Study of Xist-mediated gene silencing using iXist

Abstract

X Chromosome Inactivation (XCI) is an example of dosage compensation in mammals in which one of the X chromosomes in females is inactivated to balance the gene dosage between males and females. This process is dependent on a long non-coding RNA (lncRNA) called Xist. Previous report showed that Xist cDNA was sufficient to cause gene silencing in mouse cells. In this study, we used an inducible-expression system to compare the gene silencing capability of full length Xist and Xist cDNA directly. Both transgenes showed efficient gene silencing effect but full length Xist showed a slight but significant higher gene silencing capacity as compared to that of Xist cDNA. This shows that RNA splicing or the presence of introns may play a role in Xist-mediated gene silencing. Different Xist mutants such as Xist cDNA with insertion of intron 1 or 4 were then generated to determine the specific roles of RNA splicing and presence of introns.