Background & aims: Cell-laminin interactions are principally mediated by specific membrane receptors of the integrin family. The integrin alpha7beta1 is one of them. Its expression in the intestine has not yet been investigated although it appears to be a key element in muscle cell differentiation. In this study, the expression of its three known isoforms has been analyzed in developing and adult small intestine and in intestinal cell lines.
Methods: The expression of the integrin alpha7beta1 was analyzed by indirect immunofluorescence, Western blotting, immunoprecipitation, and reverse-transcription polymerase chain reaction.
Results: The alpha7B isoform, but not the alpha7A and C isoforms, was detected in intestinal epithelial cells. In vivo, the presence of the alpha7B subunit was closely paralleled with (1) acquisition of differentiation characteristics during development and along the crypt-villus axis in the adult small intestine and (2) loss of enterocytic functions in the re-differentiated colonic epithelium. In vitro, the expression of alpha7B was also shown to correlate with the acquisition of enterocytic functions. In Caco-2 cells, the alpha7Bbeta1 integrin was found transiently up-regulated at the onset of sucrase-isomaltase expression.
Conclusions: Taken together, these results suggest that alpha7Bbeta1 expression is correlated with human intestinal cell differentiation.