INSULIN-LIKE SIGNALING IN PARASITIC NEMATODE DEVELOPMENT

总结 寄生线虫感染了世界上很大一部分人口， 人类疾病的代价。 这些寄生虫以发育停滞的感染性幼虫感染宿主 （通常是第三阶段的幼虫，（L3 i）一旦进入宿主就恢复发育。借鉴 在秀丽隐杆线虫中的广泛相关发现，我们发现了明确的证据， 胰岛素样（ILS）和类固醇核激素受体（NHR）信号调节L3 i发育 在寄生线虫粪类圆线虫的感染过程之前和期间。 在这 更新申请，我们建议在S. stercoralis和启动新的研究的潜力，保守的类固醇NHR信号通路 作为这种寄生虫的治疗靶点我们的两个具体目标中的第一个是问胰岛素是否 信号传导调节S. L3 i的形成和维持。粪虫 具体来说，我们将确定 胰岛素样受体激酶Ss-AGE-2和PI 3激酶Ss-AGE-1是否阻断L3 i的阻滞 并促进其在宿主中的发育再激活， 和Ss-ILP-7分别促进L3 i的发育再激活和阻滞。 我们的方法将 包括分析由表达显性转基因构建体产生的表型， 这些分子在S.粪虫具体目标2将询问是否通过SS-12 -12发送信号 NHR增强了S.以及这种小分子受体是否可以 成为基于天然存在的类固醇或其类似物的化疗的靶点。 我们建议 鉴定Ss-beta-12的天然配体并比较它们在调节L3 i阻滞中的活性， 重活化C.线虫、D4-和D 7-达法膦酸（DA）。 我们将使用 化学抑制剂来探测S. stercoralis和使用沙鼠 感染模型，以确定施用Ss-daf-12抑制剂或DA是否可以预防 L3 i的发展，清除成虫感染和/或阻断暴发性自身感染， 人类类圆线虫病并发症。 这些实验将直接反映出歼-12的潜力 NHR在寄生线虫中作为化疗靶点发挥作用。

SUMMARY Parasitic nematodes infect a significant proportion of the world's population and exact an enormous toll of human illness. These parasites infect their hosts as developmentally arrested infective larvae (usually third-stage larvae, (L3i) that resume development once they enter the host. Drawing upon extensive relevant findings in Caenorhabditis elegans, we have uncovered definitive evidence that insulin-like (ILS) and steroid-nuclear hormone receptor (NHR) signaling regulate L3i development before and during the infective process in the parasitic nematode Strongyloides stercoralis. In this renewal application, we propose to complete our studies on regulation of L3i development by ILS in S. stercoralis and initiate new research on the potential of a conserved steroid NHR signaling pathway as a therapeutic target in this parasite. The first of our two Specific Aims asks whether insulin signaling regulates formation and maintenance of L3i by S. stercoralis. Specifically we will determine whether the insulin-like receptor kinase Ss-DAF-2 and the PI3 kinase Ss-AGE-1 block arrest of L3i and promote their developmental reactivation in the host and whether insulin-like peptides Ss-ILP-6 and Ss-ILP-7 promote developmental reactivation and arrest of L3i, respectively. Our approach will involve analyzing phenotypes that result from expressing dominant transgene constructs based on these molecules in S. stercoralis. Specific Aim 2 will ask whether signaling through the Ss-DAF-12 NHR augments regulatory ILS effects in S. stercoralis and whether this small molecule receptor could be a target for chemotherapy based on naturally occurring steroids or their analogs. We propose to identify the natural ligands of Ss-DAF-12 and compare their activity in regulating L3i arrest and reactivation to the DAF-12 ligands from C. elegans, D4- and D7-dafachronic acids (DA). We will use chemical inhibitors to probe endogenous NHR DAF-12 function in S. stercoralis and use a gerbil model of infection to determine whether administered Ss-daf-12 inhibitors or DA can prevent development of L3i, clear adult worm infections and/or block fulminant autoinfection, a potentially fatal complication of human strongyloidiasis. These experiments will directly reflect the potential of DAF-12 NHR function as a chemotherapeutic target in parasitic nematodes.