Ohsawa S, Hamada S, Yoshida H, Miura M
Department of Genetics, Graduate School of Pharmaceutical Sciences, University of Tokyo and CREST, JST, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Cell Death Differ. 2008 Sep;15(9):1429-39. doi: 10.1038/cdd.2008.71. Epub 2008 May 16.
Programmed cell death or apoptosis is required for the patterning and development of multicellular organisms. However, apoptosis is a difficult process to measure because the dead cells are rapidly degraded by their neighbors within a few hours. The post-caspase activation events that determine whether a cell will undergo apoptosis remain elusive. Here we report that apoptosis-specific nuclear events that occur before DNA fragmentation can be distinguished by monitoring the histone H1 status. In both mammals and Drosophila, dying cells failed to be immunolabeled with an anti-H1 monoclonal antibody, AE-4. Real-time imaging of caspase activation and H1 dynamics in mammalian neural cells revealed that H1 changed its location in the nucleus after caspase activation. In addition, the timing of this re-localization was largely dependent on the apoptotic stimulus used. From the staining patterns of AE-4 and anti-active caspase-3 antibodies, cells undergoing the transition from caspase activation to the apoptotic H1 change could be identified as H1-positive caspase-activated cells, providing a novel criterion for early apoptosis and making it possible to characterize caspase-activated cells in tissues. On the basis of these staining patterns, we found that many olfactory sensory neurons in the developing mouse olfactory epithelium showed sustained caspase activity without the H1 change, suggesting a unique caspase function in these neurons.
程序性细胞死亡或凋亡是多细胞生物体模式形成和发育所必需的。然而，凋亡是一个难以测量的过程，因为死亡细胞会在数小时内被其相邻细胞迅速降解。决定细胞是否会发生凋亡的半胱天冬酶激活后事件仍然不清楚。在此，我们报告通过监测组蛋白H1状态可以区分DNA片段化之前发生的凋亡特异性核事件。在哺乳动物和果蝇中，濒死细胞均不能被抗H1单克隆抗体AE-4免疫标记。对哺乳动物神经细胞中半胱天冬酶激活和H1动态的实时成像显示，半胱天冬酶激活后H1在细胞核内的位置发生了变化。此外，这种重新定位的时间很大程度上取决于所使用的凋亡刺激。根据AE-4和抗活性半胱天冬酶-3抗体的染色模式，从半胱天冬酶激活过渡到凋亡性H1变化的细胞可被鉴定为H1阳性半胱天冬酶激活细胞，这为早期凋亡提供了一个新的标准，并使得在组织中鉴定半胱天冬酶激活细胞成为可能。基于这些染色模式，我们发现发育中的小鼠嗅觉上皮中的许多嗅觉感觉神经元表现出持续的半胱天冬酶活性而没有H1变化，这表明这些神经元中存在独特的半胱天冬酶功能。
