A COMPLETE EPITHELIAL ORGANIZATION OF CACO-2 CELLS INDUCES I-FABP ANDPOTENTIALIZES APOLIPOPROTEIN GENE-EXPRESSION

The culture of Caco-2 cells on plastic support impairs the expression of several genes involved in lipid metabolism. We describe culture con ditions that permit the expression of the I-FABP gene and better expre ssion of the apolipoprotein A-I, C-III, and A-IV genes. Basal lamina d eposited on filters as well as the nature of nutrients on the apical s ide differentially modulated mRNA expression of I-FABP, APOBEC-1, and apolipoprotein genes, Growing cells on a filter led to functional pola rization, illustrated by a secretion of apo B at the basal side, which induced the expression of the I-FABP, APOBEC-1, and apo A-IV genes an d highly increased the expression of the apo C-III gene, Moreover, bas al lamina deposited on the filter enhances the mRNA expression of apo A-I. Apo C-III and A-IV mRNA levels were decreased when cells were gro wn on a filter covered with basal lamina in the presence of a medium d eprived of protein and lipid on the apical side, whereas these conditi ons had no effect on I-FABP, apo A-I, and APOBEC-1 mRNA levels, The ad dition of lipid micelles on the apical side had various effects, accor ding to the genes. Caco-2 cells cultured under the conditions describe d here closely resembled enterocytes and represent a useful tool for s tudying the regulation of genes involved in lipid metabolism. (C) 1997 Academic Press.