Development of allele-specific therapeutic siRNA in Meesmann epithelial corneal dystrophy

• Published in: PloS one 2011-12, Vol.6 (12), p.e28582-e28582
• Main Authors: Liao, Haihui, Irvine, Alan D, Macewen, Caroline J, Weed, Kathryn H, Porter, Louise, Corden, Laura D, Gibson, A Bethany, Moore, Jonathan E, Smith, Frances J D, McLean, W H Irwin, Moore, C B Tara
• Format: Article
• Language: English
• Subjects: Acuity; Alleles; Base Sequence; Biology; Care and treatment; Cell culture; Cells, Cultured; Confidence limits; Cornea; Corneal dystrophy; Corneal Dystrophy, Juvenile Epithelial of Meesmann - genetics; Corneal Dystrophy, Juvenile Epithelial of Meesmann - therapy; Dentistry; Dystrophy; Enzymes; Epithelium; Eye; Eye diseases; Feasibility studies; Filaments; Fragility; Gene expression; Gene mutation; Gene Silencing; Gene Transfer Techniques; Genetic aspects; Genotype & phenotype; Health aspects; Hereditary diseases; Hospitals; Humans; Inhibitors; Irritation; Keratin; Keratins; Keratins - chemistry; Life sciences; Medical research; Medicine; Missense mutation; Molecular Sequence Data; Mutant Proteins - chemistry; Mutation; Nursing; Ophthalmology; Protein Structure, Quaternary; Proteins; RNA, Small Interfering - genetics; RNA, Small Interfering - therapeutic use; Scars; siRNA; Surgery; Topography; Transfection; Visual acuity
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0028582

Meesmann epithelial corneal dystrophy (MECD) is an inherited eye disorder caused by dominant-negative mutations in either keratins K3 or K12, leading to mechanical fragility of the anterior corneal epithelium, the outermost covering of the eye. Typically, patients suffer from lifelong irritation of the eye and/or photophobia but rarely lose visual acuity; however, some individuals are severely affected, with corneal scarring requiring transplant surgery. At present no treatment exists which addresses the underlying pathology of corneal dystrophy. The aim of this study was to design and assess the efficacy and potency of an allele-specific siRNA approach as a future treatment for MECD. We studied a family with a consistently severe phenotype where all affected persons were shown to carry heterozygous missense mutation Leu132Pro in the KRT12 gene. Using a cell-culture assay of keratin filament formation, mutation Leu132Pro was shown to be significantly more disruptive than the most common mutation, Arg135Thr, which is associated with typical, mild MECD. A siRNA sequence walk identified a number of potent inhibitors for the mutant allele, which had no appreciable effect on wild-type K12. The most specific and potent inhibitors were shown to completely block mutant K12 protein expression with negligible effect on wild-type K12 or other closely related keratins. Cells transfected with wild-type K12-EGFP construct show a predominantly normal keratin filament formation with only 5% aggregate formation, while transfection with mutant K12-EGFP construct resulted in a significantly higher percentage of keratin aggregates (41.75%; p