Retinoid absorption and storage is impaired in mice lacking lecithin:retinol acyltransferase (LRAT).
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O'Byrne SM, Wongsiriroj N, Libien J, Vogel S, Goldberg IJ, Baehr W, Palczewski K, Blaner WS
Retinoid absorption and storage is impaired in mice lacking lecithin:retinol acyltransferase (LRAT).
J Biol Chem. 2005 Oct 21;280(42):35647-57. Epub 2005 Aug 22.
- PubMed ID
- 16115871 [ View in PubMed]
- Abstract
Lecithin:retinol acyltransferase (LRAT) is believed to be the predominant if not the sole enzyme in the body responsible for the physiologic esterification of retinol. We have studied Lrat-deficient (Lrat-/-) mice to gain a better understanding of how these mice take up and store dietary retinoids and to determine whether other enzymes may be responsible for retinol esterification in the body. Although the Lrat-/- mice possess only trace amounts of retinyl esters in liver, lung, and kidney, they possess elevated (by 2-3-fold) concentrations of retinyl esters in adipose tissue compared with wild type mice. These adipose retinyl ester depots are mobilized in times of dietary retinoid insufficiency. We further observed an up-regulation (3-4-fold) in the level of cytosolic retinol-binding protein type III (CRBPIII) in adipose tissue of Lrat-/- mice. Examination by electron microscopy reveals a striking total absence of large lipid-containing droplets that normally store hepatic retinoid within the hepatic stellate cells of Lrat-/- mice. Despite the absence of significant retinyl ester stores and stellate cell lipid droplets, the livers of Lrat-/- mice upon histologic analysis appear normal and show no histological signs of liver fibrosis. Lrat-/- mice absorb dietary retinol primarily as free retinol in chylomicrons; however, retinyl esters are also present within the chylomicron fraction obtained from Lrat-/- mice. The fatty acyl composition of these (chylomicron) retinyl esters suggests that they are synthesized via an acyl-CoA-dependent process suggesting the existence of a physiologically significant acyl-CoA:retinol acyltransferase.
DrugBank Data that Cites this Article
- Drug Carriers
Drug Carrier Kind Organism Pharmacological Action Actions Vitamin A Retinol-binding protein 5 Protein Humans UnknownBinderDetails