mIL-4-SA双功能融合蛋白的制备和活性测定

Preparation and bioactivity assay of mIL-4-SA fusion protein

目的制备链亲和素标记的鼠白介素4(mIL-4-SA)融合蛋白,并研究其生物学功能。方法通过RT-PCR克隆mIL-4基因,构建mIL-4-SA-pET21表达质粒,并转化到大肠杆菌BL21(DE3)中,经IPTG诱导表达,对表达的融合蛋白采用镍金属螯合(Ni-NTA)色谱柱纯化、透析复性。MTT法检测融合蛋白对C57小鼠胸腺细胞的增殖作用,流式细胞仪分析融合蛋白对生物素化的B16F10细胞锚定修饰率。结果成功构建了mIL4-SA-pET21质粒,并在大肠杆菌中实现高效表达,表达量达菌体总蛋白质的35%,纯化后的mIL-4-SA融合蛋白纯度达95%,并具有双重活性,即mIL-4对C57小鼠胸腺细胞具有增殖作用和SA介导的高效结合至已生物素化的B16F10肿瘤细胞表面的功能(表面锚定修饰效率96.69%)。结论研制的mIL-4-SA融合蛋白具有双重活性,可为研制表面修饰的新型肿瘤细胞疫苗提供基础。

Purpose To prepare streptavidin-tagged mouse interleukin-4（mIL-4-SA） bifunctional fusion protein and to study on its bioactivity.Methods The mIL-4 gene was cloned by RT-PCR and cloned into pET21 vector to get mIL-4-SA-pET21 expression plasmid.The mIL-4-SA fusion protein was expressed in BL21（DE3） host bacteria and purified through the Ni-NTA affinity chromatography and refolded by dilution and dialysis.The effect of mIL-4-SA fusion protein on mouse thymocytes proliferation was evaluated by MTT.Flow cytometric analysis was performed to detect the mIL-4-SA fusion protein on the biotinylated B16F10 tumor cells.Results The mIL-4-SA-pET21 vector was successful by constructed and the mIL-4-SA fusion protein was expressed in BL21（DE3） at about 35% of total bacterial proteins.The purity of mIL-4-SA was about 95% through Ni-NTA.The mIL-4-SA fusion protein exhibited bifunctional activities,i.e.,stimulative effect for mouse thymocyte proliferation and SA-mediated high-affinity binding to biotinylated cell surfaces （anchoring modified rate was about 96.69%）.Conclusion The mIL-4-SA fusion protein was expected to be developed for the treatment of tumors.