A marked increase of fucosylation of glycoproteins in IMR-90 human diploid fibroblasts during senescence in vitro.

Possible changes of glycoproteins in IMR-90 human embryonic lung fibroblasts during senescence in vitro were studied by the metabolic labeling technique using radioactive precursors for carbohydrate moieties of glycoproteins. IMR-90 fibroblasts at three different population doubling level (PDL) were incubated with [3H]fucose and [3H]glucosamine for various periods of time. The radioactively labeled glycoproteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and fluorography. The results indicated a marked increase, by more than eight-fold on per mg protein basis, of labeling by [3H]fucose in old IMR-90 fibroblasts (PDL = 45) as compared to young (PDL = 22) and middle-age (PDL = 30) IMR-90 fibroblasts. In contrast, no significant difference in [3H]glucosamine labeling was observed in young and old IMR-90 cells.