Crosstalk between Arl8a and TLR4 Signaling in Dendritic Cells

Abstract: To elucidate the crosstalk between Arl8a and two downstream pathways of TLR4 signaling in dendritic cells (DCs)， we silenced guanine nucleotide-exchange factors H1 (GEFH1) and Arl8a in DCs from wild-type (WT) mice with small interference RNAs (siRNA)， and examined the mRNA levels of MYH9 which was targeted by RhoB in TLR4-TRIF pathway， with or without LPS stimulation. Then， we used Real-time PCR to detect Arl8a mRNA level in LPS stimulated DCs isolated from wild-type and IFNα/β receptor knockout mice (IFNα/β RKO). We also analyzed IL-6 and IL-12a mRNA expression in DCs after Arl8a silenced by siRNA. The results showed that Arl8a and GEFH1 siRNA significantly suppressed the LPS-mediated up-regulation of MYH9 mRNA (P<0.01). In addition， the up-regulation of Arl8a mRNA was observed in DC from WT mice but not in DC from IFNα/β RKO after LPS incubation， indicating that LPS-induced up-regulation of Arl8a was attenuated by knockout of IFNα/β receptor. However， Arl8a siRNA failed to alter IL-6 and IL-12a mRNA level in DC after LPS stimulation. In conclusion， GEFH1 and RhoB were proved to be able to regulate MYH9 expression， while the Arl8a level could be modified by TRIF-IFNβ pathway in DC. There was no evidence that Arl8a is involved in MyD88-dependent signaling induced cytokines IL-6 and IL-12a expression.

CSTR: 32200.14.cjcb.2014.06.0011