Zhu Pengcheng, Martinvalet Denis, Chowdhury Dipanjan, Zhang Dong, Schlesinger Ann, Lieberman Judy
Immune Disease Institute and Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA.
Blood. 2009 Aug 6;114(6):1205-16. doi: 10.1182/blood-2008-12-195768. Epub 2009 Jun 8.
Granzyme A (GzmA) in killer cells induces caspase-independent programmed cell death. In this study, we show that GzmA cleaves the DNA damage sensor poly(adenosine 5'-diphosphate-ribose) polymerase-1 (PARP-1) after Lys(498) in its automodification domain, separating the DNA binding domain from the catalytic domain, which interferes with repair of GzmA-induced DNA damage and enhances susceptibility to GzmA-mediated death. Overexpressing K498A PARP-1 reduces GzmA-mediated death and drives dying cells to necrosis rather than apoptosis. Conversely, inhibiting or genetically disrupting PARP-1 enhances cell vulnerability. The N-terminal GzmA cleavage fragment of PARP-1 acts as a PARP-1 dominant negative, binding to DNA and blocking DNA repair. Disrupting PARP-1, which is also a caspase target, is therefore required for efficient apoptosis by both caspase-independent and caspase-dependent pathways.
杀伤细胞中的颗粒酶A（GzmA）可诱导不依赖半胱天冬酶的程序性细胞死亡。在本研究中，我们发现GzmA在其自身修饰结构域中的赖氨酸（Lys）498之后切割DNA损伤传感器聚（腺苷5'-二磷酸核糖）聚合酶-1（PARP-1），将DNA结合结构域与催化结构域分离，这会干扰GzmA诱导的DNA损伤修复并增强对GzmA介导的死亡的易感性。过表达K498A PARP-1可减少GzmA介导的死亡，并使垂死细胞走向坏死而非凋亡。相反，抑制或基因破坏PARP-1会增强细胞的脆弱性。PARP-1的N端GzmA切割片段作为PARP-1显性负性蛋白，与DNA结合并阻断DNA修复。因此，破坏PARP-1（它也是半胱天冬酶的作用靶点）对于通过不依赖半胱天冬酶和依赖半胱天冬酶的途径实现有效凋亡都是必需的。
