The disorder of hyaluronic acid metabolism in cultured skin fibroblasts derived from a patient with the Hurler syndrome

Connective tissue activation. XXVII. The behavior of skin fibroblasts from patients with scleroderma

Four normal (NF) and 4 scleroderma skin fibroblast (SF) strains were compared with respect to 1) basal 14C-glucosamine and 35SO4-labeled glycosaminoglycan (GAG) synthesis, 2) responsiveness to autacoid mediators, and 3) performance following maximal stimulation. Under basal conditions, SF synthesized and secreted 2-3 times more radioactive hyaluronic acid than the NF (P less than 0.001); molecular volume by gel chromatography was similar and suggested a high molecular weight product. SF were essentially as responsive to normal lymphoid and platelet factors as were NF. No consistent qualitative or quantitative differences in sulfated GAG synthesis were noted between the 2 groups of cells. Incubation of NF and SF with a false "core protein" such as p-nitrophenyl-beta-D-xyloside suggested that synthesis of the core protein was rate limiting; SF and NF were equally facile in SO4-GAG chain synthesis in the presence of a beta-xyloside. SF appear to retain in vitro a partially activated state for many generations, at least with respect to hyaluronic acid synthesis.

Altered glycosaminoglycan production in cultured osteogenesis-imperfecta skin fibroblasts

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.

Synthesis and degradation of hyaluronic acid in the cultured fibroblasts of Marfan's disease

Increased amounts of hyaluronic acid accumulate in fibroblasts cultured from patients with Marfan's disease, an autosomal dominant disorder. In the recessive Hurler's disease, the storage of glycosaminoglycan (GAG) is due to impaired degradation. This study examines the kinetics of GAG accumulation in Marfan's disease in order to determine whether the mechanism of accumulation differs from that in Hurler's disease.Marfan-derived fibroblasts incorporated [(14)C]acetate or [(14)C]glucosamine into GAG to a level 4-6 times greater than control fibroblasts. Sugar analyses, electrophoretic mobility, and enzyme susceptibility studies showed that the isolated material was hyaluronic acid. There were no differences in activity of a variety of glycosidases between Marfan and control fibroblasts, nor were there differences in the ability to degrade prelabeled hyaluronate by cell-free extracts. Finally, chase experiments showed parallel rates of loss of labeled GAG from control fibroblasts and fibroblasts from Marfan patients. It appears that hyaluronic acid was accumulating in greater amounts in the fibroblasts from patients with Marfan's disease because of a greater rate of synthesis as opposed to a decreased rate of breakdown.

Biochemical studies on the sulphated glycosaminoglycan fraction of skin fibroblasts cultured from a patient with the Hurler syndrome

1. The metabolism of the sulphated glycosaminoglycan fraction in cultured skin fibroblasts derived from a patient with the Hurler syndrome and from a normal subject was studied. Two labelled precursors, Na(2) (35)SO(4) and d-[2-(3)H]glucose, were used and their intracellular fates during uptake and ;chase' periods were assessed after separation of sulphated glycosaminoglycans from hyaluronic acid. After 4 or 8h of exposure to culture medium containing both labels, [(35)S]sulphate incorporation into the sulphated glycosaminoglycan fraction was twofold greater in Hurler-syndrome cells than in normal cells. At the same time, the rate of incorporation of [(3)H]glucose into the sulphated glycosaminoglycan fraction was approximately the same for both cell types. Consequently, an increased (35)S/(3)H ratio (nmol of [(35)S]sulphate incorporated/nmol of [(3)H]glucose incorporated) was observed for Hurler-syndrome cells compared with normal cells. 2. The results of ;chase' experiments revealed that although the expected loss and relative retention of labelled sulphate occurred in the sulphated glycosaminoglycan fraction of normal and Hurler-syndrome cells, both cell types retained all of their radioactivity derived from [(3)H]glucose. 3. After 34h exposure to a ;corrective-factor' preparation from urine, the sulphated glycosaminoglycan content (as hexosamine and [(35)S]sulphate) of the Hurler-syndrome cells approached normal values. At the same time, there was an increase in specific radioactivity of ;corrected' Hurler-syndrome cells.