Phosphoinositide 3-kinase regulates the phosphorylation of NADPH oxidase component p47(phox) by controlling cPKC/PKCdelta but not Akt.
Phosphoinositide 3-kinase regulates the phosphorylation of NADPH oxidase component p47(phox) by controlling cPKC/PKCdelta but not Akt.
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DOI：
10.1016/j.bbrc.2004.02.108
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发表时间：
2004-04
影响因子：
3.1
通讯作者：
T. Yamamori;O. Inanami;H. Nagahata;M. Kuwabara
中科院分区：
文献类型：
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作者：
T. Yamamori;O. Inanami;H. Nagahata;M. Kuwabara
NADPH氧化酶产生的超氧化物对吞噬细胞的杀菌性能至关重要。p47phox是NADPH氧化酶的胞质组分之一，其磷酸化是氧化酶激活的关键步骤。有证据表明，PI3K参与了p47磷酸化过程，但其调控机制尚不完全清楚。本研究的目的是研究PI3K调控p47磷酸化的机制。在HL-60细胞分化为中性粒细胞样表型时，PI3K的药理抑制可减弱fmlp刺激的p47磷酸化和NADPH氧化酶活性。虽然fMLP以pi3k依赖的方式激活Akt，但Akt抑制剂对fMLP触发的氧化酶活性没有影响。体外激酶实验显示Akt不能催化p47磷酸化。有趣的是，fMLP刺激后cPKC和PKCδ的激活依赖于PI3K。此外，PI3K抑制剂在不影响酪氨酸磷酸化的情况下降低了磷脂酶c - γ - 2的活化。这些结果表明，PI3K通过控制二酰基甘油依赖性PKCs而不是Akt来调节NADPH氧化酶组分p47phoxp的磷酸化。
Superoxide production by NADPH oxidase is essential for the bactericidal properties of phagocytes. Phosphorylation of p47phox, one of the cytosolic components of NADPH oxidase, is a crucial step of the oxidase activation. Some evidences suggest that phosphoinositide 3-kinase (PI3K) is involved in p47phoxphosphorylation, but it has not been fully understood how PI3K regulates it. The aim of this study was to examine the mechanism underlying the PI3K regulation of p47phoxphosphorylation. Pharmacological inhibition of PI3K attenuated both fMLP-stimulated p47phoxphosphorylation and NADPH oxidase activity in HL-60 cells differentiated to a neutrophil-like phenotype. Although fMLP elicited Akt activation in a PI3K-dependent manner, an Akt inhibitor had no effect on the oxidase activity triggered by fMLP. In vitro kinase assay revealed that Akt was unable to catalyze p47phoxphosphorylation. Interestingly, the activation of cPKC and PKCδ after fMLP stimulation was dependent on PI3K. Furthermore, PI3K inhibitors reduced the activation of phospholipase Cγ2 without affecting tyrosine phosphorylation on it. These results suggest that PI3K regulates the phosphorylation of NADPH oxidase component p47phoxby controlling diacylglycerol-dependent PKCs but not Akt.