水稻和昆虫细胞自噬期间自噬体发生的细胞学机理

Cytological Mechanism of Autophagosome Biogenesis During Cell Autophagic Apoptosis in Rice and Insect Cell

【目的】从细胞学角度研究细胞自噬过程中膜结构细胞器的变化及其与自噬体发生的关系。【方法】以基因互作引起细胞调亡现象发生的水稻爪粳杂种F1和天然化合物印楝素、喜树碱、苦参碱诱导凋亡的昆虫细胞Sf9为材料,通过透射电子显微镜和荧光显微镜技术观察细胞自噬凋亡期间自噬体的特征。【结果】水稻杂种F1花粉母细胞在不同发育时期存在不同程度的退化,部分细胞内线粒体形态发生显著变化,形成长哑铃型或线管状,最后两端弯曲形成双层膜结构的细胞器;绒毡层细胞均出现内质网膨大,且逐渐包裹周围其它细胞器,如线粒体,形成双层膜结构的自噬体,最终引发细胞的自噬性凋亡。喜树碱和苦参碱诱发凋亡的细胞胞内线粒体形态发生拉长、弯曲,最后闭合形成包裹其它细胞器的双层膜结构自噬体;印楝素和喜树碱诱发凋亡的细胞胞内核通过分页和出芽的方式形成双层膜结构自噬体。【结论】动植物细胞自噬凋亡过程中,内质网、线粒体和细胞核3种膜结构细胞器均是自噬体膜结构的直接来源,然而3种膜结构细胞器参与自噬体形成的程度和方式因物种、细胞种类以及自噬诱发因素的变化而不同。

[Objective] An experiment was carried out to study the change of membrane organelles during cell autophagy and the relationship of membrane organelles and autophagosome biogenesis at cellular level. [ Method] Recent studies have shown that cell apoptosis in the Japonica/Javanica hybrid rice F1 is caused by gene interactions and apoptotic Sf9 cell can be induced by natural chemicals such as azadirachtin, camptothecin, and matrine. In this study, autophagosome biogenesis were observed in the cells of hybrid rice F1 and Sf6 cells treated by chemicals using transmission electron microscope and fluorescence microscopy. [Result] The results showed that pollen mother cells of hybrid rice F1 degenerated partly at different stages during microsporogenesis. The morphology of mitochondria in some cells expanded into dumbbell or pipe-like line shape which eventually developed into a double-membrane organelle. Whereas, in tapetal cells the endoplasmic reticulum swelled and expanded into a double-membrane autophagosomes, enwrapping a portion of cytoplasm and other organelles such as mitochondrias and peroxisomes, suggesting the occurrence of autophagic apoptosis. The mitochondrias in apoptotic cells treated by camptothecin and matrine elongated and curved into dumbbell or pipe-like line shape which eventually developed into double-membrane autophagosomes, enwrapping other organelles. Nuclei in apoptotic cells treated by azadirachtin or camptothecin formed the double-membrane autophagosomes by theways of pagination and sprouting. [Conclusion] In conclusion, the membrane organelles including endoplasmic reticulum, mitochondrias and nuclei were all the direct origin of autophagosome membrane during the autophagic apoptosis in plant and animal cells. However, the degree and manner contributed by the three membrane organelles during the formation of autophagosome were dependent on the species, cell categories and the factors inducing apoptosis.