The molecular mechanism for trypanosome cell death induced by ApoLI and its inactivation in human infective T. b. rhodesiense.

ApoLI 诱导锥虫细胞死亡的分子机制及其在人类感染性锥虫中的失活。

• 批准号: MR/P001424/1
• 负责人: Matthew Higgins
• 金额: $ 110.77万
• 依托单位: University of Oxford
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2016
• 资助国家: 英国
• 起止时间: 2016 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FP001424%2F1
• 关键词: molecular; mechanism; trypanosome; cell; death

Trypanosomes are deadly, single celled parasites that are injected into the blood of humans, domestic livestock and wildlife when bitten by infected tsetse flies. They cause sleeping sickness in humans and wasting diseases in livestock, including nagana in cattle. These diseases have significant impact in sub-Saharan Africa. They lead to thousands of human deaths and cause significant human suffering by reducing the productivity of livestock. Most species of African trypanosomes cannot infect humans, due to two molecular complexes found in human blood, known as trypanolytic factors. These contain a shared component, apolipoprotein LI (ApoLI) which kills the trypanosomes. ApoLI can punch holes in the membranes of the parasite, leading to death of the cell. The two subspecies of trypanosome that infect humans and cause sleeping sickness are able to inactivate ApoLI and can therefore survive in human blood and cause disease.How ApoLI kills trypanosomes is not well understood. It is well established that ApoLI punches holes in membranes but it is not clear which membranes within the trypanosome cell are damaged. Some studies suggest that ApoLI bursts the lysosome, a compartment of the cell used to degrade cellular components. Others suggest that it punches holes in the outer cell membrane, while further studies suggest that it is the mitochondria, the energy 'power-houses' of the cell, that are damaged. We will use the latest microscopy methods to observe ApoLI as it moves around the cell, and to see what parts of the cell are affected, and how they are killed.The mechanism used by ApoLI to punch holes is also not well understood. How does it interact with membranes and how does it form pores? How are these pores regulated? These questions are important for understanding how ApoLI kills trypanosomes. They are also important in understanding the natural function of ApoLI in the human body, as it is known that changes in ApoLI are associated with late-onset kidney disease. We will use structural biology methods to understand what ApoLI looks like, and to perform a variety of studies to see the mechanism by which it forms pores.We will also study one of the two human infective species of trypanosome, Trypanosoma brucei rhodesiense. This parasite can resist the toxic effects of ApoLI because of the presence of a single molecule, the serum resistance associated protein, SRA. We have shown that SRA can interact directly with ApoLI under a variety of conditions and now aim to determine exactly how it inactivates ApoLI. Does it bind to ApoLI to prevent it from getting to the region of the cell in which it mediates its toxic effects? Or does it bind to ApoLI and prevent it from forming pores? Or perhaps it is both? We will again use structural biology methods to understand exactly how ApoLI interacts with SRA, and how it stops pore formation by ApoLI. We will also use the latest microscopy methods to investigate how SRA moves around within trypanosomes that are exposed to ApoLI.These studies will provide molecule detail to allow us to understand how ApoLI kills trypanosomes and how human infective trypanosomes become resistant to this toxin. This has the potential to help us to design new therapeutics to prevent sleeping sickness. By understanding how SRA binds to and inhibits ApoLI, we can design new versions of ApoLI that are resistant to SRA-mediated inactivation. These can be supplied directly to sleeping sickness patients to kill trypanosomes. We can also develop small molecules that block the SRA-ApoLI interaction, allowing the bodies natural ApoLI-mediated defenses to kill the parasite. Finally, transgenic cattle are being developed which contain ApoLI to prevent trypanosome growth. Using versions of ApoLI which are resistant to SRA-mediated inactivation will decrease the chance of these cattle being infected and providing a reservoir for the growth and development of human infective trypanosomes.

