11 results on '"Opdenakker, Kelly"'
Search Results
2. Unraveling uranium induced oxidative stress related responses in Arabidopsis thaliana seedlings. Part II: responses in the leaves and general conclusions
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Vanhoudt, Nathalie, Cuypers, Ann, Horemans, Nele, Remans, Tony, Opdenakker, Kelly, Smeets, Karen, Bello, Daniel Martinez, Havaux, Michel, Wannijn, Jean, Van Hees, May, Vangronsveld, Jaco, and Vandenhove, Hildegarde
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- 2011
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3. Unraveling uranium induced oxidative stress related responses in Arabidopsis thaliana seedlings. Part I: responses in the roots
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Vanhoudt, Nathalie, Vandenhove, Hildegarde, Horemans, Nele, Remans, Tony, Opdenakker, Kelly, Smeets, Karen, Bello, Daniel Martinez, Wannijn, Jean, Van Hees, May, Vangronsveld, Jaco, and Cuypers, Ann
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- 2011
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4. Cadmium stress: an oxidative challenge
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Cuypers, Ann, Plusquin, Michelle, Remans, Tony, Jozefczak, Marijke, Keunen, Els, Gielen, Heidi, Opdenakker, Kelly, Nair, Ambily Ravindran, Munters, Elke, Artois, Tom J., Nawrot, Tim, Vangronsveld, Jaco, and Smeets, Karen
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- 2010
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5. The role of the kinase OXI1 in cadmium- and copper-induced molecular responses in Arabidopsis thaliana.
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SMEETS, KAREN, OPDENAKKER, KELLY, REMANS, TONY, FORZANI, CELINE, HIRT, HERIBERT, VANGRONSVELD, JACO, and CUYPERS, ANN
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MITOGEN-activated protein kinases , *EFFECT of cadmium on plants , *SUPEROXIDE dismutase , *OXYLIPINS , *EFFECT of copper on plants , *LIPOXYGENASES , *PLANT defenses - Abstract
The hypothesis that mitogen-activated protein kinase ( MAPK) signalling is important in plant defences against metal stress has become accepted in recent years. To test the role of oxidative signal-inducible kinase ( OXI1) in metal-induced oxidative signalling, the responses of oxi1 knockout lines to environmentally realistic cadmium ( Cd) and copper ( Cu) concentrations were compared with those of wild-type plants. A relationship between OXI1 and the activation of lipoxygenases and other initiators of oxylipin production was observed under these stress conditions, suggesting that lipoxygenase-1 may be a downstream component of OXI1 signalling. Metal-specific differences in OXI1 action were observed. For example, OXI1 was required for the up-regulation of antioxidative defences such as catalase in leaves and Fe-superoxide dismutase in roots, following exposure to Cu, processes that may involve the MEKK1- MKK2- WRKY25 cascade. Moreover, the induction of Cu/Zn superoxide dismutases in Cu-exposed leaves was regulated by OXI1 in a manner that involves fluctuations in the expression of miRNA398. These observations contrast markedly with the responses to Cd exposure, which also involves OXI1-independent pathways but rather involves changes in components mediating intracellular communication. [ABSTRACT FROM AUTHOR]
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- 2013
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6. Exposure of Arabidopsis thaliana to excess Zn reveals a Zn-specific oxidative stress signature
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Remans, Tony, Opdenakker, Kelly, Guisez, Yves, Carleer, Robert, Schat, Henk, Vangronsveld, Jaco, and Cuypers, Ann
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ARABIDOPSIS thaliana , *ZINC content of plants , *OXIDATIVE stress , *PLANT nutrition , *OXIDATION-reduction reaction , *HOMEOSTASIS , *GLUTATHIONE , *MICRORNA - Abstract
