HIPK2在IL-2撤除诱导T细胞凋亡中的作用

目的 研究同源结构域相关的蛋白激酶2（homeodomain-interacting protein kinase 2,HIPK2）在白介素2（interleukin 2,IL-2）撤除诱导的T细胞凋亡中的表达及其作用.方法 IL-2依赖性的T细胞株（CTLL-2）,撤除IL-2后可诱导凋亡.运用PI染色和DNA凝胶电泳检测细胞凋亡,实时定量RT-PCR检测HIPK2及其他细胞凋亡相关基因的表达.通过反义技术下调HIPK2的表达,观察HIPK2在IL-2撤除诱导的T细胞凋亡中的作用.结果 随IL-2撤除时间延长,CTLL-2细胞凋亡率增加,细胞基因组DNA发生了明显片段化.参与死亡受体凋亡途径的基因FasL和Fas表达没有明显改变（P＞0.05）,Bcl-2家族中促凋亡基因Bim表达明显上调（P＜0.01）,抗凋亡基因Bcl-xL表达明显下调（P＜0.05）,HIPK2表达明显上调（P＜0.05）.下调HIPK2的表达可以显著降低CTLL-2在IL-2撤除后的细胞凋亡率（P＜0.01）,促凋亡基因Bim的表达被显著下调（P＜0.01）,而抗凋亡基因Bcl-xL明显上调（P＜0.05）.结论 HIPK2可以促进IL-2撤除诱导的CTLL-2 T细胞凋亡,这种作用可能与HIPK2上调促凋亡基因Bim和下调抗凋亡基因Bcl-xL的表达相关.

Role of HIPK2 in the Apoptosis of T Lymphocytes Induced by Deprivation of IL-2

Purpose This study was designed to investigate the role of homeodomain-interacting protein kinase 2(HIPK2) in the apoptosis of T lymphocytes which was mediated by the deprivation of cytokine. Methods CTLL-2,interleukin-2(IL-2)-dependent T lymphocytes, was deprived of IL-2 to induce apoptosis. Apoptotic cells were quantified by the measurement of the hypodiploid area in the PI-staining profiles. Apoptosis of CTLL-2 was also determined by DNA fragmentation analysis after agarose gel electrophoresis. The expression of genes involved in apoptosis was detected by real-time quantitative RT-PCR.Antisense technology was applied to suppress the expression of HIPK2 in order to investigate the role of HIPK2 in the apoptosis of CTLL-2 mediated by the deprivation of IL-2. Results The percentage of apoptotic CTLL-2 increased over time with IL-2 deprivation, which resulted in detectable DNA ladder. Analysis of the gene expression involved in the apoptosis of CTLL-2 revealed that there was no change found for Fas or FasL (P>0.05) . However, the expression of Bim was increased(P<0.01)and the expression of Bcl-x_L was decreased(P<0.05). The up-regulation of HIPK2 was also found(P<0.05). After the expression of HIPK2 was down-regulated, the percentage of apoptotic CTLL-2 decreased consequently(P<0.01). In addition, the expression of Bim decreased(P<0.01)and that of Bcl-x_L increased (P<0.05). Conclusions HIPK2 promoted the apoptosis of CTLL-2 deprived of IL-2, which was associated with the increased expression of Bim and the decreased expression of Bcl-x_L.