Dependence of RIG-I Nucleic Acid-Binding and ATP Hydrolysis on Activation of Type I Interferon Response

Exogenous nucleic acids induce an innate immune response in mammalian host cells through activation of the retinoic acid-inducible gene I (RIG-I). We evaluated RIG-I protein for RNA binding and ATPase stimulation with RNA ligands to investigate the correlation with the extent of immune response through RIG-I activation in cells. RIG-I protein favored blunt-ended, double-stranded RNA (dsRNA) ligands over sticky-ended dsRNA. Moreover, the presence of the 5'-triphosphate (5'-ppp) moiety in dsRNA further enhanced binding affinity to RIG-I. Two structural motifs in RNA, blunt ends in dsRNA and 5'-ppp, stimulated the ATP hydrolysis activity of RIG-I. These structural motifs also strongly induced IFN expression as an innate immune response in cells. Therefore, we suggest that IFN induction through RIG-I activation is mainly determined by structural motifs in dsRNA that increase its affinity for RIG-I protein and stimulate ATPase activity in RIG-I.

Inducement Effect of Interferon Alpha on Apoptosis of Rat Vascular Smooth Muscle Cells via P204 and RAS Signal Pathway / 医药导报

Objective To investigate the effect of interferon alpha ( IFN-α) on apoptosis of vascular smooth muscle cells ( VSMCs) in rats and the related mechanism. Methods The cells were divided into three group:group A, group B and group C.Group A was transfected with nonspecific siRNA, group B was intervened with IFN-α and transfected with nonspecific siRNA, and group C was intervened with IFN-α and transfected with IFI204 siRNA. All the cells were cultured for 48 h. The expression of P204 mRNA was determined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR).P204, RAS protein levels, and phosphorylation levels of RAF and ERK were analyzed by Western blotting. The cell apoptosis was analyzed by flow cytometry with Annexin-V FITC/PI method. Results As compared with group A, the expression of P204 mRNA and protein in group B was up-regulated (P<0.05), the cell apoptosis was increased (P<0.05), in the process of the above, the expression of RAS protein was decreased ( P<0.05) and the phosphorylation levels of RAF and ERK were dropped (P<0.05).In group C, the expression levels of P204 mRNA and protein were down-regulated (P<0.05), and cell apoptosis was decreased ( P<0.05) , the expression of RAS protein and the phosphorylation levels of RAF and ERK were increased ( P<0.05) . Conclusion P204 and RAS signal pathway participates in IFN-α regulation of apoptosis of VSMCs in rats.