Seminar "microRNAs trigger dissociation of eIF4AI and II from target mRNAs in humans."

Dear all,

Cell Signal Unit would like to invite you to a seminar by Prof. Toshinobu Fujiwara.

We look forward to your participation.

Speaker:

Prof. Toshinobu Fujiwara

Faculty of Pharmacy,Kinki University

Title:

microRNAs trigger dissociation of eIF4AI and II from target mRNAs in humans

Abstract:

In animals, key functions of microRNA (miRNA)-induced silencing complex (miRISC) are translational repression and deadenylation followed by mRNA decay. It has been demonstrated that miRISC represses translation initiation. However, it is poorly understood how miRISC exerts this function. Here we assessed the effect of miRISC on synergistic recruitment of translation initiation factors to target mRNAs by using direct biochemical assays. We show that miRISC promotes the release of both eIF4AI and eIF4AII but not eIF4E and eIF4G from target mRNAs and demonstrate that this is independent of deadenylation. Strikingly, both, the miRISC-induced release of eIF4A I and II from the cap binding complex (CBC) and the miRISC-induced inhibition of cap- dependent translation can be counteracted by the RNA binding protein HuD via a direct interaction of HuD with eIF4A. In summary, we propose that eIF4AI and II are key targets in the translation initiation control mechanisms by miRISC.