The insert region of the Rac GTPases is dispensable for activation of superoxide-producing NADPH oxidases
The insert region of the Rac GTPases is dispensable for activation of superoxide-producing NADPH oxidases
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DOI：
10.1042/bj20082182
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发表时间：
2009-09-01
影响因子：
4.1
通讯作者：
Sumimoto, Hideki
中科院分区：
文献类型：
--
作者：
Miyano, Kei;Koga, Hirofumi;Sumimoto, Hideki
Rac 1和Rac 2属于Ras相关GTP酶的Rho亚家族，在gp 91（phox）/Nox 2（细胞色素B-245，β多肽;也称为Cybb）的活化中发挥重要作用，gp 91/Nox 2是吞噬细胞中产生超氧化物的NADPH氧化酶的催化核心。Rac 1还有助于激活非吞噬性氧化酶Nox 1（NADPH氧化酶1）和Nox 3（NADPH氧化酶3），每一种都与gp 91（phox）/Nox 2密切相关。Rac的插入区域（氨基酸123-135）是Rho亚家族蛋白所特有的，其是否参与gp 91（phox）/Nox 2激活仍然存在争议。在本研究中，我们表明，从Rac I的插入区域的去除既不影响gp 91（phox）/Nox 2，这是在无细胞和全细胞条件下重建的激活，也不阻止其本地化的吞噬体C，在吞噬IgG包被的珠粒由巨噬细胞样RAW264.7细胞摄取。Rac 2的插入区域也在细胞水平上对gp 91（phox）/Nox 2活化起作用。虽然Rac 2和Rac I能够通过Nox 1和Nox 3增强超氧化物的产生，但是这两种GTP酶的增强都与插入区域无关。我们还证明，Rac 3，在哺乳动物中的Rac家族的第三个成员，具有激活三种氧化酶的能力，并且激活不需要插入区域。因此，Rac GTP酶的插入区域不参与Nox家族NADPH氧化酶的调节。
Rac1 and Rac2, which belong to the Rho subfamily of Ras-related GTPascs, play an essential role in activation of gp91(phox)/Nox2 (cytochrome b-245, beta polypeptide; also known as Cybb), the catalytic core of the superoxide-producing NADPH oxidase in phagocytes. Rac1 also contributes to activation of the non-phagocytic oxidases, Nox1 (NADPH oxidase 1) and Nox3 (NADPH oxidase 3), each related closely to gp91(phox)/Nox2. It has remained controversial whether the insert region of Rac (amino acids 123-135), unique to the Rho subfamily proteins, is involved in gp91(phox)/Nox2 activation. In the present study we show that removal of the insert region from Rac I neither affects activation of gp91(phox)/Nox2, which is reconstituted under cell-free and whole-cell conditions, nor blocks its localization to phagosomes C, during ingestion of IgG-coated beads by macrophage-like RAW264.7 cells. The insert region of Rac2 is also dispensable for gp91(phox)/Nox2 activation at the cellular level. Although Rac2, as well as Rac I, is capable of enhancing Superoxide production by Nox1 and Nox3, the enhancements by the two GTPases are both independent of the insert region. We also demonstrate that Rac3, a third member of the Rac family in mammals, has an ability to activate the three oxidases and that the activation does not require the insert region. Thus the insert region of the Rac GTPases does not participate in regulation of the Nox family NADPH oxidases.