Characterization of the cell adhesion molecules L1, N-CAM and J1 in the mouse intestine.

To gain insight into the cellular and molecular mechanisms underlying epithelial cell surface interactions in the adult mouse intestine, we have characterized the cell adhesion molecules L1, N-CAM and J1 by immunocytological, biochemical and cell biological methods. Whereas N-CAM and J1 expression was found to be confined to the mesenchymal and neuroectodermally-derived parts of the intestine, L1 was localized in the proliferating epithelial progenitor cells of crypts, but not in the more differentiated epithelial cells of villi. L1 was detected in crypt cells by Western blot analysis in the molecular forms characteristic of peripheral neural cells, with apparent mol. wts of 230, 180 and 150 kd. Aggregation of single, enriched crypt, but not villus cells, was strongly inhibited in the presence of Fab fragments of polyclonal L1 antibodies. These observations show that L1 is not confined to the nervous system and that it may play a functional role in the histogenesis of the intestine in the adult animal.