Biosynthesis and Expression of Gangliosides During Differentiation of Chick Embryo Retina Cells In Vitro

Abstract

Cells from neural retina from 7-day chick embryos were cultured on polylysine-coated dishes up to 7 days. The small, round-shaped cells at seeding differentiated progressively, and after 4 days in vitro the majority had enlarged bodies and abundant processes. The content of protein and DNA was essentially unchanged during the entire period of culture. The incorporation of radioactivity from [3H]glucosamine into gangliosides declined slightly, reaching about 65% of the initial values at the end of the culture period. The proliferating activity measured by the incorporation of [3H]thymidine into DNA decreased to 10% or less of the initial value after 3 days in vitro. Almost at the same chronological times as in ovo, the synthesis of GD3 and of a ganglioside partially identified as GT3 decreased from 70 and 19% of the total incorporation into gangliosides in the first 20 h of culture to about 7 and 5%, respectively, after 3 days in vitro. Conversely, the synthesis of GD1a increased from about 6% at the beginning to about 70% at the end of the culture times. Immunocytochemical analyses of the expression of gangliotetraosyl gangliosides in cultured cells showed that these gangliosides appeared in the bodies and processes of cells having neuronal morphology; very little immunostaining of the scarce flattened cells, probably Müller cells, was found. The results indicate that the changes in ganglioside metabolism, which lead to decreased synthesis of gangliosides lacking the galactosyl-N-acetyl-galactosaminyl disaccharide end and to increased synthesis of gangliotetraosyl gangliosides, occur in cells that in culture differentiate into neurons.

GD3 and GM2 synthase activities in rat testes during the period of sexual development

“…In embryonic rat brain, major GD 3 synthase activity has been observed during early embryonic stages, while an increase in GM 2 synthase activity has been shown to occur during later embryogenesis and adulthood (6,7). Similar results have been observed in embryonic chick retina and embryonic human brain (5,8).…”

“…Modifications in the ganglioside pattern during development may be associated with correspoding changes in the activities of specific glycosyltransferases. In the chick embryo retina system and the mammalian brain developmental changes in ganglioside composition correlate with variations in the activities of the key ganglioside glycosyltransferases: GD 3 and GM 2 synthases (5)(6)(7)(8). Gamallo and Bernard (9) demonstrated that rat testes gangliosides show a pattern of increasing complexity with aging.…”

Internalization of the inhibitor of the N‐acetylgalactosaminyltransferase by chicken embryonic retina cells: Reversibility of the inhibitor effects

“…This ratio was substantially higher than that reported by Quiroga et al (1990). It might be noted that in the present experiment the labeled glucosamine was added at the second day in vitro, and in the experiment by Quiroga et al it was at the fourth day, and in that period a dramatic change in the relationship between GD3 and GDla synthesis occurs in normal cells: the GD3 synthesis decays fivefold and that of GDla increases twofold (Panzetta et al, 1987).…”

GD3 ganglioside is prevalent in fully differentiated neurons from rat retina

“…From our data and data taken from other authors (see Table II), we calculated that the pathway "a" to pathway "b" ganglioside ratio was lower in mammalian retina than in chick retina and chick, rat, and human brain. We have already suggested (Panzetta et al, 1987;Maccioni et al, 1989) that the high proportion of pathway "a" gangliosides in the adult chick retina was probably due to the low activity of GD3 synthetase coexisting with high activities of the GM2 and GMl synthetases, which lead to the conversion of GM3 into gangliosides of the gangliotetraosylceramide series. We would predict that the balance of GD3iGM2 (and GM 1) synthetase activities would favor CD3 synthetase in the mammalian retinas, although this issue must be further investigated.…”