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