Lazebnik Y A, Takahashi A, Poirier G G, Kaufmann S H, Earnshaw W C
Department of Cell Biology and Anatomy, Johns Hopkins School of Medicine, Baltimore, MD 21205, USA.
J Cell Sci Suppl. 1995;19:41-9. doi: 10.1242/jcs.1995.supplement_19.6.
Apoptotic cell death is characterized by a dramatic morphological transformation during which apparently healthy cells suddenly initiate a comprehensive program of motility changes and degradative activities that culminates in disassembly of the cell into membrane-enclosed vesicles. The mechanism of the cellular changes during this spectacular execution phase of apoptosis is just now yielding to biochemical analysis. In our laboratory, we have applied a novel in vitro system to the study of these events. In this system, nuclei isolated from healthy cells undergo the characteristic changes of apoptosis rapidly and synchronously. Using this system we have identified the first substrates for interleukin-1 beta-converting enzyme (ICE)-like proteinases during apoptotic execution. One of these, the nuclear enzyme poly (ADP-ribose) polymerase is cleaved very early in the apoptotic process. A second class of proteins, the nuclear lamins, is cleaved later in the pathway. Lamin cleavage requires a second ICE-related proteinase, and is essential for the complete dissolution of nuclei into apoptotic bodies. Studies with our cell-free extracts reveal that the various proteinases and nucleases that operate during the execution phase of apoptosis do so largely in independent parallel biochemical pathways. However, all of these pathways require the action of ICE-related proteinases for their initiation.
凋亡性细胞死亡的特征是发生显著的形态学转变，在此过程中，看似健康的细胞突然启动一系列全面的运动变化和降解活动程序，最终导致细胞解体为膜包裹的小泡。在凋亡这一惊人的执行阶段，细胞变化的机制刚刚开始接受生化分析。在我们实验室，我们应用了一种新型体外系统来研究这些事件。在这个系统中，从健康细胞分离出的细胞核会迅速且同步地经历凋亡的特征性变化。利用这个系统，我们在凋亡执行过程中鉴定出了白细胞介素-1β转换酶（ICE）样蛋白酶的首批底物。其中之一，核酶聚（ADP-核糖）聚合酶在凋亡过程的早期就被切割。第二类蛋白质，即核纤层蛋白，在该途径的后期被切割。核纤层蛋白的切割需要第二种ICE相关蛋白酶，并且对于细胞核完全溶解形成凋亡小体至关重要。对我们无细胞提取物的研究表明，在凋亡执行阶段起作用的各种蛋白酶和核酸酶大多在独立的平行生化途径中发挥作用。然而，所有这些途径都需要ICE相关蛋白酶的作用来启动。
