Excessive Copper Induces the Production of Reactive Oxygen Species, which is Mediated by Phospholipase D, Nicotinamide Adenine Dinucleotide Phosphate Oxidase and Antioxidant Systems

Abstract

Tobacco BY-2 suspension cells were used to study the chemical damage and its associated mechanisms caused by Cu2+. Treatment with 100 micromol/L Cu2+ generated a large amount of H2O2 and thiobarbituric acid-reactive substances (TBARS) in cells. Using phospholipase D (PLD) specific inhibitor (1-butanol) or phosphatidic acid (PA), we demonstrated that PLD plays an important role in the generation of H2O2 and TBARS. Semi-quantitative reverse-transcriptase polymerase chain reaction and enzyme activity assays with wild type and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-overexpressing BY-2 cells revealed that PLD and PA are the key factors leading to NADPH oxidase activation, which is responsible for H2O2 and TBARS production induced by Cu2+. Moreover, the content of ascorbic acid (AsA), an effective antioxidant, was sharply reduced in BY-2 cells exposed to excessive Cu2+. Furthermore, a significant downregulation of the enzymes of AsA biosynthesis and the antioxidant system was found. This evidence suggests that excessive Cu2+-elevated reactive oxygen species (ROS) production is caused by upregulated PLD that elevates the activity of NADPH oxidase and its collapsed antioxidant systems that scavenges ROS.

Ozone sensing and early signaling in plants: An outline from the cloud

“…PA exhibits different modes of action (Wang et al, 2006). For our present concern, it is particularly notable that PLD-produced PA can induce ROS production by enhancing NADPH oxidase activity (Yu et al, 2008;Zhang et al, 2009) or regulate mitogen-activated protein kinases (MAPKs) indirectly (Lee et al, 2001;Im et al, 2012a,b), or directly, like AtMPK6 (Yu et al, 2010). This point is particularly interesting, as AtMPK6, an Arabidopsis MAPK and a stress-signaling component, is activated under O 3 (Ahlfors et al, 2004).…”

“…This point is particularly interesting, as AtMPK6, an Arabidopsis MAPK and a stress-signaling component, is activated under O 3 (Ahlfors et al, 2004). Moreover, only specific PA species (e.g., 16:0-18:2 PAs) bind AtMPK6 (Yu et al, 2008) or activate NADPH oxidase (Zhang et al, 2009). This could suggest stress-response specificity of PA signaling.…”

Exogenously induced expression of ethylene biosynthesis, ethylene perception, phospholipase D, and Rboh-oxidase genes in broccoli seedlings

“…The enhanced activity of Rboh-NADPH oxidase and also an essential accumulation of H 2 O 2 in the plasma membrane and cell walls in response to copper have been shown in different species (Quartacci et al , 2001; Yu et al , 2008; Zhang et al , 2008; Wu et al , 2009). Copper-induced oxidative stress results, first, from the directly catalysed formation of ROS via a Fenton-like reaction and, secondly, from a significantly decreased glutathione (GSH) level by copper ions.…”

“…It has been assumed that PA PLD can enhance the activity of Rboh-NADPH-oxidase (Yu et al , 2008). A direct promotion of the catalytical activity of Rboh-oxidase by PLD-α1-derived PA species and the Cu 2+ -induced elevation of both PA PLD content and activation of Rboh-oxidase have been found in Arabidopsis (Zhang et al , 2005) and wheat (Navari-Izzo et al , 2006).…”

Desbalanço redox: NADPH oxidase como um alvo terapêutico no manejo cardiovascular

“…Some of these environment pollutants are capable of increasing the production of free radicals by means of activation of enzyme complex NADPH oxidase 43,44 , and this mechanism may be seen as probable cause of high blood pressure induced by said chemical species.…”