Structure, chromosomal localisation and expression of the murine dominant negative helix-loop-helix Id4 gene

Id proteins antagonise the functional properties of DNA-binding, basic heli x-loop-helix transcription factors. Id proteins inhibited cell differentiat ion in various model systems, both in vitro and in vivo. They are transcrip tionally and posttranscriptionally regulated during cell cycle progression and promote cell proliferation. In order to establish the molecular and fun ctional properties of Id4, we analysed structure, chromosomal localisation and expression of the murine Id4 gene. Sequence analysis indicated that the Id4 gene consists of three exons. Multiple transcription start sites map a bout 300 bp upstream of the ATG translational start codon within a 30-bp re gion of the Id4 promoter, which lacks a classic TATA box. Expression of the Id4 gene results in four major transcripts, most likely generated by diffe rential use of polyadenylation sites. Abundance of the four transcripts var ies across tissues, suggesting tissue-specific regulation of polyadenylatio n and/or posttranscriptional regulation of Id4 expression. However, the Id4 gene seems to be expressed as a single protein. Id4 expression is switched on during embryogenesis between day 7.5 and 9.5 of gestation and is most a bundant in adult brain, kidney and testis. Id4 maps to chromosome 13 of the mouse. (C) 1998 Elsevier Science B.V. All rights reserved.