宿主xCT抑制巨噬细胞内结核分枝杆菌MSH氧化的作用机制

研发新型抗结核新药是当前克服耐多药结核的重要课题。分枝硫醇(MSH)是结核分枝杆菌（结核菌）最主要的小分子量硫醇及氧化还原缓冲剂，直接影响结核菌的毒力和抗药性。氧化型MSH结核菌更容易被细胞杀死以及对药物更加敏感。我们前期发现，采用柳氮磺胺吡啶抑制宿主细胞xCT基因功能，通过降低巨噬细胞中GSH的水平显著提高氧化型MSH结核菌的数量，从而增强巨噬细胞对感染的结核菌杀灭作用，但其具体机制尚不清楚。进一步研究发现抑制xCT影响结核菌MSH氧化调控相关基因CydD/SseA等突变株的存活。基于此，我们提出假设：宿主基因xCT通过增加巨噬细胞中GSH水平、影响结核菌调控氧化相关SSeA/CydD基因的表达网络，进而抑制结核菌MSH氧化。本项目将进一步利用Crispr-Cas9、转座子测序、RNA-seq等技术，阐明宿主xCT抑制结核菌MSH氧化作用机制，为靶向xCT定向治疗结核病策略提供科学依据。

Novel drugs are urgently needed to prevent the uncontrolled development of MDR-TB. Mycothiol (MSH) which is a major low molecular weight found in Mycobacterium tuberculosis (MTB) and acts as an antioxidant to maintain the highly reducing environment within the cell, is associated with virulence and drug resistant in MTB. MTB with oxidized MSH is more sensitive to antibiotic and early to killing by macrophages. We found that disrupt of xCT by SASP enhanced the mycobateriacidal activity of macrophage through decreasing the intracellular GSH production. However, the mechanism remains unknown. we further found that disruption of xCT affected the CydD and SseA mutants’ fitness which are associated with MSH oxidation in macrophage. Based on our results, we hypotheses that xCT inhibits MSH oxidation through increasing GSH production in macrophage and affects SseA/CydD regulation network. This project will further study the mechanism of xCT inhibit MTB MSH oxidation in macrophage using Crispr-Cas9, Tn-seq and RNA-seq. The accomplishment of this study will provide novel targets and strategies to cure tuberculosis.