Structure, Regulation and Evolution of the Genes for the Renin-Angiotensin and the Kallikrein-Kinin Systems

Expression of rat renin in mammalian cells and its purification

Rat renin cDNA was transfected into COS-7 and Chinese hamster ovary (CHO) cells and expressed under the control of the Simian Virus 40 early promoter. Conditioned media of the transfected cells showed renin activity only after trypsin treatment, suggesting prorenin was secreted into the medium. From the trypsinized serum-free culture of the transfected CHO cells active renin was purified to homogeneity by a simple three-step procedure. The active renin had similar specific activity, molecular weight, Km, pH optimum, and isoelectric point compared to native renin. The amino-terminal sequence was the same as that deduced from the renin cDNA. This suggests that the recombinant rat renin is similar to kidney renin in many respects, and is easily obtained by the present procedures.

Primary structure of a gene encoding rat T-kininogen

A gene encoding the acute-phase reactant, T-kininogen, has been isolated from a rat genomic library. The nucleotide sequence of all exons as well as of a large portion of the introns was determined. The gene, T-KG, is approximately 24 kb in length and contains 11 exons. The promoter appears to be rather unusual in that there are no consensus CCAAT or TATAA boxes or SP1-binding sites. An A-rich region present upstream of the transcription start point may function as a TATAA-equivalent sequence. In addition, several potential glucocorticoid regulatory elements and a sequence similar to the AP-1 binding site are present in the 5' region of the gene. The intron/exon boundaries in this T-KG gene are identical to those seen in the human K-kininogen gene. This is consistent with the inclusion of T-KG in the cystatin supergene family of cysteine protease inhibitors.