Knowles Alex A, Campbell Susan G, Cross Neil A, Stafford Prachi
Biomolecular Sciences Research Centre, Department of Biosciences and Chemistry, Faculty of Health and Wellbeing, Sheffield Hallam University, Sheffield S1 1WB, UK.
Microorganisms. 2023 Feb 27;11(3):606. doi: 10.3390/microorganisms11030606.
contributes to the chronic oral disease periodontitis, triggering the activation of host inflammatory responses, inducing cellular stresses such as oxidation. During stress, host cells can activate the Integrated Stress Response (ISR), a pathway which determines cellular fate, by either downregulating protein synthesis and initiating a stress-response gene expression program, or by initiating programmed cell death. Recent studies have implicated the ISR within both host antimicrobial defenses and the pathomechanism of certain microbes. In this study, using a combination of immunofluorescence confocal microscopy and immunoblotting, the molecular mechanisms by which infection alters translation attenuation during oxidative stress-induced activation of the ISR in oral epithelial cells were investigated. infection alone did not result in ISR activation. In contrast, infection coupled with stress caused differential stress granule formation and composition. Infection heightened stress-induced translational repression independently of core ISR mediators. Heightened translational repression during stress was observed with both -conditioned media and outer membrane vesicles, implicating a secretory factor in this exacerbated translational repression. The effects of gingipain inhibitors and gingipain-deficient mutants confirmed these pathogen-specific proteases as the effector of exacerbated translational repression. Gingipains are known to degrade the mammalian target of rapamycin (mTOR) and the findings of this study implicate the gingipain-mTOR axis as the effector of host translational dysregulation during stress.
导致慢性口腔疾病牙周炎，引发宿主炎症反应的激活，诱导诸如氧化等细胞应激。在应激期间，宿主细胞可以激活综合应激反应（ISR），这是一条决定细胞命运的途径，通过下调蛋白质合成并启动应激反应基因表达程序，或者通过启动程序性细胞死亡来实现。最近的研究表明ISR既参与宿主抗菌防御，也参与某些微生物的发病机制。在本研究中，使用免疫荧光共聚焦显微镜和免疫印迹相结合的方法，研究了感染在口腔上皮细胞氧化应激诱导的ISR激活过程中改变翻译衰减的分子机制。单独感染不会导致ISR激活。相反，感染与应激相结合会导致不同的应激颗粒形成和组成。感染增强了应激诱导的翻译抑制，且与核心ISR介质无关。在用条件培养基和外膜囊泡处理时均观察到应激期间翻译抑制增强，这表明一种分泌因子参与了这种加剧的翻译抑制。牙龈蛋白酶抑制剂和牙龈蛋白酶缺陷突变体的作用证实了这些病原体特异性蛋白酶是加剧翻译抑制的效应物。已知牙龈蛋白酶会降解雷帕霉素的哺乳动物靶标（mTOR），本研究结果表明牙龈蛋白酶-mTOR轴是应激期间宿主翻译失调的效应物。
