Pathological mechanism and antisense oligonucleotide-mediated rescue of a non-coding variant suppressing factor 9 RNA biogenesis leading to hemophilia B

by Simon Krooss, Sonja Werwitzke, Johannes Kopp, Alice Rovai, Dirk Varnholt, Amelie S. Wachs, Aurelie Goyenvalle, Annemieke Aarstma-Rus, Michael Ott, Andreas Tiede, J örg Langemeier, Jens Bohne Loss-of-function mutations in the human coagulation factor 9 (F9) gene lead to hemophilia B. Here, we dissected the consequences and the pathomechanism of a non-coding mutation (c.2545A>G) in theF9 3 ’ untranslated region. Using wild type and mutant factor IX (FIX) minigenes we revealed that the mutation leads to reducedF9 mRNA and FIX protein levels and to lower coagulation activity of cell culture supernatants. The phenotype could not be compensated by increased transcription. The pathomechanism comprises thede novo creation of a binding site for the spliceosomal component U1snRNP, which is able to suppress the nearbyF9 poly(A) site. This second, splicing-independent function of U1snRNP was discovered previously and blockade of U1snRNP restored mutantF9 mRNA expression. In addition, we explored the vice versa approach and masked the mutation by antisense oligonucleotides resulting in significantly increasedF9 mRNA expression and coagulation activity. This treatment may transform the moderate/severe hemophilia B into a mild or subclinical form in the patients. This antisense based strategy is applicable to other mutations in untranslated regions creating deleterious binding sites for cellular proteins.
Source: PLoS Genetics - Category: Genetics & Stem Cells Authors: Source Type: research