Cell cycle-regulated, microtubule-independent organelle division in Cyanidioschyzon merolae
Cell cycle-regulated, microtubule-independent organelle division in Cyanidioschyzon merolae
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DOI：
10.1091/mbc.e05-01-0068
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发表时间：
2005-05-01
影响因子：
3.3
通讯作者：
Kuroiwa, T
中科院分区：
文献类型：
--
作者：
Nishida, K;Yagisawa, F;Kuroiwa, T
线粒体和叶绿体分裂控制细胞器的数量和形态，但细胞如何调节细胞器分裂仍有待澄清。在这里，我们表明，线粒体和叶绿体分裂的每一步都与Cyanidioschyzon merolae的细胞周期密切相关。电子显微镜显示纺锤体极体和线粒体之间的直接关联，这表明线粒体分布与有丝分裂物理耦合。在微管稳定条件下分离相互连接的细胞器。免疫印迹分析表明，细胞器分裂所需的蛋白质水平增加之前，微管变化后细胞分裂，表明细胞器分裂的蛋白质表达的调节是不同的胞质分裂。在线粒体分裂部位，发动蛋白粘附在其中一个分裂的线粒体上，并在空间上与从另一个线粒体延伸出来的微管尖端相关联。抑制微管组织，蛋白酶体活性或DNA合成，分别诱导逮捕细胞分裂，但萎缩的线粒体，分裂和分离的线粒体，或与不完整的线粒体分裂限制在最后的断绝，和重复的叶绿体分裂。结果表明，线粒体的形态和分离，而不是分裂依赖于微管，并暗示这两个细胞器的分裂过程中受到不同的检查点。
Mitochondrial and chloroplast division controls the number and morphology of organelles, but how cells regulate organelle division remains to be clarified. Here, we show that each step of mitochondrial and chloroplast division is closely associated with the cell cycle in Cyanidioschyzon merolae. Electron microscopy revealed direct associations between the spindle pole bodies and mitochondria, suggesting that mitochondrial distribution is physically coupled with mitosis. Interconnected organelles were fractionated under microtubule-stabilizing condition. Immunoblotting analysis revealed that the protein levels required for organelle division increased before microtubule changes upon cell division, indicating that regulation of protein expression for organelle division is distinct from that of cytokinesis. At the mitochondrial division site, dynamin stuck to one of the divided mitochondria and was spatially associated with the tip of a microtubule stretching from the other one. Inhibition of microtubule organization, proteasome activity or DNA synthesis, respectively, induced arrested cells with divided but shrunk mitochondria, with divided and segregated mitochondria, or with incomplete mitochondrial division restrained at the final severance, and repetitive chloroplast division. The results indicated that mitochondrial morphology and segregation but not division depend on microtubules and implied that the division processes of the two organelles are regulated at distinct checkpoints.