The Transcriptional Activity of Estrogen Receptor-α Is Dependent on Ca2+/Calmodulin

Lu Li, Zhigang Li, David B. Sacks
2005 Journal of Biological Chemistry  
Estrogen binds to estrogen receptors in cells, thereby activating the receptors and eliciting biological effects. One of the best characterized effects of estrogen receptor-␣ (ER␣) is transcriptional activation that regulates selected target genes in the nucleus. Work from several laboratories has documented a Ca 2؉ -dependent interaction between ER␣ and calmodulin. In addition, we previously showed that antagonism of calmodulin function in cells prevented estradiol from inducing ER␣
more » ... onal activity, suggesting that association of ER␣ with calmodulin participates in ER␣ function. In this study we adopted a multifaceted approach to directly address this hypothesis. The calmodulin binding domain on ER␣ was identified and several mutant ER␣ constructs unable to bind calmodulin were generated. Elimination of calmodulin binding prevented estradiol from stimulating ER␣ transcriptional activation. Essentially identical results were obtained when intracellular Ca 2؉ was chelated with the cell-permeable chelator 1,2-bis(o-aminophenoxy)ethane-N,N,N,N-tetraacetic acid tetra(acetoxymethyl)ester (BAPTA-AM). Moreover, CaM1234, a calmodulin mutant that is unable to bind Ca 2؉ , functioned as a dominant negative construct. Transfection of cells with CaM1234 reduced estradiolstimulated ER␣ transcriptional activity. These data indicate that binding to calmodulin is required for normal transcriptional function of ER␣.
doi:10.1074/jbc.m410642200 pmid:15657064 fatcat:5l5zulmtkjeydgxhdzoxphnngq