Experimental studies on the mechanism of phospholipase C activation by the lipid peroxidation products 4-hydroxynonenal and 2-nonenal.
The effects of three lipid peroxidation end-products, 4-hydroxynonenal (HNE), 2-nonenal (NE) and nonanal, on phosphoinositide-specific phospholipase C (PL-C) activity were studied in HL-60 cells. Enzymatic activity was determined by measuring the amounts of inositol-P3 (Ins-P3) produced by the cells incubated at 37 degrees C in the presence of the various compounds. HNE was shown to activate PL-C at concentrations of between 10(-8) and 10(-6) M; 10(-9) and 10(-8) M of NE also strongly stimulated PL-C. In contrast, nonanal failed to modify enzymatic activity. The concentrations of HNE and NE active on PL-C showed good correspondence with those that have been reported to be chemotactic towards rat neutrophils. The pretreatment of cells with 1 microM pertussis toxin completely prevented the increase of Ins-P3 production induced by HNE and NE. Maximal PL-C stimulation was produced by 10 nM NE; the degree of inositol-P3 production induced by the simultaneous addition of an equimolar dose of HNE was not significantly different from the activity value induced by NE alone, suggesting a possible competition between the two compounds. The data indicate that both HNE and NE share a common mechanism of action which, as with other better-known chemoattractants, involves PL-C activation through a G regulatory protein.
Rossi
M A
MA
Department of Experimental Medicine and Oncology, General Pathology Section, University of Turin, Turin, Italy.
Di Mauro
C
C
Dianzani
M U
MU
D000447:Aldehydes / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007700:Kinetics; D015227:Lipid Peroxidation / Q000502:physiology; D037342:Pertussis Toxin; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000096:biosynthesis* / Q000187:drug effects; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000447:Aldehydes; D015853:Cysteine Proteinase Inhibitors; D010566:Virulence Factors, Bordetella; C013166:2-nonenal; C008664:nonanal; D015544:Inositol 1,4,5-Trisphosphate; D037342:Pertussis Toxin; D010738:Type C Phospholipases; C027576:4-hydroxy-2-nonenal