Abstract: The Promyelocytic Leukemia protein (PML) and its associated nuclear bodies have re-cently emerged as essential factors for maintaining the characteristics of embryonic stem (ES) cells. However, the full repertoire of PML driven gene regulatory events in ES cells is not resolved. In this report we have studied the role of PML in shaping the proteomic and SUMO proteomic landscape in ES cells. Our analysis of the PML KD proteome revealed a suppression of proteins related with self-renewal and an up-regulation of proteins vital for translation and proteasome functions, reflecting a cellular transition from pluripotency to differentiation. Major targets of PML-directed sumoylation include pluripotency factors, chromatin organizers and cell cycle regulators. We demonstrate that PML promotes the sumoylation of SALL1 and CDCA8, two proteins that are highly expressed in undifferentiated ES cells. SALL1 sumoylation increases the activation of the Wnt pathway, contributing to its ability to inhibit ES cell differentiation. Similarly, CDCA8 sumoylation enhances its capacity to promote cell proliferation. Our results demonstrate that PML maintains ES cell functions by modulating the abundance or sumoylation of key regulators involved in pluripotency and cell cycle progression.