Oncogenesis Unit

Restriction factors are host cell proteins that play a role in limiting virus replication. They form part of the intrinsic immune system and function as a first line of defense against viral infections. Hepatitis B virus (HBV) does not escape this rule and TREX1, a host restriction enzyme acts as an antiviral factor, leading to the inhibition of the virus. TREX1-expressing constructs were generated and modified by site-directed mutagenesis.

Method details Clonogenic assay 500 cells (D1 and D8 in serum+Lif medium; D18 in N2B27 + Lif) were seeded in 6-well plates. After 6 days, cells were fixed with 4% paraformaldehyde for 5 min and washed twice with PBS. Colonies were stained using Alkaline Phosphatase Blue Membrane Solution Kit (Sigma #AB0300) for 15 min in the dark. Wells were washed once with PBS and left to dry. Plates were scanned and colonies were counted using ImageJ.

Highlights • Endogenous SUMO2/3 proteomics in ESCs and MEFs uncovers drastic SUMOylome rewiring • In ESCs, SUMO2/3 targets densely interconnected repressive chromatin proteins • In MEFs, SUMO2/3 targets key determinants of fibroblastic cell identity • SUMOylation of Dppa2/4 prevents conversion of ESCs to the 2C-like state Summary Post-translational modification by SUMO is a key regulator of cell identity.