Coordinated Changes in Gene Expression Throughout Encystation of Giardia intestinalis
Coordinated Changes in Gene Expression Throughout Encystation of Giardia intestinalis
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DOI：
10.1371/journal.pntd.0004571
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发表时间：
2016-03-01
影响因子：
3.8
通讯作者：
Svard, Staffan G.
中科院分区：
文献类型：
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作者：
Einarsson, Elin;Troell, Karin;Svard, Staffan G.
肠道原生动物贾第虫通过成囊分化为感染性囊肿是其传播和存活的关键。迄今为止，大多数研究都集中在早期事件上，而对晚期感染的定义不明确。为了进一步研究囊化，重点关注后期事件，我们开发了一种新的囊化方案，与标准方法相比，该方案产生的成熟囊肿产量更高。随后，利用RNA测序（RNA-seq）研究了从滋养体到包囊整个分化过程中转录组的变化。在整个转录组和假定的调节因子水平上，观察到上调和下调基因的高水平周期性。这表明分化的轨迹是通过发育相关的基因调控活动来协调的。我们的研究确定了13个核心基因，这些基因在初始化过程中持续上调。其中，两种构成了以前未表征的蛋白质，我们能够将其定位为一种新型的囊化特异性囊泡。有趣的是，最大的转录变化发生在胞体的后期，大多数高度上调的基因编码假设的蛋白质。其中一些是表位标记和定位，以进一步表征这些以前未知的遗传成分的内积和可能的外积。最后，我们还检测到变异特异性表面蛋白（VSPs）在环化后期的转换。这与核分裂和DNA复制同时发生，表明这两个过程之间存在潜在的联系。
Differentiation into infectious cysts through the process of encystation is crucial for transmission and survival of the intestinal protozoan parasite Giardia intestinalis. Hitherto the majority of studies have focused on the early events, leaving late encystation poorly defined. In order to further study encystation, focusing on the later events, we developed a new encystation protocol that generates a higher yield of mature cysts compared to standard methods. Transcriptome changes during the entire differentiation from trophozoites to cysts were thereafter studied using RNA sequencing (RNA-seq). A high level of periodicity was observed for up-and down-regulated genes, both at the level of the entire transcriptome and putative regulators. This suggests the trajectory of differentiation to be coordinated through developmentally linked gene regulatory activities. Our study identifies a core of 13 genes that are consistently up-regulated during initial encystation. Of these, two constitute previously uncharacterized proteins that we were able to localize to a new type of encystation-specific vesicles. Interestingly, the largest transcriptional changes were seen in the late phase of encystation with the majority of the highly up-regulated genes encoding hypothetical proteins. Several of these were epitope-tagged and localized to further characterize these previously unknown genetic components of encystation and possibly excystation. Finally, we also detected a switch of variant specific surface proteins (VSPs) in the late phase of encystation. This occurred at the same time as nuclear division and DNA replication, suggesting a potential link between the processes.