The Transcriptome of Leishmania major Developmental Stages in Their Natural Sand Fly Vector.
The Transcriptome of Leishmania major Developmental Stages in Their Natural Sand Fly Vector.
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DOI：
10.1128/mbio.00029-17
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发表时间：
2017-04-04
期刊：
影响因子：
6.4
通讯作者：
Sacks DL
中科院分区：
文献类型：
--
作者：
Inbar E;Hughitt VK;Dillon LA;Ghosh K;El-Sayed NM;Sacks DL
白蛉媒介中的利什曼原虫寄生虫的生命周期涉及分化成几种独特的形式，每种形式都被认为代表了对苍蝇中肠中特定微环境的适应。基于转录组测序 (RNA-Seq) 结果，我们描述了对利什曼原虫在天然载体杜博斯奇 (Phlebotomus duboscqi) 中发育时的四个不同阶段的转录组动态的首次高分辨率分析。血液喂养的中肠中从组织无鞭毛体到前循环前鞭毛体的早期转变伴随着最大数量的差异表达基因，包括无长体素的下调，多种细胞表面蛋白、糖和氨基酸转运蛋白的上调，以及与葡萄糖代谢和细胞周期进程相关的基因。伴随原循环前鞭毛体在血粉后分化至内生单胞和后循环阶段的整体变化不太广泛，尽管每种变化都显示出独特的特征。此前尚未研究过的内生单胞菌的转录组揭示了与细胞周期停滞一致的变化以及与饥饿和应激相关的基因上调，包括蛋白质循环的自噬途径。成熟到感染性、后循环阶段伴随着表明对哺乳动物宿主细胞内环境的预适应的变化，表面蛋白和代谢相关基因的无鞭毛体样特征证明了这一点。最后，白蛉源性和培养源性元循环之间的直接比较揭示了两种形式之间令人放心的相似性，体内形式的区别主要在于与营养应激相关的转录本的更强上调。白蛉载体中利什曼原虫寄生虫的生命周期包括它们的生长和发育，作为在肠道不同微环境中发现的形态不同的细胞外前鞭毛体形式。基于RNA-Seq，我们在这里首次对利什曼原虫昆虫在体内周期性发育过程中的阶段进行高分辨率转录组分析，从随血粉摄入的组织无鞭毛体到在哺乳动物宿主中引发感染的感染性、后循环前鞭毛体。最广泛的基因重编程发生在无鞭毛体早期转化为血液喂养的中肠中快速分裂的原循环前鞭毛体的过程中，表面蛋白和代谢的 mRNA 丰度发生重大变化。血餐后适应内单胞菌阶段的特征是细胞周期相关基因的下调以及应激和饥饿相关基因的上调。最后，后循环前鞭毛体的转录组转变为更像无鞭毛体的特征，表明它们预适应了细胞内宿主环境。
The life cycle of the Leishmania parasite in the sand fly vector involves differentiation into several distinctive forms, each thought to represent an adaptation to specific microenvironments in the midgut of the fly. Based on transcriptome sequencing (RNA-Seq) results, we describe the first high-resolution analysis of the transcriptome dynamics of four distinct stages of Leishmania major as they develop in a natural vector, Phlebotomus duboscqi. The early transformation from tissue amastigotes to procyclic promastigotes in the blood-fed midgut was accompanied by the greatest number of differentially expressed genes, including the downregulation of amastins, and upregulation of multiple cell surface proteins, sugar and amino acid transporters, and genes related to glucose metabolism and cell cycle progression. The global changes accompanying post-blood meal differentiation of procyclic promastigotes to the nectomonad and metacyclic stages were less extensive, though each displayed a unique signature. The transcriptome of nectomonads, which has not been studied previously, revealed changes consistent with cell cycle arrest and the upregulation of genes associated with starvation and stress, including autophagic pathways of protein recycling. Maturation to the infective, metacyclic stage was accompanied by changes suggesting preadaptation to the intracellular environment of the mammalian host, demonstrated by the amastigote-like profiles of surface proteins and metabolism-related genes. Finally, a direct comparison between sand fly-derived and culture-derived metacyclics revealed a reassuring similarity between the two forms, with the in vivo forms distinguished mainly by a stronger upregulation of transcripts associated with nutrient stress. The life cycle of Leishmania parasites in the sand fly vector includes their growth and development as morphologically distinct forms of extracellular promastigotes found within the different microenvironments of the gut. Based on RNA-Seq, we provide here the first high-resolution, transcriptomic analysis of Leishmania insect stages during their cyclical development in vivo, from tissue amastigotes ingested with the blood meal to infective, metacyclic promastigotes that initiate infection in the mammalian host. The most extensive genetic reprogramming occurred during the early transformation of amastigotes to rapidly dividing procyclic promastigotes in the blood-fed midgut, with major changes in the abundance of mRNAs for surface proteins and metabolism. The post-blood meal-adapted nectomonad stage was characterized by the downregulation of cell cycle-related genes and the upregulation of stress- and starvation-related genes. Finally, the transcriptome of metacyclic promastigotes shifted to a more amastigote-like profile, suggesting their preadaptation to the intracellular host environment.