Unsaturation of very-long-chain ceramides regulates hypoxia response by modulating ethylene signaling in Arabidopsis
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana
SUBMITTER: Lujun Yu
PROVIDER: E-GEOD-59719 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:Lipid remodeling is crucial for hypoxic tolerance in animals, whilst little is known about the hypoxia-induced lipid dynamics in plant cells. Here we performed a mass spectrometry-based analysis to survey the lipid profiles of Arabidopsis rosettes under various hypoxic conditions. We observed that hypoxia caused a significant increase in total amounts of phosphatidylserine, phosphatidic acid and oxylipins, but a decrease in phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Particularly, significant gains in the polyunsaturated species of PC, PE and phosphatidylinositol, and losses in their saturated and mono-unsaturated species were evident during hypoxia. Moreover, hypoxia led to a remarkable elevation of ceramides and hydroxyceramides. Depletion of ceramide synthases LOH1, LOH2, and LOH3 enhanced plant sensitivity to dark submergence (DS), but displayed more resistance to submergence under light than wild type. Consistently, levels of unsaturated ceramide species (22:1, 24:1, and 26:1) predominantly declined in the loh1, loh2, and loh3 mutants under DS. Evidence that C24:1-ceramide interacted with recombinant CTR1 protein in vitro, enhanced ER-to-nucleus translocation of EIN2-GFP and stabilization of EIN3-GFP in vivo, suggests a role of ceramides in modulating ethylene signaling. The DS-sensitive phenotypes of loh mutants were rescued by a ctr1-1 mutation. Thus, our findings demonstrate that unsaturation of very-long-chain ceramides is a protective strategy for hypoxic tolerance in Arabidopsis.
2016-07-24 | GSE59719 | GEO
Project description:General translational repression is predicted as a key process to reduce energy consumption under hypoxia. We have previously showed that mRNA loading onto polysome is reduced in Arabidopsis under submergence. Here, we showed that plant stress activated GCN2 (general control nonderepressible 2) can phosphorylate eIF2a (Eukaryotic Initiation Factor 2a) in Arabidopsis under submergence, and this process is reversible after desubmergence. Compared to the wild-type, the reduction in polysome loading during submergence was less severe in the gcn2 mutant. Transgenic lines overexpressing GCN2 had more ATP and conferred better tolerance under submergence, suggesting that GCN2 might modulate the dynamics of translation to adjust the energy homeostasis under hypoxia. Interestingly, GCN2-eIF2a signaling was activated by ethylene under submergence. However, GCN2 activity was not affected in ein2-5 and eil1ein3 under submergence, suggesting that GCN2 activity was regulated by noncanonical ethylene signaling. In addition, the polysome loading was retained in both ein2-5 and etr1-1 under submergence, implying that ethylene modulated the dynamic translation under submergence via EIN2 and GCN2. Notably, our NGS analysis also demonstrated that EIN2 and GCN2 regulated the translation of 23 core hypoxia genes as well as 53% translational repressed genes under submergence. On the other hand, EIN2 and GCN2 also affected the expression of genes involved in hypoxic response, ethylene response, biotic stress and negative regulation of cytokinin signaling. Taken together, these demonstrated that entrapped ethylene triggers GCN2 and EIN2 to ensure the translation of stress required proteins under submergence and also provide a step stone for future investigation how eukaryotic cells modulate the translation to response for the changeable environments.
2022-06-08 | GSE149414 | GEO
Project description:Down syndrome (DS) patients frequently develop organ-specific autoimmune disorders, particularly endocrinopathies and coeliac disease, as well as an increased susceptibility to mucosal candidiasis. These clinical features resemble APECED (autoimmune-polyendocrinopathy-candidiasis-ectodermal-dystrophy), a monogenic condition due to mutations in the AIRE gene, located on 21q22.3 and already described as down-regulated in 21 trisomy. Here we investigated AIRE expression and global gene expression profiles in surgically removed thymuses from 14 DS infants and children with congenital heart defects and from 42 age-matched individuals with cardiac defect as an isolated malformation. Immunohistochemistry revealed significantly reduced AIRE expression in DS thymuses (70.48M-BM-149.59 positive cells/mm2 in DS X 154.70M-BM-161.16 in controls, p<0.0001). qPCR confirmed the lower expression of AIRE in DS thymuses. Global thymic RNA profiles from DS patients and controls revealed 407 genes significantly hypoexpressed in DS. Network transcriptional analysis showed that hypoexpressed genes are related to biological processes such as antigen processing and presentation of endogenous antigen (ERAP2, CD1D), negative (PRDX2) and positive (CD3D, CD74) thymic T-cell selection and homeostasis of number of cells (PRDX2). Altogether these findings may explain the high prevalence of autoimmune phenomena in DS patients. Moreover, our data are in accordance with previous findings of thymic abnormal development in DS patients, characterized by lymphocyte depletion, diminution of the cortex, and loss of corticomedullary demarcation. Global gene profiles indicate that in DS patients, the trisomic imbalance probably leads to thymic hypofunction. In conclusion, lower AIRE expression and the impairment of other crucial pathways for central tolerance could well explain the high prevalence of organ-specific autoimmune disorders in DS. Among the 14 DS infants and 42 age-matched individuals with cardiac defect, only 4 from each group provided enough biological material (thymus fragments) for isolation of high-quality RNA to perform array analysis. Eight thymic samples were analyzed: C1, C2, C3 and C4 are controls, and D1, D2, D3 and D4 are from patients with Down syndrome.
2011-11-28 | E-GEOD-23910 | biostudies-arrayexpress
Project description:The environment inside even a small tumor is characterized by total (anoxia) or partial oxygen deprivation, hypoxia. It has been shown that radiotherapy and some conventional chemotherapies may be less effective in hypoxia, and therefore it is important to investigate how different drugs act in different microenvironments. In the associated study we performed a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on four different cell lines in conditions of normoxia, hypoxia and anoxia. A panel of 19 commercially available drugs: 5-fluorouracil, acriflavine, bortezomib, cisplatin, digitoxin, digoxin, docetaxel, doxorubicin, etoposide, gemcitabine, irinotecan, melphalan, mitomycin c, rapamycin, sorafenib, thalidomide, tirapazamine, topotecan and vincristine were tested for cytotoxic activity on the cancer cell lines A2780 (ovarian), ACHN (renal), MCF-7 (breast), H69 (SCLC) and U-937 (lymphoma). Parallel aliquots of the cells were grown at different oxygen pressures and after 72 hours of drug exposure viability was measured with the fluorometric microculture cytotoxicity assay (FMCA). Sorafenib, irinotecan and docetaxel were in general more effective in an oxygenated environment, while cisplatin, mitomycin c and tirapazamine were more effective in a low oxygen environment. Surprisingly, hypoxia in H69 and MCF-7 cells mostly rendered higher drug sensitivity. In contrast ACHN appeared more sensitive to hypoxia, giving slower proliferating cells, and consequently, was more resistant to most drugs. Gene expression analysis was performed on MCF-7 cells after 90 hours in either anoxic or hypoxic conditions, and compared to cells grown in a regular cell incubator. The gene expression analysis was performed to validate that the cells were hypoxic/anoxic and showed the characteristic hypoxia response. Microarray based mRNA profiling was used to charactarize cells grown in hypoxia and anoxia. In the associated study we performed a large screening of the effects of 19 clinically used or experimental chemotherapeutic drugs on four different cell lines in conditions of normoxia, hypoxia and anoxia. We fin that hypoxia/anoxia render cancer cells both more resistant and more sensistive, depending of the type of drug used. The gene expression analysis was performed to validate that the cells really were hypoxic/anoxic and showed the characteristic hypoxia response. The cell line used for the gene expression analysis was MCF-7.
