Insulin-like signaling in parasitic nematode development

寄生线虫使全世界数以百万计的人生病或衰弱。在大多数感染中， 第三幼虫期（L3 i）感染脊椎动物宿主。L3 i是过渡的、发育停滞的阶段， 当暴露于最终宿主中存在的线索时，其被重新激活。寄生虫的作用机制 调节L3 i的发展仍然不清楚，主要是由于缺乏现代分子生物学方法， 这些有机体。相比之下，在自由生活的线虫中调节L3形态发生的系统 秀丽隐杆线虫的特征很好。这些系统包括胰岛素/IGF信号转导 通路这项研究的总体目标是确定最近发现的胰岛素样 粪类圆线虫中的信号通路也调节寄生虫的发育， 一般来说线虫。S.选择粪虫作为模型是因为这种蠕虫具有交替的自由生活 循环，让人想起C中的持续发展。优雅这项建议的具体目标是，首先， 在粪类圆线虫中鉴定编码胰岛素样信号转导元件的关键基因。我们将 完成了我们对PI 3激酶编码基因pik-1的鉴定，pik-1是C. elegans年龄-1，和 寻找S。daf-28是调节C.优雅 其次，我们将研究从S. 粪虫这些研究的方法将强调异源基因转移到C. elegans 携带特定的胰岛素途径突变第三，我们将应用这些相同的方法来调查角色 胰岛素途径中间体在调节S.粪虫最后，我们将描述寄生虫- FKTF-1的特定结构/功能关系，并描述了这种转录的细胞内运输 因子和DAF-16直系同源物。嵌合基因构建体，其结合了 FKTF-1和FKTF-16将在突变体C中表达。elegans和S.对发育的影响 并评估亚细胞定位。FKTF-1的亚细胞定位将在以下关键点确定： 生活史，并与C. elegans的发展我们 最近在S. stercoralis将允许我们使用C.雅丽甘斯 一个遗传替代与同源转基因构建体的研究在S。粪菌本身

Parasitic nematodes sicken or debilitate millions of personsworldwide. In the majority of these infections, the third larval stage (L3i) infects the vertebrate host. L3i are transitional, developmental^ arrested stages, which are reactivated when exposed to cues present in the definitive host. Mechanisms by which parasites regulate L3i development remain unclear, due largely to the lack of modern molecular biological methods for these organisms. By contrast, systems regulating L3 morphogenesis in the free-living nematode Caenorhabditis elegans are well characterized. These systems include an insulin/IGF signal transduction pathway. The overall goal of the proposed study is to ascertain whether a recently discovered insulin-like pathway in Strongyloides stercoralis also regulates development in that parasite and, by analogy, in parasitic nematodes generally. S. stercoralis was chosen as a model because this worm has an alternate free-living cycle, reminiscent of continuous development in C. elegans. The specific aims of this proposal are, first, to identify key genes encoding insulin-like signal transduction elements in Strongyloides stercoralis. We will complete our characterization of the PI3 kinase-encoding gene pik-1, an ortholog of C. elegans age-1, and seek the S. stercoralis ortholog of daf-28, the insulin-like ligand regulating L3 development in C. elegans. Second, we will investigate the developmental function of insulin-like signal pathway intermediates from S. stercoralis. Methods for these studies will stress heterologous gene transfer into strains of C. elegans carrying specific insulin pathway mutations. Third, we will apply these same methods to investigate the roles of insulin pathway intermediates in regulating lifespan in S. stercoralis. Finally, we will delineate parasite- specific structure/function relationships in FKTF-1 and describe intracellular trafficking of this transcription factor and daf-16 ortholog during development. Chimeric gene constructs, combining functional domains of FKTF-1 and DAF-16 will be expressed in mutant C. elegans and in S. stercoralis and effects on development and subcellular localization assessed. Subcellular localization of FKTF-1 will be determined at key points in the parasite life cycle and compared to that of DAF-16 at analogous points in C. elegans' development. Our recent success with transgenesis in S. stercoralis will allow us to augment experiments using C. elegans as a genetic surrogate with studies of homologous transgene constructs in S. stercoralis itself.