Distinct responses of COL17A1 nonsense variants to readthrough drugs and NOG as a novel enhancer in junctional epidermolysis bullosa.

Junctional epidermolysis bullosa (JEB) caused by COL17A1 pathogenic variants (JEB-C17) is characterized by skin fragility, chronic wounds, and an increased risk of squamous cell carcinoma. Approximately 20% of cases are caused by nonsense mutations, which induce premature termination codons (PTCs) resulting in truncated protein production and/or trigger mRNA degradation through nonsense-mediated decay (NMD) pathway. Different approaches have been suggested for nonsense mutation suppression including translational readthrough- inducing drugs (TRIDs) therapy, which is extensively examined in hereditary skin diseases due to relatively low costs for translation into the clinic. We evaluated a panel of TRIDs in patient-derived JEB-C17 keratinocytes carrying different COL17A1 nonsense variants. We observed variable responses to TRIDs across mutations. N-oxalylglycine (NOG) has been shown to reduce eRF1 hydroxylation and consequently inhibit NMD. We investigated NOG as an enhancer of aminoglycoside-mediated readthrough for JEB-C17. We previously developed a cocktail consisting of aminoglycosides, NMD inhibitors as enhancers of readthrough activity, and antioxidants that act as anti-inflammatory agents. In this study, we explored the effect of NOG as a readthrough enhancer in combination with TRIDs or TRID-cocktail. Our results support mutation-dependent TRID selection for further preclinical scientific investigations and highlight personalized therapeutic approaches as a key strategy for JEB-C17.