Role of the intrinsically disordered protein PIR in Polycomb silencing and environmental responses in Arabidopsis

该项目的目标是揭示植物在干旱等恶劣条件下生存的分子基础。当植物经历一段干旱时期时，基因组中的基因亚组被一种名为Polycomb的蛋白质调节器关闭或沉默。这种沉默有助于植物保存关键的资源，以在干旱中生存。Polycomb如何使基因沉默的某些方面已经被了解，但Polycomb到底是如何针对正确的基因沉默以应对干旱仍然是一个谜。根据从最近研究中获得的线索，该项目将研究一种新发现的名为PIR的蛋白质，它可能提供干旱和多梳作用之间缺失的联系。了解这种联系可能会对农业产生广泛的影响，因为这些发现将有助于植物育种者开发能够在干燥环境中生长得更好的作物品种。该项目还将通过改进课堂环境中的有组织的主动学习活动，在入门和高级生物学课程中产生教育影响。此外，我们将开发和传播研究实验室模块，让高中生参与真实的研究体验。这些教育活动旨在促进不同群体的学生在科学领域的成功和留住，并有望有助于为未来的STEM工作做准备。在植物和动物中，多梳蛋白复合体长期以来一直被认为是关键的发育调节因子，并知道它们如何通过组蛋白修饰和染色质压缩来抑制基因表达。相比之下，人们对这些调控因子如何控制基因表达以响应外源线索的了解较少。本项目将使用模式植物拟南芥来研究干旱胁迫如何通过多梳抑制复合体2(PRC2)与另一种名为多梳相互作用抑制因子(PIR)的蛋白质相互作用来影响沉默。初步结果提供了证据，证明PIR与干旱胁迫反应有关，并与PrC2在遗传和物理上相互作用。这些观察将被跟踪以探索：干旱胁迫如何影响PIR/PRC2复合体在染色质上的招募和活性；PIR是否作为非化学计量的辅助PRC2成分发挥作用；以及干旱是否导致PIR，一种本质上无序的蛋白质，形成无膜相分离的核凝聚物，称为多梳体。总而言之，这些结果应该会在干旱反应和基于染色质的调控之间提供新的机制联系。该奖项由遗传机制计划(分子和细胞生物科学部)和植物基因组研究计划以及生理机制和生物力学计划(综合组织系统部)共同资助，均在生物科学局。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The goal of this project is to uncover the molecular basis for plant survival under harsh conditions, such as drought. When plants experience a dry spell, subsets of genes in the genome are turned off, or silenced, by a protein regulator called Polycomb. This silencing helps the plant conserve crucial resources to survive the drought. Some aspects of how Polycomb works to silence genes is understood, but exactly how Polycomb targets the correct genes to silence in response to drought is still a mystery. Following up on clues obtained from recent studies, this project will study a newly identified protein called PIR, which may provide the missing link between drought and Polycomb action. Understanding this connection could have broad impacts for agriculture, as the findings would help plant breeders develop crop varieties that can grow better in dry environments. The project will also have educational impact by improving structured active learning activities in classroom settings, in both introductory and advanced biology courses. In addition, we will develop and disseminate research laboratory modules for engaging high school students in authentic research experiences. The educational activities are aimed at enhancing the success and retention of diverse groups of students in science and are expected to contribute to preparation of a future STEM workforce.In plants and animals, Polycomb protein complexes have long been recognized as key developmental regulators and much is known about how they repress gene expression by histone modification and chromatin compaction. In contrast, less is understood about how these regulators control gene expression in response to exogenous cues. This project will use the model plant Arabidopsis thaliana to study how drought stress influences silencing through interaction of the Polycomb Repressive Complex 2 (PRC2) with another protein, called Polycomb Interacting Repressor (PIR). Preliminary results provided evidence that PIR is linked to drought stress response and that it interacts genetically and physically with PRC2. These observations will be followed up to explore: how drought stress influences recruitment and activity of PIR/PRC2 complexes on chromatin; whether PIR functions as a non-stoichiometric auxiliary PRC2 component; and whether drought leads PIR, which is an intrinsically disordered protein, to form membrane-less phase-separated nuclear condensates, known as polycomb bodies. Together, the results should provide new mechanistic links between drought response and chromatin-based regulation. This award was co-funded by the Genetic Mechanisms Program (Division of Molecular and Cellular Biosciences) and by the Plant Genome Research Program and the Physiological Mechanisms and Biomechanics Program (Division of Integrative Organismal Systems), all in the Directorate for Biological Sciences.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.