9-CIS-RETINOIC ACID ENHANCES FATTY ACID-INDUCED EXPRESSION OF THE LIVER FATTY-ACID-BINDING PROTEIN GENE

The role of retinoic acids (RA) on liver fatty acid-binding protein (L -FABP) expression was investigated in the well differentiated FAO rat hepatoma cell line, 9-cis-Retinoic acid (9-cis-RA) specifically enhanc ed L-FABP mRNA levels in a time-and dose-dependent manner, The higher induction was found 6 h after addition of 10(-6) M 9-cis-RA in the med ium, RA also enhanced further both L-FABP mRNA levels and cytosolic L- FABP protein content induced by oleic acid, The retinoid X receptor (R XR) and the peroxisome proliferator-activated receptor (PPAR), which a re known to be activated, respectively, by 9-cis-RA and long chain fat ty acid (LCFA), co-operated to bind specifically the peroxisome prolif erator-responsive element (PPRE) found upstream of the L-FABP gene, Ou r result suggest that the PPAR-RXR complex is the molecular target by which 9-cis-RA and LCFA regulate the L-FABP gene. (C) 1997 Federation of European Biochemical Societies.