Zakeri Z F, Quaglino D, Latham T, Lockshin R A
Department of Biology, Queens College, CUNY, Flushing 11367.
FASEB J. 1993 Mar;7(5):470-8. doi: 10.1096/fasebj.7.5.8462789.
DNA fragmentation was evaluated in three instances of programmed cell death, interdigital cell death in embryonic mouse limbs, and metamorphic death of both the labial glands and intersegmental muscle in the tobacco hornworm Manduca sexta. In the mouse, we evaluated both developmental cell death and expanded-range cell death induced by retinoic acid. The status of DNA was examined in several ways. Nuclei were examined by electron microscopy and Feulgen staining. Quantitative assessment of total DNA content in Feulgen-stained degenerating nuclei was made for the gland. In the labial gland, DNA content does not drop during the early phases of cell death; nor is an endonucleolytic ladder seen when DNA was examined by ethidium bromide staining or prelabeling with [3H]thymidine. Only by using end labeling of DNA could we detect DNA fragmentation at a very late stage in cell death, day 4 of the collapse of the gland. In contrast, WEHI 7.1 lymphoma cells display an early and extensive ladder after treatment with glucocorticoids. In mouse limb, for which cell death follows a more classic apoptotic morphology, a ladder is likewise not seen. We conclude that activation of an endonuclease is neither a trigger nor a necessary or defining component of the early phases of developmental programmed cell death, and that reported failure by others to find such a ladder may depend on limitations in the system that is under investigation.
在三种程序性细胞死亡的情况下评估了DNA片段化，即胚胎小鼠肢体的指间细胞死亡，以及烟草天蛾曼陀罗唇腺和节间肌肉的变态死亡。在小鼠中，我们评估了发育性细胞死亡和视黄酸诱导的扩展范围细胞死亡。通过多种方式检查了DNA的状态。通过电子显微镜和福尔根染色检查细胞核。对福尔根染色的退化细胞核中的总DNA含量进行了定量评估。在唇腺中，细胞死亡早期DNA含量没有下降；用溴化乙锭染色或用[3H]胸苷预标记检查DNA时，也没有看到核酸内切酶梯带。只有通过DNA末端标记，我们才能在细胞死亡的很晚阶段，即腺体塌陷的第4天检测到DNA片段化。相比之下，WEHI 7.1淋巴瘤细胞在用糖皮质激素处理后显示出早期且广泛的梯带。在小鼠肢体中，细胞死亡遵循更典型的凋亡形态，同样没有看到梯带。我们得出结论，核酸内切酶的激活既不是发育性程序性细胞死亡早期阶段的触发因素，也不是其必要或决定性组成部分，其他人报告未能找到这样的梯带可能取决于所研究系统的局限性。
