Rab7 Negatively Regulates TLR-3 Signlaing Pathway In A C-terminal Dependent Manner

TLR-3 is a member of the pattern recognition receptor TLR receptor family for dsRNA recognition. The recognition initiates innate immune responses. However, abnormal or excessive activation of TLR-3 can lead to physiological function disorder and the occurrence of diseases. Rab7 is a kind of small G protein locating in late endosome/lysosome. Recent research has shown that Rab7 is involved in a variety of signal transduction processes. The research on the regulation of Rab7 on endosomal TLR-3 signal transduction is less. The purpose of this paper is to investigate the role and mechanisms of Rab7 on TLR-3 signal transduction. Methods:Rab7 was silenced by siRNA. TLR-3 mRNA expression level was detected by Real-time PCR after Rab7 was silenced. After Rab7 gene silencing, PolyI:C-induced of TNF-a, IL-1β, IFN-a, IFN-β and IP-10.was detected by Real-time PCR. The phosphorylation level of ERK, JNK and p38 in the MAPK signal transduction pathway was detected by Western blot. The plasmids of Rab7 eukaryotic expression vector and C-terminal missing vector Rab7 △ C was transfected into RAW26.7 cells and the stable cell line expressing Rab7 and its mutant was established. Using these cell lines as model, the expression of TNF-a, IL-1β, IFN-a, IFN-β and IP-10 was measured after polyI:C stimulation for different time. The change of the MAPK signal transduction pathway was analyzed by Western blot. Results:Rab7 gene silencing significantly promoted TLR3 mRNA expression and polyI:C-induced TNF-a, IL-1β, IFN-a, IFN-β and IP-10 mRNA expression (p<0.05). Rab7 gene silencing promoted polyl:C-induced phosphorylation of ERK and p38. Rab7 overexpression significantly inhibited polyI:C-induced TNF-a, IL-1β, IFN-a, IFN-β and IP-10 mRNA expression. Transfection of Rab7△C resulted in significantly elevated expression of polyl:C-induced cytokines. Western Blot results showed transfection of Rab7AC significantly promoted polyl:C-induced phosphorylation of ERK, JNK, and p38. Conclusion:Rab7 negatively regulates TLR-3 signlaing pathway in a C-terminal dependent manner.