title: Post-translational modification of POU domain transcription factor Oct-4 by SUMO-1.
abstract: POU domain transcription factor Oct-4 plays a crucial role in maintaining self-renewal and pluripotency of embryonic stem (ES) cells in a concentration-dependent manner. However, the molecular mechanism controlling Oct-4 levels in ES cells remains largely unknown. To explore the molecular mechanism regulating Oct-4 function, we constructed a mouse ES cell cDNA library and performed yeast two-hybrid screening using the POU domain of Oct-4 as bait. Here, we present novel evidence for Oct-4 interaction with Ubc9, an E2 conjugation enzyme for SUMO modification, and its modification by SUMO-1. The SUMO acceptor site was identified at lysine residue 118. Importantly, disruption of Oct-4 sumoylation reduced Oct-4 protein stability and self-renewal capacity in ES cells. Interestingly, expression of cYes was found to reduce when Oct-4 sumoylation was disrupted or Oct-4 expression downregulated in ES cells. We further demonstrate that Oct-4 was recruited to the cYes promoter region, suggesting that cYes might be a novel downstream gene of Oct-4. Taken together, we first demonstrate the post-translational modification of endogenous Oct-4 by SUMO and the role of sumoylation in regulating Oct-4 protein stability and function. Our findings provide new evidence for the important role of post-translational modification in controlling Oct-4 function in ES cells.
authors.affiliation: Institute of Health Sciences, Shanghai Jiao Tong University School of Medicine, Chinese Academy of Sciences, Shanghai, China 200025.
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Zhang
authors.forename: Bing
authors.initials: B
authors.lastname: Liao
authors.forename: Ming
authors.initials: M
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000818:Animals; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology / Q000502:physiology*; D005786:Gene Expression Regulation; D006801:Humans; D008239:Lysine / Q000378:metabolism; D051379:Mice; D050814:Octamer Transcription Factor-3 / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D051575:Proto-Oncogene Proteins c-yes / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D044763:Ubiquitin-Conjugating Enzymes / Q000235:genetics / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D050814:Octamer Transcription Factor-3; D011993:Recombinant Fusion Proteins; D025842:SUMO-1 Protein; D014452:Ubiquitins; D044763:Ubiquitin-Conjugating Enzymes; D051575:Proto-Oncogene Proteins c-yes; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000098843:Ubiquitin-Conjugating Enzyme UBC9; D008239:Lysine