Mechanisms underlying functional redundancy of plant CRWN proteins

在植物界，核基质组成蛋白（NMCP）作为核纤层蛋白类似物发挥功能，调节核形态和核周染色质束缚。它们还通过与转录因子和染色质重塑因子相互作用参与基因表达调控。先前的遗传学研究表明，拟南芥中的四个NMCP，即CRWN，对植物完成其生命周期至关重要。然而，在这些CRWN中，只有CRWN 1被深入研究。CRWN如何在分子水平上相互补充功能还知之甚少。在我们最近的实验中，我们在苗期检测了crwn 1 crwn 2 crwn 4三重突变体，与双突变体相比，其表现出严重的生长缺陷。RNA-seq分析表明，三重突变体类似于受到病原体攻击的野生型植物。有趣的是，我们发现CRWN 2蛋白在不同的遗传背景中显示出不同的核定位模式。在野生型植物中，CRWN 2蛋白形成均匀分布在核质中的斑点，但它们在crwn 1 crwn 4双突变体中特异性地定位于核外围。根据这一发现，在本项目中，通过采用尖端的基因组学和蛋白质组学方法，我们的目标是研究决定CRWN 2特异性核周定位的分子机制。我们还旨在更好地了解CRWN 2如何覆盖CRWN 1和CRWN 4在核外围的损失。

In the plant kingdom, nuclear matrix constituent proteins (NMCPs) function as nuclear lamin analogs, which regulate nuclear morphology and perinuclear chromatin tethering. They are also involved in gene expression regulation via interacting with transcription factors and chromatin remodelers. Previous genetic studies have revealed that the four NMCPs in Arabidopsis, named CROWDED NUCLEI (CRWN), are vital for plants to complete their life cycle. However, among these CRWNs, only CRWN1 has been intensively studied. How CRWNs functionally complement each other on a molecular level is poorly understood. In our recent experiments, we examined crwn1 crwn2 crwn4 triple mutants at a seedling stage, which show severe growth defects compared to double mutants. RNA-seq analyses indicate that the triple mutants resemble wild-type plants that were under pathogen attack. Interestingly, we found that CRWN2 proteins display distinct nuclear localization patterns in different genetic backgrounds. In wild-type plants, CRWN2 proteins formed speckles that were distributed evenly in the nucleoplasm, but they became specifically localized at the nuclear periphery in crwn1 crwn4 double mutants. Following this finding, in this project, by employing cutting-edge genomic and proteomic methods, we aim to investigate the molecular mechanisms determining CRWN2’s specific perinuclear localization. We also aim to gain a better understanding of how CRWN2 covers the loss of CRWN1 and CRWN4 at the nuclear periphery.