GP46 GENES AND PROTEIN EXPRESSION IN LEISHMANIA CHAGASI

大多数利什曼原虫物种，包括利什曼原虫查加西，在他们的 表面有一种丰富的、高度保守的糖蛋白，称为GP46或 PSA-2。关于GP46的不同分子量已在 在不同的利什曼原虫物种之间。GP46的功能是 未知，但GP46已被证明对小鼠有部分保护作用 对抗亚马逊利什曼原虫的挑战。在那些利什马尼亚 在已经研究过的物种中，GP46的基因组织是复杂的 由排列成簇的多个不同的基因组成。 在初步研究中，如参考文献1所述，我们发现 在查加西乳杆菌中，44和66 kDa版本的GP46的丰度增加 30倍于致病的前鞭毛体从低传染性发展到高传染性 感染性形式，但在弱化的前鞭毛体中 在发育过程中不会增加。存在两种GP46 RNA (2.8和4.8 kb)，这两种病毒在致病期间也都增加了30倍 前鞭毛体发育。然而，鉴于44和44的丰度 66 kDa的GP46相互之间在2倍以内，丰度为2.8 Kb RNA是4.8kb RNA的40倍多。核子跑动 实验表明，GP46基因的表达水平受细胞周期调控。 从转录上讲。利用稳定转基因的前鞭毛体进行的实验 与含有查加西乳杆菌GP46之一的不同区域的质粒 基因显示其3‘端非编码区赋予发育受调控的 富含一个报告基因/RNA。因此，这一行动的具体目标是 项目是：(1)确定GP46基因之间的关系 以及不同的GP46mRNAs和蛋白质的丰度，(2) 确定受调控的GP46表达缺失的分子基础 在弱化的前鞭毛体中，(3)鉴定和鉴定顺式和 参与发育调控的反式作用元件 以及(4)确定前处理、协同处理和联合检测是否存在差异。 RNA的处理或后处理调节增加的 以感染性形式表达丰富的GP46基因。这些研究是 旨在确定调节GP46的分子过程 表达，我们预计需要蛋白质的基本过程 这将是未来旨在开发新疗法的研究目标 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.