Scientists shed light on how microRNAs repress protein synthesis

Witold Filipowicz and his team have discovered how microRNAs repress translation of mRNAs. In a structure-function study published in Molecular Cell, they report different modes of recruitment of the CCR4-NOT complex to mRNAs targeted by microRNAs. They also demonstrate that CCR4-NOT recruits and activates the ATPase DDX6, an important translational inhibitor. Activation of DDX6 by CCR4-NOT plays a key role in miRNA repression. As well as encoding information for protein synthesis, genomes of eukaryotic cells are transcribed into thousands of so-called non-coding RNAs, which perform a variety of essential structural and regulatory functions. Among the non-coding RNAs, one family is receiving particular attention - the ~20-nucleotide-long RNAs known as microRNAs (miRNAs). This family, comprising over 1,000 species, regulates the expression of more than half of all human genes.