title: Epigenetic repression of SATB1 by polycomb group protein EZH2 in epithelial cells.
abstract: OBJECTIVE
  To study the regulatory mechanism of SATB1 repression in cells other than T cells or erythroid cells, which have high expression level of SATB1.
  
  
  METHODS
  HeLa epithelial cells were treated with either histone deacetylase inhibitor (HDACi) trichostatin A (TSA) or DNA methylation inhibitor 5-Aza-C before detecting SATB1 expression. Luciferase reporter system was applied to measure effects of EZH2 on SATB1 promoter activity. Over-expression or knockdown of EZH2 and subsequent quantitative reverse transcription-polymerase chain reaction were performed to determine the effect of this Polycomb group protein on SATB1 transcription. Chromatin immunoprecipitation (ChIP) assay was applied to measure enrichment of EZH2 and trimethylated H3K27 (H3K27me3) at SATB1 promoter in HeLa cells. K562 cells and Jurkat cells, both having high-level expression of SATB1, were used in the ChIP experiment as controls.
  
  
  RESULTS
  Both TSA and 5-Aza-C increased SATB1 expression in HeLa cells. Over-expression of EZH2 reduced promoter activity as well as the mRNA level of SATB1, while knockdown of EZH2 apparently enhanced SATB1 expression in HeLa cells but not in K562 cells and Jurkat cells. ChIP assay Results suggested that epigenetic silencing of SATB1 by EZH2 in HeLa cells was mediated by trimethylation modification of H3K27. In contrast, enrichment of EZH2 and H3K27me3 was not detected within proximal promoter region of SATB1 in either K562 or Jurkat cells.
  
  
  CONCLUSIONS
  SATB1 is a bona fide EZH2 target gene in HeLa cells and the repression of SATB1 by EZH2 may be mediated by trimethylation modification on H3K27.
authors.affiliation: Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, China.
authors.forename: Li
authors.initials: L
authors.lastname: Lei
authors.forename: Lu
authors.initials: L
authors.lastname: Lu
authors.forename: Lv
authors.initials: L
authors.lastname: Xiang
authors.forename: Wu
authors.initials: W
authors.lastname: Xue-song
authors.forename: Liu
authors.initials: L
authors.lastname: De-pei
authors.forename: Liang
authors.initials: L
authors.lastname: Chih-chuan
mesh_terms: D001374:Azacitidine / Q000494:pharmacology; D001483:Base Sequence; D002460:Cell Line; D047369:Chromatin Immunoprecipitation; D019175:DNA Methylation; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000502:physiology*; D000071221:Enhancer of Zeste Homolog 2 Protein; D044127:Epigenesis, Genetic / Q000502:physiology*; D004848:Epithelium / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology; D036961:Matrix Attachment Region Binding Proteins / Q000235:genetics*; D063151:Polycomb Repressive Complex 2; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000502:physiology*
chemical_list: D017931:DNA Primers; D004268:DNA-Binding Proteins; D006877:Hydroxamic Acids; D036961:Matrix Attachment Region Binding Proteins; C076189:SATB1 protein, human; D014157:Transcription Factors; C012589:trichostatin A; C498409:EZH2 protein, human; D000071221:Enhancer of Zeste Homolog 2 Protein; D063151:Polycomb Repressive Complex 2; D001374:Azacitidine