Casiano C A, Ochs R L, Tan E M
WM Keck Autoimmune Disease Center, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
Cell Death Differ. 1998 Feb;5(2):183-90. doi: 10.1038/sj.cdd.4400336.
A central mechanism in apoptosis is the activation of proteases of the caspase (cysteine aspartases) family. Protease activation has also been implicated in necrosis, but its role in this cell death process and the identity of the proteases involved and their substrates, are unknown. Using human autoantibodies to well characterized cellular proteins as detecting probes in immunoblotting, we observed that a defined and somewhat similar set of nuclear proteins, including poly (ADP-ribose) polymerase (PARP) and DNA topoisomerase I (Topo I), were selectively cleaved during both apoptosis and necrosis of cultured cells induced by various stimuli. The resulting cleavage products were distinctively different in the two cell death pathways. In contrast to apoptosis, the cleavages of PARP and Topo I during necrosis were not blocked by the caspase inhibitor benzyloxycarbonyl-Val-Ala-Asp-fluoromethyl ketone (zVAD-fmk). These findings suggest that different proteases act in apoptosis and necrosis, and that although both cell death processes result in selective cleavage of almost identical cellular proteins, they can be distinguished immunochemically on the basis of their cleavage products.
细胞凋亡的一个核心机制是半胱天冬酶（半胱氨酸天冬氨酸蛋白酶）家族蛋白酶的激活。蛋白酶激活也与坏死有关，但其在这种细胞死亡过程中的作用以及所涉及的蛋白酶及其底物的身份尚不清楚。我们使用针对特征明确的细胞蛋白的人类自身抗体作为免疫印迹中的检测探针，观察到在由各种刺激诱导的培养细胞凋亡和坏死过程中，一组特定且有些相似的核蛋白，包括聚（ADP - 核糖）聚合酶（PARP）和DNA拓扑异构酶I（Topo I），被选择性切割。在两种细胞死亡途径中产生的切割产物明显不同。与细胞凋亡相反，坏死过程中PARP和Topo I的切割不受半胱天冬酶抑制剂苄氧羰基 - 缬氨酸 - 丙氨酸 - 天冬氨酸 - 氟甲基酮（zVAD - fmk）的阻断。这些发现表明，不同的蛋白酶在细胞凋亡和坏死中起作用，并且尽管两种细胞死亡过程都会导致几乎相同的细胞蛋白的选择性切割，但它们可以根据其切割产物在免疫化学上加以区分。
