Identification of Direct Repeat 4 as a Positive Regulatory Element for the Human TR4 Orphan Receptor

• Published in: The Journal of biological chemistry 1997-05, Vol.272 (18), p.12215-12220
• Main Authors: Lee, Yi-Fen, Pan, Huei-Ju, Burbach, J. Peter H., Morkin, Eugene, Chang, Chawnshang
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.272.18.12215

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 n m ) 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 α-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.