Bonanno E, Ruzittu M, Carlà E C, Montinari M R, Pagliara P, Dini L
Dept. of Biology, University of Lecce.
Eur J Histochem. 2000;44(3):237-46.
U937 cells induced to apoptosis, progressively and dramatically modified their cell shape by intense blebbing formation, leading to the production of apoptotic bodies. The blebs evolved with time; milder forms of blebbing involving only a region or just the cortical part of the cytoplasm were observed within the first hour of incubation with puromycin; blebbing involving the whole cell body with very deep constrictions is the most frequent event observed during late times of incubation. The ultrastructural analysis of apoptotic cells revealed characteristic features of nuclear fragmentation (budding and cleavage mode) and cytoplasmatic modifications. The cytoplasm of blebs does not contain organelles, such as ribosomes or mitochondria. Scarce presence of endoplasmic reticulum can be observed at the site of bleb detachment. However, blebbing is a dispensable event as evaluated by using inhibitor of actin polymerization. In the present study, the progressive modifications of the nucleus, mitochondria, nuclear fragmentation, cytoplasmic blebs formation and production of apoptotic bodies in U937 monocytic cells induced to apoptosis by puromycin (an inhibitor of protein synthesis) were simultaneously analyzed.
U937细胞被诱导凋亡时，会通过强烈的气泡形成逐渐且显著地改变其细胞形状，导致凋亡小体的产生。气泡随时间演变；在与嘌呤霉素孵育的第一小时内，观察到仅涉及细胞质区域或仅皮质部分的较温和气泡形成形式；在孵育后期，最常观察到涉及整个细胞体且有非常深缢缩的气泡形成。对凋亡细胞的超微结构分析揭示了核碎片化（出芽和裂解模式）和细胞质修饰的特征。气泡的细胞质中不包含细胞器，如核糖体或线粒体。在气泡脱离部位可观察到少量内质网。然而，通过使用肌动蛋白聚合抑制剂评估，气泡形成是一个非必需事件。在本研究中，同时分析了嘌呤霉素（一种蛋白质合成抑制剂）诱导U937单核细胞凋亡过程中细胞核、线粒体的渐进性修饰、核碎片化、细胞质气泡形成和凋亡小体的产生。
