DEAD box RNA helicases catalyze the ATP-dependent unwinding of doublestranded RNA. In addition, they are required for protein displacement and remodelling of RNA or RNA/protein complexes. P68 RNA helicase regulates the alternative splicing of the important protooncogene H-Ras, and numerous studies have shown that p68 RNA helicase is probably involved in miRNA biogenesis, mainly through Drosha and RISC/DICER complexes. In this study, a team of researchers led by Mariette Kokolo, Montse Bach-Elias, Instituto de Investigaciones Biomédicas de Barcelona-Consejo Superior de Investigaciones Científicas, Barcelona, determine how p68 RNA helicase affects the activity of selected mature miRNAs. The researchers included miR-342, miR-330, miR-138 and miR-206, miR-126 and miR-335, and let-7a in their experiment, which are known to be related to cancer processes.
The miRNA levels were analysed in stable HeLa cells containing p68 RNA helicase RNAi induced by doxycycline (DOX). Relevant results were repeated using transient transfection with pSuper/ pSuper-p68 RNA helicase RNAi to avoid DOX interference. Kokolo and Elias’ research demonstrates that p68 RNA helicase downregulation increases accumulation of the mature miRNAs miR-126, let-7a, miR-206 and miR-138. Interestingly, the accumulation of these mature miRNAs does not downregulate their known protein targets, thus suggesting that p68 RNA helicase is required for mature miRNA active RNA-induced silencing complex (RISC) complex activity. Furthermore, the study demonstrate that this requirement is conserved, as drosophila p68 RNA helicase can complete the p68 RNA helicase depleted activity in human cells. Dicer and Drosha proteins are not affected by downregulation of p68 RNA helicase despite the fact that Dicer is also localized in the nucleus when p68 RNA helicase activity is reduced. While a role of the P68 gene is believed to be linked to cancer, more research may be needed to be conducted to see if the P68 gene can be considered a viable pharmaceutical target. Learn moe about the study in the journal, MiRNA.
Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.