Mechanism of Infectivity Acquisition in African Trypanosomes

描述（由申请人提供）：揭示人类病原体的生物学是理解发病机制和鉴定宿主生存所必需的基因的基础。这种应用的重点是原生动物寄生虫布氏锥虫，它在撒哈拉以南非洲的人类和动物中引起毁灭性疾病。没有疫苗，治疗药物有严重的副作用和降低疗效。T.布鲁氏菌在哺乳动物宿主和吸血采采蝇载体（双翅目：舌蝇科）之间经历复杂的生命周期，其中涉及细胞形态、代谢、信号通路和基因表达的变化。因此，这些寄生虫已经进化出适应性，允许它们在采采蝇的肠道和唾液腺以及哺乳动物宿主的血流中生存。采采蝇以受感染的宿主为食后，会呈现出细长、中间和粗短的血流形态。在苍蝇中肠短粗的形式分化成非传染性的原循环形式。重新获得传染性是通过一个复杂的发育程序来实现的，该程序在采采蝇唾液腺中达到高潮，产生传染性代谢循环。虽然锥虫在苍蝇中发育的复杂性已经被认识了世纪，但分子机制仍然是神秘的，部分原因是采采蝇带来的实验挑战。我们发现T.培养的非感染性前环形式的布氏RNA结合蛋白RBP6启动分化为采采蝇中发现的发育阶段，并以产生表达变体表面糖蛋白（VSG）外壳的感染性后环体而达到高潮。我们的第一个目标是描述RBP6的作用机制。由于RBP6似乎是触发级联事件的“主调节器”，因此鉴定RBP6的主要mRNA靶将是至关重要的。这将提供关键信息的基因产物参与分化的早期阶段，并制定一个可检验的假设发生在从procyclic到epimastigotes形式的过渡的细胞适应。我们的第二个目标将是提供一个转录组和蛋白质组图谱的epimastigotes和metacyclics和解码的metacyclogenesis的生物学。最后，发现新的基因，除了VSG，所需的元循环分化将是一个重大突破，对破译的过程中获得的感染性是如何带来的。综上所述，我们的研究计划提供了独特的机会，阐明从原环到亚环的分化程序，并揭示了一个重要的RNA结合蛋白的作用模式。

DESCRIPTION (provided by applicant): Unraveling the biology of human pathogens is fundamental toward understanding mechanisms of pathogenesis and identifying genes essential for survival in the host. This application focuses on the protozoan parasite Trypanosoma brucei, which causes devastating diseases in humans and animals in sub-Saharan Africa. There are no vaccines, and therapeutic drugs have serious side effects and decreasing efficacy. T. brucei undergoes a complex life cycle between the mammalian host and the blood-feeding tsetse fly vector (Diptera: Glossinidae), which among others involves changes in cell morphology, metabolism, signaling pathways and gene expression. Consequently, these parasites have evolved adaptations to allow for their survival in both the gut and salivary glands of the tsetse fly, as well as in the bloodstream of their mammalian host. Upon feeding on an infected host, the tsetse fly takes up slender, intermediate and stumpy bloodstream forms. In the fly midgut stumpy forms differentiate into non-infectious procyclic forms. Reacquisition of infectivity is achieved through a complex developmental program that culminates in the tsetse salivary glands with the generation of infectious metacyclics. Although the intricate nature of trypanosome development in the fly has been recognized for more than a century, the molecular mechanisms are still mysterious, due in part to the experimental challenges posed by the tsetse fly. We found that overexpression of the T. brucei RNA-binding protein RBP6 in cultured non-infectious procyclic forms initiates differentiation into the developmental stages found in tsetse flies and culminates with the generation of infective metacyclics expressing the variant surface glycoprotein (VSG) coat. Our first goal will be to delineate the mechanism of action of RBP6. As RBP6 appears to be a "master regulator" triggering a cascade of events, it will be critical to identify the primary mRNA targets of RBP6. This will provide crucial information about gene products involved in the early stages of differentiation and for formulating a testable hypothesis about the cellular adaptations occurring in the transition from procyclic to epimastigotes forms. Our second goal will be to provide a transcriptomic and proteomic map of epimastigotes and metacyclics and to decode the biology of metacyclogenesis. Finally, the discovery of novel genes, besides VSG, required for metacyclic differentiation will be a major breakthrough toward deciphering how the process of acquisition of infectivity is brought about. Taken together our research plan provides unique opportunities to illuminate the differentiation program from procyclic to metacyclic and reveal the mode of action of an important RNA binding protein.