Inhaled Suppressor tRNA Therapy Restores Gene Function in Cystic Fibrosis Models
- Researchers at the University of Toronto have developed a next-generation RNA therapeutic strategy designed to treat genetic disorders caused by nonsense mutations, according to findings reported in the...
- Nonsense mutations introduce premature termination codons into messenger RNA, causing cellular protein production to halt early and resulting in truncated or entirely absent proteins.
- The investigators tested the therapeutic approach across bronchial epithelial cells, mouse models, and patient-derived cystic fibrosis organoids.
Researchers at the University of Toronto have developed a next-generation RNA therapeutic strategy designed to treat genetic disorders caused by nonsense mutations, according to findings reported in the journal Science. Led by Bowen Li, an associate professor in the Leslie Dan Faculty of Pharmacy, the research team successfully combined chemically enhanced suppressor transfer RNAs with a lung-targeted delivery system to restore production of a critical protein in models of cystic fibrosis.
Targeting Nonsense Mutations at the Cellular Level
Nonsense mutations introduce premature termination codons into messenger RNA, causing cellular protein production to halt early and resulting in truncated or entirely absent proteins. These specific mutations account for approximately 11% of human genetic disorders. To overcome this biological roadblock, the University of Toronto team engineered suppressor transfer tRNAs to help cells read through premature stop signals and complete the synthesis of full-length proteins.
Testing Across Bronchial Cells and Organoids
The investigators tested the therapeutic approach across bronchial epithelial cells, mouse models, and patient-derived cystic fibrosis organoids. The chemical modifications successfully increased the readthrough of premature termination codons and tRNA aminoacylation while prolonging functional activity and reducing innate immune activation. Ultimately, the intervention restored CFTR protein production and function across all tested models.
Breaking Past Historical Hurdles in RNA Delivery
The clinical potential of suppressor tRNAs has been limited by inefficient readthrough, immunogenicity, and difficulty in delivering them into the body. Gene-editing approaches often face challenges related to delivery, immunogenicity, and off-target effects, while pharmacological readthrough agents have shown limited efficacy or considerable toxicity.
Inhalation Delivery via Lipid Nanoparticles
To address these obstacles, the research team engineered specialized lipid nanoparticles tailored for delivery into the lungs via inhalation. Bowen Li and colleagues noted that the strategy lays the groundwork for a new class of drugs capable of treating a broad spectrum of genetic diseases through a common therapeutic mechanism, rather than requiring individual gene therapies for rare mutations that affect only small patient populations. Furthermore, the data showed that the suppressor tRNA approach can be combined with existing cystic fibrosis medications, opening the door for potential combination therapies.