2014-05-04 | E-GEOD-47009 | biostudies-arrayexpress
Project description:Submergence induces hypoxia in plants; exposure to oxygen following submergence, termed reoxygenation, produces a burst of reactive oxygen species. The mechanisms of hypoxia sensing and signaling in plants have been well studied, but how plants respond to reoxygenation remains unclear. Here, we show that reoxygenation in Arabidopsis thaliana involves rapid accumulation of jasmonates (JAs) and increased transcript levels of JA biosynthesis genes. Application of exogenous methyl jasmonate improved tolerance to reoxygenation in wild-type Arabidopsis; also, mutants deficient in JA biosynthesis and signaling were very sensitive to reoxygenation. Moreover, overexpression of the transcription factor gene MYC2 enhanced tolerance to post-hypoxic stress and myc2 knockout mutants showed increased sensitivity to reoxygenation, indicating that MYC2 functions as a key regulator in the JA-mediated reoxygenation response. MYC2 transcriptionally activates members of the VITAMIN C DEFECTIVE (VTC) and GLUTATHIONE SYNTHETASE (GSH) gene families, which encode rate-limiting enzymes in the ascorbate and glutathione synthesis pathways. Overexpression of VTC1 and GSH1 in the myc2-2 mutant suppressed the post-hypoxic hypersensitive phenotype. The JA-inducible accumulation of antioxidants may alleviate oxidative damage caused by reoxygenation, improving plant survival after submergence. Taken together, our findings demonstrate that JA signaling interacts with the antioxidant pathway to regulate reoxygenation responses in Arabidopsis.
2017-08-25 | GSE93393 | GEO
Project description:Hypoxia is an important condition in the tumor cell microenvironment and approximately 1-1.5% of the genome is transcriptionally responsive to hypoxia with hypoxia-inducible factor-1 (HIF-1) as a major mediator of transcriptional activation. Tumor hypoxia is associated with a more aggressive phenotype of many cancers in adults, but data on pediatric tumors are scarce. By immunohistochemical analysis, HIF-1α expression was readily detectable in 18/28 primary Ewing´s sarcoma family tumors (ESFT), a group of highly malignant bone-associated tumors in children and young adults, which encouraged us to study the effect of hypoxia on ESFT cell lines in vitro. Many tumors are profoundly hypoxic and multiple studies have demonstrated that hypoxic tumors have a poorer prognosis than non-hypoxic tumors. The cellular adaptations of cancer cells to hypoxia have been shown to profoundly influence transcriptional regulation. Intriguingly, we found that EWS-FLI1 protein expression, which characterizes ESFT, is up-regulated by hypoxia in a HIF-1α-dependent manner. Hypoxia modulated the EWS-FLI1 transcriptional signature relative to normoxic conditions. Both synergistic as well as antagonistic transcriptional effects of EWS-FLI1 and of hypoxia were observed. Consistent with alterations in the expression of metastasis related genes, hypoxia stimulated the invasiveness and soft-agar colony formation of ESFT cells in vitro. Our data represents the first transcriptome analysis of hypoxic ESFT cells and identifies hypoxia as an important microenvironmental factor modulating EWS-FLI1 expression and target gene activity with far-reaching consequences for the malignant properties of ESFT. Experiment Overall Design: We analysed the consequences of hypoxia on gene expression in two ESFT cell lines (SK-N-MC, TC252) grown as multicellular spheroids and as adherent monolayers.
2010-02-05 | E-GEOD-19197 | biostudies-arrayexpress
Project description:Hypoxia triggers aggressive cancer growth and contributes to chemotherapy resistance. Novel therapeutic strategies aim at targeting hypoxia activated signaling pathways. Tumor hypoxia not only affects neoplastic tumor cells but also the surrounding stroma cells. Therefore, a novel ex vivo model was established, which allows the study of hypoxia effects in fragments of non-small cell lung cancer (NSCLC) with preserved tumor microenvironment and 3D-structure. Microarray analysis identified 107 significantly regulated genes with at least two-fold expression change in hypoxic compared to normoxic fragments. However, only four genes were significantly regulated in both subtypes, adenocarcinoma and squamous cell carcinoma. The hypoxic regulation of these four genes was verified in an independent set using quantitative PCR. Non-small cell lung cancer (NSCLC) fragments were cultured ex vivo under hypoxia or normoxia for three days. cDNA microarray analysis was performed in hypoxic and normoxic lung cancer fragments from ten patients.
