Premature transcription termination at the expanded GAA repeats and aberrant alternative polyadenylation contributes to the Frataxin transcriptional deficit in Friedreich's ataxia

Yanjie Li, Jixue Li, Jun Wang, Siyuan Zhang, Keith Giles, Thazha P. Prakash, Frank Rigo, Jill S. Napierala, Marek Napierala

Research output: Contribution to journalArticlepeer-review

Abstract

Frataxin deficiency in Friedreich's ataxia results from transcriptional downregulation of the FXN gene caused by expansion of the intronic trinucleotide guanine-adenine-adenine (GAA) repeats. We used multiple transcriptomic approaches to determine the molecular mechanism of transcription inhibition caused by long GAAs. We uncovered that transcription of FXN in patient cells is prematurely terminated upstream of the expanded repeats leading to the formation of a novel, truncated and stable RNA. This FXN early terminated transcript (FXN-ett) undergoes alternative, non-productive splicing and does not contribute to the synthesis of functional frataxin. The level the FXN-ett RNA directly correlates with the length of the longer of the two expanded GAA tracts. Targeting GAAs with antisense oligonucleotides or excision of the repeats eliminates the transcription impediment, diminishes expression of the aberrant FXN-ett, while increasing levels of FXN mRNA and frataxin. Non-productive transcription may represent a common phenomenon and attractive therapeutic target in diseases caused by repeat-mediated transcription aberrations.

Original languageEnglish (US)
Pages (from-to)3539-3557
Number of pages19
JournalHuman molecular genetics
Volume31
Issue number20
DOIs
StatePublished - Oct 10 2022

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Genetics(clinical)

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