DGCR8 is essential for the miRNA biogenesis (Han et al., 2004, 2006; Quick-Cleveland et al., 2014). We recently reported that at K707-SUMOylation of DGCR8 influences its affinity with pri-miRNAs and controls the direct functions of pri-miRNAs in gene silencing. However, the K707R mutation does not remove all SUMO1 modifications of DGCR8 (Zhu et al., 2015), suggesting that DGCR8 bears other SUMOylation sites. Here, we identified K259 as an alternative site for DGCR8 SUMOylation that was directly promoted by p14ARF in the nucleus. We also demonstrated a notable role of K259-SUMOylation in preventing DGCR8 nuclear export that is required for its function in the processing of pri-miRNAs into pre-miRNAs and tumor suppression.
