Role of the Small Subunit Processome in the Maintenance of Pluripotent Stem Cells

RNA-binding proteins (RBPs) play integral roles in gene regulation, yet only a small fraction of RBPs has been studied in the context of stem cells. We here apply RNA interference screen for RBPs in mouse embryonic stem cells (ESCs) and identify 16 RBPs involved in pluripotency maintenance. Interestingly, six identified RBPs including Krr1 and Ddx47 are part of a complex called Small Subunit Processome (SSUP) that mediates 18S rRNA biogenesis. The SSUP components are preferentially expressed in stem cells and enhance global translational rate, which is critical to sustain the protein levels of labile pluripotency factors such as Nanog and Esrrb. Furthermore, the SSUP proteins are required for efficient reprogramming of induced pluripotent stem cells. Our study uncovers the role of SSUP and the importance of translational control in stem cell fate decision.