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. Arabidopsis Affymetrix GeneChip arrays were probed with RNAs isolated from leaves of untreated plants (controls) and plants upon hypoxia under light submergence for 48 h.
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.
Project description:Flooded plants experience impaired gas diffusion underwater, leading to oxygen deprivation (hypoxia) stress. The volatile plant hormone ethylene is rapidly trapped in submerged plant cells and is instrumental for enhanced metabolic hypoxia acclimation. However, the precise mechanisms underpinning ethylene-enhanced hypoxia survival remain unclear. We studied the effect of ethylene pre-treatment on hypoxia survival of primary Arabidopsis thaliana root tips.
Project description:Friedreich’s Ataxia (FRDA) is an autosomal neurodegenerative disease caused by the deficiency of protein frataxin. Frataxin functions in the assembly of iron-sulfur clusters that are important for iron homeostasis and metabolic functions. To identify metabolic features that can be used for potential biomarkers in FRDA plasma, we performed a targeted multi-omics (metabolomics, lipidomics, and proteomics) analysis using discovery-validation cohort design. Muti-omics analysis revealed that FRDA patients had dysregulated sphingolipid metabolism, phospholipid metabolism, citric acid cycle, amino acid metabolism, and apolipoprotein metabolism. Sphingolipid dysfunctions were revealed by decreased very long chain ceramides but unchanged long chain ceramides in FRDA plasma, which resulted in the increased ratio of long chain ceramides to very long chain ceramides. Decreased very long chain ceramides distinguished FRDA patients from healthy controls and showed good predictive capacities with AUC values from 0.75 to 0.85. Furthermore, by performing lipidomic and stable isotope tracing experiment in induced pluripotent stem cell differentiated cardiomyocytes (iPSC-CMs, we demonstrated that frataxin deficiency affected ceramide synthase (CerS2), and preferentially enriched long chain ceramides and depleted very long chain ceramides. Moreover, ceramide metabolism was differentially regulated in a tissue-specific manner. Finally, machine learning model increased the prediction of FRDA using the combination of three metabolites (AUC > 0.9). In conclusion, decreased very long chain ceramides are potential biomarkers and therapeutic target in FRDA patients.
Project description:Friedreich’s Ataxia (FRDA) is an autosomal neurodegenerative disease caused by the deficiency of protein frataxin. Frataxin functions in the assembly of iron-sulfur clusters that are important for iron homeostasis and metabolic functions. To identify metabolic features that can be used for potential biomarkers in FRDA plasma, we performed a targeted multi-omics (metabolomics, lipidomics, and proteomics) analysis using discovery-validation cohort design. Muti-omics analysis revealed that FRDA patients had dysregulated sphingolipid metabolism, phospholipid metabolism, citric acid cycle, amino acid metabolism, and apolipoprotein metabolism. Sphingolipid dysfunctions were revealed by decreased very long chain ceramides but unchanged long chain ceramides in FRDA plasma, which resulted in the increased ratio of long chain ceramides to very long chain ceramides. Decreased very long chain ceramides distinguished FRDA patients from healthy controls and showed good predictive capacities with AUC values from 0.75 to 0.85. Furthermore, by performing lipidomic and stable isotope tracing experiment in induced pluripotent stem cell differentiated cardiomyocytes (iPSC-CMs, we demonstrated that frataxin deficiency affected ceramide synthase (CerS2), and preferentially enriched long chain ceramides and depleted very long chain ceramides. Moreover, ceramide metabolism was differentially regulated in a tissue-specific manner. Finally, machine learning model increased the prediction of FRDA using the combination of three metabolites (AUC > 0.9). In conclusion, decreased very long chain ceramides are potential biomarkers and therapeutic target in FRDA patients.
Project description:Analysis of tamoxifen-sensitivity recovery effect by genes which are regulated by ELOVL2(Elongation of very long chain fatty acids protein 2) at gene expression level in breast cancer. This study identifies that ELOVL2 regulates AKT or ER signaling-related genes and ELOVL2 as an essential gene responsible for resistance.
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.
