HIPK2在IL-2撤除诱导T细胞凋亡中的作用

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

目的研究同源结构域相关的蛋白激酶2(homeodomain-interacting protein kinase2,HIPK2)在白介素2(interleukin2,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Bi m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Bi m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-2T细胞凋亡,这种作用可能与HIPK2上调促凋亡基因Bi m和下调抗凋亡基因Bcl-xL的表达相关。

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-xL 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-xL 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-xL.