Laboratory of Molecular Cell Biology, Centre for DNA Fingerprinting and Diagnostics, Hyderabad, Telangana 500039, India.
Graduate Studies, Manipal Academy of Higher Education, Manipal, Karnataka 576104, India; and.
J Immunol. 2019 Sep 1;203(5):1218-1229. doi: 10.4049/jimmunol.1801143. Epub 2019 Aug 2.
employs defense mechanisms to protect itself from reactive oxygen species (ROS)-mediated cytotoxicity inside macrophages. In the current study, we found that a secretory protein of PPE2 disrupted the assembly of NADPH oxidase complex. PPE2 inhibited NADPH oxidase-mediated ROS generation in RAW 264.7 macrophages and peritoneal macrophages from BALB/c mice. PPE2 interacted with the cytosolic subunit of NADPH oxidase, p67, and prevented translocation of p67 and p47 to the membrane, resulting in decreased NADPH oxidase activity. Trp236 residue present in the SH3-like domain of PPE2 was found to be critical for its interaction with p67 Trp236Ala mutant of PPE2 did not interact with p67 and thereby did not affect ROS generation. expressing PPE2 and PPE2-null mutants complemented with PPE2 survived better than PPE2-null mutants in infected RAW 264.7 macrophages. Altogether, this study suggests that PPE2 inhibits NADPH oxidase-mediated ROS production to favor survival in macrophages. The findings that PPE2 protein is involved in the modulation of oxidative response in macrophages will help us in improving our knowledge of host-pathogen interactions and the application of better therapeutics against tuberculosis.
利用防御机制来保护自身免受巨噬细胞内活性氧物种 (ROS) 介导的细胞毒性。在本研究中，我们发现 PPE2 的一种分泌蛋白破坏了 NADPH 氧化酶复合物的组装。PPE2 抑制 RAW 264.7 巨噬细胞和 BALB/c 小鼠腹腔巨噬细胞中的 NADPH 氧化酶介导的 ROS 生成。PPE2 与 NADPH 氧化酶的胞质亚基 p67 相互作用，并阻止 p67 和 p47 向膜的易位，从而降低 NADPH 氧化酶活性。存在于 PPE2 的 SH3 样结构域中的 Trp236 残基对于其与 p67 的相互作用至关重要，而 PPE2 的 Trp236Ala 突变体与 p67 不相互作用，因此不会影响 ROS 的产生。表达 PPE2 和用 PPE2 互补的 PPE2 缺失突变体在感染的 RAW 264.7 巨噬细胞中比 PPE2 缺失突变体存活得更好。总的来说，这项研究表明 PPE2 抑制 NADPH 氧化酶介导的 ROS 产生，有利于在巨噬细胞中的存活。发现 PPE2 蛋白参与调节巨噬细胞中的氧化反应，将有助于我们提高对宿主-病原体相互作用的认识，并应用更好的结核病治疗方法。
