Sequence analysis of a Hoxa4-Hoxa5 intergenic region including shared regulatory elements.

The dynamic patterns of Hox gene expression are generated by a combination of regulatory elements differentially controlling Hox gene transcription in a spatio-temporal and tissue-specific fashion. Regulatory elements can either be exclusive for a particular gene, shared by neighboring Hox genes, or be competed for by different promoters. Our interest in Hoxa5 gene function and regulation have led us to localize Hoxa5 cis-acting regulatory elements in the intergenic region between the Hoxa4 and Hoxa5 genes and involved in Hoxa5 organ expression. Mapping of the region and sequence analysis revealed some discrepancies with a previously published sequence. Here, we report an additional DNA fragment of 282 base pairs that possesses high homology with the human HOX sequence, and contains potential binding sites for trans-acting factors.