Exploration of nuclear body-enhanced sumoylation reveals that PML represses 2-cell features of embryonic stem cells

Membrane-less organelles are condensates formed by phase separation whose functions often remain enigmatic. Upon oxidative stress, PML scaffolds Nuclear Bodies (NBs) to regulate senescence or metabolic adaptation. PML NBs recruit many partner proteins, but the actual biochemical mechanism underlying their pleiotropic functions remains elusive. Similarly, PML role in embryonic stem cell (ESC) and retro-element biology is unsettled. Here we demonstrate that PML is essential for oxidative stress-driven partner SUMO2/3 conjugation in mouse ESCs (mESCs) or leukemia, a process often followed by their poly-ubiquitination and degradation. Functionally, PML is required for stress responses in mESCs. Differential proteomics unravel the KAP1 complex as a PML NB-dependent SUMO2-target in arsenic-treated APL mice or mESCs. PML-driven KAP1 sumoylation enables activation of this key epigenetic repressor implicated in retro-element silencing. Accordingly, Pml mESCs re-express transposable elements and display 2-Cell-Like features, the latter enforced by PML-controlled SUMO2-conjugation of DPPA2. Thus, PML orchestrates mESC state by coordinating SUMO2-conjugation of different transcriptional regulators, raising new hypotheses about PML roles in cancer.
This work was supported by grants from Agence Nationale pour la Recherche, ANR SUMOPiv (V.L.B.); the ERC, PML-Therapy (ADG-785917) (H.D.T.); Fondation ARC (V.L.B.); ANRJC (P.T.). We kindly thank the staff of the animal facility in Research Institute of Saint–Louis (IRSL), A.L. Maubert for her help with mouse care. We are also grateful to image core microscopy facilities of IRSL and College de France, Paris, in particular N. Setterblad for his helpful advice with incucyte analysis. We warmly thank M. Tirard and N. Brose (Max Planck Institute of Experimental Medicine, Göttingen, Germany) for the sharing of His6-HA-Sumo1 knock-in mice, and Meng-Er Huang (Institut Curie, Orsay, France) for his GRX1-roGFP2 construct. We thank Pablo Navarro (Pasteur) for providing mESCs. We also acknowledge P. Mayeux and V. Salnot of the Proteomic 3P5 platform in Cochin hospital, Paris, France, for the total APL proteomics. The Orbitrap Fusion mass spectrometer was acquired with funds from the FEDER through the « Operational Programme for Competitiveness Factors and employment 2007-2013 », and from the « Cancéropôle Ile-de-France ». We kindly thank P. Lesage, A. Amara, M.H. Verhlac and D. Bourch’is for their critical readings of the manuscript, and other members of the team for helpful advice. We finally thank the support services of IRSL and CIRB.