, a non-pigmented colony was observed among the normal reddish color colonies. This non-pigmented mutant cell subsequently displayed higher sensitivity to H2O2. While carotenoid has a role in protecting as scavenger of reactive oxygen species the reddish wild-type strain from radiation and oxidative stresses, it is hypothesized that the carotenoid biosynthesis pathway has been disrupted in the mutant D. geothermalis cell. Here, we show that, in the non-pigmented mutant cell of interest, phytoene desaturase (Dgeo_0524, crtI), a key enzyme in carotenoid biosynthesis, was interrupted by transposition of an ISDge7 family member insertion sequence (IS) element. RNA-Seq analysis between wild-type and Δdgeo_0257 mutant strains revealed that the expression level of ISDge5 family transposases, but not ISDge7 family members, were substantially up-regulated in the Δdgeo_0257 mutant strain. We revealed that the non-pigmented strain resulted from the genomic integration of ISDge7 family member IS elements, which were also highly up-regulated, particularly following oxidative stress. The transposition path for both transposases is a replicative mode. When exposed to oxidative stress in the absence of the putative DNA binding protein Dgeo_0257, a reddish D. geothermalis strain became non-pigmented. This transformation was facilitated by transposition of an ISDge7 family IS element into a gene encoding a key enzyme of carotenoid biosynthesis. Further, we present evidence of additional active transposition by the ISDge5 family IS elements, a gene that was up-regulated during the stationary phase regardless of the presence of oxidative stress.

Phosphorylation of the myosin regulatory light chain plays a role in motility and polarity duringDictyosteliumchemotaxis

2002 ◽  
Vol 115 (8) ◽  
pp. 1733-1747 ◽  
Author(s):  
Hui Zhang ◽  
Deborah Wessels ◽  
Petra Fey ◽  
Karla Daniels ◽  
Rex L. Chisholm ◽  
...  
Keyword(s):  
Light Chain ◽  
Mutant Cell ◽  
Cell Aggregation ◽  
Regulatory Light Chain ◽  
Computer Assisted ◽  
Spatial Gradient ◽  
Myosin Regulatory Light Chain ◽  
Cellular Polarity ◽  
Wild Type ◽  
Mutant Cells

The myosin regulatory light chain (RLC) of Dictyostelium discoideum is phosphorylated at a single serine site in response to chemoattractant. To investigate the role of the phosphorylation of RLC in both motility and chemotaxis, mutants were generated in which the single phosphorylatable serine was replaced with a nonphosphorylatable alanine. Several independent clones expressing the mutant RLC in the RLC null mutant, mlcR-, were obtained. These S13A mutants were subjected to high resolution computer-assisted motion analysis to assess the basic motile behavior of cells in the absence of a chemotatic signal, and the chemotactic responsiveness of cells to the spatial, temporal and concentration components of natural cAMP waves. In the absence of a cAMP signal, mutant cells formed lateral pseudopods less frequently and crawled faster than wild-type cells. In a spatial gradient of cAMP, mutant cells chemotaxed more efficiently than wild-type cells. In the front of simulated temporal and natural waves of cAMP,mutant cells responded normally by suppressing lateral pseudopod formation. However, unlike wild-type cells, mutant cells did not lose cellular polarity at the peak and in the back of either wave. Since depolarization at the peak and in the descending phase of the natural wave is necessary for efficient chemotaxis, this deficiency resulted in a decrease in the capacity of S13A mutant cells to track natural cAMP waves relayed by wild-type cells, and in the fragmentation of streams late in mutant cell aggregation. These results reveal a regulatory pathway induced by the peak and back of the chemotactic wave that alters RLC phosphorylation and leads to cellular depolarization. We suggest that depolarization requires myosin II rearrangement in the cortex facilitated by RLC phosphorylation, which increases myosin motor function.

The effect of TAE226 on the non-small cell lung cancer including Japanese origin lung cancer

2009 ◽  
Vol 27 (15_suppl) ◽  
pp. e22103-e22103
Author(s):  
H. Otani ◽  
M. Jida ◽  
M. Takaoka ◽  
T. Kubo ◽  
T. Hayashi ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cell Lines ◽  
Egfr Mutation ◽  
Mutant Cell ◽  
Small Cell ◽  
Nsclc Cell ◽  
Wild Type ◽  
Small Cell Lung ◽  
Egfr Mutant ◽  
Mutant Cells

