title: Activation of endothelial cell phospholipase D by polycations.
abstract: Naturally occurring polycations and cationic proteins are implicated in vascular disorders. It is known that activated leukocytes and platelets release polycations, such as polylysine (PLys), of varying molecular sizes into the vasculature, and some of these have been described to be bactericidal. Polycations interact with endothelial cells (ECs) and cause alterations in permeability and cellular functions. The precise mechanism(s) by which polycations bring about cellular changes is unknown. Here, we report that the polycations PLys and polyarginine (PArg) induce phospholipase D (PLD) activation in ECs. Polycation-mediated PLD activation was both time and concentration dependent, and activation of PLD was not due to cytotoxicity. PArg was more potent compared with PLys of the same molecular weight in stimulation of PLD. Treatment with bisindolylmaleimide, a specific protein kinase C (PKC) inhibitor, and heparin attenuated polycation-mediated PLD activation. Furthermore, downregulation of PKC by 12-O-tetradecanoylphorbol-13-acetate (100 nM, 18 h) also blocked polycation-mediated PLD stimulation. These data suggest that polycation-mediated PLD stimulation probably involves PKC and may represent an important cellular response to leukocyte/platelet activation in the vascular endothelium.
authors.affiliation: Department of Medicine, Indiana University School of Medicine, Indianapolis 46202-2879, USA.
authors.forename: S
authors.initials: S
authors.lastname: Vepa
authors.forename: W M
authors.initials: WM
authors.lastname: Scribner
authors.forename: V
authors.initials: V
authors.lastname: Natarajan
mesh_terms: D016475:3T3 Cells / Q000201:enzymology; D000818:Animals; D002412:Cations / Q000494:pharmacology*; D002417:Cattle; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000201:enzymology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology; D010455:Peptides / Q000494:pharmacology; D011107:Polylysine / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011651:Pulmonary Artery / Q000166:cytology / Q000201:enzymology
chemical_list: D002412:Cations; D004791:Enzyme Inhibitors; D010455:Peptides; D047428:Protein Kinase Inhibitors; D011107:Polylysine; C015462:polyarginine; D007770:L-Lactate Dehydrogenase