Abstract: Zinc (Zn) is an essential micronutrient for plants, but accumulation of excess Zn causes oxidative stress, even though the element is not redox-active. An oxidative stress signature, consisting of multiple oxidative stress related parameters, is indicative of disturbance of redox homeostasis and signaling, but has not been determined after exposure to excess Zn. To reveal general and Zn-specific effects, changes in oxidative stress related gene expression, enzyme activities and metabolites were determined after 24h exposure of Arabidopsis thaliana plants to a concentration range of 0, 100, 250 or 500μM excess ZnSO4, and the oxidative stress signature compared to the ones reported previously for cadmium or copper exposure in the same experimental system. Zn accumulated in both roots and leaves, which led to a disturbed redox homeostasis as evident from increased H2O2 levels and altered glutathione redox state. In roots, magnesium uptake was affected and glutathione levels decreased due to reduced glutathione reductase activity and increased phytochelatin production. In leaves, mRNA levels of all chloroplast-localized superoxide dismutases (SOD) were downregulated, indicating that the converse regulation by Cu availability of FeSOD (FSD) and Cu/ZnSOD genes (CSDs) was disturbed. Furthermore, an opposite stress-dependent transcriptional regulation of the different loci of a miRNA species was observed: excess Zn repressed primary transcripts of the MIR398a gene, but increased MIR398b and MIR398c transcription. Also, accumulation of mRNA was inhibited for CSD2, but stimulated for CSD1. MiR398 has been reported to downregulate CSD1 and CSD2 mRNA. Here, the opposite effect on CSD1 and CSD2 mRNA accumulation under Zn stress in the leaves could be explained if CSD1 in the leaves would be regulated exclusively by miR398a, and not by miR398b/c under these conditions. The results support the existence of Zn-specific signal transduction pathways influencing anti-oxidative responses and are useful as a starting point for genetic screens identifying upstream metal-specific sensing and signaling mechanisms. [Copyright &y& Elsevier]
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- 2012
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7. Exposure of Arabidopsis thaliana to Cd or Cu excess leads to oxidative stress mediated alterations in MAPKinase transcript levels
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Opdenakker, Kelly, Remans, Tony, Keunen, Els, Vangronsveld, Jaco, and Cuypers, Ann
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ARABIDOPSIS thaliana , *PHYSIOLOGICAL effects of cadmium , *CADMIUM poisoning , *PHYSIOLOGICAL effects of copper , *EFFECT of metals on plants , *PLANTS , *OXIDATIVE stress , *MITOGEN-activated protein kinases , *REACTIVE oxygen species , *PLANT species - Abstract
Abstract: Metals, like cadmium (Cd) and copper (Cu), have the ability to induce the production of reactive oxygen species (ROS) at the cellular level. It is widely known that these ROS can cause irreversible damage to cellular components, like DNA, proteins and lipids. On the other hand, ROS can also act as signaling molecules and in this way they play an essential role in many normal physiological processes, but also in defense responses against stress. ROS signaling in plants uses mitogen-activated protein kinase (MAPK) pathways leading to the transcriptional control of target genes involved in the scavenging or production of ROS. Here, oxidative signaling induced by exposure to excess Cd or Cu was investigated in relation to anti-oxidative defense responses to these metals. Three-week-old Arabidopsis thaliana plants were exposed to environmentally realistic concentrations of Cu and Cd and immediate responses were measured at the level of hydrogen peroxide (H2O2) content, lipid peroxidation and transcript levels of genes involved in ROS homeostasis and signaling. Our findings show immediate (after 2h exposure) effects in the roots following Cu exposure, whereas effects in the leaves were generally more delayed. Effects of Cd exposure in leaves and roots were observed only after 24h exposure. On one hand, exposure of roots to Cu leads via activation of NADPH oxidases and Fenton reactions to H2O2 production that can induce MAPK and oxylipin signaling to control the cellular redox status. On the other hand, conversion of H2O2 to the more damaging hydroxyl radical by Fenton and Haber–Weiss reactions can initiate lipid peroxidation leading to membrane damage. In roots exposed to elevated Cd concentrations only oxidative signaling was initiated, possibly via NADPH oxidase-mediated ROS production. In leaves, time-dependent activation of MAPK and oxylipin signaling was seen after exposure to both metals, Cu or Cd, independent of changes in H2O2 content. [Copyright &y& Elsevier]
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- 2012
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8. Mitogen-Activated Protein (MAP) Kinases in Plant Metal Stress: Regulation and Responses in Comparison to Other Biotic and Abiotic Stresses.
