Cardiovascular Research Institute, University of California, San Francisco, CA 94143.
Weill Institute for Neurosciences, University of California, San Francisco, CA 94143.
Proc Natl Acad Sci U S A. 2024 Jul 30;121(31):e2220020121. doi: 10.1073/pnas.2220020121. Epub 2024 Jul 23.
Expansion of intronic GGGGCC repeats in the gene causes amyotrophic lateral sclerosis (ALS) and frontotemporal dementia. Transcription of the expanded repeats results in the formation of RNA-containing nuclear foci and altered RNA metabolism. In addition, repeat-associated non-AUG (RAN) translation of the expanded GGGGCC-repeat sequence results in the production of highly toxic dipeptide-repeat (DPR) proteins. GGGGCC repeat-containing transcripts form G-quadruplexes, which are associated with formation of RNA foci and RAN translation. Zfp106, an RNA-binding protein essential for motor neuron survival in mice, suppresses neurotoxicity in a model of ALS. Here, we show that Zfp106 inhibits formation of RNA foci and significantly reduces RAN translation caused by GGGGCC repeats in cultured mammalian cells, and we demonstrate that Zfp106 coexpression reduces the levels of DPRs in patient-derived cells. Further, we show that Zfp106 binds to RNA G-quadruplexes and causes a conformational change in the G-quadruplex structure formed by GGGGCC repeats. Together, these data demonstrate that Zfp106 suppresses the formation of RNA foci and DPRs caused by GGGGCC repeats and suggest that the G-quadruplex RNA-binding function of Zfp106 contributes to its suppression of GGGGCC repeat-mediated cytotoxicity.
基因中的内含子 GGGGCC 重复扩展会导致肌萎缩侧索硬化症（ALS）和额颞叶痴呆。扩展重复的转录导致含有 RNA 的核焦点的形成和改变的 RNA 代谢。此外，扩展的 GGGGCC 重复序列的重复相关非 AUG（RAN）翻译导致产生高度毒性的二肽重复（DPR）蛋白。含有 GGGGCC 重复的转录物形成 G-四链体，与 RNA 焦点的形成和 RAN 翻译有关。Zfp106 是一种在小鼠中对运动神经元存活至关重要的 RNA 结合蛋白，它可以抑制 ALS 模型中的神经毒性。在这里，我们表明 Zfp106 抑制了培养的哺乳动物细胞中 GGGGCC 重复引起的 RNA 焦点的形成，并显著降低了 RAN 翻译，并且我们证明 Zfp106 的共表达降低了患者来源细胞中 DPR 的水平。此外，我们表明 Zfp106 结合 RNA G-四链体并导致 GGGGCC 重复形成的 G-四链体结构发生构象变化。总之，这些数据表明 Zfp106 抑制了 GGGGCC 重复引起的 RNA 焦点和 DPR 的形成，并表明 Zfp106 的 G-四链体 RNA 结合功能有助于其抑制 GGGGCC 重复介导的细胞毒性。
