The PGRS Domain of Mycobacterium tuberculosis PE_PGRS Protein Rv0297 Is Involved in Endoplasmic Reticulum Stress-Mediated Apoptosis through Toll-Like Receptor 4.
The PGRS Domain of Mycobacterium tuberculosis PE_PGRS Protein Rv0297 Is Involved in Endoplasmic Reticulum Stress-Mediated Apoptosis through Toll-Like Receptor 4.
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DOI：
10.1128/mbio.01017-18
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发表时间：
2018-06-19
期刊：
影响因子：
6.4
通讯作者：
Hasnain SE
中科院分区：
文献类型：
--
作者：
Grover S;Sharma T;Singh Y;Kohli S;P M;Singh A;Semmler T;Wieler LH;Tedin K;Ehtesham NZ;Hasnain SE
结核分枝杆菌（Mycobacterium tuberculosis，TB）的基因组编码称为PE/PPE/PGRS家族的独特蛋白质家族，该蛋白质家族仅存在于分枝杆菌属中，在生物界中没有其他地方，具有很大程度上未探索的功能。我们描述的PGRS域的Rv 0297，这个家庭的成员的功能意义。计算机模拟分析揭示了Rv 0297（Rv 0297 PGRS）的PGRS结构域中存在内在无序的延伸和推定的内质网（ER）定位信号。PGRS结构域有助于ER定位，这通过用M.结核病和通过在巨噬细胞中转染过表达蛋白，随后激活未折叠蛋白应答，如从GRP 78/GRP 94和CHOP/ATF 4的表达增加所证明的，导致细胞内Ca 2+稳态的破坏和一氧化氮（NO）和活性氧（ROS）产生增加。随后激活效应caspase-8导致巨噬细胞凋亡，这是Toll样受体4（TLR 4）依赖性的。施用重组Rv 0297 PGRS（rRv 0297 PGRS）也表现出类似的效果。这些结果暗示了PE_PGRS蛋白家族的PGRS结构域在ER应激介导的细胞死亡中通过TLR 4的迄今未知的作用。由于已知这种蛋白质存在于人类肉芽肿感染的后期阶段，它指出了它被M.结核病通过凋亡机制传播。细胞凋亡通常被认为是在感染的早期阶段保护宿主抵抗结核分枝杆菌的防御机制。然而，在肺肉芽肿的后期阶段，细胞凋亡可能有利于细菌传播疾病。已经发现ER应激诱导TB肉芽肿中的细胞凋亡，在小鼠和人类中细胞凋亡的巨噬细胞聚集的区域中。在这项研究中，我们报告了ER应激介导的宿主细胞凋亡的Rv 0297编码的PE_PGRS5蛋白的M。结核病特别存在于致病性分枝杆菌属中。Rv 0297的PGRS结构域有助于蛋白定位于ER，并诱导未折叠的蛋白反应，随后是巨噬细胞的凋亡。发现Rv 0297 PGRS结构域的作用是TLR 4依赖性的。本研究对M.结核病传播疾病。
The genome of Mycobacterium tuberculosis, the causal organism of tuberculosis (TB), encodes a unique protein family known as the PE/PPE/PGRS family, present exclusively in the genus Mycobacterium and nowhere else in the living kingdom, with largely unexplored functions. We describe the functional significance of the PGRS domain of Rv0297, a member of this family. In silico analyses revealed the presence of intrinsically disordered stretches and putative endoplasmic reticulum (ER) localization signals in the PGRS domain of Rv0297 (Rv0297PGRS). The PGRS domain aids in ER localization, which was shown by infecting macrophage cells with M. tuberculosis and by overexpressing the protein by transfection in macrophage cells followed by activation of the unfolded protein response, as evident from increased expression of GRP78/GRP94 and CHOP/ATF4, leading to disruption of intracellular Ca2+ homeostasis and increased nitric oxide (NO) and reactive oxygen species (ROS) production. The consequent activation of the effector caspase-8 resulted in apoptosis of macrophages, which was Toll-like receptor 4 (TLR4) dependent. Administration of recombinant Rv0297PGRS (rRv0297PGRS) also exhibited similar effects. These results implicate a hitherto-unknown role of the PGRS domain of the PE_PGRS protein family in ER stress-mediated cell death through TLR4. Since this protein is already known to be present at later stages of infection in human granulomas it points to the possibility of it being employed by M. tuberculosis for its dissemination via an apoptotic mechanism. Apoptosis is generally thought to be a defense mechanism in protecting the host against Mycobacterium tuberculosis in early stages of infection. However, apoptosis during later stages in lung granulomas may favor the bacterium in disseminating the disease. ER stress has been found to induce apoptosis in TB granulomas, in zones where apoptotic macrophages accumulate in mice and humans. In this study, we report ER stress-mediated apoptosis of host cells by the Rv0297-encoded PE_PGRS5 protein of M. tuberculosis exceptionally present in the pathogenic Mycobacterium genus. The PGRS domain of Rv0297 aids the protein in localizing to the ER and induces the unfolded protein response followed by apoptosis of macrophages. The effect of the Rv0297PGRS domain was found to be TLR4 dependent. This study presents novel insights on the strategies employed by M. tuberculosis to disseminate the disease.