Project description:A life-essential function of the epidermis is to provide a physical barrier that prevents the loss of water and electrolytes. Essential mediators of this permeability barrier function include ceramides, cholesterol and very long chain fatty acids. Accordingly, their alteration may lead to distinct human conditions, including psoriasis or atopic dermatitis. Recently, a frameshift mutation in the human ZNF750 gene, that encodes for a zinc finger transcription factor, causing a seborrhea-like dermatitis with psoriasiform element, has brought ZNF750 as a key element for the maintenance of the epidermal tissue homeostasis. To clarify this hypothesis, with its underlying molecular mechanism, we generated a novel mouse knockout by deleting exon 2. Here, we show that genetic deletion of the mouse homolog ZFP750 results in loss of epidermal permeability barrier function. ZFP750-/- mice die shortly after birth, within 12 hours. In the stratum corneum of ZFP750-/- mice levels of ceramides, nonpolar lipids and intercellular lipid lamellae are significantly reduced. The alteration of the epidermal lipid homeostasis is directly linked to the transcriptional activity of ZFP750. Indeed, in addition to epidermal differentiation genes, ZFP750 directly and/or indirectly regulates the expression of nearly 50 crucial enzymes in the biosynthesis of ceramides, such as SPTLC1, DGAT2, SMPD3, ELOVL7 and DEGS2. Overall, our study identifies the transcription factor ZFP750 as a master regulator of lipid biosynthesis and epidermal homeostasis and may contribute to our understanding of the pathogenesis of several human skin diseases.
Project description:Aerenchyma is a specialized tissue consisting of longitudinal gas spaces, which enables internal movement of gases (e.g., O2, CO2, ethylene and methane), in plant roots, petioles and stems. Especially, internal transport of oxygen via aerenchyma from shoots to roots is very important for adaptation or survival of plants under waterlogged condition. To identify aerenchyma formation-associated genes expressed in maize root, we used LM combined with a microarray for monitoring genes expressed in root cortical cells under three conditions: under aerobic condition and under waterlogged condition with and without pretreatment with 1-MCP, an inhibitor of ethylene perception. For the waterlogging treatments, the primary root (but not the shoots) was waterlogged. Two and half day-old-seedlings were pre-treated with an inhibitor of ethylene perception 1-methylcyclopropene (1-MCP; 1 ppm) for 12 hours before the waterlogging treatment. Three-day-old seedlings were growing under aerated condition at the same time with other treatments as a control. Total RNA was extracted from root cortex cells from the segment of the primary root, 0.5 cm long: from 1.5 to 2 cm from the junction shoot-root derived from 3-days-old maize seedlings, and subjected to 44k oligo-DNA microarray (1. Aerated vs Hypoxia, 2. Hypoxia+MCP vs Hypoxia) with 3 biological replicates and color swaps.
Project description:Background: Polycyclic aromatic hydrocarbons (PAHs) are toxic, widely-distributed, environmentally persistent, and carcinogenic byproducts of carbon-based fuel combustion. Previously, plant studies have shown that PAHs induce oxidative stress, reduce growth, and cause leaf deformation as well as tissue necrosis. To understand the transcriptional changes that occur during these processes, we performed microarray experiments on Arabidopsis thaliana L. under phenanthrene treatment, and compared the results to published Arabidopsis microarray data representing a variety of stress and hormone treatments. In addition, to probe hormonal aspects of PAH stress, we assayed transgenic ethylene-inducible reporter plants as well as ethylene pathway mutants under phenanthrene treatment. Results: Microarray results revealed numerous perturbations in signaling and metabolic pathways that regulate reactive oxygen species (ROS) and responses related to pathogen defense. A number of glutathione S-transferases that may tag xenobiotics for transport to the vacuole were upregulated. Comparative microarray analyses indicated that the phenanthrene response was closely related to other ROS conditions, including pathogen defense conditions. The ethylene-inducible transgenic reporters were activated by phenanthrene. Mutant experiments showed that PAH inhibits growth through an ethylene-independent pathway, as PAH-treated ethylene-insensitive etr1-4 mutants exhibited a greater growth reduction than WT. Further, phenanthrene-treated, constitutive ethylene signaling mutants had longer roots than the untreated control plants, indicating that the PAH inhibits parts of the ethylene signaling pathway. Conclusions: This study identified major physiological systems that participate in the PAH-induced stress response in Arabidopsis. At the transcriptional level, the results identify specific gene targets that will be valuable in finding lead compounds and engineering increased tolerance. Collectively, the results open a number of new avenues for researching and improving plant resilience and PAH phytoremediation. Arabidopsis thaliana (ecotype Columbia) plants were long-day grown with +/- 0.25 mM phenanthrene in sterile plates at 23C for 21d before harvest. At least 20 plants were pooled prior to each mRNA extraction.