Department of Biotechnology, Jožef Stefan Institute, Ljubljana, 1000, Slovenia.
Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, Ljubljana, 1000, Slovenia.
Nat Commun. 2023 Sep 16;14(1):5764. doi: 10.1038/s41467-023-41511-3.
The expanded hexanucleotide GGGGCC repeat mutation in the C9orf72 gene is the main genetic cause of amyotrophic lateral sclerosis and frontotemporal dementia. Under one disease mechanism, sense and antisense transcripts of the repeat are predicted to bind various RNA-binding proteins, compromise their function and cause cytotoxicity. Here we identify phenylalanine-tRNA synthetase (FARS) subunit alpha (FARSA) as the main interactor of the CCCCGG antisense repeat RNA in cytosol. The aminoacylation of tRNA by FARS is inhibited by antisense RNA, leading to decreased levels of charged tRNA. Remarkably, this is associated with global reduction of phenylalanine incorporation in the proteome and decrease in expression of phenylalanine-rich proteins in cellular models and patient tissues. In conclusion, this study reveals functional inhibition of FARSA in the presence of antisense RNA repeats. Compromised aminoacylation of tRNA could lead to impairments in protein synthesis and further contribute to C9orf72 mutation-associated pathology.
C9orf72 基因中六核苷酸 GGGGCC 重复扩增突变是肌萎缩侧索硬化症和额颞叶痴呆的主要遗传原因。在一个疾病机制下，重复序列的正义和反义转录本被预测与各种 RNA 结合蛋白结合，破坏其功能并导致细胞毒性。在这里，我们鉴定出苯丙氨酸 tRNA 合成酶 (FARS) 亚基 α (FARSA) 是细胞质中 CCCCGG 反义重复 RNA 的主要相互作用蛋白。FARS 对 tRNA 的氨酰化被反义 RNA 抑制，导致带电荷的 tRNA 水平降低。值得注意的是，这与蛋白质组中苯丙氨酸掺入的整体减少以及细胞模型和患者组织中富含苯丙氨酸的蛋白质表达的减少有关。总之，这项研究揭示了反义 RNA 重复存在时 FARSA 的功能抑制。tRNA 的氨酰化受损可能导致蛋白质合成受损，并进一步导致 C9orf72 突变相关的病理学。
