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摘要 : 脂质双层会发生融合或分裂,分别产生更大或更小的细胞器,但它们是通过一个半融合的中间体还是一个内壁有蛋白的小孔来做这件事情的仍然存在争议。

 脂质双层会发生融合或分裂,分别产生更大或更小的细胞器,但它们是通过一个半融合的中间体还是一个内壁有蛋白的小孔来做这件事情的仍然存在争议。Ling-Gang Wu及同事利用超高分辨率显微镜在融合和分裂过程中对活细胞中的半融合中间体进行了直接观察。他们的数据表明,钙和动力蛋白在融合和分裂之间控制两个方向的可逆转变。


Hemi-fused structure mediates and controls fusion and fission in live cells


Membrane fusion and fission are vital for eukaryotic life1, 2, 3, 4, 5. For three decades, it has been proposed that fusion is mediated by fusion between the proximal leaflets of two bilayers (hemi-fusion) to produce a hemi-fused structure, followed by fusion between the distal leaflets, wheras fission is via hemi-fission, which also produces a hemi-fused structure, followed by full fission1, 4, 6,7, 8, 9, 10. This hypothesis remained unsupported owing to the lack of observation of hemi-fusion or hemi-fission in live cells. A competing fusion hypothesis involving protein-lined pore formation has also been proposed2, 11, 12, 13, 14, 15. Here we report the observation of a hemi-fused Ω-shaped structure in live neuroendocrine chromaffin cells and pancreatic β-cells, visualized using confocal and super-resolution stimulated emission depletion microscopy. This structure is generated from fusion pore opening or closure (fission) at the plasma membrane. Unexpectedly, the transition to full fusion or fission is determined by competition between fusion and calcium/dynamin-dependent fission mechanisms, and is notably slow (seconds to tens of seconds) in a substantial fraction of the events. These results provide key missing evidence in support of the hemi-fusion and hemi-fission hypothesis in live cells, and reveal the hemi-fused intermediate as a key structure controlling fusion and fission, as fusion and fission mechanisms compete to determine the transition to fusion or fission.

来源: Nature 浏览次数:0


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