Impaired NADPH oxidase activity in Rac2-deficient murine neutrophils does not result from defective translocation of p47phox and p67phox and can be rescued by exogenous arachidonic acid
Impaired NADPH oxidase activity in Rac2-deficient murine neutrophils does not result from defective translocation of p47phox and p67phox and can be rescued by exogenous arachidonic acid
复制标题
DOI：
10.1189/jlb.0705371
复制
发表时间：
2006-01-01
影响因子：
5.5
通讯作者：
Dinauer, MC
中科院分区：
文献类型：
--
作者：
Kim, C;Dinauer, MC
Rac2 是一种造血特异性 Rho-GTP 酶，在调节中性粒细胞中还原型烟酰胺腺嘌呤二核苷酸磷酸 (NADPH) 氧化酶激活和其他功能反应中发挥刺激特异性作用。在这项研究中，rac2-/-中性粒细胞响应外源花生四烯酸（AA）而显着降低 NADPH 氧化酶活性和肌动蛋白重塑，正如之前观察到的佛波醇 12-肉豆蔻酸酯 13-乙酸酯（PMA）或甲酰基-Met-Leu-Phe（fMLP）作为激动剂。 PMA、fMLP 或 AA 诱导的 p47(phox) 和 p67(phox) 向质膜的易位在 rac2-/- 中性粒细胞中并未受损。外源 AA 和 PMA 联合刺激 rac2-/- 中性粒细胞对 NADPH 氧化酶活性具有协同作用，超氧化物产量增加到至少与野生型细胞一样高的水平，并且对 fMLP 引发的酶活性没有影响。 PMA 和 AA 联合刺激不会进一步增加 p47(phox) 和 p67(phox) 的膜易位以及 Rac1 激活。抑制剂研究与佛波酯激活蛋白激酶 C (PKC) 异构体和非典型异构体 PKC zeta 在 AA 和 PMA 刺激的野生型和 rac2-/- 中性粒细胞产生超氧化物中的重要作用一致。此外，PMA 刺激的 rac2-/- 中性粒细胞中 AA 的释放和细胞质磷脂酶 A(2) 的表达与野生型相似，表明 PMA 刺激的 rac2-/- 中性粒细胞产生的 AA 不足并不能解释外源 AA 对氧化酶活性的影响。虽然 p47(phox) 和 p67(phox) 的易位不需要 Rac2，但 Rac2 对于组装的氧化酶复合物的最佳活性是必需的，这种作用可以被外源 AA 取代，外源 AA 可以直接作用或通过外源 AA 诱导的介质发挥作用。
Rac2 is a hematopoietic-specific Rho-GTPase that plays a stimulus-specific role in regulating reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activation and other functional responses in neutrophils. In this study, rac2-/- neutrophils were shown to have significantly-decreased NADPH oxidase activity and actin remodeling in response to exogenous arachidoinic acid (AA), as previously observed for phorbol 12-myristate 13-acetate (PMA) or formyl-Met-Leu-Phe (fMLP) as agonists. PMA-, fMLP-, or AA-induced translocation of p47(phox) and p67(phox) to the Plasma membrane was not impaired in rac2-/- neutrophils. Combined stimulation of rac2-/- neutrophils with exogenous AA and PMA had a synergistic effect on NADPH oxidase activity, and superoxide production increased to a level that was at least as high as wild-type cells and had no effect on fMLP-elicited enzyme activity. Membrane translocation of p47(phox) and p67(phox) as well as Rac1 activation was not increased further by combined PMA and AA stimulation. Inhibitor studies were consistent with important roles for phorbol ester-activated protein kinase C (PKC) isoforms and an atypical isoform, PKC zeta, in superoxide production by wildtype and rac2-/- neutrophils stimulated with AA and PMA. In addition, PMA-stimulated release of AA and cytoplasmic phospholipase A(2) expression in rac2-/- neutrophils were similar to wild-type, suggesting that deficient AA production by PMA-stimulated rac2-/- neutrophils does not explain the effect of exogenous AA on oxidase activity. Although not required for translocation of p47(phox) and p67(phox), Rac2 is necessary for optimal activity of the assembled oxidase complex, an effect that can be replaced by exogenous AA, which may act directly or via an exogenous AA-induced mediator.