Identification of a purine-rich intronic enhancer element in the mouse eosinophil-associated ribonuclease 2 (mEar 2) gene.

The Mus musculus eosinophil-associated ribonuclease (mEar) gene cluster includes multiple distinct coding sequences that are highly divergent orthologs of the human eosinophil ribonucleases, eosinophil-derived neurotoxin (EDN/RNase 2) and eosinophil cationic protein (ECP/RNase 3). We present a transcriptional analysis of the gene encoding mEar 2, the only member of this cluster with a well-defined expression profile. In this work, we demonstrate that the presence of non-coding exon 1 and the intron in tandem with a 361-bp 5' promoter of mEar 2 results in enhanced reporter gene expression, as much as 6-to 10-fold over the activity observed with the 5' promoter alone.