Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Malaya Pirogovskaya, 1a, 119435 Moscow, Russia.
Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Lopukhin Federal Research and Clinical Center of Physical-Chemical Medicine of Federal Medical Biological Agency, Malaya Pirogovskaya, 1a, 119435 Moscow, Russia.
Molecules. 2024 Sep 14;29(18):4369. doi: 10.3390/molecules29184369.
Abnormal intracellular phase transitions in mutant hnRNP A1 may underlie the development of several neurodegenerative diseases. The risk of these diseases increases upon repeat expansion and the accumulation of the corresponding G-quadruplex (G4)-forming RNA, but the link between this RNA and the disruption of hnRNP A1 homeostasis has not been fully explored so far. Our aim was to clarify the mutual effects of hnRNP A1 and C9Orf72 G4 in vitro. Using various optical methods and atomic force microscopy, we investigated the influence of the G4 on the formation of cross-beta fibrils by the mutant prion-like domain (PLD) of hnRNP A1 and on the co-separation of the non-mutant protein with a typical SR-rich fragment of a splicing factor (SRSF), which normally drives the assembly of nuclear speckles. The G4 was shown to act in a holdase-like manner, i.e., to restrict the fibrillation of the hnRNP A1 PLD, presumably through interactions with the PLD-flanking RGG motif. These interactions resulted in partial unwinding of the G4, suggesting a helicase-like activity of hnRNP A1 RGG. At the same time, the G4 was shown to disrupt hnRNP A1 co-separation with SRSF, suggesting its possible contribution to pathology through interference with splicing regulation.
异常的细胞内相变在突变 hnRNP A1 中可能是几种神经退行性疾病发展的基础。这些疾病的风险会随着重复扩展和相应 G-四链体 (G4) 形成 RNA 的积累而增加，但到目前为止，这种 RNA 与 hnRNP A1 动态平衡破坏之间的联系尚未得到充分探索。我们的目的是阐明体外 hnRNP A1 和 C9Orf72 G4 之间的相互作用。使用各种光学方法和原子力显微镜，我们研究了 G4 对突变体朊病毒样结构域 (PLD) 的 hnRNP A1 形成交叉-β纤维以及非突变蛋白与剪接因子 (SRSF) 的典型富含 SR 片段的共分离的影响，该片段通常驱动核斑点的组装。G4 表现出类似热休克蛋白的作用，即限制 hnRNP A1 PLD 的纤维化，推测这是通过与 PLD 侧翼 RGG 基序的相互作用实现的。这些相互作用导致 G4 的部分解旋，这表明 hnRNP A1 RGG 具有解旋酶样活性。与此同时，G4 被证明破坏了 hnRNP A1 与 SRSF 的共分离，这表明它可能通过干扰剪接调节而对病理学产生影响。
