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A consensus Oct1 binding site is required for the activity of the Xenopus Cdx4 promoter

John S Reece-Hoyes1, Iain D Keenan, Mary Elizabeth Pownall

  • 1Area 11, Department of Biology, University of York, York YO10 5YW, UK.

Developmental Biology
|June 14, 2005
PubMed

Insights

Investigating the Xenopus laevis Cdx4 gene, this study identifies a conserved octamer-binding site crucial for regulating Cdx gene expression in vertebrate development and disease.

Area of Science:

  • Developmental Biology
  • Gene Regulation
  • Molecular Genetics

Background:

  • Cdx homeodomain transcription factors are vital for early vertebrate development.
  • Dysregulated Cdx gene expression is linked to gut metaplasias and cancers.
  • Understanding Cdx gene regulation is critical due to their roles in development and disease.

Purpose of the Study:

  • To analyze the upstream regulatory regions of the Xenopus laevis Cdx4 gene.
  • To identify key elements responsible for driving Cdx4 expression.
  • To investigate the role of octamer-binding proteins in Cdx gene regulation.

Main Methods:

  • Reporter gene assays using GFP expression in transgenic Xenopus embryos.
  • Deletion analysis of the Cdx4 upstream regulatory sequences.
  • Site-directed mutagenesis to assess the function of the octamer-binding site.
  • Comparative sequence analysis of Cdx gene promoters across species.

Main Results:

  • A 2.8 kb upstream region of Xenopus Cdx4 drives posterior expression in transgenic embryos.
  • A minimal 247-bp proximal promoter fragment retains posterior-driving activity.
  • A 63-bp fragment containing an octamer-binding site shows significant promoter activity.
  • Octamer-binding protein Oct1 induces Cdx4 reporter expression, and mutation of the octamer site abolishes this activity.
  • The identified octamer-binding site is conserved across human, mouse, chicken, zebrafish, and amphibian Cdx1/Cdx2 promoters.

Conclusions:

  • A conserved octamer-binding site in the Cdx4 promoter is essential for its activity.
  • Octamer-binding proteins play a conserved role in regulating Cdx family gene expression.
  • These findings provide insights into the molecular mechanisms governing Cdx gene regulation in development and disease.

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