酪氨酸蛋白激酶JAK1 在IL-6诱导JAK/STAT 途径活化中的作用

目的 酪氨酸蛋白激酶JAK1和转录因子STAT3为参与IL－6诱导的JAK／STAT信号转导途径的两种主要的信号蛋白分子。本研究试图揭示JAK1在JAK／STAT途径诱导活化中的作用。方法 分别采用凝胶阻滞电泳（EMSA）和免疫沉淀（IP）法观察IL－6刺激作用下STAT3和JAK1在3种骨髓瘤细胞系（XG－7，KM－3和Sko-007)中的诱导活化状态。采用RTPCR和Western-blot法检测这两种信号蛋白分子在以上3株靶细胞中的表达情况。结果 尽管SAT3在3株靶细胞中都能够正常表达，但只有Sko-007细胞中出现IL－6刺激作用下STAT3的诱导活化。在XG－7细胞中，既没有检测到JAK1的表达，也没有观察到JAK1的活化。尽管JAK1在KM－3细胞中能够正常表达，但不能被IL－6诱导激活。Sko-007细胞中则同时出现JAK1的表达及IL－6刺激后的诱导活化。结论 JAK1的正常表达和激活是IL－6刺激作用下JAK／STAT信号转导途径在骨髓瘤细胞中诱导活化的前提条件。

Function of tyrosine kinase JAK1 in IL-6-induced activation of JAK/STAT signal transduction pathway

Aim Protein tyrosine kinase JAKI and transcrip- tion factor STAT3 are two major signaling molecules involving in IL- 6- induced JAK/STAT signal transduction pathway. The aim of this study is to investigate the function of JAKI in IL- 6- in- duced JAK/STAT pathway activation in human myeloma cell lines. Methods Electrophoretic mobility shift assay ( EMSA) and immunoprecipitation ( IP) were used respectively to detect the activation states of STAT3 and JAK1 in three human myeloma cell lines- XG- 7, KM- 3 and Sko- 007 in the presence of IL- 6. And the expression of these two signaling molecules in the cells were analyzed by RT- PCR and Western -blot. Results Al- though almost equal amount of STAT3 were expressed in three myeloma cell lines, the activation of STAT3 only appeared in Sko- 007 cells stimulated by IL- 6. Moreover,we observed neither expression nor activation of JAK1 in XG- 7 cells; and in KM- 3 cells, there was normal expression but no activation of JAK1 ; but in Sko- 007 cells, both expression and activation of JAK1 were seen simultaneously. Conclusions IL- 6- induced activation of JAK/STAT pathway in human myeloma cells requires expression and activation of JAK1 protein tyrosine kinase.