Brucella Rough Mutant Induce Macrophage Death via Activating IRE1α Pathway of Endoplasmic Reticulum Stress by Enhanced T4SS Secretion.
Brucella Rough Mutant Induce Macrophage Death via Activating IRE1α Pathway of Endoplasmic Reticulum Stress by Enhanced T4SS Secretion.
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布鲁氏菌粗糙突变体通过增强T4SS分泌激活内质网应激的IRE1α途径诱导巨噬细胞死亡
DOI：
10.3389/fcimb.2017.00422
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发表时间：
2017
影响因子：
5.7
通讯作者：
Yu S
中科院分区：
文献类型：
--
作者：
Li P;Tian M;Bao Y;Hu H;Liu J;Yin Y;Ding C;Wang S;Yu S
布鲁氏菌是一种革兰氏阴性兼性胞内病原体，可引发世界范围内的人畜共患病——布鲁氏菌病。布鲁氏菌的毒力主要依赖于其侵入吞噬细胞并在其中复制的能力。Ⅳ型分泌系统（T4SS）和脂多糖是布鲁氏菌的两个主要毒力因子。据报道，布鲁氏菌粗糙型突变株可诱导被感染的巨噬细胞死亡，这依赖于T4SS。然而，潜在的分子机制仍不清楚。在本研究中，通过构建融合萤火虫荧光素酶的T4SS效应蛋白BPE123和VceC，对布鲁氏菌粗糙型突变株及其光滑野生型菌株的T4SS分泌能力进行了比较研究。此外，还使用实时定量PCR和蛋白质印迹法分析了T4SS的表达。结果表明，布鲁氏菌粗糙型突变株中T4SS的表达和分泌显著增强。我们还发现，布鲁氏菌粗糙型突变株中T4SS virB操纵子启动子的活性显著增加，这依赖于群体感应相关调节因子VjbR的上调。细胞感染和细胞死亡实验表明，在布鲁氏菌粗糙型突变株中缺失vjbR可通过下调T4SS表达完全消除巨噬细胞内的细胞毒性。这表明在粗糙型突变株ΔrfbE中，VjbR促进的T4SS上调有助于巨噬细胞死亡。此外，我们发现布鲁氏菌粗糙型突变株通过激活内质网应激的IRE1α通路诱导巨噬细胞死亡。综上所述，我们的研究提供的证据表明，与布鲁氏菌光滑野生型菌株相比，布鲁氏菌粗糙型突变株中VjbR的上调增加了virB操纵子的转录，导致T4SS基因过度表达，同时效应蛋白过度分泌，从而通过激活内质网应激的IRE1α通路导致被感染的巨噬细胞死亡，这为布鲁氏菌粗糙型突变株诱导巨噬细胞细胞毒性相关的分子机制提供了新的见解。
Brucella is a Gram-negative facultative intracellular pathogen that causes the worldwide zoonosis, known as brucellosis. Brucella virulence relies mostly on its ability to invade and replicate within phagocytic cells. The type IV secretion system (T4SS) and lipopolysaccharide are two major Brucella virulence factors. Brucella rough mutants reportedly induce the death of infected macrophages, which is T4SS dependent. However, the underlying molecular mechanism remains unclear. In this study, the T4SS secretion capacities of Brucella rough mutant and its smooth wild-type strain were comparatively investigated, by constructing the firefly luciferase fused T4SS effector, BPE123 and VceC. In addition, quantitative real-time PCR and western blotting were used to analyze the T4SS expression. The results showed that T4SS expression and secretion were enhanced significantly in the Brucella rough mutant. We also found that the activity of the T4SS virB operon promoter was notably increased in the Brucella rough mutant, which depends on quorum sensing-related regulators of VjbR upregulation. Cell infection and cell death assays revealed that deletion of vjbR in the Brucella rough mutant absolutely abolished cytotoxicity within macrophages by downregulating T4SS expression. This suggests that up-regulation of T4SS promoted by VjbR in rough mutant ΔrfbE contribute to macrophage death. In addition, we found that the Brucella rough mutant induce macrophage death via activating IRE1α pathway of endoplasmic reticulum stress. Taken together, our study provide evidence that in comparison to the Brucella smooth wild-type strain, VjbR upregulation in the Brucella rough mutant increases transcription of the virB operon, resulting in overexpression of the T4SS gene, accompanied by the over-secretion of effecter proteins, thereby causing the death of infected macrophages via activating IRE1α pathway of endoplasmic reticulum stress, suggesting novel insights into the molecular mechanisms associated with Brucella rough mutant-induced macrophage cytotoxicity.
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影响因子：
32.4
作者：
Bronner DN;Abuaita BH;Chen X;Fitzgerald KA;Nuñez G;He Y;Yin XM;O'Riordan MX
通讯作者：
O'Riordan MX
影响因子：
3.2
作者：
FREEMAN, BA;RUMACK, BH
通讯作者：
RUMACK, BH
影响因子：
3.1
作者：
He, Yongqun;Reichow, Sherry;Boyle, Stephen M.
通讯作者：
Boyle, Stephen M.
影响因子：
3.1
作者：
Kahl-McDonagh, M. M.;Ficht, T. A.
通讯作者：
Ficht, T. A.
影响因子：
64.8
作者：
Keestra-Gounder AM;Byndloss MX;Seyffert N;Young BM;Chávez-Arroyo A;Tsai AY;Cevallos SA;Winter MG;Pham OH;Tiffany CR;de Jong MF;Kerrinnes T;Ravindran R;Luciw PA;McSorley SJ;Bäumler AJ;Tsolis RM
通讯作者：
Tsolis RM