Downregulation of ANP32B, a novel substrate of caspase-3, enhances caspase-3 activation and apoptosis induction in myeloid leukemic cells
Downregulation of ANP32B, a novel substrate of caspase-3, enhances caspase-3 activation and apoptosis induction in myeloid leukemic cells
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Caspase-3 的新型底物 ANP32B 的下调可增强髓系白血病细胞中 caspase-3 的激活和凋亡诱导
DOI：
10.1093/carcin/bgp320
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发表时间：
2010-03-01
期刊：
影响因子：
4.7
通讯作者：
Chen, Guo-Qiang
中科院分区：
文献类型：
--
作者：
Shen, Shao-Ming;Yu, Yun;Chen, Guo-Qiang
酸性富亮氨酸核磷蛋白32（ANP 32）B已被报道通过充当组蛋白伴侣来调节基因表达或通过充当HuR配体来调节信使RNA运输。然而，其确切的细胞功能知之甚少。通过利用蛋白质组学为基础的方法，在这项工作中，我们确定，人类ANP 32 B蛋白被切割在细胞凋亡诱导NSC 606985，一种新的喜树碱类似物。进一步的研究表明，各种细胞凋亡诱导剂导致多种细胞系中全长ANP 32 B的减少，伴随着类似于17 kDa片段的增加。ANP 32 B的蛋白水解裂解被特异性半胱天冬酶-3抑制剂Z-DEVD-factory抑制，并且在NSC 606985诱导的半胱天冬酶-3缺陷型MCF-7细胞死亡中看不到。caspase-3的体外切割实验和突变实验表明，ANP 32 B是caspase-3的直接底物，它主要在Asp-163之后的Ala-Glu-Val-Asp序列上被切割。此外，通过特异性小干扰RNA降低内源性ANP 32 B的表达增强了NSC 606985和依托泊苷对胱天蛋白酶-3的激活和凋亡诱导。这些结果表明，ANP 32 B是caspase-3的一种新底物，并作为细胞凋亡的负调节剂，其机制仍有待探讨。
The acidic leucine-rich nuclear phosphoprotein 32 (ANP32)B has been reported to regulate gene expression by acting as a histone chaperone or modulate messenger RNA trafficking by serving as a HuR ligand. However, its exact cellular functions are poorly understood. By utilizing a proteomics-based approach, in this work, we identify that the human ANP32B protein is cleaved during apoptosis induction by NSC606985, a novel camptothecin analog. Further investigation shows that various apoptosis inducers cause a decrease of full-length ANP32B in multiple cell lines with a concomitant increase of an similar to 17 kDa fragment. The proteolytic cleavage of ANP32B is inhibited by a specific caspase-3 inhibitor Z-DEVD-fmk, and it cannot be seen in NSC606985-induced death of caspase-3-deficient MCF-7 cells. In vitro caspase cleavage assay and mutagenesis experiment reveal that ANP32B is a direct substrate of caspase-3 and it is primarily cleaved at the sequence of Ala-Glu-Val-Asp, after Asp-163. Additionally, the reduced expression of endogenous ANP32B by specific small interfering RNA enhances caspase-3 activation and apoptosis induction by NSC606985 and etoposide. These results suggest that ANP32B is a novel substrate for caspase-3 and acts as a negative regulator for apoptosis, the mechanism of which remains to be explored.