Aminoglycoside-Induced Premature Stop Codon Read-Through of Mucopolysaccharidosis Type I Patient Q70X and W402X Mutations in Cultured Cells.

The premature stop codon mutations, Q70X and W402X, are the most common α-L-iduronidase gene (IDUA) mutations in mucopolysaccharidosis type I (MPS I) patients. Read-through drugs have been used to suppress premature stop codons, and this can potentially be used to treat patients who have this type of mutation. We examined the effects of aminoglycoside treatment on the IDUA mutations Q70X and W402X in cultured cells and show that 4,5-disubstituted aminoglycosides induced more read-through for the W402X mutation, while 4,6-disubstituted aminoglycosides promoted more read-through for the Q70X mutation: lividomycin (4,5-disubstituted) induced a 7.8-fold increase in α-L-iduronidase enzyme activity for the W402X mutation; NB54 (4,5-disubstituted) induced a 3.7 fold increase in the amount of α-L-iduronidase enzyme activity for the W402X mutation, but had less effect on the Q70X mutation, whereas gentamicin (4,6-disubstituted) had the reverse effect on read-through for both mutations. The predicted mRNA secondary structural changes for both mutations were markedly different, which may explain these different effects on read-through for these two premature stop codons.