e22103 Background: Mutations in the epidermal growth factor receptor (EGFR) gene is the predictive factor for sensitivity of EGFR tyrosine kinase inhibitors (TKIs) in non-small cell lung cancer. Focal adhesion kinase (FAK) that is the downstream molecule of EGFR has been reported to be highly expressed in NSCLC suggesting novel therapeutic target of NSCLC. TAE226, dual inhibitor for FAK and insulin like growth factor-I receptor (IGF-IR), have been developed as anticancer reagent. In this study, we examined the effect of TAE226 on NSCLC from the view point of EGFR mutation status. Methods: We used NSCLC cell lines consisting of 4 EGFR mutant cell lines (PC9, H3255, HCC827, H1975) and 3 EGFR wild type cell lines (H1819, H1299, A549). We also used PC9 derived resistant cell line (RPC9). Antiproliferative effect of TAE226 on NSCLC cell lines was examined with MTS assay. The status of EGFR related molecules including its downstream signal pathway was investigated by western blotting analysis. The effect of TAE226 on xenograft mouse models was also examined. Results: TAE226 was effective on NSCLC cell lines with EGFR mutation including T790M mutation, compared to those with EGFR wild type. The value of IC50 (μmol/L) for PC-9, H3255, HCC827, H1975, RPC-9 and H1819, H1299, A549 was 0.16, 0.12, 0.086, 0.17, 0.31 and 4.7, 2.8, 1.4, respectively. Western blotting assay showed that TAE226 preferentially inhibited phosphor-EGFR and its downstream signaling mediators. We could confirm the anticancer effect of TAE226 on EGFR mutant cells was confirmed in xenograft mouse models. Conclusions: We indicated that TAE226 showed antitumor effect on EGFR mutant cell lines even T790M mutant cells. Further study is necessary to understand the mechanism of TAE226 effect on EGFR mutant cell lines. Our results suggest that TAE226 will be expected as the novel strategy for NSCLC. No significant financial relationships to disclose.

scholarly journals Localization of T25 glycoprotein in wild-type and Thy 1- mutant cells by immunofluorescence and immunoelectron microscopy.

1978 ◽  
Vol 147 (5) ◽  
pp. 1348-1354 ◽  
Author(s):  
L Y Bourguignon ◽  
R Hyman ◽  
I Trowbridge ◽  
S J Singer
Keyword(s):  
Cell Surface ◽  
Cell Line ◽  
Immunoelectron Microscopy ◽  
Mutant Cell ◽  
Wild Type Cell ◽  
Wild Type ◽  
Mutant Cell Line ◽  
Mutant Derivative ◽  
Mutant Cells

The wild-type BW5147 (Thy 1+) cell line and its Thy 1- mutant derivative BW5147 (Thy 1-a) were examined by immunofluorescence and immunoelectron microscopy for the presence of T25, the glycoprotein which bears the Thy 1 alloantigen. The wild-type cell had T25 predominantly localized on the cell surface. In the mutant cell line, T25 accumulated intracellularly and was present in a clustered distribution throughout the cytoplasm. T25 was not present on the surface of the mutant cell line in significant amount.

scholarly journals Extracellular Reduction of Hexavalent Chromium by Cytochromes MtrC and OmcA of Shewanella oneidensis MR-1

2011 ◽  
Vol 77 (12) ◽  
pp. 4035-4041 ◽  
Author(s):  
Sara M. Belchik ◽  
David W. Kennedy ◽  
Alice C. Dohnalkova ◽  
Yuanmin Wang ◽  
Papatya C. Sevinc ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Extracellular Matrix ◽  
Outer Membrane ◽  
Initial Rate ◽  
Mutant Cell ◽  
Shewanella Oneidensis ◽  
Wild Type ◽  
Content Type ◽  
Transmission Electron ◽  
Mutant Cells

ABSTRACTTo characterize the roles of cytochromes MtrC and OmcA ofShewanella oneidensisMR-1 in Cr(VI) reduction, the effects of deleting themtrCand/oromcAgene on Cr(VI) reduction and the cellular locations of reduced Cr(III) precipitates were investigated. Compared to the rate of reduction of Cr(VI) by the wild type (wt), the deletion ofmtrCdecreased the initial rate of Cr(VI) reduction by 43.5%, while the deletion ofomcAor bothmtrCandomcAlowered the rate by 53.4% and 68.9%, respectively. In wt cells, Cr(III) precipitates were detected by transmission electron microscopy in the extracellular matrix between the cells, in association with the outer membrane, and inside the cytoplasm. No extracellular matrix-associated Cr(III) precipitates, however, were found in the cytochrome mutant cell suspension. In mutant cells without either MtrC or OmcA, most Cr(III) precipitates were found in association with the outer membrane, while in mutant cells lacking both MtrC and OmcA, most Cr(III) precipitates were found inside the cytoplasm. Cr(III) precipitates were also detected by scanning election microscopy on the surfaces of the wt and mutants without MtrC or OmcA but not on the mutant cells lacking both MtrC and OmcA, demonstrating that the deletion ofmtrCandomcAdiminishes the extracellular formation of Cr(III) precipitates. Furthermore, purified MtrC and OmcA reduced Cr(VI) with apparentkcatvalues of 1.2 ± 0.2 (mean ± standard deviation) and 10.2 ± 1 s−1andKmvalues of 34.1 ± 4.5 and 41.3 ± 7.9 μM, respectively. Together, these results consistently demonstrate that MtrC and OmcA are the terminal reductases used byS. oneidensisMR-1 for extracellular Cr(VI) reduction where OmcA is a predominant Cr(VI) reductase.

scholarly journals Simulations reveal that different responses to cell crowding determine the expansion of p53 and Notch mutant clones in squamous epithelia

