A novel therapeutic approach for genetic diseases by introduction of suppressor tRNA.

The appearance of the premature translation termination codons (PTCs) in the transcript is the major cause of human genetic diseases. PTC-containing transcripts are rapidly degraded through nonsense-mediated decay (NMD) pathway. If such mRNA transcripts were translated in frame like normal transcripts, it would afford not only restoration of the level of full-length protein but also prevention of mRNA degradation by the NMD pathway. Here we describe a novel approach to read through PTC-containing mRNAs using suppressor tRNA that is introduced to cells by transfection. Luciferase reporter gene assay showed that nonsense and four-base codons were suppressed by the corresponding suppressor tRNAs derived from human tRNA(Ser). We also demonstrated that transfection of the suppressor tRNA to Ullrich disease fibroblasts, possessing a frameshift mutation in the collagen VI alpha2 gene, induced the upregulation of the collagen VI alpha2 mRNA and accumulation of the collagen VI protein. PTC suppression potentially provides a novel therapeutic means to rescue various PTC-related diseases.