PDF(Pubmed)
Abstract：
Brucella species are Gram-negative intracellular bacterial pathogens that cause the worldwide zoonotic disease brucellosis. Brucella can infect many mammals, including humans and domestic and wild animals. Brucella manipulates various host cellular processes to invade and multiply in professional and non-professional phagocytic cells. However, the host targets and their modulation by Brucella to facilitate the infection process remain obscure. Here, we report that the host ubiquitin-specific protease, USP8, negatively regulates the invasion of Brucella into macrophages through the plasma membrane receptor, CXCR4. Upon silencing or chemical inhibition of USP8, the membrane localization of the CXCR4 receptor was enriched, which augmented the invasion of Brucella into macrophages. Activation of USP8 through chemical inhibition of 14-3-3 protein affected the invasion of Brucella into macrophages. Brucella suppressed the expression of Usp8 at its early stage of infection in the infected macrophages. Furthermore, we found that only live Brucella could negatively regulate the expression of Usp8, suggesting the role of secreted effector protein of Brucella in modulating the gene expression. Subsequent studies revealed that the Brucella effector protein, TIR-domain containing protein from Brucella, TcpB, plays a significant role in downregulating the expression of Usp8 by targeting the cyclic-AMP response element-binding protein pathway. Treatment of mice with USP8 inhibitor resulted in enhanced survival of B. melitensis, whereas mice treated with CXCR4 or 14-3-3 antagonists showed a diminished bacterial load. Our experimental data demonstrate a novel role of Usp8 in the host defense against microbial intrusion. The present study provides insights into the microbial subversion of host defenses, and this information may ultimately help to develop novel therapeutic interventions for infectious diseases.
摘要：
布鲁氏菌属革兰氏阴性细胞内细菌病原体，可引起世界范围内的人畜共患疾病布鲁氏菌病。布鲁氏菌可以感染许多哺乳动物，包括人类、家畜和野生动物。布鲁氏菌操纵各种宿主细胞过程以侵入和繁殖专业和非专业吞噬细胞。然而,宿主靶标及其通过布鲁氏菌促进感染过程的调节仍然不清楚。这里,我们报道了宿主泛素特异性蛋白酶，USP8，通过质膜受体负调节布鲁氏菌对巨噬细胞的侵袭，CXCR4。在沉默或化学抑制USP8后，CXCR4受体的膜定位被富集，这增加了布鲁氏菌对巨噬细胞的入侵。通过化学抑制14-3-3蛋白激活USP8影响布鲁氏菌对巨噬细胞的侵袭。布鲁氏菌在感染巨噬细胞的感染早期抑制了Usp8的表达。此外，我们发现只有活的布鲁氏菌可以负调节Usp8的表达，提示布鲁氏菌分泌效应蛋白在调节基因表达中的作用。随后的研究表明，布鲁氏菌效应蛋白，来自布鲁氏菌的含TIR结构域的蛋白质，TcpB,通过靶向环AMP反应元件结合蛋白途径下调Usp8的表达发挥重要作用。用USP8抑制剂处理小鼠可提高B.melitensis的存活率，而用CXCR4或14-3-3拮抗剂治疗的小鼠显示细菌负荷减少。我们的实验数据证明了Usp8在宿主防御微生物入侵中的新作用。本研究提供了对宿主防御的微生物颠覆的见解，这些信息可能最终有助于开发针对传染病的新型治疗干预措施。
