Tissue- and cell-specific control of guinea pig cathepsin E gene expression.

Northern blotting of RNAs from normal guinea pig tissues revealed that the tissue distribution of cathepsin E mRNA was relatively limited and the highest level of the mRNA was observed in the stomach mucosa. Expression of the mRNA was also observed in the spleen, although the level was very low. These results were in good agreement with the distribution of the cathepsin E-producing cells as revealed by immunohistochemistry. In the separated fractions of dispersed mucosal cells prepared from the stomach by centrifugal elutriation, the extent of cathepsin E mRNA expression was closely correlated with the enrichment of the producing cells. In addition, both CCGG and GCGC sites within the gene region were hypomethylated to a greater extent in the producing tissues than elsewhere, reflecting specific hypomethylation in the producing cells. The observed tissue- and cell-specific transcriptional control of cathepsin E gene, which is correlated with a decreased level of methylation in the gene region, suggests that the enzyme is probably involved in specific functions of particular differentiated cells, especially those of the stomach mucosa.