Arl8a与树突状细胞TLR4-TRIF信号途径的相关性

Relationship of the Arl8a with TLR4-TRIF pathway in dendritic cells

目的 探讨ADP-核糖基化因子样8A（ADP-ribosylation factor-like 8A,Arl8a）与树突状细胞（dendritic cell,DC）中TLR4-TRIF-GEFH1-RhoB信号途径的相关性.方法 从野生型和TRIF敲除基因（TRIFKO）小鼠中分离和培养DC,LPS刺激后收集细胞扩增总cDNA,通过实时定量PCR检测Arl8a的mRNA表达.然后用鸟嘌呤核苷酸交换因子H1（GEFH1）的siRNA转染来自野生型小鼠的DC,进行LPS刺激或未刺激处理并检测Arl8a的mRNA表达.再用GEFH1和Arl8a的siRNA转染DC,LPS刺激后检测RhoB的mRNA表达.结果 在LPS刺激后,Arl8a的mRNA表达在野生型小鼠的DC中增加,在TRIFKO小鼠的DC中则未被上调.此外,在野生型小鼠中Arl8a的mRNA上调可被GEFH1的siRNA明显抑制（P＜0.01）.而Arl8a和GEFH1的siRNA均能显著抑制RhoB的mRNA表达（P＜0.01）.结论 Arl8a的表达与DC的TRL4-TRIF途径有关,并且在转录水平与GEFH1和RhoB相关.

Objective To explore the relationship of the ADP-ribosylation factor-like 8A （Arl8a）with TLR4-TRIF-GEFH1 -RhoB pathway in dendritic cells（DCs）. Methods DCs were prepared from wildtype and TRIF-knockout （TRIFKO） mice. After LPS stimulation, the cells were collected for cDNA amplification. Real-time PCR method was used to detect Arl8a mRNA levels. DCs from wild-type mice were transfected with guanine nucleotide-exchange factors H1 （ GEFH1 ） small interference RNA （ siRNA ）, Arl8a mRNA levels were examined with or without LPS stimulation. Then RhoB mRNA expression was analyzed in DCs transfected with the siRNA of GEFH1 and Arl8a gene, respectively. Results LPS induced the up-regulation of Arl8a mRNA in DCs from control mice but not in DCs from TRIFKO, indicating that LPS-mediated up-regulation of Arl8a was suppressed in TRIFKO DCs. In addition, siRNA of GEFH1 significantly suppressed the LPS-mediated up-regulation of Arl8a mRNA, RNAi of Arl8a and GEFH1 significantly decreased RhoB mRNA level in DCs after LPS stimulation （ P 〈 0. 01 ）. Conclusion The expression of Arl8a is involved in the TLR4-TRIF pathway in DCs, and Arl8a is closely associated with GEFH1 and RhoB at transcriptional level.