Estrogen receptor-related receptor alpha 1 interacts with coactivator and constitutively activates the estrogen response elements of the human lactoferrin gene.
The human estrogen receptor-related receptor (ERRalpha1, NR3B1a) was shown to bind a steroidogenic factor binding element (SFRE), TCAAGGTCATC, 26 base pairs upstream from the estrogen response element (ERE) of the human lactoferrin gene promoter. A mutation made at SFRE significantly reduced estrogen-dependent transcription from the lactoferrin ERE in human endometrial cells. In this study, we demonstrated that ERRalpha1 binds both SFRE and ERE elements and constitutively transactivates the lactoferrin gene promoter. In DNase I footprinting protection analysis, both SFRE and ERE regions were protected by glutathione S-transferase-ERRalpha1 fusion protein. The receptor formed two protein-DNA complexes with either SFRE or ERE in electrophoresis mobility shift assay. Homodimerization of ERRalpha1 was confirmed with the mammalian two-hybrid system. ERRalpha1 activates reporter constructs containing various types of estrogen response elements in endometrial and non-endometrial cells in transient transfection experiments. Overexpressing the coactivator, SRC1a or GRIP1, further enhances ERRalpha1-induced transcriptional activity. We demonstrated that the AF2 domain of ERRalpha1 is essential for the transactivation function and that deletion or mutation at this region abrogates the activation capability. Protein-protein interaction between the SRC1a and ERRalpha1 C terminus was confirmed with a GST glutathione S-transferase "pull-down" assay. When comparing ERRalpha1 and the estrogen receptor alpha (ERalpha) in many of the experiments, we found that ERalpha can also bind SFRE of the lactoferrin gene and transactivate the promoter activity in a ligand-dependent manner. The present study demonstrated that ERRalpha1 binds similar DNA elements as ERalpha and confers its transactivation function constitutively. Therefore, ERRalpha1 may actively modulate the estrogen response of lactoferrin gene as well as other estrogen-responsive genes.
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Gene Regulation Group, Laboratory of Reproductive and Developmental Toxicology, NIEHS, National Institutes of Health, Research Triangle Park, North Carolina 27709, USA.
Teng
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D018983:DNA Footprinting; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D051548:Histone Acetyltransferases; D006801:Humans; D007781:Lactoferrin / Q000235:genetics*; D009154:Mutation; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D011401:Promoter Regions, Genetic; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012045:Regulatory Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D014407:Tumor Cells, Cultured; D000097983:ERRalpha Estrogen-Related Receptor
D004268:DNA-Binding Proteins; D051548:Histone Acetyltransferases; D007781:Lactoferrin; D056920:Nuclear Receptor Coactivator 1; D051958:Nuclear Receptor Coactivator 2; D018160:Receptors, Cytoplasmic and Nuclear; D011960:Receptors, Estrogen; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D000097983:ERRalpha Estrogen-Related Receptor; C498001:NCOA2 protein, human; C538859:NCOA1 protein, human