EBP50 induces apoptosis in macrophages by upregulating nitric oxide production to eliminate intracellular Mycobacterium tuberculosis.
EBP50 induces apoptosis in macrophages by upregulating nitric oxide production to eliminate intracellular Mycobacterium tuberculosis.
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DOI：
10.1038/srep18961
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发表时间：
2016-01-05
影响因子：
4.6
通讯作者：
Li J
中科院分区：
文献类型：
--
作者：
Guo Y;Deng Y;Huang Z;Luo Q;Peng Y;Chen J;Jiang H;Ye J;Li J
已知牛分枝杆菌BCG能够通过干扰EBP50抑制iNOS在含BCG的吞噬体上的定位，EBP50是一种控制巨噬细胞吞噬体附近诱导型一氧化氮合酶（iNOS）募集的支架蛋白。然而，敲低EBP50的表达仍然有利于卡介苗的细胞内存活，这表明EBP50可能具有一些其他未知的抗细菌特性。在本研究中，我们发现重组慢病毒过表达EBP50对含有结核分枝杆菌的吞噬体募集iNOS没有影响，但能显著促进细胞内结核分枝杆菌的清除。我们在本研究中发现，EBP50过表达后细胞内对结核分枝杆菌的杀伤能力增强是由于巨噬细胞凋亡水平的增加。我们发现EBP50过表达显著增加了iNOS的表达和一氧化氮（NO）的产生，并且EBP50诱导的细胞凋亡是NO依赖性的，由Bax和caspase-3介导。在RAW264.7细胞中，我们发现结核分枝杆菌降低EBP50的表达，而垢垢分枝杆菌增加EBP50的表达，这表明毒力强的分枝杆菌能够通过抑制EBP50的表达和干扰其功能来调节巨噬细胞的抗细菌特性。
Mycobacterium bovis BCG is known to have the capacity to inhibit the positioning of iNOS on BCG-containing phagosomes by interfering with EBP50, a scaffolding protein that controls the recruitment of inducible nitric oxide synthase (iNOS) at the vicinity of phagosomes in macrophages. However, knockdown of the expression of EBP50 still facilitates the intracellular survival of BCG, which suggested that EBP50 may have some other unknown antimycobacterial properties. In this study we show that overexpression of EBP50 by a recombinant lentivirus had no effect on the iNOS recruitment to M.tuberculosis-containing phagosomes, but significantly promoted the elimination of intracellular M.tuberculosis. We revealed in the present study that the enhancement of intracellular killing to M. tuberculosis upon EBP50 overexpression was due to the increased level of apoptosis in macrophages. We showed that EBP50 overexpression significantly increased the expression of iNOS and generation of nitric oxide (NO), and EBP50-induced apoptosis was NO-dependent and mediated by Bax and caspase-3. We found that M. tuberculosis decreases while Mycobacterium smegmatis increases the expression of EBP50 in RAW264.7 cells, which suggested that virulent mycobacteria are capable of modulating the antimycobacterial properties of macrophages by inhibiting the expression and interfering with the function of EBP50.