Conlon Erin G, Lu Lei, Sharma Aarti, Yamazaki Takashi, Tang Timothy, Shneider Neil A, Manley James L
Department of Biological Sciences, Columbia University, New York, United States.
Department of Neurology, Columbia University Medical Center, New York, United States.
Elife. 2016 Sep 13;5:e17820. doi: 10.7554/eLife.17820.
An expanded GGGGCC hexanucleotide in (C9) is the most frequent known cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). It has been proposed that expanded transcripts adopt G-quadruplex (G-Q) structures and associate with proteins, but whether this occurs and contributes to disease is unknown. Here we show first that the protein that predominantly associates with GGGGCC repeat RNA in vitro is the splicing factor hnRNP H, and that this interaction is linked to G-Q formation. We then show that G-Q RNA foci are more abundant in C9 ALS patient fibroblasts and astrocytes compared to those without the expansion, and more frequently colocalize with hnRNP H. Importantly, we demonstrate dysregulated splicing of multiple known hnRNP H-target transcripts in C9 patient brains, which correlates with elevated insoluble hnRNP H/G-Q aggregates. Together, our data implicate C9 expansion-mediated sequestration of hnRNP H as a significant contributor to neurodegeneration in C9 ALS/FTD.
（C9）中扩展的GGGGCC六核苷酸是肌萎缩侧索硬化症（ALS）和额颞叶痴呆（FTD）最常见的已知病因。有人提出，扩展的转录本会形成G-四链体（G-Q）结构并与蛋白质结合，但这种情况是否发生以及是否导致疾病尚不清楚。在这里，我们首先表明，在体外与GGGGCC重复RNA主要结合的蛋白质是剪接因子hnRNP H，并且这种相互作用与G-Q形成有关。然后我们表明，与未发生扩展的细胞相比，G-Q RNA病灶在C9 ALS患者的成纤维细胞和星形胶质细胞中更为丰富，并且更频繁地与hnRNP H共定位。重要的是，我们证明了C9患者大脑中多个已知的hnRNP H靶转录本的剪接失调，这与不溶性hnRNP H/G-Q聚集体的增加相关。总之，我们的数据表明，C9扩展介导的hnRNP H隔离是C9 ALS/FTD神经退行性变的重要原因。
