Integration of TRPC6 and NADPH oxidase activation in lysophosphatidylcholine-induced TRPC5 externalization

Lipid oxidation products, including lysophosphatidylcholine (lysoPC), activate canonical transient receptor potential 6 (TRPC6) channels, and the subsequent increase in intracellular Ca2+ leads to TRPC5 activation. The goal of this study is to elucidate the steps in the pathway between TRPC6 activation and TRPC5 externalization. Following TRPC6 activation by lysoPC, extracellular regulated kinase (ERK) is phosphorylated. This leads to phosphorylation of p47phox and subsequent NADPH oxidase activation with increased production of reactive oxygen species. ERK activation requires TRPC6 opening and influx of Ca2+ as evidenced by the failure of lysoPC to induce ERK phosphorylation in TRPC6−/− endothelial cells. ERK siRNA blocks the lysoPC-induced activation of NADPH oxidase, demonstrating that ERK activation is upstream of NADPH oxidase. The reactive oxygen species produced by NADPH oxidase promote myosin light chain kinase (MLCK) activation with phosphorylation of MLC and TRPC5 externalization. Downregulation of ERK, NADPH oxidase, or MLCK with the relevant siRNA prevents TRPC5 externalization. Blocking MLCK activation prevents the prolonged rise in intracellular calcium levels and preserves endothelial migration in the presence of lysoPC.

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Cell signalling by oxidized lipids and the role of reactive oxygen species in the endothelium

Biochemical Society Transactions ◽

10.1042/bst0331385 ◽

2005 ◽

Vol 33 (6) ◽

pp. 1385-1389 ◽

Cited By ~ 43

Author(s):

J.W. Zmijewski ◽

A. Landar ◽

N. Watanabe ◽

D.A. Dickinson ◽

N. Noguchi ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Lipid Oxidation ◽

Protein Function ◽

Cell Signalling ◽

Reactive Oxygen ◽

Oxidation Products ◽

Oxidized Lipids ◽

Oxygen Species ◽

Post Translational Modification ◽

Lipid Oxidation Products

The controlled formation of ROS (reactive oxygen species) and RNS (reactive nitrogen species) is now known to be critical in cellular redox signalling. As with the more familiar phosphorylation-dependent signal transduction pathways, control of protein function is mediated by the post-translational modification at specific amino acid residues, notably thiols. Two important classes of oxidant-derived signalling molecules are the lipid oxidation products, including those with electrophilic reactive centres, and decomposition products such as lysoPC (lysophosphatidylcholine). The mechanisms can be direct in the case of electrophiles, as they can modify signalling proteins by post-translational modification of thiols. In the case of lysoPC, it appears that secondary generation of ROS/RNS, dependent on intracellular calcium fluxes, can cause the secondary induction of H2O2 in the cell. In either case, the intracellular source of ROS/RNS has not been defined. In this respect, the mitochondrion is particularly interesting since it is now becoming apparent that the formation of superoxide from the respiratory chain can play an important role in cell signalling, and oxidized lipids can stimulate ROS formation from an undefined source. In this short overview, we describe recent experiments that suggest that the cell signalling mediated by lipid oxidation products involves their interaction with mitochondria. The implications of these results for our understanding of adaptation and the response to stress in cardiovascular disease are discussed.

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Interaction of electrophilic lipid oxidation products with mitochondria in endothelial cells and formation of reactive oxygen species

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.01087.2005 ◽

2006 ◽

Vol 290 (5) ◽

pp. H1777-H1787 ◽

Cited By ~ 95

Author(s):

Aimee Landar ◽

Jaroslaw W. Zmijewski ◽

Dale A. Dickinson ◽

Claire Le Goffe ◽

Michelle S. Johnson ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Endothelial Cells ◽

Reactive Oxygen ◽

Direct Interaction ◽

Oxidation Products ◽

Antioxidant Defenses ◽

Heme Oxygenase 1 ◽

Oxygen Species ◽

Lipid Oxidation Products ◽

Ros Formation

Electrophilic lipids, such as 4-hydroxynonenal (HNE), and the cyclopentenones 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and 15-J2-isoprostane induce both reactive oxygen species (ROS) formation and cellular antioxidant defenses, such as heme oxygenase-1 (HO-1) and glutathione (GSH). When we compared the ability of these distinct electrophiles to stimulate GSH and HO-1 production, the cyclopentenone electrophiles were somewhat more potent than HNE. Over the concentration range required to observe equivalent induction of GSH, dichlorofluorescein fluorescence was used to determine both the location and amounts of electrophilic lipid-dependent ROS formation in endothelial cells. The origin of the ROS on exposure to these compounds was largely mitochondrial. To investigate the possibility that the increased ROS formation was due to mitochondrial localization of the lipids, we prepared a novel fluorescently labeled form of the electrophilic lipid 15d-PGJ2. The lipid demonstrated strong colocalization with the mitochondria, an effect which was not observed by using a fluorescently labeled nonelectrophilic lipid. The role of mitochondria was confirmed by using cells deficient in functional mitochondria. On the basis of these data, we propose that ROS formation in endothelial cells is due to the direct interaction of these lipids with the organelle.

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NADPH Oxidase Activation Is Required in Reactive Oxygen Species Generation and Cell Transformation Induced by Hexavalent Chromium

Toxicological Sciences ◽

10.1093/toxsci/kfr180 ◽

2011 ◽

Vol 123 (2) ◽

pp. 399-410 ◽

Cited By ~ 62

Author(s):

Xin Wang ◽

Young-Ok Son ◽

Qingshan Chang ◽

Lijuan Sun ◽

J.Andrew Hitron ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Nadph Oxidase ◽

Hexavalent Chromium ◽

Cell Transformation ◽

Reactive Oxygen Species Generation ◽

Reactive Oxygen ◽

Oxygen Species ◽

Nadph Oxidase Activation

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Scavenging Reactive Lipids to Prevent Oxidative Injury

The Annual Review of Pharmacology and Toxicology ◽

10.1146/annurev-pharmtox-031620-035348 ◽

2021 ◽

Vol 61 (1) ◽

pp. 291-308 ◽

Cited By ~ 1

Author(s):

Linda S. May-Zhang ◽

Annet Kirabo ◽

Jiansheng Huang ◽

MacRae F. Linton ◽

Sean S. Davies ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Host Defense ◽

Reactive Oxygen ◽

Oxidative Injury ◽

Oxidation Products ◽

Oxygen Species ◽

The Past ◽

Lipid Oxidation Products ◽

Induce Lipid Peroxidation

Oxidative injury due to elevated levels of reactive oxygen species is implicated in cardiovascular diseases, Alzheimer's disease, lung and liver diseases, and many cancers. Antioxidant therapies have generally been ineffective at treating these diseases, potentially due to ineffective doses but also due to interference with critical host defense and signaling processes. Therefore, alternative strategies to prevent oxidative injury are needed. Elevated levels of reactive oxygen species induce lipid peroxidation, generating reactive lipid dicarbonyls. These lipid oxidation products may be the most salient mediators of oxidative injury, as they cause cellular and organ dysfunction by adducting to proteins, lipids, and DNA. Small-molecule compounds have been developed in the past decade to selectively and effectively scavenge these reactive lipid dicarbonyls. This review outlines evidence supporting the role of lipid dicarbonyls in disease pathogenesis, as well as preclinical data supporting the efficacy of novel dicarbonyl scavengers in treating or preventing disease.

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