Disruption of the lecithin: Retinol acyltransferase gene makes mice more susceptible to vitamin a deficiency

Lecithin: retinol acyltransferase (LRAT) catalyzes the esterification of retinol (vitamin A) in the liver and in some extrahepatic tissues, including the lung. We produced an LRAT gene knock-out mouse strain and assessed whether LRAT(-/-) mice were more susceptible to vitamin A deficiency than wild type (WT) mice. After maintenance on a vitamin A-deficient diet for 6 weeks, the serum retinol level was 1.34 +/- 0.32 mu M in WT mice versus 0.13 +/- 0.06 mu M in LRAT (-/-) mice (p < 0.05). In liver, lung, eye, kidney, brain, tongue, adipose tissue, skeletal muscle, and pancreas, the retinol levels ranged from 0.05 pmol/mg (muscle and tongue) to 17.35 +/- 2.66 pmol/mg (liver) in WT mice. In contrast, retinol was not detectable (< 0.007 pmol/mg) in most tissues from LRAT (-/-) mice after maintenance on a vitamin A-deficient diet for 6 weeks. Cyp26A1 mRNA was not detected in hepatic tissue samples from LRAT (-/-) mice but was detected in WT mice fed the vitamin A-deficient diet. These data indicate that LRAT (-/-) mice are much more susceptible to vitamin A deficiency and should be an excellent animal model of vitamin A deficiency. In addition, the retinol levels in serum rapidly increased in the LRAT (-/-) mice upon re-addition of vitamin A to the diet, indicating that serum retinol levels in LRAT (-/-) mice can be conveniently modulated by the quantitative manipulation of dietary retinol.