Novel Role for Piwi/piRNA pathway in developmental robustness

Piwi/piRNA 通路在发育稳健性中的新作用

• 批准号: 8521308
• 负责人: VAMSI GANGARAJU
• 金额: $ 9万
• 依托单位: YALE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-02 至 2013-12-19
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8521308
• 关键词: Affect; Apoptosis; Aubergine; Binding; Biochemical; Biogenesis; Biological Assay; Biological Models; Cell Nucleus; Cell physiology; Cells; Chromatin; Column Chromatography; Complex; DNA Fragmentation; Development; Developmental Biology; Disease; Drosophila genus; Embryo; Embryonic Development; Enhancers; Environment; Environmental Pollutants; Epigenetic Process; Evolution; Eye Development; Female sterility; Foundations; Functional RNA; Functional disorder; Future; Gene Expression Profile; Generations; Genes; Genetic; Genetic Screening; Genotype; Germ Lines; Goals; Human; Human Development; Humulus; Industrial Waste; Inherited; Learning; Light; Maintenance; Mediating; Molecular; Molecular Chaperones; Mutagenesis; Organism; Pathway interactions; Peptides; Phosphorylation; Play; Population; Process; Proteins; Regulation; Research; Resources; Role; Stem cells; Stress; Testing; Time; Toxic effect; Variant; Work; chromium hexavalent ion; combinatorial; dosage; epigenetic variation; genetic analysis; genome-wide; human disease; in vivo; insight; novel; piRNA; pollutant; prevent; protein crosslink; research study; self-renewal; tool

DESCRIPTION (provided by applicant): The long term goal of our proposal is to delineate the mechanisms by which Piwi/piRNA pathway normalizes phenotypic variation induced by severe environmental stress and inherent genotype variations. Canalization or developmental robustness provides a framework in which organisms resist displaying phenotypic variation in the face of combined genotype variations and severe environmental stress. Recent research has shown that Hsp90, a molecular chaperone, plays a critical role in canalization. Despite the known role for Hsp90, the lack of a detailed molecular mechanism underlying canalization has provoked great debate for decades. This lab recently validated the existence of 'canalization' and uncovered a major molecular pathway involving Piwi, Hsp90 and Hop. Using a sensitized eye development assay, a reduction in the maternal dosage of Drosophila Piwi and Aubergine was demonstrated, which bind to novel germline-enriched small non-coding RNAs called piRNAs, induces phenotypic variations that can be fixed in a population and stably inherited in later generations. The study also showed that Piwi directly interacts with Hop and Hsp90 and functions in the same pathway as Hsp90 in suppressing phenotypic variations. Further, it was demonstrated for the first time that Piwi becomes phosphorylated in an Hsp90 dependent manner, thus providing insights into how Hsp90 may modulate Piwi's function in canalization. Crucially, this study also revealed two related yet distinct Piwi/piRNA pathway-dependent mechanisms responsible for suppression of phenotypic variation: epigenetic silencing of inherent genotype variations and suppression of transposon-mediated mutagenesis. This work revealed a framework of a pathway that suppresses phenotypic variation. The working hypothesis is that Hsp90 and Hop modulate Piwi function via its phosphorylation which then modulates Piwi function in canalization. By further unraveling the inner workings of each step of this pathway, we aim to shed light on the mechanisms that mediate this very important, yet poorly understood cellular phenomenon. The aims of the proposal are to- 1) Discover new components that mediate and/or regulate Piwi function in canalization using genetic screens, 2) Unravel the biochemical mechanism of Piwi mediated epigenetic regulation in canalization and finally 3) Understand how Hsp90-Piwi/piRNA pathway counteracts environmental stress induced by industrial pollutants like hexavalent chromium (CrVI). Piwi proteins are present from protozoans to humans with conserved functions in stem cell self-renewal and germ line maintenance. However their role in suppression of phenotypic variation is a novel function that requires further characterization. Unraveling the mechanism by which Piwi functions in canalization using Drosophila as a model system understanding its roles in humans and learning how the dysfunction of this process might affect human will provide the necessary context for development and cause diseases.

描述（由申请人提供）： 我们提案的长期目标是描述 Piwi/piRNA 途径使由严重环境应激和固有基因型变异引起的表型变异正常化的机制。运河化或发育稳健性提供了一个框架，使生物体在面对组合的基因型变异和严重的环境压力时抵抗表现出表型变异。最近的研究表明，Hsp90 作为一种分子伴侣，在运河化过程中发挥着关键作用。尽管 Hsp90 的作用已为人所知，但由于缺乏详细的运河化分子机制，几十年来一直引发了激烈的争论。该实验室最近验证了“管道化”的存在，并发现了涉及 Piwi、Hsp90 和 Hop 的主要分子途径。使用致敏眼发育测定，证明果蝇 Piwi 和茄子的母体剂量减少，它们与称为 piRNA 的新型种系富集的小非编码 RNA 结合，诱导表型变异，这些变异可以在群体中固定并在群体中稳定遗传。后世。研究还表明，Piwi 直接与 Hop 和 Hsp90 相互作用，并以与 Hsp90 相同的途径发挥作用，抑制表型变异。此外，首次证明 Piwi 以 Hsp90 依赖性方式磷酸化，从而深入了解 Hsp90 如何调节 Piwi 在运河化中的功能。至关重要的是，这项研究还揭示了两种相关但不同的 Piwi/piRNA 途径依赖性机制，负责抑制表型变异：固有基因型变异的表观遗传沉默和转座子介导的诱变的抑制。这项工作揭示了抑制表型变异的途径框架。工作假设是 Hsp90 和 Hop 通过其磷酸化调节 Piwi 功能，然后调节管道形成中的 Piwi 功能。通过进一步揭示该途径每个步骤的内部运作机制，我们的目标是阐明介导这一非常重要但仍知之甚少的细胞现象的机制。该提案的目的是 - 1) 使用遗传筛选发现介导和/或调节管道化中 Piwi 功能的新成分，2) 揭示管道化中 Piwi 介导的表观遗传调控的生化机制，最后 3) 了解 Hsp90-Piwi/ piRNA 途径可以抵消六价铬 (CrVI) 等工业污染物引起的环境压力。 Piwi 蛋白存在于原生动物和人类中，在干细胞自我更新和生殖系维持方面具有保守功能。然而，它们在抑制表型变异方面的作用是一种新功能，需要进一步表征。使用果蝇作为模型系统来揭示 Piwi 在运河化中发挥作用的机制，了解其在人类中的作用，并了解该过程的功能障碍如何影响人类，将为发育和引起疾病提供必要的背景。