Salucci S, Burattini S, Falcieri E, Gobbi P
University of Urbino Carlo Bo.
Eur J Histochem. 2015 Sep 15;59(3):2539. doi: 10.4081/ejh.2015.2539.
Apoptosis is an essential biological function required during embryogenesis, tissue homeostasis, organ development and immune system regulation. It is an active cell death pathway involved in a variety of pathological conditions. During this process cytoskeletal proteins appear damaged and undergo an enzymatic disassembling, leading to formation of apoptotic features. This study was designed to examine the three-dimensional chromatin behavior and cytoskeleton involvement, in particular actin re-modeling. HL-60 cells, exposed to hyperthermia, a known apoptotic trigger, were examined by means of a Field Emission in Lens Scanning Electron Microscope (FEISEM). Ultrastructural observations revealed in treated cells the presence of apoptotic patterns after hyperthermia trigger. In particular, three-dimensional apoptotic chromatin rearrangements appeared involving the translocation of filamentous actin from cytoplasm to the nucleus. FEISEM immunogold techniques showed actin labeling and its precise three-dimensional localization in the diffuse chromatin, well separated from the condensed one. The actin presence in dispersed chromatin inside the apoptotic nucleus can be considered an important feature, indispensable to permit the apoptotic machinery evolution.
细胞凋亡是胚胎发育、组织稳态、器官发育和免疫系统调节过程中必需的生物学功能。它是一种涉及多种病理状况的主动细胞死亡途径。在此过程中，细胞骨架蛋白出现损伤并经历酶解，导致凋亡特征的形成。本研究旨在检查三维染色质行为和细胞骨架的参与情况，特别是肌动蛋白重塑。通过场发射透镜扫描电子显微镜（FEISEM）检查暴露于热疗（一种已知的凋亡触发因素）的HL-60细胞。超微结构观察显示，热疗触发后处理过的细胞中存在凋亡模式。特别是，出现了三维凋亡染色质重排，涉及丝状肌动蛋白从细胞质向细胞核的转位。FEISEM免疫金技术显示了肌动蛋白标记及其在弥散染色质中的精确三维定位，与凝聚染色质明显分开。凋亡细胞核内分散染色质中肌动蛋白的存在可被视为一个重要特征，是凋亡机制演变所不可或缺的。