锥虫是一种致命的单细胞寄生虫，当被感染的采采蝇叮咬时，会被注入人类、家畜和野生动物的血液中。它们会导致人类昏睡病和牲畜消耗性疾病，包括牛的长形病。这些疾病对撒哈拉以南非洲地区产生了重大影响。它们导致数千人死亡，并通过降低牲畜的生产力而给人类带来巨大痛苦。大多数非洲锥虫物种不能感染人类，这是由于在人类血液中发现的两种分子复合物，称为锥虫分解因子。它们含有一个共同的成分，载脂蛋白LI（ApoLI），可以杀死锥虫。ApoLI可以在寄生虫的膜上穿孔，导致细胞死亡。感染人类并引起昏睡病的锥虫的两个亚种能够感染ApoLI，因此可以在人类血液中存活并引起疾病。ApoLI如何杀死锥虫尚不清楚。已经确定ApoLI在膜上打孔，但不清楚锥虫细胞内的哪些膜受损。一些研究表明，ApoLI破坏溶酶体，溶酶体是细胞中用于降解细胞成分的一个区室。其他人认为它在细胞外膜上打了洞，而进一步的研究表明，它是线粒体，细胞的能量“发电站”，被损坏了。我们将使用最新的显微镜方法来观察ApoLI在细胞周围移动时的情况，并观察细胞的哪些部分受到影响，以及它们是如何被杀死的。ApoLI打孔的机制也没有得到很好的理解。它是如何与细胞膜相互作用的，又是如何形成孔隙的？这些毛孔是如何调节的？这些问题对于理解ApoLI如何杀死锥虫很重要。它们对于理解ApoLI在人体中的自然功能也很重要，因为已知ApoLI的变化与晚发性肾病相关。我们将使用结构生物学方法来了解ApoLI的样子，并进行各种研究以了解它形成孔的机制。我们还将研究两种人类感染性锥虫之一，布氏锥虫罗得西亚锥虫。这种寄生虫可以抵抗ApoLI的毒性作用，因为存在单一分子，血清抗性相关蛋白SRA。我们已经证明，SRA可以在各种条件下直接与ApoLI相互作用，现在的目标是确定它是如何灭活ApoLI的。它是否与ApoLI结合以阻止其到达介导其毒性作用的细胞区域？或者它与ApoLI结合并阻止它形成毛孔？或者两者都是？我们将再次使用结构生物学方法来确切地理解ApoLI如何与SRA相互作用，以及它如何阻止ApoLI形成孔。我们还将使用最新的显微镜方法来研究SRA如何在暴露于ApoLI的锥虫内移动。这些研究将提供分子细节，使我们能够了解ApoLI如何杀死锥虫以及人类感染性锥虫如何对这种毒素产生抗性。这有可能帮助我们设计新的治疗方法来预防昏睡病。通过了解SRA如何结合并抑制ApoLI，我们可以设计新版本的ApoLI，其对SRA介导的失活具有抗性。这些可以直接提供给昏睡病患者杀死锥虫。我们还可以开发出阻断SRA-ApoLI相互作用的小分子，使身体能够通过ApoLI介导的天然防御来杀死寄生虫。最后，正在开发含有ApoLI以防止锥虫生长的转基因牛。使用对SRA介导的灭活具有抗性的ApoLI版本将降低这些牛被感染的机会，并为人类感染性锥虫的生长和发育提供储存库。

项目成果

A Receptor's Tale: An Eon in the Life of a Trypanosome Receptor.

一个受体的故事：锥虫受体生命中的eon。

• DOI: 10.1371/journal.ppat.1006055
• 发表时间: 2017-01
• 期刊: PLoS pathogens
• 影响因子: 6.7
• 作者: Higgins MK;Lane-Serff H;MacGregor P;Carrington M
• 通讯作者: Carrington M

O-h what a surprise.

哦，真是一个惊喜。

• DOI: 10.1038/s41564-018-0211-x
• 发表时间: 2018
• 期刊: Nature microbiology
• 影响因子: 28.3
• 作者: Carrington M

Evolutionary diversification of the trypanosome haptoglobin-haemoglobin receptor from an ancestral haemoglobin receptor.

锥虫触珠蛋白-血红蛋白受体从祖先血红蛋白受体的进化多样化。

• DOI: 10.7554/elife.13044
• 发表时间: 2016
• 期刊: eLife
• 影响因子: 7.7
• 作者: Lane-Serff H

A single dose of antibody-drug conjugate cures a stage 1 model of African trypanosomiasis

单剂抗体药物偶联物治愈非洲锥虫病第一阶段模型

• DOI: 10.1101/547208
• 发表时间: 2019
• 作者: MacGregor P

High-throughput hit-squad tackles trypanosomes

高通量打击小队应对锥虫

• DOI: 10.1016/j.pt.2021.07.005
• 发表时间: 2021
• 期刊: Trends in Parasitology
• 影响因子: 9.6
• 作者: Cook A