TR4 orphan receptor represses the human steroid 21-hydroxylase gene expression through the monomeric AGGTCA motif.
The human TR4 orphan receptor (TR4) is a member of the nuclear receptor superfamily. It functions as a transcriptional factor which regulates and controls many important physiological functions. It has been documented that TR4 may bind as a homodimer to a DNA response element containing two direct repeats of the AGGTCA consensus motif. Surprisingly, our data reveal that the expression of the human steroid 21-hydroxylase (21-OHase) gene could be repressed by TR4 via the monomeric AGGTCA motif (-228TR4RE) at its 5' flanking region (nucleotide numbers 1431-1444, 5'-GGAAAAAGGTCAGG-3'). Electrophoretic mobility shift assay showed specific binding with a dissociation constant of 0.4 nM between TR4 and the monomeric -288TR4RE motif. However, TR4 does not form heterodimers with either retinoid X receptor alpha or SHP (short heterodimer partner) orphan receptor. Additionally, both dual-luciferase and chloramphenicol acetyltransferase assays demonstrated that TR4 can function as a repressor via the -228TR4RE of the 21-OHase gene. In conclusion, our data suggest that TR4 may bind to a monomeric DNA response element and play an important role in the suppression of the 21-OHase gene expression.
Lee
H J
HJ
Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan, 974, Republic of China. hjlee@mail.ndhu.edu.tw
Lee
Y F
YF
Chang
C
C
D020121:5' Untranslated Regions / Q000235:genetics; D020816:Amino Acid Motifs / Q000502:physiology; D001667:Binding, Competitive / Q000502:physiology; D004247:DNA / Q000378:metabolism; D019281:Dimerization; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D009419:Nerve Tissue Proteins / Q000494:pharmacology / Q000502:physiology*; D011485:Protein Binding / Q000502:physiology; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D011987:Receptors, Steroid / Q000502:physiology*; D011988:Receptors, Thyroid Hormone; D020218:Response Elements / Q000502:physiology; D013255:Steroid 21-Hydroxylase / Q000037:antagonists & inhibitors* / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity / Q000502:physiology
D020121:5' Untranslated Regions; C490515:NR2C2 protein, human; D009419:Nerve Tissue Proteins; D018160:Receptors, Cytoplasmic and Nuclear; D011987:Receptors, Steroid; D011988:Receptors, Thyroid Hormone; D004247:DNA; D013255:Steroid 21-Hydroxylase