Use of 2,6-diaminopurine as a highly potent corrector of UGA nonsense mutations in recessive dystrophic epidermolysis bullosa.

Summary: Abstract Body: Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a debilitating blistering skin disease caused by mutations in the gene encoding type VII collagen (C7), a crucial component of the dermal-epidermal junction. Among patients with RDEB, approximately 25% possess nonsense mutations that introduce premature termination codons (PTCs), leading to impaired protein production. Our prior research demonstrated that gentamicin, administered topically or intravenously, could facilitate PTC readthrough and promote the production of functional C7 in patients with RDEB. However, the extended use of gentamicin is restricted by its toxicity, including nephrotoxicity and ototoxicity, necessitating the exploration of safer and more effective alternatives. Recent efforts have centered on identifying compounds with enhanced PTC readthrough efficiency and reduced toxicity. Among these, 2,6-diaminopurine (DAP) has emerged as a promising candidate, exhibiting the ability to promote efficient readthrough of UGA premature stop codons in various in vitro and in vivo disease models. In the current study, we sought to evaluate whether DAP could induce PTC readthrough and restore C7 expression in primary fibroblasts and keratinocytes derived from RDEB patients harboring different nonsense mutations. Our findings revealed that DAP significantly increased the synthesis of C7 in RDEB cells in a dose-dependent manner, achieving superior efficacy compared to high-dose gentamicin. Mechanistically, DAP-induced PTC readthrough and C7 production in RDEB cells are mediated by increasing mRNA stability. Additionally, the restored C7 reversed the abnormal hypermotility characteristic of RDEB cells, indicating functional recovery. Importantly, in RDEB skin equivalents, DAP-induced C7 localized accurately to the dermal-epidermal junction. These results suggest that DAP holds significant potential as a novel, safe, and effective treatment for RDEB and other genetic disorders caused by nonsense mutations. Kathleen L. Miao¹, Brandon Levian¹, Ryan Huynh¹, Aryana Nazem¹, Yingping Hou¹, Mei Chen¹ 1. Dermatology, University of Southern California Keck School of Medicine, Los Angeles, CA, United States. Translational Studies: Preclinical