Estrogen Receptor β Antibody #5513

Estrogen Receptor β (ER β) is a member of the nuclear receptor superfamily of transcription factors and was discovered to be encoded by a gene (ESR2) distinct from that encoding Estrogen Receptor α (ER α) (1,2). While studies have revealed that alternative splicing generates mutiple isoforms of ER β that differ at their respective C-termini and in tissue distribution, ER β1 is believed to be the longest and only fully functional isoform (3,4). Indeed, it has been reported that shorter isoforms of ER β (ER β2, β4, and β5) can heterodimerize with ER β1 and enhance its transcriptional activity in an estradiol-dependent manner (4). ER β is expressed in a wide range of normal and malignant tissues, many of which coexpress ER α. It is proposed that ER β has an antiproliferative role, perhaps through heterodimerization with ER α and repression of its transcriptional activity at estrogen response elements (5,6). Recent studies have revealed that expression of ESR2 is subject to epigenetic regulation and that loss of ER β expression positively contributes to epithelial-mesenchymal transition and enhanced invasiveness in prostate cancer (7,8). ER β has also been found to be negatively regulated at the posttranslational level through phosphorylation of its AF-1 domain, which promotes its ubiquitin-dependent proteasomal degradation (9,10).