Research On The Regulation Of Rab7on TLR-7Activated Interferon-I Expression In Macrophages

As an important kind of pattern recognition receptors, Toll-like receptors can recognize specific structural components and metabolites in most of pathogenic microorganism.Normal activation of TLR can not only initiate innate immunity but also adaptive immunity. Abnormal over-activation of TLRs may cause autoimmune diseases, such as rheumatoid arthritis and systemic lupus erythematosus. Studies have show, the completion of TLRs in addition to start the innate immune response. TLR7is localized in endosome membrane surface and regulate endocytosis in cell. Endocytosis is involved in the activation of TLR7signaling. We speculate that Rab7may take part in TLR7signal transduction pathway. Objective:To study the effects of Rab7on TLR7signaling. Methods:The production of IFN-a, IFN-β, IL-6, TNF-α, IP-10were measured by RT-PCR, Real-Time PCR after transformed cell lines of Rab7, Rab7T22N, stimulated with R848for6h. Rab7-siRNA was also synthesized, and transient transfected into RAW264.7cell. The interference effect was detected by Real time-PCR. After stimulation with R848for6h, we detected interferon (IFN) and other cytokine expression by Real-Time PCR. The expression of p-ERK, p-JNK and p-p38was measured by Western blot. Results:After stimulated by R848, the expression of Rab7mRNA was significantly improved at6h. Over-expression of Rab7inhibited the production of IFN-a, IFN-β, IL-6, TNF-a. The production of cytokines were recovered in cells stably expressing Rab7T22N. However, there is no significant effect on the expression of IP-10mRNA. After Rab7siRNA transfection, the expression of Rab7mRNA was obviously reduced, with the expression of IFN-a, IFN-(3, IL-6and TNF-a significantly increased. We found that p-ERK, p-JNK and p-p38phosphorylation level increased in macrophages after Rab7silencing. Conclusion:Rab7is a negative regulator protein in TLR7signaling pathways. Rab7can inhibited R848-induced MAPK activation. This study may lay a foundation for further study the role of Rab proteins in TLRs signaling pathways.