1 The Faculty of Medicine, Aalborg University, VBN2 Aalborg University Hospital, The Faculty of Medicine, Aalborg University, VBN3 Klinik Medicin, The Faculty of Medicine, Aalborg University, VBN4 Blodsygdomme (Hæmatologi), The Faculty of Medicine, Aalborg University, VBN5 Biotech Research and Innovation Centre, Copenhagen Biocenter6 Biotech Research and Innovation Centre, Copenhagen Biocenter, University of Copenhagen7 Biotech Research and Innovation Centre and Centre for Epigenetics, University of Copenhagen8 Bioneer A/S, Hørsholm9 Santaris Pharma, Hørsholm10 Department of Clinical Medicine, The Faculty of Medicine, Aalborg University, VBN
microRNAs regulate the expression of over 60% of protein coding genes by targeting their mRNAs to AGO2-containing complexes in the cytoplasm and promoting their translational inhibition and/or degradation. There is little evidence so far for microRNA-mediated regulation of other classes of non-coding RNAs. Here we report that microRNA-9 (miR-9) regulates the expression of the Metastasis Associated Lung Adenocarcinoma Transcript 1 (MALAT-1), one of the most abundant and conserved long non-coding RNAs. Intriguingly, we find that miR-9 targets AGO2-mediated regulation of MALAT1 in the nucleus. Our findings reveal a novel direct regulatory link between two important classes of non-coding RNAs, miRs and lncRNAs, and advance our understanding of microRNA functions.