刚地弓形虫棒状体蛋白17激活活化蛋白1信号抑制小鼠巨噬细胞凋亡

Toxoplasma gondii Rhoptry Protein 17 Inhibits the Apoptosis of Mouse Macrophages via Activation of Activator Protein 1 Signaling

目的检测刚地弓形虫(Toxoplasma gondii)棒状体蛋白17(rhoptry protein 17,ROP17)对γ干扰素(IFN-γ)诱导的小鼠单核巨噬细胞(J774A.1)凋亡的调控作用。方法将重组质粒p3×Flag-CMV-14/Tg ROP17和p3×Flag-CMV-14空质粒(对照组)转染J774A.1细胞后,加入重组IFN-γ诱导细胞凋亡,通过流式细胞术和蛋白质印迹(Western blotting)检测ROP17对细胞凋亡的调控作用,检测c-Jun磷酸化水平及活化形式的半胱天冬酶3(Caspase 3)、Bcl-2、Bcl-x L和Bcl-3等凋亡相关蛋白的表达情况。J774A.1细胞共转染p3×FlagCMV-14/Tg ROP17和c-Jun sh RNA,加入重组IFN-γ诱导细胞凋亡,Western blotting检测ROP17对凋亡的调控作用及凋亡相关蛋白Bcl-3的表达。结果流式细胞术显示,过表达ROP17组细胞凋亡率为(3.73±0.51)%,明显低于对照组的(7.78±1.10)%(P<0.05)。Western blotting结果显示,过表达ROP17组磷酸化c-Jun蛋白相对表达量为0.196±0.028,对照组为0.075±0.010(P<0.05);Bcl-3相对表达量为0.461±0.063,对照组为0.108±0.013(P<0.05)。活化形式的Caspase 3相对表达量为0.015±0.004,对照组为0.174±0.026(P<0.05)。Bcl-2在过表达ROP17组和对照组中的相对表达量分别为0.119±0.013和0.117±0.018,Bcl-x L则分别为0.124±0.015和0.121±0.023,差异均无统计学意义(P>0.05)。在c-Jun sh RNA有效抑制c-Jun及其磷酸化表达的条件下,活化形式的Caspase 3在RNA干扰组和对照组的相对表达量分别为0.147±0.024和0.087±0.010(P<0.05),Bcl-3则分别为0.085±0.010和0.162±0.011(P<0.05)。结论ROP17抑制IFN-γ诱导的J774A.1细胞凋亡依赖于c-Jun的磷酸化及Bcl-3的表达。

Objective To investigate the effect of Toxoplasma gondii rhoptry protein 17（ROP17） on γ-interferon（IFN-γ）-induced apoptosis of mouse J774A.1 monocyte macrophages. Methods The J774A.1 cells were transfected with recombinant plasmid p3×Flag-CMV-14/TgROP17 or empty plasmid p3×Flag-CMV-14. After addition of IFN-γ, flow cytometry and Western blotting were performed to detect apoptosis and the protein levels of phosphorylated c-Jun and apoptosis-related proteins cleaved Caspase-3, Bcl-2, Bcl-xL and Bcl-3. The p3×Flag-CMV-14/TgROP17 plasmid and c-Jun shRNA were co-transfected into J774A.1 cells, after which IFN-γ was added to induce cell apoptosis. The levels of cleaved Caspase-3 and Bcl-3 were analyzed using Western blotting. Results Flow cytometry showed that the apoptosis rate of cells overexpressing ROP17[（3.73±0.51）%] was significantly lower than that of the control cells[（7.78±1.10）%, P〈0.05]. Western blotting showed significant differences in protein levels of phosphorylated c-Jun（0.196±0.028 vs. 0.075±0.010）, Bcl-3（0.461±0.063 vs. 0.108±0.013） and cleaved Caspase 3（0.015±0.004 vs. 0.174±0.026） between the cells overexpressing ROP17 and control cells （all P〈0.05）. However, the levels of Bcl-2 and Bcl-xL were not significantly different between the cells overexpressing ROP17 and the control. When the expression of c-Jun and phosphorylation of c-Jun were inhibited by c-Jun shRNA, the relative level of cleaved Caspase 3 in the RNA interferenced cells and control cells was 0.147±0.024 and 0.087±0.010, respectively（P〈0.05）, and the relative level of Bcl-3 was 0.085±0.010 and 0.162±0.011, respectively（P〈0.05）. Conclusion The anti-apoptosis effect of ROP17 is dependent on the phosphorylation of c-Jun and the expression of Bcl-3.