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Tseng YJ, Sandwith SN, Green KM, Chambers AE, Krans A, Raimer HM, Sharlow ME, Reisinger MA, Richardson AE, Routh ED, Smaldino MA, Wang YH, Vaughn JP, Todd PK, Smaldino PJ. The RNA helicase DHX36-G4R1 modulates C9orf72 GGGGCC hexanucleotide repeat-associated translation. J Biol Chem 2021; 297:100914. [PMID: 34174288 PMCID: PMC8326427 DOI: 10.1016/j.jbc.2021.100914] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 06/02/2021] [Accepted: 06/22/2021] [Indexed: 12/26/2022] Open
Abstract
GGGGCC (G4C2) hexanucleotide repeat expansions in the endosomal trafficking gene C9orf72 are the most common genetic cause of ALS and frontotemporal dementia. Repeat-associated non-AUG (RAN) translation of this expansion through near-cognate initiation codon usage and internal ribosomal entry generates toxic proteins that accumulate in patients' brains and contribute to disease pathogenesis. The helicase protein DEAH-box helicase 36 (DHX36–G4R1) plays active roles in RNA and DNA G-quadruplex (G4) resolution in cells. As G4C2 repeats are known to form G4 structures in vitro, we sought to determine the impact of manipulating DHX36 expression on repeat transcription and RAN translation. Using a series of luciferase reporter assays both in cells and in vitro, we found that DHX36 depletion suppresses RAN translation in a repeat length–dependent manner, whereas overexpression of DHX36 enhances RAN translation from G4C2 reporter RNAs. Moreover, upregulation of RAN translation that is typically triggered by integrated stress response activation is prevented by loss of DHX36. These results suggest that DHX36 is active in regulating G4C2 repeat translation, providing potential implications for therapeutic development in nucleotide repeat expansion disorders.
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Affiliation(s)
- Yi-Ju Tseng
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA; Cellular and Molecular Biology Graduate Program, University of Michigan, Ann Arbor, Michigan, USA
| | - Siara N Sandwith
- Department of Biology, Ball State University, Muncie, Indiana, USA
| | - Katelyn M Green
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Amy Krans
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Heather M Raimer
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA
| | | | | | | | - Eric D Routh
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | - Yuh-Hwa Wang
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, Virginia, USA
| | - James P Vaughn
- Division of Cancer Biology, NanoMedica LLC, Winston-Salem, North Carolina, USA
| | - Peter K Todd
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA; Department of Neurology, Ann Arbor VA Medical Center, Ann Arbor, Michigan, USA.
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