Dominant negative retinoic acid receptor beta.
Induction of the retinoic acid receptor beta 2 (RAR beta 2) gene by retinoic acid (RA) is mediated by a RA response element (RARE), which represents a high affinity binding site for RAR/RXR heterodimers acting at this site as RA-inducible transcription activators. In RA resistant RAC65 cells, RAR beta 2 induction is blocked due to expression of a truncated RAR alpha acting as a dominant negative repressor. Here we show that exogenous expression of RAR but not RXR can restore RA-dependent RAR beta 2 promoter activation in RAC65 cells. Structure-function analysis of hRAR beta 2 mutants in RAC65 cells shows, that the transactivation function required to restore RAR beta 2 promoter activation is dependent on the DNA binding, dimerization and RA-dependent transactivation properties of hRAR beta 2, which are retained in a mutant (beta delta 409) lacking the F domain. By contrast, dominant repression of RA-dependent mRAR beta 2 promoter activation by hRAR beta 2 mutants is independent of the DNA binding or RA-dependent transactivation function but requires a region (residues 204-384) in hRAR beta 2 involved in heterodimerization with RXR. These data extend previous observations on structure-function of RARs and provides tools for studying the role of retinoids and RARs during vertebrate development.
Hubrecht Laboratory, Netherlands Institute for Developmental Biology, Utrecht.
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Shen
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van der Saag
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Kruijer
D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics*; D005799:Genes, Dominant; D008969:Molecular Sequence Data; D009154:Mutation; D011401:Promoter Regions, Genetic; D011956:Receptors, Cell Surface / Q000235:genetics; D018168:Receptors, Retinoic Acid; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics*; D047488:Retinoid X Receptors; D014157:Transcription Factors; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D011956:Receptors, Cell Surface; D018168:Receptors, Retinoic Acid; D012097:Repressor Proteins; D047488:Retinoid X Receptors; D014157:Transcription Factors; D014212:Tretinoin