呼吸道合胞病毒(RSV)对干扰素(IFN)信号通路STAT蛋白核转移的影响

 目的 研究呼吸合胞病毒(respiratory syncytial virus,RSV)感染小鼠骨髓树突状细胞(bone marrow derived dendritic cells,BMDCs)后,对Ⅰ型和Ⅱ型干扰素(interferon,IFN)诱导的JAK/STAT通路蛋白活化后核转移的影响。方法 从BALB/c小鼠的长骨中分离骨髓细胞,经过培养和刺激后得到BMDCs。将BMDCs接种于带小室的玻片上,以感染复数(multiplicity of infection,MOI)为1的RSV感染细胞,并设紫外线灭活的RSV(UV-RSV)和培养液(media)刺激为对照。在培养24 h后,分别用100 IU/mL的IFN-β刺激30 min或0.64 pmol/L的IFN-γ刺激45 min,然后进行免疫荧光染色。在荧光显微镜下计数STAT蛋白核转移阳性细胞的百分比,比较各组间的差异。结果 在未感染的BMDCs中,STAT1和STAT2蛋白主要存在于细胞质中,当用IFN-β 刺激BMDCs后可见到明显的STAT1和STAT2蛋白向细胞核转移,核转移阳性细胞百分比分别为89.0%±4.6%和83.7%±5.1%,与未处理组(NT组)相比有明显差异(P<0.01)。而RSV感染后,发现STAT1和STAT2蛋白核转移阳性细胞数较IFN-β 刺激组明显减少(P<0.01),说明RSV感染可以抑制IFN-β诱导的STAT1和STAT2蛋白的核转移。而应用UV-RSV感染后与IFN-β刺激组相比,STAT1和STAT2蛋白核转移阳性细胞数却未见明显减少(P>0.05)。用IFN-γ 刺激BMDCs后也可见到明显的STAT1蛋白向细胞核转移(阳性细胞为85.3%±6.4%);而RSV感染后与IFN-γ刺激组相比,STAT1核转移阳性细胞数(79.3%±4.9%)却未见明显减少(P>0.05)。结论 RSV感染BMDCs后,能特异性地抑制Ⅰ型IFN诱导的STAT1和STAT2蛋白的核转移,而对II型IFN诱导的STAT1蛋白的核转移却没有影响。

The effects of respiratory syncytial virus(RSV) on nuclear translocation of STAT proteins of interferon(IFN) signal pathways

Objective To study the effects of respiratory syncytial virus(RSV) on nuclear translocation of STAT proteins of interferon(IFN) signal pathways in mouse bone marrow derived dendritic cells(BMDCs).Methods Bone marrow(BM) cells were collected from long bones of BALB/c mice.BMDCs were developed after culturing and stimulating for 6 days,and then were grown on glass chamber slides.After infected with mock,RSV(multiplicity of infection=1) or ultraviolet(UV) inactivated RSV for 24 h,BMDCs were subsequently treated with media,IFN-β(100 U/mL for 30 min) or IFN-γ(0.64 pmol/L for 45min).Following treatments,cells were fixed and stained by immunofluorescence.Fluorescence microscopy was used to observe the changes of positive cells which had nuclear localizations of STAT proteins induced by different IFNs after RSV infection.Results In mock-infected BMDCs,STAT1 and STAT2 were predominantly present in the cytoplasm.Treatment with IFN-β resulted in marked redistribution of STAT1 and STAT2 to the nucleus.The positive cells which had nuclear localizations of STAT1(89.0%±4.6%) and STAT2(83.7%±5.1%) were more than those of no treatment groups(P<0.01).However,treatment of RSV-infected BMDCs with IFN-β did not result in redistribution of STAT1 and STAT2 into the nucleus.The positive cells significantly decreased compared with IFN-β treatment groups(P<0.01).When RSV was inactivated by ultraviolet before infection,the positive cells had no significant difference compared with IFN-β treatment groups(P>0.05).Treatment with IFN-γ in mock-infected BMDCs also resulted in marked redistribution of STAT1 to the nucleus(the positive cells were 85.3%±6.4%).Interestingly,treatment of RSV-infected BMDCs with IFN-γ,the positive cells(79.3%±4.9%) had no significant changes compared with mock-infected BMDCs(P>0.05).Conclusions RSV infection could specifically inhibit type I IFN induced nuclear translocations of STAT1 and STAT2,instead of affecting IFN-γ-mediated STAT1 nuclear translocation.