Translational read-through-inducing drugs (TRIDs) promote read-through of nonsense mutations, placing them in the spotlight of current gene-based therapeutic research. Known TRIDs include clinically used aminoglycoside antibiotics like gentamicin and paromomycin, and several recently newly designed aminoglycosides like NB30 and NB54 as well as the unrelated chemical compound PTC124. Compared to gene addition approaches, TRIDs have significant advantages: 1) they do not act in a gene-specific manner, allowing treatment of diverse genetic conditions; 2) the size of the causative gene and restrictions in the vector capacity are no issue, and 3) the gene expression remains under endogenous control.
Here, we compare for the first time the relative efficacies of new generation aminoglycosides NB30, NB54, which were synthesized in our lab, and the chemical compound PTC124 on retinal toxicity and read-through efficacy of a nonsense mutation in the USH1C gene, which encodes the scaffold protein harmonin [1]. This mutation causes the human Usher syndrome, the most common form of inherited deaf-blindness. We quantify read-through efficacy of the TRIDs in cell culture and show the restoration of harmonin function. We do not observe significant differences in the read-through efficacy of the TRIDs in retinal cultures; however, we show an excellent biocompatibility in retinal cultures with read-through versus toxicity evidently superior for NB54 and PTC124. In addition, in vivo administration of NB54 and PTC124 induced recovery of the full-length harmonin a1 with the same efficacy. The high biocompatibilities combined with the sustained read-through efficacies of these drugs emphasize the potential of NB54 and PTC124 in treating nonsense mutation-based retinal disorders.
1. T.Goldmann, N. Overlack, F.Moller, V.Belakhov, M. van Wyk, T.Baasov, U.Wolfrum, K.Nagel-Wolfrum, EMBO Mol. Med., 4 (2012) 1-14.