2021 ◽  
Vol 18 (183) ◽  
Author(s):  
Vasiliki Kostiou ◽  
Michael W. J. Hall ◽  
Philip H. Jones ◽  
Benjamin A. Hall
Keyword(s):  
Local Density ◽  
Mutant Cell ◽  
Wild Type ◽  
Logistic Curve ◽  
Type Population ◽  
Local Cell ◽  
Local Crowding ◽  
Mutant Cells ◽  
Human And Mouse ◽  
Putative Mechanism

During ageing, normal epithelial tissues progressively accumulate clones carrying mutations that increase mutant cell fitness above that of wild-type cells. Such mutants spread widely through the tissues, yet despite this cellular homeostasis and functional integrity of the epithelia are maintained. Two of the genes most commonly mutated in human skin and oesophagus are p53 and Notch1 , both of which are also recurrently mutated in cancers of these tissues. From observations taken in human and mouse epithelia, we find that clones carrying p53 and Notch pathway mutations have different clone dynamics which can be explained by their different responses to local cell crowding. p53 mutant clone growth in mouse epidermis approximates a logistic curve, but feedbacks responding to local crowding are required to maintain tissue homeostasis. We go on to show that the observed ability of Notch pathway mutant cells to displace the wild-type population in the mouse oesophageal epithelium reflects a local density feedback that affects both mutant and wild-type cells equally. We then show how these distinct feedbacks are consistent with the distribution of mutations observed in human datasets and are suggestive of a putative mechanism to constrain these cancer-associated mutants.

scholarly journals Transcription Factor Eb Is Required for Macropinocytosis-Mediated Growth Recovery of Nutrient-Deprived Kras-Mutant Cells

Nutrients ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1638
Author(s):  
Seokmin Jeong ◽  
Jun-Kyu Byun ◽  
Sung Cho ◽  
Jungwook Chin ◽  
In-Kyu Lee ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Growth ◽  
Cancer Cells ◽  
Human Cancer ◽  
Mutant Cell ◽  
Extracellular Proteins ◽  
Extracellular Protein ◽  
Lysosomal Degradation ◽  
Transcription Factor Eb ◽  
Mutant Cells

Macropinocytosis is a regulated form of endocytosis that mediates the nonselective uptake of nutrients to support growth under nutrient-deprived conditions. KRAS-mutant cancer cells upregulate macropinocytosis to import extracellular proteins, which subsequently undergo proteolytic degradation in the lysosome. Although transcription factor EB (TFEB) is a master regulator of lysosomal biogenesis and function, its role in the degradation of extracellular protein from macropinocytosis in KRAS-mutant cells has not previously been elucidated. In this study, we investigated the role of TFEB in the recovery of macropinocytosis-mediated mTORC1 activity and cell growth under nutrient depletion. Mouse embryonic fibroblasts (MEFs) expressing KrasG12D and KRAS-mutant human cancer cells took up markedly higher levels of tetramethylrhodamine (TMR)-dextran than the corresponding wild-type cells. siRNA-mediated inhibition of TFEB did not influence extracellular TMR-dextran uptake, but significantly attenuated lysosomal degradation of extracellular protein. Bovine serum albumin (BSA) treatment restored p-S6K levels and cell proliferation suppressed by leucine deprivation, and these effects were blocked by siTFEB. Collectively, our results show that TFEB plays a role in macropinocytosis-mediated KRAS-mutant cell growth under nutrient deprivation by promoting lysosomal degradation of extracellular proteins.

scholarly journals Importance of catalase in the adaptive response to hydrogen peroxide: analysis of acatalasaemic Saccharomyces cerevisiae

1996 ◽  
Vol 320 (1) ◽  
pp. 61-67 ◽  
Author(s):  
Shingo IZAWA ◽  
Yoshiharu INOUE ◽  
Akira KIMURA
Keyword(s):  
Oxidative Stress ◽  
Saccharomyces Cerevisiae ◽  
Adaptive Response ◽  
Yeast Cells ◽  
Exponential Growth Phase ◽  
Wild Type ◽  
Single Mutant ◽  
Mutant Cells ◽  
Similar Growth

Controversy about the importance of catalase in the detoxification of H2O2 in human erythrocytes continues. It has been suggested that catalase has no role in the clearance of H2O2 in erythrocytes. In the present study we investigated the role of catalase in the defence mechanism against oxidative stress using Saccharomyces cerevisiae. S. cerevisiae has two catalases, catalase A and catalase T. We constructed a double mutant (acatalasaemic mutant) unable to produce either catalase A or catalase T, and compared it with wild-type and single-mutant cells. The acatalasaemic mutant cells showed a similar growth rate to wild-type cells under non-oxidative stress conditions, and showed a similar susceptibility to H2O2 stress in the exponential growth phase. The acatalasaemic mutant cells at stationary phase were, however, much more sensitive to H2O2 stress than wild-type and single-mutant cells. Moreover, the ability of acatalasaemic and single-mutant cells to show adaptation to 2 mM H2O2 was distinctly inferior to that of wild-type cells. These results suggest that catalase is not essential for yeast cells under normal conditions, but plays an important role in the acquisition of tolerance to oxidative stress in the adaptive response of these cells.

Sign in / Sign up

Export Citation Format

Share Document