The Biochemical journal

Regulation of expression of the human fructose transporter (GLUT5) by cyclic AMP.

PMID 8037665


The effect of cyclic AMP on the expression of the fructose transporter, GLUT5, was studied in Caco-2 cells, a human colon cancer cell line that differentiates spontaneously in culture into cells with the properties of small intestine enterocytes. Treatment of differentiated Caco-2 cells with 50 microM forskolin, which stimulates adenylate cyclase and raises intracellular cyclic AMP levels, increased fructose uptake 2-fold and raised GLUT5 protein and mRNA levels 5- and 7-fold respectively. The increased GLUT5 mRNA levels in forskolin-treated cells are a result of stabilization of GLUT5 mRNA in these cells and increased transcription. The effect of cyclic AMP on GLUT5 transcription was assessed by measuring the activity of human GLUT5 promoter-reporter gene constructs in forskolin-treated differentiated Caco-2 cells. The results showed that forskolin stimulated the activity of the GLUT5-reporter gene constructs and this stimulatory effect was mediated by cis-acting regulatory sequences.