In biomedicine some target proteins are considered to be undruggable. These targets can be modulated by adapting ribosomal gene expression. We have tested this hypothesis in severe junctional epidermolysis bullosa (sJEB), in which homozygosity for premature termination codon (PTC) mutations in skin anchor protein LAMB3 is pathogenic. RiboScreen® technology generates specialized ribosomes that ignore the PTC signal in LAMB3mRNA. Using RiboScreen®, we first assayed yeast ribosomal variant strains with functional depletions of ribosomal proteins in order to identify a first in class target ribosomal protein, rpL35, for a repair of LAMB3PTC production. Modulating rpl35 function triggers the ribosome to increase production levels of full-length Lamb3 protein harboring the PTC mutation. Next, using RiboScreen®, we identified candidate ligands, the clinically developed drugs artesunate and atazanavir, for both yeast and human rpL35. Binding of these two molecules to human rpL35 was tested in vitro using solution nuclear magnetic resonance (NMR) spectroscopy, and both drugs target rpL35 with overlapping binding sites at an N-terminal rpL35 domain that is accessible on the assembled ribosome. Next, using a yeast based semi-automated dual luciferase protein expression assay, RiboScreen® showed biological activity of artesunate and atazanavir in promoting increased production levels of full-length Lamb3PTC protein. Finally, using a human cell line engineered for homozygosity of LAMB3R635XPTC, the biological activity of artesunate was confirmed in a human keratinocyte cell model.

ESDR158 - Targeting gene expression at the ribosome: Correction of the mutation LAMB3R635X in Epidermolysis bullosa

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING