Korean J Anat.  2000 Oct;33(5):595-608.

Transcriptional Regulation of the Xbr-1a/Xvent-2 Gene by BMP-4 Signaling during Xenopus Embryonic Development

Affiliations
  • 1Department of Biochemistry, College of Medicine, Hallym University, Chun-Cheon, 200-702, Korea.
  • 2Department of Anatomy, School of Medicine, KyungPook National University, Taegu, 700-422, Korea.
  • 3National Institute of Diabetes and Digestive and Kidney Diseases, Laboratory of Biochemistry and Genetics, Bethesda, Maryland 20892, USA.
  • 4Intramural Research Support Program, Science Applications International Corporation-Frederick, Frederick, Maryland 21702-1201, USA.
  • 5Institute of Molecular Biology, University of Hong Kong, Hong Kong.

Abstract

BMP-4 signaling is mediated through Smad proteins which may translocate to the nucleus to activate transcription. Little is known about how BMP-4 signaling regulates the transcription of its target genes, e.g., Xvent genes. Therefore, we isolated the genomic clone of a BMP-4 responsive homeobox gene, Xbr-1a/Xvent-2. This clone contains a promoter and three exons for the entire coding region. Using the primer extension, we identified the transcription initiation site corresponding to position -64 bp upstream to the ATG codon of the Xvent-2 gene. The promoter was linked to the luciferase reporter gene, and promoter activity determined by luciferase assay. The temporal promoter activity peaked between embryonic stages 13~17, in agreement with its temporal mRNA expression in the whole embryo. Through the serial deletion mutation, the upstream -235 bp of the promoter retains the full transcriptional activity, and is regulated by BMP-4 signaling. The present results suggest that the BMP-4 responsive element is located on the upstream 235 bp of the promoter.

Keyword

Xenopus laevis; Xbr-1a/Xvent-2; gene; Transcriptional regulation; Embryogenesis

MeSH Terms

Clinical Coding
Clone Cells
Codon
Embryonic Development*
Embryonic Structures
Exons
Female
Genes, Homeobox
Genes, Reporter
Luciferases
Pregnancy
RNA, Messenger
Sequence Deletion
Smad Proteins
Transcription Initiation Site
Xenopus laevis
Xenopus*
Codon
Luciferases
RNA, Messenger
Smad Proteins
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