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Elife. 2016 Sep 13;5. pii: e17820. doi: 10.7554/eLife.17820.

The C9ORF72 GGGGCC expansion forms RNA G-quadruplex inclusions and sequesters hnRNP H to disrupt splicing in ALS brains.

Author information

1
Department of Biological Sciences, Columbia University, New York, United States.
2
Department of Neurology, Columbia University Medical Center, New York, United States.

Abstract

An expanded GGGGCC hexanucleotide in C9ORF72 (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.

KEYWORDS:

RNA structure; amyotrophic lateral sclerosis; biochemistry; disease mechanism; human; human biology; medicine

PMID:
27623008
PMCID:
PMC5050020
DOI:
10.7554/eLife.17820
[Indexed for MEDLINE]
Free PMC Article

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