STRUCTURE AND FUNCTION OF HOST CELL RECEPTORS FOR TRYPANOSOMA CRUZI

这项提案的长期目标是阐明 心脏细胞上作为锥虫受体的结构 克鲁兹T. cruzi是南美锥虫病的病原体， 这种疾病影响了南美洲和中美洲数百万人。 这种血液寄生虫的主要目标之一是心脏组织， 导致心脏骤停，经常伴随死亡。 通过输血传播的南美锥虫病病例增加 尽管死亡率和 由于这种血液寄生虫的发病率知之甚少，如果 关于T.克鲁兹我们发现 从心脏成肌细胞纯化的表面74 kDa糖蛋白， 特异于该分子的抗体抑制T.克氏锥鞭毛体 结合并内化到心脏成肌细胞中。这种糖蛋白 结合侵袭性锥鞭毛体，但不结合非侵袭性外鞭毛体 T的形式。cruzi和表达的细胞，可以入侵 锥鞭毛体，但不是不能被这种形式入侵的细胞 的寄生虫。鉴于这些发现，我们假设， 宿主74 kDa糖蛋白可能作为T.克鲁兹 在本提案中，我们将测试这一假设，我们将了解其 分子结构为此，我们提出以下具体建议： 目的：a）鉴定表达74 kDa蛋白的克隆， 小鼠心肌细胞表达cDNA文库，克隆人蛋白 从人心脏cDNA文库中获得DNA测序信息 从编码74 kDa蛋白质的两种DNA插入片段中，并预测其 氨基酸序列，B）表达和纯化重组的74 kDa 用于配体与锥虫结合研究的蛋白质，和c）测试 74 kDa蛋白作为T. cruzi 通过筛选T. 克鲁兹 预计这一提议将产生新的 关于膜的分子结构的信息和见解 心脏细胞上的一种蛋白质，可能作为这种受体发挥作用。 血液和心脏组织寄生虫此外，这些研究将有助于 作为研究哺乳动物表面蛋白作为受体的作用的模型 对于其他血液和组织寄生虫， 细胞-寄生虫识别。这些研究的意义在于， 它们将有助于T. 心脏细胞的cruzi识别，促进锥虫进入。这 信息是非常需要的分子干预， 心脏病

The long term goal of this proposal is to elucidate the molecular structures on heart cells that function as receptors for Trypanosoma cruzi. T. cruzi is the causative agent of Chagas' disease, a heart disease that affects millions of people in South and Central America. One of the major targets of this blood parasite is the heart tissue, causing cardiac arrest which is frequently accompanied by death. Increasing cases of Chagas' disease transmitted by blood transfusions have been reported in the United States and despite the mortality and morbidity attributed to this blood parasite very little is known, if any, about host cell receptors for T. cruzi. We have found that the purified surface 74 kDa glycoprotein from heart myoblasts and antibodies specific to this molecule inhibit T. cruzi trypomastigote binding and internalization into heart myoblasts. This glycoprotein binds to invasive trypomastigote but not to non-invasive epimastigote forms of T. cruzi and is expressed on cells that can be invaded by trypomastigotes but not on cells that can not be invaded by this form of the parasite. In view of these findings, we have hypothesized that the host 74 kDa glycoprotein may function as a receptor for T. cruzi. In this proposal we will test this hypothesis and we will learn its molecular structure. To this end, we propose the following specific aims: a) to identify clones expressing the 74 kDa protein from an expression cDNA library of mouse heart cells, clone the human protein from a human heart cDNA library and obtain DNA sequencing information from both DNA inserts encoding the 74 kDa protein and predict their amino acid sequence, b) to express and purify the recombinant 74 kDa protein for ligand binding studies to trypanosomes, and c) to test the ability of the 74 kDa protein to function as a receptor for T. cruzi by transfecting mammalian cell lines which can not be invaded by T. cruzi. It is anticipated that this proposal would generate new information and insights about the molecular structure of a membrane protein present on heart cells that may function as a receptor for this blood and heart tissue parasite. In addition, these studies will serve as a model to study the role of mammalian surface proteins as receptors for other blood and tissue parasites that may play an important role in cell-parasite recognition. The significance of these studies is that they will contribute to the establishment of the molecular basis of T. cruzi recognition by heart cells that promotes trypanosome entry. This information is very much needed for molecular intervention in this heart disease.