Open AccessBiosynthesis of intestinal microvillar proteins
Author(s) -
DANIELSEN E. Michael
Publication year - 1984
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1984.tb08606.x
Subject(s) - crypt , aminopeptidase , dexamethasone , biology , explant culture , enzyme , epithelium , microbiology and biotechnology , small intestine , methionine , medicine , endocrinology , biochemistry , chemistry , amino acid , leucine , in vitro , genetics
The expression of pig small‐intestinal aminopeptidase N (EC 3.4.11.2) along the crypt‐villus axis was studied in tangential sections of [ 35 S]‐methionine‐labelled, organ‐cultured explants. The only detectable molecular forms of aminopeptidase N along the crypt‐villus axis were polypeptides of M r 140000 and 166000, representing the enzyme in a transient and mature form respectively. The synthesis was at a very low level in the crypt region in experiments with labelling periods ranging from 10 min to 3 h. These findings indicate that crypt cells are not fully committed to the expression of aminopeptidase N, either in its mature or in any other immunoreactive molecular form. The expression of aminopeptidase N was markedly stimulated by dexamethasone (1 μg/ml). During labelling periods of 3 h, dexamethasone caused an approximately threefold increase in the expression of the enzyme in the crypt cells and a moderate increase of about 20% in the villus cells. Whereas the latter can possibly be ascribed to a general protective effect of dexamethasone on villus architecture, these experiments indicate that crypt cells of mucosa from adult individuals exhibit the same sensitivity to glucocorticoids as does the intestinal epithelium during the prenatal and early postnatal phase.