A Novel Homeobox Protein Which Recognizes a TGT Core and Functionally Interferes with a Retinoid-responsive Motif (∗)

We describe here a novel homeobox gene, denoted TGIF (5′TG3' interacting factor), which belongs to an expanding TALE (three amino acid loop extension) superclass of atypical homeodomains. The TGIF homeodomain binds to a previously characterized retinoid X receptor (RXR) responsive element from...

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Bibliographic Details
Published in:The Journal of biological chemistry 1995-12, Vol.270 (52), p.31178-31188
Main Authors: Bertolino, Eric, Reimund, Bernard, Wildt-Perinic, Dunja, Clerc, Roger G.
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Animals
Base Sequence
DNA, Complementary
Genes, Homeobox
Homeodomain Proteins - genetics
Homeodomain Proteins - metabolism
Humans
Molecular Sequence Data
Promoter Regions, Genetic
Protein Binding
Rats
Receptors, Retinoic Acid - metabolism
Repressor Proteins
Retinoid X Receptors
Retinol-Binding Proteins - genetics
Retinol-Binding Proteins - metabolism
Retinol-Binding Proteins, Cellular
Sequence Homology, Nucleic Acid
Transcription Factors - metabolism
Transcriptional Activation
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Summary:We describe here a novel homeobox gene, denoted TGIF (5′TG3' interacting factor), which belongs to an expanding TALE (three amino acid loop extension) superclass of atypical homeodomains. The TGIF homeodomain binds to a previously characterized retinoid X receptor (RXR) responsive element from the cellular retinol-binding protein II promoter (CRBPII-RXRE), which contains an unusual DNA target for a homeobox. The interactions of both the homeoprotein TGIF and receptor RXRα with the CRBPII-RXRE DNA motif occur on overlapping areas and generate a mutually exclusive binding in vitro. Transient cellular transfections demonstrate that TGIF inhibits the 9-cis-retinoic acid-dependent RXRα transcription activation of the retinoic acid responsive element. TGIF transcripts were detected in a restricted number of tissues. The canonical binding site of TGIF is conserved and is an integral part of several responsive elements which are organized like the CRBPII-RXRE. Hence, a novel auxiliary factor to the steroid receptor superfamily may participate in the transmission of nuclear signals during development and in the adult, as illustrated by the down-modulation of the RXRα activities.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.270.52.31178