INSULIN-LIKE SIGNALING IN PARASITIC NEMATODE DEVELOPMENT

描述（由申请人提供）：寄生线虫感染了世界上很大一部分人口，并造成了巨大的人类疾病。 这些寄生虫作为发育停滞的感染性幼虫（通常为第三阶段幼虫，（L3 i））感染它们的宿主，一旦它们进入宿主就恢复发育。利用秀丽隐杆线虫中广泛的相关发现，我们发现了明确的证据，即胰岛素样（ILS）和类固醇核激素受体（NHR）信号调节L3 i的发展之前和期间的寄生线虫粪类圆线虫感染过程。 在本更新申请中，我们建议完成我们在S. stercoralis和启动新的研究的潜力保守的类固醇NHR信号通路作为一个治疗目标，在这种寄生虫。我们的两个具体目标中的第一个是询问胰岛素信号是否调节S.粪虫 具体而言，我们将确定胰岛素样受体激酶Ss-ILP-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活化，以及胰岛素样肽Ss-ILP-6和Ss-ILP-7是否分别促进L3 i的发育再活化和阻滞。 我们的方法将涉及分析表型，从表达显性转基因构建体的基础上，这些分子在S。粪虫具体目标2将询问通过Ss-NHR-12的信号传导是否增强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-Bu-12的天然配体，并将它们在调节L3 i停滞和再激活中的活性与来自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.粪类圆线虫感染并使用沙鼠感染模型来确定施用的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（一种潜在的人类类圆线虫病的致命并发症）。 这些实验将直接反映β-12 NHR在寄生线虫中作为化疗靶标的功能潜力。

DESCRIPTION (provided by applicant): 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.