A Role for the RNA-Binding Protein MOS2 in MicroRNA Maturation in Arabidopsis. Arabidopsis thaliana

microRNAs (miRNAs) play important roles in the regulation of gene expression. In Arabidopsis, mature miRNAs are processed from primary miRNA transcripts (pri-miRNAs) by nuclear HYL1/SE/DCL1 complexes that form Dicing bodies (D-bodies). Here we report that a RNA-binding protein MOS2 bound to pri-miRNAs and was required for their efficient processing. MOS2 did not interact with HYL1, SE, and DCL1 and was not localized in D-bodies. Interestingly, in the absence of MOS2, the recruitment of pri-miRNAs by HYL1 was greatly reduced and the localization of HYL1 in D-bodies was compromised. These data suggest that MOS2 facilitates pri-miRNA processing through facilitating the recruitment of pri-miRNAs by the Dicing complexes. Overall design: Examination of gene expression profiles in Col-0 and mos2-2 plants by deep sequencing