Ribosome profiling reveals novel regulation of C9ORF72 GGGGCC repeat-containing RNA translation
- Heleen M. van ‘t Spijker1,4,
- Emily E. Stackpole1,4,
- Sandra Almeida2,4,
- Olga Katsara3,
- Botao Liu1,
- Kuang Shen1,
- Robert J. Schneider3,
- Fen-Biao Gao2 and
- Joel D. Richter1
- 1Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
- 2Department of Neurology, University of Massachusetts Chan Medical School, Worcester, Massachusetts 01605, USA
- 3Department of Microbiology, New York University School of Medicine, New York, New York 10016, USA
- Corresponding authors: Joel.richter{at}umassmed.edu, Fen-biao.gao{at}umassmed.edu
-
↵4 These authors contributed equally to this work.
Abstract
GGGGCC (G4C2) repeat expansion in the first intron of C9ORF72 causes amyotrophic lateral sclerosis and frontotemporal dementia. Repeat-containing RNA is translated into dipeptide repeat (DPR) proteins, some of which are neurotoxic. Using dynamic ribosome profiling, we identified three translation initiation sites in the intron upstream of (G4C2) repeats; these sites are detected irrespective of the presence or absence of the repeats. During translocation, ribosomes appear to be stalled on the repeats. An AUG in the preceding C9ORF72 exon initiates a uORF that inhibits downstream translation. Polysome isolation indicates that unspliced (G4C2) repeat-containing RNA is a substrate for DPR protein synthesis. (G4C2) repeat-containing RNA translation is 5′ cap-independent but inhibited by the initiation factor DAP5, suggesting an interplay with uORF function. These results define novel translational mechanisms of expanded (G4C2) repeat-containing RNA in disease.
Keywords
- Received August 24, 2021.
- Accepted October 31, 2021.
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