GC Tfp Retraction and Stress-Responsive Host Signaling

了N.淋病（GC）IV型菌毛（Tfp）是一种可伸缩的结构，其在运动性、对宿主细胞的粘附和遗传能力中起作用。收缩、伸展和底物束缚的循环使GC能够爬行（抽搐运动）并影响上皮细胞信号传导。回缩需要PilT，假设PilT用作Tfp拆卸电机。回缩经常发生并且具有相当大的力量。CG在上皮细胞表面爬行并聚集成小菌落，这些小菌落在感染期间本身可以长时间活动。从一个小菌落的Tfp收缩力计算落入生理范围内已知触发细胞反应。因此，我们使用感染的组织培养模型和遗传定义的Tfp抑制剂，测试了上皮细胞在感染期间感知和响应Tfp收缩的假设。 一对表达Tfp但不表达Opa的wt和pilT菌株。感染激活应激反应性PI-3 K/Akt途径，独立于Opa。功能性pilT强烈增强激活。感染后0.5-2小时检测到PI-3 K/Akt活化。PI-3 K的产物PIP 3易位至上皮膜的外小叶并在小菌落下方积聚。PIP 3刺激小菌落形成并增加p/VTmRNA水平。因此，Tfp回缩触发宿主产生效应物，该效应物进而影响GC运动行为。感染还影响上皮细胞基因表达。感染3小时后，超过300个上皮基因受到不同的调节，此时GC已在细胞表面形成小菌落， 尚未进入细胞的pilT在涉及MAPK途径的过程中增强这些基因的子集的表达。基因表达的pilT-ehnNavisphere的一个结果是创造了一个允许细胞承受凋亡的环境。这些pilT相关的反应可以通过磁体拉动接种在细胞上的GC膜包被的磁珠来复制。这些结果表明，Tfp收缩的力量触发了上皮细胞中的保护性应激反应途径。基于这些发现，我们提出了一个模型的作用TFP收缩上皮细胞信号。我们建议测试该模型，以更好地了解Tfp收缩在细菌发病机制中的作用。

The N. gonorrhoeas (GC) type IV pilus (Tfp) is a retractile structure that functions in motility, adherence to host cells, and genetic competence. Cycles of retraction, extension, and substrate tethering enable GC to crawl (twitching motility) and influence epithelial cell signaling. Retraction requires PilT, which is hypothesized to function as a Tfp disassembly motor. Retraction occurs often and with substantial force. CG crawl on the epithelial cell surface and aggregate into microcolonies that are themselves motile for long periods during infection. Tfp retraction forces from a microcolony is calculated to fall within the physiologic range known to trigger cellular responses. We therefore tested the hypothesis that epithelial cells sense and respond to Tfp retraction during infection, using a tissue culture model of infection and a genetically-defined pair of wt and pilT strain expressing Tfp but not Opa. Infection activates the stress-responsive PI-3K/Akt pathway, independent of Opa. A functional pilT strongly enhances activation. PI-3K/Akt activation is detected 0.5-2 hours after infection. PIP3, the product of PI-3K, translocates to the outer leaflet of the epithelial membrane and accumulates beneath microcolonies. PIP3 stimulates microcolony formation and increased p/VTmRNA levels. Thus, Tfp retraction triggers the host to produce an effector that, in turn, influences GC motility behavior. Infection also influences epithelial cell gene expression. Over 300 epithelial genes are differentially regulated after 3 hours of infection, a time when GC have formed microcolonies on the cell surface but have not yet entered the cell pilT enhances the expression of a subset of these genes, in a process that involves the MAPK pathway. One consequence of pilT-ehnancement of gene expression is the creation of an environment that allows the cell to withstand apoptosis. These pilT-related responses can be replicated by a magnet pulling on GC membrane-coated magnetic beads seeded on cells. These results suggest that the force of Tfp retraction triggers protective stress-response pathways in the epithelial cell. Based on these findings, we propose a model for the role of Tfp retraction in epithelial cell signaling. We propose to test the model to better understand the role of Tfp retraction in bacterial pathogenesis.