Alternative splicing and embryonic expression of the Xenopus mad4 bHLH gene

Craig S. Newman, Paul A Krieg

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

The cell proliferative activity of the Myc family of basic helix-loop- helix/leucine zipper (bHLHZip) transcription factors is dependent upon binding to the ubiquitous Max protein. In the absence of heterodimerization with Max, Myc protein is unable to efficiently bind to DNA and activate transcription. Members of the Mad family of transcription factors are thought to modulate the cell proliferative effects of the c-myc proto-oncogene by binding to Max, directly competing with the Myc protein for both heterodimerization and DNA binding. Consistent with a role in down- regulating cell division, the murine mad genes are expressed in embryonic tissues undergoing differentiation, often during or shortly after the down- regulation of myc gene expression. Here, we report the isolation and characterization of the first Xenopus mad family member, Xmad4. Maternal Xmad4 transcripts are present at high levels in the oocyte and in the cleavage stage embryo, but almost disappear by the neurula stage. Zygotic expression of the Xmad4 gene is initiated in the epidermis of the late neurula stage, and shortly thereafter, Xmad4 is transiently detectable in the cement and hatching glands. At later stages, expression is also observed in the developing pronephros and liver. Unlike the murine mad4 gene, we find that multiple Xmad4 splice variants exist in Xenopus and that these variants are differentially expressed in both the embryo and the adult. Despite the demonstrated antagonistic role of Mad proteins in the regulation of Myc activity, we show that the over-expression of Xmad4 in the cleavage-stage embryo has no detectable phenotypic effect, suggesting that Myc function is dispensable during early embryonic development.

Original languageEnglish (US)
Pages (from-to)170-178
Number of pages9
JournalDevelopmental Dynamics
Volume215
Issue number2
DOIs
StatePublished - 1999
Externally publishedYes

Fingerprint

Alternative Splicing
Xenopus
myc Genes
Embryonic Structures
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
Pronephros
Genes
DNA
Gene Expression Regulation
Epidermis
Cell Division
Oocytes
Embryonic Development
Proteins
Transcription Factors
Down-Regulation
Mothers
Gene Expression
Liver
Myc associated factor X

Keywords

  • Basic helix-loop-helix
  • Mad
  • Max
  • Myc
  • Xenopus

ASJC Scopus subject areas

  • Developmental Biology
  • Cell Biology

Cite this

Alternative splicing and embryonic expression of the Xenopus mad4 bHLH gene. / Newman, Craig S.; Krieg, Paul A.

In: Developmental Dynamics, Vol. 215, No. 2, 1999, p. 170-178.

Research output: Contribution to journalArticle

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