RELATION BETWEEN INTEGRIN ALPHA-7B-BETA-1 EXPRESSION IN HUMAN INTESTINAL-CELLS AND ENTEROCYTIC DIFFERENTIATION

Background & Aims: Cell-laminin interactions are principally mediated by specific membrane receptors of the integrin family. The integrin al pha 7 beta 1 is one of them. Its expression in the intestine has not y et been investigated although it appears to be a key element in muscle cell differentiation. In this study, the expression of its three know n isoforms has been analyzed in developing and adult small intestine a nd in intestinal cell lines. Methods: The expression of the integrin a lpha 7 beta 1 was analyzed by indirect immunofluorescence, Western blo tting, immunoprecipitation, and reverse-transcription polymerase chain reaction. Results: The alpha 7B isoform, but not the alpha 7A and C i soforms, was detected in intestinal epithelial cells. In vivo, the pre sence of the alpha 7B subunit was closely paralleled with (1) acquisit ion of differentiation characteristics during development and along th e crypt-villus axis in the adult small intestine and (2) loss of enter ocytic functions in the re-differentiated colonic epithelium. In vitro , the expression of a7B was also shown to correlate with the acquisiti on of enterocytic functions. In Caco-2 cells, the alpha 7B beta 1 inte grin was found transiently up-regulated at the onset of sucrase-isomal tase expression. Conclusions: Taken together, these results suggest th at alpha 7B beta 1 expression is correlated with human intestinal cell differentiation.