title: Modulation of PLAGL2 transactivation activity by Ubc9 co-activation not SUMOylation.
abstract: Pleomorphic adenoma gene like-2 (PLAGL2), a developmentally regulated and stress inducible zinc finger protein can be post-translationally modified by small ubiquitin-like modifier peptide (SUMO-1); and SUMOylation attenuates PLAGL2 activity on the interactive promoter. Since PLAGL2 was a transactivator of the surfactant protein-C (SP-C) promoter, we hypothesized that SUMOylation down-regulated PLAGL2-activated SP-C promoter activity. Unexpectedly, the SUMO-conjugating enzyme Ubc9 enhanced, rather than reduced, PLAGL2 activated promoter activity but did not affect TTF-1 activation of the promoter. Ubc9 mutant (Ubc9-C93S) defective in SUMO-conjugating activity also enhanced PLAGL2-driven promoter activity suggesting that the stimulatory effect of Ubc9 on SP-C promoter activation was independent of its enzymatic function. PLAGL2 mutants without the K250 and/or K269 SUMOylation sites did not further improve PLAGL2 programmed transcription nor did they abolish Ubc9 enhanced promoter activity supporting the SUMOylation-independent mechanism. Chromatin immunoprecipitation (ChIP) assay demonstrated the association of PLAGL2 and Ubc9 with the SP-C promoter in vivo. Taken together, our data suggests that Ubc9 can function as a co-factor of PLAGL2, uncoupling from its enzymatic activity, to mediate PLAGL2 interactive SP-C promoter activity.
authors.affiliation: Department of Internal Medicine, Pulmonary and Critical Care Medicine, UT Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390-8558, USA.
authors.forename: Yuhong
authors.initials: Y
authors.lastname: Guo
authors.forename: Meng-Chun W
authors.initials: MC
authors.lastname: Yang
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Weissler
authors.forename: Yih-Sheng
authors.initials: YS
authors.lastname: Yang
mesh_terms: D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D008168:Lung / Q000378:metabolism; D011401:Promoter Regions, Genetic; D037721:Pulmonary Surfactant-Associated Protein C / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D025842:SUMO-1 Protein / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D044763:Ubiquitin-Conjugating Enzymes / Q000378:metabolism*; D000098843:Ubiquitin-Conjugating Enzyme UBC9
chemical_list: D004268:DNA-Binding Proteins; C114598:PLAGL2 protein, human; D037721:Pulmonary Surfactant-Associated Protein C; D016601:RNA-Binding Proteins; D025842:SUMO-1 Protein; C495501:SUMO1 protein, human; D014157:Transcription Factors; D044763:Ubiquitin-Conjugating Enzymes; D000098843:Ubiquitin-Conjugating Enzyme UBC9