GP46 GENES AND PROTEIN EXPRESSION IN LEISHMANIA CHAGASI

大多数利什曼原虫物种，包括恰加斯利什曼原虫，在它们的 表面有一个丰富的，高度保守的糖蛋白，称为GP 46或 PSA-2。 GP 46的不同分子量已经在 以及不同种类的利什曼原虫。 GP 46的功能是 未知，但GP 46已被证明可以部分保护小鼠 对抗亚马逊利什曼原虫的攻击 在那些利什曼原虫 在已研究的物种中，GP 46基因组织是复杂的 并且由多个不相同的基因簇组成。 在初步研究中，如参考文献1所述，我们发现， 在洛恰加斯，GP 46的44和66 kDa版本的丰度增加， 30-随着毒性前鞭毛体从感染性较低发展到感染性较高， 感染形式，但在减毒前鞭毛体中，GP 46丰度 在发展过程中不会增加。 存在两种GP 46 RNA (2.8和4.8 kb），并且在毒性期间两者也增加30倍 前鞭毛体发育 然而，尽管44和 66 kDa GP 46的丰度在彼此的2倍内，2.8 kDa GP 46的丰度在彼此的2倍内。 kb RNA比4.8 kb RNA大40倍。 核连续运转 实验表明，GP 46 mRNA水平是在 转录。 使用稳定转染的前鞭毛体的实验 与含有L.恰加斯GP 46 基因显示，它的3' UTR赋予发育调控的 报告基因/RNA。 因此，这一具体目标 本研究的主要目的是：（1）确定GP 46基因之间的相互关系 以及不同GP 46 mRNA和蛋白质的丰度，（2） 确定GP 46表达调控缺失的分子基础 在减毒前鞭毛体中，（3）鉴定和表征顺式和 参与发育调节的反式作用元件 GP 46 mRNA丰度，和（4）确定是否预处理，共- RNA的加工或后加工介导了增加的 感染形式中GP 46 mRNA的丰度。 这些研究 旨在确定调节GP 46的分子过程， 表达，我们预期需要蛋白质的基本过程 这将是未来研究新疗法的目标， 预防内脏利什曼病。

Most Leishmania species, including Leishmania chagasi, possess on their surface an abundant, highly conserved, glycoprotein called GP46 or PSA-2. Different molecular weights for GP46 have been reported within and among different Leishmania species. The function of GP46 is unknown, but GP46 has been shown to confer partial protection of mice against challenge with Leishmania amazonensis. In those Leishmania species where it has been studied, the GP46 gene organization is complex and consists of multiple, non-identical, genes arranged in clusters. In Preliminary studies and as described in reference 1, we found that in L. chagasi the abundance of 44 and 66 kDa versions of GP46 increases 30-fold as virulent promastigotes develop from less infectious to highly infectious forms, but in attenuated promastigotes the GP46 abundance does not increase during development. Two species of GP46 RNA exist (2.8 and 4.8 kb), and both also increase 30-fold during virulent promastigote development. However, whereas the abundances of the 44 and 66 kDa GP46 are within 2-fold of each other, the abundance of the 2.8 kb RNA is 40-fold more than that of the 4.8 kb RNA. Nuclear run-on experiments indicate that the GP46 mRNA levels are regulated post- transcriptionally. Experiments using promastigotes stably transfected with plasmids containing various regions of one of the L. chagasi GP46 genes showed that its 3' UTR confers a developmentally regulated abundance to a reporter gene/RNA. Thus, the specific aims of this project are to: (1) determine the relationships between the GP46 genes and the abundances of the different GP46 mRNAs and proteins, (2) determine the molecular basis for the loss of regulated GP46 expression in attenuated promastigotes, (3) identify and characterize cis- and trans-acting elements that participate in the developmental regulation of GP46 mRNA abundance, and (4) determine whether pre-processing, co- processing or post-processing of the RNA mediates the increased abundance of GP46 mRNA in the infectious form. These studies are intended to identify the molecular processes that regulate GP46 expression, fundamental processes that we expect will require proteins which will be targets for future research aimed at new treatments and prevention of visceral leishmaniasis.