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.
Distinct brain transcriptome profiles in c9orf72-associated and sporadic ALSPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE67196).
Illumina mRNA-Seq of control and hnRNP H knockdown in 293T cellsPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE16642).
Analysis and design of RNA sequencing experiments for identifying mRNA isoform regulationPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE23694).
- Erin G Conlon
- James L Manley
- James L Manley
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Human subjects: Informed consent, including consent to publish, was obtained for human derived fibroblast and astrocyte lines used in this study by the IRB of Columbia University under protocols #AAAB0483 and #AAAC1257. For fibroblasts, written consent was given by the patients, and for astrocytes, written consent was given by the families of the deceased. Human tissue was donated for research purposes by the next of kin.
- Douglas L Black, University of California, Los Angeles, United States
- Received: May 13, 2016
- Accepted: September 8, 2016
- Accepted Manuscript published: September 13, 2016 (version 1)
- Accepted Manuscript updated: September 14, 2016 (version 2)
- Accepted Manuscript updated: September 17, 2016 (version 3)
- Accepted Manuscript updated: September 21, 2016 (version 4)
- Version of Record published: October 4, 2016 (version 5)
- Version of Record updated: October 7, 2016 (version 6)
- Version of Record updated: October 10, 2016 (version 7)
© 2016, Conlon et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.