[Apoptosis of HL-60 cells induced by Harringtonine: membrane blebs, nucleus blebs and chromatin condensation]

Abstract

Using Video Enhancement Contrast (VEC) microscopy, we recorded the morphological changes of same HL-60 cell in the processes of apoptosis induced by harringtonine. Our results show that all of apoptotic cells need several nucleus blebs before their chromatin condensation. Every nucleus bleb is induced by a relative membrane bleb. The number of membrane blebs is much higher than that of nucleus blebs, so there are only some of membrane blebs which can induce nucleus blebs. It suggested that membrane and nucleus blebs probably are related to apoptotic chromatin condensation. After HL-60 cells pretreated with cytochalasin B(CB), apoptotic chromatin condensation delayed eight hours, but no membrane bleb, nucleus bleb and apoptotic body formed eventually. So membrane and nucleus blebs during apoptosis are related to microfilament re-organization and can accelerate apoptotic chromatin condensation, but are unnecessary for apoptotic chromatin condensation. All this suggested that nuclear changes and cytoplasmic changes during HL-60 cell apoptosis are independent.