Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558
Effects of IFN-γ on intracellular trafficking and activity of macrophage NADPH oxidase flavocytochrome b558
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DOI：
10.1189/jlb.0512244
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发表时间：
2012-10-01
影响因子：
5.5
通讯作者：
Dinauer, Mary C.
中科院分区：
文献类型：
--
作者：
Casbon, Amy-Jo;Long, Matthew E.;Dinauer, Mary C.
黄细胞色素b（558）是吞噬细胞NADPH氧化酶（NOX2）的催化核心，介导NADPH向分子氧的电子转移，产生超氧化物，这是用于宿主防御的高ROS的前体。黄细胞色素b（558）是一种完整的膜异二聚体，由一个大的糖基化亚基gp91（phox）和一个较小的亚基p22（phox）组成。我们最近在小鼠巨噬细胞中发现，黄细胞色素b（558）定位于PM和rab11阳性循环内体，而在原发性hMDMs中，gp91（phox）和p22（phox）存在于PM和内质网。巨噬细胞的抗菌活性，包括ROS的产生，被ifn - γ大大增强，但这是如何实现的还不完全清楚。为了进一步确定ifn - γ增强巨噬细胞NADPH氧化酶活性的机制，我们评估了ifn - γ刺激的RAW 264.7细胞和原代小鼠BMDMs和hMDMs中黄细胞色素b（558）表达和定位以及NADPH氧化酶活性的变化。我们发现，ROS生成能力的增强部分是由于gp91（phox）和p22（phox）蛋白表达的增加，但也表明ifn - γ诱导gp91（phox）和p22（phox）的主要定位从细胞膜内区室转移到PM。我们的研究结果首次表明，细胞因子可以改变巨噬细胞黄细胞色素b（558）的分布，并提供了ifn - γ调节巨噬细胞抗菌活性的潜在新机制。总之，我们的数据表明，ifn - γ调节巨噬细胞抗菌活性的机制比以前所认识的更为复杂。j . Leukoc。生物学杂志。92:869-882；2012.
Flavocytochrome b(558), the catalytic core of the phagocyte NADPH oxidase (NOX2), mediates electron transfer from NADPH to molecular oxygen to generate superoxide, the precursor of highly ROS for host defense. Flavocytochrome b(558) is an integral membrane heterodimer consisting of a large glycosylated subunit, gp91(phox), and a smaller subunit, p22(phox). We recently showed in murine macrophages that flavocytochrome b(558) localizes to the PM and Rab11-positive recycling endosomes, whereas in primary hMDMs, gp91(phox) and p22(phox) reside in the PM and the ER. The antimicrobial activity of macrophages, including ROS production, is greatly enhanced by IFN-gamma, but how this is achieved is incompletely understood. To further define the mechanisms by which IFN-gamma enhances macrophage NADPH oxidase activity, we evaluated changes in flavocytochrome b(558) expression and localization, along with NADPH oxidase activity, in IFN-gamma stimulated RAW 264.7 cells and primary murine BMDMs and hMDMs. We found that enhanced capacity for ROS production is, in part, a result of increased protein expression of gp91(phox) and p22(phox) but also demonstrate that IFN-gamma induced a shift in the predominant localization of gp91(phox) and p22(phox) from intracellular membrane compartments to the PM. Our results are the first to show that a cytokine can change the distribution of macrophage flavocytochrome b(558) and provide a potential, new mechanism by which IFN-gamma modulates macrophage antimicrobial activity. Altogether, our data suggest that the mechanisms by which IFN-gamma regulates antimicrobial activity of macrophages are more complex than previously appreciated. J. Leukoc. Biol. 92: 869-882; 2012.