Altered protein glycosylation and procollagen to collagen conversion in human fibroblasts

Skin fibroblasts, from a 9-year-old girl with an apparent heritable disorder of connective tissue, were cultured in vitro. The biosynthesis of the extracellular matrix glycoproteins, procollagens, and fibronectin was studied using radioactively labeled sugars and amino acids. Glycoproteins synthesized and secreted into the growth medium were found to be only partially glycosylated and the extracellular limited proteolytic conversion of procollagen type I to collagen was impaired, with procollagen chains accumulating in the growth medium. These biosynthetic alterations have not been previously reported in human skin fibroblasts, but similar findings have been described in tunicamycin-treated chick fibroblasts.