Biogenesis of the trypanosome endo-exocytotic organelle is cytoskeleton mediated.
Biogenesis of the trypanosome endo-exocytotic organelle is cytoskeleton mediated.
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DOI：
10.1371/journal.pbio.0060105
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发表时间：
2008-05-06
期刊：
影响因子：
9.8
通讯作者：
Robinson DR
中科院分区：
文献类型：
--
作者：
Bonhivers M;Nowacki S;Landrein N;Robinson DR
布鲁氏锥虫是一种原生动物寄生虫，被用作研究基因表达、蛋白质转运和细胞骨架生物发生等生物现象的模式生物。在布氏体中，胞吞作用和胞吐作用完全通过被称为鞭毛囊（FP）的隔离细胞器发生，鞭毛囊是细胞膜的内陷。口袋是特定受体的唯一位置，因此保持它们无法进入哺乳动物宿主先天免疫系统的成分。FP还负责对针对或从细胞膜中回收的保护性寄生虫糖蛋白进行分选，并从细胞表面去除宿主抗体。在这里，我们描述了鞭毛口袋细胞骨架蛋白BILBO1的第一个特征。BILBO1的功能是形成FP生成的细胞骨架框架，也是FP生物发生和细胞存活所必需的。值得注意的是，RNA干扰（RNAi）介导的昆虫原环型寄生虫中BILBO1的消融可阻止FP的生物生成，并诱导囊泡积聚、高尔基体肿胀、新鞭毛的异常重新定位和细胞死亡。培养的血流型寄生虫在受到BILBO1 RNAi时也不能存活。这些结果为细胞骨架介导的FP生物发生提供了第一个分子证据。锥虫是一种普遍存在的单细胞寄生虫，可感染人类、动物、昆虫和植物。非洲、亚洲和一些南美锥虫已经进化出了改变其表面外壳蛋白质的惊人能力，这是它们生存的基本策略。表面涂层蛋白通过一种被称为鞭毛囊的内吞和胞外细胞器被循环利用并靶向到寄生虫的表面，鞭毛囊被隔离在锥虫细胞的细胞质中。鞭毛袋也被用来去除附着在寄生虫表面的宿主来源的抗体，使这个细胞器对寄生虫逃避宿主免疫系统至关重要。我们描述了一种新的蛋白质“BILBO1”，它是从非洲锥虫布鲁氏锥虫的昆虫形寄生虫中鉴定出来的。我们发现BILBO1是环状或马蹄形细胞骨架结构的一部分，该结构位于鞭毛口袋称为领子的区域。当用可诱导的RNA干扰敲除BILBO1转录本时，锥虫细胞在有丝分裂后的细胞周期阶段被阻滞。诱导细胞失去了正常的鞭毛与细胞体的附着，不能调节内吞和胞吐，最重要的是，不能构建新的鞭毛袋。这些结果为鞭毛囊生物发生是由细胞骨架介导的观点提供了分子证据。寄生虫蛋白BILBO1的RNAi阻止了布鲁氏锥虫内吞和胞外细胞器的生物发生，杀死了寄生虫，并揭示了这种病原体如何组织和使用其独特的细胞器之一的新见解。
Trypanosoma brucei is a protozoan parasite that is used as a model organism to study such biological phenomena as gene expression, protein trafficking, and cytoskeletal biogenesis. In T. brucei, endocytosis and exocytosis occur exclusively through a sequestered organelle called the flagellar pocket (FP), an invagination of the pellicular membrane. The pocket is the sole site for specific receptors thus maintaining them inaccessible to components of the innate immune system of the mammalian host. The FP is also responsible for the sorting of protective parasite glycoproteins targeted to, or recycling from, the pellicular membrane, and for the removal of host antibodies from the cell surface. Here, we describe the first characterisation of a flagellar pocket cytoskeletal protein, BILBO1. BILBO1 functions to form a cytoskeleton framework upon which the FP is made and which is also required and essential for FP biogenesis and cell survival. Remarkably, RNA interference (RNAi)-mediated ablation of BILBO1 in insect procyclic-form parasites prevents FP biogenesis and induces vesicle accumulation, Golgi swelling, the aberrant repositioning of the new flagellum, and cell death. Cultured bloodstream-form parasites are also nonviable when subjected to BILBO1 RNAi. These results provide the first molecular evidence for cytoskeletally mediated FP biogenesis. Trypanosomes are ubiquitous unicellular parasites that infect humans, animals, insects, and plants. African, Asian, and some South American trypanosomes have evolved the amazing ability to change their surface coat proteins, an essential strategy for their survival. The surface coat proteins are recycled and targeted to the surface of the parasite via an endocytic and exocytotic organelle called the flagellar pocket, which is sequestered in the trypanosome cell's cytoplasm. The flagellar pocket is also used to remove host-derived antibodies that are bound to the surface of the parasite, making this organelle critical for the parasite's evasion of the host immune system. We describe a novel protein, “BILBO1,” which was identified from the insect-form parasite of the African trypanosome Trypanosoma brucei. We show that BILBO1 is part of a ring or horseshoe-like cytoskeletal structure that is located in a region of the flagellar pocket called the collar. When BILBO1 transcripts were knocked down with inducible RNA interference, trypanosome cells became arrested in a post-mitotic cell-cycle stage. Induced cells lost the normal flagellum-to-cell-body attachment, were unable to regulate endocytosis and exocytosis, and most importantly, were unable to construct a new flagellar pocket. These results provide molecular evidence for the idea that flagellar pocket biogenesis is cytoskeletally mediated. RNAi of the parasite protein BILBO1 prevents the biogenesis of the endocytic and exocytotic organelle in Trypanosoma brucei, kills the parasite, and reveals novel insights into how this pathogen organizes and uses one of its distinctive organelles.
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影响因子：
64.5
作者：
Engstler, Markus;Pfohl, Thomas;Overath, Peter
通讯作者：
Overath, Peter
影响因子：
1.5
作者：
Ackers, JP;Dhir, V;Field, MC
通讯作者：
Field, MC
影响因子：
1.5
作者：
Bringaud, F;Robinson, DR;Baltz, T
通讯作者：
Baltz, T
影响因子：
2.1
作者：
Hall, BS;Pal, A;Field, MC
通讯作者：
Field, MC
DOI：
10.1083/jcb.200504107
发表时间：
2005-10-10
期刊：
The Journal of cell biology
影响因子：
--
作者：
Bahe S;Stierhof YD;Wilkinson CJ;Leiss F;Nigg EA
通讯作者：
Nigg EA