Identification of direct repeat 4 as a positive regulatory element for the human TR4 orphan receptor. A modulator for the thyroid hormone target genes.
While the TR4 orphan receptor (TR4) is able to repress the expression of its target genes via its interaction with the direct repeat 1-hormone response element (DR1-HRE) and DR2-HRE, we now report that TR4 can also induce the transcriptional activity of the reporter gene containing a DR4-HRE via chloramphenicol acetyltransferase assay. Electrophoretic mobility shift assay and Scatchard analysis reveal a strong binding affinity (dissociation constant = 2 nM) between TR4 and DR4-HRE. The induction mediated by TR4 was detected not only in the synthetic DR4-HRE but also in some genes, such as rat alpha-myosin heavy-chain and S14 genes, containing the DR4 or DR4-like motif, which have been suggested to be the response elements for a thyroid hormone receptor. Our data also demonstrate this TR4-mediated gene induction is TR4 dose- and DR4 sequence-dependent. Together, our data suggest that DR4-HRE can be a positive regulatory element for TR4, which may be able to induce the transcriptional activity of the genes containing such positive HREs.
Lee
Y F
YF
Comprehensive Cancer Center, University of Wisconsin, Madison, Wisconsin 53792, USA.
Pan
H J
HJ
Burbach
J P
JP
Morkin
E
E
Chang
C
C
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000378:metabolism; D017930:Genes, Reporter; D016325:HIV Long Terminal Repeat; D006801:Humans; D007700:Kinetics; D016297:Mutagenesis, Site-Directed; D018995:Myosin Heavy Chains / Q000096:biosynthesis; D009419:Nerve Tissue Proteins / Q000096:biosynthesis / Q000378:metabolism*; D014176:Protein Biosynthesis; D051381:Rats; D011987:Receptors, Steroid / Q000096:biosynthesis / Q000378:metabolism*; D011988:Receptors, Thyroid Hormone / Q000096:biosynthesis / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; C490515:NR2C2 protein, human; D009419:Nerve Tissue Proteins; C092882:Nr2c2 protein, rat; D011987:Receptors, Steroid; D011988:Receptors, Thyroid Hormone; D011993:Recombinant Fusion Proteins; D018995:Myosin Heavy Chains