Rat collagenase. Cloning, amino acid sequence comparison, and parathyroid hormone regulation in osteoblastic cells.

Abstract

We have isolated clones for rat collagenase from a rat osteoblastic cell cDNA library. These clones have been sequenced and the amino acids deduced. The calculated molecular weight is 51,352 for the proenzyme and 42,229 for the active enzyme. The deduced amino acid sequence was compared to those previously reported for: 1) human collagenase, 2) rat transin 1 (stromelysin), 3) human stromelysin, and 4) rabbit collagenase. The number of amino acids conserved was 47, 47, 50, and 47%, respectively. We also compared the collagenase mRNA and protein in different rat cells (osteoblast, uterine smooth muscle, synovial fibroblast) and determined that in rat uterine cells the message is slightly larger, although collagenase protein in all three cell types was identical in size. Parathyroid hormone dramatically induces the 2.9-kilobase collagenase mRNA in the rat osteoblastic cells, UMR 106-01. Nuclear run-on studies in UMR 106-01 cells demonstrated a 4-8-fold induction in the rate of synthesis of collagenase mRNA at 2 and 4 after parathyroid hormone treatment, with steady state levels of mRNA increased 100-fold at 4 h. Thus, parathyroid hormone regulation of the collagenase gene in UMR 106-01 cells is in part transcriptional.