A new retinoic acid receptor identified from a hepatocellular carcinoma.
Processes as diverse as growth, vision and reproduction depend on the presence of vitamin A and its metabolites (retinoids), but the molecular mechanisms which govern these diverse actions remain unclear (for reviews see refs 1,2). A crucial advance recently was the isolation of a specific nuclear receptor for retinoic acid, one of the physiologically active vitamin A derivatives. This nuclear receptor is a member of the steroid/thyroid hormone receptor family. Our analysis of an uncharacterized member of this class of intracellular receptors, encoded by a complementary DNA clone from a human placental library, has led us to discover a second retinoic acid receptor. This new receptor is expressed at high levels in a number of epithelial-type tissues. The gene for the receptor was first identified in a hepatocellular carcinoma where it surrounds a site of integration of hepatitis B virus. Activation by this virus may play a role in tumour development in liver cells, where it is normally not expressed.
Benbrook
D
D
Cancer Research Center, La Jolla Cancer Research Foundation, California 92037.
Lernhardt
E
E
Pfahl
M
M
D000595:Amino Acid Sequence; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D005796:Genes; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism*; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics*; D014176:Protein Biosynthesis; D018168:Receptors, Retinoic Acid; D014158:Transcription, Genetic; D014162:Transfection; D014212:Tretinoin / Q000378:metabolism*
D002352:Carrier Proteins; D009363:Neoplasm Proteins; D018168:Receptors, Retinoic Acid; D014212:Tretinoin