Structure and expression of the mouse angiotensinogen gene

Angiotensinogen is a precursor of the multifunctional octapeptide hormone, angiotensin II. We have isolated the overlapping clones containing angiotensinogen gene locus from C57BL/6 mouse genomic DNA library and analyzed them by restriction enzyme mapping. The gene exhibited a structural organization similar to those of the human, rat and balb/c mouse angiotensinogen genes. Using a genomic DNA fragment of the mouse angiotensinogen gene as a probe, we have investigated the tissue distribution of angiotensinogen messenger RNA (mRNA) in C57BL/6 mouse. The angiotensinogen mRNA was highest in the liver and detectable in such tissues as brain, kidney, submandibular gland, ovary and heart. However, it was undetectable in lung and spleen under the condition used. Optimal alignments of the 5'-flanking regions among the human, rat and mouse angiotensinogen genes disclosed several deletions in the mouse sequence. To assay the promoter activity, the 5'-flanking region of the mouse angiotensinogen gene was ligated to the bacterial chloramphenicol acetyltransferase (CAT) gene, then transfected into different cultured cells. The angiotensinogen gene sequences elicited preferential expression of CAT activity when introduced into HepG2 cells derived from liver and 293 cells from kidney but not in HeLa cells from uterus, suggesting the presence of a cell type-specific promoter within the sequences. These findings on the structure and expression of the mouse angiotensinogen gene should prove useful in studying the function and control of the angiotensin.