利用噬菌体肽库筛选小肽免疫抑制剂

Searching for the Small Peptide Immunosuppressant in Phage Peptide Library

利用MT-2细胞系特异性表达白细胞介素2受体α(IL-2Rα)在细胞表面,作为靶蛋白在噬菌体六肽库中筛选,经过4轮筛选得到能特异性结合IL-2Rα的配体,挑选出与IL-2Rα亲和性高的21个噬菌体克隆,经过DNA测序,得到3组肽序列,其中2组序列分别与白细胞介素2(IL-2)的N端17-24(LLLDLQMI)序列和C端114-121(IVEFLNRW)序列相似,另外一组与IL-2Rβ和γ有共同的保守序列(WSXWS)相似.因此推测这些筛选到的序列可能模拟IL-2与受体α相互作用的位点和IL-2Rβ,γ与α结合的位点.根据筛选结果,进一步合成了一个九肽AIVEFLNRW,以ConA诱导的淋巴细胞转化实验为模型,观察到这个肽在终浓度≥31.3μg/mL时抑制效果明显.

Interleukin 2(IL2) and its receptor(IL2R) constitute one of the most extensively studied cytokine receptor systems. Thus, we used MT2 cells that could specifically express IL2R α on the surface to screen a random hexapeptide library and obtained the phage clones which had good combinative activities studied by Elisa. After DNA sequencing, three groups of relative peptide sequences were founded. The two groups were respectively similar to the sequence of IL2(Nterminal) at amino acids 1724 (LLLDLQMI) and the sequence of IL2(Cterminal) at amino acids 114124 (IVEFLNRW). In addition, the other group was similar to the motif (WSXWS) of IL2R β,γ. Therefore, it is inferred that these sequences might have mimicked the interaction site of IL2/IL2R and the binding site of IL2R α and β, γ. Further the synthesized peptide(AIVEFLNRW) could inhibit the T lymphocyte proliferation. These results provided the basis for the research and the development of the small peptide immunosuppressant drugs. 