Molecular Basis and Therapeutic Strategies to Rescue Factor IX Variants That Affect Splicing and Protein Function

• Published in: PLoS genetics Vol. 12; no. 5; p. e1006082
• Main Authors: Tajnik, Mojca, Rogalska, Malgorzata Ewa, Bussani, Erica, Barbon, Elena, Balestra, Dario, Pinotti, Mirko, Pagani, Franco
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26-05-2016; Public Library of Science (PLoS)
• Subjects: Biology and Life Sciences; Blood Coagulation Disorders - genetics; Blood Coagulation Disorders - pathology; Cell Culture Techniques; Exons - genetics; Factor IX; Factor IX - genetics; Gene mutation; Genes; Genetic aspects; Genetic research; Genetic Vectors; Health aspects; Hemophilia; Humans; Medicine and Health Sciences; Molecular genetics; Mutation; Plasmids; Proteins; Ribonucleoproteins, Small Nuclear - genetics; RNA Precursors - genetics; RNA Splice Sites - genetics; RNA splicing; RNA Splicing - genetics; Rodents; Serine-Arginine Splicing Factors - genetics; Spectrum analysis; Transfection; Varieties
• ISSN: 1553-7404; 1553-7390; 1553-7404
• DOI: 10.1371/journal.pgen.1006082

Mutations that result in amino acid changes can affect both pre-mRNA splicing and protein function. Understanding the combined effect is essential for correct diagnosis and for establishing the most appropriate therapeutic strategy at the molecular level. We have identified a series of disease-causing splicing mutations in coagulation factor IX (FIX) exon 5 that are completely recovered by a modified U1snRNP particle, through an SRSF2-dependent enhancement mechanism. We discovered that synonymous mutations and missense substitutions associated to a partial FIX secretion defect represent targets for this therapy as the resulting spliced-corrected proteins maintains normal FIX coagulant specific activity. Thus, splicing and protein alterations contribute to define at the molecular level the disease-causing effect of a number of exonic mutations in coagulation FIX exon 5. In addition, our results have a significant impact in the development of splicing-switching therapies in particular for mutations that affect both splicing and protein function where increasing the amount of a correctly spliced protein can circumvent the basic functional defects.