人类IL-3受体α亚单位与小鼠AIC2B蛋白的相互作用

Interaction of the Human IL-3 Receptor α Subunit with the Murine AIC2B

目的 探索人类IL - 3受体 (IL - 3R)α亚单位与小鼠内源性AIC2B蛋白在诱导细胞增殖信号表达过程中的相互作用。方法 通过PCR扩增技术 ,构建了IL - 3Rα亚单位胞浆域缺失突变子 34、2 2和CD ,然后将野生型和突变型IL - 3Rα亚单位cDNA分别转染到含小鼠IL - 3R基因表达的BaF3细胞 ,并检测了阳性转染子的增殖信号传导和酪氨酸磷酸化。结果 表达野生型hIL - 3Rα/ βc的BaF3阳性对照克隆在生理浓度hIL - 3诱导后即可出现细胞增殖和胞浆信号蛋白 βc、Jak2及Shc磷酸化 ;而含野生型IL - 3Rα亚单位和AIC2B的BaF3细胞可出现高浓度hIL - 3刺激的细胞增殖反应 ,但无信号传导分子的活化 ;共表达突变型IL - 3Rα与AIC2B的BaF3细胞及未转染的BaF3细胞则对各种浓度的hIL - 3刺激均无反应。结论 尽管hIL - 3Rβc亚单位在hIL - 3诱导的信号传导过程中担负关键作用 ,但小鼠内源性AIC2B也可与hIL - 3Rα重建功能性hIL - 3R ,这种功能的表达需要hIL -

Objective To investigate the interaction of the human interleukin-3 receptor (hIL-3R) α subunit with the AIC2B protein of murine endogeneous IL-3R β sununit in reducing the expression of the proliferating signal.Mehtods The cytoplasmic deletion mutants(34,22 and CD) of hIL-3R α subunit were generated by PCR amplification technique. BaF3 cells which express mouse IL-3R were transfected with either wild-type or mutant hIL-3R α cDNA and hIL-3 stimulated proliferative signal transduction and tyrosine phosphorylation of the positive transfectants were examined.Results Cell proliferation and activation of the cytoplasmic β c、Jak2 and Shc proteins of BaF3 clone co-expressed hIL-3R α/β,as the postive contrast,could be induced by physiologic concerntration of hIL-3 and BaF3 cells expressed wild-type hIL-3R α clone could confer a growth response to high concerntration of hIL-3,but fail to activate β c、Jak2 and Shc proteins despite containing endogeneous AIC2B. Untransfected or transfected BaF3 clone expressed mutant hIL-3R α failed to proliferate and show ligand-induced tyrosine phosphorylation of above signal molecules in the presence of hIL-3 with various concerntration.Conclusions Human β c is critical for hIL-3 signaling,but hIL-3R α can reconstitute a functional receptor for hIL-3 with mouse endogeneous AIC2B protein and the entire structure of hIL-3R α is essential for the functional expression of this reconstitutive receptor.