CELL CYCLE DYNAMICS OF THE TRYPANOSOME FLAGELLAR POCKET

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。我们正在努力了解非洲锥虫和它们的宿主之间的关系。我们的方法是追求对“鞭毛袋”(FP)的分子和细胞理解，这是锥虫细胞表面的一种特化，它包围着鞭毛从寄生虫表面突出的地方。这是所有锥虫内吞和胞吐的场所，因此它在这种寄生虫避免宿主获得性免疫反应攻击的策略中发挥作用。我们正在使用电子断层摄影术来进行大约6纳米分辨率的3-D结构研究。我们的工作是围绕最近的一项发现进行的，即人类低密度脂蛋白的一种成分APOL1对一些非洲锥虫具有细胞毒性，而对其他非洲锥虫则没有，这种差异取决于一种特定于非洲锥虫内吞系统的蛋白质。初步结果表明，这种细胞毒性因子在FP进入锥虫体内，但以某种方式导致细胞裂解和死亡。我们预计这种杀死锥虫的方法可能被用于医疗目的。了解血清因子对特定物种和广谱锥虫的杀灭机制将有助于深入了解宿主-寄生虫生物学，并将有助于评估预防治疗的新途径。因此，我们使用电子断层扫描来检查布氏毛滴虫的FP，发现FP相关的膜成分包括笼蛋白包裹的囊泡、微管蛋白和各种膜结合的隔室。收集了11个双轴断层图像的数据，以3D方式重建这些间隔室。我们现在正致力于开发标记技术，以表征所有的内吞途径，包括那些从哺乳动物血清中内化细胞毒因子的途径。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We are working to understand the relationships between African trypanosomes and their hosts. Our approach is to pursue a molecular and cellular understanding of the "Flagellar Pocket" (FP), a specialization of the trypanosome cell surface that surrounds the place where the flagellum protrudes from the parasite's surface. This is the site of all trypanosome endo- and exocytosis, so it plays a role in this parasite's strategies for avoiding attack by the host's acquired immune response. We are using electron tomography to pursue structural studies at about 6 nm resolution in 3-D. Our work is organized around the recent finding that a component of human LDL, ApoL1, is cytotoxic to some African trypanosomes but not others, the difference depending on a protein that is specific to their endocytic systems. Preliminary results suggest that this cytotoxic factors enters trypanosomes at the FP but somehow lead to cell lysis and death. We anticipate that this way of killing trypanosomes could be exploited for medical purposes. An understanding of mechanisms for both species-specific and broad-spectrum trypanosome killing by serum factors should provide insight into host-parasite biology and will assist in assessing novel routes to preventative treatments. We have therefore used electron tomography to examine the FP of T. brucei and found that FP-associated membrane components include clathrin-coated vesicles, tubulins, and a wide variety of membrane-bounded compartments. Data for 11 dual-axis tomograms have been collected to reconstruct these compartments in 3D. We are now working to develop labeling techniques that will characterize all the endocytic pathways, including those that internalize cytotoxic factors from mammalian serum.