脐血CD34+细胞分化为树突状细胞过程中JAK2、STAT5蛋白的表达及活化

目的检测脐血CD34 造血干/祖细胞分化为树突状细胞过程中JAK2、STAT5蛋白的表达及活化,从而了解JAK-STAT信号途径在CD34 造血干/祖细胞向DC分化中的作用.方法体外诱导脐血CD34 细胞向DC分化,用免疫印迹方法检测CD34 细胞、分化第7天细胞和分化第14天的细胞中与GM-CSF密切相关的JAK2和STAT5蛋白的表达及其在GM-CSF作用下蛋白酪氨酸磷酸化水平.结果分离的CD34 细胞和诱导分化第7天、第14天的细胞在正常静止状态下,均表达一定量的JAK2,而且在所有的时间点JAK2蛋白的表达量类似,随着细胞向DC分化酪氨酸磷酸化JAK2水平明显增加;STAT5在CD34 细胞分化前即有明显表达,随着向DC分化,其表达量增加.随着DC的分化成熟,STAT5的酪氨酸磷酸化水平提高.STAT5的活化高峰较JAK2的酪氨酸磷酸化滞后.结论 JAK-STAT途径可能参与了GM-CSF刺激作用下CD34 细胞诱导向DC分化的调控机制.

Expressions and activation of JAK2 and STAT5 during the process of differentiation of human cord blood CD34+ cells into dendritic cells

Objective To understand the roles of JAK STAT pathway in the process of differentiation of human cord blood CD34 hematopoietic stem cells into dendritic cells (DCs) by detecting the expressions and activation of JAK2 and STAT5. Methods CD34 hematopoietic stem cells isolated from human umbilical cord blood and cultured for two weeks were induced to differentiate into DCs in vitro . Total cellular JAK2 and STAT5 and tyrosine phosphorylated protein stimulated by granulocyte/macrophage colony stimulating factor (GM CSF) at different time points (0, 7, and 14) during DC differentiation were detected by Western blotting. Results The amount of JAK2 protein was similar at 0, 7, and 14 d without GM CSF stimulation. With the differentiation of cells into DCs, the amount of tyrosine phospho JAK2 induced by GM CSF increased markedly. Both total cellular and tyrosine phospho STAT5 expression increased markedly during DC differentiation. Maximal tyrosine phospho STAT5 expression was later than JAK2. Conclusion JAK STAT pathway may take part in the signal mechanism of DCs differentiation from CD34 hematopoietic stem cells stimulated by GM CSF.