title: Mel-18 interacts with RanGAP1 and inhibits its sumoylation.
abstract: Our previous results showed that the polycomb protein mel-18 binds to a protein called HSF2 and inhibits HSF2 sumoylation, thereby functioning as an anti-SUMO E3 factor. This study also suggested that mel-18 regulates the sumoylation of other cellular proteins, but the identities of these other proteins were unknown. Here we show that mel-18 interacts with the RanGAP1 protein and inhibits its sumoylation, and that these activities do not require the RING domain of mel-18. The results also show that RanGAP1 sumoylation is decreased during mitosis, and that this is associated with increased interaction between RanGAP1 and mel-18 during this stage of the cell cycle. Intriguingly, this regulatory relationship is the opposite of that found for mel-18 and HSF2, in which the interaction between these two proteins decreases during mitosis, resulting in elevated HSF2 sumoylation. The results of this study strengthen the conclusion that mel-18 functions as an anti-SUMO E3 factor, and extend its targets to include regulation of the sumoylation of the important cellular protein RanGAP1.
authors.affiliation: Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Sarge
mesh_terms: D002460:Cell Line; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D006801:Humans; D063150:Polycomb Repressive Complex 1; D054829:RING Finger Domains / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D025841:Small Ubiquitin-Related Modifier Proteins / Q000037:antagonists & inhibitors*; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D004268:DNA-Binding Proteins; D020690:GTPase-Activating Proteins; C489348:PCGF2 protein, human; C092317:RANGAP1 protein, human; D012097:Repressor Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D044763:Ubiquitin-Conjugating Enzymes; D063150:Polycomb Repressive Complex 1; D000098843:Ubiquitin-Conjugating Enzyme UBC9