Protein arginine methylation in nuclear organization, function, and stress response

翻译后修饰扩大了给定基因组的表型范围，从而提高了细胞和生物的适应性。蛋白质精氨酸甲基转移酶(PRMT)修饰精氨酸残基，调节转录、剪接、翻译和基因组完整性；细胞中4000多种精氨酸甲基化蛋白具有多种功能。最近的进展使得识别PRMT底物成为可能；然而，我们对甲基精氨酸的效应器、下游识别和功能的了解仍然有限。大多数甲基精氨酸修饰的蛋白质定位于细胞核、细胞质中，也有一些在有毒刺激下的应激颗粒中发现。PRMT酶本身存在于几乎所有的细胞室中。虽然有大量关于精氨酸甲基化在细胞质和应激颗粒中的作用的文献，但对甲基精氨酸在细胞核中的分布和动态知之甚少，大多数精氨酸甲基化蛋白驻留在细胞核中。我们将使用共聚焦显微镜和超分辨显微镜研究精氨酸甲基化的核结构及其在应激反应中的动力学。我们的初步数据表明，在依赖于蛋白质-蛋白质和蛋白质-RNA相互作用的离散核结构中，甲基精氨酸含量很高。精氨酸残基在蛋白质-蛋白质和蛋白质-RNA相互作用中起着关键作用；因此，精氨酸的甲基化可以显著影响建立在这些相互作用上的细胞结构。我们将使用选择性抑制剂来调节PRMT酶的活性，以确定精氨酸甲基化如何影响诸如副冠状突起等应激反应核结构中的分子相互作用力。为了实现这一点，我们将使用现代方法来评估选择性隔室中蛋白质-蛋白质和蛋白质-RNA的相互作用，以及识别新的甲基精氨酸识别模块。我们的研究将为深入了解精氨酸甲基化的分子机制、其动态调节以及其在应激反应的核生物学中的作用提供依据。最后，在我们的研究计划中，学员将获得在多学科环境中学习显微镜、生物化学、分子和细胞生物学的各种技能，这将使他们能够在未来的职业生涯中取得成功，并为加拿大的知识经济做出贡献。

Post-translational modifications expand the phenotype range of a given genome, thus increasing cellular and organismal adaptability. Protein arginine methyltransferases (PRMT) modify arginine residues to regulate transcription, splicing, translation, and genome integrity; diverse functions conferred by over 4000 arginine methylated proteins in cells. Recent progress enabled the identification of PRMT substrates; however, our knowledge of the effectors, downstream recognition, and function of methyl-arginine remains limited. Most methyl-arginine modified proteins localize in the nucleus, cytoplasm, and some are found in stress granules upon toxic stimuli. PRMT enzymes themselves are found in almost all cellular compartments. While a large body of literature exists on the role of arginine methylation in the cytoplasm and stress granules, little is known about the distribution and dynamics of methyl-arginine in the nucleus, where most arginine methylated proteins reside. We will investigate the nuclear architecture of arginine methylation and its dynamics in stress response using confocal and super-resolution microscopy. Our preliminary data indicates a high abundance of methyl-arginine in discrete nuclear structures that rely on protein-protein and protein-RNA interactions. Arginine residues play critical roles in the protein-protein and protein-RNA interactions; thus, methylation of arginines can dramatically affect the cellular structures built on these interactions. We will modulate the PRMT enzyme activity using selective inhibitors to determine how arginine methylation influences the molecular interaction forces in such model, stress-responsive nuclear structures as paraspeckles. To achieve this, we will employ modern methods to assess protein-protein and protein-RNA interactions in selective compartments as well as identify novel methyl-arginine recognition modules. Our research will provide insights into the molecular mechanism of arginine methylation, the regulation of its dynamics, and its role in the nuclear biology of the stress response. Finally, in our research program, trainees will acquire a diverse set of skills in microscopy, biochemistry, molecular, and cell biology learning in a multidisciplinary environment that will enable them to succeed in their future careers and contribute to Canada's knowledge-based economy.