Characterization of endocrine signaling and RNAi pathways as mechanisms regulating environmental programming in C. elegans

越来越多的证据表明，胎儿和儿童期的经历通过以下方式影响人类的成人疾病： 组织特异性基因表达状态的变化和神经内分泌HPA功能的持续改变 轴线然而，在子宫内或儿童早期经历的环境线索的分子途径 导致与成人疾病相关的长期影响，以及它们如何在几代人中遗传， 没有被很好地理解。 秀丽隐杆线虫提供了一个独特的动物模型系统，其中探索 基因表达的环境编程机制，由于早期的经验。尽管成年 在发育早期经历环境压力的动物与那些 经历了有利的条件，这些成年人保留了他们的环境历史， 表现为基因表达和生育力的变化，这些变化与所经历的特定压力不同。 与对照组相比，经历早期饥饿的动物表现出生育力下降， 依赖于保守的内分泌信号传导途径和CSR-1 RNAi途径的上调。 有趣的是，这些内分泌信号途径，类固醇激素信号和脂肪酸代谢， 在缺乏生殖系的长寿动物中也上调。此外， 饥饿应激动物也通过HRDE-1 RNAi途径遗传至少两代。 这项提案的总体目标是研究如何促进无生殖细胞的长寿途径。 动物也可以调节经历营养应激的动物的繁殖。具体目标是 建议包括：1）研究类固醇信号传导和脂肪酸代谢在调节中的作用， 早期饥饿后的生育能力。这一目标提出了遗传和生化实验来验证这一假设 12/NHR作为一种“脂肪传感器”，根据储存的脂肪水平调节生殖细胞的生产， 直接调节具有促进生殖系增殖开始的功能的基因。2)使用生化 和发育遗传学实验，测试csr-1型低体型中增加的脂肪酸代谢是否 成年人的肥胖是由于肠道中CSR-1对脂肪基因的直接调节，或者是生育能力降低的间接影响。 在CSR-1亚型中，由于生殖系缺陷可能触发这些途径。3)确定机制 在经历营养应激的动物后代中降低生育力的遗传。实验将测试 类固醇信号和脂肪酸代谢基因是否也在F1后代中上调。HRDE-1 相关的siRNA也将在后代中进行深度测序，以鉴定有助于基因表达的靶基因。 降低生育力表型。总之，这些实验将研究如何促进体细胞 无生殖系动物的寿命也可以调节生育能力，这是由于早期生活饥饿，以及RNAi如何影响生育能力。 代谢途径有助于代谢程序的遗传。

Increasing evidence suggests that fetal and childhood experiences impact adult disease in humans through changes in tissue-specific gene expression states and sustained altered function of the neuroendocrine HPA axis. However, the molecular pathways by which environmental cues experienced in utero or early childhood result in long-lasting effects associated with adult disease, and how they can be inherited over generations, are not well understood. Caenorhabditis elegans nematodes provide a unique animal model system in which to explore the mechanisms of environmental programming of gene expression due to early experience. Although adult animals that experienced environmental stress early in development appear grossly identical to animals that experienced favorable conditions, these adults retain a cellular memory of their environmental history that is manifested by changes in gene expression and fertility that are distinct for the particular stress experienced. Animals that experienced early-life starvation exhibited decreased fertility compared to controls, which is dependent upon the upregulation of conserved endocrine signaling pathways and the CSR-1 RNAi pathway. Interestingly, these endocrine signaling pathways, steroid hormone signaling and fatty acid metabolism, are also upregulated in long-lived animals lacking a germ line. In addition, the reduced fertility phenotype of starvation-stressed animals is also inherited for at least two generations via the HRDE-1 RNAi pathway. The overall goal of this proposal is to investigate how pathways that can promote longevity in germline-less animals can also modulate reproduction in animals that experienced nutritional stress. The specific aims of this proposal include: 1) investigate the roles of steroid signaling and fatty acid metabolism in the regulation of fertility after early-life starvation. This aim proposes genetic and biochemical experiments to test the hypothesis that DAF-12/NHR acts as a “fat sensor” to modulate germ line production based on levels of stored fat by directly regulating gene(s) with functions in promoting the onset of germline proliferation. 2) Using biochemical and developmental genetics experiments, test whether the increased fatty acid metabolism in csr-1 hypomorph adults is due to direct regulation of fat genes by CSR-1 in the intestine, or an indirect effect of reduced fertility in the csr-1 hypomorph, as germ line defects may trigger these pathways. 3) Determine the mechanisms of inheritance for reduced fertility in progeny of animals that experienced nutritional stress. Experiments will test whether steroid signaling and fatty acid metabolism genes are also upregulated in F1 progeny. HRDE-1 associated siRNAs will also be deep sequenced in the progeny to identify target genes contributing to the reduced fertility phenotype. Together, these experiments will investigate how pathways that promote somatic longevity in germline-less animals can also modulate fertility due to early life starvation, and how RNAi pathways contribute to inheritance of metabolic programming.