By Anna Dutton
DNA mutations can sometimes lead to the production of faulty proteins in the cells of those who are suffering from genetic diseases. New methods are being investigated to see whether the cells can be altered to produce the correct number of proteins, thereby stopping the faulty gene being passed on.
In each cell of the human body, the three-letter DNA sequence that creates proteins is called a codon. Sometimes, these proteins stop reproducing before a cell has the correct number of proteins. For example, a cell should be 100 amino acids long, but the faulty gene can stop producing proteins after 15 amino acids are produced. This lack of amino acids renders the cell inactive an these ‘nonsense mutations’ cause 10% of genetic diseases.
New research has come to light suggesting there may be a way to improve faulty cells. In the 1980’s, a method was suggested that investigated TRNA’s. These molecules recognise codons while a protein is being produced, and then match the right amino acid to them. It is now possible to make artificial TRNA’s that recognise a premature stop codon, and instead of terminating the protein production, they add the amino acid required to make the cell useful.
Artificial TRNA’s are smaller so treatments could be developed quicker. Once these TRNA’s are inside a cell, they compete with faulty proteins that bind together to stop the production of a codon. Instead of halting the creation of proteins, the TRNA’s endorse it. Unfortunately, this method cannot fix every degenerate gene, but it could help just enough to make a difference.
Research into this method has shown some promising results. At the University of Porto in Portugal in 2014, Carla Oliveira and her team restored the production of healthy proteins in a cell that caused hereditary breast and stomach cancers. The only option for these people currently was to have either their stomach or breasts removed, so the results are promising for those already suffering.
Christopher Ahern at Iowa University trialled the same solution, but for patients with cystic fibrosis. In their experiment, Ahern’s team carried out the same test as Oliveira’s team, and found that with further experiments this approach could offer an alternative to drugs and gene therapy cystic fibrosis patients. Ahern believes that one day cystic fibrosis can be cured if the cells ‘… could recapitulate in the lungs’ where they are most needed.
There is some scepticism surrounding this method as the TRNA’s could interfere with healthy cells. But, evidence from other research implies they should be safe as ‘… TRNA’s that are targeted to stop codons is tolerated in animals’ assures Jason Chin of Cambridge University. Further tests would be required to ascertain the effect on human cells, but the outlook is hopeful.
In summary, the use of TRNA’s is an exciting new development toward curing genetic diseases. Despite necessary further tests, the future is a little brighter for those who are already suffering.