Development of a versatile reporter assay for studies of retinol uptake and metabolism in vivo.

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Citation

Liden M, Eriksson U

Development of a versatile reporter assay for studies of retinol uptake and metabolism in vivo.

Exp Cell Res. 2005 Nov 1;310(2):401-8. Epub 2005 Sep 8.

PubMed ID
16150442 [ View in PubMed
]
Abstract

The two isomers of retinoic acid (RA), all-trans RA and 9-cis RA, are produced in several tissues in order to allow specific control of target gene transcription. Given the high potency of these receptor ligands, it seems likely that the cellular uptake and metabolic activation of the precursor, retinol (vitamin A), should be a highly regulated process. Several retinol dehydrogenases and components involved in the downstream events have been identified and partially characterized. However, less is known about the cellular uptake of retinol, and the isomerase activity giving rise to the 9-cis and 11-cis branches of the pathway. In this work, we show that the 9-cis RA biosynthesis pathway can be fully reconstituted in cultured HEK293A cells expressing a reporter system, including an endogenous isomerase activity converting all-trans retinol into 9-cis retinol. This assay allows for functional studies of known components, as well as screening for yet unidentified genes involved in the pathway. In addition to free all-trans retinol, we find that these cells can take up retinol from plasma retinol binding protein (RBP) by a mechanism that can be efficiently inhibited by blocking antibodies, suggesting that the uptake may involve a cellular receptor. We also demonstrate that overexpression of CRBPI can drive the accumulation of intracellular retinol from unbound retinol added to the medium. Thus, this versatile cellular assay can be used to study several aspects of retinol uptake and metabolism in vivo.

DrugBank Data that Cites this Article

Drug Carriers
DrugCarrierKindOrganismPharmacological ActionActions
Vitamin ARetinol-binding protein 4ProteinHumans
Unknown
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