The slowdown in the transport of drugs at RNA inside cells can strengthen the effectiveness of genetic diseases

A recent study involving researchers from the University of Basel reveals that the slowdown in intracellular transport of RNA drugs can considerably improve their effectiveness. These promising therapies are currently used to treat rare genetic diseases.

In modern medicine, personalized therapies are becoming increasingly important, especially in the treatment of genetic diseases. Such a promising approach is the use of so -called antissens (ASOS) oligonucleotides. These small synthetic molecules interfere specifically with cellular metabolism by preventing the production of pathogenic proteins. These RNA therapies are already successfully used to treat previously incurable genetic disorders such as amyotrophic lateral sclerosis (SLA) and Duchenne muscular dystrophy.

Limited efficacy of RNA medications

A key challenge, however, is that most ASOs fail to reach their targeted target within the cell and therefore cannot reach their complete therapeutic potential. In a collaborative study published in Nature communicationsAn international research team – including Professor Anne Spang from the Biozentrum of the University of Basel and the scientists of Roche – used CRISPR / CAS9 technology to identify the factors that considerably influence ASO activity. The results open up new ways to improve the efficiency of RNA therapy and accelerate their development.

Antisen nucleotides are tiny genetic fragments designed to measure which specifically bind to RNA molecules in the cell, thus interfering with the synthesis of proteins. Once administered, most ASOs are absorbed by the cell and reach the sorting stations of the cell, so-called endosomes, via small transport vesicles.

To exercise their therapeutic effect, they must escape endosomes. Otherwise, they are declared as “cellular waste” and have quickly returned to lysosomes for degradation. Since ASOS fraction manages to escape, their overall efficiency is limited.

Residence time in endosomes as a critical factor

The probability that asos escape endosomes are closely linked to the speed of intracellular transport: the longer they stay in the endosome, the more they should escape. Using a CRISPR / CAS9 screen on the genome scale, researchers systematically eliminated thousands of genes to study their impact on ASO efficiency.

“We have identified a large number of genes that improve or alter ASO activity,” said Dr. Liza Malong, principal author and researcher at Roche. “Many of these genes are involved in the intracellular transport of the ASOS.”

The team also discovered that the AP1M1 gene plays a key role in this process: it regulates the transport of the endosome to the lysosome. “By selectively off this gene, the ASOS remain longer in specific endosomes,” explains the main co-author, Dr Filip Roudnicky, also a researcher at Roche.

“This prolonged residence time increases their chances of escaping endosomes and becoming effective.” In cell cultures and a mouse model, this approach has considerably improved the effectiveness of ASO without requiring an increased dose.

Towards more effective RNA therapies

The study provides a complete overview of the genes that modulate ASO activity and demonstrates that the slowdown in endosomal transport can stimulate the therapeutic efficiency of the ASOS. “The key to more effective therapies therefore lies not only in the medication itself, but also in intracellular traffic,” adds Spang.

“This concept can also apply to other drugs and even bacterial and viral pathogens. The shortening of the stay of pathogens in endosomes could reduce their risks of escaping and replying in the cell. This could represent a new strategy in the fight against infections.”