Replication of the ERES:Golgi junction in bloodstream-form African trypanosomes
Replication of the ERES:Golgi junction in bloodstream-form African trypanosomes
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DOI：
10.1111/j.1365-2958.2011.07900.x
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发表时间：
2011-12-01
影响因子：
3.6
通讯作者：
Bangs, James D.
中科院分区：
文献类型：
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作者：
Bangs, James D.
利用内质网出口部位、高尔基体和胆叶结构的标记标记，研究了血流状非洲锥虫内质网出口部位/高尔基连接(EGJ)的生物发生。典型的模式是在G1期(1个动泡体/1个核，1K1N)到S期(2K1N)有两个EGJ，在有丝分裂后细胞(2K2N)复制到四个EGJ，每个子代分离两个EGJ。细胞比例越小，所有阶段的EGJ拷贝数都会增加，阻止细胞周期进程会导致更高的拷贝数。EGJ与鞭毛附着区(FAZ)紧密排列，表明FAZ相关ER(FAZ：ER)上的成核。每个细胞中只有最后面的EGJ靠近双叶，双叶位于FAZ细丝的底部，靠近鞭毛袋的口。这些结果表明，EGJ在血流锥虫体内的复制与细胞周期没有紧密耦合。此外，EGJ的分离不一定是由双叶细胞介导的，而是EGJ在FAZ上的组装：ER与鞭毛细胞骨架偶联，显然确保了细胞质分裂过程中保真的分离。这些发现与原环状锥虫明显不同，并提出了突出EGJ生物发生中这些阶段特异性差异的模型。
The biogenesis of the ER Exit Site/Golgi Junction (EGJ) in bloodstream-form African trypanosomes is investigated using tagged markers for ER Exit Sites, the Golgi and the bilobe structure. The typical pattern is two EGJ in G1 phase (1 kinetoplast/1 nucleus, 1K1N) through S-phase (2K1N), duplication to four EGJ in post-mitotic cells (2K2N) and segregation of two EGJ to each daughter. Lesser cell percentages have elevated EGJ copy numbers in all stages, and blocking cell cycle progression results in even higher copy numbers. EGJs are closely aligned with the flagellar attachment zone (FAZ) indicating nucleation on the FAZ-associated ER (FAZ:ER). Only the most posterior EGJ in each cell is in proximity to the bilobe, which is located at the base of the FAZ filament near the mouth of the flagellar pocket. These results indicate that EGJ replication in bloodstream trypanosomes is not tightly coupled to the cell cycle. Furthermore, segregation of EGJ is not obligately mediated by the bilobe, rather assembly of the EGJ on the FAZ:ER, which is coupled to the flagellar cytoskeleton, apparently ensures segregation with fidelity during cytokinesis. These findings differ markedly from procyclic-form trypanosomes, and models highlighting these stage-specific differences in EGJ biogenesis are proposed.