PDF(Pubmed)
Abstract：
Mycobacterium tuberculosis causes 6.4 million cases of tuberculosis and claims 1.6 million lives annually. Mycobacterial adhesion, invasion of host cells, and subsequent intracellular survival are crucial for the infection and dissemination process, yet the cellular mechanisms underlying these phenomena remain poorly understood. This study created a Bacillus Calmette-Guérin (BCG) transposon library using a MycomarT7 phage carrying a Himar1 Mariner transposon to identify genes related to mycobacteria adhesion and invasion. Using adhesion and invasion model screening, we found that the mutant strain B2909 lacked adhesion and invasion abilities because of an inactive fadD18 gene, which encodes a fatty-acyl CoA ligase, although the specific function of this gene remains unclear. To investigate the role of FadD18, we constructed a complementary strain and observed that fadD18 expression enhanced the colony size and promoted the formation of a stronger cord-like structure; FadD18 expression also inhibited BCG growth and reduced BCG intracellular survival in macrophages. Furthermore, FadD18 expression elevated levels of the proinflammatory cytokines IL-6, IL-1β, and TNF-α in infected macrophages by stimulating the NF-κB and MAPK signaling pathways. Overall, the FadD18 plays a key role in the adhesion and invasion abilities of mycobacteria while modulating the intracellular survival of BCG by influencing the production of proinflammatory cytokines.
摘要：
结核分枝杆菌每年导致640万例结核病，并夺走160万人的生命。分枝杆菌粘附，入侵宿主细胞，随后的细胞内存活对于感染和传播过程至关重要，然而，这些现象背后的细胞机制仍然知之甚少。这项研究使用携带Himar1Mariner转座子的MycomarT7噬菌体创建了卡介苗（BCG）转座子文库，以鉴定与分枝杆菌粘附和入侵相关的基因。使用粘附和侵入模型筛选，我们发现，突变株B2909缺乏粘附和侵袭能力，因为一个无活性的fadD18基因，编码脂酰辅酶A连接酶,尽管该基因的具体功能尚不清楚。为了研究FadD18的作用，我们构建了一个互补菌株，并观察到FadD18的表达增加了集落大小并促进了更强的索状结构的形成；FadD18的表达还抑制了BCG的生长并降低了BCG在巨噬细胞中的细胞内存活。此外，FadD18表达升高促炎细胞因子IL-6，IL-1β，通过刺激NF-κB和MAPK信号通路在感染的巨噬细胞中和TNF-α。总的来说,FadD18在分枝杆菌的粘附和侵袭能力中起关键作用，同时通过影响促炎细胞因子的产生来调节BCG的细胞内存活。
