Studies on differentiating epithelial cells of rat small intestine. Alterations in the lipophilic part of glycosphingolipids during cell migration from crypt villus tip.

Epithelial cells of rat small intestine have been separated into three intervals of different maturity correlated to cell migration from the crypt to the villus tip. The total acid and non-acid glycosphingolipids were isolated and analysed by thin-layer chromatography. The amount of glucosylceramide an N-glycoloylneuraminosyllactosylceramide was higher, while the amount of globotriaosylceramide and tetrahexosylceramide was lower in villus tip cells (more differentiated) compared to crypt cells (less differentiated). In addition to these alterations the lipophilic composition changed, as shown by a comparison by mass spectrometry of permethylated and LiAlH4-reduced, permethylated derivatives of two of the non-acid glycolipid mixtures (crypt cells and villus tip cells). The components of ceramide were mainly trihydroxy 18:0 long-chain base (phytosphingosine) and hydroxy and non-hydroxy fatty acids. The only significant change concerned the fatty acids. In the crypt cell glycolipids the most abundant fatty acid was 20:0 non-hydroxy fatty acid. In the villus tip cells there was a relative increase of hydroxy fatty acids, with the 24:0 species in dominance. This change occurred for most glycolipids, but the fatty acids of glucosylceramide were villus tip-like already in the crypt cells. The blood group A-active tetraglycosylceramide, and probably the hematoside, did not show any alteration in the lipophilic part. The results indicate that the turnover of some glycolipids (or only their lipophilic part) is more rapid than the epithelial cell turnover.