Genomic organization, chromosomal localization, and promoter analysis of the mouse Mail gene

The Mail (molecule possessing ankyrin repeats induced by lipopolysaccharide) protein is a member of the IkappaB family. It has six ankyrin repeats that are conserved in other IkappaB proteins, such as IkappaB-alpha and Bcl-3. Mail mRNA expression is induced rapidly following lipopolysaccharide (LPS) injection, most notably in the spleen, lung, and lymph nodes of mice, where immune cells, such as lymphocytes and macrophages, are abundant. In this study, we cloned and characterized the Mail gene. The isolated genomic clones span approximately 30 kb and encompass the entire gene. Comparisons with Mail cDNA revealed that the Mail gene consists of 14 exons. Several splice junctions encoding ankyrin repeats are conserved among Mail and other IkappaB family genes. Southern hybridization showed that Mail is a single-copy gene. Using fluorescence in situ hybridization analysis, mouse and rat Mail genes were mapped to Chromosome (Chr) 16C1.2-C1.3 and Chr 11q21.1, respectively. Primer extension determined the transcription start site of Mail. Sequence analysis of the proximal promoter region revealed the presence of a TATA box and putative transcription factor-binding sites, such as those for NF-kappaB and NF-IL6. This region is sufficient to drive high-level reporter gene expression in LPS-stimulated transfected cells.