Sp3 Transcription Factor Is Crucial for Transcriptional Activation of the Human NOX4 Gene

FEBS J. 2011 Apr;278(6):964-72. doi: 10.1111/j.1742-4658.2011.08018.x. Epub 2011 Feb 5.

Abstract

NOX is the catalytic subunit of NADPH oxidase, the superoxide-generating enzyme. Among several isoforms of NOX, NOX4 is abundantly expressed in various tissues. To clarify the mechanisms of constitutive and ubiquitous expression of NOX4, the promoter activities of the human NOX4 gene were analyzed by reporter assays. The 5'-flanking and non-coding regions of the human NOX4 gene are known to contain multiple GC bases. Among them, three GC-boxes containing putative Sp/Klf-binding sites, which were not found in rodent genes, were suggested to be essential for the basal expression of the NOX4 gene in SH-SY5Y and HEK293 cells. Electrophoresis mobility shift assays demonstrated that Sp1 and Sp3 could bind to GC-boxes at positions -239/-227 and +69/+81 in these cells. Chromatin immunoprecipitation assays showed that Sp1 and Sp3 could also bind to GC-boxes at positions -239/-227 and +69/+81 in vivo. The promoter activity of the NOX4 gene was reduced in SH-SY5Y and HEK293 cells by transfection of an anti-Sp3 short hairpin RNA-expression plasmid. Taken together, these results suggest that Sp3 plays a key role in the expression of NOX4 in various cell lineages in humans.

MeSH terms

  • Base Sequence
  • Electrophoretic Mobility Shift Assay
  • HEK293 Cells
  • Humans
  • Molecular Sequence Data
  • NADPH Oxidase 4
  • NADPH Oxidases / genetics*
  • Promoter Regions, Genetic
  • Sequence Alignment
  • Sp1 Transcription Factor / metabolism
  • Sp3 Transcription Factor / physiology*
  • Transcriptional Activation*

Substances

  • SP3 protein, human
  • Sp1 Transcription Factor
  • Sp3 Transcription Factor
  • NADPH Oxidase 4
  • NADPH Oxidases
  • NOX4 protein, human