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Opdenakker, Kelly, Remans, Tony, Vangronsveld, Jaco, and Cuypers, Ann
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MITOGEN-activated protein kinases , *EFFECT of metals on plants , *REACTIVE oxygen species , *PHOSPHATASES , *ETHYLENE , *JASMONIC acid - Abstract
Exposure of plants to toxic concentrations of metals leads to disruption of the cellular redox status followed by an accumulation of reactive oxygen species (ROS). ROS, like hydrogen peroxide, can act as signaling molecules in the cell and induce signaling via mitogen-activated protein kinase (MAPK) cascades. MAPK cascades are evolutionary conserved signal transduction modules, able to convert extracellular signals to appropriate cellular responses. In this review, our current understanding about MAPK signaling in plant metal stress is discussed. However, this knowledge is scarce compared to research into the role of MAPK signaling in the case of other abiotic and biotic stresses. ROS production is a common response induced by different stresses and undiscovered analogies may exist with metal stress. Therefore, further attention is given to MAPK signaling in other biotic and abiotic stresses and its interplay with other signaling pathways to create a framework in which the involvement of MAPK signaling in metal stress may be studied. [ABSTRACT FROM AUTHOR]
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- 2012
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9. Oxidative stress-related responses at transcriptional and enzymatic levels after exposure to Cd or Cu in a multipollution context
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Smeets, Karen, Opdenakker, Kelly, Remans, Tony, Van Sanden, Suzy, Van Belleghem, Frank, Semane, Brahim, Horemans, Nele, Guisez, Yves, Vangronsveld, Jaco, and Cuypers, Ann
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OXIDATIVE stress , *ENZYMATIC analysis , *PHYSIOLOGICAL effects of copper , *PHYSIOLOGICAL effects of cadmium , *LIPID peroxidation (Biology) , *LIPOXYGENASES , *GENE expression , *ARABIDOPSIS thaliana - Abstract
Summary: The physiological effects of Cd and Cu have been highlighted in several studies over the last years. At the cellular level, oxidative stress has been reported as a common mechanism in both stress situations. Nevertheless, because of differences in their redox-related properties, the origin of the stress and regulation of these effects can be very different. Our results show a specific Cd-related induction of NADPH oxidases, whereas both metals induced lipid peroxidation via the activation of lipoxygenases. With respect to the antioxidative defense system, metal-specific patterns of superoxide dismutases (SODs) were detected, whereas gene expression levels of the H2O2-quenching enzymes were equally induced by both metals. Because monometallic exposure is very unusual in real-world situations, the metal-specific effects were compared with the mechanisms induced when the plants are exposed to both metals simultaneously. Combined exposure to Cd and Cu enhanced some of the effects that were induced when only one metal was applied to the medium. Other specific monometallically induced effects, such as a copper zinc superoxide dismutase (CSD2) downregulation due to Cd, were also sustained in a multipollution context, irrespective of the other monometallic effects. Furthermore, specific multipollution effects were unravelled, as iron superoxide dismutase 1 (FSD1) upregulation in the leaves was significant only when both Cu and Cd were applied. Additional relationships between these treatments and the common and specific stress induction mechanisms are discussed. [Copyright &y& Elsevier]
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- 2009
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10. A mutant of the Arabidopsis thaliana LIPOXYGENASE1 gene shows altered signalling and oxidative stress related responses after cadmium exposure
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Keunen, Els, Remans, Tony, Opdenakker, Kelly, Jozefczak, Marijke, Gielen, Heidi, Guisez, Yves, Vangronsveld, Jaco, and Cuypers, Ann
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ARABIDOPSIS thaliana genetics , *PLANT mutation , *PLANT cellular signal transduction , *PLANTS , *OXIDATIVE stress , *EFFECT of cadmium on plants , *LIPOXYGENASES , *PLANT growth , *PLANT development - Abstract
