Cancer Research Center, Xiamen University Medical College, Xiamen, China.
J Cell Mol Med. 2011 Mar;15(3):647-53. doi: 10.1111/j.1582-4934.2010.01035.x.
The phorbol myristate acetate (PMA) stimulated nutrophil respiratory burst has been considered to simply involve the activation of protein kinase C (PKC). However, the PLD activity was also increased by 10-fold in human neutrophils stimulated with 100 nM PMA. Unexpectedly, U73122, an inhibitor of phospholipase C, was found to significantly inhibit PMA-stimulated respiratory burst in human neutrophils. U73122 at the concentrations, which were sufficient to inhibit the respiratory burst completely, caused partial inhibition of the PLD activity but no inhibition on PKC translocation and activation, suggesting that PLD activity is also required in PMA-stimulated respiratory burst. Using 1-butanol, a PLD substrate, to block phosphatidic acid (PA) generation, the PMA-stimulated neutrophil respiratory burst was also partially inhibited, further indicating that PLD activation, possibly its hydrolytic product PA and diacylglycerol (DAG), is involved in PMA-stimulated respiratory burst. Since GF109203X, an inhibitor of PKC that could completely inhibit the respiratory burst in PMA-stimulated neutrophils, also caused certain suppression of PLD activation, it may suggest that PLD activation in PMA-stimulated neutrophils might be, to some extent, PKC dependent. To further study whether PLD contributes to the PMA stimulated respiratory burst through itself or its hydrolytic product, 1,2-dioctanoyl-sn-glycerol, an analogue of DAG , was used to prime cells at low concentration, and it reversed the inhibition of PMA-stimulated respiratory burst by U73122. The results indicate that U73122 may act as an inhibitor of PLD, and PLD activation is required in PMA-stimulated respiratory burst.
佛波醇肉豆蔻酸酯（PMA）刺激中性粒细胞呼吸爆发被认为仅仅涉及蛋白激酶 C（PKC）的激活。然而，在 100 nM PMA 刺激的人中性粒细胞中，PLD 活性也增加了 10 倍。出乎意料的是，发现磷脂酶 C 的抑制剂 U73122 可显著抑制人中性粒细胞中 PMA 刺激的呼吸爆发。在足以完全抑制呼吸爆发的浓度下，U73122 引起 PLD 活性的部分抑制，但对 PKC 易位和激活没有抑制作用，表明 PLD 活性也需要在 PMA 刺激的呼吸爆发中。使用 1-丁醇作为 PLD 底物来阻断磷脂酸（PA）的产生，PMA 刺激的中性粒细胞呼吸爆发也被部分抑制，进一步表明 PLD 激活，可能是其水解产物 PA 和二酰基甘油（DAG），参与 PMA 刺激的呼吸爆发。由于 GF109203X，一种可以完全抑制 PMA 刺激的中性粒细胞呼吸爆发的 PKC 抑制剂，也对 PLD 激活产生一定的抑制作用，这可能表明在 PMA 刺激的中性粒细胞中，PLD 激活在某种程度上依赖于 PKC。为了进一步研究 PLD 是否通过自身或其水解产物 DAG 的类似物 1,2-二油酰基-sn-甘油来促进 PMA 刺激的呼吸爆发，用低浓度的 1,2-二油酰基-sn-甘油预先处理细胞，逆转了 U73122 对 PMA 刺激的呼吸爆发的抑制作用。结果表明，U73122 可能作为 PLD 的抑制剂起作用，并且 PLD 激活是 PMA 刺激的呼吸爆发所必需的。
