title: Quantitative comparison of constitutive promoters in human ES cells.
abstract: BACKGROUND
  Constitutive promoters that ensure sustained and high level gene expression are basic research tools that have a wide range of applications, including studies of human embryology and drug discovery in human embryonic stem cells (hESCs). Numerous cellular/viral promoters that ensure sustained gene expression in various cell types have been identified but systematic comparison of their activities in hESCs is still lacking.
  
  
  RESULTS
  We have quantitatively compared promoter activities of five commonly used constitutive promoters, including the human β-actin promoter (ACTB), cytomegalovirus (CMV), elongation factor-1α, (EF1α), phosphoglycerate kinase (PGK) and ubiquitinC (UbC) in hESCs. Lentiviral gene transfer was used to ensure stable integration of promoter-eGFP constructs into the hESCs genome. Promoter activities were quantitatively compared in long term culture of undifferentiated hESCs and in their differentiated progenies.
  
  
  CONCLUSIONS
  The ACTB, EF1α and PGK promoters showed stable activities during long term culture of undifferentiated hESCs. The ACTB promoter was superior by maintaining expression in 75-80% of the cells after 50 days in culture. During embryoid body (EB) differentiation, promoter activities of all five promoters decreased. Although the EF1α promoter was downregulated in approximately 50% of the cells, it was the most stable promoter during differentiation. Gene expression analysis of differentiated eGFP+ and eGFP- cells indicate that promoter activities might be restricted to specific cell lineages, suggesting the need to carefully select optimal promoters for constitutive gene expression in differentiated hESCs.
authors.affiliation: Department of Laboratory Medicine, Lund Center for Stem Cell Biology and Cell Therapy, Lund University, Lund, Sweden.
authors.forename: Karin
authors.initials: K
authors.lastname: Norrman
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Fischer
authors.forename: Blandine
authors.initials: B
authors.lastname: Bonnamy
authors.forename: Fredrik
authors.initials: F
authors.lastname: Wolfhagen Sand
authors.forename: Philippe
authors.initials: P
authors.lastname: Ravassard
authors.forename: Henrik
authors.initials: H
authors.lastname: Semb
mesh_terms: D000199:Actins / Q000235:genetics; D002454:Cell Differentiation; D002460:Cell Line; D053595:Embryonic Stem Cells / Q000166:cytology*; D005786:Gene Expression Regulation; D006801:Humans; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010735:Phosphoglycerate Kinase / Q000235:genetics; D011401:Promoter Regions, Genetic; D025822:Ubiquitin C / Q000235:genetics
chemical_list: D000199:Actins; D020648:Peptide Elongation Factor 1; D025822:Ubiquitin C; D010735:Phosphoglycerate Kinase