Abstract: Lipoxygenases (LOXes, EC 1.13.11.12) are involved in growth, development and responses to stress. Earlier results suggested a role in stress generation, signalling and/or responses when Arabidopsis thaliana is exposed to cadmium (Cd), and expression of the cytosolic LOX1 was highly upregulated in the roots after Cd exposure. To investigate the involvement of LOX1 in early metal stress responses, three-week-old wild-type and lox1-1 mutant A. thaliana plants were acutely (24 h) exposed to realistic Cd concentrations (5 and 10 μM) and several oxidative stress and signalling related parameters were studied at transcriptional and biochemical levels. Transcription of several genes encoding ROS producing and scavenging enzymes failed to be induced up to wild-type levels after Cd exposure. Expression of 9-LOX enzymes was inhibited in lox1-1 mutant roots due to lack of functional LOX1 and downregulated LOX5 expression, and the lox1-1 mutation also interfered with the expression of genes involved in jasmonate biosynthesis. LOX1 and RBOHD may be involved in stress signalling from roots to shoots, as the induction of APX2 expression, which is dependent on RBOHD activity, was disrupted in lox1-1 while RBOHD failed to be upregulated. A different pattern of H2O2 production and ascorbate and glutathione levels in lox1-1 mutants after Cd exposure may have indirectly influenced gene expression patterns. Although indirect effects of the lox1-1 mutation on gene expression complicate the determination of exact sensing – signalling – response pathways, the results presented here outline a more refined LOX1 functioning in Cd-induced stress responses that could be used in studies determining the exact involvement of LOX1 in these pathways. [Copyright &y& Elsevier]
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- 2013
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11. The cellular redox state as a modulator in cadmium and copper responses in Arabidopsis thaliana seedlings.
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Cuypers A, Smeets K, Ruytinx J, Opdenakker K, Keunen E, Remans T, Horemans N, Vanhoudt N, Van Sanden S, Van Belleghem F, Guisez Y, Colpaert J, and Vangronsveld J
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- Arabidopsis enzymology, Arabidopsis metabolism, Cadmium metabolism, Copper metabolism, Gene Expression drug effects, Gene Expression Regulation, Plant, Genes, Plant genetics, Hydrogen Peroxide metabolism, Lipid Peroxidation, Models, Biological, Oxidation-Reduction, Oxidative Stress drug effects, Plant Leaves drug effects, Plant Leaves metabolism, Plant Proteins genetics, Plant Proteins metabolism, Plant Roots drug effects, Plant Roots metabolism, Reactive Oxygen Species metabolism, Seedlings enzymology, Seedlings metabolism, Signal Transduction, Stress, Physiological, Arabidopsis drug effects, Cadmium pharmacology, Copper pharmacology, Oxidative Stress physiology, Seedlings drug effects
- Abstract
The cellular redox state is an important determinant of metal phytotoxicity. In this study we investigated the influence of cadmium (Cd) and copper (Cu) stress on the cellular redox balance in relation to oxidative signalling and damage in Arabidopsis thaliana. Both metals were easily taken up by the roots, but the translocation to the aboveground parts was restricted to Cd stress. In the roots, Cu directly induced an oxidative burst, whereas enzymatic ROS (reactive oxygen species) production via NADPH oxidases seems important in oxidative stress caused by Cd. Furthermore, in the roots, the glutathione metabolism plays a crucial role in controlling the gene regulation of the antioxidative defence mechanism under Cd stress. Metal-specific alterations were also noticed with regard to the microRNA regulation of CuZnSOD gene expression in both roots and leaves. The appearance of lipid peroxidation is dual: it can be an indication of oxidative damage as well as an indication of oxidative signalling as lipoxygenases are induced after metal exposure and are initial enzymes in oxylipin biosynthesis. In conclusion, the metal-induced cellular redox imbalance is strongly dependent on the chemical properties of the metal and the plant organ considered. The stress intensity determines its involvement in downstream responses in relation to oxidative damage or signalling., (Copyright © 2010 Elsevier GmbH. All rights reserved.)
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- 2011
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