Glycosphingolipids are essential for intestinal endocytic function

Glycosphingolipids (GSLs) constitute major components of enterocytes and were hypothesized to be potentially important for intestinal epithelial polarization. The enzyme UDP-glucose ceramide glucosyltransferase (Ugcg) catalyzes the initial step of GSL-biosynthesis. Newborn- and adult mice with enterocyte specific genetic deletion of the gene Ugcg were generated. In newborn mutants lacking GSLs at day P0, intestinal epithelia were indistinguishable from those in control littermates displaying an intact polarization with regular brush border. However, those mice were not able to absorb nutritional lipids from milk regularly. Between postnatal days 5 to 7 severe defects in intestinal epithelial differentiation occurred accompanied with impaired intestinal uptake of nutrients. Villi of mutant mice became stunted and enterocytes lacked brush border. The defects observed in mutant mice caused diarrhoea, malabsoption, and early death. In the present study we show that GSLs are essential for enterocyte resorptive function but primarily not for polarization; GSLs are required for intracellular vesicular transport in resorption-active intestine.