Some mutations in the CFTR gene, known as nonsense mutations, cause CFTR protein production to stop prematurely. The cell interprets the mutation as a signal to stop and therefore produces an incomplete, non-functional protein. This can be an obstacle for available therapies: CFTR modulators act on the CFTR protein and, in the presence of some nonsense mutations, too little protein may be produced for these drugs to work effectively.

ACE-tRNAs represent a possible strategy to overcome this obstacle. They are engineered RNA molecules designed to help the cell bypass the premature stop signal and continue translating the genetic instructions. In this way, protein production can continue to the end, with the aiming to produce a complete CFTR protein and partially restoring its function. Compared with other approaches (such as Ataluren or ELX-02), ACE-tRNAs are designed to act with high precision. Laboratory and animal studies have already shown promising results, including the restoration of CFTR function.

The challenge now is to find an effective way to deliver ACE-tRNAs to airway cells, where they need to exert their effect.

To address this challenge, the project uses three innovative tools. i) DNA picovectors are tiny “containers” carrying genetic instructions: they deliver to cells the information needed to produce ACE-tRNAs. ii) Nanobodies, which are small antibody fragments, could help direct the picovectors towards target cells in the lungs, acting like a sort of molecular navigation system. iii) Finally, the “Stop-Go-Glow” animal model allows researchers to visualize by fluorescence when the stop signal has been successfully bypassed, providing a way to assess where and how effectively the treatment works.

The researchers will investigate whether this strategy can reach airway cells and bypass nonsense mutations. Experiments will initially be conducted using the “Stop-Go-Glow” model and subsequently in a cystic fibrosis animal model carrying the G542X stop mutation. In parallel, new nanobodies will be studied to improve the precision with which lung cells can be targeted.

If the results are positive, this research could contribute to the development of a new therapeutic strategy for people with cystic fibrosis who carry nonsense mutations. Moreover, since the same type of mutation is responsible for numerous genetic diseases, ACE-tRNA technology could potentially have applications in other conditions in the future.