Changes in keratin expression during fetal and postnatal development of intestinal epithelial cells

Abstract

We have investigated keratin expression in fetal, newborn and adult rat intestines by immunofluorescence staining, immunoblotting of two-dimensional gels and Northern blot analysis of total cellular RNAs. Keratin-type intermediate filaments, composed predominantly of keratin no. 19, were observed already in the undifferentiated stratified epithelium present at 15-16 days of gestation. The marked maturation and differentiation of the epithelium taking place at 18-19 days of gestation was characterized by the appearance of the differentiation-specific keratin no. 21 and by a significant increase in the relative amount of keratin no. 8. The keratin pattern typical of adult villus cells became established at the time of birth, and was marked by a considerable increase in the complexity of the keratin-related polypeptides detected on two-dimensional gels, indicative of extensive post-translational modification of all keratins. Starting at 20 days of gestation there was a major increase in the relative abundance of mRNAs coding for keratin nos. 8, 19 and 21; in contrast, the relative amount of keratin no. 18 mRNA reached a peak shortly after birth and declined to very low levels in adult intestine. These results demonstrated marked changes in keratin expression and post-translational processing taking place at key stages of intestinal development. The appearance of keratin no. 21 in coincidence with the formation of an adult-type brush border and terminal web would be consistent with it having an important role in the organization of the intermediate filament network in the apical cytoplasm of the differentiated intestinal cells.

Quantitative rather than qualitative differences in gene expression predominate in intestinal cell maturation along distinct cell lineages

“…Intermediate filaments are critical for cell integrity and response to mechanical stress; they are flexible, a property due to the viscoelastic and structural features of keratins [48]. However, these characteristics are not equivalent among all the keratin members as inferred from keratin substitution experiments in transgenic mice [49] and developmental studies [50,51], suggesting that individual keratins play specific roles in certain cell types. Thus, CK19 intermediate filaments, which have been documented to respond to stimuli inducing exocytosis [52], may play a role unique to the functional features of goblet cells.…”

Developmental, Nutritional, and Hormonal Regulation of the Pancreatitis-Associated Protein I and III Gene Expression in the Rat Small Intestine

“…l), when marked structural and functional changes are known to occur in association with weaning (19). There are several examples in the literature of genes expressed in rat small intestine whose patterns of expression during development are similar (19)(20)(21)(22)(23). Most of them reach maximal expression between the 4th and 5th weeks of postnatal development, which is also the case for PAP I and PAP 111.…”

Expression of Mucins and Cytokeratins in Primary Carcinomas of the Digestive System

“…In other words, the colon cancers can be classified into the left colon, the right colon, and the rectum. The fact that among these 11 antibodies, 2 or 3 specific antibodies were associated with organ locations is assumed to be related to the expression periods of the fetus according to organic development (17,18,23,24).…”

“…Until now, 20 different subtypes of cytokeratins have been classified and numbered, based on their molecular weight and isoelectric pH (14 -16). The expression pattern of cytokeratins is dependent on the embryonic development and the degree of cellular differentiation (17,18). Because the expression of the cytokeratins is usually preserved in neoplastic cells, the use of specific antibodies is of value for determining the origin of metastatic carcinomas (2).…”