Diagnostic area

RNAu

The expression of toxic genes leads to many human diseases. Most viral infections, many hereditary disorders and cancer are caused by gene expression of viral genes, dominant negative genes or oncogenes, respectively. Therefore, it is essential to develop technology aimed to inhibit gene expression of specific genes. The specific inhibition of the expression of toxic genes that does not affect the expression of cellular non-toxic genes should cure many diseases without secondary effects.

Specific gene expression inhibition has been recently obtained with RNA interference (RNAi). We have developed a similar technique named RNAu, based in 5´-end modified U1 snRNP. This technique involves introduction in the cells of genes similar to the ones that transcribe U1 snRNP, an abundant small nuclear RNA involved in gene expression. When the 5´-end modified U1 snRNP binds close to the 3´-end of an mRNA target, proper mRNA maturation is avoided and therefore mRNA expression is blocked by a well-characterized molecular mechanism. When the 5´-end modified U1 snRNP targets the mRNA that encodes a toxic protein, toxic protein expression is inhibited.

In our hands, gene expression inhibitions obtained with RNAu are stronger than inhibitions obtained by RNAi. Also, inhibition increases synergistically when several 5´-end modified U1 snRNPs are used that target the same mRNA. Using RNAu, we have successfully inhibited gene expression of cellular genes in tissue culture, both transiently and stably. This shows that RNAu is not toxic for the cell. We are currently using RNAu to inhibit endogenous gene expression in mouse models and we are evaluating the specificity of RNAu.

Luciferase gene expression in inhibited and control mice. Luciferase gene contains sequences that bind endogenous U1 snRNA and therefore inhibition is observed. Point mutations in these sequences allow gene expression. Luciferase activity was been evaluated with a luminometer (IVIS System. Xenogen).