Changes in fucosyl-glycopeptides during early post-implantation embryogenesis in the mouse.
From embryonal carcinoma cells labeled with fucose, two main classes of glycopeptide products of Pronase digestion can be distinguished by Sephadex G-50 column chromatography: one eluted near the excluded volume and a smaller one. The large fucosyl-glycopeptides are scarcely present in differentiated cells derived from embryonal carcinoma cells (i.e., fibroblastlike cells, myoblasts, and parietal yolk-sac carcinoma). During in vitro differentiation of embryonal carcinoma cells, these large glycopeptides disappear almost completely. The small glycopeptides were analyzed by paper electrophoresis, concanavalin A-Sepharose affinity chromatogaphy, and digestion with an endoglycosidase. The major components of these glycopeptides from embryonal carcinoma cells appear to be different from complex glycopeptides known to occur in adult cells. The glycoptide pattern of mouse preimplantation embryos resemblestIht of embryonal carcinoma cells. These results suggest that the carbohydrate profile changes fundamentally during early stages of mammalian development. Mouse teratocarcinoma is especially useful for studying certain aspects of early mammalian development. The stem cells of teratocarcinoma, known as embryonal carcinoma (EC) cells, resemble those of early embryos and can differentiate into a variety of cell types (1, 2). EC cells can be obtained in large amounts, and thus provide a suitable material for biochemical and immunological analysis. Immunological studies of EC cells have already allowed the detection of cell surface antigens common to normal early embryonic cells (3). This communication deals with differences between carbohydrate moieties of glycoproteins from EC cells and those from EC-derived differentiated cells. Carbohydrate moieties of glycoproteins are assumed to play an important role in cellular differentiation through cell surface interactions. Significant differences in the number of receptor sites for various lectins have already been observed between EC and differentiated cells, as well as during in vitro differentiation of EC cells (4, 5). Thus, carbohydrate moieties of glycoproteins may be expected to undergo significant alterations during the early stages of mammalian development. MATERIALS AND METHODS Cell Culture and Labeling with Radioactive Fucose. EC cells and EC-derived differentiated cells (Table 1) were cultured in Falcon tissue culture dishes in Dulbecco's modified Eagle's medium containing 15% fetal calf serum at 370 in an atmosphere of 12% CO2 (8). For F941 cells, the dishes were coated with gelatin (6). For PYS-2 cells, only 5% fetal calf serum was used. All cells were routinely tested for mycoplasma contamination; none was found. For labeling with radioactive sugars, the cells were plated in 10-cm tissue culture dishes. After 24 hr, when the cells reached exponential growth phase, 50 gCi of [6-3H]fucose (10-25 Ci/mmol, Commissariat a l'Energie Atomique) was added to each dish. The cells were cultured for 24 hr, washed once with Earle's solution lacking Mg2+ and Ca2 , and harvested from tissue culture dishes by EDTA Table 1. Relationship between EC cells and EC-derived differentiated cells