Estrogen receptor activation function 2 (AF-2) is essential for hormone-dependent transactivation and cell transformation induced by a v-Jun DNA binding domain-estrogen receptor chimera.
A chimeric protein consisting of the estrogen receptor alpha ligand binding domain (ER-alpha LBD) fused to the DNA binding domain (DBD) of the v-Jun oncoprotein, deltavJ-hER, was previously shown to elicit estradiol-dependent transcriptional activation and cell transformation. Remarkably, in the unliganded state deltavJ-hER is not inert, but rather inhibits cell proliferation. To understand the molecular basis for these opposite effects on cell growth, we investigated the effect of estradiol on deltavJ-hER function. We find that deltavJ-hER is localised to the cell nucleus and capable of binding TPA-response element (TRE) DNA recognition sites in the presence and absence of estradiol, indicating that these properties are unlikely to be the targets of hormonal regulation. In contrast, a mutant derivative of deltavJ-hER in which amino acid substitutions selectively disrupt activation function 2 (AF-2) function is unable to elicit estradiol-dependent transcription or cell transformation, even though DNA binding is not impaired. Taken together, these observations establish that estrogen receptor AF-2 activity is essential for cell transformation by deltavJ-hER.
Dunn
Catherine A
CA
Beatson Institute for Cancer Research, Cancer Research UK Beatson Laboratories, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK. cdunn@bccrc.ca
Clark
William
W
Black
Elizabeth J
EJ
Gillespie
David A F
DA
D000818:Animals; D001665:Binding Sites; D004247:DNA / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D056918:Nuclear Receptor Coactivators; D016759:Oncogene Protein p65(gag-jun) / Q000378:metabolism*; D011506:Proteins / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D015533:Transcriptional Activation
D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; C455500:NCOA7 protein, human; D056918:Nuclear Receptor Coactivators; D016759:Oncogene Protein p65(gag-jun); D011506:Proteins; D011960:Receptors, Estrogen; D004958:Estradiol; D004247:DNA