CELL CYCLE DYNAMICS OF THE TRYPANOSOME FLAGELLAR POCKET

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。我们正在努力了解非洲锥虫与其宿主之间的关系。我们的方法是对“鞭毛袋”（FP）进行分子和细胞的理解，这是锥虫细胞表面的一种特化，围绕着鞭毛从寄生虫表面突出的地方。这是所有锥虫体内和胞外分泌的部位，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起着重要作用。我们正在使用电子断层扫描技术，以大约6纳米的分辨率进行三维结构研究。我们的工作是围绕最近的发现，即人类低密度脂蛋白的一个组成部分，ApoL1，对一些非洲锥虫有细胞毒性，但对其他锥虫没有，这种差异取决于它们的内吞系统特有的蛋白质。初步结果表明，这种细胞毒性因子在FP处进入锥虫体内，但以某种方式导致细胞裂解和死亡。我们预期这种杀死锥虫的方法可用于医疗目的。了解血清因子对物种特异性和广谱锥虫杀伤的机制，将有助于深入了解宿主-寄生虫生物学，并有助于评估预防性治疗的新途径。因此，我们使用电子断层扫描检查了布氏体的FP，发现FP相关的膜成分包括网格蛋白包被的囊泡、小管和各种各样的膜结合室。收集了11个双轴层析图的数据，以三维方式重建这些隔室。我们现在正在努力开发标记技术，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性因子的途径。

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.