Arsenic trioxide stimulates SUMO-2/3 modification leading to RNF4-dependent proteolytic targeting of PML

Abstract 

We have recently reported that poly-SUMO-2/3 conjugates are subject to a ubiquitin-dependent proteolytic control in human cells. Here we show that arsenic trioxide (ATO) increases SUMO-2/3 modification of promyelocytic leukemia (PML) leading to its subsequent ubiquitylation in vivo. The SUMO-binding ubiquitin ligase RNF4 mediates this modification and causes disruption of PML nuclear bodies upon treatment with ATO. Reconstitution of SUMO-dependent ubiquitylation of PML by RNF4 in vitro and in a yeast trans vivo system revealed a preference of RNF4 for chain forming SUMOs. Polysumoylation of PML in response to ATO thus leads to its recognition and ubiquitylation by RNF4.

Abbreviations: ATO, arsenic trioxide, Ni-NTA, nickel-nitrilo triacetic acid, GSH, glutathione, GST, glutathione S-transferase, His₆, 6×His tag, NB, nuclear body, PML, promyelocytic leukemia, RING, relatively interesting new gene, RNF4, RING finger protein 4, SAE, SUMO activating enzyme, SIM, SUMO interaction motif, SUMO, small ubiquitin-related modifier, UBC9, SUMO conjugating enzyme, ULS, ubiquitin ligase for SUMO conjugates

Keywords: Small ubiquitin-like modifier, Ubiquitin, Relatively interesting new gene finger, Protein degradation, Promyelocytic leukemia