OmpR对伤寒沙门菌侵袭上皮细胞能力的影响

目的: 研究OmpR对伤寒沙门菌侵袭力的影响及相关分子机制。方法: 利用空载体对照株(WT pBAD33)、ompR缺陷株(ΔompR pBAD33)和ompR回补株(C ΔompR)进行HeLa细胞侵袭实验，探究伤寒沙门菌OmpR对于HeLa细胞侵袭力的影响。进一步用荧光实时定量PCR(qRT PCR)、凝胶阻滞实验(EMSA)分析伤寒沙门菌OmpR对侵袭相关基因iagA、invF、prgH的调控作用。结果： 成功制备伤寒沙门菌C ΔompR。在HeLa细胞侵袭实验中，ΔompR pBAD33侵袭力显著低于WT pBAD33(P<0.01)，而C ΔompR侵袭能力较ΔompR pBAD33明显升高（P<0.01）；qRT PCR结果显示，ΔompR pBAD33中侵袭相关基因iagA、invF、prgH的转录水平较WT pBAD33明显下降(P<0.01)；EMSA结果表明，OmpR可直接与prgH基因启动子区域结合，与iagA和invF基因启动子区域未有结合。 结论： OmpR通过直接调节prgH和间接调节iagA、invF增加侵袭相关基因的表达，从而增强伤寒沙门菌对上皮细胞的侵袭力。

Effect of OmpR on the invasion of Salmonella enterica serovar Typhi

Objective: To investigate the effect of OmpR on the invasion of Salmonella enterica serovar Typhi(S. Typhi) and its potential mechanism. Methods: The invasion of S. Typhi were investigated by using cell invasion experiment with the empty vector strain(WT pBAD33), the ompR deletion mutant strain(ΔompR pBAD33) and the ompR complementary strain(C ΔompR). In addition, qRT PCR and EMSA were used to analyze the regulation of OmpR on the expression of invasion related genes iagA, invF and prgH. Results: In the invasion assay, ΔompR pBAD33 showed significantly weaker invasion than that of WT pBAD33(P<0.01)，and the invasion of C ΔompR was higher than that of ΔompR pBAD33(P<0.01); expressional levels of invasion related genes in ΔompR pBAD33 were lower than those in WT pBAD33(P<0.01). EMSA results showed that OmpR bound to the promoter region of prgH in a dose dependent manner, but it was unable to bind to the upstream regions of iagA and invF. Conclusion: OmpR promotes the invasion of S. Typhi, which results from up regulating the expression of invasion related genes by directly regulating prgH, indirectly regulating iagA and invF.