Oncogenic Ras upregulates NADPH oxidase 1 gene expression through MEK-ERK-dependent phosphorylation of GATA-6

Oncogene. 2008 Aug 21;27(36):4921-32. doi: 10.1038/onc.2008.133. Epub 2008 May 5.


Ras oncogene upregulates the expression of nicotinamide adenine dinucleotide phosphate oxidase (Nox) 1 via the Raf/MEK/ERK pathway, leading to the elevated production of reactive oxygen species that is essential for maintenance of Ras-transformation phenotypes. However, the precise transcriptional control mechanism underlying Ras-induced Nox1 expression remains to be elucidated. Here we demonstrated that via the MEK/ERK pathway, Ras signaling enhances the activity of the functional Nox1 promoter (nt -321 to -1) in colon cancer CaCo-2 cells and thereby induces the formation of the specific protein-DNA complexes in the two GATA-binding site-containing regions (nt -161 to -136 and -125 to -100). Supershift assays with GATA antibodies, protein analyses and chromatin immunoprecipitation revealed that GATA-6 is a component of the specific protein-DNA complexes at the Nox1 promoter. GATA-6 was able to trans-activate the Nox1 promoter but not a promoter in which the GATA-binding sites are mutated. Moreover, GATA-6 was phosphorylated at serine residues by MEK-activated ERK, which increased GATA-6 DNA binding, correlating with suppression of the Nox1 promoter activity by an MEK inhibitor PD98059. Finally, the site-directed mutation of the consensus ERK phosphorylation site (PYS(120)P to PYA(120)P) of GATA-6 abolished its trans-activation activity, suppressing of the growth of CaCo-2 cells. On the basis of these results, we propose that oncogenic Ras signaling upregulates the transcription of Nox1 through MEK-ERK-dependent phosphorylation of GATA-6.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Caco-2 Cells
  • DNA Primers
  • Electrophoretic Mobility Shift Assay
  • GATA6 Transcription Factor / metabolism*
  • Genes, Reporter
  • Humans
  • Mitogen-Activated Protein Kinases / metabolism*
  • NADH, NADPH Oxidoreductases / genetics*
  • NADPH Oxidase 1
  • Oncogene Protein p21(ras) / physiology*
  • Phosphorylation
  • Promoter Regions, Genetic
  • RNA, Messenger / genetics
  • Signal Transduction
  • Up-Regulation / physiology*


  • DNA Primers
  • GATA6 Transcription Factor
  • RNA, Messenger
  • NADH, NADPH Oxidoreductases
  • NADPH Oxidase 1
  • Mitogen-Activated Protein Kinases
  • Oncogene Protein p21(ras)