Identification of a PRPF4 loss-of-function variant that abrogates U4/U6.U5 tri-snRNP integration and is associated with retinitis pigmentosa

PLoS One. 2014 Nov 10;9(11):e111754. doi: 10.1371/journal.pone.0111754. eCollection 2014.

Abstract

Pre-mRNA splicing by the spliceosome is an essential step in the maturation of nearly all human mRNAs. Mutations in six spliceosomal proteins, PRPF3, PRPF4, PRPF6, PRPF8, PRPF31 and SNRNP200, cause retinitis pigmentosa (RP), a disease characterized by progressive photoreceptor degeneration. All splicing factors linked to RP are constituents of the U4/U6.U5 tri-snRNP subunit of the spliceosome, suggesting that the compromised function of this particle may lead to RP. Here, we report the identification of the p.R192H variant of the tri-snRNP factor PRPF4 in a patient with RP. The mutation affects a highly conserved arginine residue that is crucial for PRPF4 function. Introduction of a corresponding mutation into the zebrafish homolog of PRPF4 resulted in a complete loss of function in vivo. A series of biochemical experiments suggested that p.R192H disrupts the binding interface between PRPF4 and its interactor PRPF3. This interferes with the ability of PRPF4 to integrate into the tri-snRNP, as shown in a human cell line and in zebrafish embryos. These data suggest that the p.R192H variant of PRPF4 represents a functional null allele. The resulting haploinsufficiency of PRPF4 compromises the function of the tri-snRNP, reinforcing the notion that this spliceosomal particle is of crucial importance in the physiology of the retina.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Blotting, Western
  • Embryo, Nonmammalian / metabolism
  • Gangliosides / metabolism
  • Gene Components
  • HEK293 Cells
  • Humans
  • Molecular Sequence Data
  • Mutation, Missense / genetics*
  • Nuclear Proteins / metabolism
  • Pedigree
  • Retinitis Pigmentosa / genetics*
  • Ribonucleoprotein, U4-U6 Small Nuclear / genetics*
  • Ribonucleoprotein, U4-U6 Small Nuclear / metabolism
  • Sequence Analysis, DNA
  • Spliceosomes / genetics*
  • Spliceosomes / metabolism
  • Zebrafish

Substances

  • 7-O-acetyl-GD3 ganglioside
  • Gangliosides
  • Nuclear Proteins
  • PRPF3 protein, human
  • PRPF4 protein, human
  • Ribonucleoprotein, U4-U6 Small Nuclear

Grant support

This work was supported by German Research Foundation (DFG) grants to U. Fischer and an Academic Research Fund (AcRF) grant (T207B3107) of the Ministry of Education, Singapore to C. Winkler. B. Linder and A. Hirmer received fellowships from the German ProRetina Foundation and the Graduiertenkolleg GK 1048, respectively. This publication was funded by the German Research Foundation (DFG) and the University of Wuerzburg in the funding programme Open Access Publishing. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.