Modulation of prion protein expression through cryptic splice site manipulation

J Biol Chem. 2024 Aug;300(8):107560. doi: 10.1016/j.jbc.2024.107560. Epub 2024 Jul 11.

Abstract

Lowering expression of prion protein (PrP) is a well-validated therapeutic strategy in prion disease, but additional modalities are urgently needed. In other diseases, small molecules have proven capable of modulating pre-mRNA splicing, sometimes by forcing inclusion of cryptic exons that reduce gene expression. Here, we characterize a cryptic exon located in human PRNP's sole intron and evaluate its potential to reduce PrP expression through incorporation into the 5' untranslated region. This exon is homologous to exon 2 in nonprimate species but contains a start codon that would yield an upstream open reading frame with a stop codon prior to a splice site if included in PRNP mRNA, potentially downregulating PrP expression through translational repression or nonsense-mediated decay. We establish a minigene transfection system and test a panel of splice site alterations, identifying mutants that reduce PrP expression by as much as 78%. Our findings nominate a new therapeutic target for lowering PrP.

Keywords: cryptic exon; minigene; prion protein; splice modulation; upstream open reading frame.

MeSH terms

  • 5' Untranslated Regions
  • Animals
  • Exons*
  • Gene Expression Regulation
  • Humans
  • Introns
  • Prion Diseases / genetics
  • Prion Diseases / metabolism
  • Prion Proteins* / genetics
  • Prion Proteins* / metabolism
  • Prions / genetics
  • Prions / metabolism
  • RNA Splice Sites*
  • RNA Splicing

Substances

  • RNA Splice Sites
  • Prion Proteins
  • PRNP protein, human
  • Prions
  • 5' Untranslated Regions