Antiapoptotic function of 17AA(+) WT1 (Wilms' tumor gene) isoforms on the intrinsic apoptosis pathway
Antiapoptotic function of 17AA(+) WT1 (Wilms' tumor gene) isoforms on the intrinsic apoptosis pathway
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DOI：
10.1038/sj.onc.1209455
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发表时间：
2006-07-01
期刊：
影响因子：
8
通讯作者：
Sugiyama, H.
中科院分区：
文献类型：
--
作者：
Ito, K.;Oji, Y.;Sugiyama, H.
WT 1基因在人类原发性白血病和多种实体癌中过表达。WT 1基因在两个位点选择性剪接，产生四种亚型：17 AA（+）KTS（+）、17 AA（+）KTS（-）、17 AA（-）KTS（+）和17 AA（-）KTS（-）。在此，我们发现17 AA（+）WT 1特异性siRNA在三种表达WT 1的白血病细胞系（K562、HL-60和Kasumi-1）中诱导凋亡，但在不表达WT 1的淋巴瘤细胞系（Daudi）中不诱导凋亡。17 AA（+）WT 1特异性siRNA激活内源性凋亡途径中的caspase- 3和caspase- 9，但不激活外源性凋亡途径中的caspase- 8。另一方面，17 AA（-）WT 1特异性siRNA在三种WT 1表达细胞系中不诱导凋亡。凋亡与促凋亡Bax的激活有关，Bax在线粒体上游被激活。17 AA（+）WT 1组成型表达可通过保护线粒体膜损伤抑制足叶乙甙和阿霉素诱导的K562白血病细胞凋亡，17 AA（+）WT 1锌指区是其抗凋亡功能的关键。我们进一步研究了其表达被17 AA（+）WT 1同种型的表达改变的基因，并表明促凋亡巴克的表达被17 AA（+）KTS（-）WT 1同种型的表达降低。综上所述，这些结果表明，17 AA（+）WT 1亚型在线粒体上游的某些点发挥抗凋亡作用的内在凋亡途径。
The WT1 gene is overexpressed in human primary leukemia and a wide variety of solid cancers. The WT1 gene is alternatively spliced at two sites, yielding four isoforms: 17AA(+) KTS(+), 17AA(+) KTS(-), 17AA(-) KTS(+), and 17AA(-) KTS(-). Here, we showed that 17AA(+) WT1-specific siRNA induced apoptosis in three WT1-expressing leukemia cell lines (K562, HL-60, and Kasumi-1), but not in WT1-nonexpressing lymphoma cell line (Daudi). 17AA(+) WT1-specific siRNA activated caspase- 3 and - 9 in the intrinsic apoptosis pathway but not caspase- 8 in the extrinsic one. On the other hand, 17AA(-) WT1-specific siRNA did not induce apoptosis in the three WT1-expressing cell lines. The apoptosis was associated with activation of proapoptotic Bax, which was activated upstream of the mitochondria. Constitutive expression of 17AA(+) WT1 isoforms inhibited apoptosis of K562 leukemia cells induced by apoptosis-inducing agents, etoposide and doxorubicin, through the protection of mitochondrial membrane damages, and DNA-binding zinc-finger region of 17AA(+) WT1 isoform was essential for the antiapoptotic functions. We further studied the gene(s) whose expression was altered by the expression of 17AA(+) WT1 isoforms and showed that the expression of proapoptotic Bak was decreased by the expression of 17AA(+) KTS(-) WT1 isoform. Taken together, these results indicated that 17AA(+) WT1 isoforms played antiapoptotic roles at some points upstream of the mitochondria in the intrinsic apoptosis pathway.