Effect of Tunicamycin on the Biosynthesis of Human Fibroblast Collagenase

Abstract

It is generally accepted that collagenase from human fibroblast cultures consists of two proenzymes (M_r 60,000 and 55,000) and two active forms (M_r 50,000 and 43,000). We demonstrated previously that epidermal growth factor (EGF) as well as a number of other growth factors induced the secretion of procollagenase (M_r 60,000, M_r 55,000) into the medium of human fibroblast cultures (Chua et al., 1985). In the presence of tunicamycin and EGF, the secretion of the larger form of procollagenase was suppressed preferentially with concomitant appearance of a new band, M_r 40,000. This M_r 40,000 band could be specifically immunoprecipitated by antibody raised against human collagenase. By two-dimensional peptide mapping, the M_r 40,000 material appeared to have similar composition as the M_r 60,000 band. In a time course study, the M_r 55,000 procollagenase band was the earliest protein to appear in the medium after 1 hour labeling with [³⁵S] -methionine. The M_r 60,000, 50,000 and 43,000 bands appeared after a 2 hour labeling period. Our results indicate that human collagenases are glycosylated proteins and are synthesized via the dolichol phosphate pathway.