Tucker Sara K, McLaurin Douglas M, Hebert Michael D
Department of Cell and Molecular Biology, The University of Mississippi Medical Center, Jackson, MS 39216-4505, USA.
J Cell Sci. 2024 Dec 1;137(23). doi: 10.1242/jcs.263447. Epub 2024 Dec 11.
Cajal bodies (CBs) are membraneless organelles whose mechanism of formation is still not fully understood. Many proteins contribute to the formation of CBs, including Nopp140 (NOLC1), WRAP53 and coilin. Coilin is modified on multiple different lysine residues by SUMO, the small ubiquitin-like modifier. In addition to its accumulation in CBs, coilin is also found in the nucleoplasm, where its role is still being evaluated. Here, we demonstrate a novel mechanism of CB regulation by examining the interaction changes of coilin when its SUMOylation is disrupted. The impact of global SUMOylation inhibition and targeted disruption of coilin SUMOylation on CB formation was examined. We found that two types of global SUMOylation inhibition and expression of SUMO-deficient coilin mutants increased CB number but decreased CB size. Additionally, we saw via coimmunoprecipitation that a SUMO-deficient coilin mutant has altered interaction with Nopp140. This demonstrates increased mechanistic ties between CB formation and SUMOylation.
卡哈尔体（CBs）是无膜细胞器，其形成机制仍未完全明确。许多蛋白质参与了卡哈尔体的形成，包括Nopp140（NOLC1）、WRAP53和卷曲螺旋蛋白。卷曲螺旋蛋白在多个不同的赖氨酸残基上被类泛素小分子修饰物（SUMO）修饰。除了在卡哈尔体中积累外，卷曲螺旋蛋白也存在于核质中，其在核质中的作用仍在评估中。在这里，我们通过研究卷曲螺旋蛋白的SUMO化被破坏时其相互作用的变化，证明了一种新的卡哈尔体调节机制。研究了全局SUMO化抑制和卷曲螺旋蛋白SUMO化的靶向破坏对卡哈尔体形成的影响。我们发现，两种类型的全局SUMO化抑制以及SUMO缺陷型卷曲螺旋蛋白突变体的表达增加了卡哈尔体的数量，但减小了其大小。此外，我们通过免疫共沉淀发现，SUMO缺陷型卷曲螺旋蛋白突变体与Nopp140的相互作用发生了改变。这表明卡哈尔体形成与SUMO化之间的机制联系增强。
