earticle

영어

In this study, alterations in glycan chains, especially in sialylation, of the glycoproteins in brain cortex tissues during early post-natal development of E18 and post-natal rats (1-day, 4-week and 8-week-old) were investigated. The lectin histochemistry using sialic acid specific lectins, SNA and MAA, lectin blotting of total proteins, and total N-glycan structure analysis showed that both α2,3- and α2,6-linked sialic acid residues of the several proteins on the surface of cortex tissues are significantly expressed in cortex tissues of 1-day-old rats and that, as the rats grow up to young adult (8-week-old), their expression is markedly down-regulated. The activity of sialidase, which catalyzes the cleavage of terminal sialic acids of glycan chain of glycoproteins, significantly increased as rats grow up. Interestingly, however, western blotting analysis of sialidase and α2,3- and α2,6-sialyltransferase showed that there was no significant difference in sialidase protein level in between E18 and 8-week-old young adult rat brains, whereas the protein levels of α2,3- and α2,6-sialyltransferases gradually decreased. These results strongly suggest that the decreased level of α2,3- and α2,6- sialylation on N-glycans would correlate with the up-regulation of enzyme activity, not the protein level of the sialidase, and also with the down-regulation of both α2,3- and α2,6-sialyltranferase protein level. The results suggest that the observation on the developmental stage-dependent decrease in α2,3 and α2,6 sialylation on glycoproteins could be attributed to a certain post-translational regulation of sialo-enzymes. Elucidating the mechanism and function of these regulation events would be very important for better understanding the normal development of brain tissues and also to effectively treat neurodegenerative diseases. Furthermore, the specific roles of those glycoproteins, observed in this study, which showed significant degree of age-dependent alterations in glycosylation and sialylation remain to be elucidated and these sialoglycoproteins may provide new, even specific, regulatory molecules in the early post-natal development of rat brain nervous system.