The Wilms' tumor suppressor Wt1 encodes a transcriptional activator of the class IV POU-domain factor Pou4f2 (Brn-3b)

Gene. 2003 Feb 27;305(2):217-23. doi: 10.1016/s0378-1119(02)01231-3.

Abstract

The Wilms' tumor gene Wt1 encodes a zinc finger protein, which is required for normal formation of the genitourinary system and mesothelial tissues. Our recent findings indicate that Wt1 also plays a critical role in the development of ganglion cells in the vertebrate retina. Here we show that the POU-domain factor Pou4f2 (formerly Brn-3b), which is necessary for retinal ganglion cell survival, is up-regulated in human embryonic kidney (HEK)293 cells with stable Wt1 expression. Consistent with our previous observations of increased Pou4f2 mRNA in stably Wt1-transfeced HEK293 cells [EMBO J. 21 (2002) 1398], endogenous Pou4f2 was also elevated at the protein level in the HEK293 transfectants as well as in U2OS osteosarcoma cells that expressed an inducible Wt1 isoform. Transient co-transfection of a Wt1 expression construct activated a Pou4f2 promoter-reporter construct approximately 4-fold. Stimulation of the Pou4f2 promoter required a Wt1 binding element that was similar to a degenerative consensus site previously identified in other Wt1 responsive genes. Double-immunofluorescent labeling revealed co-expression of Pou4f2 and Wt1 in glomerular podocytes of adult kidney and in developing retinal ganglion cells of mouse embryos. Pou4f2 immunoreactivity was absent from the retinas of Wt1(-/-) embryos. In conclusion, we identified Pou4f2 as a novel downstream target gene of Wt1. Co-localization of both proteins in glomerular podocytes of the kidney and in developing retinal ganglion cells suggests a role for Wt1-Pou4f2 interaction in these tissues.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Electrophoretic Mobility Shift Assay
  • Female
  • Humans
  • Immunoblotting
  • Immunohistochemistry
  • Kidney / metabolism
  • Luciferases / genetics
  • Luciferases / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Protein Binding
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Regulatory Sequences, Nucleic Acid / genetics
  • Retina / embryology
  • Retina / metabolism
  • Transcription Factor Brn-3
  • Transcription Factor Brn-3B
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcriptional Activation
  • Transfection
  • Tumor Cells, Cultured
  • WT1 Proteins / genetics
  • WT1 Proteins / metabolism*

Substances

  • DNA-Binding Proteins
  • POU4F2 protein, human
  • Recombinant Fusion Proteins
  • Transcription Factor Brn-3
  • Transcription Factor Brn-3B
  • Transcription Factors
  • WT1 Proteins
  • Luciferases