title: Redox-active antioxidant modulation of lipid signaling in vascular endothelial cells: vitamin C induces activation of phospholipase D through phospholipase A2, lipoxygenase, and cyclooxygenase.
abstract: We have earlier reported that the redox-active antioxidant, vitamin C (ascorbic acid), activates the lipid signaling enzyme, phospholipase D (PLD), at pharmacological doses (mM) in the bovine lung microvascular endothelial cells (BLMVECs). However, the activation of phospholipase A(2) (PLA(2)), another signaling phospholipase, and the modulation of PLD activation by PLA(2) in the ECs treated with vitamin C at pharmacological doses have not been reported to date. Therefore, this study aimed at the regulation of PLD activation by PLA(2) in the cultured BLMVECs exposed to vitamin C at pharmacological concentrations. The results revealed that vitamin C (3-10 mM) significantly activated PLA(2) starting at 30 min; however, the activation of PLD resulted only at 120 min of treatment of cells under identical conditions. Further studies were conducted utilizing specific pharmacological agents to understand the mechanism(s) of activation of PLA(2) and PLD in BLMVECs treated with vitamin C (5 mM) for 120 min. Antioxidants, calcium chelators, iron chelators, and PLA(2) inhibitors offered attenuation of the vitamin C-induced activation of both PLA(2) and PLD in the cells. Vitamin C was also observed to significantly induce the formation and release of the cyclooxygenase (COX)- and lipoxygenase (LOX)-catalyzed arachidonic acid (AA) metabolites and to activate the AA LOX in BLMVECs. The inhibitors of PLA(2), COX, and LOX were observed to effectively and significantly attenuate the vitamin C-induced PLD activation in BLMVECs. For the first time, the results of the present study revealed that the vitamin C-induced activation of PLD in vascular ECs was regulated by the upstream activation of PLA(2), COX, and LOX through the formation of AA metabolites involving oxidative stress, calcium, and iron.
authors.affiliation: Lipid Signaling and Lipidomics Laboratory, Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine, Department of Medicine, College of Medicine, The Ohio State University, Columbus, OH, USA.
authors.forename: Emily
authors.initials: E
authors.lastname: Steinhour
authors.forename: Shariq I
authors.initials: SI
authors.lastname: Sherwani
authors.forename: Jessica N
authors.initials: JN
authors.lastname: Mazerik
authors.forename: Valorie
authors.initials: V
authors.lastname: Ciapala
authors.forename: Elizabeth
authors.initials: E
authors.lastname: O'Connor Butler
authors.forename: Jason P
authors.initials: JP
authors.lastname: Cruff
authors.forename: Ulysses
authors.initials: U
authors.lastname: Magalang
authors.forename: Sampath
authors.initials: S
authors.lastname: Parthasarathy
authors.forename: Chandan K
authors.initials: CK
authors.lastname: Sen
authors.forename: Clay B
authors.initials: CB
authors.lastname: Marsh
authors.forename: Periannan
authors.initials: P
authors.lastname: Kuppusamy
authors.forename: Narasimham L
authors.initials: NL
authors.lastname: Parinandi
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism; D001205:Ascorbic Acid / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002384:Catalysis / Q000187:drug effects; D002417:Cattle; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000187:drug effects / Q000201:enzymology*; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007502:Iron Chelating Agents / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects*; D008084:Lipoxygenase / Q000378:metabolism*; D010084:Oxidation-Reduction / Q000187:drug effects; D010739:Phospholipase D / Q000378:metabolism*; D054467:Phospholipases A2 / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D007502:Iron Chelating Agents; D016718:Arachidonic Acid; D008084:Lipoxygenase; D011451:Prostaglandin-Endoperoxide Synthases; D054467:Phospholipases A2; D010739:Phospholipase D; D001205:Ascorbic Acid; D002118:Calcium