Experimental researches on the role of phosphoinositide-specific phospholipase C in 4-hydroxynonenal induced exocytosis.
The action of 4-hydroxynonenal (HNE), a chemotactic aldehyde produced by lipid peroxidation, was analysed on exocytosis in parallel with its effects on phosphoinositide-specific phospholipase C (PLC) both in undifferentiated HL-60 cells and in cells induced to differentiate toward the granulocytic cell line by 1.25% DMSO. Exocytosis was evaluated by the secretion of beta-glucuronidase from cells incubated at 37 degrees C for 10 min in the presence of various aldehyde concentrations. HNE action was more pronounced in DMSO-differentiated cells, where concentrations between 10(-8) and 10(-6) m were able both to trigger exocytosis and to strongly activate PLC; in both processes maximal stimulation was given by 10(-7) m. HNE-induced exocytosis was completely prevented by pertussis toxin and by the PLC inhibitor U73122. The comparison between HNE and formyl-methionyl-leucyl-phenylalanine (fMLP), used as a positive control, showed that the tripeptide produced an higher stimulation of exocytosis than the aldehyde; by contrast HNE induced a stronger increase of PLC activity. Wortmannin, an inhibitor of phosphatidylinositol-3-kinase (PI3K), strongly inhibited the exocytosis induced by fMLP, while it failed to induce a statistically significant inhibition of HNE action. We conclude that both compounds trigger exocytosis through a Ptx-sensitive G protein; the present data support the hypothesis that the lower ability of the aldehyde to trigger exocytosis as compared to fMLP might depend upon a low ability to activate PI3K, while PLC activation appears to play a key role in HNE-induced exocytosis.
Department of Experimental Medicine and Oncology, University of Turin, Corso Raffaello 30, 10125 Torino, Italy.
Marina
M
Maggiora
Maria
M
Armida Rossi
D000447:Aldehydes / Q000494:pharmacology*; D000730:Androstadienes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005089:Exocytosis / Q000187:drug effects / Q000502:physiology*; D005966:Glucuronidase / Q000187:drug effects*; D006801:Humans; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D000077191:Wortmannin
D000447:Aldehydes; D000730:Androstadienes; D010726:Phosphodiesterase Inhibitors; D009240:N-Formylmethionine Leucyl-Phenylalanine; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D005966:Glucuronidase; C027576:4-hydroxy-2-nonenal; D000077191:Wortmannin