The SUMOylation of zinc-fingers and homeoboxes 1 (ZHX1) by Ubc9 regulates its stability and transcriptional repression activity.

ABSTRACT Zinc‐fingers and homeoboxes protein 1 (ZHX1) belongs to the ZF (zinc‐fingers) class of homeodomain transcription factors, and its functionremainslargelyunknown.ZHX1hasbeenpreviouslyfoundtointeractwiththeactivationdomainofthenuclearfactorYsubunitA(NFYA)andto havea transcriptional repression activity. Here, we report thatthe SUMO‐E2 conjugating enzymeUbc9 was identified tointeract with ZHX1by an interaction screen using a yeast two‐hybrid system. This interaction was confirmed by co‐immunoprecipitation and co‐localizationassays.FurtherstudyshowedthatZHX1isSUMOylatedbyUbc9withSUMO1atthesitesK159,K454,andK626.Furthermore,wedemonstratedthat the SUMOylation of ZHX1 regulated the stability, ubiquitination and transcriptional activity of ZHX1. J. Cell. Biochem. 114: 2323–2333,2013. 2013 Wiley Periodicals, Inc. KEY WORDS: ZHX1; SUMO; SUMOYLATION; TRANSCRIPTIONAL ACTIVITY Z inc‐fingersandhomeoboxes protein 1 (ZHX1), first discoveredinamousebonemarrowstromalcellline,isamemberoftheZFclassofhomeodomaintranscriptionfactors[Barthelemyetal.,1996].ZHX1 contains two Cys