Altered glycosaminoglycan production in cultured osteogenesis-imperfecta skin fibroblasts

Abstract

Collagen and glycosaminoglycan syntheses were studied in skin fibroblasts cultured from patients with osteogenesis imperfecta (OI) and from age-matched controls. Collagen synthesis (measured as protein-bound [3H]hydroxyproline) was decreased in all four OI cell lines studied in the present experiments, comprising 16-24% of total protein synthesis (40% in normal cells). Hyaluronic acid production in OI skin fibroblasts per cell was higher than in age-matched controls, but the production of sulphated glycosaminoglycans was at the normal level. Thus the ratio of the hyaluronic acid and sulphated-glycosaminoglycan radioactivities was markedly higher in OI cultures than in control cultures, especially at the exponential phase of growth where the synthesis of hyaluronic acid was highest. Hyaluronic acid in OI had a normal molecular weight when determined by gel filtration on Sepharose 2B. The removal of high-molecular-weight hyaluronic acid from the medium by hyaluronidase had no effect on the rate of collagen secretion in OI cell line 1 (A.T.C.C. 1262), in which the rate of collagen secretion was lowest.