Am. J. Respir. Cell Mol. Biol., Vol 17, No. 2, 08 1997, 251-259.
Phosphatase inhibitors potentiate 4-hydroxynonenal-induced phospholipase D activation in vascular endothelial cells
V Natarajan, WM Scribner and S Vepa
Department of Medicine, Indiana University School of Medicine, Indianapolis 46202, USA.
We have previously reported that endothelial cell phospholipase D (PLD),
activated by 4-hydroxynonenal (4-HNE), was independent of protein kinase C
activation. To determine whether PLD stimulation by 4- HNE is related to
protein tyrosine phosphorylation, the effects of tyrosine kinase (Tyrk) and
protein tyrosine phosphatase (PTPase) inhibitors on PLD activation were
investigated. Pretreatment of bovine pulmonary artery endothelial cells
(BPAEC) with Tyrk inhibitors, such as genistein, erbstatin, and herbimycin
attenuated 4-HNE-induced PLD activation. Furthermore, vanadate,
phenylarsine oxide, and diamide, inhibitors of PTPases, markedly increased
the 4-HNE-induced PLD activation. The effects of Tyrk and PTPase inhibitors
were specific towards the 4-HNE, as these agents had no effect on the
agonist- or TPA- induced PLD activation. In addition to PLD activation,
treatment of BPAEC with 4-HNE increased tyrosine phosphorylation of
proteins including bands of molecular weights 40,000-60,000, 70,000-90,000,
and 110,000-130,000. The 4-HNE-mediated increase in protein tyrosine
phosphorylation was partly inhibited by genistein (100 microM). Vanadate
(10 microM) pretreatment also potentiated 4-HNE-induced protein tyrosine
phosphorylation. These data suggest that 4-HNE- mediated stimulation of PLD
may occur as a result of activation of tyrosine kinases.