2011-07-27 | E-GEOD-30979 | biostudies-arrayexpress
Project description:The bioactive sphingolipid ceramide, generated by ceramide synthase, is an adaptive stress effector induced in response to various stress stimuli such as aging. In fact, ceramide synthase (CerS) was first discovered in yeast as a longevity assurance gene (LAG1), as the reduced ceramide generation consequent to LAG1 deletion increased longevity. There are six homologues of mammalian LAG1/ceramide synthases (CerS1-6) that generate ceramides with different fatty acid chain lengths with distinct functions and hydrophobicity. Ceramide can be metabolized by sphingosine kinase 1 or 2 for the generation of pro-survival sphingosine 1-phosphate (S1P), which enhances immune cell egress to the blood stream, activating immune function. Ceramide is known to induce mitophagy and cell death. Here we investigated the role of this sphingolipid pathway in immune function, specifically T cell functions, via high throughput expression profiling.
2021-01-01 | GSE148498 | GEO
Project description:To determine hypoxia mediated changes in whole blood, normal swiss webster mice were gradually exposed to a chronic hypobaric hypoxic environment up to 8500m, for 2 weeks in vivo. Control, age-matched mice were maintained under normoxic conditions in Kathmandu (c. 1300 mts above sea level). Purpose: To examine and characterize the expression profile of genes expressed at hypobaric hypoxia on Mt. Everest of whole blood in comparison to the control. Methods: At the beginning of the experiment mice were divided into two groups, control (room condition, Kathmandu, Nepal) and hypoxic (hypoxic condition). For conditioning, the hypoxic group was exposed to lower levels of hypobaric hypoxia during our mountaineering expedition to Mt Everest. The oxygen level was decreased according to our climbing protocol from 21% to about 7% over a period of 15 days. Food and water were changed daily during the course of the experiment. After 15 days animals were euthanized after whole blood extraction from V. Cava for further analysis. RNA from whole blood was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at control versus hypobaric hypoxia in whole blood using a false discovery rate (FDR) of 0%.We validated the profiles by real-time quantitative reverse transcription-polymerase chain reaction (qPCR). Results: The regional transcriptomes associated with hypobaric hypoxia on Mt. Everest in whole blood were identified. We found 947 genes that were differentially expressed in normobaric hypoxic whole blood compared to control with a 0% FDR and a 2 fold cutoff. Conclusion: Transcriptome level differences exist between control and hypobaric hypoxia in whole blood. Our definition of the synaptic transcriptome provides insight into the functioning of the unique response to hypoxia in whole blood.
2010-05-07 | E-GEOD-15901 | biostudies-arrayexpress
Project description:To understand hypoxia mediated changes in whole blood, normal C57Bl/10 mice were gradually exposed to a chronic chemical hypoxic environment, for 2 weeks. Control, age-machted mice were maintained under normoxic conditions. Purpose: To examine and characterize the expression profile of genes expressed at chemical hypoxia of whole blood in comparison to the control. Methods: At the beginning of the experiment mice were divided into two groups, control (room condition) and chemical hypoxic (room condition). For conditioning, the chemical hypoxic group was supplemented with 200ng of CoCl2 per 100ml/day. Animalâs weight and food intake were monitored daily. Food and water were changed daily during the course of the experiment. Before and after the experiments the hematocrit was monitored by taking blood from the tail vein of control and hypoxic animals. After 15 days animals were euthanized using CO2 after whole blood extraction from V. Cava for further analysis. RNA from whole blood was isolated, processed and used for microarray-based expression profiling. Profiles were generated for genes differentially expressed at control versus chemical hypoxia in whole blood using a false discovery rate (FDR) of 0%.We validated the profiles by real-time quantitative reverse transcription-polymerase chain reaction (qPCR). Results: The regional transcriptomes associated with chemical hypoxia in whole blood were identified. We found 3094 genes that were differentially expressed in chemical hypoxic whole blood compared to control with a 0% FDR and a 2 fold cutoff. Conclusion: Transcriptome level differences exist between control and chemical hypoxia in whole blood. Our definition of the synaptic transcriptome provides insight into the functioning of the unique response to hypoxia in whole blood.
2010-05-07 | E-GEOD-15902 | biostudies-arrayexpress