PATHWAYS REGULATING AMOEBIC CYST FORMATION

描述：（改编自申请人的摘要）：人体内的包囊形成 寄生虫溶组织内阿米巴不能在体外研究。相关 爬行类寄生虫E.在体外能成囊，可作为模型 系统研究内阿米巴包囊。两种糖抑制阿米巴 包囊形成过程半乳糖可防止阿米巴聚集， 在包囊形成之前，而N乙酰葡糖胺允许发生聚集， 仍然可以防止抗肿瘤囊肿的形成。这项建议会 研究半乳糖配体及其受体在包囊形成中的作用 过程与大肠杆菌GalNAc凝集素轻亚基同源。 histolytica已从E.入侵。急诊入侵基因产物 结合半乳糖和粘蛋白，似乎存在于阿米巴的表面， 可能介导了最初的细胞聚集步骤。镓封端 糖缀合物以浓度依赖性方式刺激包囊形成， 表明凝集素在寄生虫分化中的作用。的结构 凝集素和一个拟议的机制，调节成囊将在 这个提议。

DESCRIPTION: (Adapted from the Applicant'ps Abstract): Encystation in the human parasite Entamoeba histolytica cannot be studied in vitro. The related reptilian parasite, E. invadens, will encyst in vitro and can be used as model system to study encystation in Entamoeba. Two sugars inhibit the amebic encystation process. Galactose prevents the aggregation of ameba, which precedes encystation while N acetyl glucosamine allows aggregation to occur but still prevents the formation of osmotically resistant cysts. This proposal will study the role of galactose ligands and their receptor in the encystment process. An ortholog of the light subunit of the GalNAc lectin of E. histolytica has been cloned from E. invadens. The E. invadens gene product binds galactose and mucin, appears to be found on the surface of the ameba and likely mediates the initial cellular aggregation step. Gal-terminated glycoconjugates stimulate encystation in a concentration-dependent manner and suggest a role for the lectin in parasite differentiation. The structure of the lectin and a proposed mechanism of regulating encystation will be examined in this proposal.