DEVELOPMENTAL-CHANGES IN INTESTINAL GLYCOSYLATION - NUTRITION-DEPENDENT MULTIFACTOR REGULATION OF THE FUCOSYLATION PATHWAY AT WEANING TIME

Developmental changes in the fucoglycoproteins of the intestinal brush -border membranes were determined by lectin affinoblotting after elect rophoresis. Whereas only two alpha(1-6)-fucoglycoproteins were detecte d in brush-border membranes from suckling rats, a large number of N-fu coglycoproteins with alpha(1-2)- and/or alpha(1-6)-linked fucose resid ues were detected in rat membranes after weaning. Dietary manipulation s at weaning time were used to investigate the effect of nutritional f actors in the development of fucosylation in the small intestine of pr olonged-nursed rats fed with milk (a high-fat, low-carbohydrate diet) compared to rats weaned normally with a standard high-carbohydrate die t. The fucose content of the mucosa glycoproteins was lower in 22-day- old prolonged-nursed rats than in 22-day-old rats weaned normally with the standard diet. The appearance of fucoglycoproteins in the brush-b order membranes, which was delayed by prolonged nursing, was accompani ed by a concomitant delay in the increase of intestinal fucosyl-transf erase activity and in the decrease of GDP-fucose substrate breakdown. The developmental decrease in the activity of the inhibitory protein w hich regulates the fucosyl-transferase activity was also delayed by pr olonged nursing. The intestinal fucosylation of brush-border membrane glycoproteins (which include many digestive enzymes) displayed ontogen ic changes on which were superimposed dietary influences at the time o f weaning. The complete maturation of the brush-border membrane glycop roteins, and particularly their terminal fucosylation, is a developmen tal event which thus seems to be strongly influenced by the manipulati on of nutritional factors during the weaning period.