Inhibition by HAJ11 of respiratory burst in neutrophils and the involvement of protein tyrosine phosphorylation and phospholipase D activation.
1. The possible mechanisms of the inhibitory effect of ethyl 2-(3-hydroxyanilino)-4-oxo-4,5-dihydrofuran-3-carboxylate (HAJ11) on the respiratory burst of rat neutrophils in vitro was investigated. 2. HAJ11 caused a reversible and a concentration-dependent inhibition of formyl-Met-Leu-Phe (fMLP)-induced superoxide anion (O2.-) generation (IC50 4.9 +/- 0.7 microM) and O2 consumption (IC50 4.9 +/- 1.5 microM). Concanavalin A (Con A)- and NaF-induced O2.- generation were also suppressed by HAJ11. However, HAL11 was a weak inhibitor of the phorbol 12-myristate 13-acetate (PMA)-induced responses. 3. HAJ11 did not scavenge the /2.- generation in the xanthine-xanthine oxidase system and dihydroxyfumaric acid (DHF) autoxidation. 4. HAJ11 showed no activity on fMLP-induced inositol phosphates formation and [Ca2+]i elevation in intact neutrophils. In addition, HAJ11 had no effect on neutrophil cytosolic phospholipase C (PLC) activity. 5. HAJ11 reduced fMLP-induced phosphatidic acid (PA) (IC50 29.1 +/- 6.5 microM) and phosphatidylethanol (PE+) (IC50 22.6 +/- 1.9 microM) formation in a concentration-dependent manner. HAJ11 also reduced protein tyrosine phosphorylation in neutrophils stimulated by fMLP. 6. HAJ11 was a weak inhibitor of neutrophil cytosolic protein kinase C (PKC) activity, and had a negligible effect on brain PKC. Cellular cyclic nucleotides levels were not altered by HAJ11. In addition, HAJ11 did not affect protein kinase A (PKA) activity. 7. HAJ11 had not effect on the O2.- generation of PMA-activated and arachidonic acid (AA)-activated NADPH oxidase preparations. 8. Taken together these results indicate that the inhibition of respiratory burst by HAJ11 probably mainly occurs through inhibition of protein tyrosine phosphorylation and phospholipase D (PLD) activity.
Wang
J P
JP
Department of Medical Research, Taichung Veterans General Hospital, Taiwan, Republic of China.
Tsao
L T
LT
Raung
S L
SL
Hsu
M F
MF
Kuo
S C
SC
D000818:Animals; D002118:Calcium / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005663:Furans / Q000494:pharmacology*; D066298:In Vitro Techniques; D007293:Inosine Triphosphate / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000201:enzymology; D019255:NADPH Oxidases / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D016897:Respiratory Burst / Q000187:drug effects*; D010738:Type C Phospholipases / Q000378:metabolism
D004791:Enzyme Inhibitors; D005663:Furans; C105213:HAJ11; D007293:Inosine Triphosphate; D000242:Cyclic AMP; D019255:NADPH Oxidases; D017027:Protein Tyrosine Phosphatases; D010738:Type C Phospholipases; D010739:Phospholipase D; D006152:Cyclic GMP; D002118:Calcium