Modulation of PLAGL2 transactivation activity by Ubc9 co-activation not SUMOylation

Biochem Biophys Res Commun. 2008 Sep 26;374(3):570-5. doi: 10.1016/j.bbrc.2008.07.064. Epub 2008 Jul 23.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Lung / metabolism
  • Promoter Regions, Genetic
  • Pulmonary Surfactant-Associated Protein C / genetics*
  • RNA-Binding Proteins / metabolism*
  • SUMO-1 Protein / metabolism
  • Transcription Factors / metabolism*
  • Transcriptional Activation*
  • Ubiquitin-Conjugating Enzymes / metabolism*

Substances

  • DNA-Binding Proteins
  • PLAGL2 protein, human
  • Pulmonary Surfactant-Associated Protein C
  • RNA-Binding Proteins
  • SUMO-1 Protein
  • SUMO1 protein, human
  • Transcription Factors
  • Ubiquitin-Conjugating Enzymes
  • ubiquitin-conjugating enzyme UBC9