Background: In children, lactase and sucrase-isomaltase are essential intestinal glycohydrolases, and insufficiency of either enzyme causes diarrhea and malnutrition. Little is known about the regulation of lactase and sucrase-isomaltase expression in the duodenum during childhood. In this study, the mechanisms of regulation of duodenal expression of both enzymes were examined in a study population with ages ranging from 1 to 18 years. Methods: Duodenal biopsy specimens from 60 white children were used to analyze tissue morphology and to quantify lactase and sucrase-isomaltase mRNA and protein. Results: Among healthy subjects, high interindividual variability was noted in both mRNA and protein levels for lactase and sucrase-isomaltase. Lactase mRNA level per subject did not correlate with sucrase-isomaltase mRNA level and thus appeared independent. Both lactase and sucrase-isomaltase protein levels correlated significantly with their respective mRNA levels. For each enzyme, a significant inverse correlation was observed between the degree of viiius atrophy and mRNA levels. Aging from 1 to 18 years did not result in significant changes in mRNA or protein levels of either enzyme. Immunostaining patterns within the duodenal epithelium for lactase differed from sucrase-isomaltase in adjacent sections, illustrating independent regulation at the cellular level. Conclusions: In the duodenum of white children, lactase and sucrase-isomaltase seem primarily regulated at the transcriptional level. The expression of each enzyme in the intestinal epithelium is regulated by an independent mechanism. Lactase and sucrase- isomaltase exhibit stable mRNA and protein levels in healthy children as they grow to adulthood. Mucosal damage affected levels of both enzymes negatively.

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Journal of Pediatric Gastroenterology and Nutrition
Department of Pediatrics

van Beers, E.H, Rings, E.H.H.M, Taminiau, J.A, Heymans, H.S.A, Einerhand, A.W.C, Dekker, J, & Büller, H.A. (1998). Regulation of lactase and sucrase-isomaltase gene expression in the duodenum during childhood. Journal of Pediatric Gastroenterology and Nutrition, 27(1), 37–46. doi:10.1097/00005176-199807000-00007